Features, Events, and Processes: System Level ANL-WIS-MD-0000019 REV 01 April 2004 1. PURPOSE The primary purpose of this analysis is to evaluate System Level features, events, and processes (FEPs). The System Level FEPs typically are overarching in nature, rather than being focused on a particular process or subsystem. As a result, they are best dealt with at the system level rather than addressed within supporting process-level or subsystem level analyses and models reports. The System Level FEPs also tend to be directly addressed by regulations, guidance documents, or assumptions listed in the regulations; or are addressed in background information used in development of the regulations. This evaluation determines which of the System Level FEPs are excluded from modeling used to support the total system performance assessment for license application (TSPA-LA). The evaluation is based on the information presented in analysis reports, model reports, direct input, or corroborative documents that are cited in the individual FEP discussions in Section 6.2 of this analysis report. By default, FEPs are included in the TSPA-LA unless they can be excluded based on low probability, low consequence, or by regulation. The U.S. Nuclear Regulatory Commission (NRC) provides the evaluation criteria, or screening criteria in the Code of Federal Regulations (CFR) at 10 CFR 63.114 (d, e, and f) ([DIRS 156605]). The NRC regulations also incorporate the performance standards of the U.S. Environmental Protection Agency (EPA) found at 40 CFR Part 197 ([DIRS 165519]). A FEP can be excluded from the TSPA-LA per 10 CFR 63.114(d) ([DIRS 156605]) by showing that the probability of occurrence is less than 1 in 10,000 in 10,000 years (or an approximately equivalent annualized probability of 10-8). A FEP also can be excluded from the TSPA-LA per 10 CFR 63.114 (e or f) ([DIRS 156605]) by showing that omitting the FEP would not significantly change the resulting radiological exposure to the reasonably maximally exposed individual (RMEI) or the radionuclide release to the accessible environment. A FEP may also be excluded “by regulation” based on characteristics, definitions, or concepts specifically stated in applicable NRC regulations. This analysis report documents changes to the System Level FEP list that have occurred since issuance of REV 00 (CRWMS M&O 2000 [DIRS 144180]). These changes resulted from reevaluation of the FEP list, as outlined in The Enhanced Plan for Features, Events, and Processes (FEPs) at Yucca Mountain (BSC 2002 [DIRS 158966]) and the KTI Letter Report, Response to Additional Information Needs on TSPAI 2.05 and TSPAI 2.06 (Freeze 2003 [DIRS 165394]). Reorganization and redefinition of FEPs between the total system performance assessment for site recommendation (TSPA-SR) and the TSPA-LA is specifically addressed in Section 6.1. Because this analysis report is intended for use as a source of information to populate a FEP database, it contains a self-identifying reference to help maintain traceability (i.e., in this analysis report) within the text of Section 6.2 and subsections. This revision addresses updates in the Yucca Mountain Project (YMP) administrative procedures (APs) as they pertain to this analysis report; the current procedures are discussed in Sections 2 and 3. Sections 4, 5, and 6 incorporate updates to the technical basis and assumptions that are provided in supporting analysis and modeling reports (collectively, AMRs) and also provide ANL-WIS-MD-000019 REV 01 1-1 April 2004 additional information pertaining to the relevant FEP-related acceptance criteria presented in the Yucca Mountain Review Plan, Final Report NUREG-1804 (NRC 2003 [DIRS 163274]), herein referred to as the NUREG-1804. The initial report (REV 00) was originally scoped based on consideration of a repository with backfill and drip shields, as described in the License Application Design Selection Report (CRWMS M&O 1999, EDA II [DIRS107292]). During preparation of REV 00, however, considerations expanded to evaluate changes to the design, including the no-backfill repository design and changes to resolve certain thermal design issues, reorientation of the drift azimuths, and 70,000 metric ton uranium and 95,000 metric ton uranium designs (CRWMS M&O 2000 [DIRS 150088]; CRWMS M&O 2000 [DIRS 149137]). This version of the analysis report (REV 01) is based on the TSPA-LA design as presented in the drawings listed in Section 4 of this analysis report. 1.1 PLANNING AND DOCUMENTATION Documentation requirements for this analysis report are described in the technical work plan (TWP) entitled Technical Work Plan for: Decisions Support and Documentation Department Activities (BSC 2004 [DIRS 168024]). Changes in the assigned System-Level FEP list for TSPA-LA resulted from the planned work scope and are further described in Table 6-1. 1.2 SCOPE The scope of this report is to describe, evaluate, and document screening decisions and technical bases for the System Level FEPs for TSPA-LA for both the included and the excluded FEPs. This approach differs from other FEP AMRs for TSPA-LA. In other FEP AMRs, the screening decision and technical basis for an included FEP is evaluated and documented in a supporting AMR, and the decision and evaluation is summarized and, if needed, updated in the FEP AMR. That approach works well for FEPs that are focused on a particular process, interrelated processes, or a defined subsystem. By contrast, the System Level FEPs are overarching and are not focused on a particular process or subsystem and, therefore, evaluation of the FEPs cannot be assigned or mapped to a specific AMR or to a set of supporting AMRs. This difference in approach is particularly reflected in Section 4 of this report, with direct inputs being provided for both the included and the excluded FEPs. Consequently, this FEP AMR provides the documentation and technical basis for both included and excluded System Level FEPs, as required in 10 CFR 63.114 (d, e, and f) [DIRS 156605]). For System Level FEPs that are included in the TSPA-LA, this AMR provides a TSPA-LA disposition, which summarizes how the FEP has been included and addressed in the TSPA-LA model, and cites the various analysis reports and model reports (collectively, AMRs) or other direct input that support inclusion of the FEP. For System Level FEPs that are excluded from the TSPA-LA it provides a screening argument, which identifies the basis for the screening decision (i.e., low probability, low consequence, or by regulation) and discusses the technical basis that supports that decision. For TSPA-SR, 26 of the FEPs listed in the YMP FEP Database were initially grouped as System Level FEPs (BSC 2001, Appendix B [DIRS 154365]). Subsequently, five FEPs were reassigned ANL-WIS-MD-000019 REV 01 1-2 April 2004 from disruptive events (i.e., salt creep, salt diapirism and dissolution, diapirism, diagenesis, and metamorphism) because they did not deal with disruptive events as defined by the regulations (i.e., the FEPs did not address volcanism, seismicity, criticality or human intrusion). The resulting 31 TSPA-SR FEPs were grouped as “system-level” FEPs rather than being mapped to process-oriented or system-oriented AMRs. The scope of activities for this report, starting with the TSPA-SR System Level FEP list, was described in The Enhanced Plan for Features, Events, and Processes (FEPs) at Yucca Mountain (BSC 2002 [DIRS 158966]), and the results of those activities for TSPA-LA System Level FEPs are documented in detail in Section 6.1. These activities included FEP reorganization (eliminating primary and secondary FEP classifications and eliminating redundant FEPs); change in the level of detail of FEP descriptions; and reevaluation of FEP screening decisions, arguments, and TSPA dispositions. The reorganization and reevaluation of the System Level FEPs started with the FEP list extracted from DTN: MO0312SEPFEPS5.000 [DIRS 167431], which was modified during the review process for this analysis report. The reorganization and reevaluation of the System Level FEPs have resulted in a revised and reorganized list of 33 System Level FEPs for TSPA-LA. The differences in the TSPA-SR list and the TSPA-LA list for System FEPs include removing and reassigning FEP 3.2.10.00.0A (atmospheric transport of contaminants), and adding FEP 2.1.01.04.0A (repository scale spatial heterogeneity of emplaced waste) to the System Level FEP list. Also, two new FEPs were added to address the joint concurrence of disruptive events with the human intrusion stylized analysis. FEP 1.4.02.03.0A (igneous events) precedes human intrusion, and FEP 1.4.02.04.04 (seismic event) precedes human intrusion. Other changes are detailed in Section 6.1. The list of TSPA-LA System Level FEPs is given in Table 1-1, which reflects the grouping of the System-Level FEPs by topic and their numeric ordering by FEP number within each topic. Each FEP discussion also provides a list of related FEPs by FEP number. The associated FEP AMRs are listed in DTN: MO0312SEPFEPS5.000 [DIRS 167431]. In cases where a FEP covers multiple technical areas and is shared with other FEP AMRs, this analysis report provides only a partial technical basis for the screening decision as it relates to system-level concerns. The sharing FEP AMRs are listed in DTN: MO0312SEPFEPS5.000 [DIRS 167431]. The full technical basis for these shared FEPs is addressed, collectively, by all of the sharing FEP AMRs. Only one System-Level FEP, FEP 1.1.11.00.0A, which addresses monitoring of the repository, is shared with another analysis report as indicated in last column of Table 1.1. The resulting System Level FEP list has been compared with the list of external hazards presented in MGR External Events Hazards Screening Analysis (BSC 2003 [DIRS 163999]), which deals with external events occurring within the operational and preclosure time frame. Within the constraints of postclosure concerns, as opposed to preclosure considerations, the FEP lists were found to be consistent. ANL-WIS-MD-000019 REV 01 1-3 April 2004 Table 1-1. System Level FEPs for TSPA-LA FEP Addressed in Number FEP Name Section Sharing FEP AMR ASSESSMENT BASIS AND MODELING REQUIREMENTS FEPs (Section 6.2.1) 0.1.02.00.0A Timescales of Concern 6.2.1.1 System Level Only 0.1.03.00.0A Spatial Domain of Concern 6.2.1.2 System Level Only 0.1.09.00.0A Regulatory Requirements and Exclusions 6.2.1.3 System Level Only 0.1.10.00.0A Model and Data Issues 6.2.1.4 System Level Only 1.1.07.00.0A Repository Design 6.2.1.5 System Level Only 1.1.13.00.0A Retrievability 6.2.1.6 System Level Only 2.1.01.04.0A Repository-Scale Spatial Heterogeneity of Emplaced Waste 6.2.1.7 System Level Only PROCESS AND SITE-CONTROL FEPs (Section 6.2.2) 1.1.05.00.0A Records and Markers for the Repository 6.2.2.1 System Level Only 1.1.08.00.0A Inadequate Quality Control and Deviations from Design 6.2.2.2 System Level Only 1.1.09.00.0A Schedule and Planning 6.2.2.3 System Level Only 1.1.10.00.0A Administrative Control of the Repository Site 6.2.2.4 System Level Only 1.1.11.00.0A Monitoring of the Repository 6.2.2.5 System Level, UZ 1.1.12.01.0A Accidents and Unplanned Events During Construction and 6.2.2.6 System Level Only Operation HUMAN INTRUSION FEPs (Section 6.2.3) 1.4.02.01.0A Deliberate Human Intrusion 6.2.3.1 System Level Only 1.4.02.02.0A Inadvertent Human Intrusion 6.2.3.2 System Level Only 1.4.02.03.0A Igneous Event Precedes Human Intrusion 6.2.3.3 System Level Only 1.4.02.04.01 Seismic Event Precedes Human Intrusion 6.2.3.4 System Level Only 1.4.03.00.0A Unintrusive Site Investigation 6.2.3.5 System Level Only 1.4.04.00.0A Drilling Activities (Human Intrusion) 6.2.3.6 System Level Only 1.4.04.01.0A Effects of Drilling Intrusion 6.2.3.7 System Level Only 1.4.05.00.0A Mining and Other Underground Activities (Human 6.2.3.8 System Level Only Intrusion) 1.4.11.00.0A Explosions and Crashes (Human Activities) 6.2.3.9 System Level Only 3.3.06.01.0A Repository Excavation 6.2.3.10 System Level Only MISCELLANEOUS GEOLOGIC AND ASTRONOMIC FEPs (Section 6.2.4) 1.2.05.00.0A Metamorphism 6.2.4.1 System Level Only 1.2.08.00.0A Diagenesis 6.2.4.2 System Level Only 1.2.09.00.0A Salt Diapirism and Dissolution 6.2.4.3 System Level Only 1.2.09.01.0A Diapirism 6.2.4.4 System Level Only 1.5.01.01.0A Meteorite Impact 6.2.4.5 System Level Only 1.5.01.02.0A Extraterrestrial Events 6.2.4.6 System Level Only 1.5.03.01.0A Changes in the Earth's Magnetic Field 6.2.4.7 System Level Only 1.5.03.02.0A Earth Tides 6.2.4.8 System Level Only 2.2.06.05.0A Salt Creep 6.2.4.9 System Level Only 2.3.13.03.0A Effects of Repository Heat on the Biosphere 6.2.4.10 System Level Only FEPs = features, events, and processes ANL-WIS-MD-000019 REV 01 1-4 April 2004 1.3 SCIENTIFIC ANALYSIS LIMITATIONS AND USE The intended use of this analysis report is to provide FEP screening information for a project specific FEP database, and to promote traceability and transparency for both included and excluded FEP dispositions and screening arguments for the System Level FEPs. This analysis report is intended to be used as the source documentation, and to provide the technical basis and supporting arguments, for inclusion or exclusion of System Level FEPs within or from the TSPA-LA model. The following limitations apply to this analysis report: • Because this analysis report cites other AMRs and controlled documents as direct input, the limitations of this analysis report inherently include any limitations or constraints described in the cited AMRs or controlled documents. In particular, the results of the waste package degradation analyses cited from BSC 2003 (Section 6.7.1 [DIRS 161317]) result from the use of representative thermal hydrologic history files produced to allow model runs to be exercised in the cited report. The actual drip shield and waste package degradation profiles used in the TSPA-LA Model will make use of the actual thermal hydrologic history files appropriate for the repository. Because representative histories were used, significant differences in the degradation profile generated for TSPA-LA is not expected. • For screening purposes, this analysis report generally uses mean values of probabilities, mean amplitude of events, or mean value of consequences (e.g., mean time to waste package degradation) as a basis for reaching an include/exclude decision. Mean values are determined based on the range of possible values. • The results of the FEP screening presented herein are specific to the repository design and processes for YMP available at the time of the TSPA-LA. Changes in direct inputs listed in Section 4.1, in baseline conditions used for this evaluation, or in other subsurface conditions, will need to be evaluated to determine whether the changes are within the limits stated in the FEP evaluations. Engineering and design changes are subject to evaluation to determine whether there are any adverse impacts to safety, as codified at 10 CFR 63.73 and in Subparts F and G ([DIRS 156605]). (See also the requirements at 10 CFR 63.44 ([DIRS 156605]). ANL-WIS-MD-000019 REV 01 1-5 April 2004 INTENTIONALLY LEFT BLANK ANL-WIS-MD-000019 REV 01 1-6 April 2004 2. QUALITY ASSURANCE This work constitutes an analysis report, and the documentation has been prepared according to AP-SIII.9Q, Scientific Analyses, and in accordance with related procedures and guidance documents as outlined in the TWP. Development of this analysis report and the supporting analyses are subject to the Office of Civilian Radioactive Waste Management (OCRWM) quality assurance (QA) program. (BSC 2004, Section 8.1, Work Package APA0FB [DIRS 168024]). Approved QA procedures identified in the Technical Work Plan for: Decision Support and Documentation Department Activities. (TWP) (BSC 2004, Section 4.1 [DIRS168024]) have been used to conduct and document the activities described in this analysis report. The TWP also identifies applicable controls for the electronic management of data (BSC 2004, Section 8.4 [DIRS 168024]) during the analysis and documentation activities. The report contributes to the analysis and modeling used to support performance assessment. The System Level FEPs documented herein involve the investigations of items or barriers on the Q-list and have the potential to affect the calculation of the performance of the natural barriers and various engineered barrier system (EBS) components included on the Q-list. However, the System Level FEPs themselves do not qualify as “Q-list” items. The evaluations and conclusions do not directly impact engineered features important to safety, as defined in AP-2.22Q, Classification Analyses and Maintenance of the Q-List. ANL-WIS-MD-000019 REV 01 2-1 April 2004 INTENTIONALLY LEFT BLANK ANL-WIS-MD-000019 REV 01 2-2 April 2004 3. COMPUTER SOFTWARE AND MODEL USAGE This analysis report uses no computational software; therefore, this analysis is not subject to software controls. The analyses and arguments presented herein are based on guidance and regulatory requirements, on results of analyses presented and documented in other analysis reports, or on other technical literature. Software and models used in the supporting documents are cited in this analysis report for traceability and transparency purposes but were not used in its development. This analysis report was developed using only commercial off-the-shelf software. Microsoft® Word 2000 used for word processing is exempt from qualification requirements in accordance with LP-SI.11Q, Software Management. The spreadsheet program Microsoft® Excel 2000 was used for calculations as described below. This analysis report provides data qualification documentation (Attachment II) and an analysis package (Attachment IV) for determining the probability of meteorite impact and the resulting crater damage. The spreadsheets in the appendices were written using the standard functions of commercial off-the-shelf software (Microsoft® Excel 2000) and, therefore, are not required to be qualified in accordance with LP-SI.11Q, Section 2.1.6. Microsoft® Excel 2000 was also used to graphically present the meteorite impact probability data and to provide equations and coefficients for a regression analysis using the standard graphical interface for adding trend lines to graphs. There were no applications (routines or macros) developed using this commercial off-the-shelf software. The information provided is sufficient to allow review and checking without recourse to the originator. ANL-WIS-MD-000019 REV 01 3-1 April 2004 INTENTIONALLY LEFT BLANK ANL-WIS-MD-000019 REV 01 3-2 April 2004 4. INPUTS The data, product output, direct input, and other references used in this analysis report were obtained from controlled source documents and other appropriate sources in accordance with the controlling procedure AP-3.15Q, Managing Technical Product Inputs. 4.1 DIRECT INPUTS The procedure for managing inputs categorizes technical product inputs as either direct input or reference only. Direct input constitutes the input used to develop the results or conclusions in a technical product. Direct input is further classified as established fact, data, or vendor data (no vendor data are used in this analysis). There are no assumptions needing further confirmation for this analysis report. Software and models developed in the supporting documents are cited for traceability and transparency purposes; however, they were not used directly in development of the analyses and arguments presented herein. 4.1.1 Site Characterization and/or Site-Specific Data and Expert Elicitations (Data) This subsection identifies qualified data and other factual information used as direct input in this analysis report. Table 4-1 lists all data tracking numbers (DTNs) cited to justify the FEP inclusion or exclusion. This report also cites to the Probabilistic Seismic Hazard Analyses for Fault Displacement and Vibratory Ground Motion at Yucca Mountain, Nevada (or PSHA) (CRWMS M&O 1998 [DIRS 103731]) regarding the magnitude of earthquakes that were addressed as part of the PSHA, the results of which were used as inputs for the seismic evaluations for seismic-related FEPs. The PSHA presents the ground motion and fault displacement evaluations resulting from the expert-elicitation process, and per AP-3.15Q are considered as qualified data. 4.1.2 Product Outputs (Data) Other direct input used in this analysis report has been obtained from controlled source documents (product output) using the appropriate document identifiers or records system accession numbers. Sources of such information include, but are not limited to, YMP-prepared databases, drawings, and other technical documents. 4.1.2.1 YMP FEP Database The FEP list used for the TSPA-LA screening presented in this analysis report was extracted from DTN: MO0312SEPFEPS5.000 ([DIRS 167431]). The list of FEPs was reviewed for possible System Level FEPs and evaluated for appropriateness of use and comprehensiveness, and was determined to be comparable and traceable to the list of System Level FEPs presented for site recommendation (SR) and suitable for use as a preliminary list of System Level FEPs to be further evaluated for LA. Modifications to the System Level FEP List for LA are detailed in Section 6.1.1 of this analysis report. ANL-WIS-MD-000019 REV 01 4-1 April 2004 Table 4-1. Data Used for the System Level FEP Evaluations Section Data Name Data Description DTN/Data Source ASSESSMENT BASIS AND MODELING REQUIREMENTS FEPs (Section 6.2.1) (none used) PROCESS AND SITE-CONTROL FEPs (Section 6.2.2) (none-used) HUMAN INTRUSION FEPs (Section 6.2.3) 6.2.3.4 Attachment III Properties of Alloy 22 (UNS N06022)2 Yield Strength, Tensile Strength, Modulus of Elasticity MO0003RIB00071.000 [DIRS 148850] Properties of Ti Grades 7 and 16 Yield Strength, Tensile Strength, Modulus of Elasticity MO0003RIB00073.000 [DIRS 152926] Properties of 316N Stainless Yield Strength, Tensile Strength, Modulus of Elasticity MO0003RIB00076.000, [DIRS 153044] Rock Material Properties Unconfined Compressive Strength MO0311RCKPRPCS.003 [DIRS 166073] MISCELLANEOUS GEOLOGIC AND ASTRONOMIC FEPs (Section 6.2.4) 6.4.2.5 Attachment IV Depth of lithologic contacts for the PTn Contact depths for all borings located in or adjacent to the repository footprint MO0004QGFMPICK.000 [DIRS 152554]: (Depth to contacts for Tpp, Tpt, Tptrv3, Tptrv1) Magnitude of earthquakes considered during expert elicitation Included Magnitude 5 to Magnitude 7 events CRWMS M&O 1998, Section 4 [DIRS 103731] DTN = data tracking number, FEP = feature, event, and process, DIRS = Document Input Reference System 4.1.2.2 Technical Reports and Controlled Documents Other direct input used to address safety and waste isolation issues have also been obtained from controlled sources. Table 4-2 lists any AMRs or other “Q” products that satisfy the definition of “Product Output” as given in AP-3.15Q and that are cited as a technical basis for including or excluding a System Level FEP. Sources of such information include, but are not limited to, supporting YMP AMRs, YMP Technical Reports, and other YMP documents and databases prepared in accordance with procedures controlling “Q”–status documents. ANL-WIS-MD-000019 REV 01 4-2 April 2004 Table 4-2. Controlled Documents Used as Basis for the System Level FEP Evaluations Section Type of Input Value/Contribution Input Source ASSESSMENT BASIS AND MODELING REQUIREMENTS FEPs (Section 6.2.1) 6.2.1.1 Timescale and duration of TSPA-LA analyses 10,000 years and extended to 20,000 years to address uncertainties BSC 2003, Sections 1.3 and 9.1 [DIRS 166296] 6.2.1.2 Spatial domain of concern Extends from the land surface through the UZ, through the repository, into the (SZ), and laterally away from the repository to the location of the RMEI at 18 km from the repository BSC 2003, Section 5.1 [DIRS 166296] 6.2.1.3 Demonstration of compliance with applicable regulations Assignment of regulatory applicability and responsibility to various YMP organizations Canori and Leitner 2003 [DIRS 166275] BSC 2003 Treatment of various modeling aspects in TSPA and summary of method of inclusion [DIRS 166296] for the following specific section and related information: 6.2.1.4 Compliance with modeling requirements Alternative conceptual models Abstractions Parameter uncertainty Section 3.3 Section 3.4 Section 3.5 Use of geologic, hydrologic and geochemical data Section 5.1 TSPA–LA Model validation approach Section 7 Uncertainty analysis Section 8.1 6.2.1.5 Method for recognizing change in conditions and/or inadequate design Performance confirmation plan requirements Snell et al. 2003 [DIRS 166219] 6.2.1.5 and 6.2.1.6 Method and approach for including design elements Summary of method of inclusion. Design elements are implicitly included through the use of information extracted from project EDs for EBS, waste package, and drip shield and used in related models. BSC 2003, Section 5.1 [DIRS 166296] 6.2.1.7 Method of incorporating waste heterogeneity at the repository scale Summary of method of inclusion BSC 2003, pp. 71-73; 77-78; and 81 [DIRS 166296] PROCESS AND SITE-CONTROL FEPs (Section 6.2.2) 6.2.2.2 Method for recognizing change in conditions and/or inadequate design Performance confirmation plan requirements Snell et al. 2003 [DIRS 166219] 6.2.2.5 Performance confirmation plan Precludes significant effects from required and unplanned monitoring activities Snell et al. 2003 [DIRS 166219] HUMAN INTRUSION FEPs (Section 6.2.3) 6.2.3.2, 6.2.3.6, 6.2.3.7, Attachment III Lifetimes for drip shield and waste package Under nominal case conditions, drip shield failures occurring after about 35,000 years. The first failures of the waste package occur on the order of 100,000 years BSC 2003, Section 6.7.1 [DIRS 161317] ANL-WIS-MD-000019 REV 01 4-3 April 2004 Table 4-2. Controlled Documents Used as Basis for the System Level FEP Evaluations (Continued) Section Type of Input Value/Contribution Input Source HUMAN INTRUSION FEPs (Section 6.2.3) (Continued) 6.2.3.3 Probability of igneous intrusion Computed mean annual frequency of intersection of the repository footprint by a dike is 1.7 × 10-8 BSC 2003, Table 22 [DIRS 163769] 6.2.3.4 Probabilities and associated damage states for seismic events A summary of the damage abstraction related to seismic ground motion BSC 2003, Sections 6.6.5, 6.3.2, and 6.5.2 [DIRS 167780] Attachment III Summary of Rock Properties for lithophysal and nonlithophysal units Values for Young’s modulus and for tensile strength BSC 2003, Tables V-5, V-6, V-8, V9 [DIRS 162711] BSC 2003, Figure 8-45 [DIRS 166660] 6.2.3.9 Depth of repository below surface Surface topography contours above the repository BSC 2004, Figure 4 [DIRS 168029] MISCELLANEOUS GEOLOGIC AND ASTRONOMIC FEPs (Section 6.2.4) 6.2.4.1 Cumulative fault slip rate values Strain rate has resulted in cumulative fault slip rates of 0.001–0.03 millimeter/year (mm/yr) BSC 2004, Table 6 [DIRS 168030] 6.2.4.3; 6.2.4.9 Lithologic and stratigraphic descriptions Yucca Mountain composed of sequence of volcanic-related deposits BSC 2004, Section 6.5.1.4 and Table 4 [DIRS 168029] 6.2.4.4 Characteristics of current tectonic stresses in the Yucca Mountain region Future igneous intrusion Current tectonic stresses in the region are extensional Future igneous activity will be in the form of dike intrusion BSC 2004, Section 6.3.1 [DIRS 168030] BSC 2003, Section 6 [DIRS 163769] 6.2.4.5 and Attachment IV Boring locations Borings located within or adjacent to the repository footprint BSC2004, Figure 4 [DIRS 168029] Flow characteristics of the Paintbrush nonwelded tuff unit Unit tends to dampen and divert flow due to difference in matrix and fracture characteristics compared to underlying unit BSC 2004, Sections 6.1.2 and 6.2.2 [DIRS 168027] UZ model grid block size Grid block sizes in eastern portion of the repository BSC 2004, Figure 6.1-1 [DIRS 168027] 6.2.4.10 Infiltration rates Range in infiltration rates BSC 2004, Table 6.1-2 [DIRS 168027] FEPs = features, events, and processes, TSPA-LA = total system performance assessment for license application, SZ = saturated zone, UZ = unsaturated zone, YMP = Yucca Mountain Project, IEDs = information exchange drawings, EBS = engineered barrier system, ANL-WIS-MD-000019 REV 01 4-4 April 2004 4.1.2.3 Information Exchange Drawings YMP-prepared drawings or design documents used to provide direct input for System Level FEPs are those shown in Table 4-3. Table 4-3. Drawings Used as Basis for the System Level FEP Evaluations Section Type of Input Value/Contribution Input Source ASSESSMENT BASIS AND MODELING REQUIREMENTS FEPs (Section 6.2.1) (none used) PROCESS AND SITE-CONTROL FEPs (Section 6.2.2) (none used) HUMAN INTRUSION FEPs (Section 6.2.3) (Continued) 6.2.3.9 Overburden thickness from emplacement drift area to topographic surface 215 m 800-IED-WIS0-00101-000-00A BSC 2004 [DIRS 164519] MISCELLANEOUS GEOLOGIC AND ASTRONOMIC FEPs (Section 6.2.4) 6.2.4.5, Attachment IV Overburden thickness from emplacement drift area to topographic surface 215 m 800-IED-WIS0-00101-000-00A BSC 2004 [DIRS 164519] 6.2.4.5, Attachment IV Drift end coordinates for determining area of TSPA-LA Repository Footprint Drift Number and Basis Drift End Coordinate BSC 2004 [DIRS 164519] 6.2.4.5, Attachment IV (3-1W) northernmost drift end N236237 BSC 2004 [DIRS 164519] 6.2.4.5, Attachment IV (2-27) southernmost drift N230944 BSC 2004 [DIRS 164519] 6.2.4.5, Attachment IV (3-2E) easternmost drift end E172231 BSC 2004 [DIRS 164519] 6.2.4.5, Attachment IV (4-20) westernmost drift end E170085 BSC 2004 [DIRS 164519] FEBs = features, events, and processes, TSPA-LA = total system performance for license application 4.1.3 Regulations Used for System Level Feature Event Process Screening (Established Fact) The nature of the FEP screening arguments and TSPA dispositions is such that the NRC regulations (and by incorporation, therein, the corresponding portions of 40 CFR Part 197) serve as direct inputs for determining whether a FEP can be excluded from further considerations. These regulatory inputs are classified as “Established Fact.” No data from technical handbooks or standard references are used as direct input for the System Level FEP evaluations. ANL-WIS-MD-000019 REV 01 4-5 April 2004 Regulatory Basis for Screening FEPs on Low Probability–The application of the low-probability threshold for FEP screening is further described in Section 6.1.2 of this analysis report. For probability, the direct input from the regulatory criterion at 10 CFR 63.114(d) ([DIRS 156605]) is as follows: Consider only events that have at least one chance in 10,000 of occurring over 10,000 years. The EPA provides essentially the same criterion in 40 CFR 197.36 ([DIRS 165519]): The DOE’s performance assessments should not include consideration of very unlikely features, events, or processes, i.e., those that are estimated to have less than one chance in 10,000 of occurring within 10,000 years of disposal. The NRC shall exclude unlikely features, events, and processes, or sequence of processes from the assessments for the human intrusion and ground water protection standards. The specific probability of the unlikely features, events, and processes is to be specified by NRC. As explained in Assumption 5.1, this is assumed equivalent to a 10-8 annual-exceedance probability. Furthermore, for the human intrusion considerations, the NRC at 10 CFR 63.342 ([DIRS 156605] specifically exempts consideration of FEPs with less than one chance in 10 of occurring within the 10,000-year compliance period (i.e., those with an annual exceedance probability of 10-5 or less). Regulatory Basis for Screening FEPs on Low Consequence–The application of the low-consequence arguments for FEP screening is described further in Section 6.1.2 of this analysis report. For low consequence, the direct input from the regulatory criterion at 10 CFR 63.114 (e and f) (66 FR 55732[DIRS 156671]) is as follows: Provide the technical basis for either inclusion or exclusion of specific features, events, and processes in the performance assessment. Specific features, events, and processes must be evaluated in detail if the magnitude and time of the resulting radiological exposures to the reasonably maximally exposed individual, or radionuclide releases to the accessible environment, would be significantly changed by their omission. Provide the technical basis for either inclusion or exclusion of degradation, deterioration, or alteration processes of engineered barriers in the performance assessment, including those processes that would adversely affect the performance of natural barriers. Degradation, deterioration, or alteration processes of engineered barriers must be evaluated in detail if the magnitude and time of the resulting radiological exposures to the reasonably maximally exposed individual, or radionuclide releases to the accessible environment, would be significantly changed by their omission. The EPA provides essentially the same criterion for low consequence at 40 CFR 197.36 ([DIRS 165519]): ANL-WIS-MD-000019 REV 01 4-6 April 2004 In addition, unless specified in NRC regulations, the DOE’s performance assessments need not evaluate, the impacts resulting from any features, events and processes or sequences of events or processes with a higher chance of occurrence if the results of the performance assessments would not be changed significantly. The terms “significantly changed” and “changed significantly” are undefined terms in the NRC and EPA regulations. The absence of significant change if the FEP is omitted is inferred for FEP-screening purposes, to be equivalent to having no effect or negligible effect. Regulatory Basis for Screening FEPs By Regulation–Regulations also address required characteristics, definitions, and concepts, which may serve as the basis for exclusion of FEPs by regulation, as further discussed in Section 4.2. Because the regulatory concepts and definitions are used as part of the technical basis for an exclude decision, the relevant regulatory citations are listed and addressed as direct input, and are listed in Table 4-4 below. By specifying characteristics, concepts, and definitions the regulations serve as de facto inputs used for screening related FEPs. For the System Level FEPs, these criteria include the characteristics, concepts, and definitions pertaining to the reference biosphere, the geologic setting, and the RMEI. Also pertinent are characteristics, concepts, and definitions that must be considered during the FEP screening, such as the areal extent of the accessible environment and of the controlled area, and the spatial relationship between repository and the RMEI. These terms define or imply geographical limits or constrain the consideration of the future state of the reference biosphere and/or geologic setting. The characteristics, concepts, and definitions are listed in Table 4-4, and additional discussion of their application and use follows the table. Table 4-4. Other Direct Input from Regulations Used for the System Level FEP Evaluations Section Type of Input Value/Contribution Input Source ASSESSMENT BASIS AND MODELING REQUIREMENTS FEPs (Section 6.2.1) 10 CFR 63.114(d) 6.2.1.1 Required time period for performance assessment 10,000 years 10 CFR 63.321 10 CFR 63.303 10 CFR 63.305(c) 10 CFR 63.341 [DIRS 156605] 10 CFR 63.312(a) The location is based on the “accessible 10 CFR 63.302 6.2.1.2 Location of the RMEI to define spatial scale of concern environment above the highest concentration of radionuclides in the plume of contamination”. This is located approximately 18 km from the repository above the plume of contamination per the EPA. [DIRS 156605] 40 CFR Part 197 (66 FR 32074, p. 32117 [DIRS 155216] 10 CFR Part 63 10 CFR 63.303 6.2.1.3 Applicable regulations NRC regulations (and EPA regulations as adopted by NRC) [DIRS 156605]), and as incorporated, the requirements of 40 CFR Part 197 [DIRS 165519] ANL-WIS-MD-000019 REV 01 4-7 April 2004 Table 4-4. Other Direct Input from Regulations Used for the System Level FEP Evaluations (Continued) Section Type of Input Value/Contribution Input Source ASSESSMENT BASIS AND MODELING REQUIREMENTS FEPs (Section 6.2.1) (Continued) 6.2.1.4 Model and data requirements Specific elements required for a performance assessment 10 CFR 63,114 (a, b, c, and g) [DIRS 156605] 6.2.1.5 Requirement to provide data and observations on actual and encountered conditions Data and observations related to encountered subsurface conditions, functioning of the natural engineered systems, and monitoring and testing 10 CFR 63.44 10 CFR 63 Subpart F [DIRS 156605] 6.2.1.6 Requirement to allow for retrieval Specific requirements needed to achieve retrievability 10 CFR 63.111(e)(1, 2, 3) [DIRS 156605] PROCESS AND SITE-CONTROL FEPs (Section 6.2.2) 6.2.2.1 and 6.2.2.4 Requirement for use of active and passive institutional controls NRC stated reasoning that long-term reliability of institutional controls can not be reliably forecast 10 CFR 63.102(k) [DIRS 156605] 6.2.2.2 and 6.2.2.5 Requirement to provide data and observations on actual and encountered conditions Data and observations related to: encountered subsurface conditions, functioning of the natural engineered systems, and monitoring and testing 10 CFR 63 Subpart F [DIRS 156605] 6.2.2.2 and 6.2.2.5 Required notification Address modifications and deviations from design 10 CFR 63.44 [DIRS 156605] 6.2.2.2; 6.2.2.5 and 6.2.2.6 Prompt notification if there is a significant deficiency found (1) in the characteristics of the Yucca Mountain site, or (2) in design and construction of the geologic repository area, including significant deviations from the design criteria and design bases stated in the application 10 CFR 63.73(a) [DIRS 156605] 6.2.2.2 Quality control Required quality control program elements and application 10 CFR 63 Subpart G [DIRS 156605] 6.2.2.3 Requirement to address postclosure concerns in the TSPA-LA Preclosure concerns are not the focus of performance assessment 10 CFR 63.102(j) [DIRS 156605] 6.2.2.5 Requirement to conduct a monitoring program Such a monitoring program not adversely affect the repository from meeting performance objectives 10 CFR 63.131(c) 10 CFR 63.131(d)(1) [DIRS 156605] 6.2.2.6 Prompt notification if there is a significant deficiency found Includes requirement for regular audits and inspections 10 CFR 63 Subpart D [DIRS 156605] HUMAN INTRUSION FEPs (Section 6.2.3) 6.2.3.1; 6.2.3.2; 6.2.3.7; 6.2.3.8; and 6.2.3.10 NRC stated intent regarding exposure of intruders and exposure from tailings Should not be considered because it does not show how well a particular repository site and design would protect the public at large 10 CFR Part 63 (Supplementary Information, 3.10 Human Intrusion Standard, p. 55761) (66 FR 55732 [DIRS 156671]) ANL-WIS-MD-000019 REV 01 4-8 April 2004 Table 4-4. Other Direct Input from Regulations Used for the System Level FEP Evaluations (Continued) Section Type of Input Value/Contribution Input Source HUMAN INTRUSION FEPs (Section 6.2.3) (Continued) 6.2.3.1; 6.2.3.2; 6.2.3.7; 6.2.3.8; and 6.2.3.10 NRC requirement regarding which exposure pathways to consider as part of the stylized human intrusion analysis The exposure scenario includes only those radionuclides transported to the saturated zone by water. 10 CFR 63.322(f) [DIRS 156605] 6.2.3.2; 6.2.3.6; and 6.2.3.7 Conditional consideration of effect of human intrusion in TSPA-LA Conditional on lack of recognition of intrusion by intruder prior to 10,000 years If the exposure of the RMEI occurs after 10,000 years, or if the intrusion is projected to occur after 10,000 years, the results of the analysis and the bases of the analysis are to be provided in the environmental impact statement for Yucca Mountain. 10 CFR 63.321 [DIRS 156605] 6.2.3.3 and 6.2.3.4 Unlikely features, events, and processes excluded from consideration as part of the human intrusion assessment Unlikely event defined as those with those that are estimated to have less than one chance in 10 and at least one chance in 10,000 of occurring within 10,000 years of disposal 10 CFR 63.342 [DIRS 156605) 6.2.3.5 Definition of human intrusion Breaching of any portion of the Yucca Mountain disposal system, within the repository footprint, by any human activity 10 CFR 63.302 [DIRS 156605] Conditions for human intrusion stylized analysis Human intrusion only to be evaluated through the specified human intrusion stylized analysis 10 CFR 63.113(d) [DIRS 156605] 6.2.3.6; 6.2.3.7; 6.2.3.8; and 6.2.3.9 Specifications for human intrusion stylized analysis There is a single human intrusion as a result of exploratory drilling for ground water. 10 CFR 63.322 [DIRS 156605] The intruders drill a borehole directly through a degraded waste package into the uppermost aquifer underlying the Yucca Mountain repository. The drillers use the common techniques and practices that are currently employed in exploratory drilling for ground water in the region surrounding Yucca Mountain. 6.2.3.6; 6.2.3.7; 6.2.3.8; and 6.2.3.9 Specifications for human intrusion stylized analysis Careful sealing of the borehole does not occur, instead natural degradation processes gradually modify the borehole. 10 CFR 63.322 [DIRS 156605] No particulate waste material falls into the borehole. The exposure scenario includes only those radionuclides transported to the SZ by water (e.g., water enters the waste package, releases radionuclides, and transports radionuclides by way of the borehole to the SZ). No releases are included which are caused by unlikely natural processes and events. 6.2.3.10 ANL-WIS- Definition of performance assessment MD-000019 REV 01 4-9 Performance assessment is to demonstrate compliance with the postclosure performance objectives April 2004 10 CFR 63.102(j), [DIRS 156605] Table 4-4. Other Direct Input from Regulations Used for the System Level FEP Evaluations (Continued) Section Type of Input Value/Contribution Input Source Preclosure requirements The preclosure requirement is to be based on protection of the RMEI against radiation exposures and releases of radioactive material 10 CFR 63.311(a), [DIRS 156605] MISCELLANEOUS GEOLOGIC AND ASTRONOMIC FEPs (Section 6.2.4) 6.2.4.3; 6.2.4.4; and 6.2.4.9 Definition of geologic setting Defined as the geologic, hydrologic, and geochemical systems of the region in which the geologic repository is or may be located 10 CFR 63.2 [DIRS 156605] FEPs required to be considered Consideration and description of “features, events, and processes outside of the site to the extent the information is relevant and material to safety or performance of the geologic repository. (Evaporite deposits are absent and stress regime is extensional and not conducive to diapirism) 10 CFR 63.21(c)(1) [DIRS 156605] Data requirements and identifying barriers are addressed “Include data that are related to the geology, hydrology, and geochemistry (including disruptive events) of the Yucca Mountain Site, and the surrounding region to the extent necessary …” and to “identify … natural features of the geologic setting, that are considered barriers important to waste isolation” 10 CFR 63.114(a); 10 CFR 63.115(a) [DIRS 156605] 6.2.4.3; 6.2.4.4; and 6.2.4.9 Requirement that assumptions must be consistent with present knowledge Vary factors related to the geology, hydrology, and climate based upon cautious, but reasonable assumptions consistent with present knowledge of factors that could affect the Yucca Mountain disposal system over the next 10,000 years 10 CFR 63.305(c) [DIRS 156605] 6.2.4.10 Requirements that changes in the biosphere should not be projected DOE should not project changes in society, the biosphere (other than climate), human biology, or increases or decreases of human knowledge or technology. In all the analyses done to demonstrate compliance with this part, DOE must assume that all of those factors remain constant as they are at the time of submission of the license 10 CFR 63.305(b) [DIRS 156605] application. The definition of reference biosphere Specifically identifies flora as being a component of the reference biosphere 10 CFR 63.2 (66 FR 55732 [DIRS 156671]) DOE = U.S. Department of Energy, EPA = U.S. Environmental Agency, FEPs = features, events, and processes, NRC = U.S. Nuclear Regulatory Commission, RMEI = reasonably maximally exposed individual, SZ= saturated zone, TSPA-LA = total system performance assessment for license applicable ANL-WIS-MD-000019 REV 01 4-10 April 2004 RMEI–The characteristics of the RMEI to be used in exposure calculations are given at 10 CFR 63.312 (a, b, c, d, and e) ([DIRS 156605] and at 40 CFR 197.21(a, b, and c) ([DIRS 165519])). Conceptually, the RMEI is described at 10 CFR 63.102(j) [DIRS 156605]: The reasonably maximum exposed individual, as a hypothetical person living in a community with characteristics of the Town of Amargosa Valley, is a representative person using water with average concentrations of radionuclides as described at §63.312. Characteristics of the reference biosphere and the reasonably maximally exposed individual are to be based on current human behavior and biospheric conditions in the region, as described in §63.305 and §63.312. For completeness and explanation, the required characteristics of the reference biosphere are given in 10 CFR 63.305 [DIRS 156605] and are addressed separately below. For purposes of this analysis report, the pertinent required characteristics of the RMEI, as described at 10 CFR 63.312(a) and (b) [DIRS 156605] is that the RMEI: Lives in the accessible environment above the highest concentration of radionuclides in the plume of contamination. and: Has a diet and living style representative of the people who now reside in the Town of Amargosa Valley, Nevada. From 10 CFR 63.302 [DIRS 156605] and at 40 CFR 197.12 [DIRS 165519]: Accessible environment means any location outside the controlled area. Moreover, the controlled area is: The surface area, identified by passive institutional controls, that encompasses no more than 300 square kilometers. It must not extend farther: South than 36° 40' 13.6661. north latitude, in the predominant direction of ground water flow; and Than five kilometers from the potential repository footprint in any other direction; and The subsurface underlying the surface area. The preamble in the regulations for 40 CFR Part 197 (66 FR 32074, p. 32117 [DIRS 155216]) states further that: If fully employed by DOE, and based on current repository design, the controlled area could extend approximately 18 km in the direction of ground water flow ANL-WIS-MD-000019 REV 01 4-11 April 2004 (presently believed to be in a southerly direction) and extend no more than 5 km from the repository footprint in any other direction. Furthermore, the NRC states in the preamble to 10 CFR Part 63 (66 FR 55732, p. 55753 [DIRS 156671]) that: At distances less than 18 km to the Yucca Mountain site, there is evidence of intermittent or temporary occupation in modern (historic) times in and around the site—for prospecting or ranching. There also are a number of Native American archeological sites reported throughout NTS closer to the site than the Lathrop Wells location. However, the literature indicates that these were never permanently occupied, and most were abandoned by the end of the 1800’s. Overall, the literature suggests many reasons for the absence of permanent inhabitation at distances much closer than 18 km to the site - unfavorable agricultural conditions, inhospitable terrain, the scarcity of mineral resources, and limitations on water availability. These definitions and concepts indicate that the RMEI is located no closer than 18 km to the south in the direction of groundwater flow and over a contaminated groundwater plume (in accordance with 10 CFR 63.312 (a, b, c, d, and e) [DIRS 156605]), and that the limit of the controlled area is no greater than 5 km from the repository in any other direction (as specified at 10 CFR 63.302 [DIRS 156605]). These concepts, definitions, and required characteristics are pertinent because the location of the RMEI and the associated distance from the repository is of primary interest in evaluating potential exposure risk due to potential releases at the repository. The location of the RMEI is also of importance for determining exposure and is part of the technical basis for included FEPs. The location and characteristics of the RMEI for the nominal scenario class are also used for the disruptive scenario classes. Reference Biosphere and Geologic Setting–Per 10 CFR 63.2 ([DIRS 156605]), the “reference biosphere” is defined as: Reference biosphere means the description of the environment inhabited by the reasonably maximally exposed individual. The reference biosphere comprises the set of specific biotic and abiotic characteristics of the environment, including, but not necessarily limited to, climate, topography, soils, flora, fauna, and human activities. Characteristics pertaining to the reference biosphere are presented in 10 CFR 63.305(a) and (b) ([DIRS 156605]). (a) Features, events, and processes that describe the reference biosphere must be consistent with present knowledge of the conditions in the region surrounding the Yucca Mountain site. (b) DOE should not project changes in society, the biosphere (other than climate), human biology, and increase or decreases of human knowledge or technology. In all analyses done to demonstrate compliance with this part, ANL-WIS-MD-000019 REV 01 4-12 April 2004 DOE must assume that all those factors remain constant as they are at the time of license application. The evolution of the reference biosphere and the geologic setting are linked by the NRC at 10 CFR 63.305(c) [DIRS 156605]; also by the EPA at 40 CFR 197.15 ([DIRS 165519])). (c) DOE must vary factors relating to the geology, hydrology, and climate, based upon cautious, but reasonable assumptions, consistent with present knowledge of factors that could affect the Yucca Mountain disposal system in the next 10,000 years. (The EPA language varies slightly by stating “the changes in these factors,” in contrast to the NRC language of “consistent with present knowledge of factors.”) Per 10 CFR 63.2 [DIRS 156605]), the geologic setting is defined as: The geologic, hydrologic, and geochemical systems of the region in which a geologic repository is or may be located. By NRC’s juxtaposition of the geologic and hydrologic factors within the subsection addressing required characteristics of the reference biosphere, it is inferred that the listed regulatory constraint of changes in the reference biosphere may also be applicable to conditions that may occur at Yucca Mountain. This approach agrees with the statement at 10 CFR 63.102(i) ([DIRS 156605]) that: Characteristics of the reference biosphere and the reasonably maximally exposed individual are to be based on current human behavior and biospheric conditions in the region, as described in §63.305 and §63.312. Specifically identified in the definition of the referenced biosphere are changes to soil, topography, and flora. The application of this regulatory input specifically indicates that characteristics of the reference biosphere are to be based on biospheric conditions in the region. The restriction on consideration of changes in flora is applicable to discussions in Section 6.2.4.10 dealing with potential changes in ecological factors due to repository heat and provides a regulatory basis for excluding the consideration of changes. Institutional Control–The regulatory definition of the controlled area and the associated resulting geographic boundaries are previously described within the discussions of the concept of the RMEI. At 10 CFR 63.102(k) ([DIRS 156605]), the regulations address the use of institutional controls. The regulations require that the use of both passive and active institutional controls are to be maintained, and recognizes that they are expected to reduce significantly, but not eliminate, the potential for human activity that causes or accelerates the release of radioactive material. To eliminate further speculation on how to address the effectiveness of these controls the cited regulations state: However, because it is not possible to make scientifically sound forecasts of the long-term reliability of institutional controls, it is not appropriate to include consideration of human intrusion into a fully risk-based performance assessment ANL-WIS-MD-000019 REV 01 4-13 April 2004 for purposes of evaluating the ability of the geologic repository to achieve the performance objective… Accordingly, for those FEPs addressing administrative controls, and particularly their influence on the timing of human intrusion, the FEPs have been excluded, by regulation, from consideration in the human intrusion stylized analysis. Human Intrusion–Human intrusion is defined at 10 CFR 63.302 ([DIRS 156605]) and 40 CFR 197.12 ([DIRS 165519]) as: Human intrusion means breaching any portion of the Yucca Mountain disposal system, within the repository footprint, by any human activity. This is an important concept in that “any” human activity that has the potential to breach the disposal system is included within the regulatory intent regarding human intrusion. By way of clarification, in 10 CFR 63.2 ([DIRS 156605]), the term “performance assessment” is defined as an analysis that: Identifies the features, events, and processes (except human intrusion), and sequences of events and processes (except human intrusion), that might affect the Yucca Mountain disposal system and their probabilities of occurring during 10,000 years after disposal. From this statement stems a regulatory basis for excluding all System Level FEPs that address human intrusion from consideration in the TSPA–LA model. However, there are also specific regulatory provisions regarding consideration of human intrusion. At 10 CFR 63.322 ([DIRS 156605]), the NRC states that: For the purposes of the analysis of human intrusion, DOE must make the following assumptions: (a) There is a single human intrusion as a result of exploratory drilling for ground water; (b) The intruders drill a borehole directly through a degraded waste package into the uppermost aquifer underlying the Yucca Mountain repository; (c) The drillers use the common techniques and practices that are currently employed in exploratory drilling for ground water in the region surrounding Yucca Mountain; (d) Careful sealing of the borehole does not occur, instead natural degradation processes gradually modify the borehole; (e) No particulate waste material falls into the borehole; ANL-WIS-MD-000019 REV 01 4-14 April 2004 (f) The exposure scenario includes only those radionuclides transported to the saturated zone by water (e.g., water enters the waste package, releases radionuclides, and transports radionuclides by way of the borehole to the saturated zone; and (g) No releases are included which are caused by unlikely natural processes and events. This is similar to the requirements in 40 CFR 197.26 ([DIRS 165519]), except that the EPA regulations do not specify item (e) above, and item (f) is replaced with the following language at 40 CFR 197.26 (e) ([DIRS 165519]): Only releases of radionuclides that occur as a result of the intrusion and that are transported through the resulting borehole to the SZ are projected; Several concepts in this set of regulations are important to the evaluation of human intrusion FEPs and are listed as direct input. First, rather than speculating on the nature and probability of future intrusion, the NRC has required that human intrusion be evaluated via a human intrusion stylized analysis. This is emphasized in the regulations at 10 CFR 63.322 (66 FR 55732 [DIRS 156671]) with the statement that “DOE must make the following assumptions…”,which define the human intrusion stylized analysis. . Additionally, the preamble to 10 CFR Part 63 (66 FR 55732 [DIRS 156671], Supplementary information, 3.10 Human Intrusion Standard, p. 55761) indicates that the NRC intended the analysis to be based on a stylized analysis. With regard to the timing of the human intrusion, the use of both active and passive institutional controls (such as markers and an information repository) will reduce the potential for future human activity. However, it is not possible to make scientifically sound forecasts of the long-term reliability of such controls as previously discussed under institutional controls. Accordingly, at 10 CFR 63.321 ([DIRS 156605]), the NRC specifies the criteria under which human intrusion must be evaluated: DOE must determine the earliest time after disposal that the waste package would degrade sufficiently that a human intrusion could occur without recognition by the drillers. Furthermore, by way of explanation and corroboration, per 10 CFR 63.321(a) ([DIRS 156605]), DOE must: Provide the analyses and its technical bases used to determine the time of occurrence of human intrusion (see 10 CFR 63.322) without recognition by the drillers. Also, by way of explanation and corroboration, if the waste package penetration is projected to occur before or at the 10,000-year performance period, then the DOE is to provide a demonstration per 10 CFR 63.321(b)(1) ([DIRS 156605]) that: …there is a reasonable expectation that the reasonably maximally exposed individual receives no more than an annual dose of 0.15 milliSieverts (mSv) ANL-WIS-MD-000019 REV 01 4-15 April 2004 (15 mrem) as a result of a human intrusion, at or before 10,000 years after disposal. And, by way of explanation and corroboration, per 10 CFR 63.321(b)(2) ([DIRS 156605]): If the exposure of the RMEI occurs after 10,000 years, or if the intrusion is projected to occur after 10,000 years, the results of the analysis and the bases of the analysis are to be provided in the environmental impact statement for Yucca Mountain. Additionally, the specifications at 10 CFR 63.322(f) ([DIRS 156605]) and at 40 CFR 197.26(e) ([DIRS 165519])), indicating that only radionuclides transported to the saturated zone be considered, preclude the consideration of FEPs related to the exposure of the public, drillers, or other human intruders from cuttings, circulated materials, or tailings. The preamble to 10 CFR Part 63 (66 FR 55732 [DIRS 156671], Supplementary information, 3.10 Human Intrusion Standard) is clear about the intent of the NRC: Human intrusion has the potential for releasing particulate HLW to the surface with drill cuttings or providing a fast pathway for radionuclides to be transported to the SZ by water (e.g., water enters the waste package, releases radionuclides, and transports radionuclides by way of the borehole to the SZ). NAS concluded, and the Commission agrees, that analysis of the risk to the public or the intruders (i.e., drilling crew) from radioactive drill cuttings left unattended at the surface for subsequent dispersal into the biosphere would not fulfill the purpose of the human intrusion calculation because it would not show how well a particular repository site and design would protect the public at large. Rather, an analysis of the hazard of particulate high-level waste (HLW) left on the surface would be dominated by assumptions subject to significant speculation and uncertainty regardless of the particular site or design under evaluation. Additionally, the release to the surface represents a one-time release with no long-term effect on the repository barriers. With regard to the motivation of a human intrusion being intentional/deliberate or inadvertent/ accidental, the regulations at 10 CFR Part 63 ([DIRS 156605]) is silent. Similarly, the regulations at 40 CFR Part 197 ([DIRS 165519]) do not directly address the motivation or intentionality of the intrusion. However, the NRC states in the preamble to 10 CFR Part 63 (66 FR 55732 [DIRS 156671], p. 55753) that: Overall, the literature suggests many reasons for the absence of permanent inhabitation at distances much closer than 18 km to the site—unfavorable agricultural conditions, inhospitable terrain, the scarcity of mineral resources, and limitations on water availability. This suggests that the motives for a human intrusion are not likely to be economically motivated given knowledge of present conditions, and adds support for use of a human intrusion stylized analysis. The supplemental discussions for 40 CFR Part 197 (66 FR 32074 [DIRS 155216]) clarify that consideration of deliberate intrusion is not intended. In the preamble to 40 CFR Part 197 ANL-WIS-MD-000019 REV 01 4-16 April 2004 (66 FR 32074, Item 3 “What is the Standard for Human Intrusion?” p. 32105 [DIRS 155216]), the EPA, in response to comments regarding the human intrusion stylized analysis, states: Comments we received proposing alternative drilling frequencies and intentions, such as deliberately drilling into the repository, did not provide a sufficient rationale to abandon the NAS recommendations and we therefore retained our original framing for the scenario. The EPA amplifies this in the preamble to 40 CFR Part 197 (66 FR 32074, p. 32127, more specifically Item 10, “Is the Single–Borehole Scenario a Reasonable Approach to Judge the Resilience of the Yucca Mountain Disposal System Following Human Intrusion?” [DIRS 155216]). The EPA explicitly states that: Some comments suggested that there is a strong possibility for deliberate intrusion into the repository to access its content as possible resources. We believe that there is no useful purpose to assessing the consequences of deliberate intrusions because in that case the intruders would be aware of the risks and consequences and would have decided to assume the risks. This is consistent with NAS’s conclusion regarding intentional intrusion (NAS Report, p. 14). Consequently, all deliberate human intrusion FEPs discussed in this analysis report are excluded based on the regulatory intent, and all inadvertent intrusions are considered within the context of the regulatory requirements. The requirement is to consider only the stylized human intrusion (i.e., based on drilling techniques related to groundwater use) and the timing of such an event, regardless of the specific motivation or intentionality of the intruders. 4.1.4 Other “Not Site-Specific” Data from Non-Yucca Mountain Project Sources (Data) For the System Level FEPs, the majority of the direct input is in the form of data taken from non- project sources. The nature of the FEP screening arguments and TSPA dispositions is such that other direct input and data are cited extensively to support reasoned FEP screening arguments or TSPA dispositions. As needed, other non-YMP data sources, alternative conceptual models, and references were obtained from literature searches of peer-reviewed journals, other widely recognized scientific periodicals, and results of review of YMP documents by external organizations. The procedure governing the management of direct inputs allows the use of such references as data, but requires that the basis and justification for use be provided within the citing AMR. These additional sources of information are shown in Table 4-5, and data qualification activities are addressed in Attachment II. ANL-WIS-MD-000019 REV 01 4-17 April 2004 Table 4-5. Data from Non-YMP Sources Used for the System Level FEP Evaluations Section Type of Input Value/Contribution Input Source ASSESSMENT BASIS AND MODELING REQUIREMENTS FEPs (Section 6.2.1) (none used) PROCESS AND SITE-CONTROL FEPs (Section 6.2.2) (none used) HUMAN INTRUSION FEPs (Section 6.2.3) 6.2.3.2, 6.2.3.6, 6.2.3.7 and Attachments II and III Relation of compressive strength to penetration rate Rate of penetration ranges from inversely proportional to the square of the compressive strength of the material being drilled, to inversely proportional, all other factors being equal Bourgoyne et al. 1986, Equation 5-19 [DIRS 155233]; Kahraman et al. 2000, Equation 8 [DIRS 167761] Energy release required to fracture or exhume to various depths of interest. 1012 to 1017 Joules (200 to 20 megaton TNT equivalent) Dence et al. 1977, Figure 12 [DIRS 135253] Various energy releases associated with airplane crashes Kinetic energy of a Boeing 767 is on the order of 1 to 2 tons TNT Energy from a Tomahawk cruise missile is on the order of 0.5 ton Stix and Yam 2001, p. 15 [DIRS 160994] Energy yield from conventional weapons Conventional yield of a GBU-28 “bunker buster” bomb is on the order of 2 tons Ferguson 2002 [DIRS 160988] Backman and 6.2.3.9 and Attachment II Goldsmith 1978, pp. 33, 38, Equation 6.2 [DIRS 167628] Maximum penetration depth of ground penetrating weapons Reported penetration depths Forrestal et al. 1981, p. 28[DIRS 167630] Patterson 1974, [DIRS 167805] Young 1976, Table II [DIRS 167806] Radial effects from underground nuclear blasts In the 64-kt Pile Driver test, stresses at about 100 m (328 feet) were slightly less than that needed to propagate fractures in granodiorite Dence et al. 1977, p. 262 [DIRS 135253] ANL-WIS-MD-000019 REV 01 4-18 April 2004 Table 4-5. Data from Non-YMP Sources Used for the System Level FEP Evaluations (Continued) Section Type of Input Value/Contribution Input Source MISCELLANEOUS GEOLOGIC AND ASTRONOMIC FEPs (Section 6.2.4) 6.2.4.1 and Attachment II Conditions needed for regional metamorphism T>150-200°C at pressures on the order of a 0.5-1 kilobars, and depths of 4-5 kms Ehlers and Blatt 1972, p. 566 [DIRS 167802] Value for pressure gradients from geostatic loading Approximately 0.6 kbar per km Ehlers and Blatt 1972, p. 169, Figure 6-3 [DIRS 167802] Value for temperature gradients Approximately 10 to 25° C per km Ehlers and Blatt 1972, pp. 684-685 [DIRS 167802] Time required for complete naturally occurring diagenesis in the shallow environment The time required for complete diagenesis in the shallow environment (extending from the surface to the downward limit of evapotranspiration) is potentially within the timescale of concern for the repository performance assessment Lattman and Simonberg 1971, p. 277 [DIRS 129306] Krystinik 1990, p. 8-1 [DIRS 135295] CaCO3 and SiO2 exhibit distinctive trends that correspond with ages of surficial deposits, but SiO2 cementation is not dependent on climatic conditions Relationship of Diagenesis to Climate Accumulation rates are attributable to several climatic scenarios, but climate change was insufficient to significantly decrease the rate of accumulation Taylor 1986, Chapter 5 [DIRS 102864] 6.2.4.2 and Attachment II Modeling suggests that CaCO3 may translocate to greater depths with greater precipitation. Initial compaction can reduce porosity by Compaction during diagenesis 20 to 30 percent. Compaction does not generally become an important factor in diagenesis until the onset of grain deformation and pressure solution during Krystinik 1990, pp. 8-3, 8-4 [DIRS 135295] deeper burial diagenesis Cementation during diagenesis The net effect of shallow diagenesis is to stabilize the surface environment and decrease the net vertical infiltration rate Accumulation rate for Yucca Mountain alluvium favors SiO2 over CaCO3. CaCO3 is an accessory cement and cementation process is reversible Cementation by calcium carbonate is not a significant process in rhyolitic tuffs due to the lack of carbonate source material Cements other than from carbonate may develop Reeves 1976, p. 110 [DIRS 104303] Taylor 1986, pp. 31-33, Figure 9, Chapter 5 [DIRS 102864] Lattman 1973, p. 3015 [DIRS 129305] Krystinik 1990, p. 8-4 [DIRS 135295] ANL-WIS-MD-000019 REV 01 4-19 April 2004 Table 4-5. Data from Non-YMP Sources Used for the System Level FEP Evaluations (Continued) Section Type of Input Value/Contribution Input Source MISCELLANEOUS GEOLOGIC AND ASTRONOMIC FEPs (Section 6.2.4) (Continued) Ceplecha 1992, Flux data for a range of meteor masses p. 362, Figure 1 [DIRS 135242] Flux data by meteor type and related densities Ceplecha 1994, p. 967: Tables 1, 3, and 4; Figure 2, Table 4 [DIRS 135243] Subsurface spatial relationships and energy/distance relationships resulting in crater formation Dence et al. 1977, pp. 250 and 261–264 [DIRS 135253] Crater rate distribution based on observed Grieve 1987, earth cratering and diameters associated pp. 249, 257, Figure 8 6.2.4.5 Appendices II and IV Meteorite input data with onset of complex cratering [DIRS 135254] Provides results of a model that link a variety of effects to initial meteor radius, including resulting crater diameters and related consequences Hills and Goda 1993, pp. 1140 and 1142, Figures 9, 16, 17, and 18 [DIRS 135281] Values for percent of meteors that are of iron composition Shoemaker 1983, pp. 464 and 480 [DIRS 135308] Spatial relationship of crater diameter to extents and depth of fracturing and exhumation and crater diameters associated with onset of complex cratering Wuschke et al. 1995, p. 3 [DIRS 129326] Spatial extent of fracturing is assumed to be spherical Wuschke et al. 1995, Figure 1 [DIRS 129326] Crater diameters associated with onset of Grieve et al. 1995, complex cratering p. 184 [DIRS 135260] Crater diameter to depth of effect relationships Grieve 1998, p. 113, Figure 8 [DIRS 163385] Provides cratering rate data for the Canadian shield and application to a hypothetical Canadian repository Wuschke et al. 1995,pp. 4 and 26 [DIRS 129326] ANL-WIS-MD-000019 REV 01 4-20 April 2004 Table 4-5. Data from Non-YMP Sources Used for the System Level FEP Evaluations (Continued) Section Type of Input Value/Contribution Input Source MISCELLANEOUS GEOLOGIC AND ASTRONOMIC FEPs (Section 6.2.4) (Continued) 6.2.4.6, Attachment II Effects of Non-Solar Extraterrestrial Events Frequency of events is on the order of 1 event per 100 years Energy released from such events is on the order of 1050 ergs Effects may have included creation of a nitrogen-rich environment, short-term global cooling, and ozone depletion No subsurface effects were mentioned or discussed Brakenridge 1981 [DIRS 167873] Solar-related Effects There are numerous associations between solar variability and terrestrial parameters that range from the earth’s surface to hundreds of kilometers above it, on the time scales from days to centuries. These include relations between decadal sun cycles and earth’s surface temperature, overall solar activity with earth’s surface temperature, and possible links from changes in IR and visible and IR radiation to changes in earth’s temperature and climate Lean 1997 [DIRS 167639] Uses of space weather prediction; discussion of the type of operations affected and problems encountered List of engineered systems and operations that could experience problems due to space weather Maynard 1995 [DIRS 160888] 6.2.4.7, Attachment II Evidence for changes and fluctuations in the earth’s magnetic field During the last 20 million years, the fossil record shows at least 60 reversals, and the periodicity of the reversal is on the scale of a few hundred thousand years to once every million years Odenwald 2003 [DIRS 160892] Changes in the earth’s magnetic intensity in the past and prediction for the future There has been a decrease in the earth’s magnetic intensity in the last few thousand years, and there is some evidence that a reversal in the earth’s magnetic field may occur sometime during the next few to several thousand years Odenwald 2003 [DIRS 160892] Effects of magnetic field changes on natural systems No identifiable fossil effects such as mutation or extinctions. Odenwald 2003 [DIRS 160892] 6.2.4.8, Attachment II Tidal force effects on water levels at Yucca Mountain Water level fluctuations in well UE-25 pl is cited from others as 2.05 cm Bredehoeft 1987, p. 2460 [DIRS 100007] FEPs = features, events, and processes ANL-WIS-MD-000019 REV 01 4-21 April 2004 4.2 CRITERIA This section addresses the criteria relevant to the FEP screening process. These criteria were not presented in the TWP because they were not identified until after preparation of the TWP during review of the Project Requirements Document (PRD) (Canori and Leitner 2003 [DIRS 166275]) and during preparation of this analysis report. These criteria stem from the applicable regulations at 10 CFR Part 63 [DIRS 156671] (and also those incorporated from 40 CFR Part 197 [DIRS 155216]), as identified in the PRD. These criteria find expression as specific acceptance criteria presented by the NRC in NUREG-1804 (NRC 2003 [DIRS 163274]). The correlation of the regulations and criteria are shown in Table 4-6, and applications of the criteria for FEP screening are described in Section 4.1.3.1 of this analysis report. The PRD (Canori and Leitner 2003 [DIRS 166275]) documents and categorizes the regulatory requirements and other project requirements and provides a crosswalk to the various YMP organizations that are responsible for ensuring that the criteria have been addressed in the LA. The regulatory requirements include criteria relevant to performance assessment activities, in general, and to FEP-related activities as they pertain to performance assessment, in particular. Table 4-6 provides a crosswalk between the regulatory requirements, the PRD (Canori and Leitner 2003 [DIRS 166275]), and the acceptance criteria provided in NUREG-1804 (NRC 2003, Sections 2.2.1.2 and 2.2.1.4 [DIRS 163274]). The NRC will be reviewing the LA. The basis of the review is described in NUREG-1804 (NRC 2003, Sections 2.2.1.2 [DIRS 163274]), and the bases for acceptance are stated as acceptance criteria. In Table 4-6, NUREG-1804 acceptance criteria are correlated to the corresponding regulations and related PRDs as they pertain to FEP-related criteria. With only a few exceptions, the regulatory requirements at 40 CFR Part 197 ([DIRS 165519]) have been incorporated within the requirements of 10 CFR Part 63 ([DIRS 156605]). However, because the EPA regulations at 40 CFR Part 197 ([DIRS 165519]) have not been superseded, this analysis report has, for completeness, retained EPA citations in the individual FEP discussions as needed for clarity. In a few instances, differences in the regulations also are cited to clarify a particular FEP concept, definition, or approach to a screening argument. The cited NUREG-1804 criteria are provided in Table 4-7. The acceptance criteria for FEP screening presented in the NUREG-1804echo the screening criteria of low probability and low consequence (NRC 2003 Section 2.2.1.2.1.3 Acceptance Criterion 2 Screening of the Initial List of Features, Events, and Processes Is Appropriate [DIRS 163274]) but also allow for exclusion of a FEP if the process is specifically excluded by the regulations. To wit: The U.S. Department of Energy has justified excluding each feature, event, and process. An acceptable justification for excluding features, events, and processes is that either the feature, event, and process is specifically excluded by regulation; probability of the feature, event, and process (generally an event) falls below the regulatory criterion; or omission of the feature, event, and process does not significantly change the magnitude and time of the resulting radiological exposures to the reasonably maximally exposed individual, or radionuclide releases to the accessible environment. ANL-WIS-MD-000019 REV 01 4-22 April 2004 The application of the FEP screening criteria is described further in Section 6.1.2 of this analysis report. The regulatory criteria for determining low probability or low consequence, and the characteristics, definitions and concepts used to screen FEPs based on the regulations, are listed in Section 4.1.3.1 as Direct Input. Table 4-6. Relationships of EPA and NRC Regulations to the PRD and to the Acceptance Criteria from the NUREG-1804 Description of the Applicable Regulatory Requirement or Acceptance Criterion 40 CFR Part 197 [DIRS 165519] 10 CFR Part 63 [DIRS 156605] Canori and Leitner 2003 [DIRS 166275] Associated Criteria in NUREG-1804 [DIRS 163274] Regulatory Citation Regulatory Citation Associated PRD General Requirements and Scope Pertinent to FEP Screening Include data related to geology, hydrology, geochemistry, and geophysics Not Applicable 63.114(a) PRD-002/ T-015 2.2.1.2.1.3 Acceptance Criterion 1 Include information of the design of the engineered barrier system used to define parameters and Not Applicable 63.114(a) PRD-002/ T-015 2.2.1.2.1.3 Acceptance Criterion 1 conceptual models Account for uncertainties and variabilities in parameter values and provide the technical basis for parameter ranges, probability distributions, or 197.14 63.114(b) PRD-002/ T-015 2.2.1.2.2.3 Acceptance Criteria 2 and 5 bounding values FEP Screening Criteria Provide the justification and technical basis for 2.2.1.2.1.3 excluding FEPs specifically excluded by Not Applicable Not Applicable Not Applicable Acceptance Criterion 2 regulation. 2.2.1.2.1.3 Provide the technical basis for either inclusion or exclusion of FEPs. Provide 63.114(d) PRD-002/ T-015 Acceptance Criterion 2 the justification and technical basis for those 197.36 2.2.1.2.2.3 excluded based on probability. 63.342 PRD-002/ T-034 Acceptance Criteria 1 and 2 Provide the technical basis for either inclusion or exclusion of FEPs. Provide the justification and the technical basis for those excluded based on lack of significant change in resulting radiological exposure or release to the accessible environment. 197.36 63.114 (e and f) 63.342 PRD-002/ T-015 PRD-002/ T-034 2.2.1.2.1.3 Acceptance Criterion 2 2.2.1.2.2.3 Acceptance Criteria 1 and 2 ANL-WIS-MD-000019 REV 01 4-23 April 2004 Table 4-6. Relationships of EPA and NRC Regulations to the PRD and to the Acceptance Criteria from NUREG-1804 (Continued) Description of the Applicable Regulatory Requirement or Acceptance Criterion 40 CFR Part 197 [DIRS 165519] 10 CFR Part 63 [DIRS 156605] Canori and Leitner 2003 [DIRS 1662754] Associated Criteria in NUREG-1804 [DIRS 163274} Regulatory Citation Regulatory Citation Associated PRD General Requirements and Scope Pertinent to FEP Screening Human Intrusion Criteria Time of earliest penetration without recognition and basis 197.25 63.321 PRD-002/ T-029 2.2.1.4.2.3 Acceptance Criterion 1 Treatment if human intrusion results in RMEI exposure prior to 10,000 years 197.25(a) 63.321(b)(1) PRD-002/ T-029 2.2.1.4.2.3 Acceptance Criterion 2 Treatment if human intrusion results in RMEI exposure post- 10,000 years 197.25(b) 63.321 (b)(2) PRD-002/ T-029 2.2.1.4.2.3 Acceptance Criterion 2 Required circumstances/ assumptions for human intrusion analysis 197.26 63.322 (a, b, c, d, e) PRD-002/ T-030 2.2.1.4.2.3 Acceptance Criterion 2 Consideration only via groundwater pathway 197.26(e) 63.322(f) PRD-002/ T-030 2.2.1.4.2.3 Acceptance Criterion 2 No consideration of unlikely processes in combination with human intrusion 197.26(f) 63.322(g) PRD-002/ T-030 2.2.1.4.2.3 Acceptance Criterion 2 FEPs = features, events, and processes, PRD = Project Requirements Document, RMEI = reasonably maximally exposed individual, ANL-WIS-MD-000019 REV 01 4-24 April 2004 Table 4-7. NUREG-1804 Criteria and the System Level FEPs AMR NUREG-1804 Criterion Acceptance Criterion Description How Addressed in this Analysis Report Scenario 1. The Identification of a list of FEPs Is Adequate The safety analysis report contains a complete list of FEPs related to the geologic setting or the degradation, deterioration, or alteration of engineered barriers (including those processes that would affect the performance of natural barriers), that have the potential to influence repository performance. The list is consistent with the site characterization data. Moreover, the comprehensive features, events, and processes list includes, but is not limited to, potentially disruptive events related to igneous activity (extrusive and intrusive); seismic shaking (high- frequency-low magnitude, and rare large-magnitude events); tectonic evolution (slip on existing faults and formation of new faults); climatic change (change to pluvial conditions); and criticality. The list of System Level FEPs is provided in Section 1.2, and FEP Descriptions are provided in Section 6.2. See Section 6.1.1 of this analysis report for a description and origin of the System Level FEP list and descriptions. This analysis report does not address disruptive events or climatic change. Analysis and Event Probability: Scenario The DOE has identified all FEPs related to either the geologic setting or to the degradation, deterioration, or alteration of engineered barriers (including those processes that would affect the performance of natural barriers) that have been excluded. See Table 7-1 for a list of excluded System Level FEPs. Analysis (from Section 2.2.1.2.1.3 NUREG-1804 [DIRS 163274]) 2. Screening of the Initial List of Features, Events, and Processes Is Appropriate The DOE has provided justification for those FEPs that have been excluded. An acceptable justification for excluding FEPs is that either the FEP is specifically excluded by regulation; probability of the FEP (generally an event) falls below the regulatory criterion; or omission of the feature, and process does not significantly change the magnitude and time of the resulting radiological exposures to the reasonably maximally exposed individual, or radionuclide releases to the accessible environment. See the method and approach discussion provided in Section 6.1.2 and the individual justification (by regulation, low probability, low consequence) for excluding FEPs. The justification is also included in Table 7-1. The DOE has provided an adequate technical basis for each FEP, excluded from the performance assessment, to support the conclusion that either the FEP is specifically excluded by regulation; the probability of the FEP falls below the regulatory criterion; or omission of the FEP does not significantly change the magnitude and time of the resulting radiological exposures to the reasonably maximally exposed individual, or radionuclide releases to the accessible environment. See Section 6.2 for discussion of the individual FEP depositions and supporting technical bases. ANL-WIS-MD-0000019 REV 01 4-25 April 2004 Table 4-7. NUREG-1804 Criteria and the System Level FEPs AMR (Continued) NUREG-1804 Criterion Acceptance Criterion Description How Addressed in this Analysis Report Events or event classes are defined without ambiguity and used consistently in probability models, such that probabilities for each event or event class are estimated separately. See the FEP Description provided for each FEP in Section 6.2 and the cited supporting AMRs. 1. Events are Scenario Analysis and Event Probability: Adequately Defined Probabilities of intrusive and extrusive igneous events are calculated separately. Definitions of faulting and earthquakes are derived from the historical record, paleoseismic studies, or geological analyses. Criticality events are calculated separately by location. This analysis report does not address igneous, seismic or criticality FEPs. This criterion is not applicable to this analysis report. Identification of Events with Probability Greater than 10-8 per Year 2. Probability Estimates for Future Events Are Supported by Appropriate Technical Bases. Probabilities for future natural events are based on past patterns of the natural events in the Yucca Mountain region, considering the likely future conditions and interactions of the natural and engineered repository system. These probability estimates have specifically included igneous events, faulting and seismic events, and criticality events. Other future naturally occurring events (such as meteorite impact) are addressed in this analysis report. See FEP discussions in Section 6.2.4 for a list of naturally occurring FEPs that are addressed. This analysis report does not address igneous, seismic or criticality FEPs (from Section 2.2.1.2.2.3 NUREG-1804 [DIRS 163274]) 5. Uncertainty in Event Probability is Adequately Evaluated Probability values appropriately reflect uncertainties. Specifically: a. The DOE provides a technical basis for probability values used, and the values account for the uncertainty in the probability estimates: and The technical basis and discussion of uncertainties used for exclusion of System-Level FEPs are discussed in the subsections of Section 6.2 for the individual FEPs b. The uncertainty for reported probability values adequately reflects the influence of parameter uncertainty on the range of model results (i.e., precision) and the model uncertainty, as it affects the timing and magnitude of past events (i.e., accuracy). ANL-WIS-MD-0000019 REV 01 4-26 April 2004 Table 4-7. NUREG-1804 Criteria and the System Level FEPs AMR (Continued) ANL-WIS-MD-0000019 REV 01 4-27 April 2004 NUREG1804Criterion Acceptance Criterion Description How Addressed in this Analysis Report Demonstration of Compliance with Post-closure 1. Evaluation of the Time of an Intrusion Event The technical basis and associated analyses adequately support the selection of time of occurrence of human intrusion, as specified in 10 CFR 63.321 See the technical justification of timing as provided in Attachment III of this analysis report. See Section 6.2.3 for a discussion of human intrusion-related FEPs. The TSPA of human intrusion is performed separately from the Public Health overall TSPA, and meets the requirements for performance and assessments, specified in 10 CFR 63.114. See the technical justification of timing of earliest occurrence of human intrusion without recognition by the driller, provided in Attachment III of this analysis report. See Section 6.2.3 for a discussion of human Environmental Standards Demonstration of Compliance with 2. Evaluation of an Intrusion Event Demonstrates that the Annual Dose to the The TSPA for human intrusion is identical to the TSPA for individual protection, except that it assumes the occurrence of a postulated human intrusion event with characteristics, as defined in 10 CFR 63.322 and excludes the consideration of unlikely natural FEPs. the Human Reasonably Maximally A sufficient number of realizations has been run using the total intrusion-related-FEPs consistent with the Intrusion Exposed Individual in system performance code, to ensure that the results of the requirements of 10 CFR 63.321 and 10 CFR Standard Any Year during the calculations are statistically stable. 63.322. A human intrusion analysis has been provided for a post-10,000 year human intrusion in the FEIS (DOE 2002, Section 5.7.1 [DIRS 155970]). from Section 2.2.1.4.2.3 NUREG-1804 [DIRS 163274]) Compliance Period is Acceptable The estimated repository performance is reasonable and consistent with the analysis of overall repository performance and with the characteristics of the postulated intrusion event. The annual dose curve for limited human intrusion confirms that the repository system meets performance objectives, specified in 10 CFR 63.321, for limited human intrusion events. NOTE: The NUREG-1804 (Section 2.2.1.2.2.3 [DIRS163274]) has two additional criteria regarding the identification of events with probabilities greater than 10-8 per year. Acceptance Criteria 3 applies to probability models, which are not used for System Level FEP evaluations and the criterion is, therefore, not applicable. Acceptance Criteria 4 deals with probability model parameters, and is, therefore, not applicable. DOE = U.S. Department of Energy, FEPs = features, events, and processes, TSPA = total system performance assessment Features, Events, and Processes: System Level 4.3 CODES AND STANDARDS As identified in the review process, but omitted from the TWP, applicable codes and standards include 10 CFR Part 63 ([DIRS 156605]), as discussed in Section 4.2. As applicable for FEP evaluation, portions of the NRC regulations (and the corresponding portions of the EPA regulation at 40 Part 197 [DIRS 155216] that have been incorporated into the NRC regulations) may serve as direct inputs and/or criteria. Regulations used as direct inputs, including the criteria used for FEP screening, are cited in Section 4.1.3, and those providing criteria as identified in the PRD are cited in Section 4.2. ANL-WIS-MD-000019 REV 01 4-28 April 2004 Features, Events, and Processes: System Level 5. ASSUMPTIONS This section addresses assumptions used in the FEP screening for the System Level FEPs. Four general assumptions are used in screening the System Level FEPs. Assumption 5.1: For naturally occurring FEPs, it is assumed that regulations expressed as probability criterion can also be expressed as an annual exceedance probability, which is defined as the probability that a specified value (such as for ground motions or fault displacement) will be exceeded during one year. More specifically, a stated probability screening criterion of one chance in 10,000 in 10,000 years (10-4/104 yr) criterion is assumed equivalent to a 10-8 annual-exceedance probability, and a stated definition of unlikely events as having one chance in 10 in 10,000 years (10-1/104 yr) of occurring is assumed equivalent to a 10-5 annual-exceedance probability. Justification–The definition of annual exceedance probability, and the following justification for this assumption is taken from BSC (2004, Glossary [DIRS 168030]). The assumption of equivalence of annual-exceedance probability is appropriate if the possibility of an event is equal for any given year. This satisfies the definition of a Poisson distribution as “…a mathematical model of the number of outcomes obtained in a suitable interval of time and space, that has its mean equal to its variance…” (Merriam-Webster 1993, p. 899 [DIRS 100468]). This is inferred to mean that naturally occurring, infrequent, and independent events, can be represented as stochastic processes in which distinct events occur in such a way that the number of events occurring in a given period of time depends only on the length of the time period. The use of this assumption is justified in Characterize Framework for Seismicity and Structural Deformation at Yucca Mountain, Nevada (BSC 2004 [DIRS 168030]), which indicates that assuming that the behavior of the earth is generally Poissonian or random is the underlying assumption in all probabilistic hazard analyses. For example, all meteorite impacts are considered as independent events with regard to size, time, and location. Although there may be cases where sufficient data and information exist to depart from this assumption, the Poissonian model is generally an effective representation of nature and represents a compromise between the complexity of natural processes, availability of information, and the sensitivity of results of engineering relevance. Consequently, for geologic processes that occur over long time spans, assuming annual equivalence over a 10,000-year period (a relatively short time span for geologic-related events) is reasonable and consistent with the basis of probabilistic hazard analyses. Therefore, no further confirmation is required. Use–This assumption is used for the FEPs: Changes in the earth’s magnetic field (1.5.03.01.0A) Section 6.2.4.8 Meteorite impact (1.5.01.01.0A) Section 6.2.4.10 Assumption 5.2: The analysis to determine the timing at which a human intrusion could occur without recognition by the drillers is based on physical principles and material properties (see Attachment III). However, inherent in the analysis is the assumption that records and markers are lost, ignored, or otherwise ineffective in preventing or delaying the intrusion. ANL-WIS-MD-000019 REV 01 5-1 April 2004 Features, Events, and Processes: System Level Justification–This assumption is intrinsic in the regulatory requirement to consider that a human intrusion occurs and for determining the earliest time for the intrusion. It is consistent with the regulatory requirement at 10 CFR 63.102(k) ([DIRS 156605]), which states “…it is not possible to make scientifically sound forecasts of the long-term reliability of institutional controls.” It is also conservative and reasonable to assume that surface controls are lost at some time within the 10,000-year regulatory time span. No further confirmation is required. Use–The assumption is used for the FEPs Administrative control of repository site (1.1.10.00.0A) Section 6.2.2.3 Records and markers for repository (1.1.05.00.0A) Section 6.2.2.5 Inadvertent human intrusion (1.4.02.02.0A) Section 6.2.3.2 Drilling Activities (Human Intrusion) (1.4.04.00.0A) Section 6.2.3.7 Mining and Other Underground Activities (1.4.05.00.0A) Section 6.2.3.9 Assumption 5.3: It is assumed that potential naturally occurring events, but perhaps of different magnitude, have occurred at least once in the past within the geologic record used as the basis for the TSPA-LA. Justification–This assumption is justified because it is consistent with the regulations used as direct input. At 10 CFR 63.305(c) ([DIRS 156605]), DOE is directed to “vary factors related to the geology, hydrology, and climate based upon cautious, but reasonable assumptions consistent with present knowledge of factors that could affect the Yucca Mountain disposal system over the next 10,000 years.” See also the discussion on the regulatory concepts for reference biosphere and geologic setting provided in Section 4.1.3. The implication of this assumption is that any discernible impacts or processes related to past events on the site setting are reflected in the present knowledge of natural processes that form the basis of the TSPA. If the subject FEP phenomena are not reflected or discernible in the data used to describe past settings, then they are either of low consequence or of low probability and can be excluded from consideration. Because it is consistent with the regulations, no further confirmation is necessary. Use–This assumption is used throughout. It is particularly germane to FEPs related to processes or phenomena that, speculatively, could affect future states of the system, but for which the magnitude and/or coupling to the effect on the repository is not well defined, or for which consequences in present time are known to be minor. These include FEPs such as: Earth tides (1.5.03.02.0A) Section 6.2.4.8 Changes in the earth’s magnetic field (1.5.03.01.0A) Section 6.2.4.9 Extraterrestrial events (1.5.01.02.0A) Section 6.2.4.10 These types of events are known to occur. However, the effects of the phenomenon or the effects associated with varying magnitudes of the event type and probabilities are not well documented (e.g., effects of a supernova); the form of the coupling process is not well defined (e.g., changes in the earth's magnetic field); or the phenomenon has been shown to have no impact or insignificant impact at the present time (e.g., earth tides). ANL-WIS-MD-000019 REV 01 5-2 April 2004 Features, Events, and Processes: System Level Assumption 5.4: It is assumed for the meteorite impact analysis, that the initial entry velocity of meteors is between 15 and 20 km/sec., that the initial entry angle is vertical, and that fracturing beneath an impact crater is cylindrical with depth. Justification–For the meteorite analysis discussed in Section 6.2.4.5 and provided in Attachment IV, assumptions are made to ensure that the analysis is conservative in nature, and that the range of uncertainty in values is covered. The justification for each segment of the assumption is as follows: Initial Entry Velocities are 15-20 km/sec.–Initial entry velocities are assumed at 15 and 20 km/sec., regardless of the meteor composition or size. These presumed velocities are justified because they are generally conservative and in agreement with available entry velocity data. For fragmented meteors, higher initial velocities tend to result in smaller meteorite-impact crater diameters (Hills and Goda 1993, p. 1140, Figure 17 [DIRS 135281]). The intuitive assumption of increased velocity leading to increased cratering is only correct if the metric is the equivalent radius of the crater produced if all of the impacting material were collected into a single body that hits the ground at a given impacted velocity (see Hills and Goda 1993, p. 1140, Figure 16 [DIRS 135281]). Ram pressures on the meteor are a function of the velocity squared. Once ram pressures exceed material strength properties, the meteor fragments, and the fragments disperse over a wider area (Hills and Goda 1993, Figures 3 and 9 [DIRS 135281]). Additionally, increased initial velocities also result in increased ablation in the atmosphere, resulting in a loss of mass (Hills and Goda 1993, p. 1140, Figure 6 [DIRS 135281]). As a result, for a given meteor below a certain initial radius (which is composition dependent, but generally on the order of 100 m) increased initial velocity leads to decreased impact velocity (Hills and Goda 1993, Figure 10 [DIRS 135281]), and the mass of the largest resulting fragment markedly decreases for initial meteor radius of less than 100 m (Hills and Goda 1993, Figure 11 [DIRS 135281]). Decreased velocity and decreased mass of the largest fragment in turn lead to decreased individual crater radius. Velocities less than 15 km/sec. would result in larger crater diameters. However, lower velocities are not considered because they would not be consistent with available corroborating information. A summary of velocity information from the reviewed literature is provided in Table 5-1. Velocity of known meteoroids and comets range from 12.9 km/sec. for observed meteorites (Chyba 1993, Table 1a [DIRS 135248]) to over 80 km/sec. for long period comets (Marsden and Steel 1994, pp. 233–236 [DIRS 129308]). However, the choice of 15 km/sec. and 20 km/sec., in addition to being conservative with respect to crater formation as just discussed, are also consistent with the average velocities for observed meteors (see Chyba 1993, Table 1a [DIRS 135248] and Ceplecha 1994, Table 2 [DIRS 135243]) with diameters of particular interest (i.e., producing craters with frequencies at or greater than the screening criterion). Also, Hills and Goda (1993, p. 1116 [DIRS 135281]) indicate that V=20 km/s is typical of incoming meteors. Therefore, no further confirmation of this assumption is necessary. ANL-WIS-MD-000019 REV 01 5-3 April 2004 Features, Events, and Processes: System Level Table 5-1. Summary of Velocity Data from Reviewed Literature Velocity (km/s) Source Asteroids Long Period Comets Short Period Comets Not Specified 20.3 Brown et al. 1998 p, 294 [DIRS 162569] 20 60 40 Chapman and Morrison 1994 p. 34 and Figure 1 [DIRS 135245] 14.3 Chyba 1993, p. 701 [DIRS 135248]. Average value excluding object 1991-VG as human artifact 13.3 Chyba 1993, p. 701. median value [DIRS 135248] 20.8 45 38.5 Hughes 1998, p. 35 and 37 [DIRS 162562] 20.7 Ceplecha 1994, Table 2 [DIRS 135243] and Chyba 1993, Table 1a – derived average for 1-10 m [DIRS 135248] 15.8 Ceplecha 1994, Table 2 [DIRS 135243] and Chyba 1993, Table 1a – derived average for 11-60 m [DIRS 135248] 58.2 Marsden and Steel 1994, Table V [DIRS 129308] 25 Grieve 1987 p. 250 [DIRS 135254] 20.1 Shoemaker 1983, p. 468 [DIRS 135308] weighted by probability 20.3 54.4 39.3 18.2 Average 0.36 6.7 0.75 4.1 Standard Deviation 29.4 Average of All Values Regardless of Type 15.9 Standard Deviation Initial Entry Angle is Zero (or Vertical)–Initial entry is at zenith angle zero, or vertical, for all meteoroids. Due to a longer path length, meteoroids entering at nonzero zenith angles have more kinetic energy absorbed in the atmosphere (Hills and Goda 1998 [DIRS 135291]) and would result in smaller crater diameters. Vertical entry (zero entry angle) is an upper-bounding value because all material entering the atmosphere with vertical entry is implicitly considered to have the potential to impact the earth’s surface, and the path length through which atmospheric effects occur is minimized. This assumption is needed because there is no direct input available relating flux and angle of entry. This assumption is conservative and no further confirmation of this assumption is necessary. Zone of Fracturing is Cylindrical with Depth, Rather than Parabolic–For analysis purposes, the vertical extent of effects (e.g., exhumation or fracturing) is represented as a cylinder. The diameter of the cylinder is assumed to correspond to the crater diameter, and the depth corresponds to the depth of interest derived from the crater diameter. In reality, the effects are more likely parabolic in nature (inferred from Wuschke et al. 1995, Figure 1 [DIRS 129326]). If a parabolic zone is used, however, the depth of the effect becomes shallower with distance from the centerline of the crater. Consequently, the volume of material affected by meteorites impacting outside the boundary of the repository (i.e., with the centerline of the crater outside the repository but with crater diameters overlapping the boundary of the repository) would be ANL-WIS-MD-000019 REV 01 5-4 April 2004 Features, Events, and Processes: System Level smaller, and located in shallower geologic units. By assuming a cylindrical zone, the maximum depth of the effect (exhumation or fracturing) is applied throughout the area below the crater diameter and, thereby, conservatively considers a larger volume of the material overlying the repository. Therefore, no further confirmation of this assumption is necessary because the assumption is conservative. Use–This assumption is used in the meteorite impact analysis presented in Attachment IV of this analysis report, which supports the discussion provided in: Meteorite impact (1.5.01.01.0A) Section 6.2.4.5 The assumptions are used in calculating the probability of formation of craters of a given diameter, and to determine the crater diameter occurring at a 10-8 annual exceedance frequency. ANL-WIS-MD-000019 REV 01 5-5 April 2004 Features, Events, and Processes: System Level INTENTIONALLY LEFT BLANK ANL-WIS-MD-000019 REV 01 5-6 April 2004 Features, Events, and Processes: System Level 6. ANALYSES The following sections discuss the System Level FEP analyses. Section 6.1 of this analysis report discusses the methods and approach used for the FEP screening process as applicable to the System Level FEPs, as well as changes in the System Level FEPs from the TSPA-SR to the TSPA-LA FEP list. Section 6.1 also identifies the source of the System Level FEPs, describes the FEP screening process, and provides documentation of consideration of generic issues related to uncertainty, alternative conceptual models, and models and software. Section 6.2 addresses the technical basis for the FEP screening. The FEP analyses presented in Section 6.2 are appropriate because they are consistent with the TSPA approach to satisfy the performance-assessment requirements. These analyses are also appropriate because they address NRC's review criteria described in NUREG-1804 (NRC 2003 [DIRS 163274]) as previously discussed in Section 4.2 of this analysis report. 6.1 METHODS AND APPROACH The methods and approach for FEP screening for TSPA-LA is provided in generic form in The Enhanced Plan for Features, Events, and Processes (FEPs) at Yucca Mountain (BSC 2002 [DIRS 158966]) and the KTI Letter Report, Response to Additional Information Needs on TSPAI 2.05 and TSPAI 2.06 (Freeze 2003 [DIRS 165394]). As described in these documents, the YMP TSPA has chosen to satisfy the performance-assessment requirements by adopting a FEP analysis and scenario development approach. A review of FEP analysis and scenario development in other radioactive waste disposal programs is provided in BSC (2002 Section 2 [DIRS 158966]) and includes a discussion of alternative FEP analysis methods and scenario development approaches. Regardless of the specific approach chosen to perform the screening, the screening process is, in essence, a comparison of each FEP against the criteria specified in Section 6.1.2 of this analysis report. 6.1.1 System Level Feature Events and Processes Origin and Identification The first step of FEP analysis is identification of FEPs potentially relevant to postclosure performance of the Yucca Mountain repository. Consistent with that approach, FEP screening for postclosure probability of the System Level FEPs uses the following definitions, as taken from BSC (2001, Appendix A [DIRS 154365]): feature – An object, structure, or condition that has a potential to affect disposal system performance. event – A natural or anthropogenic phenomenon that has a potential to affect disposal system performance and that occurs during an interval that is short compared to the period of performance. process – A natural or anthropogenic phenomenon that has a potential to affect disposal system performance and that operates during all or a significant part of the period of performance. ANL-WIS-MD-000019 REV 01 6-1 April 2004 Features, Events, and Processes: System Level The development of a comprehensive list of FEPs that are potentially relevant to performance of the Yucca Mountain repository is an ongoing, iterative process based on site-specific information, design, and regulations. The approach for developing an initial list of FEPs in support of TSPA-SR was documented in BSC (2001 [DIRS 154365]). The initial FEP list contained 328 FEPs, of which 176 were included in TSPA-SR models (BSC 2001, Tables B-9 through B-17 [DIRS 154365]). Each FEP was assigned a unique YMP FEP database number, based on the Nuclear Energy Agency categories. The database number is the primary method for identifying FEPs, and consists of an eight-digit number having a format x.x.xx.xx.xx. The numbering system used by the Nuclear Energy Agency is further explained in BSC (2001 [DIRS 154365]). A similar numbering system is used for the TSPA-LA FEP list to provide a unique identifier for each FEP. In general, TSPA-SR FEPs with numbers ending in .00 were converted to TSPA-LA FEPs with numbers ending in .0A. Where splitting existing TSPA-SR FEPs created new FEPs for TSPA-LA, the new FEPs end in .0B, .0C, etc., to ensure traceability to their origin in TSPA-SR. The results of the System Level FEP activities described in the TWP (BSC 2004, Section 1.2.2 [DIRS168024]) are documented in this analysis report as shown in Section 6.2. The revision of the FEP organization and descriptions were needed to implement The Enhanced Plan for Features Events and Processes (FEPs) at Yucca Mountain (BSC 2002, Section 3.2 [DIRS 158966]) and the KTI Letter Report, Response to Additional Information Needs on TSPAI 2.05 and TSPAI 2.06 (Freeze 2003 [DIRS 165394]). The particular revision efforts included: • Review of the FEP hierarchical system • Recategorization and redefinition of System Level FEPs as needed to provide a consistent and appropriate level of detail • Review of updated analysis reports and modeling reports as needed, and integration with subject matter experts (SMEs). As part of the TSPA-LA FEP evaluation, the FEP 3.2.10.00.0A (Atmospheric transport of contaminants) was removed from the System Level FEP list and reassigned, and the FEP 2.1.01.04.0A (Repository scale heterogeneity of waste) was assigned to the System Level FEP list. Consequently, this analysis report addresses the 31 FEPs that are identified as System Level FEPs for TSPA-LA as noted and derived from the preliminary YMP FEP Database (DTN: MO0312SEPFEPS5.000 [DIRS 167431]). Two additional FEPs were added. These address the effect of preceding disruptive events on determining the timing of human intrusion (1.4.02.03.0A Igneous Event Precedes Human Intrusion; and 1.4.02.03.0B Seismic Event Precedes Human Intrusion). Changes to the preliminary FEP list, including additions and deletions during the review process, are given in Table 6-1. That table summarizes the changes from TSPA–SR to the FEP organization and descriptions being used for TSPA-LA that appear in this analysis report, and provides a comparison of the resulting screening decisions and bases as provided in Section 6.2 of this analysis report. Additional changes made in the descriptions from the cited Data Tracking Number (DTN) are also presented in Table 6-1 under the TSPA-LA description heading. The changes are shown as italics. ANL-WIS-MD-000019 REV 01 6-2 April 2004 Table 6-1. Changes to the System Level FEPs from TSPA-SR to TSPA-LA TSPA-LA FEP and Description TSPA-SR FEP and Description TSPA–SR Screening Decision (italics denote changes from DTN: MO0312SEPFEPS5.000 [DIRS 167431]) Remarks on Description Changes Section ASSESSMENT BASIS AND MODELING REQUIREMENTS FEPS 0.1.02.00.00 Timescales of Concern Included 0.1.02.00.0A Timescales of Concern Minor changes were made 6.2.1.1 This FEP describes the timescale of concern This FEP addresses the timescale of to clarify the description. over which the disposal system presents a concern over which the disposal system significant health or environmental hazard. presents a significant health or environmental hazard. 0.1.03.00.00 Spatial Domain of Concern Included 0.1.03.00.0A Spatial Domain of Concern Minor changes were made 6.2.1.2 This FEP describes the spatial domain of This FEP addresses the spatial domain of to clarify the description. concern over which the disposal system may concern over which the disposal system present a significant health or environmental may present a significant health or hazard. environmental hazard. 0.1.09.00.00 Regulatory Requirements and Included 0.1.09.00.0A Regulatory Requirements Minor changes were made 6.2.1.3 Exclusions and Exclusions to clarify the description. This FEP describes regulatory requirements This FEP addresses regulatory and guidance specific to the Yucca Mountain requirements and guidance specific to the repository. Yucca Mountain repository. 0.1.10.00.00 Model and Data Issues Included 0.1.10.00.0A Model and Data Issues Minor changes were made 6.2.1.4 This FEP describes issues identified by other programs related to modeling of the disposal system. Model and data issues are general (i.e., methodological) issues affecting the assessment modeling process and use of data. These issues include the Excluded for un- modeled design features This FEP addresses issues related to modeling of the disposal system. Model and data issues are general (i.e., methodological) issues affecting the assessment modeling process and use of data. These issues include the approach to clarify the description. Reassigned the issue of “features not modeled” to a more appropriate FEP dealing with inadequate quality control. approach and assumptions associated with and assumptions associated with the the selection of conceptual models, the selection of conceptual models, the mathematical implementation of conceptual mathematical implementation of models, model geometry and dimensionality, conceptual models, model geometry and models of coupled processes, and boundary dimensionality, models of coupled and initial conditions. These issues also processes, and boundary and initial include the derivation of data values and conditions. These issues also include the correlations. derivation of data values and correlations. ANL-WIS-MD-000019 REV 01 6-3 April 2004 Table 6-1. Changes to the System Level FEPs from TSPA-SR to TSPA-LA (Continued) TSPA-SR FEP and Description TSPA–SR Screening Decision TSPA-LA FEP and Description (italics denote changes from DTN: MO0312SEPFEPS5.000 [DIRS 167431]) Remarks on Description Changes Section ASSESSMENT BASIS AND MODELING REQUIREMENTS FEPS (Continued) 1.1.07.00.00 Repository Design This category contains FEPs related to the design of the repository, and the ways in which the design contributes to long-term performance. Changes to or deviations from the specified design may affect the long-term performance of the disposal system. Included for licensed repository design and for design modifications Excluded for significant undetected deviations from design Excluded for inadequacy or lack of safety of the proposed design and for non-YMP design elements 1.1.07.00.0A Repository Design This FEP addresses the consideration of the design of the repository and the ways in which the design contributes to long- term performance. The performance assessment must account for design features, material characteristics, and the ways in which the design influences the evolution of the in-drift environment. Modified the description to move the issue of “undetected deviations, inadequacy, and lack of safety” into a more appropriate FEP dealing with inadequate quality control and deviation from design. This was done to resolve the mixed include/exclude screening decision. 6.2.1.5 1.1.13.00.00 Retrievability Included design 1.1.13.00.0A Retrievability Minor changes were made to 6.2.1.6 This category contains FEPs related to design, emplacement, operational, or administrative measures that might be applied or considered in order to enable or ease retrieval of wastes. There may be a requirement to retrieve all or part of the waste stored in the repository, for example, to recover valuable fissile materials or to elements and emplacement Excluded for operational and administrative considerations This FEP addresses design, emplacement, operational, or administrative measures that might be applied or considered in order to enable or ease retrieval of wastes. There may be a requirement to retrieve all or part of the waste stored in the repository, for example, to recover valuable fissile the description. Modified the disposition discussion to identify the operational and the administrative issues as preclosure concerns. This was done to resolve the mixed include/exclude screening decision. replace defective containers. materials or to replace defective containers. Not Applicable Not Applicable 2.1.01.04.0A Repository Scale Spatial Heterogeneity of Emplaced Waste Waste placed in Yucca Mountain will have physical, chemical, and radiological properties that vary spatially, resulting in variation in the mass of radionuclides New FEP for System Level. Reassigned for TSPA-LA due to overarching nature of the FEP. 6.2.1.7 available for transport from different parts of the repository. ANL-WIS-MD-000019 REV 01 6-4 April 2004 Table 6-1. Changes to the System Level FEPs from TSPA-SR to TSPA-LA (Continued) TSPA-SR FEP and Description TSPA–SR Screening Decision TSPA-LA FEP and Description (italics denote changes from DTN: MO0312SEPFEPS5.000 [DIRS 167431]) Remarks on Description Changes Section PROCESS AND SITE CONTROL FEPs 1.1.05.00.00 Records and Markers, Repository Included for construction of markers 1.1.05.00.0A Records and Markers for the Repository Minor changes were made to the description. Modified the 6.2.2.1 This category contains FEPs related to the retention of records of the contents of the repository and markers constructed to inform future humans of the location and contents of the repository. Performance assessments must consider the potential effects of human activities that might take place within the controlled area at a future time when to inform future humans of the location and contents of the repository, retention of records, and for lack of knowledge of the repository at future times This FEP addresses both the retention of records of the contents of the repository and the markers constructed to inform future humans of the location and contents of the repository. Performance assessments must consider the potential effects of human activities that might take place within the controlled area at a future screening argument to exclude to eliminate the need for a mixed include/exclude screening decision. institutional controls and/or knowledge of the Excluded for efficacy of time when institutional controls and/or presence of a repository cannot be markers and record knowledge of the presence of a repository assumed. retention to prevent cannot be assumed. intrusion during the postclosure period 1.1.08.00.00 Quality Control Included for quality 1.1.08.00.0A Inadequate Quality Control Changed name to better 6.2.2.2 This category contains FEPs related to quality assurance and control procedures, and tests during the design, construction, and operation of the repository, as well as the manufacture of the waste forms, containers, and engineered features. Lack of quality control could result in material defects, faulty waste package fabrication, and faulty or non-design-standard construction, all of which may lead to control Excluded for material defects, faulty fabrication, and faulty or non-design-standard construction Excluded for installation of panels, silos, and drains and Deviations from Design This FEP addresses issues related to inadequate quality assurance and control procedures and inadequate testing during the design, construction, and operation of the repository. It also includes inadequacy in the manufacture of the waste forms, containers, and engineered features. Lack of quality control could result in a poorly designed repository, reflect focus of the FEP. Expanded the description to focus on deficiencies and lack of safety. Incorporated language from the Repository Design FEP to resolve the mixed include/exclude screening decision. reduced effectiveness of the engineered unmodeled design features, deviations barriers. from design, material defects, faulty waste package fabrication, and faulty or non- design standard construction. All of these may lead to reduction in the effectiveness of the engineered barriers. ANL-WIS-MD-000019 REV 01 6-5 April 2004 Table 6-1. Changes to the System Level FEPs from TSPA-SR to TSPA-LA (Continued) TSPA-SR FEP and Description TSPA–SR Screening Decision TSPA-LA FEP and Description (italics denote changes from DTN: MO0312SEPFEPS5.000 [DIRS 167431]) Remarks on Description Changes Section PROCESS AND SITE CONTROL FEPs (Continued) 1.1.09.00.00 Schedule and Planning Excluded 1.1.09.00.0A Schedule and Planning Minor changes were made to 6.2.2.3 This category contains FEPs related to the This FEP addresses the sequences of the description. sequences of events and activities occurring events and activities occurring during during construction, operation, and closure construction, operation, and closure of the of the repository. Deviations from the design repository. Deviations from the design, construction or waste emplacement construction, or waste emplacement schedule may affect the long-term schedule may affect the long-term performance of the disposal system. performance of the disposal system. 1.1.10.00.00 Administrative Control, Repository Site This category contains FEPs related to administrative control of the repository site. Administrative control can reduce the possibility that human activities might take place within the controlled area. Included for administrative control during the preclosure period, for initial construction of markers and archiving of records, and for subsequent loss of administrative control 1.1.10.00.0A Administrative Control of the Repository Site This FEP addresses administrative control of the repository site. Administrative control can reduce the potential for detrimental or unplanned human activity within the controlled area that could inadvertently cause or accelerate the release of radioactive material. Minor changes were made to the description. Modified the screening argument to eliminate the need for a mixed include/exclude screening decision. 6.2.2.4 Excluded for efficacy of administrative controls – during the postclosure period 1.1.11.00.00 Monitoring of Repository Excluded for monitoring 1.1.11.00.0A Monitoring of the Repository Changed the description to 6.2.2.5 This category contains FEPs related to monitoring that is carried out during or after operations, for either operational safety or verification of long-term performance. Monitoring boreholes could provide enhanced pathways between the surface operations Included for monitoring wells and boreholes within the stylized human-intrusion scenario This FEP addresses the potential for monitoring that is carried out during or after operations, for either operational safety or verification of long-term performance, to detrimentally affect long- term performance. For instance, focus on detrimental effects and changed the screening decision and screening argument to eliminate the mixed include/exclude screening decision. and the repository. monitoring boreholes could provide enhanced pathways between the surface and the repository. ANL-WIS-MD-000019 REV 01 6-6 April 2004 Table 6-1. Changes to the System Level FEPs from TSPA-SR to TSPA-LA (Continued) TSPA-SR FEP and Description TSPA–SR Screening Decision TSPA-LA FEP and Description (italics denote changes from DTN: MO0312SEPFEPS5.000 [DIRS 167431]) Remarks on Description Changes Section PROCESS AND SITE CONTROL FEPs (Continued) 1.1.12.01.00 Accidents and Unplanned Excluded 1.1.12.01.0A Accidents and Unplanned No changes were made to 6.2.2.6 Events During Operation Events During Construction and Operation the description. The long-term performance of the disposal The long-term performance of the system might be seriously affected by disposal system might be seriously unplanned or improper activities that take affected by unplanned or improper place during construction, operation, and activities that take place during closure of the repository. construction, operation, and closure of the repository. HUMAN INTRUSION FEPs 1.4.02.01.00 Deliberate Human Intrusion Included for a human-1.4.02.01.0A Deliberate Human Intrusion No changes were made to 6.2.3.1 Humans could deliberately intrude into the repository. Without appropriate precautions, intruders could experience high radiation exposures. Moreover, containment may be left damaged, which could increase radionuclide release rates to the biosphere. Motivation for deliberate human intrusion includes mining, waste retrieval, site intrusion stylized analysis Excluded for deliberate intrusion Humans could deliberately intrude into the repository. Without appropriate precautions, intruders could experience high radiation exposures. Moreover, containment may be left damaged, which could increase radionuclide release rates to the biosphere. Motivation for deliberate human intrusion includes mining, waste description or screening decision. Eliminated the discussion of stylized human intrusion within the screening argument and thereby resolved the mixed include/exclude screening decision. remediation/improvement, archaeology, retrieval, site remediation/improvement, sabotage, and acts of war. archaeology, sabotage, and acts of war. 1.4.02.02.00 Inadvertent Human Intrusion Included 1.4.02.02.0A Inadvertent Human No changes were made to 6.2.3.2 Humans could accidentally intrude into the repository. Without appropriate precautions, intruders could experience high radiation exposures. Moreover, containment may be left damaged, which could increase Intrusion Humans could accidentally intrude into the repository. Without appropriate precautions, intruders could experience high radiation exposures. Moreover, the description. Screening decision and screening argument were changed to exclude from TSPA-LA based on timing of intrusion. radionuclide release rates to the biosphere. containment may be left damaged, which Inadvertent human intrusion might occur could increase radionuclide release rates during scientific, mineral, or geothermal to the biosphere. Inadvertent human exploration. intrusion might occur during scientific, mineral, or geothermal exploration. ANL-WIS-MD-000019 REV 01 6-7 April 2004 Table 6-1. Changes to the System Level FEPs from TSPA-SR to TSPA-LA (Continued) TSPA-SR FEP and Description TSPA–SR Screening Decision TSPA-LA FEP and Description (italics denote changes from DTN: MO0312SEPFEPS5.000 [DIRS 167431]) Remarks on Description Changes Section HUMAN INTRUSION FEPs (Continued) Not Applicable Not Applicable 1.4.02.03.0A Igneous Event Precedes Human Intrusion An igneous event, such as a dike, intersects the repository and damages one or more waste packages. The damage is such that the material and structural New FEP needed to address disruptive event and human intrusion interaction 6.2.3.3 properties of the drip shield and/or waste package are significantly altered. Because of the change in properties, an intruder, using groundwater exploration drilling techniques, may not be able to recognize that something other than naturally- occurring materials have been encountered. Not Applicable Not Applicable 1.4.02.03.0B Seismic Event Precedes New FEP needed to address 6.2.3.4 Human Intrusion A seismic event occurs at the repository and damages one or more waste disruptive event and human intrusion interaction packages. The damage is such that the material and structural properties of the drip shield and/or waste package are significantly altered. Because of the change in properties an intruder, using groundwater exploration drilling techniques, may not be able to recognize that something other than naturally-occurring materials have been encountered. 1.4.03.00.00 Unintrusive Site Investigation Excluded 1.4.03.00.0A Unintrusive Site Investigation Minor changes were made to 6.2.3.5 This category contains FEPs related to This FEP addresses airborne, geophysical, the description. airborne, geophysical, or other surface-or other surface-based investigations of a based investigations of a repository site repository site after its closure. after its closure. ANL-WIS-MD-000019 REV 01 6-8 April 2004 Table 6-1. Changes to the System Level FEPs from TSPA-SR to TSPA-LA (Continued) TSPA-SR FEP and Description TSPA–SR Screening Decision TSPA-LA FEP and Description (italics denote changes from DTN: MO0312SEPFEPS5.000 [DIRS 167431]) Remarks on Description Changes Section HUMAN INTRUSION FEPs (Continued) 1.4.04.00.00 Drilling Activities (Human Included for a human 1.4.04.00.0A Drilling Activities (Human Minor changes were made to 6.2.3.6 Intrusion) intrusion stylized Intrusion) the description. The This category contains FEPs related to any type of drilling activity in the repository environment. These may be taken with or without knowledge of the repository. Drilling activities may be associated with natural resource exploration (water, oil and gas, minerals, geothermal energy), waste disposal (liquid), fluid storage (hydrocarbon, gas), or reopening existing boreholes. analysis Excluded for specific types of drilling analyses This FEP addresses any type of drilling activity in the repository environment. These activities may be with or without awareness of the presence of the repository and with or without consent of the repository licensee. Drilling activities may be associated with natural resource exploration (water, oil and gas, minerals, geothermal energy), waste disposal (liquid), fluid storage (hydrocarbon, gas), or screening argument changed to focus on economic motivation for conducting drilling operations (exploration, water resources, or other). Changed the discussion of the human intrusion stylized analysis to address the mixed include/exclude decision. reopening existing boreholes. 1.4.04.01.00 Effects of Drilling Intrusion Included for interactions 1.4.04.01.0A Effects of Drilling Intrusion No changes were made to 6.2.3.7 Drilling activities that intrude into the repository may create new release pathways to the biosphere and alter existing pathways. Possible effects of a drilling intrusion include interaction with waste containers, increased saturation in and changes in conditions Excluded for materials brought to the surface Drilling activities that intrude into the repository may create new release pathways to the biosphere and alter existing pathways. Possible effects of a drilling intrusion include interaction with waste packages, increased saturation in the description, but the screening decision was changed. The screening argument was changed to exclude based on timing of intrusion. the repository leading to enhanced the repository leading to enhanced transport to the SZ, changes to transport to the SZ, changes to groundwater and EBS chemistry, and groundwater and EBS chemistry, and waste brought to surface. waste brought to surface. 1.4.05.00.00 Mining and Other Excluded 1.4.05.00.0A Mining and Other No changes were made to 6.2.3.8 Underground Activities (Human Intrusion) Underground Activities (Human Intrusion) the description or screening Mining and other underground human Mining and other underground human decision. activities (e.g., tunneling, underground activities (e.g., tunneling, underground construction, quarrying) could disrupt the construction, quarrying) could disrupt the disposal system. disposal system. ANL-WIS-MD-000019 REV 01 6-9 April 2004 Table 6-1. Changes to the System Level FEPs from TSPA-SR to TSPA-LA (Continued) TSPA-SR FEP and Description TSPA–SR Screening Decision TSPA-LA FEP and Description (italics denote changes from DTN: MO0312SEPFEPS5.000 [DIRS 167431]) Remarks on Description Changes Section HUMAN INTRUSION FEPs (Continued) 1.4.11.00.00 Explosions and Crashes Excluded 1.4.11.00.0A Explosions and Crashes No changes were made to 6.2.3.9 (Human Activities) (Human Activities) the description or screening Explosions or crashes resulting from future Explosions or crashes resulting from future decision. human activities may affect the long-term human activities may affect the long-term performance of the repository. Explosions performance of the repository. Explosions may result from nuclear war, underground may result from nuclear war, underground nuclear testing, or resource exploitation. nuclear testing, or resource exploitation. 3.3.06.01.00 Repository Excavation (also Excluded 3.3.06.01.0A Repository Excavation No changes were made to 6.2.3.10 listed as Toxicity of Mined Rock) Excavation of the repository and/or its contents may result in the production of Excavation of the repository and/or its contents may result in the production of tailings, which may subsequently release the description or screening decision. Changed the title to “Repository Excavation”. tailings, which may subsequently release toxic contaminants. toxic contaminants. MISCELLANEOUS GEOLOGIC AND ASTRONOMIC FEPS 1.2.05.00.00 Metamorphism Excluded 1.2.05.00.0A Metamorphism Minor changes were made to 6.2.4.1 This category includes FEPs related to This FEP addresses regional the description. regional metamorphism, which has the metamorphism, which has the potential to potential to affect the long-term affect the long-term performance of the performance of the repository if it occurs. repository if it occurs. Metamorphic activity Metamorphic activity is defined as solid is defined as solid state recrystallization state recrystallization changes to rock changes to rock properties and geologic properties and geologic structures through structures through the effects of heat the effects of heat and/or pressure. and/or pressure. ANL-WIS-MD-000019 REV 01 6-10 April 2004 Table 6-1. Changes to the System Level FEPs from TSPA-SR to TSPA-LA (Continued) MISCELLANEOUS GEOLOGIC AND ASTRONOMIC FEPS (Continued) 1.2.08.00.00 Diagenesis Excluded 1.2.08.00.0A Diagenesis Minor changes were made to 6.2.4.2 This category contains FEPs related to This FEP addresses natural processes that the description. natural processes that alter the mineralogy alter the mineralogy or other properties of or other properties of rocks after the rocks rocks after the rocks have formed under have formed under temperature- and temperature- and pressure-conditions pressure-conditions normal to the upper normal to the upper few kilometers of the few kilometers of the earth's crust. earth's crust. Diagenesis includes Diagenesis includes chemical, physical, chemical, physical, and biological and biological processes that take place in processes that take place in rocks after rocks after formation but before eventual formation but before eventual metamorphism or weathering. This FEP is metamorphism or weathering. This FEP is assumed to refer to natural diagenetic assumed to refer to natural diagenetic processes only. processes only. 1.2.09.00.00 Salt Diapirism and Dissolution Excluded 1.2.09.00.0A Salt Diapirism and Minor changes were made to 6.2.4.3 This category contains FEPs related to Dissolution the description. geologic processes primarily relevant to This FEP addresses geologic processes repositories located in salt and evaporite relevant to repositories located in salt deposits. Diapirism refers to the tendency deposits. Salt diapirism refers to the of any rock, but most particularly salt, to tendency of salt to flow under lithostatic flow under lithostatic loading when density loading when density and viscosity and viscosity contrasts with surrounding contrasts with surrounding strata are strata are favorable. Salt domes are the favorable. Salt domes are the best-known best-known example of salt diapirism. example of salt diapirism. Salt dissolution Dissolution can occur when any soluble can occur when any soluble mineral is mineral is removed by flowing water, and removed by flowing water, and large-scale large-scale dissolution is a potentially dissolution is a potentially important important process in rocks that are process in rocks that are composed composed predominantly of water-soluble predominantly of water-soluble evaporite evaporite minerals, such as salt. minerals, such as salt. 1.2.09.01.00 Diapirism Excluded 1.2.09.01.0A Diapirism No changes were made to 6.2.4.4 The process by which plastic, low density rocks (most commonly evaporites) may The process by which plastic, low density rocks (most commonly evaporites) may the description or screening decision. flow under lithostatic loading when density flow under lithostatic loading when density and viscosity contrasts with surrounding and viscosity contrasts with surrounding strata are favorable. Such a process would strata are favorable. Such a process would modify the groundwater flow regime and modify the groundwater flow regime and affect radionuclide transport. affect radionuclide transport. ANL-WIS-MD-000019 REV 01 6-11 April 2004 Table 6-1. Changes to the System Level FEPs from TSPA-SR to TSPA-LA (Continued) MISCELLANEOUS GEOLOGIC AND ASTRONOMIC FEPS (Continued) 1.5.01.01.00 Meteorite Impact Excluded 1.5.01.01.0A Meteorite Impact No changes were made to 6.2.4.5 Meteorite impact close to the repository site might disturb or remove rock so that Meteorite impact close to the repository site might disturb or remove rock so that the description or screening decision. radionuclide transport to the surface is radionuclide transport to the surface is accelerated. Possible effects include accelerated. Possible effects include alteration of flow patterns (faults, fractures), alteration of flow patterns (faults, fractures), changes in rock stress, cratering, and changes in rock stress, cratering, and exhumation of waste. exhumation of waste. 1.5.01.02.00 Extraterrestrial Events Excluded 1.5.01.02.0A Extraterrestrial Events Only minor changes were 6.2.4.6 Extraterrestrial events (e.g., supernova, Extraterrestrial events (e.g., supernovae, made to the description solar flare, gamma-ray burster, alien life solar flares, gamma-ray bursters, alien life forms) may affect long-term performance of forms) may affect long-term performance of the disposal system. the disposal system. 1.5.03.01.00 Changes in the Earth's Excluded 1.5.03.01.0A Changes in the Earth’s No changes were made to 6.2.4.7 Magnetic Field Magnetic Field the description or screening Changes in the earth's magnetic field could Changes in the earth's magnetic field could decision. affect the long-term performance of the affect the long-term performance of the repository. repository. 1.5.03.02.00 Earth Tides Excluded 1.5.03.02.0A Earth Tides No changes were made to 6.2.4.8 Small changes of the gravitational field due to celestial movements (sun and moon) Small changes of the gravitational field due to celestial movements (sun and moon) the description or screening decision. cause earth tides and may, in turn cause cause earth tides and may, in turn, cause pressure variations in the groundwater flow pressure variations in the groundwater flow systems. systems. 2.2.06.05.0A Salt Creep Excluded 2.2.06.05.0A Salt Creep No changes were made to 6.2.4.9 Salt creep will lead to changes in the stress field, compaction of the waste and Salt creep will lead to changes in the stress field, compaction of the waste packages, the description or screening decision containers, and consolidation of the long-and consolidation of the long-term term components of the sealing system. components of the sealing system. 2.3.13.03.00 Effects of Repository Heat on Excluded 2.3.13.03.0A Effects of Repository Heat on No changes were made to 6.2.4.10 the Biosphere the Biosphere the description or screening The heat released from radioactive decay of This FEP addresses the heat released from decision the waste will increase the temperatures at radioactive decay of the waste that will the surface above the repository. This could increase the temperatures at the surface result in local or extensive changes in the above the repository. This could result in ecological characteristics. local or extensive changes in ecological characteristics. ANL-WIS-MD-000019 REV 01 6-12 April 2004 ANL-WIS-MD-000019 REV 01 6-13 April 2004 Table 6-1. Changes to the System Level FEPs from TSPA-SR to TSPA-LA (Continued) TSPA-SR FEP and Description TSPA–SR Screening Decision TSPA-LA FEP and Description (italics denote changes from DTN: MO0312SEPFEPS5.000 [DIRS 167431]) Remarks on Description Changes Section MISCELLANEOUS GEOLOGIC AND ASTRONOMIC FEPS (Concluded) 3.2.10.00.00 Atmospheric Transport of Contaminants This category contains FEPs related to transport of contaminants in the atmosphere. Atmospheric transport includes radiotoxic and chemotoxic species in the air as gas, vapor, particulates, or aerosol. Transport processes include wind, plowing and irrigation, degassing, saltation, and precipitation. Included for transport mechanisms and species (via ashfall). Excluded for volatile radionuclides as a gaseous release through the host rock 3.2.10.00.0A Atmospheric Transport of Contaminants Atmospheric transport includes radiotoxic and chemotoxic species in the air as gas, vapor, particulates, or aerosol. Transport processes include wind, plowing and irrigation, degassing, saltation, and precipitation. Minor changes were made to the description. Eliminated discussion of ash fall within this FEP to resolve the mixed include/exclude decision. Not assigned to System Level FEPs for TSPA-LA FEPs = features, events, and processes, TSPA-LA = total system performance for license application, TSPA-SR = total system performance assessment for site description 6.1.2 Feature, Event, and Process Screening Process As described in Section 6.1.1, the first step in the FEP analysis was the identification of FEPs. The second step includes the screening of each FEP against the FEP screening criteria. Each FEP is screened against the regulations, assumptions, guidance, or specific criteria that are summarized in the form of three FEP screening statements: 1) The event has at least one chance in 10,000 of occurring over 10,000 years (see 10 CFR 63.114(d) ([DIRS 156605])) 2) The magnitude and time of the resulting radiological exposure to the RMEI, or radionuclide release to the accessible environment, would be significantly changed by its omission (see 10 CFR 63.114 (e and f) ([DIRS 156605])). Additionally, the Acceptance Criteria 2 in NUREG-1804 (NRC 2003, Section 2.2.1.2.1.3 [DIRS 163274]) calls for evaluating the FEPs based on the regulations. This criterion can be summarized in the form of a third FEP screening statement: 3) The FEP is not excluded by regulation. If there are affirmative conditions for all three screening criteria, the FEP is “Included” in the TSPA-LA model. By default, FEPs are included in the TSPA, unless they are shown to be of low probability, of low consequence, or excluded by regulation. Any negating condition in the three screening criteria “Excludes” the FEP from the TSPA-LA model. The first screening criterion (probability) is addressed in Section 6.1.2.1; the second criterion (consequence) is addressed in Section 6.1.2.[should there be a 2 added to the section number?]; the third criterion (regulatory) is addressed in Section 6.1.2.3. 6.1.2.1 Exclusion by Low Probability For the TSPA, an event is defined as "a natural or anthropogenic phenomenon that has a potential to affect disposal system performance and that occurs during an interval that is short compared to the period of performance" (BSC 2001, Appendix A [DIRS 154365]). For postclosure, the event probability criterion is set at one chance in 10,000 of the event occurring in 10,000 years (10 CFR 63.114(d) [DIRS 156605])). Event probability screening is the consideration of the probability of a phenomenon occurring independent of its effect on the repository. This is particularly germane to processes where the phenomena are well defined. If it can be demonstrated that a phenomenon, independent of its effect on the repository, is of low probability, then the phenomenon is excluded from the TSPA. 6.1.2.2 Exclusion by Low Consequence This screening criterion allows FEPs to be excluded from further consideration if the magnitude and time of the resulting radiological exposures to the RMEI, or radionuclide releases to the accessible environment would not be “significantly changed” by the omission of the FEP from the TSPA-LA model. The terms “significantly changed” and “changed significantly” are ANL-WIS-MD-000019 REV 01 6-14 April 2004 undefined in the NRC and EPA regulations. The absence of significant change (i.e., an insignificant change if the FEP is omitted) is inferred for FEP-screening purposes to be equivalent to having no effect or negligible effect. The low-consequence arguments can be made for the FEP screening by demonstrating that a particular FEP has no effect on the distribution of an intermediate-performance measure that can be linked to radiological exposure or radionuclide release, or it may be given directly in terms of the effect on radiological exposure or radionuclide release. If a FEP can be shown to have negligible impact on unsaturated zone or saturated zone flow and transport, waste-package integrity, and/or other components of the EBS or natural barrier system, then the FEP does not provide a mechanism that results in an increase in the radiological exposure or radionuclide release. Various means to demonstrate negligible impact include site-specific data, sensitivity analyses, expertise of SMEs (including, in some cases, the expert elicitation process), natural analogues, modeling studies outside of the TSPA, and reasoned arguments based on literature research or corroborative data. In some cases, the demonstration may be direct, using results of computer simulations of the potential event or process. For example, by demonstrating that including a particular waste form has no effect on the concentrations of radionuclides transported from the repository in the aqueous phase, it is also demonstrated that including this waste form in the inventory would not affect other performance measures, such as radiological exposure of the RMEI, that are dependent on concentration. Explicit modeling of the characteristics of this waste form, therefore, could be excluded from further consideration in the TSPA, where concentration of radionuclides has a primary impact on dose or the release of radionuclides. A low-consequence argument can include the probability of the FEPs because the consequence (dose or concentration) include probability weighting of events or processes. One can define a threshold value at which an event or process has the potential to affect repository performance, and then evaluates the probability of the threshold being violated. This approach is justified because: (1) FEPs can be defined temporally, spatially, and in amplitude; (2) the phenomena and effect of the interaction can be quantified (or at least bounded) and, therefore, incorporated into the design in such a way that the potential effect of the FEP is eliminated or minimized; (3) the implementation of the design and changes to the design are subject to a performance- confirmation process; and 4) the "as-built" design can be verified (see Section 6.1.7). This use of probability to support a low-consequence argument is particularly germane to FEPs involving potential breaching of containers due to a geologic phenomenon. An example of this approach is FEP 1.5.01.01.0A (Meteorite impact). Based on the diameter of an impact crater, a probability of such an event can be quantified, and the associated depth of fracturing can be determined. The minimum crater diameter sufficient to affect repository performance is directly related to the depth of the repository below the ground surface or the depth of some defined key geohydrologic stratum. Craters that are of insufficient size to fracture to the threshold depth can be therefore excluded based on consequence independent of cratering probability. Larger crater diameters extending can be excluded if their probability-weighted consequence is insignificant. Extremely large craters can be excluded based on their low probability because they have less than one chance in 10,000 of occurring in 10,000 years. ANL-WIS-MD-000019 REV 01 6-15 April 2004 Another method of supporting a low-consequence argument is to quantify the conditional exposure or conditional radionuclide release (i.e., that exposure or release which results presuming that the FEP occurs), and demonstrate that, once weighted by the probability of the associated scenario class occurring, the exposure or release is of no significance. 6.1.2.3 Exclusion by Regulation The NRC Acceptance Criteria 2 for FEP screening published in NUREG-1804 (NRC 2003, Section 2.2.1.2.1.3 [DIRS 163274]) allows for exclusion of a FEP if the process is specifically excluded by the regulations as described in Acceptance Criterion 2 Screening of the Initial List of Features, Events, and Processes Is Appropriate. 6.1.3 Direct Input, References and Corroborative Information, Literature Searches, and other Background Information Per the requirements of AP-SIII.9Q (particularly, Attachment 2, Section 6), the direct inputs used in this AMR are identified in Section 4 and are discussed based on the classification of the type of direct input. Technical products used as direct inputs in this analysis report have been obtained from controlled source documents and are cited using the appropriate document identifiers or records system accession numbers. Sources include, but are not limited to, YMP AMRs, YMP Technical Reports, and other YMP documents, databases, and drawings. The NRC regulations also provide direct inputs for the FEP evaluations. These direct inputs are identified, and discussed in Section 4 of this AMR. However, the nature of the System Level FEPs is diverse and encompasses a wide range of naturally occurring phenomena that are not necessarily specific to YMP. Consequently, other sources of direct inputs are used, and corroborative information is cited to support the direct input. Such information was obtained from literature searches of peer-reviewed journals, other widely recognized scientific periodicals, compendiums of technical articles, and other appropriate sources such as technical handbooks and textbooks. Direct Inputs from these non-YMP originating sources are identified in Section 4.1.3.2. Qualification of such direct inputs, per AP-SIII.9Q, is discussed in Attachment II of this analysis report. AP-SIII.9Q, Attachment 2 allows for the use of attachments to the main body of the scientific analysis report. To wit “Supporting documentation, such as computer output, that are lengthy or cannot be conveniently included with the main text of the documentation may be included as attachments.” Accordingly, lists and/or tables of the direct inputs and the corroborating/ supporting data are provided in Attachment II, along with a description of the result of literature searches and discussions that substantiate and corroborate the input used in the various FEP discussions. Attachments, divided based on subject matter, are used to provide the procedurally required information in an effort to avoid redundancy in the main body of this analysis report, to satisfy the qualification requirements of AP-SIII.9Q, and to facilitate incorporation of the FEP discussions in Section 6.2 into a FEP database. The sources of data, product output, direct input, and references used for the FEP evaluations are cited within the discussion in each of the individual FEP discussions in Section 6.2 of this analysis and its subsections. ANL-WIS-MD-000019 REV 01 6-16 April 2004 6.1.4 Assumptions and Simplifications, Alternative Conceptual Models, and Consideration of Uncertainty in Feature, Event, and Process Screening The generic assumptions used in the System Level FEPs evaluation are provided in Section 5, along with the justification and description of their use. No other assumptions or simplifications are used directly in the FEP analyses unless specifically described in the individual FEP discussions. Simplifications made as part of the FEP analysis, if used, are explained for each FEP in the related FEP discussion presented in Section 6.2 of this analysis report. Specific guidance and criteria for the consideration of alternative conceptual models (including their relationship to FEPs) and the treatment of uncertainty were addressed, as appropriate, following guidance in Appendices A and C of the Scientific Processes Guidelines Manual (SPGM) (BSC 2002 [DIRS 160313]). The issues of alternative conceptual models and uncertainty are addressed in the documentation cited as part of the FEP evaluations. For included System Level FEPs, these alternative conceptual models are then incorporated, or not, into the TSPA-LA model based on their development and evaluation in the cited AMRs. For excluded System Level FEPs, the discussions of the alternative conceptual models from the cited AMRs are summarized in the FEP discussions. The quantification of uncertainty, as described in the SPGM is discussed below for each of the screening criteria: low probability, low consequence, and by regulation. In the case of probability screening arguments, the mean probability of an event (which reflects the range in the underlying uncertainty in supporting information) is used for the evaluation. In no instance has a value less than the mean probability of an event been used as a screening basis for excluding a System Level FEP. If the screening decision is to include a FEP into the performance assessment, and the resulting consequence is to be probabilistically weighted within TSPA-LA, then uncertainty becomes a potentially important consideration in parameter or model development and implementation, per the SPGM (BSC 2002, Appendix A [DIRS 160313]). In the case of low-consequence arguments, it is important to identify the mechanisms or sequence of events that could affect the repository performance and any associated intermediate performance measures. Low-consequence arguments can be postulated using “worst-case” values for the sequence of events and the associated intermediate performance measures. If it can be demonstrated that such values have negligible impact on repository performance, then the issue of uncertainty is addressed by the use of the bounding conditions. However, the use of low-consequence arguments is also subject to uncertainties stemming from substantiated and reasonable alternative conceptual models. Inherent in the evaluation of such alternative conceptual models is a dependence on data, ranges in values and, in some cases, on modeling results that have associated uncertainties. Thus, for low-consequence arguments, consideration of alternative conceptual models and the range in available data and results is more extensively discussed than for probability screening arguments. Alternately, modeling that considers uncertainty and alternative conceptual models, and insignificantly changes the radiological exposure or other measures that are representative of release of radionuclides to the accessible environment, also can be used to support the low-consequence argument. In either case (i.e., use of bounding conditions or use of models and evaluations that explicitly consider uncertainties), ANL-WIS-MD-000019 REV 01 6-17 April 2004 the issue of parameter uncertainty is not as critical for FEPs evaluation, as the consideration of alternative conceptual models (or model form uncertainty). In the case of exclusion of FEPs by regulation, uncertainty (as represented by alternative views of regulatory meaning and intent) cannot be readily quantified. Rather, this type of uncertainty is resolved through the regulatory review and licensing process. Thus, in the System Level FEPs discussions, specific citations to the regulations or regulatory discussions are provided, and the application of the regulations is explicitly expressed for the individual FEPs. 6.1.5 Alternative Approaches, Mathematical Formulations, and Units of Measure Alternative approaches and technical methods for the FEP development and screening process used by YMP are discussed in The Enhanced Plan for Features, Events, and Processes (FEPs) at Yucca Mountain (BSC 2002 [DIRS 158966]). In general, FEP screening involves the comparison of the measure of some feature, event, or process to some threshold level of probability. Mathematical and numerical formulations typically are used to define the probability of the event or process and to define the threshold measure for consequence. For the System Level FEPs, the only mathematical formulation used directly is the analysis of the potential for meteorite impact. The formulation of the probability values, and the relationship of impact effects to damage thresholds in terms of depth of effect, are fully discussed in Attachment IV and constitute a scientific analysis. Depending on the FEP evaluated, the units of measure may vary among FEPs and among cited source documents. In all cases, the units as they appeared in the cited source are provided to allow traceability, and metric equivalents also are provided for consistency and transparency. 6.1.6 Model and Software Issues for Previously Developed and Validated Models No models were used directly in the System Level FEP evaluations, and no software beyond that listed in Section 3 was used in the development of this analysis. The results of models and documents developed by others are cited as the technical basis in some instances (e.g., the human intrusion stylized analysis for TSPA-SR cited from the FEIS (DOE 2002, Section 5.7.1 [DIRS 155970], and published work by Hills and Goda (1993 [DIRS 135281])) that deals with meteorite impact as discussed in Attachment IV. The cited documentation for those models provides an extensive discussion of the formulation of the models, consideration of uncertainty and consideration of alternative conceptual models. 6.1.7 Intended Use and Limitations The intended use of this analysis report is to provide System Level FEP screening information for a project-specific FEP database, and to promote traceability and transparency regarding System Level FEP dispositions. Except as previously noted for some instances of shared FEPs, this analysis report also is intended to be used as the source documentation and to provide the technical basis and the supporting arguments for both included and excluded System Level FEPs. Details of the implementation of included System Level FEPs in TSPA–LA are provided in Section 6.2. For System Level FEPs that are designated for inclusion into the TSPA–LA model, the manner in which the FEP has been included, list of parameters, and any uncertainty ANL-WIS-MD-000019 REV 01 6-18 April 2004 considerations are described. Details of the technical basis for exclusion of System Level FEPs from TSPA–LA also are provided in Section 6.2. Inherent in this evaluation approach is the limitation that the repository will be constructed, operated, and closed according to the design used as the basis for the FEP screening and in accordance with NRC license requirements. This is inherent in performance evaluation of any engineering project, and design verification and performance confirmation are required as part of the construction and operation processes. The results of the FEP screening presented herein are specific to the repository design evaluated in this analysis report for TSPA-LA, particularly for FEPs related to explosions and meteorite impacts. Any changes in direct inputs listed in Section 4.1, in baseline conditions used for this evaluation, or in other subsurface conditions, will need to be evaluated to determine if the changes are within the limits stated in the FEP evaluations. Engineering and design changes are subject to evaluation to determine if there are any adverse manner impacts to safety as codified at 10 CFR 63.73 and in Subparts F and G ([DIRS 156605]). See also the requirements at 10 CFR 63.44 and 10 CFR 63.131 ([DIRS 156605]). 6.2 SYSTEM LEVEL FEATURE, EVENT, AND PROCESS SCREENING AND ANALYSES This section addresses the 33 FEPs that have been identified as System Level FEPs for TSPA-LA. The FEPs have been organized into four groups: Assessment Basis and Modeling Requirement FEPs (Section 6.2.1), Process and Site Control FEPs (Section 6.2.2), Human Intrusion FEPs (Section 6.2.3), and Miscellaneous Geologic and Astronomic FEPs (Section 6.2.4). Within each group, the FEPs are addressed in numeric order based on the FEP number. Appendices pertaining specifically to System Level FEPs include Appendices I, II, III, and IV. Attachment I is a glossary. Attachment II provides data qualification documentation for direct inputs being qualified and used within this work product. Attachment III is an analysis of the timing of human intrusion without recognition by the intruder. Attachment IV is an expanded discussion of meteorite-related FEPs, including the mathematical formulation for determining the probability of various impacts and cratering effects. 6.2.1 Assessment Basis and Modeling Issue Features, Events, and Processes This set of FEPs is related to the regulatory framework, modeling, and design basis used for the performance assessment. All direct inputs used in this Section originated from YMP-controlled sources or NRC regulations and are listed in Section 4 and its subsections. No further discussion beyond that provided in Section 4 is required. ANL-WIS-MD-000019 REV 01 6-19 April 2004 6.2.1.1 Timescales of Concern (0.1.02.00.0A) FEP Description: This FEP addresses the timescale of concern over which the disposal system presents a significant health or environmental hazard. Descriptor Phrases: Timescale of concern Screening Decision: Included Screening Argument: Not Applicable TSPA Disposition: “Timescales of concern” is Included in the TSPA–LA by analyzing performance for a 10,000-year period, as required by the NRC. The timescale of concern has been set by the NRC at 10 CFR 63.303 [DIRS 156605]. That section of the regulation states that compliance is to be based upon the mean of the distribution of projected doses of DOE’s performance assessments which project the performance of the Yucca Mountain disposal system for 10,000 years after disposal. A 10,000-year timescale is consistent with the criteria established for “low probability” at 10 CFR 63.114(d) ([DIRS 156605]), and also consistent with the requirement at 10 CFR 63.305(c) ([DIRS 156605]) that states that DOE must vary factors relating to the geology, hydrology, and climate that could affect the Yucca Mountain disposal system in the next 10,000 years. A 10,000-year period is also specified as a basis of consideration at 10 CFR 63.321 ([DIRS 156605]) for treatment of the human intrusion stylized analysis. At 10 CFR 63.341 ([DIRS 156605]), the NRC requires that as part of the performance assessment DOE provide, in the environmental impact statement, peak dose information after 10,000 years following disposal. However, the regulation specifically states that no regulatory standard applies to the results of this analysis. As stated in the Total System Performance Assessment-License Application Methods and Approach (BSC 2003, Section 1.3 [DIRS 166296]), “The regulatory time period of analysis for the compliance evaluation is 10,000 years. However, the TSPA analyses are intended to extend beyond 10,000 to 20,000 years. This is intended to provide a basis for evaluating whether uncertainties in results after 10,000 years affect compliance during the regulatory performance period. Likewise, the FEPs for these analyses will not go beyond 10,000 years.” Furthermore, Total System Performance Assessment-License Application Methods and Approach (BSC 2003 Section 9.1 [DIRS 166296]) states that, “Current plans are to analyze simulations up to 20,000 years, and to utilize 300 realizations per analysis. These plans may be modified for various reasons as the analyses progress.” The TSPA for the final environmental impact statement (FEIS) (herein referred to as the TSPA-FEIS model) evaluated doses over longer periods (up to one million years) (DOE 2002 [DIRS 155970]). ANL-WIS-MD-000019 REV 01 6-20 April 2004 Related Documents: Total System Performance Assessment-License Application Methods and Approach (BSC 2003 [DIRS 166296]) Final Environmental Impact Statement for a Geologic Repository for the Disposal of Spent Nuclear Fuel and High-Level Radioactive Waste at Yucca Mountain, Nye County, Nevada DOE/EIS-0250 (DOE 2002 [DIRS 155970]) Related FEPs: Regulatory requirements and exclusions (0.1.09.00.0A) Model and data issues (0.1.10.00.0A) Early failure of waste packages (2.1.03.08.0A) Early failure of drip shields (2.1.03.08.0B) Radioactive decay and ingrowth (3.1.01.01.0A) Supplemental Discussion: Table 6-2. Indirect Inputs for Timescales of Concern (0.1.02.00.0A) Reference Input BSC 2003, Sections 1.3 and 9.1 [DIRS 166296] Modeling to be performed out to 20,000 years DOE 2002 [DIRS 155970] Modeling past to 10,000 years for peak dose 6.2.1.2 Spatial Domain of Concern (0.1.03.00.0A) FEP Description: This FEP addresses the spatial domain of concern over which the disposal system may present a significant health or environmental hazard. Descriptor Phrases: Spatial domain of concern Screening Decision: Included Screening Argument: Not Applicable TSPA Disposition: “Spatial domain of concern” is included in the TSPA–LA by specifying the spatial boundary conditions for the various models used in the performance assessment and those used in the environmental impact statement. The spatial domain of concern is a function of the analysis that is being performed. The model-specific spatial domain considered in the TSPA–LA model varies according to the phenomenon being considered. For instance, the spatial domain of concern for a regional groundwater flow model and the geologic setting is bounded on a regional scale, while the analysis of waste package damage occurs at the scale of a single waste package, with specific corrosion phenomena being considered at the fracture and pitting level. Individual model ANL-WIS-MD-000019 REV 01 6-21 April 2004 domains are described in the documentation of each component of the TSPA model and in individual AMRs. The spatial domain encompassed and evaluated explicitly in the TSPA model extends from the land surface through the unsaturated zone, through the repository, into the saturated zone, and laterally away from the repository to the location of the RMEI. This encompasses the eight primary model components and submodels described and illustrated in Section 5.1 of the Total System Performance Assessment-License Application Methods and Approach (BSC 2003 [DIRS 166296]). A significant health or environmental hazard may not be present throughout the entire area, but the entire area is considered to be within the domain of spatial concern of the performance assessment. The potential for environmental impact has been addressed in the FEIS (DOE 2002 [DIRS 155970]) and is not further addressed in the TSPA-LA. From a regulatory standpoint, the spatial domain of concern wherein there is a potential for a significant health or environmental hazard is primarily defined by the location of the RMEI. In practical application, this spatial domain could extend approximately 18 km in the direction of groundwater flow (generally in a southerly direction) and extends no more than 5 km from the repository footprint in any other direction (i.e., the spatial domain defines the extend [is this word correct?] of the controlled area to the location of the RMEI). As described in Section 4.1.3 above, and as specified at 10 CFR 63.312(a) [DIRS 156605]), the RMEI… Lives in the accessible environment above the highest concentration of radionuclides in the plume of contamination The accessible environment is defined at 10 CFR 63.302 ([DIRS 156605]) by the definition of the controlled area. Accessible environment means any location outside the controlled area. The controlled area is defined in the same section of the regulations as: (1) The surface area, identified by passive institutional controls, that encompasses no more than 300 km2. It must not extend farther: South than 36° 40' 13.6661. north latitude, in the predominant direction of groundwater flow; and Than 5 km from the repository footprint in any other direction; and (2) The subsurface underlying the surface area. The preamble in the regulations for 40 CFR Part 197 (66 FR 32074, p. 32117 [DIRS 155216]) states further that: If fully employed by DOE, and based on current repository design, the controlled area could extend approximately 18 km in the direction of ground water flow ANL-WIS-MD-000019 REV 01 6-22 April 2004 (presently believed to be in a southerly direction) and extend no more than 5 km from the repository footprint in any other direction. As stated in the Total System Performance Assessment-License Application Methods and Approach (BSC 2003, Section 9.1 [DIRS 166296]), “The probabilistic simulations of the total system will be evaluated to determine the key factors contributing to the dose at 18 km.” Related Documents: Total System Performance Assessment-License Application Methods and Approach (BSC 2003 [DIRS 166296]) Final Environmental Impact Statement for a Geologic Repository for the Disposal of Spent Nuclear Fuel and High-Level Radioactive Waste at Yucca Mountain, Nye County, Nevada DOE/EIS-0250 (DOE 2002 [DIRS 155970]) Related FEPs: Regulatory requirements and exclusions (0.1.09.00.0A) Model and data issues (0.1.10.00.0A) Supplemental Discussion: Table 6-3. Indirect Inputs for Spatial Domain of Concern (0.1.03.00.0A) Reference Input BSC 2003, Sections 5.1 and 9.1 [DIRS 166296]) Descriptions of models and model domains DOE 2002 [DIRS 155970] Potential for environmental impact within the model domain 6.2.1.3 Regulatory Requirements and Exclusions (0.1.09.00.0A) FEP Description: This FEP addresses regulatory requirements and guidance specific to the Yucca Mountain repository. Descriptor Phrases: Regulatory criteria Screening Decision: Included Screening Argument: Not Applicable TSPA Disposition: “Regulatory requirements and exclusions” is intrinsically Included in the TSPA–LA due to the governing nature of the federal regulations and the mandated licensing process. Federal regulations applicable to the long-term performance of the disposal system are described at 10 CFR Part 63 ([DIRS 156605]), and incorporate the requirements of 40 CFR Part 197 ([DIRS 165519]). Regulatory requirements and exclusions provide the framework within which the TSPA is conducted. They define the performance criteria and ANL-WIS-MD-000019 REV 01 6-23 April 2004 provide assumptions that must be used in the evaluation (e.g., timescale of concern, characteristics of the reference biosphere, specification of a human-intrusion stylized analysis, limits on release to the accessible environment). They provide guidance on the FEPs that must be considered (i.e., exclusion of low-probability and low-consequence events and processes) and limit the range of conditions that must be considered (e.g., “consistent with present knowledge of natural processes”). The various aspects of the repository including design, construction, operation, and preclosure and postclosure performance must be shown to comply with regulatory requirements. If not, the repository will not be licensed, construction may be prohibited, operations may be halted until deficiencies are corrected, or further operations or closure activities will be delayed until deficiencies are corrected. At 10 CFR 63.303 [DIRS 156605), the NRC is stated as being responsible for determining compliance “based upon the mean of the distribution of projected doses of DOE’s performance assessments which project the performance of the Yucca Mountain disposal system for 10,000 years after disposal.” DOE must demonstrate a reasonable expectation that the Postclosure Individual-Protection Standard, Human-Intrusion Standard, and Ground-Water Protection Standard will not be exceeded. Evaluation of compliance to these standards is a primary objective of the TSPA. The criteria and assumptions to be used in making the evaluation are provided in the various referenced sections at 10 CFR Part 63 ([DIRS 156605]) and at 40 CFR Part 197 ([DIRS 165519]) and, as applicable to FEP screening, are listed in Section 4.2 of this analysis report. These criteria and assumptions are regulatory requirements and have been incorporated into the TSPA model either using specified characteristics to guide selection of input parameters (such as the characteristics of the RMEI) or by consideration of a range of possible climatic and geologic settings consistent with present knowledge of natural processes. In a more general sense, compliance with regulatory requirements has been identified in the PRD (Canori and Leitner 2003 [DIRS 166275]). The PRD was developed as part of Configuration Management as described in the YMP Configuration Management Plan (BSC 2004 [DIRS 168396]). The PRD is used to implement the Requirements Management Plan (DOE 2003 [DIRS 165181]). The PRD documents and categorizes the regulatory requirements and other project requirements, and it provides a crosswalk to the various YMP organizations that are responsible for ensuring that the criteria have been addressed in the LA. The regulatory requirements include criteria relevant to performance assessment activities, and the regulatory requirements have been mapped to specific technical activities being performed for license application. These criteria find expression as specific acceptance criteria presented by the NRC in NUREG-1804 (NRC 2003 [DIRS 163274]), which will be used by the NRC during the licensing process to evaluate whether regulatory requirements have been adequately addressed. ANL-WIS-MD-000019 REV 01 6-24 April 2004 Related Documents: Project Requirements Document (Canori and Leitner 2003 [DIRS 166275]) Related FEPs: Regulatory requirements and exclusions provide the framework within which the TSPA is conducted. They define the performance criteria and provide assumptions that must be used in the evaluation (e.g., characteristics of the reference biosphere, specification of a human-intrusion stylized analysis). Consequently, in that sense, all FEPs are related to this FEP. A partial list of related FEPs includes: Timescales of concern (0.1.02.00.0A) Spatial domain of concern (0.1.03.00.0A) Social and institutional developments (1.4.08.00.0A) Supplemental Discussion: Table 6-4. Indirect Inputs for Regulatory Requirements and Exclusions (0.1.09.00.0A) Reference Input NRC 2003 [DIRS 163274] NRC Review Criteria BSC 2004 [DIRS 168396] Management Plan DOE 2003 [DIRS 165181] Management Plan NRC = U.S. Nuclear Regulatory Commission 6.2.1.4 Model and Data Issues (0.1.10.00.0A) FEP Description: This FEP addresses issues related to modeling of the disposal system. Model and data issues are general (i.e., methodological) issues affecting the assessment modeling process and use of data. These issues include the approach and assumptions associated with the selection of conceptual models, the mathematical implementation of conceptual models, model geometry and dimensionality, models of coupled processes, and boundary and initial conditions. These issues also include the derivation of data values and correlations. Descriptor Phrases: Model issues (geometry, boundary conditions, initial conditions, uncertainties, conceptual models); Data issues (uncertainty, correlation). Screening Decision: Included Screening Argument: Not Applicable TSPA Disposition: Model and data requirements are addressed specifically at 10 CFR 63.114 ([DIRS 156605]) and are included in the TSPA-LA ANL-WIS-MD-000019 REV 01 6-25 April 2004 as described in the document Total System Performance Assessment-License Application Methods and Approach (BSC 2003 [DIRS 166296]). The specifications at 10 CFR 63.114 (a, b, c, and g) [DIRS 156605] pertinent to this FEP include the following clauses: “(a) Include data related to the geology, hydrology, and geochemistry (including disruptive processes and events) of the Yucca Mountain site, and the surrounding region to the extent necessary, and information on the design of the engineered barrier system, used to define parameters and conceptual models used in the assessment.” “(b) Account for uncertainties and variability in parameter values.” Several kinds of uncertainties are distinguished and receive somewhat different treatments. In general, the TSPA–LA has grouped these as parameter uncertainty and model form uncertainty. The TSPA recognizes and accounts for parameter uncertainty, where appropriate, and intends to provide the regulators with a basis for a “reasonable expectation” of compliance. “(c) Consider alternative conceptual models of features and processes.” In many of the subsystems of the overall TSPA system, there are plausible alternative models or assumptions, which result in model form uncertainty. In some cases, these alternative models form a continuum, and sampling from the continuum of assumptions fits naturally within the Monte Carlo framework of sampling from probability distributions. In other cases, the assumptions or models are based on discrete choices. Two possible approaches to incorporating alternative models within the TSPA include 1) weighting all models into one comprehensive Monte Carlo simulation (lumping), or keeping the discrete models separate and performing multiple Monte Carlo simulations for each discrete model (splitting). There are advantages and disadvantages to both approaches. A combination of the two approaches is being used. “(g) Provide the technical basis for models used in the performance assessment such as comparisons made with outputs of detailed process-level models and/or empirical observations.” Each of the models used in developing the TSPA has been documented according to project-specific QA procedures for model development, validation, and use. Model selection, use, verification, and inputs are addressed in the individual modeling reports. The document Total System Performance Assessment-License Application Methods and Approach (BSC 2003 [DIRS 166296]) outlines the use of various model components that consider the geologic, hydrologic and geochemical data (Section 5.1), parameter uncertainty (Section 3.5), alternative conceptual models (Section 3.3), and abstractions (Section 3.4). The ANL-WIS-MD-000019 REV 01 6-26 April 2004 TSPA–LA Model validation approach is outlined in Section 7 and the approach for uncertainty analysis is provided in Section 8.1 of that document. Additionally, each of the models used in developing the TSPA has been documented in a stand-alone modeling report per project-specific QA procedures. The modeling reports address model selection, model development, verification, validation, inputs and use. These modeling reports were prepared per the guidelines for model documentation and the specific guidance and criteria for the consideration of alternative conceptual models (including their relationship to FEPs) and the treatment of uncertainty as provided in Appendices A and C of the SPGM (BSC 2002 [DIRS 160313]). The list of regulatory specifications for the performance assessment germane to model and data issues requires the consideration of data on the geology, hydrology, and geochemistry (including disruptive processes and events), consideration of uncertainty, the consideration of alternative conceptual models, and providing the technical basis of any models used. Related Documents: Total System Performance Assessment-License Application Methods and Approach (BSC 2003 [DIRS 166296]) Related FEPs: This FEP is broad in its definition. Consequently, the following list of related FEPs is not exhaustive. The listed FEPs were chosen based on elements within the FEP description (geometry and dimensionality, coupled processes, boundary and initial conditions). Any FEP addressed by models could potentially have been included within the list. Timescales of concern (0.1.02.00.0A) Spatial domain of concern (0.1.03.00.0A) General corrosion of waste packages (2.1.03.01.0A) General corrosion of drip shields (2.1.03.01.0B) Mechanical impact on waste package (2.1.03.07.0A) Mechanical impact on drip shields (2.1.03.07.0B) Chemical effects at EBS component interfaces (2.1.06.07.0A) Mechanical effects at EBS component interfaces (2.1.06.07.0B) Locally saturated flow at bedrock/alluvium contact (2.2.07.01.0A). Thermo-mechanical stresses alter characteristics of fractures near repository (2.2.10.04.0A) Thermo-mechanical stresses alter characteristics of faults near repository (2.2.10.04.0B) Thermo-mechanical stresses alter characteristics of rocks above and below repository (2.2.10.05.0A) Thermo-chemical alteration in the UZ (solubility, speciation, phase changes, precipitation/dissolution) (2.2.10.06.0A) Thermo-chemical alteration in the SZ (solubility, speciation, phase changes, precipitation/dissolution (2.2.10.08.0A) ANL-WIS-MD-000019 REV 01 6-27 April 2004 Supplemental Discussion: Table 6-5. Indirect Inputs for Model and Data Issues (0.1.10.00.0A) Reference Input BSC 2002, Appendices A and C [DIRS 160313] Guidelines for model documentation 6.2.1.5 Repository Design (1.1.07.00.0A) FEP Description: This FEP addresses the consideration of the design of the repository and the ways in which the design contributes to long- term performance. The performance assessment must account for design features, material characteristics, and the ways in which the design influences the evolution of the in-drift environment. Descriptor Phrases: Design control (implemented) Design modification Construction materials Quality control (implemented) Screening Decision: Included Screening Argument: Not Applicable TSPA Disposition: “Repository design” and potential design modifications are Included in the TSPA–LA because the repository design is the basis of the models used for the performance assessment. The approach for including design elements is outlined in Section 5.1 of the Total System Performance Assessment-License Application Methods and Approach (BSC 2003 [DIRS 166296]). Particularly applicable to this FEP are the model components for the EBS, Waste Package and Drip Shield Degradation, Waste Form Degradation and Mobilization, and EBS Flow and Transport. These model components take into account the physical dimensions, material characteristics, and evolution of the in-drift environment—all of which stem directly from design considerations. The design elements are included as nominal-scenario class parameters used to define the physical dimensions, the characteristics, and the long-term behavior of the waste form, waste packages, and EBS. Any design modifications are required to be analyzed for potential impact. The incorporation of repository design information into the framework of the various TSPA-LA model components has been accomplished using of a series of information exchange drawings (IEDs), which are cited as needed in the individual model AMRs. The IEDs contain information regarding material characteristics and properties, component dimensions, and component performance under various conditions (e.g., corrosion rates, seismic response, damage areas). The use of these design drawings is discussed in each model AMR, as applicable. ANL-WIS-MD-000019 REV 01 6-28 April 2004 Inherent in the performance assessment modeling of engineered systems is that there are failure rates, or times-to-failure, associated with the systems and that there are interactions of the engineered systems with the natural systems. Such baseline failure rates are identified in the related FEP 2.1.03.08.0A (early failure of waste packages) and specifically include the consideration of manufacturing and welding defects within the waste package degradation analysis. Deficiencies beyond those specifically included in the cited FEP are addressed under FEP 1.1.08.00.0A (inadequate quality control and deviations from design). Furthermore, 10 CFR Part 63 Subpart F ([DIRS 156605]) provides a list of specifications for a performance confirmation program to provide data related to conditions encountered and changes in those conditions, functioning of the natural engineered systems, and monitoring and testing. A performance confirmation plan is documented in Snell et al. (2003 [DIRS 166219]). Modifications and/or deviations from the TSPA-LA design are subject to regulatory requirements that address deliberate changes and modifications. The manner in which DOE must address changes and by which the NRC is informed of the changes is codified at 10 CFR 63.44 ([DIRS 156605]). As indicated in 10 CFR 63.142 (d) ([DIRS 156605]), deviations from quality standards must be controlled. Related Documents: None Related FEP: Inadequate quality control and deviations from design (1.1.08.00.0A) Supplemental Discussion: There are no indirect inputs for this analysis. 6.2.1.6 Retrievability (1.1.13.00.0A) FEP Description: This FEP addresses design, emplacement, operational, or administrative measures that might be applied or considered in order to enable or ease retrieval of wastes. There may be a requirement to retrieve all or part of the waste stored in the repository, for example, to recover valuable fissile materials or to replace defective containers. Descriptor Phrases: Waste emplacement (retrievability) Screening Decision: Included Screening Argument: Not Applicable ANL-WIS-MD-000019 REV 01 6-29 April 2004 TSPA Disposition: “Retrievability” is a performance objective of the repository as specified at 10 CFR 63.111(e)(1, 2, and 3) [DIRS 156605]), and features are included in the design to allow for retrievability. The regulation specifies that the repository be designed in such a way that it preserves “…the option of waste retrieval throughout the period during which wastes are being emplaced…so that any or all of the emplaced waste could be retrieved on a reasonable schedule starting at any time up to 50 years after waste emplacement operations are initiated…” (10 CFR 63.111 (e) (1, 2, and 3), [DIRS 156605]). This precludes further FEP consideration for resource recovery and retrieval past 50 years after waste emplacement (see the Supplemental Discussion for other a discussion of limitations). Regardless, the repository design is part of the basis of the postclosure evaluation, and aspects of the repository design related to waste retrievability are, therefore, implicitly considered as part of the basis for the TSPA modeling and have been included as noted in FEP 1.1.07.00.0A (repository design). The design elements related to retrievability include dimensions of the drifts, design of the emplacement system, and waste package design. The incorporation of repository design information into the framework of the various TSPA-LA model components has been accomplished using of a series of IEDs, which are cited as needed in the individual model AMRs. The IEDs contain information regarding material characteristics and properties, component dimensions, and component performance under various conditions (e.g., corrosion rates, seismic response, damage areas). The approach for including design elements is further outlined in Section 5.1 of the Total System Performance Assessment-License Application Methods and Approach (BSC 2003 [DIRS 166296]). Particularly applicable to this FEP are the model components for the EBS, waste package and drip shield degradation, waste form degradation and mobilization, and EBS flow and transport. Retrievability is thereby implicitly “Included” in the TSPA. Supplemental Discussion–The objective of the performance assessment is to evaluate compliance with the “postclosure” performance objective per 10 CFR 63.102(j) ([DIRS 156605]). The operational and administrative considerations of "retrievability" are a preclosure consideration and are, therefore, beyond the scope of the performance assessment. Furthermore, postclosure retrieval of wastes or other repository-system components for the purpose of resource recovery was addressed by the NRC in the Supplementary Information for 10 CFR Part 63 (66 FR 55732 , III. Public Comments and Response, 2.2 Retrievability, Issue 2, p. 55743 [DIRS 156671]). To wit: …the Commission has previously noted that its retrieval provision is not intended to facilitate recovery. Waste retrieval is intended to be an unusual event only to be undertaken to protect public health and safety. Table 6-6. Indirect Inputs for Retrievability (1.1.13.00.0A) Reference Input 10 CFR 63.102(j) ([DIRS 156605] Performance assessment is to address postclosure 10 CFR Part 63 [DIRS 156605] Regulatory intent regarding retrieval Related Documents: None ANL-WIS-MD-000019 REV 01 6-30 April 2004 Related FEPs: Repository design (1.1.07.00.0A) Inadequate quality control and deviations from design (1.1.08.00.0A) Accidents and unplanned events during construction and operation (1.1.12.01.0A) Deliberate human intrusion (1.4.02.01.0A) Mining and other underground activity (human intrusion) (1.4.05.00.0A) 6.2.1.7 Repository-Scale Spatial Heterogeneity of Emplaced Waste (2.1.01.04.0A) FEP Description: Waste placed in Yucca Mountain will have physical, chemical, and radiological properties that will vary spatially, resulting in variation in the mass of radionuclides available for transport from different parts of the repository. Descriptor Phrases: Drift-scale spatial heterogeneity of waste packages; Repository-scale spatial heterogeneity of waste. Screening Decision: Included Screening Argument: Not Applicable TSPA Disposition: Heterogeneity of the waste inventory is discussed under FEP 2.1.01.03.0A. The heterogeneity is greater for DOE spent nuclear fuel (DSNF) and high-level waste (HLW) glass inventories than for commercial spent nuclear fuels (CNSF). At the repository scale, waste form degradation and mobilization in the TSPA-LA model is addressed using three generic waste forms: (1) commercial spent nuclear fuel (CSNF), which for modeling purposes also addresses naval spent nuclear fuel, (2) DOE-owned spent nuclear fuel (DSNF), and (3) DOE high-level radioactive waste glass (DHLW). These three generic categories of waste will be contained and disposed in two types of waste packages—CSNF waste packages and codisposal waste packages, with the latter containing both DSNF and DHLW glass. For scenarios in which only a few packages breach, the package-to-package heterogeneity could be important in quantifying exposure of the RMEI. For postclosure TSPA, however, these “few-package” scenarios are not significant to performance because only scenarios with many packages breached show calculated releases that approach the exposure limit. For multiple-package breach scenarios, package-to-package heterogeneity is directly addressed in the TSPA-LA using uncertainty parameters for the average inventory within the CSNF and codisposal packages (BSC 2003, Table 19, FEP 2.1.03.01.0A [DIRS 161961]). At the repository-scale, radionuclide dissolution and release depend more directly on infiltration than on the specific location within the repository, Accordingly, waste forms are treated as generic categories (BSC 2003, pp. 71-73 [DIRS 166296]) and, within the TSPA-LA model, the varying generic waste types are coupled to spatial variations in infiltration properties rather than ANL-WIS-MD-000019 REV 01 6-31 April 2004 to specific location (BSC 2003, pp. 77-78 [DIRS 166296]). More specifically, the process of waste form degradation will be modeled by equations using empirical degradation rate formulas for the three different generic waste form types: CSNF, DSNF, and HLW. Output will be the mass of waste form exposed versus time and the volume of water in contact with the waste form versus time, which will be used to populate several waste form cells in the model that correspond to different waste form types and seepage cases. The amount of inventory that can ultimately enter each waste form cell will be a linear function of the number of packages emplaced in each inventory, seepage, and thermal hydrologic environment (BSC 2003, p. 81 [DIRS 166296]). The potential effect of waste heterogeneity at the drift-scale is addressed by including various seepage and thermal hydrologic environments at the repository scale. Because the repository- scale heterogeneities are addressed in the above manner, this FEP is considered as explicitly included. Supplemental Discussion: Table 6-7. Indirect Inputs for Repository-Scale Spatial Heterogeneity of Emplaced Waste (2.1.01.04.0A) Reference Input BSC 2003, Table 19 [DIRS 161961] Waste inventory heterogeneity 6.2.2 Process and Site-Control Features, Events, and Processes This set of FEPs addresses quality control processes, site-control and institutional-control related issues, and site operational concerns that may have a potential for impact on postclosure performance. All direct inputs used in this section originated from YMP-controlled sources or NRC regulations and are listed in Section 4 and its subsections. No further discussion beyond that provided in Section 4 is required. 6.2.2.1 Records and Markers for the Repository (1.1.05.00.0A) FEP Description: This FEP addresses the retention of records of the contents of the repository and markers constructed to inform future humans of the location and contents of the repository. Performance assessments must consider the potential effects of human activities that might take place within the controlled area at a future time when institutional controls and/or knowledge of the presence of a repository cannot be assumed. Descriptor Phrases: Records and markers on site Screening Decision: Excluded – By Regulation Screening Argument: “Records and Markers for the Repository” is excluded from the TSPA–LA by regulation. At 10 CFR 63.102(k) [DIRS 156605]), the regulation addresses the use of institutional controls. The regulation requires that both passive and active institutional ANL-WIS-MD-000019 REV 01 6-32 April 2004 controls are to be maintained, but also indicates that it is not possible to make sound forecasts regarding their long-term reliability. The requirements for constructing monuments, preserving and archiving records, and oversight are listed at 10 CFR 63.51(a)(3)(i-iii) and at 10 CFR 63.72(a) and (b)(1-11) ([DIRS 156605]). Land ownership and control requirements are specified by 10 CFR 63.121 ([DIRS 156605]). The markers and repository archives will persist for some portion of the regulatory period, but for the analyses, they are assumed ineffective, in accordance with the regulatory requirements. See Assumption 5.2 of this analysis report. At 10 CFR 63.102(k) ([DIRS 156605]), the NRC recognizes that institutional controls are expected to reduce significantly, but not eliminate, the potential for human activity that causes or accelerates the release of radioactive material. To eliminate further speculation on how to address the effectiveness of these controls the regulation states: However, because it is not possible to make scientifically sound forecasts of the long-term reliability of institutional controls, it is not appropriate to include consideration of human intrusion into a fully risk-based performance assessment for purposes of evaluating the ability of the geologic repository to achieve the performance objective. Accordingly, for those FEPs addressing administrative controls, and particularly their influence on human intrusion, the FEPs have been excluded, by regulation, from consideration in the human intrusion stylized analysis. On that basis, the consideration of the timing of occurrence of human intrusion without recognition (see Attachment III of this analysis report) is based only on the physical properties of the drip shields and waste packages past 10,000 years, rather than on any consideration of administrative control, planning restrictions, repository markers, or an information repository. Although these institutional controls will be implemented, they do not influence the calculated timing or determination of the likelihood of a human intrusion, and therefore make no difference to the resulting dose to the RMEI or to the release of radionuclides to the accessible environment as addressed by the TSPA–LA model. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Administrative control of repository site (1.1.10.00.0A) Deliberate human intrusion (1.4.02.01.0A) Inadvertent human intrusion (1.4.02.02.0A) Unintrusive site investigation (1.4.03.00.0A) Drilling activities (human intrusion) (1.4.04.00.0A) Mining and other underground activities (1.4.05.00.0A) Social and institutional developments (1.4.08.00.0A) ANL-WIS-MD-000019 REV 01 6-33 April 2004 Wild and natural land use and water use (2.4.08.00.0A) Agricultural land use and water use (2.4.09.01.0B) Urban and industrial land and water use (2.4.10.00.0A) Supplemental Discussion: Table 6-8. Indirect Inputs for Records and Markers for the Repository (1.1.05.00.0A) Reference Input 10 CFR 63.51(a)(3)(i-iii) [DIRS 156605] Requirements for monuments and archives 10 CFR 63.72(a) and (b)(1-11) [DIRS 156605] Requirements for monuments and archives 10 CFR 63.121 [DIRS 156605] Requirements for land ownership and control 6.2.2.2 Inadequate Quality Control and Deviations from Design (1.1.08.00.0A) FEP Description: This FEP addresses issues related to inadequate quality assurance and control procedures and inadequate testing during the design, construction, and operation of the repository. It also includes inadequacy in the manufacture of the waste forms, containers, and engineered features. Lack of quality control could result in a poorly designed repository, unmodeled design features, deviations from design, material defects, faulty waste package fabrication, and faulty or non-design standard construction. All of these may lead to reduction in the effectiveness of the engineered barriers. Descriptor Phrases: Design control (inadequate) Quality control (inadequate); Defects Deviations from design. Screening Decision: Excluded – Low Consequence Screening Argument: “Inadequate Quality Control and Deviations from Design” is excluded from the TSPA–LA based on low consequence because the regulatory requirements for performance confirmation (10 CFR 63 Subpart F [DIRS 156605] and quality assurance (10 CFR Subpart G [DIRS 156605]) require that any deviation from design be evaluated for potential impact, and that significant deviations which are detected during the operational period be corrected (10 CFR 63.73a [DIRS 156605]). This FEP description is focused on the lack of quality control processes. As discussed in Section 6.1.7 of this analysis report, inherent in the FEPs evaluation approach is the limitation that the repository will be constructed, operated, and closed according to the design used as the basis for the FEP screening and in accordance with NRC license requirements. This is an inherent limitation for performance evaluation of any engineering project, and design verification ANL-WIS-MD-000019 REV 01 6-34 April 2004 and performance confirmation are required as part of the construction and operation processes. Design verification during the operational period is the subject of an extensive performance confirmation plan documented in Snell et al. (2003 [DIRS 166219]). Furthermore, 10 CFR Part 63 ([DIRS 156605]) provides a list of requirements that have been incorporated into the performance confirmation program to provide data related to encountered subsurface conditions, functioning of the natural and engineered systems, and monitoring and testing. The performance confirmation program is documented in Snell et al. (2003 [DIRS 166219]). Modifications and/or deviations from the TSPA-LA design are subject to regulatory requirements and review that address deliberate changes and modifications. The manner in which DOE must address changes and by which the NRC is informed of the changes is codified at 10 CFR 63.44 ([DIRS 156605]). As indicated in 10 CFR Subpart G [DIRS 156605], the quality control program (including design control, procurement and materials control, inspections, and handling, storage, and shipping controls) is to be applied to all systems, structures, and components important to safety and to design and characterization of barriers important to waste isolation. Furthermore, deviations from quality standards and the design basis must be controlled. At 10 CFR 63.73(a) ([DIRS 156605]), the NRC requires prompt notification if there is a significant deficiency found in (1) the characteristics of the Yucca Mountain site, or (2) design and construction of the geologic repository area, including significant deviations from the design criteria and design bases stated in the application. Significant deviations that are detected during the operational period will be evaluated, and as needed, corrected. Any residual defects or fabrication or construction deficiencies, therefore, will be of a minor nature and will not lead to significant effects on the repository performance. Compliance with these requirements ensures a low consequence (it is unlikely that there will be significant effects from undetected deviations) in the event that the design is not followed. Regardless of the requirements of the quality assurance and performance confirmation programs, the TSPA allows for the possibility that engineered systems may not perform entirely as designed for the full 10,000 years, through the probabilistic treatment of waste-package and drip shield degradation. Some qualitative understanding of the effect of deficiencies can be taken from the multiple barrier analyses to be performed as part of the TSPA–LA modeling activities (BSC 2003, Section 8.3 [DIRS 166296]). The qualitative understanding can be further supplemented with a quantitative measure provided by barrier neutralization analyses as described in Appendix D.3 of Total System Performance Assessment-License Application Methods and Approach (BSC 2003 [DIRS 166296]). TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Undesirable materials left (1.1.02.03.0A) Error in waste emplacement (1.1.03.01.0A) Error in backfill emplacement (1.1.03.01.0B) ANL-WIS-MD-000019 REV 01 6-35 April 2004 Incomplete closure (1.1.04.01.0A) Repository design (1.1.07.00.0A) Accidents and unplanned events during construction and operation (1.1.12.01.0A) Retrievability (1.1.13.00.0A) Degradation of cladding from waterlogged rods (2.1.02.11.0A) Early failure of waste packages (2.1.03.08.0A) Early failure of drip shields (2.1.03.08.0B) Supplemental Discussion: Table 6-9. Indirect Inputs for Inadequate Quality Control and Deviations from Design (1.1.08.00.0A) Reference Input BSC 2003, Section 8.3 and Appendix D.3 Barrier neutralization analyses [DIRS 166296] 6.2.2.3 Schedule and Planning (1.1.09.00.0A) FEP Description: This FEP addresses the sequences of events and activities occurring during construction, operation, and closure of the repository. Deviations from the design, construction, or waste emplacement schedule may affect the long-term performance of the disposal system. Descriptor Phrases: Schedule and planning; Delays; Phased operations. Screening Decision: Excluded: By Regulation Screening Argument: “Schedule and Planning” is excluded from the TSPA–LA by regulation because the stated regulatory objective is postclosure performance assessment, whereas scheduling and planning are preclosure operational issues (10 CFR 63.102(j) ([DIRS 156605]). Events related to changes in the construction, operation, or closure schedule are outside the scope of the TSPA and would need to be evaluated as design modifications should they occur. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: None Supplemental Discussion: There are no indirect inputs for this analysis. ANL-WIS-MD-000019 REV 01 6-36 April 2004 6.2.2.4 Administrative Control of Repository Site (1.1.10.00.0A) FEP Description: This FEP addresses administrative control of the repository site. Administrative control can reduce the potential for detrimental or unplanned human activities within the controlled area that could inadvertently cause or accelerate the release of radioactive material. Descriptor Phrases: Institutional control of site Screening Decision: Excluded – By Regulation Screening Argument: “Administrative control of the repository site” is excluded from the TSPA–LA by regulation. At 10 CFR 63.102(k) ([DIRS 156605]), the regulations address the use of institutional controls. The regulations require that both passive and active institutional controls be maintained, but not relied upon for performance. The requirements for constructing monuments, preserving and archiving records, and oversight are listed at 10 CFR 63.51(a)(3)(i-iii) and at 10 CFR 63.72(a) and (b)(1-11) [DIRS 156605]). Land ownership and control requirements are specified at 10 CFR 63.121 ([DIRS 156605]). The markers and repository archives will persist for some portion of the regulatory period, but for the analyses, they are assumed ineffective (see Assumption 5.2 of this analysis report) in accordance with the regulatory requirements. At 10 CFR 63.102(k) ([DIRS 156605]), the NRC recognizes that institutional controls are expected to reduce significantly, but not eliminate, the potential for human activity that causes or accelerates the release of radioactive material. To eliminate further speculation on how to address the effectiveness of these controls the regulation states: However, because it is not possible to make scientifically sound forecasts of the long-term reliability of institutional controls, it is not appropriate to include consideration of human intrusion into a fully risk-based performance assessment for purposes of evaluating the ability of the geologic repository to achieve the performance objective. Accordingly, for those FEPs addressing administrative controls, and particularly their influence on human intrusion, the FEPs have been excluded, by regulation, from consideration in the human intrusion stylized analysis. On that basis, the consideration of the timing of occurrence of human intrusion without recognition (see Attachment III of this analysis report) is evaluated only on the physical properties of the drip shields and waste packages past 10,000 years, rather than on any consideration of administrative control, planning restrictions, repository markers, or an information repository. Although these institutional controls will be implemented, they do not influence the calculated timing or determination of the likelihood of a human intrusion, and, therefore, make no difference to determining the resulting dose to the RMEI or to the release of radionuclides to the accessible environment as addressed by the TSPA–LA model. ANL-WIS-MD-000019 REV 01 6-37 April 2004 TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Records and markers for repository (1.1.05.00.0A) Accidents and unplanned events during construction and operation (1.1.12.01.0A) Deliberate human intrusion (1.4.02.01.0A) Inadvertent human intrusion (1.4.02.02.0A) Unintrusive site investigation (1.4.03.00.0A) Drilling activities (human intrusion) (1.4.04.00.0A) Mining and other underground activities (1.4.05.00.0A) Altered soil or surface water chemistry (1.4.06.01.0A) Social and institutional developments (1.4.08.00.0A) Explosions and crashes (human activities) (1.4.11.00.0A) Wild and natural land and water use (2.4.08.00.0A) Agricultural land use and irrigation (2.4.09.01.0B) Urban and industrial land and water use (2.4.10.00.0A) Supplemental Discussion: Table 6-10. Indirect Inputs for Administrative Control of Repository Site (1.1.10.00.0A) Reference Input 10 CFR 63.51(a)(3)(i-iii) [DIRS 156605] Requirements for monuments and archives 10 CFR 63.72(a) and (b)(1-11) [DIRS 156671] Requirements for monuments and archives 10 CFR 63.121 [DIRS 156605] Requirements for land ownership and control 6.2.2.5 Monitoring of the Repository (1.1.11.00.0A) FEP Description: This FEP addresses the potential for monitoring that is carried out during or after operations, for either operational safety or verification of long-term performance, to detrimentally affect long-term performance. For instance, monitoring boreholes could provide enhanced pathways between the surface and the repository. Descriptor Phrases: Monitoring (performance confirmation) Screening Decision: Excluded – Low Consequence Screening Argument: “Monitoring of repository” is excluded from the TSPA–LA based on low consequence stemming from the regulatory requirements that monitoring activities must not adversely affect the ability of the repository to meet the performance objectives and requirements for seal confirmation. ANL-WIS-MD-000019 REV 01 6-38 April 2004 The repository will be constructed, operated, and closed according to NRC license requirements during the preclosure period. Modifications and/or deviations from the design are subject to regulatory requirements that address deliberate changes and modifications per 10 CFR 63.44 ([DIRS 156605]). Furthermore, at 10 CFR 63.73(a) ([DIRS 156605]), the NRC specifies prompt notification if there is a significant deficiency found in (1) the characteristics of the Yucca Mountain site, or (2) design and construction of the geologic repository area, including significant deviations from the design criteria and design bases stated in the application. Significant deviations that are detected during the operational period will be evaluated, and as needed, corrected. Any residual defects or fabrication or construction deficiencies, therefore, will be of a minor nature and will not lead to significant effects on the repository performance At 10 CFR Part 63 Subpart F ([DIRS 156605]), the regulation provides a list of requirements for a performance confirmation program to confirm design parameters and to ensure that the NRC is informed of changes needed in the design to accommodate actual field conditions. The performance confirmation plan documented in Snell et al. (2003 [DIRS 166219]) precludes significant effects from monitoring activities. A performance confirmation program is a regulatory requirement as specified at 10 CFR 63.131 ([DIRS 156605]). The provisions of that requirement include 10 CFR 63.131(c) ([DIRS 156605]) which states that the program must include in situ monitoring, field and laboratory testing, and in situ experiments, as may be appropriate to provide the data required by paragraph (a) of the section. Consequently, the use of in situ monitoring and experimentation is anticipated. However, the regulation also states that any monitoring program must be implemented so that it “does not adversely affect the ability of the geologic and engineered elements of the geologic repository to meet the performance objectives” per 10 CFR 63.131(d)(1) ([DIRS 156605]). All boreholes and monitoring wells will be drilled and sealed in accordance with regulatory requirements effective during the preclosure period. Confirmation that an adequate seal can be achieved is a regulatory requirement as specified at 10 CFR 63.133(d) [DIRS 156605]) which states that “tests must be conducted to evaluate the effectiveness of borehole, shaft, and ramp seals, before full scale operation proceeds to seal boreholes, shafts, and ramps.” Once properly sealed, there should be no pathway for unevaluated effect on groundwater flow systems, and boreholes should have no impact (i.e. are of low consequence) on the repository performance. Some qualitative understanding of the effect of any residual deficiencies can be taken from the multiple barrier analysis to be performed as part of the TSPA–LA modeling activities (BSC 2003, Section 8.3 [DIRS 166296]). This qualitative understanding can be supplemented with a quantitative measure provided by barrier neutralization analyses performed, as described in Appendix D.3 of Total System Performance Assessment-License Application Methods and Approach (BSC 2003 [DIRS 166296]). TSPA Disposition: Not Applicable Related Documents: None ANL-WIS-MD-000019 REV 01 6-39 April 2004 Related FEPs: Open site investigation boreholes (1.1.01.01.0A) Influx through holes drilled in drift wall or crown (1.1.01.01.0B) Drilling activities (human intrusion) (1.4.04.00.0A) Effects of drilling intrusion (1.4.04.01.0A) Supplemental Discussion: Table 6-11.Indirect Inputs for Monitoring of the Repository (1.1.11.00.0A) Reference Input 10 CFR 63.131 ([DIRS 156605] Requirement for performance confirmation 10 CFR 63.131(c) ([DIRS 156605] Requirement for in situ monitoring 10 CFR 63.131(d)(1) ([DIRS 156605] Requirement for no adverse effect from monitoring 10 CFR 63.133(d) [DIRS 156605] Requirement for seal testing BSC 2003, Section 8.3 [DIRS 166296] Multiple barrier analyses 6.2.2.6 Accidents and Unplanned Events during Construction and Operation (1.1.12.01.0A) FEP Description: The long-term performance of the disposal system might be seriously affected by unplanned or improper activities that take place during construction, operation, and closure of the repository Descriptor Phrases: Accidents (during construction and operation) Unplanned events (during construction and operation) Screening Decision: Excluded – Low Consequence Screening Argument: “Accidents and unplanned events during construction and operation” is excluded from the TSPA–LA based on low consequence because regulatory requirements for performance confirmation and quality assurance require evaluation of any such events should they occur. The history of the development of this FEP indicates that the intent and scope of the FEP is to include the effects of unplanned events during the “preclosure” phase that have longer lasting impact, such as improper operation, handling accidents, and some aspects of sabotage. The objective of the TSPA is to evaluate compliance with the “postclosure” performance objective. Events related to changes in the construction, operation, or closure schedule are outside the scope of the TSPA. Operations will be according to procedures acceptable to the NRC. At 10 CFR 63.73 ([DIRS 156605]), the NRC requires prompt notification if there is a significant deficiency found in the characteristics, design, and construction of the geologic repository operations area that, were it to remain uncorrected, could adversely affect safety at any time in the future. This ANL-WIS-MD-000019 REV 01 6-40 April 2004 includes significant deviations from the design criteria and design bases stated in the application, construction authorization, or the license. If the repository does not meet regulatory criteria, it will not be licensed, and waste will not be emplaced. Quality control procedures and performance confirmation are designed to detect operational events resulting in deviations from the repository design that might affect long-term performance. Any significant deviations would be detected during regulator audits and inspections per 10 CFR Part 63 Subpart D ([DIRS 156605]) and corrected before further work in the repository would be allowed to continue. Therefore, accidents and unplanned events during the operational phase would not have a significant effect on long-term performance and are excluded from the TSPA–LA based on low consequence. Sabotage is a form of deliberate human intrusion and has been excluded. It is more fully addressed in the FEPs 1.4.02.01.0A (deliberate human intrusion) and 1.4.11.00.0A (explosions and crashes (human activities)). Regardless of the type or cause of the event, some qualitative understanding of the potential effect of accidents and unplanned events can be taken from the multiple barrier analysis to be performed as part of the TSPA–LA modeling activities (BSC 2003, Section 8.3 [DIRS 166296]). This qualitative understanding can be supplemented with a quantitative measure provided by barrier neutralization analyses performed, as described in Appendix D.3 of Total System Performance Assessment-License Application Methods and Approach (BSC 2002 [DIRS 166296]). TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Site flooding (during construction and operation) (1.1.02.01.0A) Undesirable materials left (1.1.02.03.0A) Inadequate quality control and deviations from design (1.1.08.00.0A) Administrative control of repository site (1.1.10.00.0A) Retrievability (1.1.13.00.0A) Deliberate human intrusion (1.4.02.01.0A) Explosions and crashes (human activities) (1.4.11.00.0A) Mechanical impact on waste package (2.1.03.07.0A) Mechanical impact on drip shield (2.1.03.07.0B) Gas explosion in EBS (2.1.12.08.0A) Supplemental Discussion: Table 6-12. Indirect Inputs for Accidents and Unplanned Events during Construction and Operation (1.1.12.01.0A) Reference Input BSC 2003, Section 8.3 and Appendix D.3 [DIRS 166296] Multiple barrier analyses ANL-WIS-MD-000019 REV 01 6-41 April 2004 6.2.3 Human Intrusion Features, Events, and Processes This set of FEPs is related to the potential for human intrusion into the repository. Direct inputs used in this section originating from YMP-controlled sources or NRC regulations are listed in Section 4 and its subsections and no further discussion beyond that provided in Section 4 is required for such sources. Non-YMP sources of direct input are also cited in Section 4. Such sources and corroborating information are discussed in Attachment II of this analysis report. 6.2.3.1 Deliberate Human Intrusion (1.4.02.01.0A) FEP Description: Humans could deliberately intrude into the repository. Without appropriate precautions, intruders could experience high radiation exposures. Moreover, containment may be left damaged, which could increase radionuclide release rates to the biosphere. Motivation for deliberate human intrusion includes mining, waste retrieval, site remediation/improvement, archaeology, sabotage, and acts of war. Descriptor Phrases: Human intrusion (sabotage); Human intrusion (resource recovery); Human intrusion (acts of war). Screening Decision: Excluded – By Regulation Screening Argument: “Deliberate Human Intrusion” is excluded from the TSPA–LA human intrusion stylized analysis by regulation, which indicates that analysis of deliberate human intrusion and/or exposure of the intruders is not intended and does not serve the intended purpose of the analysis (10 CFR Part 63 Supplementary Information, 3.10 Human Intrusion Standard, p. 55761 66 FR 55732 [DIRS 156671]), and that exposure of the intruder is not to be considered (10 CFR 63.322(f) [DIRS 156605]). Human intrusion is defined at 10 CFR 63.302 ([DIRS 156605] and at 40 CFR 197.12 ([DIRS 165519])) as: Human intrusion means breaching any portion of the Yucca Mountain disposal system, within the repository footprint, by any human activity. This is an important concept in that “any” human activity that has the potential to breach the disposal system is included within the regulatory intent regarding human intrusion. In 10 CFR 63.2 ([DIRS 156605]), the term “performance assessment” is defined as an analysis that: Identifies the features, events, and processes (except human intrusion), and sequences of events and processes (except human intrusion), that might affect the ANL-WIS-MD-000019 REV 01 6-42 April 2004 Yucca Mountain disposal system and their probabilities of occurring during 10,000 years after disposal. From this statement stems a regulatory basis for excluding all FEPs that address human intrusion from consideration in the TSPA–LA model, although other regulations provide the conditions for which human intrusion must be considered. With regard to the motivation of a human intrusion being intentional/deliberate or inadvertent/accidental, the regulations at 10 CFR Part 63 ([DIRS 156605]) are silent. Similarly, the regulations at 40 CFR Part 197 ([DIRS 165519]) do not directly address the motivation or intentionality of the intrusion. However, the supplemental discussions for 40 CFR Part 197 [DIRS 155216] clarify that consideration of deliberate intrusion is not intended. In the preamble to 40 CFR Part 197 (66 FR 32074, Item 3 “What is the Standard for Human Intrusion?” p. 32105 [DIRS 155216]), the EPA, in response to comments regarding the human intrusion stylized analysis, states: Comments we received proposing alternative drilling frequencies and intentions, such as deliberately drilling into the repository, did not provide a sufficient rationale to abandon the NAS recommendations and we therefore retained our original framing for the scenario. The EPA amplifies this at 66 FR 32127 (66 FR 32074, p. 32127, more specifically Item 10. Is the Single–Borehole Scenario a Reasonable Approach to Judge the Resilience of the Yucca Mountain Disposal System Following Human Intrusion? [DIRS 155216]). The EPA explicitly states that: Some comments suggested that there is a strong possibility for deliberate intrusion into the repository to access its content as possible resources. We believe that there is no useful purpose to assessing the consequences of deliberate intrusions because in that case the intruders would be aware of the risks and consequences and would have decided to assume the risks. This is consistent with NAS’s conclusion regarding intentional intrusion (NAS Report, p. 14). Additionally the specifications at 10 CFR 63.322(f) ([DIRS 156605] and at 40 CFR 197.26(e) ([DIRS 165519])) indicating that only radionuclides transported to the saturated zone be considered, preclude the consideration of FEPs related to the exposure of the public, drillers, or other human intruders from cuttings, circulated materials, or tailings. The preamble to 10 CFR Part 63 (66 FR 55732, Supplementary Information, 3.10 Human Intrusion Standard, p. 55761 [DIRS 156671]) is clear with the intent of the NRC: Human intrusion has the potential for releasing particulate HLW to the surface with drill cuttings or providing a fast pathway for radionuclides to be transported to the SZ by water (e.g., water enters the waste package, releases radionuclides, and transports radionuclides by way of the borehole to the SZ). NAS concluded, and the Commission agrees, that analysis of the risk to the public or the intruders (i.e., drilling crew) from radioactive drill cuttings left unattended at the surface for subsequent dispersal into the biosphere would not fulfill the purpose of the human ANL-WIS-MD-000019 REV 01 6-43 April 2004 intrusion calculation because it would not show how well a particular repository site and design would protect the public at large. Rather, an analysis of the hazard of particulate HLW left on the surface would be dominated by assumptions subject to significant speculation and uncertainty regardless of the particular site or design under evaluation. Additionally, the release to the surface represents a one-time release with no long-term effect on the repository barriers. Consequently, all deliberate human intrusion FEPs are excluded based on the regulatory intent and all inadvertent intrusions are considered within the context of the regulatory requirements to consider only the human intrusion stylized analysis and the timing of such an event (see Attachment III of this analysis report). TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Records and markers for repository (1.1.05.00.0A) Administrative control of repository site (1.1.10.00.0A) Accidents and unplanned events during construction and operation (1.1.12.01.0A) Inadvertent human intrusion (1.4.02.02.0A) Unintrusive site investigation (1.4.03.00.0A) Drilling activities (human intrusion) (1.4.04.00.0A) Effects of drilling intrusion (1.4.04.01.0A) Mining and other underground activities (1.4.05.00.0A) Social and institutional developments (1.4.08.00.0A) Explosions and crashes (human activities) (1.4.11.00.0A) Urban and industrial land and water use (2.4.10.00.0A) Supplemental Discussion: Table 6-13. Indirect Inputs for Deliberate Human Intrusion (1.4.02.01.0A) Reference Input 10 CFR 63.302 ([DIRS 156605] Definition of human intrusion 40 CFR 197.12 ([DIRS 165519]) Definition of human intrusion 10 CFR 63.2 ([DIRS 156605]) Definition of performance assessment 10 CFR Part 63 ([DIRS 156605] NRC Regulations 40 CFR Part 197 [DIRS 165519] EPA Regulation 40 CFR Part 197 (66 FR 32074, Item 3 “What is the Standard for EPA intent to exclude human intrusion Human Intrusion?” p. 32105 [DIRS 155216] 66 FR 32127 (66 FR 32074, p. 32127, more specifically Item 10. EPA intent to exclude human intrusion Is the Single–Borehole Scenario a Reasonable Approach to Judge the Resilience of the Yucca Mountain Disposal System Following Human Intrusion? [DIRS 155216] 40 CFR 197.26(e) ([DIRS 165519] Only transport via groundwater to be considered EPA = U.S. Environmental Protection Agency, NRC = U.S. Nuclear Regulatory Commission ANL-WIS-MD-000019 REV 01 6-44 April 2004 6.2.3.2 Inadvertent Human Intrusion (1.4.02.02.0A) FEP Description: Humans could accidentally intrude into the repository. Without appropriate precautions, intruders could experience high radiation exposures. Moreover, containment may be left damaged, which could increase radionuclide release rates to the biosphere. Inadvertent human intrusion might occur during scientific, mineral or geothermal exploration. Descriptor Phrases: Human intrusion (drilling); Human intrusion (mining); Human intrusion (resource recovery). Screening Decision: Excluded – By Regulation Screening Argument: “Inadvertent Human Intrusion” is excluded from the TSPA–LA based on regulation (10 CFR 63.321 [DIRS 156605]) because inadvertent human intrusion without recognition by drillers prior to 10,000 years is not credible, and by regulatory intent, exposure to the intruders need not be considered With regard to the motivation of a human intrusion being intentional/deliberate or inadvertent/accidental, the regulations at 10 CFR Part 63 ([DIRS 156605]) are silent. Similarly, the regulations at 40 CFR Part 197 ([DIRS 165519]) do not directly address the motivation or intentionality of the intrusion. However, the supplemental discussions for 40 CFR Part 197 [DIRS 155216] clarify that consideration of deliberate intrusion is not intended. In the preamble to 40 CFR Part 197 (66 FR 32074, in a discussion regarding Item 3 “What is the Standard for Human Intrusion?” p. 32105 [DIRS 155216]), the EPA, in response to comments regarding the human intrusion stylized analysis, states: Comments we received proposing alternative drilling frequencies and intentions, such as deliberately drilling into the repository, did not provide a sufficient rationale to abandon the National Academy of Science (NAS) recommendations and we therefore retained our original framing for the scenario. The EPA amplifies this at 66 FR 32127 (66 FR 32074, p. 32127, more specifically Item 10. Is the Single–Borehole Scenario a Reasonable Approach to Judge the Resilience of the Yucca Mountain Disposal System Following Human Intrusion? [DIRS 155216]). The EPA explicitly states that: Some comments suggested that there is a strong possibility for deliberate intrusion into the repository to access its content as possible resources. We believe that there is no useful purpose to assessing the consequences of deliberate intrusions because in that case the intruders would be aware of the risks and consequences and would have decided to assume the risks. This is consistent with NAS’s conclusion regarding intentional intrusion (NAS Report, p. 14). ANL-WIS-MD-000019 REV 01 6-45 April 2004 Consequently, all deliberate human intrusion FEPs discussed in this analysis report are excluded based on the regulatory intent, and all inadvertent intrusions are considered within the context of the regulatory requirements to consider only human intrusion stylized analysis and the timing of such an event. At 10 CFR 63.321([DIRS 156605]), the NRC specifies the criteria under which human intrusion must be evaluated: DOE must determine the earliest time after disposal that the waste package would degrade sufficiently that a human intrusion could occur without recognition by the drillers. Furthermore, by way of explanation and corroboration, per 10 CFR 63.321(a) ([DIRS 156605]), DOE must: Provide the analyses and its technical bases used to determine the time of occurrence of human intrusion (see 10 CFR 63.322) without recognition by the drillers. And if complete waste package penetration is projected to occur before or at the 10,000-year performance period, then the DOE is to provide a demonstration (10 CFR 63.321(b)(1)) ([DIRS 156605]) that: …there is a reasonable expectation that the reasonably maximally exposed individual receives no more than an annual dose of 0.15 mSv (15 mrem) as a result of a human intrusion, at or before 10,000 years after disposal. And, per 10 CFR 63.321(b)(2) ([DIRS 156605]), If the exposure of the RMEI occurs after 10,000 years, or if the intrusion is projected to occur after 10,000 years, the results of the analysis and the bases of the analysis are to be provided in the environmental impact statement for Yucca Mountain. The drip shield and waste package barrier capability are based on the physical properties of the drip shield and waste packages. Degradation of these components with time is discussed in BSC 2003 (Section 6.7.1 [DIRS 161317]) and the analyses indicate that: • Because of the low corrosion rate of titanium alloy used for the drip shields, the initial breaches of the drip shields are not expected to occur until approximately 35,000 years and the median estimate of the mean time to initial breaching of drip shields is approximately 310,000 years; and • Because the corrosion rates of Alloy 22 (UNS N06022) used for the waste packages are so low, it is not expected that any waste packages would be breached by general corrosion or stress corrosion cracking during the first 10,000 years: models indicate that the time to initial breaching of the waste packages is on the order of 100,000 years. ANL-WIS-MD-000019 REV 01 6-46 April 2004 The results of the waste package degradations analyses cited from Calibrated Properties Model (BSC 2003, Section 6.7.1 [DIRS 161316]) result from the use of representative thermal hydrologic history files produced to allow model runs to be exercised in the cited report. The actual drip shield and waste package degradation profiles used in the TSPA-LA Model will make use of the actual thermal hydrologic history files appropriate for the repository. Because representative histories were used, however, significant differences in the degradation profile generated for TSPA-LA are not expected. While general corrosion occurs gradually over time up to the time of failure, the oxidation process is a surface phenomenon, and the underlying metal retains its integrity and resistance to drilling. Although results show the potential for failures at early time, these failures are the result of localized corrosion and, although modeled in TSPA-LA as a patch, are not associated with degradation of a significant surface area with respect to potential interaction with a rotary drill bit. See Attachment III of this analysis report for additional explanation. Regardless of these localized corrosion effects, the overall structural integrity of the waste package or drip shield, and the resistance to drilling is maintained. This is corroborated by the TSPA-SR drip shield and waste package studies, which indicate similarly long lifetimes for these components (CRWMS M&O 2000, Section 3.4 [DIRS 153246]) with the first drip shield failures occurring after about 20,000 years. The first failures of the waste package outer material, Alloy 22, by general corrosion occurred after approximately 30,000 years. Based on DOE analyses documented in Attachment III of this analysis report, the compressive strength and ductility of the metals from which the drip shields and waste package are fabricated differ significantly from the rock that would surround them and remain largely intact through the 10,000-year regulatory period. Drillers would notice these differences in properties based on the rate of penetration. Rate of penetration ranges from inversely proportional to the square of the compressive strength of the material being drilled, to inversely proportional, all other factors being equal (Bourgoyne et al. 1986, Eq. 5-19 [DIRS 155233]; Kahraman et al. 2000, Equation 8 [DIRS 167761]). As discussed in Attachment III, the compressive strength of the materials differ by a factor of two, suggesting that at a minimum, the rate of penetration would decrease by half or possibly to one fourth as the bit moved from the rock material to the engineered barrier, if in fact, the drill bit could even penetrate the engineered barrier. Other effects would also be noticeable. A full discussion is provided in Attachment III of this analysis report. The drillers, therefore, should recognize that they have attempted to drill into some material other than rock for at least as long as the drip shields or waste packages are intact. Based on these analyses, and in accordance with 10 CFR 63.321(b)(2) ([DIRS 156605]), dose analysis of the stylized human intrusion case is not required for TSPA-LA because the human intrusion without recognition cannot occur prior to 10,000 years. Because the dose from the human intrusion was expected to occur after the 10,000-year regulatory compliance period, the human intrusion dose analysis for TSPA-SR was previously presented in the FEIS (DOE 2002, Section 5.7.1 [DIRS 155970]). Documentation of the human intrusion stylized analysis for license application will include a description of the technical basis and analyses to support the determination of the time of occurrence of the human intrusion and an update to the human intrusion stylized analysis exposure determination. The requirements at 10 CFR 63.322(f) ([DIRS 156605] and at 40 CFR 197.26(e) ([DIRS 165519])), indicating that only radionuclides transported to the saturated zone be ANL-WIS-MD-000019 REV 01 6-47 April 2004 considered, preclude the consideration of FEPs related to the exposure of the public, drillers, or other human intruders from cuttings, circulated materials, or tailings. The preamble to 10 CFR Part 63 ((66 FR 55732) Supplementary information, 3.10 Human Intrusion Standard, p. 55761 [DIRS 156671]) is clear with the intent of the NRC: Human intrusion has the potential for releasing particulate HLW to the surface with drill cuttings or providing a fast pathway for radionuclides to be transported to the SZ by water (e.g., water enters the waste package, releases radionuclides, and transports radionuclides by way of the borehole to the SZ). NAS concluded, and the Commission agrees, that analysis of the risk to the public or the intruders (i.e., drilling crew) from radioactive drill cuttings left unattended at the surface for subsequent dispersal into the biosphere would not fulfill the purpose of the human intrusion calculation because it would not show how well a particular repository site and design would protect the public at large. Rather, an analysis of the hazard of particulate HLW left on the surface would be dominated by assumptions subject to significant speculation and uncertainty regardless of the particular site or design under evaluation. Additionally, the release to the surface represents a one-time release with no long-term effect on the repository barriers. Consequently, consideration of exposure to the intruders is specifically excluded. Therefore, consideration of inadvertent human intrusion is excluded from the TSPA–LA. Because the dose from the human intrusion is expected to occur after the 10,000-year regulatory compliance period, the human intrusion stylized analysis is not required for TSPA-LA. TSPA Disposition: Not Applicable Related Documents: Final Environmental Impact Statement for a Geologic Repository for the Disposal of Spent Nuclear Fuel and High-Level Radioactive Waste at Yucca Mountain, Nye County, Nevada DOE/EIS-0250 (DOE 2002 [DIRS 155970] Related FEPs: Records and markers for repository (1.1.05.00.0A) Administrative control of repository site (1.1.10.00.0A) Deliberate human intrusion (1.4.02.01.0A) Igneous Event Precedes Human Intrusion (1.4.02.03.0A) Seismic Event Precedes Human Intrusion (1.4.02.04.0A) Unintrusive site investigation (1.4.03.00.0A) Drilling activities (human intrusion) (1.4.04.00.0A) Effects of drilling intrusion (1.4.04.01.0A) Mining and other underground activities (1.4.05.00.0A) Social and institutional developments (1.4.08.00.0A) Explosions and crashes (human activity) (1.4.11.00.0A) Wild and natural land and water use (2.4.08.00.0A) Agricultural land use and irrigation (2.4.09.01.0B) Urban and industrial land and water use (2.4.10.00.0A) ANL-WIS-MD-000019 REV 01 6-48 April 2004 Supplemental Discussion: Table 6-14. Indirect Inputs for Inadvertent Human Intrusion (1.4.02.02.0A) Reference Input 10 CFR 63.321(a) [DIRS 156605] Requirement to provide evaluation of timing of intrusion 10 CFR Part 63 [DIRS 156605] NRC Regulations 40 CFR Part 197 [DIRS 165519] EPA Regulations 40 CFR Part 197 (66 FR 32074, in a discussion regarding Item 3 “What is the EPA intent to exclude deliberate Standard for Human Intrusion?” p. 32105 [DIRS 155216]) intrusion 66 FR 32127 (66 FR 32074, p. 32127, more specifically Item 10. Is the EPA intent to exclude deliberate Single–Borehole Scenario a Reasonable Approach to Judge the Resilience of intrusion the Yucca Mountain Disposal System Following Human Intrusion? [DIRS 155216]) 10 CFR 63.321(b)(1)) [DIRS 156605] Applicable if intrusion is prior to 10,000 years 10 CFR 63.321(b)(2) [DIRS 156605] Applicable if intrusion is after 10,000 years (CRWMS M&O 2000, Section 3.4 [DIRS 153246] TSPA-SR Waste package degradation results DOE 2002, Section 5.7.1 [DIRS 155970] TSPA-SR Human intrusion analysis results 40 CFR 197.26(e) [DIRS 165519]) Only transport through groundwater to be considered EPA = U.S. Environmental Protection Agency, NRC = U.S. Nuclear Regulatory Commission, TSPA = total system performance assessment for site recommendation 6.2.3.3 Igneous Event Precedes Human Intrusion (1.4.02.03.0A) FEP Description: An igneous event, such as a dike, intersects the repository and damages one or more waste packages. The damage is such that the material and structural properties of the drip shield and/or waste package are significantly altered. Because of the change in properties an intruder, using groundwater exploration drilling techniques, may not be able to recognize that something other than naturally-occurring materials have been encountered. Descriptor Phrases: Igneous event; Human intrusion event Screening Decision: Excluded – By Regulation Screening Argument: The probability of a dike intruding the repository has been determined to have a mean annualized probability of 1.7 x 10-8 (BSC 2003, Table 22 [DIRS 163769]), but in no estimates reviewed to date has the probability of igneous activity within the repository footprint been calculated to be as high as 1 x 10-5. Therefore, it is an unlikely event as defined in 10 CFR 63.342 ANL-WIS-MD-000019 REV 01 6-49 April 2004 ([DIRS 156605]), and need to be further considered in conjunction with human intrusion. In 10 CFR 63.342 ([DIRS 156605]), the NRC indicates that the unlikely FEPs (defined as those that are estimated to have less than one chance in 10 and at least one chance in 10,000 years of occurring within 10,000 years of disposal, or roughly an annualized probability of 1 x 10-5 to 1 x 10-8) are to be excluded from the assessments for the human intrusion and groundwater protection standards. Consequently, this particular FEP is excluded based on the regulation. Furthermore, the existing disruptive events scenario class allows for such an event to occur, but assumes that all waste packages within an intruded drift are damaged such that the drip shield and waste package provide no further protection. Thus, all waste packages in the intruded drift can contribute radionuclides to a groundwater release pathway, using the nominal scenario groundwater transport mechanism. Under the requirements of the human intrusion analysis, it is assumed that only one package is penetrated and that transport occurs to the saturated zone via the borehole. Because of the increased source term associated with the igneous intrusion, the existing disruptive scenario probability weighted exposure to the RMEI is likely conservative compared to the release from a single waste package release postulated for the human intrusion stylized analysis. Although, the release through the borehole may provide for a decreased transport time from the unsaturated to the saturated zone, the potential source term for the human intrusion stylized analysis is many times less than that associated with just the naturally occurring igneous event. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Igneous Intrusion Interacts with EBS Components (1.2.04.04.0A) Inadvertent human intrusion (1.4.02.02.0A) Effects of drilling intrusion (1.4.04.01.0A) Supplemental Discussion: There are no indirect inputs for this analysis. 6.2.3.4 Seismic Event Precedes Human Intrusion (1.4.02.04.0A) FEP Description: A seismic event occurs at the repository and damages one or more waste packages. The damage is such that the material and structural properties of the drip shield and/or waste package are significantly altered. Because of the change in properties an intruder, using groundwater exploration drilling techniques, may not be able to recognize that something other than naturally- occurring materials have been encountered. Descriptor Phrases: Seismic event, human intrusion event ANL-WIS-MD-000019 REV 01 6-50 April 2004 Screening Decision: Excluded – Low Consequence and By Regulation Screening Argument: The regulation requires that events with at least a 1 in 10 chance in 10,000 years of occurring (i.e. roughly an annualized of 1 x 10-5 or greater) be considered as part of the human intrusion assessment, but events with less of a chance not be considered (10 CFR 63.342 (DIRS 156605]). Seismic events with annualized probability between 1 x 10-4 to 1 x 10-5 are associated with the onset of seismic-related damage to the drip shield and waste package (BSC 2003, Sections 6.6.5, 6.3.2, 6.5.2 [DIRS 167780]). The onset of such events is associated with the damage of limited surface areas on the engineered barriers (such as initiation of cracking or development of corrosion sites). However, this does not necessarily indicate that the materials properties (such as compressive strength) of the material has been significantly altered or that structural strength of the barriers has altered significantly with respect to the potential for intrusion by drilling without recognition of the driller. As long as the materials retain their basic material characteristics (i.e. compressive strength in particular) the reaction of the drilling assembly will be such that a change in conditions will be recognized by a change in drilling conditions. As the damaged barrier is encountered, the drill bit will tend to “seize” or “catch” on any fractures or cracks in the surface, and the operation will produce “chatter” at the surface, or at the extreme, result in the drill bit being unable to rotate as it entangles with the metals and alloys of the engineered barriers. Under these conditions, the difference in shear strengths and modulus of elasticity will be the determining factors in being able to determine the difference between naturally-occurring materials and the engineered barrier materials. As further described in Attachment III of this analysis report, the difference in these particular properties for rock and the various metals and alloys used in the engineered barrier is significant. Based on information provided in Drift Degradation Analysis (BSC 2003 Tables V-5 through V-9 [DIRs 162711]) and MO0311RCKPRPCS.003 [DIRS 166073], the mean tensile strength and mean ultimate strength of the rock units are reported to range from 11.6 MPa to 23.8 MPa (or approximately 7 to 50 percent of the corresponding mean compressive strength). These rock tensile strengths are, at a minimum, a factor of 14 less than those of the engineered barrier materials. Even conservatively assuming an equivalence of the yield strength of a ductile material to tensile or ultimate strength of brittle material generates a difference of a factor of much greater than 2 (i.e., the threshold for recognition of a change in penetration rates, as explained in Attachment III of this analysis report). The material properties for the engineered barriers is taken from MO0003RIB00071.000 [DIRS 148850]; MO0003RIB00073.000 [DIRS 152926]; and MO0003RIB00076.000 [DIRS 153044]. The yield strength assigned to the engineered barrier materials is reported to range from 240 to 450 MPa for the stated offsets. A comparison of the ultimate and tensile strength to the rock units represents a minimum factor of 20 in material properties. Similarly, the mean modulus of elasticity for the rock materials is on the order of 6.9 to 33 GPa. Correspondingly, the reported shear modulus for the repository host horizon ranges from 0.42 to 8.21 GPa (or no greater than 1/3 of the maximum reported modulus of elasticity). By contrast, for the ductile alloys, the modulus of elasticity ranges from 106 to 206 GPa, representing a minimum factor of 3.2 different from the rock properties. ANL-WIS-MD-000019 REV 01 6-51 April 2004 Thus, the occurrence of a seismic events that must be considered (i.e. with annualized probabilities of 1 x 10-5 or greater) are of low consequence because they would not induce significant changes with the material properties of the host rock, or in the engineered barrier materials, and the penetration of such materials would still be recognizable. In 10 CFR 63.342 ([DIRS 156605]), the NRC indicates that the unlikely FEPs (defined as those that are estimated to have less than one chance in 10 and at least one chance in 10,000 of occurring within 10,000 years of disposal, or roughly an annualized probability of between 1 x 10-5 and 1 x 10-8) and very unlikely events (those with an annualized probability of less than 1 x 10-8) are to be excluded from the assessments for the human intrusion and groundwater protection standards. Consequently, other seismic events of greater magnitude, that may occur less frequently, but have the potential to result in increased damage, are excluded based on the regulatory proscription of considering such events. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Seismic Ground Motion Damages EBS Components (1.2.03.02.0A) Seismic-induced Rockfall Damages EBS Components (1.2.03.02.0B) Seismic-induced Drift Collapse Damages EBS Components (1.2.03.02.0C) Inadvertent human intrusion (1.4.02.02.0A) Effects of drilling intrusion (1.4.04.01.0A) Supplemental Discussion: There are no indirect inputs for this analysis. 6.2.3.5 Unintrusive Site Investigation (1.4.03.00.0A) FEP Description: This FEP addresses airborne, geophysical, or other surface-based investigations of a repository site after its closure. Descriptor Phrases: Human intrusion (archaeology); Human intrusion (surface activities). Screening Decision: Excluded – By Regulation Screening Argument: “Unintrusive site investigation” is excluded from the TSPA–LA based on regulatory definition and requirements for the human intrusion analysis and on low consequence of any unintrusive activities. By definition, unintrusive activities will have no discernible effect (i.e. are of low consequence) on the performance of the system. At 10 CFR 63.302 ([DIRS 156605] and at 40 CFR 197.12 ([DIRS 165519]), human intrusion is defined regulatorily as “…breaching of any portion of the Yucca Mountain disposal system, within the repository footprint, by any human activity.” ANL-WIS-MD-000019 REV 01 6-52 April 2004 Because it is unintrusive, there is no mechanism for the activities of this FEP to breach the disposal system or negatively impact the repository performance, and is therefore excludable by regulation and on low consequence. Alternately, any human activity (including surface-based site investigations) or human-induced activity that has a significant negative impact (breach) of the barrier system is, by definition, human intrusion. The regulations at 10 CFR 63.113(d) ([DIRS 156605] and at 40 CFR 197.26 ([DIRS 165519])) stipulate that human intrusion shall be considered only through the consideration of the human intrusion stylized analysis. Furthermore, the NRC, in the discussion regarding the timing and frequency of human intrusion (10 CFR Part 63, Preamble, 66 FR 55732, p. 55761 [DIRS 156671]), states that “some evaluations of the resource potential suggest that Yucca Mountain and the area around it does not represent an active candidate for either systematic or random exploratory drilling at this time.” A list of citations for those studies is available in the regulation. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Records and markers for repository (1.1.05.00.0A) Administrative control of repository site (1.1.10.00.0A) Deliberate human intrusion (1.4.02.01.0A) Inadvertent human intrusion (1.4.02.02.0A) Drilling activities (human intrusion) (1.4.04.00.0A) Effects of drilling intrusion (1.4.04.01.0A) Social and institutional developments (1.4.08.00.0A) Explosions and crashes (human activities) (1.4.11.00.0A) Wild and natural land and water use (2.4.08.00.0A) Agricultural land use and irrigation (2.4.09.01.0B) Urban and industrial land and water use (2.4.10.00.0A) Supplemental Discussion: Table 6-15. Indirect Inputs for Unintrusive Site Investigation (1.4.03.00.0A) Reference Input 40 CFR 197.12 [DIRS 165519] EPA definition of human intrusion 40 CFR 197.26 [DIRS 165519] EPA defined human intrusion analysis 10 CFR Part 63, Preamble, 66 FR 55732, p. 55761 NRC perspective on likelihood of mineral resources [DIRS 156671] EPA = U.S. Environmental Protection Agency, NRC = U.S. Nuclear Regulatory Agency ANL-WIS-MD-000019 REV 01 6-53 April 2004 6.2.3.6 Drilling Activities (Human Intrusion) (1.4.04.00.0A) FEP Description: This FEP addresses any type of drilling activity in the repository environment. These activities may be taken with or without awareness of the presence of the repository and with or without consent of the repository licensee. Drilling activities may be associated with natural resource exploration (water, oil and gas, minerals, geothermal energy), waste disposal (liquid), fluid storage (hydrocarbon, gas), or reopening existing boreholes. Descriptor Phrases: Human intrusion (drilling) Screening Decision: Excluded – By Regulation Screening Argument: “Drilling activities (human intrusion)” is excluded from the TSPA-LA based on regulation because consideration of only a stylized human intrusion is mandated in the regulations at 10 CFR 63.322 and 10 CFR 63.321 [DIRS 156605]). Human intrusion is defined at 10 CFR 63.302 ([DIRS 156605]) and 40 CFR 197.12 ([DIRS 165519]) as: Human intrusion means breaching any portion of the Yucca Mountain disposal system, within the repository footprint, by any human activity. This is an important concept in that “any” human activity that has the potential to breach the disposal system is included within the regulatory intent regarding human intrusion. In 10 CFR 63.2 ([DIRS 156605]), the term “performance assessment” is defined as an analysis that: Identifies the features, events, and processes (except human intrusion), and sequences of events and processes (except human intrusion), that might affect the Yucca Mountain disposal system and their probabilities of occurring during 10,000 years after disposal. From this statement stems a regulatory basis for excluding all FEPs that address human intrusion from consideration in the TSPA–LA model. However, there are specific regulatory provisions regarding consideration of human intrusion and drilling activities. To wit, 10 CFR 63.322 ([DIRS 156605]), states that: For the purposes of the analysis of human intrusion, DOE must make the following assumptions: (a) There is a single human intrusion as a result of exploratory drilling for ground water; ANL-WIS-MD-000019 REV 01 6-54 April 2004 (b) The intruders drill a borehole directly through a degraded waste package into the uppermost aquifer underlying the Yucca Mountain repository; (c) The drillers use the common techniques and practices that are currently employed in exploratory drilling for ground water in the region surrounding Yucca Mountain; (d) Careful sealing of the borehole does not occur, instead natural degradation processes gradually modify the borehole; (e) No particulate waste material falls into the borehole; (f) The exposure scenario includes only those radionuclides transported to the SZ by water (e.g., water enters the waste package, releases radionuclides, and transports radionuclides by way of the borehole to the SZ); and (g) No releases are included which are caused by unlikely natural processes and events. This is similar to the requirements in 40 CFR 197.26 ([DIRS 165519]), except that the EPA regulation does not specify item (e) above, and that item (f) is replaced with the following language at 40 CFR 197.26(e) ([DIRS 165519]): Only releases of radionuclides that occur as a result of the intrusion and that are transported through the resulting borehole to the SZ are projected; Several concepts in this set of regulations are important to the evaluation of human intrusion FEPs. First, rather than speculating on the nature and probability of future intrusion, the NRC has required that human intrusion be evaluated via a human intrusion stylized analysis. Secondly, the regulation specifies that the stylized analysis must assume the intrusion is the result of exploration for groundwater. This is emphasized in the regulations at 10 CFR 63.322 ([DIRS 156605]) with the statement that “DOE must make the following assumptions.” Therefore, all other types of drilling activities, by default, are excluded due to the regulatory-specified assumption. Additionally, the preamble to 10 CFR Part 63 ([DIRS 156605], Supplementary information, 3.10 Human Intrusion Standard, p. 55761) indicates that the NRC intended the analysis to be based on a stylized analysis. Accordingly, at 10 CFR 63.321 ([DIRS 156605]), the NRC specifies the criteria under which human intrusion must be evaluated: DOE must determine the earliest time after disposal that the waste package would degrade sufficiently that a human intrusion could occur without recognition by the drillers. ANL-WIS-MD-000019 REV 01 6-55 April 2004 Furthermore, by way of explanation and corroboration, per 10 CFR 63.321(a) ([DIRS 156605]), DOE must: Provide the analyses and its technical bases used to determine the time of occurrence of human intrusion (see 10 CFR 63.322) without recognition by the drillers. And if complete waste package penetration is projected to occur before or at the 10,000-year performance period, then the DOE is to provide a demonstration per 10 CFR 63.321(b)(1) ([DIRS 156605]) that: …there is a reasonable expectation that the reasonably maximally exposed individual receives no more than an annual dose of 0.15 mSv (15 mrem) as a result of a human intrusion, at or before 10,000 years after disposal. And, per 10 CFR 63.321(b)(2) ([DIRS 156605]): If the exposure of the RMEI occurs after 10,000 years, or if the intrusion is projected to occur after 10,000 years, the results of the analysis and the bases of the analysis are to be provided in the environmental impact statement for Yucca Mountain. The drip shield and waste package barrier capability are based on the physical properties of the drip shield and waste packages. Degradation of these components with time is discussed in BSC 2003 (Section 6.7.1 [DIRS 161317]), and the analyses indicate that: • Because of the low corrosion rate of titanium alloy used for the drip shields, the initial breaches of the drip shields are not expected to occur until will after 10,000 years; more specifically the modeling indicates approximately 35,000 years with the median estimate of the mean time to initial breaching of drip shields at approximately 310,000 years; and • Because the corrosion rates of Alloy 22 (UNS N06022) used for the waste packages are so low, it is not expected that any waste packages would be breached by general corrosion or stress corrosion cracking during the first 10,000 years: models indicate that the time to initial breaching of the waste packages is on the order of 100,000 years. The results of the waste package degradations analyses cited from Calibrated Properties Model (BSC 2003, Section 6.7.1 [DIRS 161316]) result from the use of representative thermal hydrologic history files produced to allow model runs to be exercised in the cited report. The actual drip shield and waste package degradation profiles used in the TSPA-LA Model will make use of the actual thermal hydrologic history files appropriate for the repository. Because representative histories were used, however, significant differences in the degradation profile generated for TSPA-LA are not expected. While general corrosion occurs gradually over time up to the time of failure, the oxidation process is a surface phenomenon, and the underlying metal retains its integrity and resistance to drilling. Although results show the potential for failures at early time, these failures are the result of localized corrosion and, although modeled in TSPA-LA as a patch, are not associated with degradation of a significant surface area with respect to potential interaction with a rotary drill bit. See Attachment III of this analysis report for additional explanation. Regardless of these localized corrosion effects, the overall structural ANL-WIS-MD-000019 REV 01 6-56 April 2004 integrity of the waste package or drip shield, and the resistance to drilling is maintained. This is corroborated by the TSPA-SR drip shield and waste package studies which indicate similarly long lifetimes for these components (CRWMS M&O 2000, Section 3.4 [DIRS 153246]) with the first drip shield failures occurring after about 20,000 years. The first failures of the waste package outer material, Alloy 22, by general corrosion occurred after approximately 30,000 years. Based on DOE analyses documented in Attachment III of this analysis report, the compressive strength and ductility of the metals from which the drip shields and waste package are fabricated differ significantly from the rock that would surround them and remain largely intact through the 10,000-year regulatory period. Drillers would notice these differences in properties based on the rate of penetration. Rate of penetration ranges from inversely proportional to the square of the compressive strength of the material being drilled, to inversely proportional, all other factors being equal (Bourgoyne et al. 1986, Eq. 5-19 [DIRS 155233]; Kahraman et al. 2000, Equation 8 [DIRS 167761]). As discussed in Attachment III, the compressive strength of the materials differ by a factor of two, suggesting the at a minimum, the rate of penetration would decrease by half or possibly to one fourth as the bit moved from the rock material to the engineered barrier, if in fact, the drill bit could even penetrate the engineered barrier. Other effects would also be noticeable. A full discussion is provided in Attachment III of this analysis report. The drillers, therefore, should recognize that they have attempted to drill into some material other than rock for at least as long as the drip shields or waste packages are intact. Based on these analyses, and in accordance with 10 CFR 63.321(b)(2) ([DIRS 156605]), dose analysis of the stylized human intrusion case is not required for TSPA-LA because the human intrusion without recognition cannot occur prior to 10,000 years. Because the dose from the human intrusion was expected to occur after the 10,000-year regulatory compliance period, the human intrusion dose analysis for TSPA-SR was previously presented in the FEIS (DOE 2002, Section 5.7.1 [DIRS 155970]). Documentation of the human intrusion stylized analysis for license application will include a description of the technical basis and analyses to support the determination of the time of occurrence of the human intrusion and an update to the human intrusion stylized analysis exposure determination. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Open site investigation boreholes (1.1.01.01.0A) Records and markers for repository (1.1.05.00.0A) Administrative control of repository site (1.1.10.00.0A) Monitoring of repository (1.1.11.00.0A) Deliberate human intrusion (1.4.02.01.0A) Inadvertent human intrusion (1.4.02.02.0A) Unintrusive site investigation (1.4.03.00.0A) Effects of drilling intrusion (1.4.04.01.0A) Mining and other underground activities (1.4.05.00.0A) ANL-WIS-MD-000019 REV 01 6-57 April 2004 Social and institutional developments (1.4.08.00.0A) Urban and industrial land and water use (2.4.10.00.0A) Supplemental Discussion: Table 6-16. Indirect Inputs for Drilling Activities (Human Intrusion) (1.4.04.00.0A) Reference Input 10 CFR 63.302 [DIRS 156605] NRC definition of human intrusion 40 CFR 197.12 [DIRS 165519] NRC definition of human intrusion 10 CFR 63.2 [DIRS 156605] NRC definition of performance assessment 40 CFR 197.26 [DIRS 165519] EPA defined human intrusion analysis 40 CFR 197.26(e) [DIRS 165519] Only groundwater transport need be considered 10 CFR Part 63 [DIRS 156605] NRC Regulations 10 CFR 63.321(a) [DIRS 156605] Requirement to provide evaluation of timing of intrusion 10 CFR 63.321(b)(1) [DIRS 156605] Applicable f intrusion is prior to 10,000 years 10 CFR 63.321(b)(2) [DIRS 156605] Applicable if intrusion is after 10,000 years CRWMS M&O 2000, Section 3.4 [DIRS 153246] TSPA-SR Waste package degradation results DOE 2002, Section 5.7.1 [DIRS 155970] TSPA-SR human intrusion analysis results EPA = U.S. Environmental Protection Agency, NRC = U.S. Nuclear Regulatory Commission, TSPA-SR = total system performance assessment for site recommendation 6.2.3.7 Effects of Drilling Intrusion (1.4.04.01.0A) FEP Description: Drilling activities that intrude into the repository may create new release pathways to the biosphere and alter existing pathways. Possible effects of a drilling intrusion include interaction with waste packages, increased saturation in repository leading to enhanced transport to the saturated zone, changes to groundwater and EBS chemistry, and waste brought to surface. Descriptor Phrases: Human intrusion (drilling) Screening Decision: Excluded – By Regulation Screening Argument: “Effects of Drilling Intrusion” is excluded from the TSPA–LA based on regulation because consideration of only a stylized human intrusion is mandated by the regulations at 10 CFR 63.322 and 10 CFR 63.321([DIRS 156605]) Human intrusion is defined at 10 CFR 63.302 ([DIRS 156605]) and at 40 CFR 197.12 ([DIRS 165519])) as: Human intrusion means breaching any portion of the Yucca Mountain disposal system, within the repository footprint, by any human activity. This is an important concept in that any human activity that has the potential to breach the disposal system is included within the regulatory intent regarding human intrusion. ANL-WIS-MD-000019 REV 01 6-58 April 2004 In 10 CFR 63.2 ([DIRS 156605]), the term performance assessment is defined as an analysis that: Identifies the features, events, and processes (except human intrusion), and sequences of events and processes (except human intrusion), that might affect the Yucca Mountain disposal system and their probabilities of occurring during 10,000 years after disposal. From this statement stems a regulatory basis for excluding all FEPs that address human intrusion from consideration in the TSPA–LA model. However, there are specific regulatory provisions regarding consideration of human intrusion. To wit; 10 CFR 63.322 ([DIRS 156671]), states that: For the purposes of the analysis of human intrusion, DOE must make the following assumptions: (a) There is a single human intrusion as a result of exploratory drilling for ground water; (b) The intruders drill a borehole directly through a degraded waste package into the uppermost aquifer underlying the Yucca Mountain repository; (c) The drillers use the common techniques and practices that are currently employed in exploratory drilling for ground water in the region surrounding Yucca Mountain; (d) Careful sealing of the borehole does not occur, instead natural degradation processes gradually modify the borehole; (e) No particulate waste material falls into the borehole; (f) The exposure scenario includes only those radionuclides transported to the SZ by water (e.g., water enters the waste package, releases radionuclides, and transports radionuclides by way of the borehole to the SZ); and (g) No releases are included which are caused by unlikely natural processes and events. This is similar to the requirements in 40 CFR 197.26 ([DIRS 165519]), except that the EPA regulation does not specify item (e) above, and that item (f) is replaced with the following language at 40 CFR 197.26(e) ([DIRS 165519]). Only releases of radionuclides that occur as a result of the intrusion and that are transported through the resulting borehole to the SZ are projected; Several concepts in this set of regulations are important to the evaluation of human intrusion FEPs. First, rather than speculating on the nature and probability of future intrusion, the NRC ANL-WIS-MD-000019 REV 01 6-59 April 2004 has required that human intrusion be evaluated via a human intrusion stylized analysis. Secondly, the regulation indicates that the stylized analysis be based on the assumption of release through the borehole, and not through other alternate pathways such as cuttings brought to the surface. This is emphasized in the regulation at 10 CFR 63.322 (66 FR 55732 [DIRS 156671]) with the statement that “DOE must make the following assumption.” Additionally, the preamble to 10 CFR Part 63 (66 FR 55732 [DIRS 156671], Supplementary Information, 3.10 Human Intrusion Standard, p. 55761) indicates that the NRC intended the analysis to be based on a stylized analysis. Accordingly, at 10 CFR 63.321 ([DIRS 156605]), the NRC specifies the criteria under which human intrusion must be evaluated: DOE must determine the earliest time after disposal that the waste package would degrade sufficiently that a human intrusion could occur without recognition by the drillers. Furthermore, by way of exploration and corroboration, per 10 CFR 63.321(a) ([DIRS 156605]), DOE must: Provide the analyses and its technical bases used to determine the time of occurrence of human intrusion (see 63.322) without recognition by the drillers. And if complete waste package penetration is projected to occur before or at the 10,000-year performance period, then the DOE is to provide a demonstration per 10 CFR 63.321(b)(1) ([DIRS 156605]) that: …there is a reasonable expectation that the reasonably maximally exposed individual receives no more than an annual dose of 0.15 mSv (15 mrem) as a result of a human intrusion, at or before 10,000 years after disposal. And, per 10 CFR 63.321(b)(2) ([DIRS 156605]): If the exposure of the RMEI occurs after 10,000 years, or if the intrusion is projected to occur after 10,000 years, the results of the analysis and the bases of the analysis are to be provided in the environmental impact statement for Yucca Mountain. Additionally, the requirements at 10 CFR 63.322(f) ([DIRS 156605] and at 40 CFR 197.26(e) ([DIRS 165519])), indicating that only radionuclides transported to the saturated zone be considered, preclude the consideration of FEPs related to the exposure of the public, drillers, or other human intruders from cuttings, circulated materials, or tailings. The preamble to 10 CFR Part 63 (66 FR 55732, Supplementary Information, 3.10 Human Intrusion Standard, p. 55761 [DIRS 156671]) is clear with the intent of the NRC: Human intrusion has the potential for releasing particulate HLW to the surface with drill cuttings or providing a fast pathway for radionuclides to be transported to the SZ by water (e.g., water enters the waste package, releases radionuclides, and transports radionuclides by way of the borehole to the SZ). The NAS concluded, and the Commission agrees, that analysis of the risk to the public or ANL-WIS-MD-000019 REV 01 6-60 April 2004 the intruders (i.e., drilling crew) from radioactive drill cuttings left unattended at the surface for subsequent dispersal into the biosphere would not fulfill the purpose of the human intrusion calculation because it would not show how well a particular repository site and design would protect the public at large. Rather, an analysis of the hazard of particulate HLW left on the surface would be dominated by assumptions subject to significant speculation and uncertainty regardless of the particular site or design under evaluation. Additionally, the release to the surface represents a one-time release with no long-term effect on the repository barriers. The drip shield and waste package barrier capability are based on the physical properties of the drip shield and waste packages. Degradation of these components with time is discussed in BSC 2003 (Section 6.7.1 [DIRS 161317]), and the analysis indicates that: • Because of the low corrosion rate of titanium alloy used for the drip shields, the initial breaches of the drip shields are not expected to occur until approximately 35,000 years and the median estimate of the mean time to initial breaching of drip shields is approximately 310,000 years; and • Because the corrosion rates of Alloy 22 (UNS N06022) used for the waste packages are so low, it is not expected that any waste packages would be breached by general corrosion or stress corrosion cracking during the first 10,000 years: models indicate that the time to initial breaching of the waste packages is on the order of 100,000 years The results of the waste package degradations analyses cited from BSC 2003 (Section 6.7.1 [DIRS 161316]) result from the use of representative thermal hydrologic history files produced to allow model runs to be exercised in the cited report. The actual drip shield and waste package degradation profiles used in the TSPA-LA Model will make use of the actual thermal hydrologic history files appropriate for the repository. Because representative histories were used, however, significant differences in the degradation profile generated for TSPA-LA are not expected. While general corrosion occurs gradually over time up to the time of failure, the oxidation process is a surface phenomenon, and the underlying metal retains its integrity and resistance to drilling. Although results show the potential for failures at early time, these failures are the result of localized corrosion and, although modeled in TSPA-LA as a patch, are not associated with degradation of a significant surface area with respect to potential interaction with a rotary drill bit. See Attachment III of this analysis report for additional explanation. Regardless of these localized corrosion effects, the overall structural integrity of the waste package or drip shield, and the resistance to drilling is maintained. This is corroborated by the TSPA-SR drip shield and waste package studies which indicate similarly long lifetimes for these components (CRWMS M&O 2000, Section 3.4 [DIRS 153246]) with the first drip shield failures occurring after about 20,000 years. The first failures of the waste package outer material, Alloy 22, by general corrosion occurred after approximately 30,000 years (this general corrosion duration did not consider the 5 cm of stainless steel beneath the Alloy 22). Based on DOE analyses documented in Attachment III of this analysis report, the compressive strength and ductility of the metals from which the drip shields and waste package are fabricated differ significantly from the rock that would surround them and remain largely intact through the 10,000-year regulatory period. Drillers would notice these differences in properties based on the ANL-WIS-MD-000019 REV 01 6-61 April 2004 rate of penetration. Rate of penetration ranges from inversely proportional to the square of the compressive strength of the material being drilled, to inversely proportional, all other factors being equal (Bourgoyne et al. 1986, Eq. 5-19 [DIRS 155233]; Kahraman et al. 2000, Equation 8 [DIRS 167761]). As discussed in Attachment III, the compressive strength of the materials differ by a factor of two, suggesting the at a minimum, the rate of penetration would decrease by half or possibly to one fourth as the bit moved from the rock material to the engineered barrier, if in fact, the drill bit could even penetrate the engineered barrier. Other effects would also be noticeable. A full discussion is provided in Attachment III of this analysis report. The drillers, therefore, should recognize that they have attempted to drill into some material other than rock for at least as long as the drip shields or waste packages are intact. Based on these analysis, and in accordance with 10 CFR 63.321(b)(2) (DIRS 156605]), dose analysis of the stylized human intrusion case is not required for TSPA-LA because the human intrusion without recognition cannot occur prior to 10,000 years. Because the dose from the human intrusion was expected to occur after the 10,000-year regulatory compliance period, the human intrusion dose analysis for TSPA-SR was previously presented in the FEIS (DOE 2002, Section 5.7.1 [DIRS 155970]). Documentation of the human intrusion stylized analysis for license application will include a description of the technical basis and analyses to support the determination of the time of occurrence of the human intrusion and an update to the human intrusion stylized analysis exposure determination. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Open site investigation boreholes (1.1.01.01.0A) Influx through holes drilled in drift wall or crown (1.1.01.01.0B) Monitoring of repository (1.1.11.00.0A) Deliberate human intrusion (1.4.02.01.0A) Inadvertent human intrusion (1.4.02.02.0A) Igneous Event Precedes Human Intrusion (1.4.02.03.0A) Seismic Event Precedes Human Intrusion (1.4.02.04.0A) Unintrusive site investigation (1.4.03.00.0A) Mining and other underground activities (1.4.05.00.0A) Drilling activities (human intrusion) (1.4.04.00.0A) Geochemical interactions and evolution in the SZ (2.2.08.03.0A) Geochemical interactions and evolution in the UZ (2.2.08.03.0B) ANL-WIS-MD-000019 REV 01 6-62 April 2004 Supplemental Discussion: Table 6-17. Indirect Inputs for Effects of Drilling Intrusion (1.4.04.01.0A) Reference Input 10 CFR 63.302 [DIRS 156605] NRC definition of human intrusion 40 CFR 197.12 [DIRS 165519]) EPA definition of human intrusion 10 CFR 63.2 [DIRS 156605] NRC definition of performance assessment 40 CFR 197.26 [DIRS 165519] EPA defined human intrusion analysis 40 CFR 197.26(e) [DIRS 165519] Only groundwater transport needs to be considered 10 CFR Part 63 [DIRS 156605]) NRC Regulations 10 CFR 63.321(a) [DIRS 156605] Requirement to provide evaluation of timing of intrusion 10 CFR 63.321(b)(1) [DIRS 156605] Applicable if intrusion is prior to 10,000 years 10 CFR 63.321(b)(2) [DIRS 156605] Applicable if intrusion is after 10,000 years 40 CFR 197.26(e) [DIRS 165519] Only groundwater transport needs to be considered CRWMS M&O 2000, Section 3.4 [DIRS 153246] TSPA-SR waste package degradation results FEIS (DOE 2002, Section 5.7.1 [DIRS 155970] TSPA-SR human intrusion analysis results EPA = U.S. Environmental Protection Agency, NRC = U.S. Nuclear Regulatory Commission, TSPA-SR = total system performance assessment 6.2.3.8 Mining and Other Underground Activities (Human Intrusion) (1.4.05.00.0A) FEP Description: Mining and other underground human activities (e.g., tunneling, underground construction, quarrying) could disrupt the disposal system. Descriptor Phrases: Human intrusion (mining); Human intrusion (quarrying); Human intrusion (excavation); Human intrusion (resource recovery). Screening Decision: Excluded – By Regulation Screening Argument: “Mining and other underground activities (human intrusion)” is excluded from the TSPA–LA and the human-intrusion stylized analysis based on regulation because consideration of only a stylized human intrusion is mandated at 10 CFR 63.322 ([DIRS 156605]). Human intrusion is defined at 10 CFR 63.302 ([DIRS 156605] and at 40 CFR 197.12 ([DIRS 165519]) as: Human intrusion means breaching any portion of the Yucca Mountain disposal system, within the repository footprint, by any human activity. This is an important concept in that any human activity that has the potential to breach the disposal system is included within the regulatory intent regarding human intrusion. ANL-WIS-MD-000019 REV 01 6-63 April 2004 At 10 CFR 63.2 ([DIRS 156605]), the term performance assessment is defined as an analysis that: Identifies the features, events, and processes (except human intrusion), and sequences of events and processes (except human intrusion), that might affect the Yucca Mountain disposal system and their probabilities of occurring during 10,000 years after disposal. From this statement stems a regulatory basis for excluding all FEPs that address human intrusion from consideration in the TSPA–LA model. However, there are specific regulatory provisions regarding consideration of human intrusion. To wit; 10 CFR 63.322 (66 FR 55732 [DIRS 156671]), states that: For the purposes of the analysis of human intrusion, DOE must make the following assumptions: (a) There is a single human intrusion as a result of exploratory drilling for groundwater; (b) The intruders drill a borehole directly through a degraded waste package into the uppermost aquifer underlying the Yucca Mountain repository; (c) The drillers use the common techniques and practices that are currently employed in exploratory drilling for ground water in the region surrounding Yucca Mountain; (d) Careful sealing of the borehole does not occur, instead natural degradation processes gradually modify the borehole; No particulate waste material falls into the borehole; (f) The exposure scenario includes only those radionuclides transported to the SZ by water (e.g., water enters the waste package, releases radionuclides, and transports radionuclides by way of the borehole to the SZ); and (g) No releases are included which are caused by unlikely natural processes and events. This is similar to the requirements in 40 CFR 197.26 ([DIRS 165519]), except that the EPA regulation does not specify item (e) above, and that item (f) is replaced with the following language at 40 CFR 197.26(e) ([DIRS 165519]): Only releases of radionuclides that occur as a result of the intrusion and that are transported through the resulting borehole to the SZ are projected. Several concepts in this set of regulations are important to the evaluation of human intrusion FEPs. First, rather than speculating on the nature and probability of future intrusion, the NRC has required that human intrusion be evaluated via a human intrusion stylized analysis. ANL-WIS-MD-000019 REV 01 6-64 April 2004 Secondly, the regulation specifies that the stylized analysis assume the intrusion is the result of exploration for groundwater. This is emphasized in the regulations at 10 CFR 63.322 ([DIRS 156605]) with the statement that “DOE must make the following assumptions.” Therefore, all other types of intrusion, including mining, by default, are excluded due to the regulatory-specified assumption. With regard to the motivation of a human intrusion being intentional/deliberate or inadvertent/accidental, the regulations at 10 CFR Part 63 ([DIRS 156605]) are silent. Similarly, the regulations at 40 CFR Part 197 ([DIRS 165519]) do not directly address the motivation or intentionality of the intrusion. However, the supplemental discussions for 40 CFR Part 197 clarify that consideration of deliberate intrusion is not intended. In the preamble to 40 CFR Part 197 (66 FR 32074, Item 3 “What is the Standard for Human Intrusion?” p. 32105 [DIRS 155216]), the EPA, in response to comments regarding the human intrusion stylized analysis, states: Comments we received proposing alternative drilling frequencies and intentions, such as deliberately drilling into the repository, did not provide a sufficient rationale to abandon the NAS recommendations and we therefore retained our original framing for the scenario. The EPA amplifies this (66 FR 32074, p. 32127, more specifically Item 10. Is the Single-Borehole Scenario a Reasonable Approach to Judge the Resilience of the Yucca Mountain Disposal System Following Human Intrusion? [DIRS 155216]). The EPA explicitly states that: Some comments suggested that there is a strong possibility for deliberate intrusion into the repository to access its content as possible resources. We believe that there is no useful purpose to assessing the consequences of deliberate intrusions because in that case the intruders would be aware of the risks and consequences and would have decided to assume the risks. This is consistent with NAS’s conclusion regarding intentional intrusion (NAS Report, p. 14). Additionally, the requirements at 10 CFR 63.322(f) ([DIRS 156605] and at 40 CFR 197.26(e) ([DIRS 165519])), indicating that only radionuclides transported to the saturated zone be considered, preclude the consideration of FEPs related to the exposure of the public, drillers, or other human intruders from cuttings, circulated materials, or tailings. The preamble to 10 CFR Part 63 (66 FR 55732, Supplementary Information, 3.10 Human Intrusion Standard, p. 55761 [DIRS 156671]) is clear with the intent of the NRC: Human intrusion has the potential for releasing particulate HLW to the surface with drill cuttings or providing a fast pathway for radionuclides to be transported to the SZ by water (e.g., water enters the waste package, releases radionuclides, and transports radionuclides by way of the borehole to the SZ). NAS concluded, and the Commission agrees, that analysis of the risk to the public or the intruders (i.e., drilling crew) from radioactive drill cuttings left unattended at the surface for subsequent dispersal into the biosphere would not fulfill the purpose of the human intrusion calculation because it would not show how well a particular repository ANL-WIS-MD-000019 REV 01 6-65 April 2004 site and design would protect the public at large. Rather, an analysis of the hazard of particulate HLW left on the surface would be dominated by assumptions subject to significant speculation and uncertainty regardless of the particular site or design under evaluation. Additionally, the release to the surface represents a one-time release with no long-term effect on the repository barriers. Consequently, all deliberate human intrusion FEPs discussed in this analysis report are excluded based on the regulatory intent, and all inadvertent intrusions are considered within the context of the regulatory requirements to consider only the stylized human intrusion and the timing of such an event. (See also Assumption 5.2 of this analysis report regarding the loss of records and ineffectiveness of repository markers). TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Records and markers for repository (1.1.05.00.0A) Administrative control of repository site (1.1.10.00.0A) Deliberate human intrusion (1.4.02.01.0A) Inadvertent human intrusion (1.4.02.02.0A) Drilling activities (human intrusion) (1.4.04.00.0A) Effects of drilling intrusion (1.4.04.01.0A) Repository excavation (1.4.05.00.0A) Altered soil or surface water chemistry (1.4.06.01.0A) Social and institutional developments (1.4.08.00.0A) Urban and industrial land and water use (2.4.10.00.0A) Supplemental Discussion: Table 6-18. Indirect Inputs for Mining and Other Underground Activities (Human Intrusion) (1.4.05.00.0A) Reference Input 10 CFR 63.302 [DIRS 156605] NRC definition of human intrusion 40 CFR 197.12 [DIRS 165519] EPA definition of human intrusion 10 CFR 63.2 [DIRS 156605]) NRC definition of performance assessment 40 CFR 197.26 [DIRS 165519] EPA defined human intrusion analysis 40 CFR 197.26(e) [DIRS 165519] Only groundwater transport needs to be considered 10 CFR Part 63 [DIRS 156605] NRC Regulations 40 CFR Part 197 [DIRS 165519] EPA Regulations 40 CFR Part 197 (66 FR 32074, Item 3 “What is the Standard EPA intent to exclude human intrusion for Human Intrusion?” p. 32105 [DIRS 155216]) 66 FR 32074, p. 32127, more specifically Item 10. Is the EPA intent to exclude human intrusion Single –Borehole Scenario a Reasonable Approach to Judge the Resilience of the Yucca Mountain Disposal System Following Human Intrusion? [DIRS 155216] EPA = U.S. Environmental Protection Agency, NRC = U.S. Nuclear Regulatory Commission ANL-WIS-MD-000019 REV 01 6-66 April 2004 6.2.3.9 Explosions and Crashes (Human Activities) (1.4.11.00.0A) FEP Description: Explosions or crashes resulting from future human activities may affect the long-term performance of the repository. Explosions may result from nuclear war, underground nuclear testing or resource exploitation. Descriptor Phrases: Human intrusion (explosion); Human intrusion (crashes); Human intrusion (acts of war); Human intrusion (sabotage). Screening Decision: Excluded – By Regulation and Low Consequence Screening Argument: “Explosions and Crashes (Human Activities)” is excluded from the TSPA–LA based on regulation and low consequence because the type of phenomena listed would primarily have only surficial effects, unless the repository was deliberately targeted, which is a specific form of deliberate human intrusion as is therefore excluded (10 CFR 63.322 ([DIRS 156605]). Resource exploration, in the form of groundwater exploitation, is addressed as part of the human intrusion stylized analysis. The development history for this FEP indicates that several possible cases are covered by this FEP. These include surface detonation of nuclear or conventional weapons, aircraft crashes, subsurface explosion related to resource recovery, and nuclear detonation nearby in the subsurface. Human intrusion is defined at 10 CFR 63.302 ([DIRS 156605] and at 40 CFR 197.12 ([DIRS 165519]) as: Human intrusion means breaching any portion of the Yucca Mountain disposal system, within the repository footprint, by any human activity This is an important concept in that any human activity that has the potential to breach the disposal system is included within the regulatory intent regarding human intrusion. In 10 CFR 63.2 ([DIRS 156605]), the term performance assessment is defined as an analysis that: Identifies the features, events, and processes (except human intrusion), and sequences of events and processes (except human intrusion), that might affect the Yucca Mountain disposal system and their probabilities of occurring during 10,000 years after disposal. From this statement stems a regulatory basis for excluding all FEPs that address human intrusion, including explosions and crashes, from consideration in the TSPA–LA model. However, there are specific regulatory provisions regarding consideration of human intrusion as ANL-WIS-MD-000019 REV 01 6-67 April 2004 a stylized analysis based on exploratory drilling for groundwater (10 CFR 63.322) ([DIRS 156605]). With regard to the motivation of a human intrusion being intentional/deliberate or inadvertent/accidental, the regulations at 10 CFR Part 63 ([DIRS 156605]) are silent. Similarly, the regulations at 40 CFR Part 197 ([DIRS 165519]) do not directly address the motivation or intentionality of the intrusion. However, the supplemental discussions for 40 CFR Part 197 clarify that consideration of deliberate intrusion is not intended. In the preamble to 40 CFR Part 197 (66 FR 32074, Item 3 “What is the Standard for Human Intrusion?” p. 32105 [DIRS 155216]), the EPA, in response to comments regarding the human intrusion stylized analysis, states: Comments we received proposing alternative drilling frequencies and intentions, such as deliberately drilling into the repository, did not provide a sufficient rationale to abandon the NAS recommendations and we therefore retained our original framing for the scenario. The EPA amplifies this at 66 FR 32127 (66 FR 32074, p. 32127, more specifically Item 10. Is the Single–Borehole Scenario a Reasonable Approach to Judge the Resilience of the Yucca Mountain Disposal System Following Human Intrusion? [DIRS 155216]). The EPA explicitly states that: Some comments suggested that there is a strong possibility for deliberate intrusion into the repository to access its content as possible resources. We believe that there is no useful purpose to assessing the consequences of deliberate intrusions because in that case the intruders would be aware of the risks and consequences and would have decided to assume the risks. This is consistent with NAS’s conclusion regarding intentional intrusion (NAS Report, p. 14). Consequently, all deliberate human intrusion FEPs discussed in this analysis report are excluded based on the regulatory intent, and all inadvertent intrusions are considered within the context of the regulatory requirements to consider only the human intrusion stylized analysis and the timing of such an event. With regard to explosions and crashes, the depth of the repository suggests that such events are of low consequence to repository performance. The minimum depth of the TSPA-LA repository (distance from the emplacement area to the overlying surface) is approximately 200 m. Drawing 800-IED-WIS0-00101-000-00A (BSC 2004 [DIRS 164519] indicates that the overburden thickness from emplacement area to topographic surface is 215 m. A depth of 200 m will be used in the calculation to provide a small margin of conservatism. With regard to potential consequences of airplane crashes, or surface and subsurface detonation, the results of the evaluation of meteorite impact cratering described in Attachment III of this analysis report are relevant, and direct input to the discussion are addressed in Attachment II. To be of consequence, the detonation or impact must either be sufficient to exhume the waste, create fracturing to depth, or create a significant increase in fracturing over a widespread area such that infiltration patterns and rates are significantly altered. The analysis presented in Attachment IV ANL-WIS-MD-000019 REV 01 6-68 April 2004 suggests that impacts resulting in craters with diameters on the scale of 80 to 100 m (262 to 328 feet) might be sufficient to lead to fracturing of the geologic units overlying the repository sufficient to increase infiltration. A crater with a diameter on the order of 300 m (984 feet) is needed to initiate fracturing to the depth of the repository, and a crater with a diameter on the order of 1 km (3,280 feet) is needed to exhume waste directly to the surface. Based on Dence et al. (1977, Figure 12 [DIRS 135253], such crater diameters, respectively, are associated with energy release on the scale of 1012 to 1017 joules (200 tons to 20 megatons (Mt) TNT equivalent based on a relationship of 1 megaton (Mt) TNT = 4.2 × 1015 joules (J) per Chapman and Morrison (1994, p. 33 [DIRS 135245]). Such large-scale energy releases are not associated with surface impact of an aircraft or surface detonation of conventional ordnance because of insufficient energy release to the subsurface. By way of comparison, Stix and Yam (2001, p. 15 [DIRS 160994]) suggest that kinetic energy of a Boeing 767 is on the order of 1 to 2 tons TNT. Stix and Yam also indicate that the potential explosive energy release from fuel on board a large jet passenger aircraft is on the order of 180 tons TNT, though this would not all be focused into the subsurface. With regard to more conventional ordinance, Ferguson (2002 [DIRS 150988]) suggests that the conventional yield of a GBU-28 “bunker buster” bomb is on the order of 2 tons. With regard to earth-penetrating weapons, available direct inputs suggest that a penetration depth of 30 m is a reasonable maximum estimate. Backman and Goldstein (1978, pp. 32 and 38 [DIRS 167628]) provide two direct inputs. For a 5000-psi concrete (34.5 MPa), which is at the lower end of the range in rock compressive strengths at Yucca Mountain, the maximum penetration depth is given as 25 penetrator diameters. If one assumes a 1-m-diameter, then the maximum penetration depth is 25 m. Backman and Goldstein also present the Poncelet equation (1978, p. 38, Equation 6.2 [DIRS 167628]) which, for a 150 kg mass and entrance velocity of 400 m/sec, yields a maximum penetration depth of about 38 m. Other direct input include the empirical results of Patterson (1974 [DIRS 167805]), who reports maximum penetration depth of 20.7 m in an old glacial lake bed; the results from Young (1976, Table II [DIRS 167806]), who reports 67 m in hard dry playa lake soils, and those of Forrestal et al. (1981, p. 28 [DIRS 167630] who records 2.6 m into a welded tough. Dence et al. (1977, p. 262 [DIRS 135253]) suggest that in the 64-kt Pile Driver test, stresses at about 100 m (328 feet) were slightly less than that needed to propagate fractures in granodiorite. Consequently, energy releases of the magnitude required to induce fracturing to depths of interest (i.e., 80 to 100 m, 262 to 328 feet) or over a wide portion of the repository, would require intentional and targeted, deep penetrating, high-yield detonations. By regulatory definition, this is considered as deliberate human intrusion and is excluded under other FEPs. For generic smaller scale crashes and explosions, the energy release is insufficient to significantly affect the repository performance are, therefore, excluded based on low consequence. TSPA Disposition: Not Applicable Related Documents: None ANL-WIS-MD-000019 REV 01 6-69 April 2004 Related FEPs: Administrative control of repository site (1.1.10.00.0A) Accidents and unplanned events during construction and operation (1.1.12.01.0A) Deliberate human intrusion (1.4.02.01.0A) Inadvertent human intrusion (1.4.02.02.0A) Unintrusive site investigation (1.4.03.00.0A) Social and institutional developments (1.4.08.00.0A) Meteorite impacts (1.5.01.01.0A) Urban and industrial land and water use (2.4.10.00.0A) Gas explosions in EBS (2.1.12.08.0A) Supplemental Discussion: Table 6-19. Indirect Inputs for Explosions and Crashes (Human Activities) (1.4.11.00.0A) Reference Input 10 CFR 63.302 [DIRS 156605] NRC definition of human intrusion 40 CFR 197.12 [DIRS 165519] EPA definition of human intrusion 10 CFR 63.2 [DIRS 156605] NRC definition of performance assessment 10 CFR Part 63 [DIRS 156605] NRC regulations 40 CFR Part 197 [DIRS 165519] EPA regulations 40 CFR Part 197 (66 FR 32074, Item 3 “What is the Standard for EPA intent to exclude deliberate intrusion Human Intrusion?” p. 32105 [DIRS 155216]) 66 FR 32127 (66 FR 32074, p. 32127, more specifically Item 10. EPA intent to exclude deliberate intrusion Is the Single–Borehole Scenario a Reasonable Approach to Judge the Resilience of the Yucca Mountain Disposal System Following Human Intrusion? [DIRS 155216]) EPA = U.S. Environmental Protection Agency, NRC = U.S. Nuclear Regulatory Agency 6.2.3.10 Repository Excavation (3.3.06.01.0A) FEP Description: Excavation of the repository and/or its contents may result in the production of tailings, which may subsequently release toxic contaminants. Descriptor Phrases: Excavated rock/tailings left; Human intrusion (excavation) Screening Decision: Excluded – By Regulation and Low Consequence Screening Argument: “Repository Excavation” is excluded from the TSPA–LA based on regulation because the handling of excavation spoils during construction is primarily a preclosure operational concern, whereas the regulatory focus is on postclosure assessment. Furthermore, future mining of the repository for its waste content constitutes human intrusion and postclosure excavation of repository contents would constitute deliberate human intrusion. Additionally, the ANL-WIS-MD-000019 REV 01 6-70 April 2004 surface facilities will be removed and the surface restored prior to closure. By explanation of the concept of performance assessment, the NRC at 10 CFR 63.102(j) [DIRS 156605], clarifies that a performance assessment is to demonstrate compliance with the postclosure performance objectives. Given that excavation of the repository host horizon will occur at the outset of the construction phase, the creation and handling of excavation spoils is a preclosure concern. At 10 CFR 63.311(a) ([DIRS 156605]), the NRC indicates that the preclosure requirement is to be based on protection of the RMEI against radiation exposures and releases of radioactive material. The regulation does not specify chemical toxicity as a preclosure performance criterion, nor does it require the estimation of health effects resulting from non-radiological toxicity. This is consistent with exclusion of FEP 3.3.07.00.0A (Non-radiological toxicity/ effects). Furthermore, future mining of the repository for its waste content constitutes human intrusion and postclosure excavation of repository contents would constitute deliberate human intrusion and is therefore excluded. The regulations at 10 CFR 63.322(f) ([DIRS 156605]) and 40 CFR 197.26(e) ([DIRS 165519]), indicating that only radionuclides transported to the saturated zone be considered, preclude the consideration of human-intrusion FEPs related to the exposure of the public, drillers, or other human intruders from cuttings, circulated materials, or tailings. The preamble to 10 CFR Part 63 (66 FR 55732, Supplementary Information, 3.10 Human Intrusion Standard, p. 55761 [DIRS 156671]) states the following: Human intrusion has the potential for releasing particulate HLW to the surface with drill cuttings or providing a fast pathway for radionuclides to be transported to the SZ by water (e.g., water enters the waste package, releases radionuclides, and transports radionuclides by way of the borehole to the SZ). NAS concluded, and the Commission agrees, that analysis of the risk to the public or the intruders (i.e., drilling crew) from radioactive drill cuttings left unattended at the surface for subsequent dispersal into the biosphere would not fulfill the purpose of the human intrusion calculation because it would not show how well a particular repository site and design would protect the public at large. Rather, an analysis of the hazard of particulate HLW left on the surface would be dominated by assumptions subject to significant speculation and uncertainty regardless of the particular site or design under evaluation. Additionally, the release to the surface represents a one-time release with no long-term effect on the repository barriers. Within context, this statement is strictly directed towards concern with excavated waste rather than initial excavation tailings. However, the reasoning that materials left at the surface represent a one-time release with no long-term effect on the repository barriers is equally applicable to the initial excavation spoils. This is because the spoils resulting from excavation of the repository would consist of naturally occurring materials. No chemical additives or chemical-based slurrying of the spoils will be used during excavation, and no organic materials (aside from the potential for trace amounts of machinery-related fluids such as lubrication oils, grease, or hydraulic fluids) will be introduced to the spoils. By deduction, the spoils will be ANL-WIS-MD-000019 REV 01 6-71 April 2004 similar in composition to naturally occurring alluvial materials already present in the washes and drainage channels existing at Yucca Mountain, and organic contaminants are not of concern. By deduction, the resulting leachate from these materials would likely be similar to the existing groundwater found in the alluvial materials. Consequently, there is no mechanism for the leachate to be of concern with regard to degradation of the repository barriers. Repository excavation is therefore excluded based on regulations and low consequence. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Mining and other underground activities (1.4.05.00.0A) Altered soil or surface water chemistry (1.4.06.01.0A) Geochemical interactions and evolution in the SZ (2.2.08.03.0A) Geochemical interactions and evolution in the US (2.2.08.03.0B) Urban and industrial land and water use (2.4.10.00.0A) Supplemental Discussion: Table 6-20. Indirect Inputs for Repository Excavation (3.3.06.01.0A) Reference Input 40 CFR 197.26(e) [DIRS 165519] Only groundwater transport needs to be considered 6.2.4 Miscellaneous Geologic and Astronomic Features, Events, and Processes This set of FEPs is related to affects of heat on the biosphere, to the geologic setting, or to extraterrestrial processes and events. Direct Inputs used in this Section originating from YMP-controlled sources or NRC regulations are listed in Section 4 and its subsections and no further discussion beyond that provided in Section 4 is required for such sources. Non-YMP sources of direct input are also cited in Section 4. Such sources and corroborating information are discussed in Attachment II of this analysis report. Attachment II discusses non-YMP originating source information related to various FEPs such as diagenesis, extraterrestrial events and earth tides. Attachment IV specifically addresses source information specifically related to meteorite-impact analyses. ANL-WIS-MD-000019 REV 01 6-72 April 2004 6.2.4.1 Metamorphism (1.2.05.00.0A) FEP Description: This FEP addresses regional metamorphism, which has the potential to affect the long-term performance of the repository if it occurs. Metamorphic activity is defined as solid-state recrystallization changes to rock properties and geologic structures through the effects of heat and/or pressure. Descriptor Phrases: Geologic change (metamorphism) Screening Decision: Excluded – Low Probability (not credible) and Low Consequence Screening Argument: “Metamorphism” is excluded from the TSPA–LA based on low probability because the conditions and time required for metamorphic process near Yucca Mountain are such that metamorphism is not credible within a 10,000-year period, and on low consequence because contact metamorphism may occur only over a limited area and at a low probability. For purposes of the FEP screening, the discussion is limited to regional scale and contact metamorphism. The definition of regional metamorphism applied herein refers to the processes by which rocks are changed by the action of heat and pressure at depths of a few kilometers beneath the earth’s surface (i.e., the onset of metamorphic conditions correspond to T of 150-200°C at pressures of 0.5 to 1 kilobars, and depths of 4 to 5 kilometers, as taken from Ehler and Blatt (1972, p. 566) [DIRS 167802]). Alternately, metamorphism may occur in the vicinity of magmatic activity (referred to herein as contact metamorphism). Changes in sediments and rocks at lesser conditions are referred to as diagenesis. See FEP 1.2.08.00.0A Diagenesis, in Section 6.2.4.5 of this analysis report. See also Bates and Jackson 1984, pp. 137 and 322 DIRS 28109], and Berry and Mason 1959, p. 240 [DIRS 135236] for additional definitions. Regional metamorphism is dependent on regional tectonic deformation at Yucca Mountain and is, therefore, dependent on the strain accumulation rates and on slip rates. Savage et al. (1999, . 17627 [DIRS 118952]) present an evaluation of the strain accumulation rate at Yucca Mountain, Nevada for the period 1983 to 1998. Savage et al. 1999, p. 17627 [DIRS 118952] indicate that the strain rate in the Yucca Mountain area is very low, equivalent to 2 nanostrain/yr. The Savage et al. study also addresses alternative interpretations indicating higher strain rates (on he order of 50 nanostrain/yr presented by Wernicke et al. (1998 [DIRS 103485]). Whether the strain rates from Savage et al. or Wernicke et al. are considered, the strain rate has resulted in cumulative fault slip rates of 0.001–0.03 mm/yr (BSC 2004, Table 6 [DIRS 168030]). These strain rates and resulting local cumulative fault slip rates suggest the mechanisms leading to metamorphic activity, deep burial in particular, will also occur at a slow rate. The rate of subsidence (vertical movement leading to deep burial) will be controlled by movement along the block-bounding faults and, at maximum, approximates the cumulative rate of fault slip at Bare Mountain and Yucca Mountain. The local cumulative fault slip rate is low (0.001–0.03 mm/yr) (BSC 2004, Table 6 [DIRS 168030]). A slip rate of 0.03 mm/yr would result in a vertical movement of only approximately 0.3 m (1 foot) in a 10,000-year period. A ANL-WIS-MD-000019 REV 01 6-73 April 2004 0.3-m (1-foot) vertical movement is insufficient to result in pressure and temperature conditions conducive to regional metamorphism of T >150-200.C and pressures on the order of a 0.5 to 1 kilobar and depths of 4-5 kilometers. An expected, typical geothermal gradient may range from 10 to 25ºC per kilometer. By way of comparison, the geothermal gradient, measured in 300- to 600-m-deep borings at Yucca Mountain is approximately 30°C/km (Sass et al. 1988, pp. 38–39 [DIRS 100644]), which agrees with the temperature gradient indicated by Press and Siever (1978, p. 298 [DIRS 167965]). A typical value for pressure gradients from geostatic loading is about 0.6 kbar/km (Ehlers and Blatt (1982, p. 169, Figure 6-3 [DIRS 167802]), although Press and Siever (1978, p. 298 [DIRS 167965]) indicate a pressure gradient on the order of 0.2 bar/km. Additionally, the locus of subsidence has moved to the southwest corner of the basin, away from Yucca Mountain (Fridrich 1999, p. 189 [DIRS 118942]). Because the repository block itself will not be significantly affected by present subsidence rates within 10,000 years, this FEP is excluded based on low consequence. Contact metamorphism is by definition associated with igneous activity, and at Yucca Mountain is a localized rather than regional phenomenon. Further discussion, is therefore, beyond the scope of this FEP. Contact metamorphism is more fully addressed as part of the disruptive events FEP evaluation for FEP 1.2.04.02.0A (Igneous activity changes rock properties). In summary, metamorphism refers to the processes by which rocks are changed by the action of heat (T>150-200°C) and pressure at depths (usually a few kilometers and at pressures on the order of a few kilobars) beneath the Earth’s surface or in the vicinity of magmatic activity. Regional metamorphism requires significantly increased pressure (generally resulting from burial on the order of kilometers), increased temperatures (T> 150-200°C) and long periods of geologic time (millions of years) to occur. At Yucca Mountain, development of these conditions is dependent on the rate of active tectonism and would require several million years to develop and is therefore of low probability within the next 10,000 years. Because the repository block will not be significantly affected, metamorphism does not provide a mechanism to affect dose within the repository performance period (10,000 years). Therefore, “Metamorphism” is excluded from the TSPA–LA based on low consequence. Contact metamorphism is addressed in a related FEP. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Tectonic activity–large scale (1.2.01.01.0A) Faulting (1.2.02.02.0A) Igneous activity causes changes to rock properties (1.2.04.02.0A) Diagenesis (1.2.08.00.0A) Seismic activity changes porosity and permeability of rock (2.2.06.01.0A) Seismic activity changes porosity and permeability of faults (2.2.06.02.0A) Seismic activity changes porosity and permeability of fractures (2.2.06.02.0B) Effects of subsidence (2.2.06.04.0A) Geochemical interactions and evolution in the UZ (2.2.08.03.0B) Geochemical interactions and evolution in the SZ (2.2.08.03.0A) ANL-WIS-MD-000019 REV 01 6-74 April 2004 Supplemental Discussion: Table 6-21. Indirect Inputs for Metamorphism (1.2.05.00.0A) Reference Input Bates and Jackson 1984, pp. 137 and 322 Definition [DIRS 128109] Berry and Mason 1959, p. 240 [DIRS 135236] Definition Savage et al. 1999, p. 17627 [DIRS 118952] Strain accumulation rate Wernicke et al. 1998 [DIRS 103485] Alternative interpretations of strain conditions Sass et al. 1988, pp. 38 to 39 [DIRS 100644] Geothermal gradient at Yucca Mountain Press and Siever 1978, p. 298 [DIRS 167965] Geothermal and pressure gradients Fridrich 1999, p. 189 [DIRS 118942] Locus of subsidence moving southwest 6.2.4.2 Diagenesis (1.2.08.00.0A) FEP Description: This FEP addresses natural processes that alter the mineralogy or other properties of rocks after the rocks have formed under temperature- and pressure-conditions normal to the upper few kilometers of the earth's crust. Diagenesis includes chemical, physical, and biological processes that take place in rocks after formation but before eventual metamorphism or weathering. This FEP refers only to naturally occurring diagenetic processes. Descriptor Phrases: Geologic change (diagenesis) Screening Decision: Excluded – Low Consequence Screening Argument: “Diagenesis” is excluded from the TSPA–LA based on low consequence because the diagenetic effects are generally favorable with regard to infiltration, reversible in nature, and occur over a prolonged time-scale. The time required for complete diagenesis in the shallow environment (extending from the surface to the downward limit of evapotranspiration) is potentially within the timescale of concern for the repository performance assessment (i.e., 10,000 years, see Lattman and Simonberg 1971, p. 277 [DIRS 129306]; and Krystinik 1990, p. 8-1 [DIRS 135295]). Thus, diagenesis cannot be excluded based on low probability. The two primary mechanisms for early and shallow diagenetic changes are compaction and cementation. Krystinik (1990, p. 8-3 [DIRS 135295]) indicates that initial compaction may reduce eolian sediments by as much as 20 to 20 percent, but that after the initial compaction “compaction does not become and important factor in diagenesis until the onset of grain deformation and pressure solution during deeper burial diagenesis. The geologic setting of Yucca Mountain, however, is one of minimal rates of subsidence (see FEP 1.2.05.00.0A Metamorphism, in Section 6.2.4.1 of this analysis report, for discussion of subsidence rates). ANL-WIS-MD-000019 REV 01 6-75 April 2004 Consequently, deep burial and significant compaction is not a credible diagenetic mechanism at Yucca Mountain within the repository performance period (10,000 years). Cementation, however, may be of interest. The predominance of SiO2 cements at Yucca Mountain is documented in Taylor (1986, Figure 9 [DIRS 102684]), who indicates that the accumulation rate of CaCO3, while occurring, is significantly less that that for SiO2. This is reflected in statements indicating that carbonate is primarily derived from airborne dust and the opaline SiO2 from in-place weathering of the parent material and that the cementation by opaline SiO2 is common in the study area and that opaline SiO2 accumulation in the soils is favored over that of CaCO3 (Taylor 1986, pp. 31-33 [DIRS 102684]). Taylor also indicates SiO2 cementation, with CaCO3 as accessory cement, is common in the study area. Furthermore, the presence of cements other than CaCO3, such as SiO2 in arid environments, is documented in Krystinik (1990, p. 8-4) [DIRS 135295]). Reeves (1976, p. 110 [DIRS 104303]) indicates that the net effects of shallow diagenesis and associated cementation is to stabilize the surface environment and decrease the net vertical infiltration rate. Whereas Reeves work focused primarily on CaCO3, but also addressed silicious cements, cementation in rhyolitic tuffs, absent a carbonate source, is not a significant process (Lattman 1973, p. 3015 [DIRS 129305]). The predominance of SiO2 cements at Yucca Mountain is an important consideration because Taylor indicates that in the soils studied, in the absence of effective precipitation or drainage to remove newly dissolved silica, it is precipitated elsewhere within the calcrete horizon, or CaCO3 preferentially precipitates after opaline silica bonds adjacent soil grains. Taylor notes that this process may occur without necessarily plugging intervening pores spaces, as suggested by Reeves. Taylor (1986, Chapter 5 [DIRS 02864]) also suggests that the cementation process, particularly for CaCO3 is reversible, and that the material can be redissolved and moved deeper into the soil profile. Modeling results discussed by Taylor suggest that increased precipitation in the future may translocate CaCO3 accumulations to greater depths, where precipitation is greater. Thus for Yucca Mountain alluvial material, it can be concluded that the net effect of infiltration is either minimal or infiltration is likely decreased. Because the time frame of interest is 10,000 years, the potential for effects of climate change on shallow diagenesis must be considered. As direct input, Taylor (1986 Chapter 5 [DIRS 102864]) indicates silts that formed in alluvium and eolian fines of Holocene to early Pliestocene or late Pliocene age near Yucca Mountain are characterized by distinctive trends in the accumulation of secondary clay, CaCO3, and opaline SiO2 that correspond with the ages of the surficial deposits. However, there is no macro- or micromorphological evidence that suggests that silica cementation occurred under climatic conditions cooler and wetter than those of present climate. In contrast, Taylor also states that accumulation rates of these materials during the Holocene can be attributed to several possible climatic scenarios associated with the Holocene-Pliestocene climate change, but suggest that precipitation has not been a limiting factor, and that climatic change was not sufficient to significantly decrease rate of accumulation. Consequently, climate change can be assumed to affect the rate and location of shallow diagenesis due to changes in temperature, precipitation, vegetation, and other less critical factors that control the rate and distribution of diagenetic changes such as cementation. The net effect, however, will be to vary the depth of the cemented horizons (due to dissolution/reprecipitation), ANL-WIS-MD-000019 REV 01 6-76 April 2004 change the composition of the cement materials (due to differing equilibrium conditions), and otherwise drive the diagenetic processes to differing endpoints and redistribute the areas affected, rather than eliminating the net effects of diagenesis. However, the effect of variability in rates and location of infiltration is already addressed in TSPA-LA by varying the infiltration rates associated with varying climatic conditions. The net effect of past diagenesis in the host rocks is included implicitly in the TSPA–LA through the assignment of models and parameters for flow and transport in the unsaturated zone and saturated zone. Mineralogic changes, if any, induced by the repository and occurring over the period of several hundreds of years due to thermal loading, would be of greater consequence at the repository depth than changes resulting near the surface from naturally occurring diagenetic processes in the vadose zone. Repository- induced changes (e.g., geochemical and thermal processes) are addressed by other FEPs and are beyond the scope of the naturally occurring process that is the focus of this FEP. Although the changes might be similar due to increased temperatures, the naturally occurring changes at depth would occur over a period on the order of several thousand years rather than in several hundreds of years. Furthermore, uncertainty in rates and location of infiltration are already addressed in the TSPA–LA by varying the infiltration rates associated with the varying climatic conditions, which tends to dominate other flow rate uncertainties. This FEP, therefore, is excluded based on low consequence. A brief overview of some of the above listed information is provided in the Supplemental Discussion at the end of this section of the analysis report. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Igneous activity changes rock properties (1.2.04.03.0A) Metamorphism (1.2.05.00.0A) Erosion/denudation (1.2.07.01.0A) Deposition (1.2.07.02.0A) Climate change, global (1.3.01.00.0A) Seismic activity changes porosity and permeability of rock (2.2.06.01.0A) Seismic activity changes porosity and permeability of faults (2.2.06.02.0A) Seismic activity changes porosity and permeability of fractures (2.2.06.02.0B) Geochemical interactions and evolution in the UZ (2.2.08.03.0B) Geochemical interactions and evolution in the SZ (2.2.08.03.0A) Supplemental Discussion: Bates and Jackson (1984, p. 137 [DIRS 128109]) define two types of diagenesis. Mineralogically, it is defined as “the geochemical processes or transformations that affect clay minerals before burial in the marine environment.” Sedimentologically, it is defined as “all the changes undergone by a sediment after its initial deposition, exclusive of weathering and metamorphism. It includes those processes (such as compaction, cementation, replacement) that occur under conditions of pressure and temperature that are normal in the outer portion of the ANL-WIS-MD-000019 REV 01 6-77 April 2004 earth's crust, and according to most United States geologists it includes changes occurring after lithification.” Bates and Jackson (1984, p. 137 [DIRS 128109]) further state that “There is no universally accepted definition of the term, and no delimitation, e.g., with metamorphism.” A prelithification definition has been used by Thrush (1968, p. 320 [DIRS 106989]) and Berry and Mason (1959, p. 233 [DIRS 135236]). Post-lithification changes in rock that change grain size, develop new minerals, or destroy previously existing minerals are typically considered to be alteration (Thrush 1968, p. 30 [DIRS 106989]) or metamorphism (Thrush 1968, p. 699 [DIRS 106989]) rather than diagenesis, although the terms are sometimes used interchangeably or in conjunction. The majority of literature on diagenesis focuses on sedimentary deposits and diagenetic processes that have occurred in clastic or carbonate sedimentary environments. The history of the studied deposits is typically characterized as fluvial or marine deposition (either as clastic deposition or chemical precipitation) during and followed by an extended period of deep burial (>1 km). The geologic system at Yucca Mountain, however, is characterized by erosion and exhumation of lithified igneous materials, rather than deposition and burial of clastic or carbonate sedimentary sequences. Consequently, for the evaluation of Yucca Mountain FEPs, diagenesis is being expanded to include alteration of volcanic rocks at pressures and temperatures below metamorphic conditions, and lithification processes that may occur in surficial deposits. The Viability Assessment of a Repository at Yucca Mountain (DOE 1998, Section 6.1 [DIRS 100548]) provides an extensive discussion of diagenesis of the volcanic rocks at Yucca Mountain. The host rock unit present at Yucca Mountain is a welded tuff. Diagenesis has modified rocks at Yucca Mountain in the past, and will continue to do so in the future. Diagenesis has resulted in the formation of secondary zeolite and clay minerals. Much of this change has occurred shortly after deposition of the volcanic rocks. Additional change has continued at a slower rate throughout the last 10 million years, subsequent to deposition of the tuffs. Note that the products of past diagenesis in the welded tuffs are included implicitly in the TSPA–LA through the assignment of models and parameters for flow and transport in the saturated zone and unsaturated zone. Surficial Quaternary deposits occur at the Yucca Mountain site and in the region. These deposits result from the weathering of parent geologic material (rhyolitic tuffs), and subsequent erosion and redeposition. On Yucca Mountain, these surficial deposits are present as alluvial and colluvial fans and fan remnants and as deposits in stream channels. In the Amargosa Desert, they are present as valley-fill material. The primary lithification processes affecting these surficial deposits are compaction and cementation, which in turn decrease infiltration rates. The variance in infiltration rates based on soil types is currently incorporated into the infiltration models for the Yucca Mountain region. Compaction/Consolidation–The primary diagenetic processes of concern for Yucca Mountain include compaction and cementation. Compaction due to burial can result in a significant decrease in porosity with time. Palmer and Barton (1987, Figure 3 and pp. 32 and 39 [DIRS 118483]) indicate that compaction due to burial of uncemented Tertiary-age sands reduced the in situ porosity by about 12 to 13 percent of the initial porosity, while Berner (1980, ANL-WIS-MD-000019 REV 01 6-78 April 2004 Figure 3.2 [DIRS 128110]) suggests that a 40 to 50 percent decrease is possible, assuming a consistent and continuing burial process. Cementation–A second diagenetic process is cementation. In most arid and semi-arid environments, cementation occurs due to formation of calcium carbonate or other carbonate cements (Reeves 1976, p. 7 [DIRS 104303]; and Lattman 1973, p. 3014 [DIRS 129305]). This may be expressed as formation of layers or fracture infills in the near surface environment. However, the formation of carbonate cements is dependent on the presence of a source of the carbonate ion. Lattman (1973 [DIRS 129305]) conducted studies on fan deposits near Las Vegas, Nevada. The results indicate that alluvial fans in Nevada that consist of silicic igneous materials (such as those composed of rhyolite and rhyolitic tuffs) are “almost always very poorly cemented, showing little more than a few scattered, coated pebbles in weak calcic horizons. Even where, as in Las Vegas Basin, large quantities of calcareous dust are available, the cementation is very weak.” Lattman (1973, p. 3022 [DIRS 129305]). Krystinik (1990, p. 8-8 [DIRS 135295]), however, discusses the role of other cementitious materials during diagenesis of surficial (eolian) deposits in arid environments, and also notes that weathering can reverse the previous effects of diagenesis by removing earlier cements and allowing deflation to occur (Krystinik 1990, p. 8-3 [DIRS 135295]). Krystinik (1990, p. 8-4) indicates for eolian deposits, that in dry sand, diagenesis on the surface of active dunes occurs “in the form of minor chemical degradation of grains, rock-flour mortar, and as amorphous silica, iron, and aluminum oxy-hydroxide grain coatings”. The cited study also notes that observed cements in damp sand included amorphous iron silica, aluminum, and lesser percentages of calcite, smectite, and sodium carbonate. Krystinik (1990, as stated and inferred from pp. 8-4 and 8-8, and Table 2 [DIRS 135295]) also notes that the solutes in water associated with these cements are “remarkably similar” to examples of water from granitic/igneous source terranes documented by others. Reeves (1976, p. 28 [DIRS 104303]) indicates that indurated soil horizons, due principally to silica cementation, are termed “duripans” in the U.S. and silcrete or silcrust in Australia and other countries. Reeves (1976, p. 29 [DIRS 104303]) also mentions that near-surface silica hardpans occur in granitic alluvium in the San Joaquin Valley, discusses the factors that favor silica versus carbonate cementation, and also mentions that many carbonate caliches contain measurable quantities of silica. Duripans and/or petrocalcic layers are common in the soil descriptions provided in the FEIS (DOE 2002, Table 3-20 [DIRS 155970]). It is possible that these deposits could experience additional cementation. Such cementation of deposits mantling Yucca Mountain could affect future rates of moisture infiltration or cementation in deposits composing the alluvial aquifer downgradient of Yucca Mountain. As indicated above, however, increases in cementation tend to decrease the porosity and permeability of deposits. Thus, it is unlikely that cementation will significantly increase infiltration or flow rates. Rate of Diagenesis of Shallow Deposits–Humphrey et al. (1986, pp. 77 to 78 [DIRS 118461]), in their study of the diagenesis and carbonate cementations of the Smackover Formation of Louisiana, indicate that “rates of mineralogic stabilization differ in the various diagenetic environments.” For the materials studied on various carbonate islands, however, “mineralogic ANL-WIS-MD-000019 REV 01 6-79 April 2004 stabilization in the meteoric phreatic zone goes to completion within a few thousand years.” They further state that rates of mineralogic stabilization in the shallow vadose zone (i.e., the downward limit of the zone of evapotranspiration) may be comparable to those of the meteoric phreatic environment. By contrast, Humphrey et al. (1986, p. 78 [DIRS 118461]) also cite studies from carbonate sequences that indicate incomplete diagenesis in the deep vadose zone even after 200,000 years. Dependence on Climate–Reeves (1976, pp. 84 to 87 [DIRS 104303]) indicates that the ideal environment for caliche formation appears to be neither excessively arid nor excessively humid, and that caliche formation can occur over a wide range of climatic conditions. Reeves (1976, p. 86 [DIRS 104303]) further states that: Certainly, the vast mineralogical differences between calcium carbonate and silica, yet the juxtaposition of both minerals in caliche, is prima facia evidence of significant changes in soil chemistry… Because soil chemistry is affected by so many variables, such as temperature, parent material, vegetation, time and topography, it is impossible to describe a singular causative environmental factor for caliche formation. Birkeland (1974, p. 234 [DIRS 128113]) and Reeves (1976, Figure 4-10 [DIRS 104303]) cite studies that suggest that the depth to calcareous horizons (i.e., pedocals) is closely related to the amount and timing of precipitation. Increased precipitation generally results in a greater depth to the calcic horizon. Table 6-22. Indirect Inputs for Diagenesis (1.2.08.00.0A) Reference Input Humphrey et al. 1986, pp. 77–78 [DIRS 118461] Taylor 1986, Chapter 5 [DIRS 102864] Bates and Jackson 1984, p. 137 [DIRS 128109] Definition of diagenesis Thrush 1968, p. 320 [DIRS 106989] Definition of diagenesis Berry and Mason 1959, p. 233 [DIRS 135236] Definition of diagenesis Thrush 1968, p. 30 [DIRS 106989] Definition of alteration Thrush 1968, p. 699 [DIRS 106989] Definition of metamorphism Viability Assessment of a Repository at Yucca Mountain Diagenesis at Yucca Mountain (DOE 1998, Section 6.1 [DIRS 100548]) Palmer and Barton (1987, Figure 3 and pp. 32 and 39 Compaction due to burial [DIRS 118483] Berner 1980, Figure 3.2 [DIRS 128110] Compaction due to burial Reeves 1976, p. 7 [DIRS 104303] Cementation in arid environments Lattman 1973 [DIRS 129305] Cementation in southeastern Nevada Lattman 1973, p. 3022 [DIRS 129305] Cementation near Las Vegas, Nevada Krystinik 1990, as stated and inferred from pp. 8-4 and 8Cementation process in eolian environments 8, and Table 2 [DIRS 135295] Reeves 1976, p. 28 [DIRS 104303] Definition of duripans Reeves 1976, p. 29 [DIRS 104303] Hardpans in granitic alluvium DOE 2002, Table 3-20 [DIRS 155970] Humphrey et al. 1986, pp. 77 to 78 [DIRS 118461] Rate of diagenesis in carbonates ANL-WIS-MD-000019 REV 01 6-80 April 2004 Table 6-22. Indirect Inputs for Diagenesis (1.2.08.00.0A) (Continued) Reference Input Reeves 1976, pp. 84 to 87 [DIRS 104303] Conditions for caliche formation Birkeland 1974, p. 234 [DIRS 128113] Depth of calcareous horizon dependent on precipitation Reeves 1976, Figure 4-10 [DIRS 104303] Depth of calcareous horizon dependent on precipitation 6.2.4.3 Salt Diapirism and Dissolution (1.2.09.00.0A) FEP Description: This FEP addresses geologic processes primarily relevant to repositories located in salt deposits. Salt diapirism refers to the tendency of salt to flow under lithostatic loading when density and viscosity contrasts with surrounding strata are favorable. Salt domes are the best-known example of salt diapirism. Salt dissolution can occur when any soluble mineral is removed by flowing water, and large-scale dissolution is a potentially important process in rocks that are composed predominantly of water-soluble evaporite minerals, such as salt. Descriptor Phrases: Geologic change (salt diapirism); Geologic change (salt dissolution). Screening Decision: Excluded – By Regulation Screening Argument: “Salt Diapirism and Dissolution” is excluded from the TSPA–LA based on regulatory requirements because salt deposits and evaporite deposits are not a geologic feature near the repository. The definition of geologic setting at 10 CFR 63.2 ([DIRS 156605]) is “the geologic, hydrologic, and geochemical systems of the region in which the geologic repository is or may be located.” Inclusion of this FEP would be outside the scope and intent stated at 10 CFR 63.21(c)(1) ([DIRS 156605]), which specifies consideration and description of “features, events, and processes outside of the site to the extent the information is relevant and material to safety or performance of the geologic repository.” Furthermore, at 10 CFR 63.114(a), and 10 CFR 63.115(a) ([DIRS 156605]), the regulatory requirements are to “include data that are related to the geology, hydrology, and geochemistry (including disruptive events) of the Yucca Mountain Site, and the surrounding region to the extent necessary …” and to “identify … natural features of the geologic setting, that are considered barriers important to waste isolation.” At 10 CFR 63.305(c) ([DIRS 156605]), DOE is directed to “…vary factors related to the geology, hydrology, and climate based upon cautious, but reasonable assumptions consistent with present knowledge of factors that could affect the Yucca Mountain disposal system over the next 10,000 years.” Evaporite deposits of sufficient volume to develop a diapir or to be of concern for dissolution have not been reported near Yucca Mountain. Rather, Yucca Mountain is located in the southwestern Nevada volcanic field and consists of tilted fault blocks composed of layered sequences of ash flow, ash-fall, and bedded tuffs of Miocene age (BSC2004, Section 6.5.1.4 and ANL-WIS-MD-000019 REV 01 6-81 April 2004 Table 4 [DIRS 168029], as corroborated by Simmons 2004, Section 3.3.4 [DIRS 166960]) and as shown by Day et al., 1998 [DIRS 100027]). Voluminous evaporite deposits do not exist in the vicinity of Yucca Mountain, and the repository is not planned for a salt dome or cavern. This feature and related process of lithologic flow are, therefore, inconsistent with the present knowledge of the geologic setting for Yucca Mountain. Therefore, “Salt diapirism and dissolution” is excluded from the TSPA–LA based on the regulation. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Metamorphism (1.2.05.00.0A) Diapirism (1.2.09.01.0A) Large-scale dissolution (1.2.09.02.0A) Effects of subsidence (2.2.06.04.0A) Salt creep (2.2.06.05.0A) Supplemental Discussion: Table 6-23. Indirect Inputs for Salt Diapirism and Dissolution (1.2.09.00.0A) Reference Input Simmons 2004 Section 3.3.4 [DIRS 166960] Lithology at Yucca Mountain Day et al. 1998 [DIRS 100027] Geology at Yucca Mountain 6.2.4.4 Diapirism (1.2.09.01.0A) FEP Description: The process by which plastic, low density rocks (most commonly evaporites) may flow under lithostatic loading when density and viscosity contrasts with surrounding strata are favorable. Such a process would modify the groundwater flow regime and affect radionuclide transport. Descriptor Phrases: Geologic change (diapirism) Screening Decision: Excluded – By Regulation Screening Argument: “Diapirism” is excluded from the TSPA–LA based on regulatory requirements because geologic conditions suitable to diapirism are not a geologic feature in the vicinity of the repository. In the broadest sense, diapirism encompasses “the piercing or rupturing of domed or uplifted rocks by mobile core material, by tectonic stresses as in anticlinal folds, by the effect of geostatic load in sedimentary strata as in salt domes or shale diapirs, or by igneous intrusions, forming diapiric structures such as plugs” (Bates and Jackson 1984, p. 138 [DIRS 128109]). The concept of diapirism is usually applied to salt structures resulting from geostatic loading. ANL-WIS-MD-000019 REV 01 6-82 April 2004 FEP 1.209.00.0A (Salt diapirism) is addressed in Section 6.2.4.3 of this analysis report and is excluded by regulation. There is no past evidence of other forms of diapirism within the geologic setting at Yucca Mountain. Current tectonic stresses in the region are extensional (BSC 2004, Section 6.3.1 [DIRS 168030]), and an extensional stress regime is not conducive to compression-related anticlinal folding and doming associated with diapirism. The geologic materials at Yucca Mountain are brittle (particularly the welded tuffs), and have exhibited deformation by faulting and jointing, or formation of breccias rather diapirism. The volcanic rocks present at the site are not capable of ductile flow under the stresses and at the temperatures expected to result at the site due to geostatic loading and waste emplacement. In general, ductile behavior is associated with increased temperatures and increased hydrostatic pressures and is expected at deep levels of the earth’s crust and in the mantle. However, Yucca Mountain is located in an area of only moderate heat flow in the Southern Great Basin, and lies south of the regions that might be more conducive to diapirism as indicated by relatively high crustal heat flow (Lachenbruch and Sass 1978, pp. 212 and 246 [DIRS 142990]). Hence, further consideration of diapirism related to tectonic stresses and geostatic loading is precluded at 10 CFR 63.2, 10 CFR 63.21(c)(1), 10 CFR 63.114(a), 10 CFR 63.115(a), and 10 CFR 63.305(c) ([DIRS 156605]) because the necessary geologic materials and stress environment do not occur at Yucca Mountain. Diapirism related to igneous intrusion is relevant to the disruptive scenario for igneous intrusion. Because of the stress regime at Yucca Mountain, an igneous event is most likely to be in the form of dikes, as discussed in BSC 2003 (Section 6 [DIRS 163769]. These dikes will be oriented subparallel to the direction of existing groundwater flow and faults and fractures (and, therefore, of minimal impact on groundwater flow systems), or in the form of sills, as opposed to significant vertical changes due to uplift or doming events related to igneous-induced diapirism. By way of corroboration, Smith et al. (1998, p. 155 [DIRS 118967]) point out that extension is accommodated in the upper crust by intrusion of vertical dikes perpendicular to the extension direction, with surface deformation possibly including open fissures, monoclines, normal faults, and grabens, and with surface uplift being approximately a few meters (Smith et al. 1998, Figure 2 [DIRS 118967]). Therefore, the igneous aspect of diapirism is excluded based on low consequence. The potential for hydrologic response to igneous activity is more fully evaluated in the FEP 1.2.10.02.0A (Hydrologic response to igneous activity), which is shared by multiple FEP AMRs. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Igneous activity changes rock properties (1.2.04.02.0A) Igneous intrusion into repository (1.2.04.03.0A) Salt diapirism and dissolution (1.2.09.00.0A) Hydrologic response to igneous activity (1.2.10.02.0A) Salt creep (2.2.06.05.0A) ANL-WIS-MD-000019 REV 01 6-83 April 2004 Supplemental Discussion: Table 6-24. Indirect Inputs for Diapirism (1.2.09.01.0A) Reference Input (Bates and Jackson 1984, p. 138 [DIRS 128109] Definition of Diapirism Lachenbruch and Sass 1978, pp. 212 and 246 [DIRS Regional crustal heat flow 142990] Smith et al. 1998, p. 155 [DIRS 118967] Features associated with dike intrusion 6.2.4.5 Meteorite Impact (1.5.01.01.0A) FEP Description: Meteorite impact close to the repository site might disturb or remove rock so that radionuclide transport to the surface is accelerated. Possible effects include alteration of flow patterns (faults, fractures), changes in rock stress, cratering and exhumation of waste. Descriptor Phrases: Meteorite impact (flow and pathway changes); Meteorite impact (exhumation). Screening Decision: Excluded – Low Probability and Low Consequence Screening Argument: “Meteorite impact” is excluded from the TSPA–LA based on low probability and low consequence. The FEP analysis is dependent on the probability of occurrence of various size impact craters, the area and relative dimensions of the repository footprint, and the depth of the repository below the ground surface. The probability of an impact crater of a given size occurring directly over or adjacent to the repository is dependent on the total flux of meteorites to the earth surface and the repository foot print area (or target area). The size of the crater of interest is determined by the depth from ground surface to the top of the repository, the depth of any intervening geologic layers of particular interest due to their physical or hydrologic properties, and the spatial relationship of crater diameter to the associated exhumation depth and fracture depth. The annualized probability threshold for consideration is 10-8, as explained in Assumption 5.1 of this analysis report. Detailed probability calculations, and a thorough discussion of meteorite impact probability and cratering information provide the technical basis for exclusion. These calculations and related detailed discussion are provided in Attachment IV of this analysis report. The analysis is based on direct input for meteorite characteristics and cratering statistics, all of which were taken from published literature, as described in Attachment II of this analysis report. The initial evaluation indicated that only simple cratering effects needed to be considered, due to the low probability of large crater diameters associated with complex cratering. This was based on Grieve (1987, p. 249 [135254]); Grieve et al. (1995, p. 184 [135260]); and Wuschke et al.(1995, p. 3 [DIRS 129326]). The relationship of energy release, crater diameter, and the spatial relationship of crater diameter to extent and depth of cratering effects was derived from a ANL-WIS-MD-000019 REV 01 6-84 April 2004 variety of sources, including: Dence et al. (1977, pp. 250 and 261–264 [DIRS 135253]); Grieve (1998, p. 113 and Figure 3 [DIRS 163385]); and Wuschcke et al. (1995, p. 3 and Figure 1 [DIRS 129326]). Cratering rate distributions for the repository area were developed based on distributions and/or equations presented by Grieve (1987, pp. 249 and 257, and Figure 8 [DIRS 135254]), and from Wuschke et al. (1995, pp. 4 and 26 [DIRS 129326]). Meteorite flux mass and size information was derived from Ceplecha (1992, p. 362 and Figure 1 [DIRS 135242]), and was further refined by type of material and related densities based on Ceplecha (1994, p. 967, Tables 1, 3, and 4, Figure 2 [DIRS 135243]) and Shoemaker (1983, pp. 464 and 480 [DIRS 135308]). This was coupled with the work from Hills and Goda (1993, pp. 1140 and 1142, Figures 9, 16, 17, and 18 [DIRS 135281]) to translate initial meteor radius to resulting crater radius and other effects, to produce a distribution of crater diameters based on meteoroid flux to earth. The calculations are also based on a minimum depth to the repository of approximately 200 m (656 feet). Drawing 800-IED-WIS0-00103-00101-000-00A (BSC 2004 [DIRS 168370]) indicates that the overburden thickness from emplacement area to topographic surface is 215 m. A depth of 200m will be used in the calculation to provide a small margin of conservatism. Also of interest is the minimum depth to a key geohydrologic unit. In the easternmost portion of the repository, the depth of the unit is approximately 60 m (196 feet), as described in Attachment IV of this analysis report. This unit, however, is significantly deeper over the remainder of the repository due to topographic changes to the west. The unit outcrops west of the ridgeline of Yucca Mountain, but at a location not overlying the repository footprint. The FEP is excluded based on low probability for exhumation and fracturing to repository depth and based on low consequence for increased infiltration in the unsaturated zone that could result from a meteorite impact in the repository area or outcrop area adjacent to the waste emplacement area. As calculated in Attachment IV of this analysis report, and based on the TSPA-LA footprint design and using conservative assumptions for meteor entry velocity, the crater diameter (i.e., 20 to 80 m) that corresponds to the 10-8 annualized exceedance probability is of insufficient size to exhume waste or produce a crater whose fractures reach the repository depth. Larger crater diameters occur less frequently, are, therefore, of lower probability, and are excluded from the TSPA–LA. Smaller crater diameters occur more frequently, but are of insufficient size to result in direct exhumation or fracturing to the depth of the repository and are, therefore, excluded for exhumation and fracturing to repository depth based on low consequence. As discussed in UZ Flow Models and Submodels report (BSC 2004, Sections 6.1.2 and 6.2.2 [DIRS 168027]), the characteristics of groundwater movement through specific rock units differ based on hydrogeologic properties. Water that infiltrates into the Tiva Canyon welded unit can be transported rapidly through fractures as deep as the underlying Paintbrush nonwelded unit. Due to its high porosity and low fracture density, the Paintbrush unit tends to slow and divert the downward velocity of water flow compared to highly fractured units such as the Tiva Canyon unit. However, isotopic (chlorine-36) analysis has identified isolated pathways that provide relatively rapid water movement for small amounts of water through the Paintbrush nonwelded unit to the top of the underlying Topopah Spring welded unit. Due to increased fracturing in the Topopah Spring welded unit, water has the potential to travel more rapidly through the unit. Consequently, fracturing of the geologic units above the repository is of concern from the ANL-WIS-MD-000019 REV 01 6-85 April 2004 standpoint of altering flow paths, because increased fracturing of the PTn could potentially result in increased downward groundwater flux. The particular zones of interest include the Pah Canyon and Topopah Spring subzones of the Paintbrush nonwelded tuff. For this analysis, the depths of these units were obtained from MO0004QGFMPICK.000 [DIRS 152554] based on locations of boreholes within the repository area as shown in Figure 4 of BSC 2004 [DIRS 168029]. Depths are provided in Attachment IV of this report. The analysis shows that the Paintbrush unit is present across the repository footprint and, generally, at depths substantially greater than 60 m at locations overlying the repository footprint. However, in the extreme eastern portion of the repository, the top of this unit can be at a depth of less than 60 m, and it outcrops to the west of the repository. Attachment IV of this analysis report provides four similar probability curves (based on multiple sources) in the two figures, Figures IV-8a (for the TSPA-LA emplacement area only) and Figure IV-8b (for the PTn outcrop area). Similar curves are provided for corroborative purposes on Figures IV-8c and IV-8d for the TSPA-LA footprint siting area and for the previous TSPA-SR repository footprint. The curves in the figures are based in part on the modeling results given in Hills and Goda (1993, pp.1140 and 1142, Figures 16 and 17 [DIRS 135281]). In each figure, one of the curves represents the annualized exceedance probability for crater diameters resulting from the largest meteorite fragment stemming from a meteor with an atmospheric entry velocity of V=15 km/sec and a vertical atmospheric entry angle. Increased entry velocities and angles tend to dissipate more energy and mass into the atmosphere and thus result in decreased crater diameters, as explained in Attachment IV of this analysis report. A distribution of entry velocities and angles is likely the reality, but the distribution of velocity and entry angles is currently not quantifiable. Therefore, a value of V=15 km/sec and vertical entry angle are conservative and used as the basis for the FEP evaluation. The curve for V=15 km/sec indicates resulting crater diameters on the order of 80 m (262 feet) at the threshold probability, and smaller crater diameters at greater probability. A qualitative assessment of the degree of conservatism in using a curve for V=15 km/sec for the largest resulting fragment can be gained by examining the remaining curves on Figure IV-8a. The remaining curves are for an atmospheric entry velocity of V=20 km/sec, the Grieves curve (1987 [DIRS 135254]) and the Wuschke et al. curve (1995 [DIRS 129326]) are based on observed earth cratering diameter distributions. The curves indicate that cratering diameters ranging from 20 to 60 m (66 to 197 feet) occur at the threshold probability. The induced fracture depth from an 80-m (262-feet) diameter cratering event (i.e., a conservative estimate of the largest crater likely at the threshold probability of 10-8 events per year) would extend no deeper than about 60 meters (197 feet) based on fracture depth–to– crater diameter ratio of 0.76, which is discussed in detail in Attachment IV of this analysis report. More realistic crater diameters of 20 to 60 m (66 to 197 feet) suggest extended fracturing to depths of 45 m (148 feet) or less. Depths of less than 60 m (197 feet) would be of low consequence to inflow because they are of insufficient depth to fracture to the top of the units of interest. More frequent, but smaller diameter cratering events would correspondingly result in shallower fracturing depths. For most of the TSPA-LA repository footprint, the fracturing of the Paintbrush nonwelded unit can therefore, be excluded based on low probability because the ANL-WIS-MD-000019 REV 01 6-86 April 2004 probability of fracturing to depths of 60 m (197 feet) or greater (i.e., to the top of the unit) is less than 10-8 per year. For the easternmost portion of the repository, where the units of interest are shallower, it must be demonstrated that the effect of fracturing would be of low consequence. As long as the consequences associated with an 80-m-diameter crater or smaller (that is, the effects from a crater diameter occurring at an annualized exceedance probability equal to or greater than 10-8) are insignificant, then this FEP can be excluded based on low consequence. To that end, an 80-—m-diameter crater encompasses an area of about 0.005 km2 compared to the total repository area(14 km2) used for the basis of the probability calculation, or approximately 0.04 percent of the land surface above the repository, with more frequent but smaller crater diameters encompassing lesser areas. Additionally, BSC 2004 (Figure 6.1-1, [DIRS 168027]) indicates that the smallest model grid block size in the eastern part of the repository encompasses an area of approximately 0.01 km2. Thus, the diameter of the meteorite crater coincident with a 10-8 annualized exceedance probability encompasses about one-half of a single modeling grid block. Because only the eastern portion of the repository site is subject to such effects, because the curve for V=15 km/sec is a conservative assumption with regard to entry velocity and angle, and because of the minimal land surface affected (particularly as modeled for unsaturated zone flow), it is concluded that additional fracturing from meteorite impact occurring at an annual exceedance probability of 10-8 or greater would not significantly alter the modeled unsaturated zone flow conditions used for TSPA-LA. More frequent, but smaller-diameter cratering events would correspondingly result in shallower fracturing depths. Because the depths are insufficient to extend to the top of the geologic units of interest, the more frequent events can be also excluded based on low consequence. As discussed above, the figures in Attachment IV of this analysis report indicate that at an annualized probability of 10-8, the corresponding crater diameter resulting from impact of the largest meteor fragment is likely to range between about 0.02 km to about 0.08 km (20 to 80 m [66 to 262 feet]). Based on Hills and Goda (1993, Figure 9 [DIRS 135281]), the radius of the associated debris swarm (i.e., the degree of scatter of all fragments, but with lesser cratering effects, if any, than the largest fragment) is on the order of 0.4 to 0.5 km, for a meteorite causing an 80-m (262-feet) diameter crater. This suggests a debris field with a total encompassing cratering area of approximately 0.5 to 0.8 km2, but with a pock-marked surface - some portion of the area is affected and some is not depending on the number and size of fragments. Furthermore, some of the debris field may fall exterior to the repository, and many of the craters would be of insufficient depth to significantly affect infiltration. Such an event would only be of concern for the easternmost portions of the repository, due to the shallower depth to the units of concern. At most, consideration of the total area of an 0.5 to 0.8 km2 debris field or crater field, if totally encompassed within the repository footprint, would involve no more than 4 to 6 percent of the 14 km2 surface area, or an equivalent of no more than 50 to 80 of the more than 2,000 surface grid blocks (BSC2004, Figure 6.1-1 [DIRS 168027]) used for the unsaturated zone infiltration modeling. This suggests that an argument for exclusion based on low consequence is appropriate, even if the entire debris field and crater field, rather than just the crater resulting from the largest fragment, is considered. Fracturing of the Paintbrush nonwelded unit above the repository is, therefore, excluded in part on low probability (for crater diameters larger than 80-m-diameter for most of the repository) ANL-WIS-MD-000019 REV 01 6-87 April 2004 and in part based on low consequence (for the easternmost portion of the repository and for crater diameters occurring with probability greater than the threshold probability). With regard to the Paintbrush hydrologic unit outcrop area on the western edge of the repository area, the probability threshold is shown on Figure IV-8b in Attachment IV of this analysis report. The figure indicates that resulting crater diameters from the largest fragment at the threshold probability would be less than 0.02 km (20 m). This is decreased diameter at the threshold probability is due to the decrease in target are of the outcrop compared to that of the repository footprint. A 0.02-km diameter represents a surface area of about 0.0003 km2, or less than 0.002 percent, of the repository surface area and significantly less than a single unsaturated zone model grid block. With regard to a debris field, the width (i.e. the narrow dimension) of the outcrop area is no greater than 0.1 km, thus limiting the affected outcrop area to no more than 0.03 km2 as an upper bound for an event of any size. This would represent about 0.2 percent of the repository surface area used for the calculation. Accordingly, meteorite impact in the outcrop area can also be excluded based on low consequence. Based on Hills and Goda (1993, Figure 18 [DIRS 135281]), meteors that result in crater diameters of 80-m (corresponding with the threshold annual probability of 10-8) could trigger earthquakes with magnitudes ranging from Magnitude 5 to slightly less than Magnitude 7. Existing seismic analyses cover this range of magnitude (see CRWMS M&O 1998, Section 4 [DIRS 103731]). Therefore, a meteorite-caused earthquake is excluded based on low consequence because it would not provide a significant contribution to the earthquake hazard beyond that which is already included and probabilistically weighted in the TSPA-LA. The effects of changes in rock stress, such as those caused by seismic activity, are addressed in multiple FEP AMRs for FEPs 2.2.06.01.0A (Seismic activity changes porosity and permeability of rock); 2.2.06.02.0A (Seismic activity changes porosity and permeability of faults); and 2.2.06.02.0B (Seismic activity changes porosity and permeability of fractures). Given that the FEP screening address postclosure issues, the effects of a near-surface explosion associated with a meteorite are also excluded based on low consequence because above-surface effects are not of concern for the subsurface postclosure repository. Since infiltration is not significantly affected and no fracturing or exhumation occurs down to the repository depth, there is no mechanism for the meteorite impact at the threshold annual probability or greater to affect groundwater flux through the repository horizon. Therefore, the dose and radionuclide release of radionuclides are not significantly changed. The hydrology aspects of the FEP, therefore, are excluded from the TSPA–LA based on low consequence. ANL-WIS-MD-000019 REV 01 6-88 April 2004 TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Climate change (global) (1.3.01.00.0A) Extraterrestrial events (1.5.01.02.0A) Seismic activity changes porosity and permeability of rock (2.2.06.01.0A) Seismic activity changes porosity and permeability of faults (2.2.06.02.0A) Seismic activity changes porosity and permeability of fractures (2.2.06.02.0B) Explosions and crashes (human activity) (1.4.11.00.0A) Supplemental Discussion: There are no indirect inputs for this analysis. 6.2.4.6 Extraterrestrial Events (1.5.01.02.0A) FEP Description: Extraterrestrial events (e.g., supernovae, solar flares, gamma-ray bursters, alien life form) may affect long-term performance of the disposal system. Descriptor Phrases: Extraterrestrial events (climate change); Extraterrestrial events (flow and pathway changes). Screening Decision: Excluded – Low Consequence Screening Argument: “Extraterrestrial events” are excluded from the TSPA–LA based on low consequence because the only resulting identified mechanisms for affecting the repository (climate change and hypothetically, microbial activity) are currently addressed in the TSPA-LA evaluation. The potential mechanisms to link the effect of extraterrestrial events to changes in behavior of engineered and natural systems are not well documented in the scientific literature. In the absence of reputable published work identifying specific mechanisms, evaluating the effect of such events on the postclosure repository performance requires speculation and conceptualization of possible linkages between the event and repository performance. Brakenridge (1981 [DIRS 167873]) discusses the potential effects of Late Quaternary-Age Supernova on the terrestrial paleoenvironment. The paper indicates that over 120 radio-emitting galactic supernova remnants have been cataloged. Using a value of 120 events in the past 15,000 years suggests a rate of approximately one event per 100 years. The most significant of these peak fluxes was for the Vela supernova, which was calculated to have a peak flux of about 40,000 ergs/cm2. The paper indicates that supernova events release on the scale of 1049 to 1050 ergs of gamma radiation and asserts that such an event has the potential to cause ozone depletion in earth’s atmosphere for a period of two to six years and create nitrogen-rich environments at ANL-WIS-MD-000019 REV 01 6-89 April 2004 the earth’s surface. Observable effects are suggested to include kerogen rich sediments at 11 sites worldwide. Included short-term terrestrial effects (i.e., on the scale of 1,000 years), speculatively, would have included global cooling. The paper also asserts that such events could precipitate increased UV-light penetration by ozone layer depletion. The increased intensity could be as much as 2 to 10 times the present level. Aside for the potential impact on C14 dating, no other effects are discussed and no subsurface effects are mentioned. This work is corroborated by Ruderman (1974 [DIRS 167875]) with regard to nitrogen enrichment and ozone depletion, and by Arnold (2003 [DIRS 167638]) and Novotna and Vitek (1991, p. 35 [DIRS 167634]) with regard to climate linkage. The frequency and energy release is corroborated by Karam (2002 [DIRS 167872]), who also addresses the effects of gamma ray bursters, and calculates doses for both supernovae and gamma ray bursters. Karam (2002 [DIRS 167872]) also substantiates the lack of subsurface effects due to shielding and indicates that there is a 10-8 reduction in “typical dose” within the top 20 mm of rock (Karam 2002, Table 1 [DIRS 167872]). Solar-related effects and correlation to changes in earth’s natural systems are captured in Lean (1997 [DIRS 167639]) in the form of a conceptual summary statement, “Numerous associations are evident between solar variability and terrestrial parameters that range from the Earth’s surface to hundreds of kilometers above it, on the time scales from days to centuries.” In particular, Lean points out the decadal cycles in the sun’s activity are evident in temperatures at the earth’s surface and through the atmosphere. Lean also indicates that there is also an apparent association of surface temperature with overall solar activity, but it is unclear weather the sun’s variable radiation is responsible. According to Lean, least certain is the extent to which tenths percent changes in visible and IR radiation modify global surface temperature and climate. Lean also mentions that there is a current inability to adequately quantify all climate and ozone forcings, which adds ambiguities to assessments of the global change. Some of the listed examples of extraterrestrial events (supernovae, solar flares, gamma-ray bursters) are credible and could result in an influx of solar radiation, space radiation, or cosmic rays onto the earth’s magnetosphere. Collectively, this can be referred to as “space weather”. Maynard (1995 [DIRS 160888]), in discussing the uses of “space weather” prediction, which is primarily focused on solar effects, lists several existing and potential customers and the basis of their need for such information. The discussion of the type of operations affected and the problems encountered includes spacecraft operations, satellite operations, GPS-locating operations (which are satellite based), space object tracking, over-the-horizon radar operations, high frequency communications, telecommunications such as transatlantic fiber optic communications, geomagnetically induced currents in power transmission lines and transformers, applied-DC currents for pipeline corrosion mitigation, and semi-conductor manufacturing (likely related to power line fluctuations). This list of systems is corroborated by Lean (2001, pp. 57-61 [DIRS 167639]) and Cole (2003 pp. 299–301 [DIRS 167641]). While these effects may be pertinent to the repository operational concerns or performance confirmation activities, they are unlikely to directly affect long-term performance of the postclosure repository. The effect of any such past events is assumed (see Assumption 5.3 of this analysis report) to be reflected through the range of climatic properties, which were determined from field studies and observations that are currently included within the TSPA-LA. Because the existing data set ANL-WIS-MD-000019 REV 01 6-90 April 2004 includes the range of effects that have occurred in the past, the effects of future changes would be no greater than those already considered, and therefore, the initiating extraterrestrial events are considered to be of low consequence and are excluded. This FEP definition also includes the potential for effects from alien life forms. Aside from the hypothetical potential for microbial influx via meteorites, the presence of alien life forms has not been verified or documented in the scientific literature, is considered to be overly speculative, and is not further evaluated. The potential for effects from alien life forms (other than microbial activity) is judged to be of low probability (not credible) based on the absence of verification of any such life forms in the scientific literature. If the extraterrestrial transfer of microbes is presumed, then introduction into the repository could be postulated. However, microbial affects on the cladding, waste package, and drip shield are already considered under a separate set of FEPs (2.1.02.14.0A, 2.1.03.05.0A, 2.1.03.05.0A), and, as a result, the introduction of extraterrestrial microbes is excluded based on low consequence. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Meteorite impact (1.5.01.01.0A) Changes in the earth's magnetic field (1.5.03.01.0A) Supplemental Discussion: Table 6-25. Indirect Inputs for Extraterrestrial Events (1.5.01.02.0A) Reference Input Ruderman 1974 [DIRS 167875] Affects of extraterrestrial events on the ozone layer Arnold 2003 [DIRS 167638] Linkage of cosmic rays to climate change Novotna and Vitek 1991, p. 35 [DIRS 167634] Linkage of cosmic rays to climate change Karam 2002 [DIRS 167872] Magnitude and frequency of supernovae and gamma bursters Karam 2002 [DIRS 167872] Earth’s shielding effects Lean 2001, pp. 57-61 [DIRS 167639] List of engineered systems affected by space Cole 2003, p. 299-301 [DIRS 167641] List of engineered systems affected by weather ANL-WIS-MD-000019 REV 01 6-91 April 2004 6.2.4.7 Changes in the Earth's Magnetic Field (1.5.03.01.0A) FEP Description: Changes in the earth's magnetic field could affect the long-term performance of the repository. Descriptor Phrases: Climate change (magnetic field reversal) Screening Decision: Excluded – Low Consequence Screening Argument: “Changes in the Earth’s magnetic field” is excluded from the TSPA–LA based on low consequence because no effect on the repository can be identified. Changes and fluctuations in the earth’s magnetic field are relatively common in geologic history. During the last 20 million years, the fossil record shows at least 60 reversals, and the periodicity of the reversal is on the scale of a few hundred thousand years to once every million years (Odenwald 2003 [DIRS 160892]). There has been a decrease in the earth’s magnetic intensity in the last few thousand years, and there is some evidence that a reversal in the earth’s magnetic field may occur sometime during the next few to several thousand years (Odenwald 2003 [DIRS 160892]). The frequency of pole reversals, and the variation in field intensity with time is corroborated by Biggin and Thomas (2003, Figure 11 [DIRS 167876]) and by Hoffman (1995 [DIRS 160891]). This suggests that this FEP, while unlikely, cannot be excluded based on low probability (see Assumption 5.1 of this analysis report). The potential mechanisms to link the effects of magnetic field changes to changes in behavior of engineered and natural systems are not well documented in the scientific literature. In the absence of reputable published work identifying specific mechanisms, evaluating the impact of changes on the postclosure repository performance requires speculation and conceptualization of possible linkages between the event and repository performance. From an operational and performance confirmation activities standpoint, difficulties with location positioning, communications, and electrical circuitry could be affected, but the timeframe of any reversal is well beyond the operational period. Odenwald (2003 [DIRS 160892]) indicates that there are no identifiable fossil mutations or extinctions associated with the previous reversals. No corroborating information regarding the possible effects of a pole reversal or intensity fluctuations was found in the literature search. Only two linkages to earth’s natural systems were found. Pechala (1985, p. 406 [DIRS 167633]) discusses the linkage between the earth’s magnetic field and tropospheric circulation and indicates that some authors use the realtionship as a basis for explaining past changes in earth’s climate. Biggin and Thomas (2003, pp. 409-412 [DIRS 167876]) suggest that the changes in the field result from global-scale tectonic processes such as slab subduction and mantel processes. Among the longer-term possible effects of changes in the earth’s magnetic field, only climate change has a reasonable possibility of affecting the repository. This hypothetically occurs through the complex coupling of the earth’s thermosphere, ionosphere and magnetosphere (Pechala 1985 (DIRS 167633]). However, no clear evidence exists that long-term climate change is connected with magnetic reversals, and, therefore, no basis exists for evaluating the range of possible future effects. As noted above, changes in the earth’s magnetic field are ANL-WIS-MD-000019 REV 01 6-92 April 2004 common in geologic history. The effect of any such past events is assumed (see Assumption 5.3 of this analysis report) to be reflected in the range of climatic properties, determined from field studies and observations, and such changes are included within the TSPA-LA. Because the existing data set includes the range of effects that have occurred in the past, the effects of future changes would presumably be no greater than those already considered, and therefore, they are of low consequence. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Climate change, global (1.3.01.00.0A) Extraterrestrial events (1.5.01.02.0A) Supplemental Discussion: Table 6-26. Indirect Inputs for Changes in the Earth's Magnetic Field (1.5.03.01.0A) Reference Input Biggin and Thomas 2003, Figure 11 [DIRS 167876] Frequency of pole reversals and variations in intensities Hoffman 1995 [DIRS 160891] Frequency of pole reversals and variations in intensities Biggin and Thomas 2003, pp. 409-412 [DIRS 167876] Relationship of geodynamics to magnetic field behavior Pechala 1985 (DIRS 167633] Link for magnetic field and tropospheric circulation 6.2.4.8 Earth Tides (1.5.03.02.0A) FEP Description: Small changes of the gravitational field due to celestial movements (sun and moon) that cause earth tides and that may, in turn, cause pressure variations in the groundwater flow systems. Descriptor Phrases: Earth tides (flow and pathway changes) Screening Decision: Excluded – Low Consequence Screening Argument: “Earth tides” is excluded from the TSPA–LA based on low consequence because the magnitude of water level fluctuations is insignificant and is embedded in existing water level records. Earth tides are an ongoing phenomenon and are reflected as rhythmic, measurable pressure increases and decreases. At Yucca Mountain, the magnitude of the effect on water levels is on the order of centimeters. Earth tide fluctuations in Well UE-25pl are cited in non-YMP sources, and indicate a fluctuation of 2.05 cm (Bredehoeft 1987, p. 2460 [DIRS 10007]). This is corroborated by water levels in wells at Paiute Mesa, on the Nevada Test Site. These water levels were analyzed for earth tide effects and the fluctuation due to earth tides was on the order of several hundredths of a foot (Fenelon 2000, p. 14 [DIRS 160881]). Consequently, any individual fluctuation is of low magnitude. Additional corroboration is from Kies et al. ANL-WIS-MD-000019 REV 01 6-93 April 2004 (1999 [DIRS 160882]) who state, “tidal forces deform the earth; effects induced on fluids near the surface of the earth are documented by the observations of water level changes in wells. These changes are driven by alterations of the pore pressure induced by tidal deformation of porous and fluid-saturated crustal material.” These pressure changes can result in multiple related effects such as fluctuations in underground gas concentrations (Kies et al. 1999 [DIRS 160882]) and water level fluctuation in wells (Fenelon 2000, p. 14 [DIRS 160881]). As noted by Kies et al. (1999 [DIRS 160882]), the strain variations induced by earth tides are very small (less than on the order of 10-8), and their appearances are periodic and of known magnitude. Therefore, any significant cumulative effects of earth tides are reflected in the existing data for the hydrogeologic system (Assumption 5.3 of this analysis report). Earth tides are of such a small magnitude that any effect on the flow system is of low consequence because the fluctuations are accounted for within the water level data used as the basis for the TSPA. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Seismic activity changes porosity and permeability of rock (2.2.06.01.0A) Seismic activity changes porosity and permeability of fractures (2.2.06.02.0B) Seismic activity changes porosity and permeability of faults (2.2.06.03.0A) Hydrologic Response to Seismic Activity (1.2.10.01.0A) Supplemental Discussion: Table 6-27. Indirect Inputs for Earth Tides (1.5.03.02.0A) Reference Input Fenelon 2000, p. 14 [DIRS 160881] Water level fluctuations at Nevada Test Site Kies et al. 1999 [DIRS 160882] Magnitude of earth tide effects 6.2.4.9 Salt Creep (2.2.06.05.0A) FEP Description: Salt creep will lead to changes in the stress field, compaction of the waste packages, and consolidation of the long-term components of the sealing system. Descriptor Phrases: Geologic change (salt creep) Screening Decision: Excluded – By Regulation Screening Argument: “Salt creep” is excluded from the TSPA–LA based on regulatory requirements to consider data that are related to the geology of the site. Significant salt and evaporite deposits are not a feature of the geologic setting of the repository. ANL-WIS-MD-000019 REV 01 6-94 April 2004 The definition of geologic setting at 10 CFR 63.2 ([DIRS 156605]) is “the geologic, hydrologic, and geochemical systems of the region in which the geologic repository is or may be located.” Consideration of this FEP is outside the scope and intent stated at 10 CFR 63.21(c)(1) ([DIRS 156605]), which specifies consideration and description of “features, events, and processes outside of the site to the extent the information is relevant and material to safety or performance of the geologic repository.” Furthermore, at 10 CFR 63.114(a) and 10 CFR 63.115(a) ([DIRS 156605]), the regulatory requirements are to “include data that are related to the geology, hydrology, and geochemistry (including disruptive events) of the Yucca Mountain Site, and the surrounding region to the extent necessary …”. The regulation further requires the project to “identify … natural features of the geologic setting that are considered barriers important to waste isolation.” At 10 CFR 63.305(c) ([DIRS 156605]), DOE is directed to “…vary factors related to the geology, hydrology, and climate based upon cautious, but reasonable assumptions consistent with present knowledge of factors that could affect the Yucca Mountain disposal system over the next 10,000 years.” Evaporite deposits of sufficient volume to result in salt creep have not been reported near Yucca Mountain. Rather, Yucca Mountain is located in the southwestern Nevada volcanic field and consists of tilted fault blocks composed of layered sequences of ash flow, ash-fall, and bedded tuffs of Miocene age (BSC 2004, Section 6.5.1.4 and Table 4 [DIRS 168029]; as corroborated by Simmons 2004, Section 3.3.4 [DIRS 166960], and as shown by Day et al. 1998 [DIRS 100027]). Voluminous evaporite deposits do not exist in the vicinity of Yucca Mountain, and the repository is not planned for a salt dome or cavern. This feature and related process of salt creep are, therefore, inconsistent with the present knowledge of the geologic setting for Yucca Mountain. There are no rocks in the repository that are sufficiently plastic to creep in a manner similar to salt. Salt creep, therefore, is excluded based on regulations. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Diapirism (1.2.09.01.0A) Effects of subsidence (2.2.06.04.0A) Large-scale dissolution (1.2.09.02.0A) Salt diapirism and dissolution (1.2.09.00.0A) Supplemental Discussion: Table 6-28. Indirect Inputs for Salt Creep (2.2.06.05.0A) Reference Input Simmons 2004, Section 3.3.4 [DIRS 166960] Lithology at Yucca Mountain Day et al. 1998 [DIRS 100027] Geology at Yucca Mountain ANL-WIS-MD-000019 REV 01 6-95 April 2004 6.2.4.10 Effects of Repository Heat on the Biosphere (2.3.13.03.0A) FEP Description: This FEP addresses the heat released from radioactive decay of the waste that will increase the temperatures at the surface above the repository. This could result in local or extensive changes in ecological characteristics. Descriptor Phrases: Effects of repository heat on biosphere Screening Decision: Excluded – By Regulation and Low Consequence Screening Argument: “Effect of repository heat on the biosphere” is excluded from the TSPA–LA based on regulation and low consequence because the regulations preclude consideration of changes in flora and fauna and any such changes would likely have minimal impact on infiltration rates. The effects of repository heat on the biosphere are summarized in the FEIS (DOE 2002, Section 5.9 [DIRS 155970]) based on work by CRWMS M&O (1999, p. 46 [DIRS 105031]) and are chiefly related to concerns with transition from perennial to annual plant species. At 10 CFR 63.305(b) ([DIRS 156605]), the NRC states that: DOE should not project changes in society, the biosphere (other than climate), human biology, or increases or decreases of human knowledge or technology. In all the analyses done to demonstrate compliance with this part, DOE must assume that all of those factors remain constant as they are at the time of submission of the license application. The definition of reference biosphere at 10 CFR 63.2 ([DIRS 156605]) specifically identifies flora as being a component of the reference biosphere. Reference biosphere means the description of the environment inhabited by the reasonably maximally exposed individual. The reference biosphere comprises the set of specific biotic and abiotic characteristics of the environment, including, but not necessarily limited to, climate, topography, soils, flora, fauna, and human activities. By implication, DOE should not project changes in the biosphere (more specifically, flora) and must assume that the flora remain constant. Therefore, the effects of repository heat on the biosphere are excluded based on regulation. By way of corroboration, the DOE has presented the results of a study of the potential effects of repository heat on the biosphere in the FEIS (DOE 2002, p. 5-41 [DIRS 155970]) to satisfy non-NRC regulatory requirements. The effect of repository heat on the geosphere is addressed separately in the related FEP 2.2.10.12.0A (Geosphere dryout due to waste heat). The FEP description does not specify how a change in ecological factors might affect the performance of a repository located 200 m (656 feet) below ground surface. One feasible conceptual mechanism might be a change in infiltration due to a change in plant species. ANL-WIS-MD-000019 REV 01 6-96 April 2004 Changes in infiltration due to changes in ecological factors are expected to be insignificant in comparison to differences in infiltration resulting from use of the bounding infiltration cases resulting from changes in climate state, particularly if the ecological factor is primarily a shift in species rather than a shift in entire ecosystems. Additionally, the shift in species would be transient, and would potentially reverse as the repository cooled with time. This is corroborated by pre-1998 studies indicating that resulting temperature changes are within the adaptive range of some plant species now at Yucca Mountain (CRWMS M&O 1999, Figure 8 and p. 41 [DIRS 105031]). As indicated in BSC 2004 (Table 6.1-2, [DIRS 168027]), the range of average infiltration values considered is from 1.25 mm/year for the lower bound for present day climate to as much as 31.69 mm/year for the upper bound of the glacial transition climate. This represents an approximately 25 times increase between the lower bounding case and the upper bounding case incorporated into the TSPA-LA. For the various climate states considered, the mean infiltration rates range from 4.43 to 17.02 mm/year, or an approximate increase of four times. Climate change and its effects on infiltration are addressed in the TSPA-LA as outlined in Section 5.1 of the Total System Performance Assessment-License Application Methods and Approach (BSC 2003 [DIRS 166296]), and infiltration rates include consideration of upper-bound, mean, and lower-bound rates. This FEP is also excluded based on low consequence because the resulting change in infiltration rate is likely to be significantly less than the range in infiltration rates due to climate changes that are already considered. By way of corroboration, a potential effect of the repository heat is a shift in species at the surface. This shift in species could conceivably result in a change in water infiltration rate. However, change in water infiltration is potentially affected by a number of factors such as increases and decreases in vegetation and vegetation type, climate changes, slope, aspect, total precipitation, air temperature, runoff, solar heating, and characteristics of the soil matrix. The degree of the change in species due to change in temperature is discussed in Final Report: Plant and Soil Related Processes along a Natural Thermal Gradient at Yucca Mountain, Nevada (CRWMS M&O 1999 [DIRS 105031]) and is used as the basis for this corroborative argument and is as follows. The Executive Summary of the cited report states that during active transpiration periods, shrubs removed about 31 percent of the total precipitation that fell during the period studied (with a range of 12 to 54 percent at the seven study locations having a full range of plant species). Figure 9 of the same report indicates that total shrub coverage at the sites ranged from about 8 to 16 percent. In Section 3.3 of the cited report, an analysis of percent cover of shrubs and of soil temperature at a depth of 45 cm suggests that for each 1°C increase in temperature, the percent cover of shrubs decreases by 1.2 percent and that the percent cover of annual grasses increases 5.5 percent. The percent cover of the only grass species currently found at each of the study sites (Bromus rubens) increased by 2.3 percent with every 1ºC increase in temperature. Table 5-15 of the FEIS (DOE 2002, p. 5-41 [DIRS 155970]) presents the results of various analyses of the impact of the repository heat on the near-surface soil layer of the biosphere. These results predict that the soil temperature near the root zone of the shrub increases by a maximum of 0.4°C in wet soils and 3°C in dry soils. Further, they predict that at a soil depth of 2 m (7 feet), the soil temperature can increase by a maximum of 0.8°C in wet soils and 6°C in dry soils. Consequently, the temperature shift of concern can range between 0.4°C and 6°C. The resulting ANL-WIS-MD-000019 REV 01 6-97 April 2004 percent cover of shrubs could decrease by about 0.5 percent to 7.2 percent (i.e., 1.2 % change/°C, multiplied by the temperature change). Table 6-29, as part of this corroborative analysis, uses the preceding values to calculate the reduction in evapotranspiration, based on existing evapotranspiration and shrub coverage, and on thermally driven changes in shrub coverage. Table 6-29. Approximation of Percent Change in Evapotranspiration Due to Shift in Plant Species Percent Evapotranspiration from Shrubs (Range for Existing Conditions Percent Shrub Coverage (Existing) Percent Evapotranspiration Divided by Percent Shrub Coverage Change in Percent Shrub Coverage Approximate Change in Percent Evapotranspiration 12 (low) 8 1.5 0.5 0.8 31 (mean) 8 3.9 0.5 2.0 54 (high) 16 3.4 0.5 1.7 12 (low ) 8 1.5 7.2 11 31 (mean) 16 1.9 7.2 14 54 (high) 16 3.4 7.2 25 Table 6-29 uses the stated values to represent the range of evapotranspiration (12 to 54 percent) and dividing by the stated values for the range of existing coverage by shrubs (8 to 16 percent) yields a ratio for percent evapotranspiration to percent shrub coverage. Multiplying this ratio by the values of the percent change in coverage yields a percent change in evapotranspiration due to change in the shrub coverage. This suggests that a shift away from shrub species could result in a little less than 1 percent to at most a 25-percent decrease in transpiration of total precipitation, and the potential for a similar increase in infiltration, due to the loss of shrub cover. These values are conservative in that they do not account for an offsetting contribution to evapotranspiration from the increase in annual grass percentages (i.e., 2.3 percent increase in annual grasses for each 1°C in temperature). Additionally, the variation in surface soil temperatures at Yucca Mountain that are caused by elevation, slope, aspect, and other natural attributes suggest that soil temperature increases of the magnitude predicted are probably within the adaptive range of some plant species now at Yucca Mountain (CRWMS M&O 1999, Figure 8 and p. 41 [DIRS 105031]). Thus increases in infiltration would likely be less than those stated. TSPA Disposition: Not Applicable Related Documents: None Related FEPs: Non-uniform heat distribution in EBS (2.1.11.02.0A) Geosphere dry-out due to waste heat (2.2.10.12.0A) Heat generation in EBS (2.1.11.01.0A) ANL-WIS-MD-000019 REV 01 6-98 April 2004 Supplemental Discussion: Table 6-30. Indirect Inputs for Effects of Repository Heat on the Biosphere (2.3.13.03.0A) Reference Input DOE 2002, Section 5.9 [DIRS 155970] Results of FEIS analysis of heat effects CRWMS M&O (1999, p. 46 [DIRS 105031] Effects of heat on plant species DOE 2002, p. 5-41 [DIRS 155970] Potential effect of heat on the biosphere CRWMS M&O 1999, Figure 8 and p. 41 [DIRS 105031] Adaptive ranges of existing species BSC 2003, Section 5.1 [DIRS 166296] Method of modeling climate change for TSPA-LA CRWMS M&O 1999 [DIRS 105031] Reference to past plant surveys and estimated changes due to heat effects FEIS = final environmental impact statement, TSPA-LA = total system performance assessment for license application ANL-WIS-MD-000019 REV 01 6-99 April 2004 INTENTIONALLY LEFT BLANK ANL-WIS-MD-000019 REV 01 6-100 April 2004 7. CONCLUSIONS Table 7-1 summarizes the System Level FEP-screening decisions and the basis for Exclude decisions. Table 7-1. Summary of System Level FEP Screening Decisions FEP Name FEP Number Screening Decision and Basis Addressed in Section ASSESSMENT BASIS AND MODELING REQUIREMENTS FEPs (Section 6.2.1) Timescales of Concern (0.1.02.00.0A) Included 6.2.1.1 Spatial Domain of Concern (0.1.03.00.0A) Included 6.2.1.2 Regulatory Requirements and Exclusions (0.1.09.00.0A) Included 6.2.1.3 Model and Data Issues (0.1.10.00.0A) Included 6.2.1.4 Repository Design (1.1.07.00.0A) Included 6.2.1.5 Retrievability (1.1.13.00.0A) Included 6.2.1.6 Repository-Scale Spatial Heterogeneity of Emplaced Waste (2.1.01.04.0A) Included 6.2.1.7 PROCESS AND SITE-CONTROL FEPs (Section 6.2.2) Records and Markers for the Repository (1.1.05.00.0A) Excluded – By Regulation 6.2.2.1 Inadequate Quality Control and Deviations from Design (1.1.08.00.0A) Excluded – Low Consequence 6.2.2.2 Schedule and Planning (1.1.09.00.0A) Excluded – By Regulation 6.2.2.3 Administrative Control of the Repository Site (1.1.10.00.0A) Excluded – By Regulation 6.2.2.4 Monitoring of the Repository (1.1.11.00.0A) Excluded – Low Consequence 6.2.2.5 Accidents and Unplanned Events During Construction and Operation (1.1.12.01.0A) Excluded – Low Consequence 6.2.2.6 HUMAN INTRUSION FEPs (Section 6.2.3) Deliberate Human Intrusion (1.4.02.01.0A) Excluded – By Regulation 6.2.3.1 Inadvertent Human Intrusion (1.4.02.02.0A) Excluded – By Regulation 6.2.3.2 Igneous Event Precedes Human Intrusion (1.4.02.03.0A) Excluded – By Regulation 6.2.3.3 Seismic Event Precedes Human Intrusion (1.4.02.04.0A) Excluded – Low Consequence and By Regulation 6.2.3.4 Unintrusive Site Investigation (1.4.03.00.0A) Excluded – By Regulation 6.2.3.5 Drilling Activities (Human Intrusion) (1.4.04.00.0A) Excluded – By Regulation 6.2.3.6 Effects of Drilling Intrusion (1.4.04.01.0A) Excluded – By Regulation 6.2.3.7 Mining and Other Underground Activities (Human Intrusion) (1.4.05.00.0A) Excluded – By Regulation 6.2.3.8 Explosions and Crashes (Human Activities) (1.4.11.00.0A) Excluded – By Regulation and Low Consequence 6.2.3.9 Repository Excavation (3.3.06.01.0A) Excluded – By Regulation and Low Consequence 6.2.3.10 ANL-WIS-MD-000019 REV 01 7-1 April 2004 Table 7-1. Summary of System Level FEP Screening Decisions (Continued) FEP Name FEP Number Screening Decision and Basis Addressed in Section MISCELLANEOUS GEOLOGIC AND ASTRONOMIC FEPs (Section 6.2.4) Metamorphism (1.2.05.00.0A) Excluded – Low Probability and Low Consequence 6.2.4.1 Diagenesis (1.2.08.00.0A) Excluded – Low Consequence 6.2.4.2 Salt Diapirism and Dissolution (1.2.09.00.0A) Excluded – By Regulation 6.2.4.3 Diapirism (1.2.09.01.0A) Excluded – By Regulation 6.2.4.4 Meteorite Impact (1.5.01.01.0A) Excluded – Low Probability and Low Consequence 6.2.4.5 Extraterrestrial Events (1.5.01.02.0A) Excluded – Low Consequence 6.2.4.6 Changes in the Earth's Magnetic Field (1.5.03.01.0A) Excluded – Low Consequence 6.2.4.7 Earth Tides (1.5.03.02.0A) Excluded – Low Consequence 6.2.4.8 Salt Creep (2.2.06.05.0A) Excluded – By Regulation 6.2.4.9 Effects of Repository Heat on the Biosphere (2.3.13.03.0A) Excluded – By Regulation and Low Consequence 6.2.4.10 FEPs = features, events, and processes The conclusions from this document (FEP screening decisions and supporting rationale) are considered “technical product output” with no assigned DTN. The saturated zone FEP screening decision, TSPA-LA disposition (for included FEPs), or screening argument (for excluded FEPs), will be incorporated in the Yucca Mountain TSPA-LA FEP database. This database will contain all Yucca Mountain FEPs considered for TSPA-LA with FEP Number, Name, Description, and relevant FEP AMRs where specific FEPs are screened. The FEP database will also contain Descriptor Phrases, Screening Decisions (Include or Exclude), Screening Arguments, and TSPA Dispositions quoted from this and all other FEP AMRs. Documentation of the FEP database will be given in a separate AP-3.11Q report. All FEP information, including the 33 System Level FEPs considered in this report, will be submitted to Technical Data Management System by the Yucca Mountain FEP database team as a final LA FEP DTN. These final data will be qualified as Technical Product Output from the AP-3.11Q report. The final FEP DTN will supersede all of the previous DTNs. 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"Morphology, Age, and Rate of Accumulation of Pedogneic CaCO3 in Some Calcareous Soils and Pedogenic Calcrete of Southwestern United States." GSA Abstracts with Programs, 14, (4), . Boulder, Colorado: Geological Society of America. 167815 Lattman, L.H. 1983. "Effect of Caliche on Desert Processes." Chapter 4 of Origin and Evolution of Deserts. Wells, S.G. and Haragan, D.R.; eds. 1st Edition. Albuequerque, New Mexico: University of New Mexico Press. TIC: 255700. ANL-WIS-MD-000019 REV 01 8-12 April 2004 167869 Salem, A.M.K.; Abdel-Wahab, A.; and McBride, E.F. 1998. "Diagenesis of Shallowly Buried Cratonic Sandstones, Southwest Sinai, Egypt." Sedimentary Geology, 119, ([3-4]), 311-335. [New York, New York]: Elsevier. TIC: 255708. 167870 Retallack, G. J. 1991. "Untangling the Effects of Burial Alteration and Ancient Soil Formation." Annual Review of Earth and Planetary Sciences. Weatherhill, G.. Vol. 19, 183-206. Palo Alto, California: Annual Reviews Inc. TIC: 255912. 167871 Baldwin, B. and Butler, C. O. 1985. "Compaction Curve." American Association of Petroleum Geologists Bulletin, 69, (4), 622-626. Tulsa, Oklahoma: American Association of Petroleum Geologists. TIC: 255917. 167872 Karam, P. A. 2002. "Gamma and Neutrino Radiation Dose from Gamma Ray Bursts and Nearby Supernovae." Health Physics, 82, (4), 491-499. Baltimore, Maryland: Lippincott, Williams, and Wilkins. TIC: 255918. 167873 Brakenridge, G.R. 1981. "Terrestrial Paleoenvironmental Effects of a Late Quaternary-Age Supernova." Icarus, 46, ([1]), 81-93. [New York, New York]: Academic Press. TIC: 255707. 167875 Ruderman, M. A. 1974. "Possible Consequences of Nearby Supernova Explosions for Atmospheric Ozone and Terrestrial Life." Science, 184, (4141), 1079-1081. [Washington, D.C : American Association for the Advancement of Science]. TIC: 255914 167876 Biggin, A.J. and Thomas, D.N. 2003. "Analysis of Long-Term Variations in the Geomagnetic Polodial Field Intensity and Evaluation of Their Relationship with Global Geodynamics." Geophysical Journal International, 152, ([2]), 392-415. [Oxford, England: Blackwell Publishing]. TIC: 255680. 167952 Satchwell, R.M. 1994. An Experimental Study of the Effect of Bedding Plane Anisotrophy on the Rate of Penetration. Ph.D. dissertation. Laramie, Wyoming: University of Wyoming, Department of Chemical and Petroleum Engineering. TIC: 255659. 167965 Press, F. and Siever, R. 1978. Earth. 2nd Edition. Chapters 11 and 16.San Francisco, California: W. H. Freeman and Company. TIC: 255856. 168024 BSC (Bechtel SAIC Company) 2004. Technical Work Plan for: Decision Support and Documentation Department Activities. TWP-MGR-MD-000028 REV 04. Las Vegas, Nevada: Bechtel SAIC Company. ACC: DOC.20040303.0003. 168027 BSC (Bechtel SAIC Company) 2004. UZ Flow Models and Submodels. MDL-NBS- HS-000006 REV 01 ERRATA 1. Las Vegas, Nevada: Bechtel SAIC Company. ACC: DOC.20030818.0002; DOC.20040211.0008. ANL-WIS-MD-000019 REV 01 8-13 April 2004 168029 BSC (Bechtel SAIC Company) 2004. Geologic Framework Model (GFM2000). MDL-NBS-GS-000002 REV 01 ERRATA 1. Las Vegas, Nevada: Bechtel SAIC Company. ACC: MOL.20020530.0078; DOC.20040128.0007; DOC.20040211.0003. 168030 BSC (Bechtel SAIC Company) 2004. Characterize Framework for Seismicity and Structural Deformation at Yucca Mountain, Nevada. ANL-CRW-GS-000003 REV 00. ERRATA 1 Las Vegas, Nevada: Bechtel SAIC Company. ACC: MOL.20000510.0175; DOC.20040223.0007. 8.2 CODES, STANDARDS, REGULATIONS, AND PROCEDURES 155216 66 FR 32074. 40 CFR Part 197, Public Health and Environmental Radiation Protection Standards for Yucca Mountain, NV; Final Rule. Readily available. 156605 10 CFR 63. Energy: Disposal of High-Level Radioactive Wastes in a Geologic Repository at Yucca Mountain, Nevada. Readily available. 156671 66 FR 55732. Disposal of High-Level Radioactive Wastes in a Proposed Geologic Repository at Yucca Mountain, NV. Final Rule 10 CFR Part 63. Readily available. 165519 40 CFR 197. Protection of Environment: Public Health and Environmental Radiation Protection Standards for Yucca Mountain, Nevada. Readily available 164073 AP-3.15Q, Rev. 4, ICN 3. Managing Technical Product Inputs. 164786 AP-2.22Q, Rev. 1, ICN 0. Classification Analyses and Maintenance of the Q-List. 166252 AP-SIII.9Q, Rev. 1, ICN 3. Scientific Analyses. 168412 LP-SI.11Q-BSC, Rev. 0, ICN 0. Software Management. 8.3 SOURCE DATA, LISTED BY DATA TRACKING NUMBER 148850 MO0003RIB00071.000. Physical and Chemical Characteristics of Alloy 22. Submittal date: 03/13/2000. 152554 MO0004QGFMPICK.000. Lithostratigraphic Contacts from MO9811MWDGFM03.000 to be Qualified Under the Data Qualification Plan, TDP NBS-GS-000001. Submittal date: 04/04/2000. 152926 MO0003RIB00073.000. Physical and Chemical Characteristics of Ti Grades 7 and 16. Submittal date: 03/13/2000. 153044 MO0003RIB00076.000. Physical and Chemical Characteristics of Type 316N Grade. Submittal date: 03/14/2000. 167431 MO0307SEPFEPS4.000. LA FEP List. Submittal date: 12/01/2003. 166073 MO0311RCKPRPCS.003. Intact Rock Properties Data on Uniaxial and Triaxial Compressive Strength. Submittal date: 11/04/2003. ANL-WIS-MD-000019 REV 01 8-14 April 2004 ATTACHMENT I GLOSSARY ANL-WIS-MD-000019 REV 01 April 2004 ATTACHMENT I GLOSSARY alluvial fan A cone-shaped deposit of alluvium made by a stream where it runs out onto a level plain or meets a slower stream. The fans generally form where streams issue from mountains upon the lowland. annual exceedance probability The probability that a specified value (such as ground motion or fault displacement) will be exceeded during one year. astronomical unit (AU) A measure for distance within the solar system equal to the mean distance between earth and sun, that is, about 92,956,000 miles [149,598,000 km]. asteroid A small planet with a diameter from a fraction of a mile to nearly 500 miles. bolide A meteor that show signs of explosion or fragmentation. caliche A calcareous soil component typically forming a friable to hard, off- white, crudely layered interval near the surface of stony desert soils; several cm or more thick; old, thick caliche intervals (calcrete) have the texture and hardness of concrete aggregate. colluvial slope A hill slope mantled with loose, heterogeneous soil and rock fragments that are the result of weathering and accumulation by creep and unchanneled snowmelt or runoff. comet A celestial body that consists of a fuzzy head usually surrounding a bright nucleus, that often, with the part of its orbit near the sun, develops a long tail which points away from the sun and that has an orbit varying in eccentricity between nearly round and parabolic. diagenesis Processes involving physical and chemical changes in sediment after deposition that convert it to consolidated rock; includes compaction, cementation, recrystallization, and perhaps replacement. diapir A dome or anticlinal fold, the overlying rocks of which have been ruptured by squeezing out of the plastic core material. Diapirs in sedimentary strata usually contain cores of salt or shale. Igneous intrusions may also show diapiric structure. dike A tabular intrusion of magma that is at a high angle to layering in the intruded strata (i.e., vertical or subvertical at Yucca Mountain). ANL-WIS-MD-000019 REV 01 I-1 April 2004 disruptive FEP An Included FEP that has a probability of occurrence during the period of performance less than 1.0 (but greater than the cutoff of 10-4/104year). disruptive event The scenario class, or set of related scenarios classes, that describes scenario classes the behavior of the system if perturbed by disruptive events. The disruptive scenario classes contain all disruptive FEPs that have been retained for analysis. event A natural or anthropogenic phenomenon that has a potential to affect disposal system performance and that occurs during an interval that is short compared to the period of performance. excluded FEP A FEP that is identified by the FEP-screening process as requiring no further analysis in the quantitative TSPA, based on low probability, low consequence, or regulation. expected FEP An Included FEP that, for the purposes of the TSPA, is assumed to occur with a probability equal to 1.0 during the period of performance. faulting Process of fracture and attendant slip along the fracture plane, or recurrent slip along a such a plane. feature An object, structure, or condition that has a potential to affect disposal system performance. fireball A bright meteor with luminosity that equals or exceeds that of the brightest planets (generally magnitude –3 or brighter). folding Formation of folds expressed by geometric features that include fold limbs, fold axes, and axial planes. Large or systematic compressive and drag folds are results of tectonic activity. fracture A brittle crack in rock. Groups of fractures in more or less regular orientation and spacing are joints. Fractures form by bending (shear joints) or tension or principal stress reduction (extension joints). Cooling joints are formed by tension exerted by contraction as a volcanic rock cools. future A single, deterministic representation of the future state of the system. An essentially infinite set of futures can be imagined for any system. ANL-WIS-MD-000019 REV 01 I-2 April 2004 gamma ray burst geodetic strain rate graben gray igneous activity included FEP intrusive event (with respect to repository performance) meteor meteorite meteoroid metamorphism A burst of gamma-rays from space lasting from a fraction of a second to many minutes. There is no clear scientific consensus as to their cause or even their distance. Regional strain rate determined at the earth’s surface by repeated measurement of displacements of precisely located landmarks (monuments) embedded in the deforming medium. A block, generally long compared to its width that has been downthrown along faults relative to the rocks on either side. A unit of radiation dose equal to 1 joule of energy deposited in 1 kg of tissue or other material. The gray (Gy) is an SI unit and is equal to 100 rad. Any process associated with the generation, movement, emplacement, or cooling of molten rock within the earth or exterior to the earth’s surface. A FEP that is identified by the FEP-screening process as requiring analysis in the quantitative TSPA. An igneous intrusion (such as a dike, dike system, or other magmatic body in the subsurface) that intersects the repository footprint at the repository elevation. One of the small particles of matter in the solar system observable directly only when it falls into the earth’s atmosphere where friction may cause its temporary incandescence. A meteor that reaches the surface of the earth without being completely vaporized. A meteor particle itself without relation to the phenomena it produces when entering the earth’s atmosphere. Process by which consolidated rocks are altered in composition and texture, or internal structure, by conditions and forces not resulting simply from burial and weight of subsequently accumulated overburden. Pressure, heat, and the introduction of new chemical substances are the principal causes, and the resulting changes, which generally include the development of new minerals, are a thermodynamic response to a greatly altered environment. Diagenesis has been considered to be incipient metamorphism. ANL-WIS-MD-000019 REV 01 I-3 April 2004 modeling case nominal scenario class nonwelded unit paleoseismic slip potentiometric surface process radionuclide scenario class seismic activity A well-defined, connected sequence of FEPs that can be thought of as an outline of a future condition of the repository system. Modeling cases can be undisturbed, in which case the performance would be the expected, or nominal, behavior for the system. Modeling cases can also be disturbed, if altered by disruptive events such as human intrusion or natural phenomena such as volcanism, seismicity, or nuclear criticality. The scenario class, or set of related scenario classes, that describes the expected or nominal behavior of the system as perturbed only by the presence of the repository. The nominal scenario class contains all expected FEPs that have been retained for analysis. A volcanic ash, or tuff, that is crumbly or easily excavated because the component glass shards did not weld together during compaction of relatively cool ash, or ash having relatively sparse glass content. The amount of fault slip indicated by buried offset strata. Individual paleoearthquakes are indicated by discrete amounts of offset. A notional surface representing the total head of groundwater as defined by the level at which such water stands in a well. The water table is a particular potentiometric surface. A natural or anthropogenic phenomenon that has a potential to affect disposal system performance and that operates during all or a significant part of the period of performance. Radioactive type of atom with an unstable nucleus that spontaneously decays, usually emitting ionizing radiation in the process. Radioactive elements are characterized by their atomic mass and atomic number. A set of related modeling cases that share sufficient similarities that they can usefully be aggregated for the purposes of screening or analysis. The number and breadth of scenario classes depends on the resolution at which modeling cases have been defined. Coarsely defined modeling cases result in fewer, broad scenario classes, whereas narrowly defined modeling cases result in many narrow scenario classes. Scenario classes (and modeling cases) should be aggregated at the coarsest level at which a technically sound argument can be made, while still maintaining adequate detail for the purposes of analysis. Seismicity; the recurrence and distribution of earthquakes associated with a specified seismic source. ANL-WIS-MD-000019 REV 01 I-4 April 2004 strain rate The rate at which a unit of length is shortened or lengthened under a stress load, usually given in terms of inverse seconds. Strain rate is often expressed in units of mm/yr where an actual length difference, rather than a ratio, is calculated. stylized analysis An analysis using specified assumptions and requirements in lieu of speculation on the nature and probability of a subject event. supernova A stellar explosion that takes place late in the life of a massive star. tectonic activity The dynamic manifestation of stress loads generated within the earth’s crust (e.g., igneous intrusion, earthquakes, uplift). tectonic deformation The suite of geological structures generated by body stresses exerted within the earth’s crust; such structures range in scale from microscopic (e.g., mylonite fabric) to regional (e.g., overthrust belts). Also, the process by which such structures together are formed. tectonic extension Stretching or extension of the crust as a result of deep-seated tectonic stress, such as back-arc spreading. tectonic process The dynamic evolution of structure generated through the buildup and relaxation of regional stress. tectonism All movement of the crust at small scale produced by tectonic processes, including mountain building (orogeny), regional uplift, and subsidence; the general expression of tectonic processes through time and space. water table The surface of unconfined groundwater at which the pressure is equal to that of the atmosphere. welded unit A volcanic ash, or tuff, that is strongly indurated because hot glass shards partially melted together (welded) during compaction of the ash bed while the ash was still hot. ANL-WIS-MD-000019 REV 01 I-5 April 2004 INTENTIONALLY LEFT BLANK ANL-WIS-MD-000019 REV 01 I-6 April 2004 ATTACHMENT II SUITABILITY DEMONSTRATION FOR DATA FROM OUTSIDE SOURCES USED AS DIRECT INPUTS TO SYSTEM LEVEL FEPS ANL-WIS-MD-000019 REV 01 April 2004 ATTACHMENT II SUITABILITY DEMONSTRATION FOR DATA FROM OUTSIDE SOURCES USED AS DIRECT INPUTS TO SYSTEM LEVEL FEPS This attachment demonstrates the suitability of previously unqualified data for use in Section 6.2 and Attachments II and IV of this analysis report. It documents the data suitability demonstration as required for an analysis report prepared in accordance with AP-SIII.9Q, Scientific Analyses. It is not intended as stand-alone documentation separate from the main document. The data justified herein is intended for use only for features, events, and processes (FEPs) screening and, more specifically, for use within this work product. The System Level FEPs analyses require the use of input, cited from journal papers, compendiums, proceedings, Internet citations, and other non-Yucca Mountain Project (YMP) originated sources, to represent the nature, magnitude, and potential consequence of the System Level FEPs. The use and classification of such input is subject to classification per AP-3.15Q, Managing Technical Product Inputs, Attachment 3, because the information satisfies the definition of “direct input.” This non-project generated information directly used in the analysis is referred to as data because it is the “results of activities such as sample collection, physical measurements, testing, and analysis, both in the field and in the laboratory, that are not site- specific and do not meet the definition of Established Fact.” Per AP-SIII.9Q, data obtained from outside sources that are not established facts must be demonstrated to be suitable for the specific application. When appropriately justified, these data are considered as qualified for use within the technical product. The following factors are used to present the case that the data are suitable for intended use: • Reliability of data source . as noted by the type of publication and associated review • Extent to which the data demonstrate the properties of interest • Prior use of the data • Availability of corroborating data. Section 1 of this attachment identifies the direct inputs, Section 2 addresses the methods used to demonstrate suitability, and Section 3 discusses the appropriate criteria. Accordingly, Section 4 provides the evaluation of the data, and contains the discussion wherein the direct inputs are corroborated and shown suitable for use. 1. DATA SETS FOR USE WITHIN THIS TECHNICAL PRODUCT The direct inputs being evaluated are identified in Table II-1. The table has been subdivided by FEP or FEP grouping, which will be treated separately within Section 4 of this attachment. Each item in the following table has been assigned an Item designator (Q) to facilitate traceability to the sources and factors tables that appear in Section 4 of this Attachment. The tables in Section 4 of this attachment also address the corroborating information in tables presented in Section 4. Corroborating information has been identified in those tables with an Item designator (C), denoting that the item is being used for corroboration. ANL-WIS-MD-000019 REV 01 II-1 April 2004 The Source column in Table II-1 below provides the citation as it appears in the Document Input Reference System (DIRS) and provides traceability through the Technical Information Center (TIC) number and/or DIRS numbers. The Description column in the Table II-1 provides a brief description of the data being evaluated, by equation number, numeric value, or statement of the concept being used as the direct input. The direct input used in formulating a screening decision is listed along with the originating citation or information is given in normal type immediately below the input. This information is repeated in the last column in the tables in Sections 4. The citations provided in the Table II-1 also appear within Table 4-5 of the main body of the report. The tables in Section 4 of the main body identify the associated sections of the main body of the report that utilize the input, so that information is not repeated here. ANL-WIS-MD-000019 REV 01 II-2 April 2004 Table II-1. Data Sets for Use within This Technical Product Item Source Description of Direct Input Timing of Human Intrusion Analysis Q1 Bourgoyne, A.T., Jr.; Millheim, K.K.; Chenevert, M.E.; and Young, F.S., Jr. 1986. "Rotary Drilling Bits." Applied Drilling Engineering. [SPE Textbook Series Volume 2]. Pages 190-245. Richardson, Texas: Society of Petroleum Engineers. TIC: 250085. [DIRS 155223] The rate of drill penetration may range from inversely proportional to the square of the compressive strength to inversely proportional to the compressive strength of the rock. Equation 5-19 directly relates the square of the formation compressive strength to the rate of penetration and therefore allows a comparison of drilling behavior based on material properties. Q2* Kahraman, S.; Balci, C.; Yazici, S.; and Bilgin, N. 2000. "Prediction of the Penetration Rate of Rotary Blast Hole Drills Using a New Drillability Index." International Journal of Rock Mechanics and Mining Sciences, 37, ([5]), 729743. [New York, New York]: Pergamon. TIC: 255709. [DIRS 167761] The rate of drill penetration may range from inversely proportional to the square of the compressive strength to inversely proportional. Equation 8 addresses the rate of penetration in terms of a drillability index, but provides a correlation of the index to unconfined compressive strength and to tensile strength in Equations 14 and 15. Explosions and Crashes Q3 Backman, M.E. and Goldsmith, W. 1978. "The Mechanics of Penetration of Projectiles into Targets." International Journal of Engineering Science, 16, (1), 1-99. New York, New York: Pergamon. TIC: 255605. [DIRS 167628] The maximum penetration depth of earth penetrating weapons is approximately 30m. The relationships and equations giving depth of penetration are taken from p. 32, which provides information for a monobloc round-ended steel projectile with a length-to-diameter ratio of 8, striking normally at 150 m/s. The stated relationship is a penetration depth into sand of 350 diameters, and for high-strength concrete (5,000 psi strength), a penetration depth of 25 diameters. A maximum penetration depth can be calculated by assuming a penetrator with a maximum diameter. The Poncelet equation (Equation 6.2 on p. 38) and factors from Table 2 for hard soils (95 percent sand and, 5 percent silt a8 = 15.7, a10 = 24.7) are provided and can be used to determine a maximum penetration depth. A maximum depth can be determined by assuming the mass associated with the penetrator with a maximum diameter. Q4 Dence, M.R.; Grieve, R.A.F.; and Robertson, P.B. 1977. "Terrestrial Impact Structures: Principal Characteristics and Energy Considerations." Impact and Explosion Cratering, Planetary and Terrestrial Implications, Proceedings of the Symposium on Planetary Cratering Mechanics, Flagstaff, Arizona, September 13-17, 1976. Roddy, D.J.; Pepin, R.O.; and Merrill, R.B., eds. Pages 247-275. New York, New York: Pergamon Press. TIC: 247237. [DIRS 135253] The energy release required to create a crater with a diameter sufficient to fracture to 60 m or 200 m (i.e., the depths of interest) are on the order of 1012 to 1017 Joule. Figure 12 is used to relate energy release to crater diameter and hence to fracturing and cratering depth. The energy release from underground nuclear detonations results in fracturing to distances on the order of 100 meters or less. p. 262 indicates that the 64-kt Pile Driver test produced stresses at about 100 meters (328 feet) that were slightly less than those needed to propagate fractures in granodiorite. ANL-WIS-MD-000019 REV 01 II-3 April 2004 Table II-1. Data Sets for Use within This Technical Product (Continued) Item Source Description of Direct Input Explosions and Crashes (Continued) Q5 Ferguson, C.D. 2002. "Mini-Nuclear Weapons and the U.S. Nuclear Posture Review." Monterey, California: Monterey Institute of International Studies, Center for Nonproliferation Studies. Accessed December 4, 2002. TIC: 253717. http://www.cns.miis.edu/pubs/week/020 408.htm [DIRS 160988] The energy yield of conventional weapons is on the order of 2 tons or less. This is based on direct input from this citation stating that an explosive capability of 2 tons is given for the GBU-28 explosive ordnance. Q6 Forrestal, M.J.; Longcope, D.B.; and Norwood, F.R. 1981. "A Model to Estimate Forces on Conical Penetrators Into Dry Porous Rock." Journal of Applied Mechanics, 48, (1), 25-29. New York, New York: American Society of Mechanical Engineers. TIC: 255607. [DIRS 167630] The maximum penetration depth of earth penetrating weapons is approximately 30 m. Direct input from this paper indicate that experimental test results at the Sandia, Tonopah Test Range, Nevada indicate a penetrator; 1.52 m long, with outer diameter of 0.165 m and mass of 182 kg, with an initial velocity of 411 m/s penetrated to a depth of 2.6 m. in unsaturated welded tuff Q7 Patterson, W.J. 1974. "Results and Analysis of Three Instrumented Projectile Penetration Tests at the Watching Hills Blast Range, Suffield, Alberta, Canada." EOS, Transactions, 56, (12), 1197. Washington, D.C.: American Geophysical Union. TIC: 255677. [DIRS 167805} The maximum penetration depth of earth penetrating weapons is approximately 30 m Provides empirical information on rock penetrations tests. Penetrators with a diameter of 15.24 cm and mass of 181.4 kg were fired with impact velocities of 93 m/sec, 122.8 m/s and 150.9 m/sec and achieved penetration depths of 9.08 m, 14.7 m, and 20.7 m respectively. The target material was an old glacial lake bed. Q8 Stix, G. and Yam, P. 2001. "Facing a New Menace." Scientific American, 285, (5), 14-15. [New York, New York]: Scientific American. TIC: 254304. [DIRS 160994] Kinetic energy for jet aircraft is approximately 2 tons TNT equivalent or less This information provides energy release associated with a large jetliner (Boeing 767) crash. Q9 Young, C.W., 1976. Status Report on High Velocity Soil Penetration Program. SAND76-0291. Albuquerque, New Mexico: Sandia National Laboratories. [DIRS 167806] The maximum penetration depth of earth penetrating weapons is approximately 30 m. Provides empirical information on soil penetration tests, Table II indicates that a penetrator with a weight of 320 lbs, and 6.0 inch diameter impacting with a speed of 2316 feet per second penetrated 220.5 feet (67 m) into a dry playa soil. ANL-WIS-MD-000019 REV 01 II-4 April 2004 Table II-1. Data Sets for Use within This Technical Product (Continued) Item Source Description of Direct Input Metamorphism Q10 Ehlers, E.G. and Blatt, H. 1982. Petrology, Igneous, Sedimentary, and Metamorphic. New York, New York: W.H. Freeman and Company. TIC: 255657. [DIRS 167802] The minimum conditions needed for onset of metamorphism are: T> 150-200ºC P = 0.5-1 kbar Depth = 4-5 km The range in geothermal gradients is 10 to 25ºC and the pressure gradient is approximately 0.6 kbar/km From p. 566, the text states “the minimum temperature at which typical regional metamorphic processes begin in sediments is about 150 – 200 degrees C, with pressures on the order of 0.5-1 kbar and depth within the crust of about 4-5 km. At these pressures and temperatures diagenetic processes are complete.” From p. 684-685, the range in geothermal gradients at convergent plate junctions is inferred typically to be between 10 and 25 degrees C/km. From p 168, Figure 6-3, in the top 200 km of the crust, the pressure gradient is approximately 1 mbar per 1500 km (or about 0.6 kbar per km) and the temperature gradient is approximately 1000 degrees C per 100 kilometer or 10 degrees per kilometer. Diagenesis Q11 Krystinik, L.F. 1990. "Early Diagenesis in Continental Eolian Deposits." Chapter 8 of Modern and Ancient Eolian Deposits: Petroleum Exploration and Production. Fryberger, S.G.; Krystinik, L.F.; and Schenk, C.J., eds. Denver, Colorado: Society of Economic Paleontologists and Mineralogists, Rocky Mountain Section. TIC: 247781. [DIRS 135295] The time required for diagenesis is less than 10,000 years p. 8-1 indicates that shallow diagenesis may be achieve lithification within 5,000 years Compaction does not generally become significant until deep burial has occurred pp. 8-2 and 8-3 indicate that initial compaction can reduce porosity by 20-30 percent, but additional compaction is not significant prior to deep burial. Cements other than carbonate may develop in arid environments p. 8-4 indicates that iron, aluminum, and silica may be cementing agents in arid environments. Q12 Lattman, L.H. and Simonberg, E.M. 1971. "Case-Hardening of Carbonate Alluvium and Colluvium, Spring Mountains, Nevada." Journal of Sedimentary Petrology, 41, (1), 274281. [Tulsa, Oklahoma: Society of Economic Paleontologists and Mineralogists]. TIC: 223189. [DIRS 129306] The time required for diagenesis is less than 10,000 years p. 277 provides a bound on the rate of case-hardening and formation of calcretes in southeastern Nevada and suggests rates on the order of tens of years. Q13 Lattman, L.H. 1973. "Calcium Carbonate Cementation of Alluvial Fans in Southern Nevada." Geological Society of America Bulletin, 84, (9), 3013-3028. Boulder, Colorado: Geological Society of America. TIC: 235904. [DIRS 129305] Cementation by CaCO3 is not a significant process in rhyolitic tuffs. p. 3015 of this paper discusses the role of carbonate cements for rhyolitic tuffs and indicates that carbonate cementation is not significant if a source of carbonate is not present. ANL-WIS-MD-000019 REV 01 II-5 April 2004 Table II-1. Data Sets for Use within This Technical Product (Continued) Item Source Description of Direct Input Diagenesis (Continued) Q14 Reeves, C.C. 1976. Caliche: Origin, Classification, Morphology and Uses. Lubbock, Texas: Estacado Books. TIC: 245928. [DIRS 104303] The net effect of cementation is to decrease infiltration rates p. 110 indicates that a caliche horizon impedes the movement of both infiltration and capillary water and cites several supporting studies. Q15 Taylor, E.M. 1986. Impact of Time and Climate on Quaternary Soils in the Yucca Mountain Area of the Nevada Test Site. Master's thesis. [Boulder, Colorado]: University of Colorado. TIC: 218287. [DIRS 102864] p. 86 SiO2 cementation is not dependent on climatic conditions, but does exhibit distinctive trends that correspond with the ages of the surficial deposits. p. 87 Accumulation rates are attributable to several climatic scenarios, but changes were insufficient to decrease the rate of accumulation p. 89 Modeling suggest that CaCO3 may translocate to greater depth with onset of greater precipitation The preceding statements are taken from Chapter 5 of the citation. p. 33, Figure 9, accumulation rates for Yucca Mountain favor SiO2 over CaCO3, which is an accessory cement, and the cementation process is reversible. The preceding statements are taken from pp. 31-33, Figure 9, pp 86 to 89, and Chapter 5 of the citation. Meteorite Impact Q16 Ceplecha, Z. 1992. "Influx of Interplanetary Bodies onto Earth." Astronomy and Astrophysics, 263, 361366. New York, New York: Springer- Verlag. TIC: 246784. [DIRS 135242] Source of flux information for full range of masses p. 362 and Figure 1 Q17 Ceplecha, Z. 1994. "Impacts of Meteoroids Larger than 1m into the Earth's Atmosphere." Astronomy and Astrophysics, 286, (3), 967-970. New York, New York: Springer-Verlag. TIC: 246761. [DIRS 135243] Source of flux data based on percent composition and related densities. p. 967-969, Tables 1, 3, 4, Figure 2 Q18 Dence, M.R.; Grieve, R.A.F.; and Robertson, P.B. 1977. "Terrestrial Impact Structures: Principal Characteristics and Energy Considerations." Impact and Explosion Cratering, Planetary and Terrestrial Implications, Proceedings of the Symposium on Planetary Cratering Mechanics, Flagstaff, Arizona, September 13-17, 1976. Roddy, D.J.; Pepin, R.O.; and Merrill, R.B., eds. Pages 247-275. New York, New York: Pergamon Press. TIC: 247237. [DIRS 135253] Energy to crater diameter and cratering depth relationships. p. 250, pp. 261-264 ANL-WIS-MD-000019 REV 01 II-6 April 2004 Table II-1. Data Sets for Use within This Technical Product (Continued) Item Source Description of Direct Input Meteorite Impact (continued) Q19 Grieve, R.F. 1987. "Terrestrial Impact Structures." Annual Review of Earth and Planetary Sciences, 15, 245-269. Palo Alto, California: Annual Reviews. TIC: 246788. [DIRS 135254] Cratering rate distribution based on observed earth cratering (i.e., proportional to Dcrater -1.8) and threshold size for onset of complex cratering (4km). p. 248, p. 257. Figure 8 Q20* Grieve, R.; Rupert, J.; and Therriault, A. 1995. "The Record of Terrestrial Impact Cratering." GSA Today, 5, (10), 194196. Boulder, Colorado: Geological Society of America. TIC: 246688. [DIRS 135260]. Onset of complex cratering is with crater diameters is 4 km. p. 194 Q21* Grieve, R.A.F. 1998. "Extraterrestrial Impacts on Earth: The Evidence and the Consequences." Meteorites: Flux with Time and Impact Effects. Grady, M.M.; Hutchinson, R.; McCall, G.J.H.; and Rothery, D.A., eds. Geological Society Special Publication No. 140. Pages 105-131. London, England: Geological Society. TIC: 254143. [DIRS 163385] Crater diameter to depth of effect relationships. Depth of exhumation is approximately 0.28 Dcrater. p. 113, Figure 8. Q22 Hills, J.G. and Goda, P.M. 1993. "Fragmentation of Small Asteroids in the Atmosphere." The Astronomical Journal, 105, (3), 1114-1144. Woodbury, New York: American Institute of Physics. TIC: 246798. [DIRS 135281]. Modeling results demonstrating of a variety of effects from meteorite impact including resulting crater diameters and related consequences. Figures 16 and 17 provide key meteor radius to crater diameter relationship information. Q23 Shoemaker, E.M. 1983. "Asteroid and Comet Bombardment of the Earth." Annual Review of Earth and Planetary Sciences, 11, 461-494. Palo Alto, California: Annual Reviews. TIC: 246922. [DIRS 135308]. Contribution of iron meteors to the total flux is about 5 percent pp. 464 and 480 Q24 Wuschke, D.M.; Whitaker, H.H.; Goodwin, B.W.; and Rasmussen, L.R. 1995. Assessment of the Long-Term Risk of a Meteorite Impact on Hypothetical Canadian Nuclear Fuel Waste Disposal Vault Deep in Plutonic Rock. AECL-11014. Pinawa, Manitoba, Canada: Atomic Energy of Canada Limited, Whiteshell Laboratories. TIC: 221413. [DIRS 129326]. Spatial relationships of crater diameter to extents and depth of fracturing (0.76 Dcrater) and exhumation (0.14 Dcrater) pp. 3 Spatial extent of fracturing is assumed to be spherical Figure 1. Cratering rate data for the Canadian shield and application to a hypothetical Canadian repository pp. 4 and 26 ANL-WIS-MD-000019 REV 01 II-7 April 2004 Table II-1. Data Sets for Use within This Technical Product (Continued) Item Source Description of Direct Input Extraterrestrial Events Q25 Brakenridge, G.R. 1981. "Terrestrial Paleoenvironmental Effects of a Late Quaternary-Age Supernova." Icarus, 46, ([1]), 81-93. [New York, New York]: Academic Press. TIC: 255707. [DIRS 167873] Frequency of supernova event (1 event per 100 years), magnitude (1050 ergs), and potential consequences of the event (nitrogen enrichments, ozone depletion, global cooling) due to a supernova event. p. 81-93 Q26* Lean, J. 1997. "The Sun's Variable Radiation and its Relevance for Earth." Annual Review of Astronomy and Astrophysics, 35, 33-67. [Palo Alto, California: Annual Reviews]. TIC: 255614. [DIRS 167639] Relationship exist between the decadal sun cycle, and overall solar activity and the earth’s surface temperature, and possible link from changes in IR and visible and IR radiation to changes in earth’s temperatures and climate. p. 33-67 Q27 Maynard, N.C. 1995. "Space Weather Prediction." Reviews of Geophysics (Supplement), 33, (Part 1), 547-557. Washington, D.C.: American Geophysical Union. TIC: 253729. [DIRS 160888] List of engineered systems potentially affected by space weather. p. 547-557 Earth’s Magnetic Field Q28 Odenwald, S. 2003. "Earth - Magnetic Field" Poetry Space Science Education: Ask the Space Scientist http://image.gsfc.nasa.gov/poetry/ask/a skmag.html. [Washington, D.C.]: National Aeronautics and Space Administration. Accessed February 25, 2003. TIC: 253712. [DIRS 160892] The periodicity of pole reversals is on the scale of a few hundred thousand years to once every million years. There has been a decrease in the earth’s magnetic intensity in the last few thousand years, and some evidence that a reversal may occur sometime during the next few to several thousand years. There is no identifiable fossil evidence (such as mutation or extinctions) stemming from magnetic field changes. These statements are made within the citation. Earth Tides Q29 Bredehoeft, J.D. 1997. "Fault Permeability Near Yucca Mountain." Water Resources Research, 33, (11), 2459-2463. Washington, D.C.: American Geophysical Union. TIC: 236570. [DIRS 100007] Earth tides cause fluctuations in water levels at Yucca Mountain that are on the order of a few centimeters p. 2460 give a value of 2.05 cm. The information used for direct input is also identified in Section 4 of the main body of this document, and supporting references are clearly identified in the various subsections of Section 6.2, as needed to provide the technical basis for exclusion of the FEP. ANL-WIS-MD-000019 REV 01 II-8 April 2004 2. DEMONSTRATION OF SUITABILITY USING THE CORROBORATIVE METHOD The data to be evaluated have been extracted from non-project specific source and will be justified for use by the corroborating data approach. The corroborating data approach may be used when subject matter data comparisons can be shown to substantiate or confirm parameter values and may include comparisons of unqualified to unqualified data. The use of the corroborative data approach seems most feasible for judging correctness and reliability by comparing independently developed but related, data sets. This approach is also useful for justifying use of direct inputs and demonstrating suitability for use in the analysis. In this attachment, the indirect input is also referred to as “corroborative-use-only” information to help differentiate it from the direct input being justified for use. In some cases, a single source may provide both direct and indirect input. ANL-WIS-MD-000019 REV 01 II-9 April 2004 3. EVALUATION CRITERIA The following criteria are established for qualifying these data through corroboration. 1. Is there a sufficient quantity of corroborating data available for comparison? Table II-1 is organized by type of information to be evaluated, and each of the sources of data to be evaluated is listed. For each subject area at least two, and preferably three or more, independent sources of information will be considered for corroboration. 2. Can inferences drawn to corroborate these data be clearly identified, justified, and documented? For each source of information to be evaluated, the discussion will include a brief statement regarding the original purpose of the study, the method used to acquire the data, and any limitations germane to the corroboration of the data. Additionally, the basis for assuming adequacy for comparison (e.g., similar type study, update to previous study, compared to previous studies in related fields) will be stated. For quantitative inputs, corroboration will be shown either by graphical representation of the various data sets, or in table or text format, comparing the various values from the various sources. Corroboration will be considered acceptable, if “singular” values (e.g., mean velocity or percent by composition) are shown to be within two standard deviations of the mean value, with the mean and deviations developed by equal weighting of reported mean values from each source. In the case of probability distributions or equations based on probability distributions (e.g., mass flux or cratering rates), corroboration will be considered acceptable if the resulting probability distributions fall within two orders of magnitude for any given point in the distribution (e.g., for the probability of crater diameter of a given size). For qualitative inputs addressing key concepts of a FEP, one or more corroborative information sources will be used to substantiate the direct input. The source(s) should not conflict with the direct input, and should be in general agreement. This standard may also be used when corroborating boundary conditions that define the conditions necessary for the initiation of a FEP (e.g., temperature and pressure conditions associated with the onset of metamorphism). For cases with only one available source of information, the appropriateness for use as direct input will be justified. Therefore, the use of “broad” acceptance criteria is justified, and in lieu of corroboration, a bounding or conservative value (with respect to inclusion of the FEP) may be recommended and considered as qualified under this exercise. Consistent with the intended use, some latitude is taken in applying these criteria and an adequate explanation or justification for variance from the above criteria is provided. For each FEP-specific data set within Section 2, the evaluation criteria to be applied (i.e., quantitative or qualitative) will be identified. ANL-WIS-MD-000019 REV 01 II-10 April 2004 4. EVALUATION OF THE TECHNICAL CORRECTNESS OF THE DATA The technical correctness of the data (and the corroborating information) and hence its suitability to use was evaluated based on the factors listed in AP-SIII.9Q, Section 5.2.1 l), and discussed previously in the introduction to this attachment. Section 4 has been subdivided with direct input for each subject FEP (or grouping of FEPs) being accorded an individual subsection. The discussion of technical correctness for each FEP-specific data set is addressed in four parts. The first part (Section 4.x.1 Literature Search) discusses the scope of the literature review. The literature review involved a keyword search, and the number of returns or “citations” is given. The term “citation” is used in the generic sense and is not specific to either direct inputs or indirect inputs. Preliminary screening of citations based on title and available abstract information was done to help limit the number of citations to be evaluated, and goes to limiting further review to those citations that are related to the properties of interest. The direct inputs to be used were chosen after reviewing the list of selected citations and review of the technical content of the citations. The second part (Section 4.x.2 Evaluation of Factors) addresses the technical correctness of both the data being evaluated, and the corroborating information. The technical correctness of the data and corroborating information was evaluated based on the previous list of factors. . In the summary tables, direct input citations are listed first and are followed by the corroborative citations. A single cited paper might serve as the source for multiple types of direct input and/or reference only information. The designator “Q” within the item identifier indicates the item is to be justified for use. If a direct item is also used to corroborate a different direct input, the “Q” value is listed as corroborating information for that use rather than assigning a “C” number and having a single citation with two designators. In some cases “Q” information is cross- corroborating (i.e., if there is little difference in the listed information) and in some cases a citation may be direct input in one instance, but is used only in a corroborative sense for other information. A “C” designator in the item identifier column indicates the item is used only to corroborate one or more data sets. The first column of the evaluation table addresses the factor “Demonstrates Properties of Interest.” For each source, the evaluation includes a brief statement regarding the original purpose of the study, its applicability, and any limitations germane to use of the information. The factor of “Prior Use by Others” is documented in column 2 of the table. Where possible, this was accomplished by checking against citations in the SciSearch® database or Science Citation Index, which provide the number of other citations which cite back to the subject document. In some instances, the subject document was not found in the SciSearch® database and the number of citations is not known. This is to be expected, as many of these particular articles (such as those related to drill performance) are directed towards technology or engineering application and/or the citation did not initially appear in publications routinely included in the SciSearch® database (such as thesis and textbooks). The factor of reliability of the data source is addressed in the third column (Prior Peer or Other Professional Review) by noting the type of originating document, with peer-reviewed journals being specifically noted. Items listed as “technical journal” denote that the use of peer-review prior to publishing has not been established. Textbooks are noted as such and are typically subject to an editorial and fact ANL-WIS-MD-000019 REV 01 II-11 April 2004 checking. Citations denoted as “articles” rather than “papers” denote information extracted from “reputable” sources, but the reported information has not been subjected to technical review. The reliability of the data source is also considered in Column 4 of the tables (Extent and Reliability of Documentation). This is a subjective evaluation, which was used in part to determine whether a citation should be used as a direct input, with preference as direct input given to those citations with moderate to high documentation levels. If information on equipment and procedures is provided in the citation, it is noted in this column. The fifth column (Importance of the Data) designates the citation as direct input or indirect input, based on its importance to the FEP analysis. By addressing the above listed factors for the corroborative information, the fourth factor (availability of corroborating data) is also addressed. However, the comparison of the direct input to the corroborative information requires more detail and it is specifically addressed under the third subsection (Section 4.x.3 Discussion) for each FEP-specific dataset. The discussions for each FEP may be subdivided by topic to facilitate corroboration of the direct inputs. The fourth part of each section (Section 4.x.4 Data Status and Limitations) provides a recommendations regarding status of the direct input any associated limitations and relates to suitability for use. 4.1 SUITABILITY DEMONSTRATION FOR TIMING OF HUMAN INTRUSION RELATED FEPS The difference in material properties of rock and the engineered barrier system and the effect on drilling parameters may allow recognition of penetration of the engineered barriers. The relationship being evaluated is that: The rate of drill penetration may range from inversely proportional to the square of the compressive strength to inversely proportional to the compressive strength of the rock. This range in relationship is documented in the direct inputs noted as Items Q1 and Q2 in Table II-1. The data are in the form of equations or functional relationships and are qualitative in nature. Therefore, the qualitative criteria for general agreement will be applied. Multiple sources corroborate the data. 4.1.1 Literature Search A literature search was performed using SciSearch® and the GeoRef® databases and was focused on recent papers and updates, and on information directly relevant and applicable to the analysis. The intent of the search was to identify potential citations that addressed factors that would differentiate between drilling in naturally occurring materials and penetration of an engineered barrier. The keyword and subject based-searches utilized various “AND” combinations for the keywords “drilling,” “rate,” “penetration,” and “factors” in various combinations. The SciSearch® database (limited to publication dates for 1980 to 2004) returned a total of three records and the GeoRef® databases (based on all records, including 2004) returned 46 records. Duplicate citations between the two databases were noted, and 12 citations were judged be potentially pertinent for the intended use and further evaluation. Based on existing references used for TSPA-SR, an electronic search of the eLibrary for the Society of Professional Engineers was also performed using the SPE Intelligent Search function with the ANL-WIS-MD-000019 REV 01 II-12 April 2004 input question of “what factors affect rate of penetration and drilling parameters.” The query was set at a 50 percent match and for a return of 200 citations, and no publication date limitation was imposed. From the list of returned citations, four additional citations were marked for further consideration. Additionally, previous discussions of the topic in the final environmental impact statement (FEIS) and total system performance assessment for site recommendation (TSPA-SR) documentation were reviewed and citations in those sources were added to the list. Citations from these sources not selected for evaluation were discarded because they dealt with drilling techniques that are unlikely to be used in groundwater exploration, as required by the regulations. Some other reasons for discarding a citation is that the citation dealt with rock types that are not present at Yucca Mountain above the repository (e.g., shales and limestones), or the paper dealt with specific drilling conditions that were not of interest for shallow conditions. 4.1.2 Evaluation of Factors For each of the sources to be used in the evaluation (whether as direct input, or as indirect input and corroboration of the direct input), the pertinent factors are evaluated in tabular form in Table II-2. ANL-WIS-MD-000019 REV 01 II-13 April 2004 Table II-2. Sources and Factors Evaluation for Direct Inputs to the Timing of Human Intrusion Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others 3. Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Q1 Q2, C2, C3, C4, C6 Bourgoyne, A.T., Jr.; Millheim, K.K.; Chenevert, M.E.; and Young, F.S., Jr. 1986. "Rotary Drilling Bits." Applied Drilling Engineering. [SPE Textbook Series Volume 2]. Pages 190-245. Richardson, Texas: Society of Petroleum Engineers. TIC: 250085. [DIRS 155233] This textbook specifically addresses drilling engineering principles and application of the principles. Chapter 5 specifically addresses the use of rotary drill bits and principles of operations, selection, and factors affecting their operation. Chapter 5 is directly applicable to techniques and practices commonly used in groundwater exploration drilling, which is a regulatory criterion for determining the timing of an intrusion without recognition. Not found in SciSearch® Textbook created in consort by two authors in petroleum engineering academia and two authors from the petroleum industry. This is a standard text for petroleum engineering curriculum. Moderate to High – This text provides a thorough discussion of rotary drill bit performance and provides a variety of equations used in industry to determine the rate of drill bit penetration. Direct Input – The rate of drill penetration may range from inversely proportional to the square of the compressive strength to inversely proportional to the compressive strength of the rock Equation 5-19 directly relates the square of the formation compressive strength to rate of penetration and therefore allows a comparison of behavior based on material properties. Indirect Input - Chapter 5 also provides several discussions regarding drilling principles and practices that are useful for understanding the concepts behind drilling operations. These are discussed in Attachment III of this analysis report and are not further considered herein. ANL-WIS-MD-000019 REV 01 II-14 April 2004 Table II-2. Sources and Factors Evaluation for Direct Inputs to the Timing of Human Intrusion (Continued) Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others 3. Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Q2 Q1 and C1 through C7 Kahraman, S.; Balci, C.; Yazici, S.; and Bilgin, N. 2000. "Prediction of the Penetration Rate of Rotary Blast Hole Drills Using a New Drillability Index." International Journal of Rock Mechanics and Mining Sciences, 37, ([5]), 729-743. [New York, New York]: Pergamon. TIC: 255709. [DIRS 167761] Addresses the interaction of rotary drilling to rock properties. This paper precedes the paper by the same author and used as indirect input. The rock property used for correlation is the ‘drillability index’, which can be defined in terms of tensile strength and unconfined compressive strength. Six citations in SciSearch® Technical journal Moderate to High – A discussion of previous studies, field studies, and laboratory studies is provided. A schematic of the laboratory equipment is provided, and laboratory results are provided in graphical form. The mathematical development of the proposed model using the drillability index is provided. Direct Input – The rate of drill penetration may range from inversely proportional to the square of the compressive strength to inversely proportional to the compressive strength of the rock Eq. 8 of this paper addresses the rate of penetration in terms of a drillability index, but provides a correlation of the index to unconfined compressive strength and to tensile strength in Equations 14 and 15. C1 Not Applicable Beer, F.P. and Johnston, E.R., Jr. 1981. Mechanics of Materials. New York, New York: McGraw-Hill. TIC: 255414. [DIRS 166708] This is a standard engineering text addressing mechanics of materials Not found in SciSearch® Textbook Moderate – This is a standard engineering text. Indirect Input – This text provides information on the relationship of brittle and ductile materials and the respective strength parameters. ANL-WIS-MD-000019 REV 01 II-15 April 2004 Table II-2. Sources and Factors Evaluation for Direct Inputs to the Timing of Human Intrusion (Continued) 3. Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status C2 Not Applicable Bilgesu, H.I.; Tetrick, L.T.; Altmis, U.; Mohaghegh, S.; and Ameri, S. 1997. "A New Approach for the Prediction of Rate of Penetration The paper provides a description of a neural network developed to estimate rates of penetration. It does not specifically link penetration rates to formation properties. It shows the rate of Paper not listed in SciSearch® Proceedings paper – not peer-reviewed Moderate – The paper does not provide any independent validation of the approach used for modeling. Indirect Input – This paper provides corroboration of the factors affecting rate of penetration. (ROP) Values." 1997 SPE Eastern penetration rates based on neural networks of Regional Meeting held in Lexington, Kentucky, October 22-24, 1997. SPE parameters, one of which is formation properties 39231. Pages 175179. Richardson, Texas: Society of Petroleum Engineers. TIC: 255661. [DIRS 167782] ANL-WIS-MD-000019 REV 01 II-16 April 2004 Table II-2. Sources and Factors Evaluation for Direct Inputs to the Timing of Human Intrusion (Continued) 3. Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status C3 Not Applicable Grattan-Bellew, P.E. and Vijay, M.M. 1986. "Influence of Physical Properties of Rock on Rate of Penetration of a Water-Jet Drill." Canadian Mineralogist, 24, 323-328. [Ottawa, Canada: Mineralogical Association of Canada]. Addresses water-jetting drilling techniques, rather than rotary drilling. However, links performance to rock properties. Paper not listed in SciSearch® Technical journal Moderate to Low – This paper provides a limited discussion of laboratory methods and provides optical micrographs to support the conclusions Indirect Input – This paper indicates that commonly measured properties such as compressive strength, tensile strength, and porosity do not correlate with rate of water-jet penetration. This may limit the applicability of material properties being a defining factor for recognition to rotary drilling methods. TIC: 255711. [DIRS 167786] ANL-WIS-MD-000019 REV 01 II-17 April 2004 Table II-2. Sources and Factors Evaluation for Direct Inputs to the Timing of Human Intrusion (Continued) 3. Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status C4 Not Applicable Howarth, D.F.; Adamson, W.R.; and Berndt, J.R. 1986. "Correlation of Model Tunnel Boring and Drilling Machine Performances with Rock Properties." International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 23, (2), 171-175. New This paper provides a link between rock material properties and drilling/tunneling machine performance. Provides correlation of rate of penetrations to three rock properties (compressive strength, saturated density, and P-wave velocity) and for three types of equipment (Tunnel boring machine, diamond drilling and percussive drilling.) 13 citations in SciSearch® Technical journal Moderate-This paper provides a cursory summary of testing equipment and methods, and provides testing results in table and graphical format. Indirect Input – This paper does not address material property strength on rotary drilling, but does confirm that the properties are germane to diamond and percussive drilling. York, New York: Pergamon. TIC: 255620. [DIRS 167645] C5 Not Applicable Kahraman, S. This paper provides a Six citations in Peer-reviewed Moderate to High– This Indirect Input – Figure 5 2002. "Correlation link between a rock SciSearch® journal paper paper provides provides correlation of of TBM and Drilling material property to laboratory test data to three brittleness indices Machine drilling/tunneling support correlation of to rate of penetration. Performances with machine performance rate of penetration to Adequate correlation is Rock Brittleness." Engineering Geology, 65, ([4]), and rotary drilling. It does confirm the relationships of rock various rock properties and cites to supporting papers that provide the shown for factors based on compressive strength and tensile strength. This 269-283. [New properties to drilling laboratory methods can be used to York, New York]: performance. However, corroborate other papers Elsevier. the definitions and using compressive TIC: 255618. [DIRS 167643] assumptions regarding brittleness prevent its use for comparison to strength as a key factor. penetration rates in ductile materials. ANL-WIS-MD-000019 REV 01 II-18 April 2004 Table II-2. Sources and Factors Evaluation for Direct Inputs to the Timing of Human Intrusion (Continued) 3. Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status C6 Not Applicable Kahraman, S.; Bilgin, N.; and Feridunoglu, C. 2003. "Dominant Rock Properties Affecting the Penetration Rate of Percussive Drills." International Journal of Rock Mechanics & Mining Sciences, 40, ([5]), 711-723. [New York, New York]: Pergamon. This paper provides a link between rock material properties and performance of an alternate drilling method. While not directly applicable to rotary bit operation, it does confirm the relationships of rock properties to drilling performance One citation in SciSearch® Technical journal Moderate to High - A discussion of previous studies and experimental studies are provided. Laboratory results are provided in tabular and graphical form along with a statistical analysis of the results. Indirect Input – This paper describes material property correlation to percussive drilling, rather than rotary drilling. However, the rate of penetration is correlated to the uniaxial compressive strength and tensile strength, but poorly correlated to the elasticity modulus for percussive drilling. TIC: 255619. [DIRS 167644] ANL-WIS-MD-000019 REV 01 II-19 April 2004 Table II-2. Sources and Factors Evaluation for Direct Inputs to the Timing of Human Intrusion (Continued) 3. Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status C7 Not Applicable Satchwell, R.M. 1994. An Experimental Study of the Effect of Bedding Plane Anisotrophy on the Rate of Penetration. Ph.D. dissertation. This work addresses the deviation effect of bedding plane anisotropies for three different bit types, include roller cone bits. Dissertations not listed in SciSearch® Doctoral Dissertation High – The documentation satisfies the requirements for a dissertation Indirect Input – provides a summary overview of background information. Provides an equation (cited to Warren) that relates torque to rock strength and rate of penetration. This is used to corroborate the inverse Laramie, Wyoming: University of Wyoming, Department of Chemical and proportionality of rock strength to rate of penetration. Petroleum Engineering. TIC: 255659. [DIRS 167952] C8 Not Applicable Warren, T. M. 1984. "Factors Affecting Torque for a Roller Cone Bit." Journal of Petroleum Technology, [36], ([10]), 1500-1508. Dallas, Texas: This paper provides description relating torque to roller bit performance including the tendency for bit deviation from the vertical. Seven citations in SciSearch® Technical journal Moderate - The paper provides and equation and supporting discussions only. Indirect Input – This is used to corroborate the inverse proportionality of rock strength to rate of penetration. Society of Petroleum Engineers. TIC: 255859 [DIRS 167788] ANL-WIS-MD-000019 REV 01 II-20 April 2004 4.1.3 Discussion The information being justified for use is that: The rate of drill penetration may range from inversely proportional to the square of rock strength, to inversely proportional to the rock strength. This stems from the two equations cited as direct input. Items Q1 and Q2 are being cross-corroborated, and Items C1 through C7 provide corroborating information for both direct inputs. Bourgoyne et al (1986, Equation 5-19 [DIRS 155233]) (Q1) indicates that the relationship of rate of penetration is inversely proportional to the square of compressive strength of the formation. The equation is given as: 2 K . W . W .. (Eq. II-1) 2 R = S .. . dbo -.. . db .. . t . .. N where K = constant of proportionality, S= compressive strength of the rock, W= bit weight, W0threshold bit weight, db = bit diameter, all at time t, and N= rotary speed. All other factors being equal, this indicates that the rate of penetration (R) is affected in a manner inversely proportional to the square of the compressive strength. Bourgoyne et al (1986, [DIRS 155233]) (Q1) cites to another author that indicates that the rate of penetration is directly proportional to K, which is a constant of proportionality that includes the effect of rock strength, although it does not indicate whether an inverse square relationship is represented in the value for K. Kahraman et al. (2000, Equation 8 [DIRS 167761]) (Q2) cross-corroborates to Bourgoyne et al (1986, [DIRS 155233]) (Q1). The equation used by Kahraman stems from the same source as that used by Bourgoyne et al. However, Kahraman expresses the equation in terms of a drillability index, which is then shown to have an inverse proportionality to compressive strength and tensile strength, rather than an inverse square relationship. The corroborating equation is given by Kahraman as: NW PR = 20.3 aD (Eq. II-2) where PR = penetration rate, N= rotation speed, W= bit weight, a = the drillability index and D = the bit diameter. The drillability index, a is then expressed in terms of compressive strength, sc. Eq. 12 of Kahraman et al. (2000 DIRS [167761]) (Q2) sc = 09 .3 a+ 13.14 (Eq. II-3) ANL-WIS-MD-000019 REV 01 II-21 April 2004 A simple substitution of terms generates an equivalent equation: NW PR 20.3 = 13.14 s c .. - .. D 09.3 (Eq. II-4) Similarly, Eq. 14 of the same paper provides a correlation to tensile strength, in the form of sT = 22.0 +a 11.2 (Eq. II-5) A simple substitution of terms generates an equivalent equation: NW PR 20 . 3 = 11.2 s T .. . - .. . D 22.0 (Eq. II-6) Thus from Bourgoyne et al. (1986, Equation 5-19 [DIRS 155233]) (Q1), the relationship is shown to be inversely proportional to square of the compressive strength, and from Kahraman et al. (2000, Equation 8 [DIRS 167761]) (Q2), the relationship is shown to be only inversely proportional to either the compressive strength or the tensile strength. How is it then that these two equations are considered cross-corroborative? Based on Equation II-4, a doubling of compressive strength from 20 to 40 MPa, and then from 40 MPa to 80 MPa would, in the first instance result in a 4 times decrease in the rate of penetration (i.e., the inverse square relationship as suggested by Bourgoyne et. al). However, with progressive doubling, from 40 MPa to 80 MPa, Equation II-4 above gives about a 2.5 times decrease in penetration rates. A third doubling of strength from 80 MPa to 160 MPa would result in a decrease of about 2.5 times, and a fourth doubling from 160 MPa to 320 MPa indicates a decrease of about 1.8 times. Similar relationships can be seen for the tensile strength. Based on Equation II-6, and assuming tensile strengths of 4, 8, 16, and 32 MPa, then the decrease in penetration rate, respectively, are factors of 3.1, 2.4, and 2.2. This suggests that the correlation proposed by Kahraman et al. (2000, Equation 8 [DIRS 167761]) (and Equation II-2 above) is not a linear relationship, and at lower values may approach or exceed an inverse square relationship. Kahraman notes that the proposed inverse relationship is based on a coefficient value for data points with compressive strengths greater the 40 MPa, because of poor correlation with experimental results at lower compressive strengths. If this equation were then applied to lower compressive strength materials, it would be expected that the estimated penetration rates would be understated. Bourgoyne does not discuss any upper limitations on the applicability of the equation based on rock strength. Thus, the two relationships are not contradictory and are cross-corroborative at least for the lower range of unconfined compressive strength and for tensile strength. ANL-WIS-MD-000019 REV 01 II-22 April 2004 The two equations (Eq. II-3 and II-5, above) from Kahraman are corroborated from four sources (Items C1, C5, C7 and C8). First, if the relationships are correct, then the ratio for compressive strength and tensile strength should be between a factor of ten and twenty. This is based on the general assumption that for brittle materials, that tensile strength should be about 10 to 20 percent of the compressive strength. In general, brittle materials are significantly stronger in compression than in tension (Beer and Johnston (1981 p. 37 [DIRS 166708]) (C1). For example, the tensile strength of concrete is about 10 to 20 percent of its compressive strength, and rock properties at the site (See Attachment III) also indicate a ratio of 10 to 20 for compressive strength to tensile strength. Assuming a hypothetical drillability index of one, and substituting into Equations 3 and 5 above, yields a ratio of sc/sT = 17.22/2.33 = 7.4. Assuming a drillability index of 100 yields a ratio of sc/sT = 323.13/24.11= 13.4. Therefore, the relationship between the equations is at least reasonable and internally consistent with the rock property used as the basis for the conclusions in Kahraman (2000, Table 2 [DIRS 167761]), (Q2). A second line of corroboration is the relationships based on brittleness also proposed by Kahraman (2002 DIRS [167643]),(C5). Because the data set is the same as that used for Kahraman (2000 DIRs [167761]) (Q2), but the principles used to develop the relationships in the data are different, the later paper can be used to corroborate the first. In Kahraman (2002 DIRS [167643]) (C5), the developed equations relate the rate of penetration to parameter values that incorporate both compressive strength and tensile strength of a material. Kahraman (2002 DIRS [167643]) (C5) indicates the rate of penetration is correlatable to the brittleness B1, which is defined as the ratio of the compressive strength to the tensile strength; and to B2, which is the ratio of compressive strength minus tensile strength to the compressive strength plus the tensile strength. The equations developed use the ratio of parameters involving both the unconfined compressive strength and the tensile strength. Given that they are shown to correlate to penetration rates lends support to the appropriateness of the original equations (Equations 3 and 5 above), wherein the compressive strength and the tensile strength are related to the drillability coefficient and hence to the penetration rate. Thirdly, Satchwell (1994, Equation 6-4-1, DIRS [167952]) (C7), citing to Warren (1984 [DIRS 167788]) (C8) indicates that the bit torque is proportional to the penetration rate and to the rock strength. 1 .. . p . .. . . p ( 2 ER D 2 N - WR ) (Eq. II-7) ..a .. = 4 T Isolation of the variable for penetration rate (R) indicates that the penetration rate (R) is inversely proportional to rock strength (E), rather than inversely proportional to the square of the rock strength (E). This further corroborates the results from Kahraman (2000, Equation 8 [DIRS 167761]) (Q2). Further general corroboration for the direct input taken both Bourgoyne et al. (1986 [DIRS 155233]) and for Kahraman (2000 [DIRS 167761]) (Q2) stem from the remaining corroborative sources (C2, C3, C4, C6). Bilgesu et al. (1997 [DIRS 167782]) (C2) indicates that key factors in determining rate of penetration include weight on bit, rotary speed, pump rates, bit type and formation harness. Bilegsu et al. expresses the formation characteristics as formation ANL-WIS-MD-000019 REV 01 II-23 April 2004 drillability and formation abrasiveness. Grattan-Bellew and Vijay (1986 [DIRS 167786]) (C3), in evaluating water jetting, indicate that “though not applicable to water-jet drilling, commonly measured physical properties of rock, for example, compressive strength, tensile strength, specific gravity, and porosity, do not correlate water-jet penetration.” They indicate, however, that the mechanics of water jet drilling are different from rotary drilling (i.e., fracture propagation rather than cratering and chip formation), so the lack of correlation is to be expected. The dependency of rotary drill penetration on unconfined compressive strength also is corroborated from other multiple sources, though these are not directly applicable to rotary drilling. Howarth et al. (1986 Figure 2 [DIRS 167645]) (C4) indicate that for percussion drilling, a doubling of the saturated compressive strength from 50 MPa to 100 MPa, the penetration rate fits a non-linear curve and decreases from 100 mm/min to 50 mm/min. Howarth et al., however, demonstrated that there was no significant correlation to dry compressive strength for percussion drilling. Kahraman (2002 DIRS [167643]) (C5) provides a list 10 papers by other authors to indicate that uniaxial compressive strength is the most widely used parameter for predicting the performance of tunneling machines and drilling rigs, though the exact relationship is not given or further discussed. Kahraman (2003 [DIRS 167644]) (C6), in contrast to Howarth et al., (1986, [DIRS 167645]) (C4) indicates that for percussive drills the relation of penetration rate to uniaxial compressive strength is a linear relationship. 4.1.4 Data Status and Limitations The stated relationship that the rate of drill penetration may range from inversely proportional to the square of the compressive strength to inversely proportional to the compressive strength of the rock stems from the two direct input sources listed in Section 4.1.2. The equations from those two direct inputs have been adequately corroborated from multiple sources, and all sources evaluated are in general agreement. Thus, the qualitative criteria for general agreement have been met. Corroboration of the direct input provides the required level of confidence that the data are suitable for their intended use, which is for FEP Screening. The status of the stated relationship and the related direct inputs evaluated above should be considered as qualified for use within this technical product. However, limitations apply. The direct inputs are entirely adequate, based on compressive strength and tensile strength properties, to support a conceptual argument that significant changes in drill performance would occur and be recognized if a bit penetrates the drift wall or crown (naturally occurring material) and then encounters a metallic or alloy material used for the engineered barrier system. The exact relationship of unconfined compressive strength on the penetration rate, however, is not entirely certain. The relationship does not appear to an inverse square relationship as suggested by Bourgoyne et al (1986 DIRS [155233]) (Q1) for greater material strengths, but does appears to be something less that that relationship. However, the corroborative information clearly suggests that an inverse square relationship likely represents the upper bound in the range of relationship. A more supportable position is that the relationship is inversely proportional. ANL-WIS-MD-000019 REV 01 II-24 April 2004 Accordingly, a limitation on use of the data is imposed: the upper bound of an inverse square relationship shown from Bourgoyne et al. (1986 [DIRs 155233]) (Q1) may be mentioned, but the FEP screening decision should be determined based on the better substantiated, but less dramatic change in rate of penetration suggested by Kahraman (2000 DIRS [167761]) (Q2). As will be discussed in Attachment III of this analysis report, the rock and engineered barrier material strength unconfined compressive strengths are significantly greater than 40 MPa. Although both direct input relationships have been corroborated, the more linear relationship suggested by Kahraman for greater material strengths better addresses site conditions, and is more conservative. That is, a greater difference in material properties is required to induce a similar and noticeable change in drilling conditions and, thus, creates a more stringent threshold to use in FEPs screening. 4.2 SUITABILITY DEMONSTRATION FOR DIRECT INPUTS FOR FEP 1.4.11.00.0A EXPLOSIONS AND CRASHES (HUMAN ACTIVITY) This section addresses direct inputs related to the energy released and depth of effects resulting from explosions and crashes. The four following statements, and the supporting direct inputs, are being justified for use. The energy release required to create a crater with a diameter sufficient to fracture to 60 m or 200 m (i.e., the depths of interest) are on the order of 1012 to 1017 Joules. This information is taken from Item Q4 in Table II-1. Kinetic energy for jet aircraft is approximately 2 tons TNT equivalent or less. This is taken from Item Q8 in Table II-1. The energy yield of conventional weapons is on the order of 2 tons or less. This is taken from Item Q5 in Table II-1. The maximum penetration depth of earth penetrating weapons is approximately 30 m. This information is drawn from Items Q3, Q6, Q7, and Q9 in Table II-1. The energy release from underground nuclear detonations results in fracturing to distances on the order of 100 meters or less. This information is taken from Item Q4 in Table II-1. The direct input being justified is in the form of equations or functional relationships, or they are empirical data. The objective is to justify input representing the maximum possible effects (i.e., upper bound of possible conditions) against a theoretical threshold of significance (i.e., minimum depth or energy release needed to be of significance). Therefore, the quantitative criteria will be applied, but conservative values will be recommended 4.2.1 Literature Search A literature search was performed using SciSearch® and the GeoRef® databases and was focused on recent papers and updates directly relevant and applicable to the analysis. The intent of the search was to identify potential citations that addressed factors that would identify the magnitude of various explosion and crash scenarios, and their effect in the subsurface. Various ANL-WIS-MD-000019 REV 01 II-25 April 2004 key-word searches based on the terms “earth penetrating weapons”, “subsurface” effects”, “explosions” and “crashes” were performed. In total, the SciSearch® database (limited to publication dates for 1980 to 2004) returned a no pertinent records and the GeoRef® databases (based on all records including 2004) returned five pertinent records. Because of the sparse amount of information, the reference lists for these five citations were then reviewed to identify any other pertinent papers, and an Internet search was performed. The resulting citation list is provided in Table II-3. 4.2.2 Evaluation of Factors For each of the sources to be used in the evaluation (whether as direct input or reference only and corroboration of the direct input), pertinent factors are evaluated in tabular form in Table II-3 ANL-WIS-MD-000019 REV 01 II-26 April 2004 Table II-3. Sources and Evaluation for Direct Input to Explosions and Crashes Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others 3. Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Q3 Q6, Q7, Q9 and Q5, C11, C13, C14 Backman, M.E. and Goldsmith, W. 1978. "The Mechanics of Penetration of Projectiles into Targets." International Journal of Engineering Science, 16, (1), 1-99. New York, New York: Pergamon. TIC: 255605. [DIRS 167628] Applicable – The entire paper is concerned with terminal ballistics and the penetration mechanics for various categories of targets and types of penetrators. Earth materials are discussed as semi-infinite targets and various factors are discussed. Equations for determining depth of penetration are provided. 160 citations in SciSearch® Peer-reviewed Technical journal High – This is a summary work addressing a variety of projectile characteristics, target characteristics and equations from a wide variety of sources. Extensively cited and extensive bibliography provided. Direct Input – The maximum penetration depth of earth penetrating weapons is approximately 30m The relationships and equations giving depth of penetration are taken from: p. 32, For steel projectile with a length- to-diameter ratio of 8, striking normally at 150 m/s. Penetration depth into sand of 350 diameters, and for high- strength concrete (5,000 psi strength), a penetration depth of 25 diameters. The Poncelet equation (Equation 6.2 on p. 38) and factors from Table 2 for hard soils (95 percent sand and, 5 percent silt a8 = 15.7, a10 = 24.7). ANL-WIS-MD-000019 REV 01 II-27 April 2004 Table II-3. Sources and Factors Evaluation for Direct Input to Explosions and Crashes (Continued) 1. 3. Item Corroborating Items Source Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Q4 C10, C11, C12 Dence, M.R.; Grieve, Figure 12 of The effects This paper was Moderate – This paper Direct Input – R.A.F.; and Robertson, P.B. 1977. "Terrestrial Impact Structures: Principal Characteristics and Energy Considerations." Impact and Explosion Cratering, Planetary and Terrestrial Implications, Proceedings of the Symposium on Planetary Cratering Mechanics, Flagstaff, Arizona, September 1317, 1976. Roddy, D.J.; Pepin, R.O.; and Merrill, R.B., eds. Pages 247275. New York, New York: Pergamon Press. TIC: 247237. this paper relates energy release to crater diameter. Diameter can then be equated to excavation and fracturing depth, which are of direct interest. addressed in this paper have been used in other repository design considerations regarding meteorite impact. The energy release equations are often cited in other works in the subject area. Science Citation Index indicate 17 citations extracted from an edited compendium of related works. provides a summary of characteristics of craters and respective dimension and compares cratering effects to those of nuclear testing. No information on procedures or quality control is provided. The energy release required to create a crater with a diameter sufficient to fracture to 60 m or 200 m (i.e., the depths of interest) are on the order of 1012 to 1017 Joule. Figure 12 is used to relate energy release to crater diameter and hence to fracturing and cratering depth. The energy release from underground nuclear detonations results in fracturing to distances on the order of 100 meters or less. p. 262 indicates that [DIRS 135253] the 64-kt Pile Driver test produced stresses at about 100 meters (328 feet) that were slightly less than those needed to propagate fractures in granodiorite. Q5 Q8, C13. C16. Ferguson, C.D. 2002. "Mini-Nuclear Weapons and the U.S. Nuclear Posture Review." Monterey, California: Monterey Institute of International Studies, This paper mentions and briefly discusses existing conventional and potential Article not listed in SciSearch® This is essentially and editorial article from a public policy institute rather than a scientifically- Low – article provides a brief discussion of various weapons capability, but citations are primarily to policy and position papers rather than to technical papers. Direct Input – The energy yield of conventional weapons is on the order of 2 tons. This is based on direct input from this citation ANL-WIS-MD-000019 REV 01 II-28 April 2004 Table II-3. Sources and Factors Evaluation for Direct Input to Explosions and Crashes (Continued) Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others 3. Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Center for Nonproliferation Studies. Accessed December 4, 2002. http://www.cns.miis.edu /pubs/week/020408.htm TIC: 253717. [DIRS 160988] nuclear earth penetrating weapons. oriented or technical article Weapons capabilities are provided only as attributed quotes. stating that an explosive capability of 2 tons is given for the GBU-28 explosive ordnance. Indirect Input – The depths stated in the paper may be biased to understating the potential depth of penetration. However, they do provide a minimum or lower bound of possible penetration depths. Used to corroborate depth of penetrations calculated based on Backman and Goldsmith and results of experimental test data from Forrestal et al; from Young, and from Patterson. Q6 Q3, Q7, Q8, Q9 and Q5 C11, C14, C15 Forrestal, M.J.; Longcope, D.B.; and Norwood, F.R. 1981. "A Model to Estimate Forces on Conical Penetrators Into Dry Porous Rock." Journal of Applied Mechanics, 48, (1), 25-29. New York, New York: American Society of Mechanical Engineers. This journal paper develops a model to predict the forces exerted on conical- nosed penetrators for normal impact into dry rock targets. Results of an experimental 14 citations in SciSearch® Peer-reviewed journal paper Moderate – Experimental test results for a conical penetrator into tuff are provided and a citation to a correspondence is given. Information on the projectile characteristics and the target material are provided and are adequate to judge comparability to Yucca Mountain geo-materials. Direct Input – The maximum penetration depth of earth penetrating weapons is approximately 30 m Direct input from this paper (p. 28) indicates that experimental test results at the Sandia, Tonopah Test Range, Nevada indicate a penetrator; 1.52 m ANL-WIS-MD-000019 REV 01 II-29 April 2004 Table II-3. Sources and Factors Evaluation for Direct Input to Explosions and Crashes (Continued) Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others 3. Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status TIC: 255607. [DIRS 167630] test into a tuff unit are cited as corroboration to the model results. The experimental results are directly applicable long, with outer diameter of 0.165 m and mass of 182 kg, with an initial velocity of 411 m/s penetrated to a depth of 2.6 m. in an unsaturated, welded tuff. Q7 Q3, Q6, Q8, Q9 and Q5, C11, C14 Patterson, W.J. 1974. "Results and Analysis of Three Instrumented Projectile Penetration Tests at the Watching Hills Blast Range, Suffield, Alberta, Canada." EOS, Transactions, 56, (12), 1197. Washington, D.C.: American Geophysical Union. TIC: 255677. [DIRS 167805] This abstract provides results of experimental data for penetrators into geomaterials and the information is directly applicable. Abstract not listed in SciSearch® This is information provide only in abstract form and was presumably not subject to peer- review Low – the nature of the publication and its presentation only in abstract form provides only the barest of documentation Direct Input – The maximum penetration depth of earth penetrating weapons is approximately 30 m Provides empirical information on rock penetrations tests. Penetrators with a diameter of 15.24 cm and mass of 181.4 kg were fired with impact velocities of 93 m/sec, 122.8 m/s and 150.9 m/sec and achieved penetration depths of 9.08 meters, 14.72 meters, and 20.7 m respectively. The target material was an old glacial lake bed. Q8 C9 Stix, G. and Yam, P. 2001. "Facing a New Menace." Scientific American, 285, (5), 1415. [New York, New This paper addresses airline security and screening issues. One citation in SciSearch® This article extracted from a respected scientific journal, but is Moderate – The calculation results in the sidebar are straightforward calculations and the Direct Input – Kinetic energy for jet aircraft is approximately 2 tons TNT equivalent or less ANL-WIS-MD-000019 REV 01 II-30 April 2004 Table II-3. Sources and Factors Evaluation for Direct Input to Explosions and Crashes (Continued) Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others 3. Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status York]: Scientific American. TIC: 254304. [DIRS 160994] However, a sidebar column provides the results of calculations for various energies related to airliner impacts. non-technical in content and likely not peer reviewed bases for the calculations are given. They are adequate for use in FEPs screening This information provides energy release associated with a large jetliner (Boeing 767) crash. Q9 Q3, Q7, Q9 and C11, C14 Young, C.W., 1976. Status Report on High Velocity Soil Penetration Program. SAND76-0291. Albuquerque, New Mexico: Sandia National Laboratories. ACC: MOL.20040407.0069 [DIRS 167806] This is an investigation report prepared for Sandia Laboratories regarding earth penetration. It is applicable because it provides experimental data for the depth of penetration in soils. Paper not listed in SciSearch® National laboratory report Moderate – Experimental results are discussed and provided. In particular, description of penetrators and targets are provided. Direct Input – The maximum penetration depth of earth penetrating weapons is approximately 30 m. Provides empirical information on soil penetration tests, Table II--1 indicates that a penetrator with a weight of 320 lbs, and 6.0 inch diameter impacting with a speed of 2316 feet per second penetrated 220.5 (67 m) feet into a hard playa soil. C9 Not Applicable Abbas, H.; Paul, D.K.; Godbole, P.N.; and Nayak, G.C. 1996. "Aircraft Crash Upon Outer Containment of Nuclear Power Plant." Nuclear Engineering and Design, 160, ([12]), 13-50. [New York, This paper addresses aircraft impact on above- ground structures – particularly containment buildings for Three citations in SciSearch® Peer-reviewed journal paper Moderate - This paper develops the equations needed to analyze reaction forces and stresses within a cylindrical containment building and provides a comparison to other similar types of studies. Indirect Input – Provides a linear mass density for three types of aircraft. This can be used to calculate approximate kinetic energy of various aircraft. Input data by ANL-WIS-MD-000019 REV 01 II-31 April 2004 Table II-3. Sources and Factors Evaluation for Direct Input to Explosions and Crashes (Continued) 1. 3. Item Corroborating Items Source Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status New York]: Elsevier. TIC: 255604. [DIRS 167627] nuclear power plants. Paper considers the linear mass density and crushing strength of a Boeing 707320, FB-111 jet fighter , and the F4 Phantom jet fighter. However, the reference list appears limited, and citations for the aircraft characteristics are not provided. aircraft type include: Boeing 707-320: Velocity of 102.8 m/s, linear mass density of 9,000 kg/m, total length of 40 m. FB-111 : Velocity of 108.2 m/sec, linear mass density of 9000 kg/m, total length of 22 m F4 Phantom: Velocity of 215.8 m/sec, linear mass density of 3500 kg/m, total length of 16 m. Provides corroboration for calculations cited from Stix and Yam. C10 Not Applicable Glasstone, S. and Dolan, P.J., eds. 1977. "Descriptions of Nuclear Explosions." Chapter II of The Effects of Nuclear Weapons. 3rd Edition. Pages 26-79. Washington, D.C.: U.S. Department of Defense and This document provides and overview of the effects of nuclear weapons, including effects of underground detonations. This is a government- sponsored document and was developed through interagency cooperation. Moderate – This document is a thorough overview of the topic, and technical discussion is provided. It summarizes the results of underground nuclear testing. Indirect Input – Section 2.104 provides a description of fracturing related to the RAINIER test. U.S. Department of Energy. ACC: MOL.20030925.0035. [DIRS 160992] C11 Not Applicable Gronlund, L. and Wright, D. 2002. "Earth Penetrating Weapons" This paper mentions and briefly Article not listed in SciSearch® This is essentially an editorial article Low – article provides a brief discussion of various weapons Indirect Input – The penetration depths stated in the paper may ANL-WIS-MD-000019 REV 01 II-32 April 2004 Table II-3. Sources and Factors Evaluation for Direct Input to Explosions and Crashes (Continued) 1. 3. Item Corroborating Items Source Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Global Security Cambridge, Massachusetts: Union of Concerned Scientists. Accessed December 10, 2002. TIC: 253714. [DIRS 160989] http://www.ucsusa.org/g lobal_security/nuclear_ weapons/page.cfm?pag eID=777 discusses existing conventional and potential nuclear earth penetrating weapons. from a public policy institute rather than a scientifically- oriented or technical article capabilities, but citations are primarily to policy and position papers rather than to technical papers. Weapons capabilities are provided only as attributed quotes. be biased to understating the potential depth of penetration. However, they do provide a minimum or lower bound of possible penetration depths. Containment depths for subsurface explosions are stated. Used to corroborate depth of penetrations calculated based on Backman and Goldsmith and results of experimental test data from Forrestal et al; from Young, and from Patterson, (i.e., reported penetrations of 6 m of concrete and 30 m of earth). Also used to indicate the depths required to contain an explosion (60 meters for a one-kiloton explosion, and 300 meters for a 100kiloton explosion). C12 Not Applicable Hughes, D.W. 1998. "The Mass Distribution of Crater-Producing Bodies." Meteorites: Flux with Time and Impact Effects. This paper is directed to addressing factors that define basic relationships of Paper not listed in SciSearch® This paper was extracted from an edited and refereed compendium of the London Moderate – Paper provides a good summary of preceding work by others and performs an evaluation of these various sets and Indirect Input – Figure 3 provides a direct comparison to works by Dence et al. and to works by others, and therefore provides ANL-WIS-MD-000019 REV 01 II-33 April 2004 Table II-3. Sources and Factors Evaluation for Direct Input to Explosions and Crashes (Continued) 1. 3. Item Corroborating Items Source Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Geological Society meteor flux to Geologic ranges of equation. The a strong corroborative Special Publication No. cratering rates. Society (31 figure of interest provides source indicating that 140. Grady, M.M.; However, the referees, citations to the original use of the relationships Hutchison, R.; McCall, author takes an including two source documentation of proposed by Dence G.J.H.; and Rothery, energy-based whom are works by others. et al. are reasonable D.A.; eds. equation routinely cited for use as direct input. Pages 31-42. Bath, approach and in meteorite England: Geological provides a impact work). Society of London. figure that TIC: 254143. [DIRS 162562] summarizes the results of multiple studies that link energy releases to crater diameters C13 Not Applicable Lennox, D.; Rees, A. (eds.) 1990. Jane's Air- Launched Weapons. Alexandria, Virginia: Jane's Information Group. TIC: 255862 [DIRS 167804] Provides the “best source” of information from unclassified materials for weapons capabilities and descriptions Not listed in SciSearch® The Jane’s series of books are widely recognized as an acceptable source of unclassified information on weapons systems for most countries Moderate to High – This highly respected series of books contain information collected from a variety of unclassified sources including government documents and vendor information. Indirect Input – the mass of the largest weapons of various types are taken from the appendix. A conservative assumption is made that the total mass is attributed to high explosives, and an equivalent energy release is calculated. For air-to-surface missiles, the largest warhead is 1,000 kg of HE (USSR AS-4, AS-5, and AS-6) For bombs, the greatest weight is 9000 kg (Iraq NASR-9000). Largest diameter ANL-WIS-MD-000019 REV 01 II-34 April 2004 Table II-3. Sources and Factors Evaluation for Direct Input to Explosions and Crashes (Continued) 1. 3. Item Corroborating Items Source Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status weapon is 1 meter diameter. Typically, warhead and weights are 1,000 kg or less, and diameters are generally 0.5 m or less. C14 Not Applicable Nelson, R.W. 2001. "Low-Yield Earth- Penetrating Nuclear Weapons." FAS Public Interest Report, 54, (1), 1-5. Washington, D.C.: Federation of American Scientists. TIC: 253719. [DIRS 160986] This paper mentions and briefly discusses existing conventional and potential nuclear earth penetrating weapons. Article not listed in SciSearch® This is essentially an editorial article from a public policy institute rather than a scientifically- oriented or technical article Low – article provides a brief discussion of various weapons capabilities, but citations are primarily to policy and position papers rather than to technical papers. Weapons capabilities are provided only as attributed quotes. Indirect Input – The depths stated in the paper may be biased to understating the potential depth of penetration. However, they do provide a minimum or lower bound of possible penetration depths. Containment depths for subsurface explosions are stated. Used to corroborate depth of penetrations calculated based on Backman and Goldsmith and results of experimental test data from Forrestal et. al; from Young, and from Patterson C15 Not Applicable Siddiqui, N.A. and This paper No citations in Peer-reviewed Moderate - The reliability Indirect Input – Abbas, H. 2002. "Mechanics of Missile reexamines the work by SciSearch® journal is comparable to that of Forrestal et al. This paper reexamines and modifies the Penetration into Geo- Materials." Structural Engineering and Forrestal and refines the model. approach taken by Forrestal et. al. Mechanics, 13, (6), 639-652. [Taejon, Korea: Techno-Press]. ANL-WIS-MD-000019 REV 01 II-35 April 2004 Table II-3. Sources and Factors Evaluation for Direct Input to Explosions and Crashes (Continued) 1. 3. Item Corroborating Items Source Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status TIC: 255608. [DIRS 167631] C16 Not Applicable Wu, C. 2000. "Powerful Explosive Blasts onto Scene." Science News Online, 157, (4), 54. . TIC: 255698 [DIRS 167812] This is a general news article dealing with development of a new explosive compound. This is pertinent to determining the equivalent Article not listed in SciSearch® This article was taken from an Internet-based weekly science magazine. It has not been peer-reviewed, but the contents of the article have been confirmed by finding a Low to Moderate – Information is traceable to a somewhat obscure scientific journal, therefore reliability is established. However, the basis for statements regarding relative strength of the high explosive to TNT is not traceable Indirect Input – Provides justification for assumption that the explosive yield of HE is no more than twice that of a comparable weight of TNT. energy similar citation released from a conventional in a peer- reviewed HE warhead. journal (Angewandte Chemi International). ANL-WIS-MD-000019 REV 01 II-36 April 2004 4.2.3 Discussion The following discussion has been subdivided by topic, with direct inputs grouped accordingly. The topics of discussion include energy release needed to fracture to depth, kinetic energy release from aircraft, conventional weapons yields, maximum depth of penetration, and fracturing effects from underground nuclear explosions. 4.2.3.1 Energy Release to Depth of Effect Relationships The relationship being justified is that The energy release required to create a crater with a diameter sufficient to fracture to 60 m or 200 m (i.e., the depths of interest) are on the order of 1012 to 1017 Joule. This relationship is direct input from Item Q4, and is corroborated by the studies summarized in Item C12. Dence et al. (1977 Figure 12 [DIRS 135253]) (Q4) provides a series of curves relating energy release to the surface to crater diameter that is used as direct input. The crater diameters of interest for impact to the repository are 80 m for fracturing to the depth of a key geologic unit (a depth of 60 m, on the order of 300 m for fracturing to repository depth and on the order of 1,000 m for exhumation to repository depth (a depth of 200 m) as explained in Attachment IV of this analysis report. For these depths, the curve from Dence et al. (1977 [DIRS 135253]) (Q4) indicates that energy releases at the surface on the order of 1012 to 1017 joules, or greater could potentially cause damage to the repository. The relationships presented in Dence et al. (1977 [DIRS 135253]) (Q4) are corroborated by a similar figure presented in Hughes (1998 Figure 3 [DIRS 162562]) (C12). Hughes shows the Dence et al. curve in relation to similar curves developed by five other investigators. For the range of diameters of interest, the plot from Dence et al. is shown to be the least conservative (i.e., more energy required for a given diameter), with other investigators showing that a crater with a given diameter could be produced with less energy. The lowest most curve shown by Hughes requires approximately an order of magnitude less energy than that required by Dence et al. For a 1 km diameter crater, Dence et al. requires approximately 1023 ergs, while the lowermost curve requires 1022 ergs (equating to 1017 and 10 16 joules respectively). At a diameter of 100 m, the required energies are 1020 ergs and 1019 ergs (1013 and 1012 joules respectively). Thus use of the curve from Dence et al. (1977 Figure 12 [DIRS 135253]) (Q4) with a stated range of 1012 to 1017 joules is corroborated by Hughes (1998, Figure 3 [DIRS 162562]) (C12). However, because the values from Dence et al. are the least conservative, a limitation on the use of the data is discussed in Section 4.2.4.1. 4.2.3.2 Energy Released by Aircraft Impact The bounding condition being justified is that: Kinetic energy for jet aircraft is approximately 2 tons TNT equivalent or less. ANL-WIS-MD-000019 REV 01 II-37 April 2004 This value was taken as direct input from Item Q8 and is corroborated, based on three different aircrafts, using information from Item C9. Stix and Yam (2001 [DIRS 160994]) (Q8) provide, in a sidebar column, the results of calculations for energy released from a jet airliner crash (1 to 2 tons TNT equivalent), excluding the release from on-board fuel. In Stix and Yam (2001 [DIRS 160994]) (Q8), the stated mass of a Boeing 767, larger than the aircraft listed below and fully loaded, is listed as 412,000 pounds (186,880 kg), and the stated kinetic energy for a velocity of 530 mph (237 m/s) is given as the equivalent of 1 ton TNT. With regard to aircraft crashes and the associated energy release, an equivalent calculation for three types of aircraft used in analyzing the aircraft crash hazard for nuclear power plants is given for corroboration. In the corroborating source, Abbas et al (1996 Figures 9, 10, 11; and p 25 [DIRS 167627]) (C9) provide the information on mass distribution and velocity for various size aircraft. These can be used to determine the kinetic energy available upon impact. Table II-4. Corroborative Information for Determining Kinetic Energy of Various Aircraft Aircraft Type Velocity (m/s) Total Length (m) Linear Mass Density (kg/m) (approximate length and associated density) Mass (kg) Kinetic Energy (at stated velocity) Ke = 1/2mv2 (kg-m2)/s2 or Joules TNT Equivalent (tons) (1 ton TNT = 4.2 x 109 Joules) Boeing 102.8 40 0-15 m – 2000 kg/m 30,000 707-320 15-25 m – 10,000 kg/m 25-40 m – 2000 kg/m100,000 30,000 8.5 x 108 0.2 160,000 FB-111 102.8 22 0-11 m – 2000 kg/m 11-15 m-9000 kg/m 15-22 m-3000 kg/m 22,000 36,000 21,000 79,000 4.2 x 108 0.1 F4 Phantom 215.8 16 0-5 m 10,000 kg/m 5-7 m 25,000 kg/m 7-10m – 40,000 kg/m 5,000 5,000 12,0007.0 x 10 8 0.17 10-16 m – 20,000 kg/m 8,000 30,000 If the stated velocity for the Boeing 707 and for the FB-111 is scaled upward to 236 m/s, then a factor of 2.3 is applied to the velocity. Given that the kinetic energy is a function of the square of the velocity, an increase of 2.3 times would increase the kinetic energy by 5.3 times, and the corresponding release in TNT equivalent would increase by that same factor. This would equate to a release of approximately 1 ton from the Boeing 707-320, and less for the other aircraft shown. Thus, the energy release given by Stix and Yam in corroborated using equivalent information from Abbas et al (1996 [DIRS 167627]) (C9), and the direct input is shown to be at the upper range of likely releases from aircraft impacts. ANL-WIS-MD-000019 REV 01 II-38 April 2004 4.2.3.3 Energy Released by Targeted Weapons The direct inputs discussed in this section are used to determine whether the energy releases by targeted weapons are capable of affecting the repository at depth, based on the curve from Dence et al. (1977 Figure 12 [DIRS 135253]) (Q4) described in Section 4.2.3.2 of this attachment. The condition being justified is that: The energy yield of conventional weapons is on the order of 2 tons. This is taken as direct input from Item Q5, and is corroborated by information presented in Q8, C13, and C16. The direct input is based on Ferguson (2002 [DIRS 160988]), (Q5), who states an explosive capability of 2 tons for the GBU-28. Based on corroborative sources, this direct input appears to be a reasonable representation of the upper end of yields from conventional weapons. Corroboration is based on information taken from Jane’s Air-Launched Weapons (Lennox and Rees (1990 [DIRS 167804]) (C13). This is the “standard” unclassified resource for weapons systems information. The appendices provide total mass and dimensions for missiles and bombs from all major countries, as well as the mass of warheads and/or mass of the munition in terms of high explosives, without specifying the type of high explosive. To convert to equivalence in TNT, a factor of 2 is assumed. This is based primarily on Wu (2000 [DIRS 167812]) (C16). Wu reports on the synthesization of a new explosive compound (octanitrocubane) that is stated to be “twice as powerful as trinitrotoluene (TNT) and it’s thought to be 20 to 25 percent more effective than HMX (octagen), which is the state-of-the-art military explosive right now”. The statement is attributed to a source at the Nation Institute of Standards and Technology. Accordingly, a factor of 2 is assumed to convert from mass of high explosive to equivalence of TNT. Further corroboration is provided by Stix and Yam (2001 [DIRS 160994]) (Q8), who indicate that the energy release for a U.S. cruise missile (with a conventional warhead) is 0.5 ton TNT equivalent. With regard to the reported TNT equivalent of 0.5 tons for a Tomahawk cruise missile with conventional warhead, Lennox and Rees reports that the U.S AGM-131 SRAM conventional warhead contains 250 kg of high explosive. Using the factor of 2-multiplier, this suggests that the yield cited by Stix and Yam above is correct. Additional corroborative information from Lennox and Rees (1990 [DIRS 167804]) (C13) indicates that the largest conventional warheads for air-to surface missiles are listed as 1,000 kg HE, and are associated with the former USSR AS-4 and AS-6 air to surface missiles. This would be equivalent to 2,000 kg TNT (or about 2 tons) TNT. With regard to bombs (such as the GBU-28), Lennox and Rees indicates that the total weight of Iraq’s NASR-9000 is 9,000 kg. If all this mass were attributed to HE, then the TNT equivalent would be upwards of 9 tons of TNT. However, for most of the bombs listed by Lennox and Rees, the total weight is typically a few hundred to a thousand kg, suggesting that TNT equivalents of about 1 ton are more “typical.” Accordingly, a suggested value of 2 ton TNT equivalent for conventional ordnance is corroborated and considered suitable for use in FEP Screening considerations. ANL-WIS-MD-000019 REV 01 II-39 April 2004 4.2.3.4 Maximum Depth of Penetration Given that the repository is located no less than 200 m below the ground surface, the maximum depth of penetration of a projectile in dry rock is of particular interest. The condition being justified is that: The maximum penetration depth of earth penetrating weapons is approximately 30 m. This stems from direct inputs either based on, or taken, from Items Q3, Q6, Q7, Q9 (which are all cross-corroborating) and are further corroborated either directly by, or using information from, Q5, C11, C13, C14, and C15. Direct input is taken from Backman and Goldstein (1978 pp. 32 through 38 [DIRS 167628]) (Q3) in the form of a table stating penetration depths in terms of projectile diameters, and in the form of the Poncelet equations and associated resistance constants for hard soil. Direct Input is also taken from Forrestal et al. (1981 [DIRS 167630]) (Q6), Patterson (1974 [DIRS 167805]) (Q7), and from Young (1976 [DIRS 167806]) (Q9), which present results of experimental data in a variety of geo-materials. Backman and Goldstein (1978, p. 32 [DIRS 167628]), (Q3) indicates that for a round-ended steel projectile with a length to diameter ratio of 8, striking normally at 150 m/s, sand will be penetrated to a depth of 350 diameters, and high strength concrete (5000 psi compressive strength) will be penetrated to a depth of only 25 diameters. Given that samples of the volcanic tuff, with only a few exceptions, exhibit compressive strengths of well in excess of 50 MPa (or in excess of 7500 psi), as shown in Attachment III of this analysis report, a value associated with 5000 psi concrete can be chosen as a conservative surrogate. However, to calculate a maximum penetration depth, a projectile diameter is needed. A maximum diameter of 1 meter is assumed based on information from the corroborating source, Lennox and Rees (1990, [DIRS 167804]) (diameter for the NASR 9000, C13). Accordingly, the maximum penetration depth will be on the order of 25 meters in the volcanic tuffs present at the site. Backman and Goldstein (1978, Eq. 6-2 and p. 38 [DIRS 167628]) (Q3) also cite to the Poncelet equation, which indicates that the depth of penetration (P) is dependent on two resistance constants a10 and a8. The equation is given as: 2 v a 10 + . . . 1 ln . m P = o (Eq. II-8) . . 2a a 10 8 For this equation, P is the penetration depth in cm, m is the mass in kg, and vo is the impact velocity in m/sec. The resistance coefficients for hard soil are given as a8 = 15.7 and a10=24.7. Assuming a mass of 9,000 kg (again based on the maximum mass reported in Lennox and Rees (1990 [DIRS 167804]) (total mass for the NASR 9000, C13), and assuming a mid-range velocity of 411 m/sec, yields a penetration depth of 22.8 m (2,275 cm). These results based on the relationships and equations in Backman and Goldstein can be cross- corroborated along with the experimental data from the following direct input sources. Experimental data from Young (1976, Table II [DIRS 167806]) (Q9) indicate a maximum ANL-WIS-MD-000019 REV 01 II-40 April 2004 penetration depth of 220 feet (67 meters) into hard playa lake soils composed of sand, silt and clay. The compressive strengths of these materials ranged from approximately 300 psf to 45,000 psf (13 to 312 psi). These tests were made with a 6-inch (0.15 m) diameter projectile. A significant increase in penetration depths in sandy soils versus rock is expected, as Backman and Goldstein (1978 p.32 [DIRS 167628]) (Q3) indicates total penetration depth for sand is 350 times the diameter, compared to 25 diameters for concrete-equivalent compressive strengths. Thus for a 0.15 m diameter projectile, a penetration depth of 53 m could be expected in sand. These results (i.e., 67 m from experimental data and 53 m by equation) can be cross-corroborated to Patterson (1974 [DIRS 167805]) (Q7) by taking into account the difference in target materials. Patterson reports a penetration depths ranging from 9.08 meters of 20.7 m into a glacial lakebed, a harder geo-material than that targeted by Young (1976 [DIRS 167806]). The Patterson tests were conducted using a penetrator of mass of 181.4 kg and diameter of 0.152 m. Initial velocities ranged from 93 m/s to 150.9 m/s. Backman and Goldstein provide an intermediate value of 36 diameters for 2500 psi strength material. Applying the factors of 36 and 350 diameters (to bound the potential depths of penetration), provides anticipated depth of penetration from 5.4m to 52.5 m. Using Eq. 8 above (the Poncelet equation from Backman and Goldstein), the estimated depths of penetration would be 0.3 m to 38.5 m. In either case, the experimental results from Patterson are bracketed by the calculated depths based on Backman and Goldstein, and taking into account the difference in geo-materials, substantiates the results from Young (1976 [DIRS 167806]). One further cross-corroboration can be made to the results of Forrestal et al. (1981 p. 28 [DIRS 167630]) (Q6). Forrestal et al. report that penetration depth in an unsaturated, welded tuff achieved a penetration depth of only 2.6 m. This is significant in that the materials at Yucca Mountain are a series of unwelded and welded tuffs. This penetration depth was achieved using a penetrator of mass of 182 kg and diameter of 0.165 m and initial velocity of 411 m/s. The measured depth of penetration was 2.6 m. Using these values, and substituting into the equations presented by Blackman and Goldstein, provides estimated depths of penetration of 4.1 m using a penetration factor of 25 diameters. However, the unconfined compressive strength of welded tuff materials is on the order of 100 MPa or greater (14,500 psi) (see Attachment III of this analysis report for rock property information). This is about three times the compressive strength used to determine the factor of 25 diameters. Thus, an overestimate of penetration depth should be anticipated. Application of Equation 8 above suggests an anticipated depth of penetration of about 0.5 m. Thus, the experimental data (2.6 m) is bounded by the range (0.5 m to 4.1m) in the calculated data, and they are considered corroborative. The results of Forrestal et al. are independently corroborated with the indirect input taken from the additional work of Siddiqui and Abbas (2002 [DIRS 167631]) (Item C15 above), who refined the theoretical estimated penetration depth to be 2.9 m. Given that the calculated depths and experimental depths have been shown to be corroborative, and given values for maximum penetration depths of 25 m (calculated for an assumed maximum diameter), 60.7 m (observed for hard playa soils), 20. 7 m (observed for glacial lake bed), and 2.6 m (observed for an unsaturated welded tuff), then the averaged value for depth of penetration is 29 m. Thus, the statement that: “The maximum penetration depth of earth penetrating weapons is approximately 30 m,” is defensible and reasonable. This is particularly so, given that the penetration into a welded volcanic tuff was a factor of 10 less than that value of being used as ANL-WIS-MD-000019 REV 01 II-41 April 2004 bounding condition, and is probably more representative of site conditions than the other direct inputs. The direct inputs, and the calculated average, are corroborated from two additional sources used as indirect inputs (Items C11 and C14). Gronlund and Wright (2002 [DIRS 160989]) (C11) indicate that the U.S. arsenal includes two air dropped weapons that are capable of penetrating six meters of concrete or 30 meters of earth. Additionally, Nelson (2001 [DIRS 160986]) (C14) suggests a maximum penetration depth to be on the order of 100 feet (33 meters) based on long rod penetration, and projects that the maximum penetration depth can be no more than 10 times the length of the penetrator. These indirect inputs corroborate the direct inputs discussed above. 4.2.3.5 Fracturing Effects of Underground Nuclear Explosions The FEP description for explosions and crashes specifically mentions the potential for nuclear war and underground testing. Although, as discussed for the FEP, there is basis for a regulatory exclusion, direct inputs also indicate that these events would be of low consequence. The condition being justified is: The energy release from underground nuclear detonations results in fracturing to distances on the order of 100 meters or less. This is based on direct input taken from Item Q4, and is corroborated by Items C10 and C11. Dence et al. (1977 p. 262 [DIRS 135253]) (Q4) provide the direct input by reference to the 64-kt Pile Driver test producing stresses at about 100 meters (328 feet) that were slightly less than those needed to propagate fractures in granodiorite. This is corroborated by two indirect input sources. Glasstone and Dolan (1977 Section 2.104 [DIRS 160992]) (C10) describe the results of the RAINIER underground nuclear test. The authors indicate that the deep (240 meters, 790 feet) underground detonation of the 1.7-kt event fractured the surrounding materials out to a radius of only 54 meters (180 feet)—which is less than one drift spacing. In describing the penetration depth needed to contain an underground detonation, Gronlund and Wright (2002 [DIRS 160989]) (C11) indicate that a depth of 60 meters would contain a one-kiloton explosion, and 300 meters would contain a 100-kiloton explosion. Thus, for detonation less than 100-kiloton, the stated condition is corroborated, as is the direct input taken from Dence et al. 4.2.4 Data Status and Limitations For quantitative data, the criteria regarding standard deviations and establishment of conservative bounding values have been satisfied. The above literature review and corroboration of the direct input provides a suitable level of confidence that the data are suitable for their intended use, which is for FEP Screening. The status of the direct input evaluated above should be considered as qualified for use within this technical product. However, some limitations apply. 4.2.4.1 Energy Release to Depth of Effect Relationships Use of the curve from Dence et al. (1977 Figure 12 [DIRS 135253]) (Q4) with a stated range of 1012 to 1017 joules is corroborated by Hughes (1998, Figure 3 [DIRS 162562]) (C12). However, the lower threshold for FEP screening should be based on 1012 joules to ensure that the lower ANL-WIS-MD-000019 REV 01 II-42 April 2004 range of energy levels documented in corroborating sources cited by Hughes has been adequately addressed. 4.2.4.2 Energy Released by Aircraft Impact The energy release for a large jet aircraft given by Stix and Yam (2001 [DIRS 160994]) (Q8) has been corroborated and shown to be at the upper range of likely releases from aircraft impacts. However, it should be noted that the calculated energy release pertains only to kinetic energy, and does not consider other factors such as explosion of on-board fuel, detonation of on-board ordnance, or other factors. 4.2.4.3 Energy Released by Targeted Weapons Ferguson (2002 [DIRS 160988]) (Q5) states an explosive capability of 2 tons for the GBU-28. This value has been corroborated and is believed to be representative of possible energy releases from conventional weapons systems. However, the maximum potential release, though speculative, should be mentioned to ensure that conservative bounding values have been taken into account and used to address the range in uncertainty. 4.2.4.4 Maximum Depth of Penetration Based on these various cross-corroborating and independently corroborating sources, a maximum depth of penetration of 30 m into volcanic tuffs should be used. The penetration factor of 25 diameters reported by Backman and Goldstein (1978 p. 32 [DIRS 167628]) (Q3); the reported value of 67 m from Young (1976, Table II [DIRS 167806]) (Q9); the maximum value of 20.7 m from Patterson (1974 [DIRS 167805]); and the value of 2.6 m from Forrestal et al. (1981, p. 28 [DIRS 167630]) (Q6) have been cross-corroborated and are judged appropriate for use in FEP screening analysis. However, the value of 67 m represents conditions that are unlikely to be encountered at Yucca Mountain. Tests on material similar to that at Yucca Mountain yielded the value of only 2.6 m. Consequently, a conservative, but reasonable, bounding value for the maximum penetration depth at the site would be approximately 30 m, based on the cited source information and corroborating information used as indirect input. 4.2.4.5 Fracturing Effects of Underground Nuclear Explosions For detonation less than 100-kiloton, the stated condition is corroborated. Use of the 100-m fracturing extent should quote Dence et al. (1977 p. 262 [DIRS 135253]) (Q3) directly to avoid uncertainty regarding a bound on the yield of the detonation. 4.3 SUITABILITY DEMONSTRATION FOR DIRECT INPUTS FOR FEP 1.2.05.00.0A METAMORPHISM The conditions being justified are stated in the form of boundary conditions required for the onset of regional metamorphism. ANL-WIS-MD-000019 REV 01 II-43 April 2004 The minimum conditions needed for onset of metamorphism are: T> 150-200ºC P = 0.5-1 kbar Depth = 4-5 km The range in geothermal gradients is 10 to 25º and the pressure gradient is approximately 0.6 kbar/km The following statements are based on information taken from Item Q10, and are shown to be conservative bounding conditions by corroboration with Items C17, C18, and C19. For the FEPs analysis, all that is needed is to show that existing burial rates and geothermal gradients are insufficient to result in significant temperature and pressure increases. Therefore, the qualitative criteria for general agreement will be applied. The criteria specifically indicate that this standard may be used when corroborating boundary conditions that define the conditions necessary for the initiation of a feature, event, or process (e.g., temperature and pressure conditions associated with metamorphism). 4.3.1 Literature Search A review of available “at-hand” geology textbooks was conducted to verify conditions necessary for metamorphism to occur. The intent of the search was to verify that the conditions being used as direct input could be corroborated with other sources. In reviewing sources to be used for evaluating diagenetic effects, a third corroborating source was identified and has been evaluated. 4.3.2 Evaluation of Factors For each of the sources to be used in the justification (whether as direct input or indirect input and used for corroboration of the direct input), pertinent factors are evaluated in tabular form in Table II-5. ANL-WIS-MD-000019 REV 01 II-44 April 2004 Table II-5. Sources and Factors Evaluation for Direct Inputs to Metamorphism 1. 3. 4. Items Corroborating Items Source Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review Extent and Reliability of Documentation 5. Proposed Input Status Q10 C17, C18, C19 Ehlers, E.G. and Blatt, H. 1982. Petrology, Igneous, Sedimentary, and Metamorphic. New York, New York: W.H. Freeman and This is a standard petrology textbook and contains applicable discussions and text. Not Applicable Textbook All that is needed here is a statement of temperature and pressure ranges that represent the onset of Direct Input - The minimum conditions needed for onset of metamorphism are: T> 150-200ºC P = 0.5-1 kbar Depth = 4-5 km Company. metamorphism. p. 566 TIC: 255657. [DIRS 167802] The range in geothermal gradients is 10 to 25ºC and the pressure gradient is approximately 0.6 kbar/km pp. 684-685 and p. 169, Figure 3. C17 Not Applicable Hyndman, D.W. 1972. Petrology of Igneous and Metamorphic Rocks. International Series in the Earth and Planetary Sciences. New York, New York: McGraw-Hill. TIC: 248141. This is a standard geology textbook and contains applicable discussions and text. Not Applicable Textbook All that is needed here is a statement of temperature and pressure ranges that represent the onset of metamorphism. Indirect Input – This text provides corroborative information for metamorphic conditions From p, 270 “ Temperatures of about 300 to 400 degrees C to 700 to 800 degrees C. Geothermal gradients average about 15 to 25 degrees C/km for margins, compared to about 10 degrees C/km for stable shield area.” [DIRS 150295] From p. 272, Pressures are uncertain but for most areas are estimated to range from about 2,000 or 3,000 bars (or atmospheres). The normal load pressure at depth, resulting from the weight of overlying rocks, is about 285 bars/km. ANL-WIS-MD-000019 REV 01 II-45 April 2004 Table II-5. Sources and Factors Evaluation for Direct Inputs to Metamorphism (Continued) 1. 3. 4. Items Corroborating Items Source Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review Extent and Reliability of Documentation 5. Proposed Input Status C18 Not Applicable Press, F. and Siever, R. 1978. Earth. 2nd Edition. Chapters 11 and 16. San Francisco, California: W. H. Freeman and Company. TIC: 255856. [DIRS 167965] This is a standard geology textbook and contains applicable discussions and text. Not Applicable Textbook All that is needed here is a statement of temperature and pressure ranges that represent the onset of metamorphism. Indirect Input – This text provides corroborative information for metamorphic conditions From p. 303, “As a sediment is buried, it becomes subjected to increasingly high temperatures – on the average of 1ºC for each 30 meters (100 feet) of depth – and high pressures – on the average about 1 atmosphere for each 4.4 meters. The boundary between diagenesis and metamorphism is somewhat arbitrary, usually drawn at a temperature of about 300 degrees C. C19 Not Applicable Retallack, G. J. 1991. "Untangling the Effects of Burial Alteration and Ancient This paper focuses on defining and describing differences and Book not found in SciSearch ® This paper was extracted from a book series. Moderate – The paper is focused on distinguishing between burial Indirect Input – The paper focuses on information for related to diagenesis effects. However, it also defines the onset of Soil Formation." Annual Review of Earth and Planetary Sciences. effects associated with burial alteration and soil formation. alteration affects and characteristic of ancient soils. metamorphism. p. 200 “in excess of 200 º C and depths greater than 7 km.” Weatherhill, G. Vol. 19, 183-206. Palo Alto, California: Annual Reviews Inc. TIC: 255912. [DIRS 167870] The paper provides a survey of applicable studies by others, and a lengthy citation list is provided. ANL-WIS-MD-000019 REV 01 II-46 April 2004 4.3.3 Discussion The direct input for this FEP is taken from Ehlers and Blatt (1982, [DIRS 167802]), (Q10), largely because the values they present suggest the least temperature, pressure and depth of burial needed for the onset of regional metamorphism (i.e., conservative bounding conditions for onset). Using it as the basis of the FEPs screening is, therefore, conservative. It is corroborated by two other texts: Hyndman (1972 p. 270 and 272 [DIRS 150295]), (C17) and Press and Siever (1978, pp. 303) [DIRS 167965]), (C18), and from a third book source, Retallack (1991, p. 200 [DIRS 167870]), (C19). Table II-6. Comparison of Various Stated Conditions for Metamorphism Source Temperature Gradient Pressure Gradient Onset Temperature Onset Pressure Onset Depth Ehlers and Blatt, Approximately Approximately 1 150 – 200 ºC Pressures Depth within 1982 TIC: 255657 1000 degrees C per 100 km or 10 Mbar per 1500 km or equivalent of 0.6 (p. 566) on the order of 0.5-1 kbar the crust of about 4-5 km [DIRS 167802], Q10) degrees C/km (p. 169, Figure 63) kbar/km (p 169, Figure 6-3) (p. 566). (p.566) Hyndman,1972 TIC: 248141 [DIRS 150295, C17] About 10 degrees C/km for stable shield area, and average about 15 to 25 degrees C/km for a “geosynclinal” environment About 285 bars/km, or 0.28 kbar/km (p. 272) 300 to 400 ºC (p. 270) About 2,000 or 3,000 bars (or atm); equivalent to 2 to 3 kbars (p. 272) Not Given (p. 270) Press and Siever, 1978 TIC: 255856 [DIRS 167965], C18 Average of 1 degree C for each 30 meters (100 feet) of depth or about 33 degrees/km About 1 atmosphere for each 4.4 meters, or about 0.3 kbars/km (p. 303). About 300 ºC (p. 303) Not Given Not Given (p. 303) Retallack (1991), Not Given Not Given In excess of Not given Greater than 7 C19 200 ºC km (p. 200) TIC: 255912 (p. 200) [DIRS 167870] Ehlers and Blatt (1982, p. 566 [DIRS 167802]) (Q10) indicate 0.5 to 1 kbar is necessary for the onset of metamorphism, which is clearly conservative compared to Hyndman (1972 p. 272 [DIRS 150295]) (C17), which indicates that 2 to 3 kbars of pressure are required. The onset temperature, 150 – 200 ºC given by Ehlers and Blatt (1982, p. 566 [DIRS 167802]) (Q10), is also clearly conservative and as much as one-half of that cited by the corroborating sources. Given the respective pressure gradients, Ehlers and Blatt (1982 p. 566 [DIRS 167802]) (Q10) would suggest metamorphic onset at depths as little as 1 to 2 km, but also clearly indicate a burial depth of 4 to 5 km is needed. In any case, these conditions are clearly conservative compared to the temperature and pressures, and to the depth of 10 km, based on Hyndman’s information. They are also clearly conservative compared to the 9 km depth based on the ANL-WIS-MD-000019 REV 01 II-47 April 2004 average thermal gradient, and they are conservative with respect to the onset temperatures presented by Press and Siever (1978 p. 303 [DIRS 167965]) (C18). They are also more restrictive than the conditions indicated by Retallack (1991 p. 200 [DIRS 167870]) (C19) of greater than 200ºC and burial greater than 7 km. 4.3.4 Data Status and Limitations For qualitative data, the criterion of general agreement has been satisfied. The above literature review and corroboration of the direct input provides an acceptable level of confidence that the data are suitable for their intended use, which is for FEP Screening. The status of the direct input for metamorphism from Ehlers and Blatt (1982 p. 566 [DIRS 167802]) (Q10) evaluated above should be considered as qualified for use within this technical product. Because they represent the lowest temperature and pressure required for the onset of metamorphism, no further limitation on their use is required. 4.4 SUITABILITY DEMONSTRATION FOR DIRECT INPUTS FOR FEP 1.2.08.00.0A DIAGENESIS Diagenesis is an ongoing process of chemical and physical changes to sediments undergoing compaction, cementation, and burial. The conditions being evaluated and the associated direct input are as follows: The time required for complete diagenesis to occur is less than 10,000 years: This is taken from Items Q11 and Q12. SiO2 cementation is not dependent of climatic conditions, but cementation does exhibit distinctive trends that correspond with the ages of the surficial deposits: This is taken from Item Q15. Accumulation rates are attributable to several climatic scenarios, but climate change was insufficient to significantly decrease the rate of accumulations: This is taken from Item Q15. CaCO3 may translocate to greater depths given greater precipitation, and cementation is a reversible effect: This is taken from Item Q15. Compaction does not become an important factor until the onset of deep burial: This is taken from Item Q11. The net effect of shallow diagenesis is to stabilize the surface environment and decrease the net infiltration rate: This is taken from Item Q14. Cementation by CaCO3 is not a significant process in rhyolitic tuff due to the lack of carbonate source material: This is taken from Items Q11, Q13, and Q15. Cements other than carbonate may develop: This is taken from Items Q11, Q13, and Q15. ANL-WIS-MD-000019 REV 01 II-48 April 2004 Accumulation rates for Yucca Mountain favor SiO2 over CaCO3, which is accessory cement: This is taken from Items Q13 and Q15. The data being evaluated include Items Q11 through Q15 in Table II-1. The data is in the form of conceptual statements and is generally qualitative in nature. Therefore, the qualitative criteria for general agreement will be applied. 4.4.1 Literature Search A literature search was performed using SciSearch® and the GeoRef® databases and was focused on recent papers and updates directly relevant and applicable to the analysis. The intent of the search was to identify potential citations that addressed factors that significantly affected rates of diagenesis in arid environments and that quantified the effects of diagenesis in the near subsurface (less than 1 km). The keyword and subject based searches utilized various “AND” combinations for the keywords “diagenesis”, “silcrete” “duricrust”, “duripans”, “effects”, “factors”, and “infiltration” in various combinations. The SciSearch® database (limited to publication dates for 1900 to 2004), for the search term “diagenesis” alone returned 2,940 returns. Addition of the search term “shallow” restricted the search to 380 returns, and further restriction with “effects” generated one return; this was found to not be of particular interest. Use of the combined terms “diagenesis” and "effects” yielded 423 returns. These 423 returns were evaluated based on titles and available abstracts, and only two citations appeared applicable. Use of the individual search terms “silcrete,” “duricrust,” and “duripans” returned 26, 12, and 2 records, respectively. Only one of these citations was judged applicable. Using the GeoRef® database, the search on “diagenesis” returned 37,855 records. Restricting the search by adding the term “effects” limited the search to 1900 returns. Further restriction by adding the term “infiltration” yielded only five records. These were reviewed by title and abstract, and none were found applicable. Other searches using various search terms such as “calcrete”, “arid” “cementation” “duirpan” and “polygenesis” yield a few more useable citations. Searches on the term “silcrete” yield 352 returns, and addition of the word “effects” restricted the search and yielded only nine returns. A similar search for “duricrust” and “effects” yield 11 returns. These 11 records were reviewed by title and available abstract, and none were found to be applicable. The bibliographies of citations were then reviewed to identify other sources that might be of interest. The combined result of the searches and the preliminary review based on titles and abstracts is reflected in the lists of citations provided in Table II-7, below. Citations that were not selected for evaluation were discarded because they dealt with deep diagenetic processes, were focused on description of the characteristics and properties of formations not of particular interest to Yucca Mountain (such as marine deposits or large scale sedimentary and costal basin), or did not appear to characterize the net change in properties since initial disposition or describe factors that affected the rate and extent of the diagenetic process. Additionally, most of the papers available focused on the interrelationship between the formation properties and the potential impact on petroleum or natural gas exploration or production. 4.4.2 Evaluation of Factors For each of the sources to be used in the evaluation (whether as direct input or reference only and corroboration of the direct input), pertinent factors are evaluated in tabular form in Table II-7. ANL-WIS-MD-000019 REV 01 II-49 April 2004 Table II-7. Sources and Factors Evaluation for Direct Inputs to Diagenesis Item Corroborating Item Source 1. Demonstrates Properties of Interest 2. Prior Use by Others 3. Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Q11 Q12, Q15, C20, C21, C23, C25, C28, C29, C30, C31 Krystinik, L.F. 1990. "Early Diagenesis in Continental Eolian Deposits." Chapter 8 of Modern and Ancient Eolian Deposits: Petroleum Exploration and Production. Fryberger, S.G.; Krystinik, L.F.; and Schenk, C.J., eds. Denver, Colorado: Society of Economic Paleontologists and Mineralogists, Rocky Mountain Section. TIC: 247781. [DIRS 135295] This information is taken from a chapter describing early diagenesis in continental eolian deposits and is directly applicable to diagenesis in arid environments. Book not found in SciSearch® Special book publication Moderate – The text provides adequate citations to support the summary discussion of diagenetic processes, and provides summary tables and figures as needed. Direct Input –The time required for complete diagenesis to occur is less than 10,000 years (p. 8-1) that lithification in desert environments can occur within 5,000 years, and Compaction does not become an important factor until the onset of deep burial: (pp. 8-2 and 8-3) that after initial settling compaction is not a significant diagenetic process until significant burial depth is achieved. Cementation by CaCO3 is not a significant process in rhyolitic tuff due to the lack of carbonate source material: Cements other than carbonate may develop It also indicates (p. 8-4) that iron, aluminum, and silica may be the primary cements, rather than carbonate. ANL-WIS-MD-000019 REV 01 II-50 April 2004 Table II-7. Sources and Factors Evaluation for Direct Inputs to Diagenesis (Continued) Item Corroborating Item Source 1. Demonstrates Properties of Interest 2. Prior Use by Others 3. Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Q12 Q11, C20, C25, C23, C31 Lattman, L.H. and Simonberg, E.M. 1971. "Case- Hardening of Carbonate Alluvium and Colluvium, Spring Mountains, Nevada." Journal of Sedimentary Petrology, 41, (1), 274-281. [Tulsa, Oklahoma: Society of Economic Paleontologists and Mineralogists]. TIC: 223189. [DIRS 129306] This paper describes field observations on carbonate alluvium and colluvium near Las Vegas, Nevada. Because of the field study location and the nature of the observations, the results are applicable, but likely overstate the case for igneous source materials. Paper not found in SciSearch® Peer-reviewed journal Moderate – This paper addresses field observations rather than laboratory analysis. Field procedures are not discussed, and the number of supporting citations is limited. Direct Input – The time required for complete diagenesis to occur is less than 10,000 years The paper indicates (p. 277) that case hardening can occur within a few tens of years. Q13 Q15 Lattman, L.H. 1973. "Calcium Carbonate Cementation of Alluvial Fans in Southern Nevada." Geological Society of America Bulletin, 84, (9), 3013-3028. Boulder, Colorado: Geological Society of America. TIC: 235904. [DIRS 129305] This paper addresses cementation effects in alluvium and colluvium in southeastern Nevada. The author discusses these processes for basic and igneous material in the absence of a carbonate source, which is a directly applicable situation. Paper not found in SciSearch® Technical journal Low to Moderate – This paper addresses field observations rather than laboratory analysis. Field procedures are not discussed, but a bibliography of cited sources is provided. Direct Input – Cementation by CaCO3 is not a significant process in rhyolitic tuff due to the lack of carbonate source material (p. 3015) states that calcification is not a significant process for rhyolitic tuffs unless a source for carbonates is present. Q14 Q15, C20, C27 Reeves, C.C. 1976. Caliche: Origin, Classification, Morphology and This book was the only text found devoted to the formation of caliche Book not found in SciSearch® Book High- This book is a survey and comparison of pertinent studies on calcrete, silcrete and other duripans. Direct Input – The net effect of shallow diagenesis is to stabilize the surface ANL-WIS-MD-000019 REV 01 II-51 April 2004 Table II-7. Sources and Factors Evaluation for Direct Inputs to Diagenesis (Continued) Item Corroborating Item Source 1. Demonstrates Properties of Interest 2. Prior Use by Others 3. Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Uses. Lubbock, Texas: Estacado Books. TIC: 245928. [DIRS 104303] and other duripans. environment and decrease the net infiltration rate s. The book states (p. 110) that the net effect is to decrease infiltration. Q15 Q11, Q14, Q13, C22, C24, C26, C28, C30 Taylor, E.M. 1986. Impact of Time and Climate on Quaternary Soils in the Yucca Mountain Area of the Nevada Test Site. Master's thesis. [Boulder, Colorado]: University of Colorado. TIC: 218287. [DIRS 102864] This is a Master’s thesis focusing on correlation of soils characteristics to paleoclimate effects. Citation not found in SciSearch® Thesis – not subject to peer-review, but subject to academic defense. Moderate to High Because this is a Master’s thesis, the degree of documentation is high, although the quality of the data has not been evaluated within the thesis itself. Direct Input – SiO2 cementation is not dependent on climatic conditions, but cementation does exhibit distinctive trends that correspond with the ages of the surficial deposits (p. 86) Accumulation rates are attributable to several climatic scenarios, but climate change was insufficient to significantly decrease the rate of accumulations: (p. 89) CaCO3 may translocate to greater depths given greater precipitation, and cementation is a reversible effect (p.82) Cementation by CaCO3 is not a significant process in rhyolitic tuff due to the ANL-WIS-MD-000019 REV 01 II-52 April 2004 Table II-7. Sources and Factors Evaluation for Direct Inputs to Diagenesis (Continued) 1. 3. Item Corroborating Item Source Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status lack of carbonate source material Cements other than carbonate may develop. Accumulation rates for Yucca Mountain favor SiO2 over Ca CO3, which is an accessory cement (p. 33) The relationships of CaCO3 and opaline Si02 for Yucca Mountain soils to climate change are provided (Chapter 5). Additionally, (Figure 9 and pp. 31-33) the relative importance of Si02 over CaCO3, is discussed. C20 Not Applicable Arakel, A.V. 1996. This paper Paper not Peer-reviewed Low to Moderate – This Indirect Input – This "Quaternary Vadose describes the listed in journal, but paper appears to be a paper provides Calcretes Revisited." AGSO Journal of Australian Geology and Geophysics, 16, formation and distribution of calcretes in arid vadose zone of SciSearch® with restricted focus to Australian geology. survey of other studies done in the region and is focused on overarching trends in the information, corroboration for the conceptualization of initial plugging of porosity and (3), 223-229. western Australia rather than on detailed permeability (p. 223), [Canberra], Australia: and is, therefore, descriptions of factors and and for the “rapid” [Australian potentially effects. maturation of Government Public applicable. cemented soil profiles Service] TIC: 255481 [DIRS 167623] However, the focus is on establishing various soil profiles within a relatively short time (p. 226). with respect to paleoenvironmental reconstruction and ANL-WIS-MD-000019 REV 01 II-53 April 2004 Table II-7. Sources and Factors Evaluation for Direct Inputs to Diagenesis (Continued) 1. 3. Item Corroborating Item Source Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status mineral exploration activities. C21 Not Applicable Baldwin, B. and Butler, C. O. 1985. "Compaction Curve." American Association of Petroleum Geologists Bulletin, 69, (4), 622-626. Tulsa, Oklahoma: American Association This paper provides compaction curves for sandstones and shales, and shows changes in solidity with burial depth. 161 citations in SciSearch® Technical journal Moderate to High – This paper presents a brief review of earlier papers describing compaction curves and provide adequate citations. The paper compares the proposed curves to results of the other studies and Indirect Input – This paper reproduces the Sclater-Christie sandstone curve (Figure 3), which shows the solidity (i.e., the complement of porosity) is nearly constant above about of Petroleum Geologists. TIC: 255917. discusses the implications of the results and the limitations of other types of 100 m, and it approaches but never reaches 100 percents. [DIRS 167871] curves. C22 Not Applicable Chadwick, O.A.; Nettleton, W.D.; and Staidl, G.J. 1995. "Soil Polygenesis as a Function of This paper describes a soil profile transect in the northern Great Basin, and shows Seven citations on SciSearch® Peer-reviewed journal. Moderate to High – This paper provides an extensive set of tables that summarize various analysis done on soils collected Indirect Input – This paper provides corroboration that climate change drives soil characteristics Quaternary Climate Change, Northern Great Basin, USA." Geoderma, 68, ([12]), 1-26. [New York, New York]: Elsevier. TIC: 255603. the relationship between climate changes and pedogenic processes. along the transect. related to the presence and/or depth distribution of opaline silica, and calcium carbonate. It also indicates that desert loess accumulation is [DIRS 167626] episodic, accumulating more rapidly during interpluvial periods, and the resulting soil profiles have greater surface area, which tends to increase water retention and mineral weathering and decrease the ANL-WIS-MD-000019 REV 01 II-54 April 2004 Table II-7. Sources and Factors Evaluation for Direct Inputs to Diagenesis (Continued) 1. 3. Item Corroborating Item Source Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status depth of leaching for a given precipitation regime. C23 Not Applicable Eghbal, M.K. and Southard, R.J. 1993. "Stratigraphy and Genesis of Durorthids and Haplargids on Dissected Alluvial Fans, Western Mojave Desert, California." Geoderma, 59, ([14]), 151-174. Amsterdam, The This paper addresses geomorphology and soils in a desert environment of southwestern California that is similar in many ways to the Yucca Mountain Region. The paper reports results of a trench Five citations in SciSearch® Peer-reviewed journal Moderate to High – Detailed soil profile descriptions are provided along with a summary of laboratory methods used for the analyses. The basis for conclusions is clearly stated Indirect Input – This paper provides a corroborative value for rate of CaCO3 accumulation needed to form a duripan compared to estimated accumulation rates (pp. 170-171) and attributes the excess accumulation to bioturbation. Netherlands: Elsevier. TIC: 255601. study through an alluvial fan [DIRS 167624] sequence and associated soils and draws conclusions regarding the distribution of associated duripans. C24 Not Applicable Eghbal, M.K. and Southard, R.J. 1993. "Micromorphological This paper addresses geomorphology Seven citations in SciSearch® Peer-reviewed journal Moderate to High – Detailed soil profile descriptions are provided Indirect Input – One conclusion of this paper is that Evidence of Polygenesis of Three Aridisols, Western Mohave Desert, California." Soil Science Society of America Journal, 57, (4), 1041-1050. and soils in a desert environment of southwestern California that is similar in many ways to the Yucca Mountain Region. The paper along with a summary of laboratory methods used for the analyses. The basis for conclusions is clearly stated development of carbonate-free-argillic horizons probably occurred during pluvial periods, whereas calcification occurred during drier periods, and silicification Madison, Wisconsin: thoroughly appears to have been ANL-WIS-MD-000019 REV 01 II-55 April 2004 Table II-7. Sources and Factors Evaluation for Direct Inputs to Diagenesis (Continued) 1. 3. Item Corroborating Item Source Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Soil Science Society of America. TIC: 255602. [DIRS 167625] describes results of a trench study through an alluvial fan sequence and associated soils and draws contemporaneous with both clay illuviation and calcification and, thus, may be related to pedochemical conditions rather than conclusions regarding the distribution of climate. (p. 1049) associated duripans. C25 Not Applicable Humphrey, J.D.; Ransom, K.L.; and Matthews, R.K. 1986. "Early Meteoric Diagenetic Control of Upper Smackover Production, Oaks This paper discusses the effects of early meteoric diagenesis on a grainstone formation. The 20 citations in SciSearch® Technical journal Moderate – Results of studies and some supporting information is provided, but analytical procedures are not provided or discussed. Indirect Input – provides a brief discussion (p. 77-78) of the rate of meteoric diagenesis in carbonate systems in the vadose zone. Field, Louisiana." The American Association of Petroleum Geologists Bulletin, 70, (1), 70-85. Tulsa, Oklahoma: American Association of Petroleum Geologists. paper discusses rates of early meteoric diagenesis, and indicates that intervals that had been stabilized early were less susceptible to Shallow vadose diagenesis can reach completion within 10,000 years, while it may take an order of magnitude longer for the deep vadose zone. TIC: 246098. [DIRS 118461] solution compaction that those intervals retaining significant proportions of unstable mineralogy. C26 Not Applicable Lattman, L. H. 1972. "Relation of Caliche (Calcrete) Horizons to This abstract addresses the formation of Abstract not found in SciSearch® This information is provided only Low – Only the abstract is presented. Basis for conclusion is presumably Indirect Input – This abstract corroborates other better- ANL-WIS-MD-000019 REV 01 II-56 April 2004 Table II-7. Sources and Factors Evaluation for Direct Inputs to Diagenesis (Continued) 1. 3. Item Corroborating Item Source Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Alluvial Fan extensive caliche in abstract on field observations, but documented sources Processes in layers in respect to form and was no documentation is that link diagenetic Southern Nevada." changes in climate presumably provided. processes to climatic Abstracts with conditions. not subject to conditions. Programs-Geological peer-review Society of America, 4, (7), 574. [Boulder, Colorado]: Geological Society of America. TIC: 255828. [DIRS 167813] C27 Not Applicable Lattman, L. H. 1983. "Effect of Caliche on Desert Processes." Chapter 4 Origin and Evolution of Deserts. Wells, S. G.; Haragan, D. R. (eds.). 1st Edition. 101-109. Albuquerque, New Mexico: University of New Mexico Press. This book addresses desert process, and the author of Chapter 4 specifically addresses caliche formation in desert environments. Book not found in SciSearch® Book published by the Committee on Desert and Arid Research of the Southwestern and Rocky Mountain Division of the American Low to Moderate – This chapter summarizes results of studies and a bibliography of cited sources is included. However, no analytical information is provided. Indirect Input – This text corroborates statements by others that the rate of caliche formation depends on climate, parent material, supply of calcium carbonate and topography. It also corroborates statements that TIC: 255700. Associate for formation of caliche [DIRS 167815] the Advancement inhibits infiltration and tends to stabilize the of Science. surface (p. 107-108). C28 Not Applicable Machette, M. N. 1982. "Morphology, Age, and Rate of Accumulation of This abstract addresses the accumulation rate of CaCO3 at various Abstract not found in SciSearch® This information is provided only in abstract Low – Only the abstract is presented. Basis for conclusion is presumably on field observations and Indirect Input – This abstract corroborates accumulation rates cited in better- Pedogneic CaCO3 in Some Calcareous Soils and Pedogenic Calcrete of Southwestern United locations in Utah and New Mexico. form and was presumably not subject to peer-review laboratory analysis of soil samples, but no documentation is provided. documented journal papers. States." GSA Abstracts with ANL-WIS-MD-000019 REV 01 II-57 April 2004 Table II-7. Sources and Factors Evaluation for Direct Inputs to Diagenesis (Continued) 1. 3. Item Corroborating Item Source Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Programs, 14, (4), . Boulder, Colorado: Geological Society of America pp 182-183. TIC: 209942. [DIRS 167814] C29 Not Applicable Palmer, S.N. and Barton, M.E. 1987. "Porosity Reduction, Microfabric and Resultant Lithification This paper addresses the extent of diagenetic change in Jurassic to Recent matrix- Paper not found in SciSearch® This was extracted from a Special Publication Moderate to High – The characteristics of the studied materials are well documented. The methods used are mentioned, but Indirect Input – The results of this paper are used to corroborate the minimal effects of in UK Uncemented Sands." Geological Society Special Publication, 36, 2940. Oxford, United Kingdom: Blackwell Scientific free, uncemented sands in the UK that are thought to have experienced only a relatively small depth (<1km) of burial. However, not further discussed. compaction at shallow burial depths (pp. 32 and 39). Publications. materials are either TIC: 246095. [DIRS 118483] beach material or from stable, shelf areas and are shallow water deposits. C30 Not Applicable Salem, A.M.K.; This paper is Two Peer-reviewed Moderate to High – The Indirect Input – The Abdel-Wahab, A.; and focused on citations in journal paper is focused on paper provides McBride, E.F. 1998. description of SciSearch® description of the geologic examples of the "Diagenesis of sandstones materials. Procedures are occurrence of Shallowly Buried deposited on the briefly described, and ferricrete and silcretes Cratonic Sandstones, Arabian shield in analysis results are that represent incipient Southwest Sinai, Egypt." Sedimentary Geology, 119, ([3-4]), fluvial and shallow- marine environments. provided. silcrete cement rather than normal burial quartz cement, and 311-335. [New York, However, the burial reduction in porosity New York]: Elsevier. depth is suspected by compaction was TIC: 255708. to be no more than about 19 percent 1.5 to 2.5 km, so ANL-WIS-MD-000019 REV 01 II-58 April 2004 Table II-7. Sources and Factors Evaluation for Direct Inputs to Diagenesis (Continued) 1. 3. Item Corroborating Item Source Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status [DIRS 167869] represent shallow burial effects. (pp. 319-331). C31 Not Applicable Yaalon, D.H. 1967. "Factors Affecting the Lithification of Eolianite and Interpretation of Its Environmental Significance in the Coastal Plain of Israel." Journal of Sedimentary Petrology, 37, (4), 1189-1199. Tulsa, This paper addresses the early diagenesis of eolian deposits in a coastal plain setting in southern Israel Citation not found in SciSearch® Peer-reviewed journal Moderate – Sampling and analytical procedures are discussed and results are provided. Indirect Input – This paper provides corroboration for the rate of lithification (p. 1189) and indicates the percent of CaCO3 needed to initiate lithification in coastal sands (p. 1194). Oklahoma: Society of Economic Paleontologists and Mineralogists. TIC: 255600. [DIRS 167622] ANL-WIS-MD-000019 REV 01 II-59 April 2004 4.4.3 Discussion Corroboration of direct input is discussed under four general topics: the time required for diagenesis, the relationships between diagenesis and climate, the role of compaction, and the role of cementation. 4.4.3.1 Time Required for Diagenesis The conditions being justified and the associated direct input is as follows: The time required for complete diagenesis to occur is less than 10,000 years. This is taken from Items Q11 and Q12. Corroboration is given in Items C20, C23, C25, C28, and C31. Direct inputs related to the time required for complete diagenesis come from Krystink (1990 p. 8-1 [DIRS 135295]) (Q11) and from Lattman and Simonberg (1971, p. 277 [DIRS 129306]) (Q12), Krystinik states that cementing minerals can precipitate in quantities sufficient to lithify sand to friable sandstone in less than 5,000 years. Lattman and Simonberg cite several examples of roadcuts and gully banks that are case-hardened in the timeframe of a few tens of years. Corroborating sources include Arakel (1996 p. 226 [DIRS 167623]) (C20), which indicates that rapid maturation of cemented soils profiles can occur within a relatively short time – within the context of the paper, a relatively short time is inferred to be within the time scale of 10,000 years, though a quantitative statement is not made. Humphreys et al. (1986 pp. 76-78 [DIRS [118461]) (C25) provides citations for carbonate systems that indicate that diagenesis in shallow vadose zones subject to meteoric processes may reach completion within a few thousand years, but deeper vadose zone diagenesis may be much more prolonged. Machette (1982 [DIRS 167814]) (C28) and the paper by Eghbal and Southard (1993 p. 170-171 [DIRS 167624]) (C23) provide CaCO3 accumulation rates that range from 0.03 g/cm2 to as great as 0.26 g/cm2 per 1000 years. Yaalon (1967 p.1189 [DIRS 167662]) (C31) indicates that as little as 8 percent CaCO3 is sufficient to initiate lithification. If one assumes a soil density of 1.9 gm/cm3, then only 0.15 gm of CaCO3 is needed to initiate lithification. Depending on the accumulation rate, this could occur on the timescale of less than 1,000 years (assuming an accumulation rate of 0.26 g/cm2 per 1,000 years) to on the order of 5,000 years (assuming an accumulation rate of 0.03 gm/cm2). Thus, the direct inputs are corroborated by other sources. Diagenetic Effect Relationship to Climate The conditions being evaluated and the associated direct input are as follows: SiO2 cementation is not dependent on climatic conditions, but cementation does exhibit distinctive trends that correspond with the ages of the surficial deposits. This is taken from Item Q15. This is corroborated in Items C22, C24 and C26. Accumulation rates are attributable to several climatic scenarios, but climate change was insufficient to significantly decrease the rate of accumulations. This is taken from Item Q15. This is corroborated in Items C23 and C28. ANL-WIS-MD-000019 REV 01 II-60 April 2004 CaCO3 may translocate to greater depths given greater precipitation, and cementation is a reversible effect. This is taken from Item Q15 and corroborated by Items C22 and C26. Because the time frame of interest is 10,000 years, the potential for effects of climate change on shallow diagenesis must be considered. As direct input, Taylor (1986 Chapter 5 [DIRS 102864]) (Q15) indicates silts that formed in alluvium and eolian fines of Holocene to early Pliestocene or late Pliocene age near Yucca Mountain are characterized by distinctive trends in the accumulation of secondary clay, CaCO3, and opaline SiO2 that correspond with the ages of the surficial deposits. However, there is no macro- or micromorphological evidence that suggests that silica cementation occurred under climatic conditions cooler and wetter than those of present climate. In contrast, Taylor also states that accumulation rates of these materials during the Holocene can be attributed to several possible climatic scenarios associated with the Holocene-Pliestocene climate change, but suggest that precipitation has not been a limiting factor, and that climatic change was not sufficient to significantly decrease rate of accumulation. Taylor also suggests that the climatic change was the result of decreases in temperature rather than precipitation. Modeling results discussed by Taylor suggest that increased precipitation in the future may translocate CaCO3 accumulations to greater depths, where precipitation is greater. Taylor also suggests that the cementation process, particularly for CaCO3, is reversible, and that the material can be redissolved and moved deeper into the soil profile. The dependence of the accumulation depth of CaCO3, and the dependence of other diagenetic effects related to chemical changes is corroborated by several sources. Eghbal and Southard (1993 p. 1049 [DIRS 167625]) (C24) suggest that, in the Mojave Desert, development of carbonate-free argilllic horizons probably occurred during pluvial periods, whereas calcification occurred during drier periods. Silicification appears to have been contemporaneous with both clay illuviation and calcification and, thus, may be related to pedochemical conditions rather than to climate. This corroborates the results by Taylor (1986 [102864]) discussed above, and for a similar arid setting. Eghbal and Southard further unequivically state that soils in arid regions are often polygenetically related to climatic variations. This trend for calcification is also corroborated in the abstract by Lattman (1972 [DIRS 167813]) (C26) in the statement that “It is suggested that extensive calcrete layers in southern Nevada formed during and immediately following the onset of pluvial periods which were times of fan aggradation. They were generally destroyed during the interpluvial, which were times of fan stability or degradation.” This statement also tends to suggest that calcification effects may be reversible, whereas silicification may be on-going regardless of the climate state. Further corroboration is gained from Chadwick et al. (1995 [DIRS 167626]) (C22), which documents changes in soil profiles along a transect that reflect cooler and wetter conditions due to elevation changes. However, these serve as a surrogate for change in climate conditions. In particular, they observed that climatic extremes drive pedogenic processes that leave polygenetic imprints on soils of Pliestocene age. In particular, soils that are now dominated by opaline silica, carbonate, and smectite, contain evidence of earlier, more acidic, chemical environments conducive to dissolution of primary carbonate and formation of kaolinite. During interglacial times (i.e., drier and warmer), Chadwick et al. attribute the changes to more eolian activity and less effective moisture combining to decrease the depth of leaching, increase base cations, and modify the soil chemical environment in relict paleosols. ANL-WIS-MD-000019 REV 01 II-61 April 2004 This trend toward increased calcification during pluvial times is corroborated in the accumulation rates noted in the abstract by Machette (1982 [DIRS 167814]) (C28), who indicates that soils <25,000 years old have accumulation rates 2-3 times higher that older soils. This observation is attributed to “less effective precipitation and vegetation cover in Holocene time,” which is due in large part to a drier climate state. The increased accumulation rates of CaCO3, are also noted by Eghbal and Southard (1993 p.170-171 [DIRS 167624]) (C23). Reversibility of cements is cross-corroborated to Krystinik (1990 p. 8-4 [DIRS 135295]) (Q11), who clearly indicates that cementations processes are reversible. Indirect inputs also corroborate this aspect of cementation. Chadwick et al. (1995 [DIRS 167626]) (C22) note that climatic drying at the end of the Pliestocene decreased leaching depth by about 150 cm, and corroborates the changes modeled by Taylor (1986 [DIRS 102864]). This trend for calcification during pluvial periods and decalcification during interpluvial periods is also corroborated in the abstract by Lattman (1972 [DIRS 167813]) (C26) mentioned above, and points to the reversibility of the calcification process at any given location. Compaction during Shallow Diagenesis The conditions being justified and the associated direct input are as follows: Compaction does not become an important factor until the onset of deep burial: This is taken from Item Q11. It is corroborated by Items C21, C29, and C30. The two primary mechanisms for early and shallow diagenetic changes are related to compactions and cementation. Krystinik (1990 p. 8-3 and 8-4 [DIRS 135295]) (Q11) indicates that early diagenesis “begins at or near the depositional interface and entails weathering, compaction, cementation and numerous allied physical, chemical and biochemical processes, at temperature below 50 degrees C”. As direct input, Krystinik notes that “wind-laid sand can be deposited with up to 25-40 percent porosity and that early compaction reduces porosity to 20-30 percent, depending upon sorting”. Krystinik further states that “Beyond increasing capillarity, compaction does not generally become an important factor in diagenesis until the onset of grain deformation and pressure solution during deeper burial diagenesis”. By minimizing compaction, then, the primary means of diagenesis becomes cementation processes. By way of corroborating the role of compaction in early diagenesis, Palmer and Barton (1987 pp. 32 and 39 [DIRS 118483]) (C29) compare similar, uncemented sands of increasing ages and burial depth with porosities. In the first 169 meters of burial, the porosity of the sand decreases from 47.2 to 35.6 percent, but from 169 m to 780 meters, the compaction only decreased the porosity an additional 2 percent, for a total decrease of 13.6 percent. This corroborates Krystinik's assertion of an initial reduction of no more than few percent, followed by minimal effects. The lack of compaction during initial burial is also corroborated by the Sclater-Christie compaction curve given in Baldwin and Butler (1985 Figure 3 DIRS [167871]) (C21). The curve shows that change in porosity during the first 300 m of burial is insignificant, but becomes increasingly more important at greater depths, with changes of up to 50 percent porosity relative to the initial porosities occurring at depths approaching 10 km. However, Baldwin and Butler also caution that sandstones show considerable scatter in solidity-depth values and indicate that ranges in values of 25 percent are common. As a “case-in-point”, the work by Salem et al. ANL-WIS-MD-000019 REV 01 II-62 April 2004 (1998 DIRS 167869]) (C30) on cratonic sandstones indicates that sandstones undergoing burial between 1.5 and 2.5 km exhibited only a 19 percent total porosity loss due to compaction. The results of this work match well with the compaction curves of Baldwin and Butler for a 1 to 2 km burial depth, and further corroborates Krystinik’s assertion that compaction plays only a minor role during the early stages of shallow burial and diagenesis. Cementation during Shallow Diagenesis The conditions being justified, and the associated direct input, are as follows: The net effect of shallow diagenesis is to stabilize the surface environment and decrease the net infiltration rate: This is taken from Item Q14 and is corroborated in Items C20 and C27. Cementation by CaCO3 is not a significant process in rhyolitic tuff due to the lack of carbonate source material: This is taken and cross-corroborated with Items Q11, Q13, and Q15. Cements other than carbonate may develop: This is taken from and cross-corroborated with Items Q11, Q13, Q15, and corroborated by Item C30. Accumulation rates for Yucca Mountain favor SiO2 over CaCO3, which is an accessory cement: This is taken and cross-corroborated with Items Q11, Q13, and Q15. With regard to the role of cementation in diagenesis and its effects, Reeves (1976 [DIRS 104303] Q14) indicates that the net effects of shallow diagenesis and associated cementation is to decrease the net vertical infiltration rate and sites multiple studies to support that assertion. This net reduction in infiltration is corroborated by Lattman (1983, p. 107-108 [DIRS 167815]) (C27) who states, “The formation of caliche inhibits infiltration into a topographic surface. The degree of this inhibition is a function of density and induration of the caliche. Petrocalcic horizons, laminar layers, and case-hardened layers cause the greatest inhibition.” It is also corroborated by Arakel (1996, p. 223 [DIRS 167623]) (C20) who refers to progressive plugging of initial porosity/permeability zones. It should be pointed out that while this holds true for the carbonates, Taylor (1986 [DIRS 102864]) (Q15) indicates that in the YMP soils studied, in the absence of effective precipitation or drainage to remove newly dissolved silica, it is precipitated elsewhere within the calcrete horizon, or CaCO3 preferentially precipitates after opaline silica bonds adjacent soil grains. Taylor notes that this process may occur without necessarily plugging intervening pores spaces. Taylor (1986, Figure 9 [DIRS 102864]) (Q15) indicates that the accumulation rate of CaCO3, while occurring, is significantly less that that for SiO2. This is reflected in statements indicating that carbonate is primarily derived from airborne dust and the opaline SiO2 from in-place weathering of the parent material and that the cementation by opaline SiO2 is common in the study area and that opaline SiO2 accumulation in the soils is favored over that of CaCO3. Taylor also indicates SiO2 cementation is common in the study area, with CaCO3 as an accessory cement. The direct input from Taylor indicating the predominance of SiO2 over carbonate in the soil cements is cross-corroborated with direct input by Lattman (1973, p. 3015 [DIRS 129305]) (Q13). In studies near Las Vegas, Lattman observed that calcium carbonate cementation is not ANL-WIS-MD-000019 REV 01 II-63 April 2004 necessarily a significant cementation process in rhyolitic tuffs due to the lack of carbonate source materials. The above statements by Lattman and Taylor’s observations of the predominance of SiO2 cements mentioned above, also cross-corroborates with statements from Krystinik (1990, p. 8-4 [DIRS 135295]) (Q11) that cements other than carbonate may develop, particularly iron, silica, and aluminum. Yaalon (1967, [DIRS 167622]) (C31) corroborates this by indicating that one of the controlling factors in diagenesis of Eolian sands is the original content of CaCO3. As a corroborative example from indirect input, the presence of cements other than carbonate in arid environments is proposed by Salem et al (1998, pp. 319-331 [DIRS 167869]) (C30). In that particular study, the predominant cements stemming from the generally arid environment were iron and silica. 4.4.4 Data Status and Limitations For qualitative data, the criterion of general agreement has been satisfied. The above literature review and corroboration of the direct input provides an acceptable level of confidence that the data are suitable for their intended use, which is for FEP Screening. The status of the direct inputs for diagenesis evaluated above should be considered as qualified for use within this technical product. No limitations on use of the qualified data are needed. 4.5 SUITABILITY DEMONSTRATION OF DIRECT INPUT FOR FEP 1.5.01.01.0A METEORITE IMPACT The analysis for meteorite impact probability and consequence requires the use of direct input, cited from Technical journals and other non-YMP originated sources, to represent the full range of the possible types and size of meteorites potentially striking the repository within a 10,000-year time frame, and the resulting exhumation and fracturing depths and characteristics. This section provides a justification for use of the meteor-related direct input based on its adequacy and appropriateness for its intended use for FEPS Screening. The general type of information and specific topics being addressed follows: Meteoroid flux entering Earth’s Atmosphere Flux data for a range of meteor masses: Taken from Item Q16 Compositions and Material Properties of Meteoroids Flux data, by meteor type and related densities: Taken from Item Q17 Values for percent of meteor that are of iron composition: Taken from Item Q23 Crater Diameter Distributions and Rates Crater rate distribution based on observed earth cratering: Taken from Item Q19 and Q20 Cratering rate data for the Canadian shield and application to a hypothetical Canadian repository: Taken from Item Q24 ANL-WIS-MD-000019 REV 01 II-64 April 2004 Crater Dimensions as a Function of Meteor Type Results of a model (by others) linking a variety of effects to initial meteor radius, including resulting crate diameters and related consequences: Taken from Item Q22 Depth and Extent of Crater Features Diameters associated with onset of complex cratering: Taken from Items Q19, Q20, and Q24 Crater diameter to depth of effect relationships: Taken from Items Q18, Q21, and Q24 The data being evaluated include Items Q16 through Q24 in Table II-1. The evaluation criteria for quantitative data are applied. Corroboration will be considered acceptable, if “singular” values (e.g., mean velocity or percent by composition) are shown to be within two standard deviations of the mean value, with the mean and deviations developed by equal weighting of reported mean values from each source. In the case of probability distributions or equations based on probability distributions (e.g., mass flux or cratering rates), corroboration will be considered acceptable if the resulting probability distributions fall within 2 orders of magnitude for any given point in the distribution (e.g., for the probability of crater diameter of a given size). 4.5.1 Literature Search A focused literature search was performed to identify past analyses of meteorite impact probabilities for underground facilities (particularly repositories); for current information and studies related to meteorite impact probabilities; for current information and direct input on meteor characteristics; and for information related to crater features and dimensions. The literature search was focused on recent papers and updates, and on information directly relevant and applicable to the analysis. The results of the literature search, using Internet based search engines and the GeoRef® database, and after screening based on titles and abstracts, are given below in Table II-8. 4.5.2 Evaluation of Factors For each of the sources to be used in the evaluation (whether as direct input as data or as indirect input for corroboration), these factors are evaluated in tabular form in Table II-8. ANL-WIS-MD-000019 REV 01 II-65 April 2004 Table II-8. Sources and Factors Evaluation for Direct Inputs to Meteorite Impacts Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others 3. Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Q16 C32, C33, C35, C36, C37, C40, C42, C44 Ceplecha, Z. 1992. "Influx of Interplanetary Bodies onto Earth." Astronomy and Astrophysics, 263, 361-366. New York, New York: Springer- Verlag. TIC: 246784. [DIRS 135242]. This paper represents a compilation of results of studies by others addressing mass flux over a wide range of masses. The paper provides cumulative mass by number of events for meteoroids coming to the earth’s atmosphere. Also provides a means to relate mass to impact velocity at the surface if needed. No prior use for repository design. However, subsequent related papers cite author. Science Citation Index indicates 49 citations. This paper taken from a respected, peer- reviewed journal (Astronomy and Astrophysics). Moderate - Citation to the original sources are provided. Quality of derivation of conclusions regarding consequences is moderate but adequate for intended purpose of the paper, and supporting equations are provided. Does not rely solely on single method to determine flux, such as kinetic energy observations, and thus can be corroborated using multiple flux measurements methods. Direct input — Flux data for a range of meteor masses: Indirect Input — Provides corroborative-use only information for crater radius comparison. Q17 For percent by Type: Q17 (from an independent data set), C40, C43 For densities: Q17 (from an independent data set), C32, C35, C36, C37. C39, C40, C45 Ceplecha, Z. 1994. "Impacts of Meteoroids Larger than 1m into the Earth's Atmosphere." Astronomy and Astrophysics, 286, (3), 967-970. New York, New York: Springer-Verlag. TIC: 246761. [DIRS 135243], Q17 The paper focuses on determining differences in meteor compositions based on differences in atmospheric penetration based on photographed meteors and fireballs. This information is then categorized by type and bulk densities, and types are assigned a percentage basis. Paper is of interest primarily because it provides a distribution of meteors by type for meteoroids with diameters on the order of <1 to 10 m, which is within the range of interest for possible repository damage. No prior use for repository design. Science Citation Index indicates 17 citations. This paper was taken from a respected, peer- reviewed journal (Astronomy and Astrophysics). Moderate – The absence of the presentation of the original information and the process used to “normalize” for classification is lacking. Discussion of methods used to obtain the initial information is not provided. However, paper represents one of the few attempts to categorize small meteoroids by type. Direct input — Flux data, by meteor type and related densities: ANL-WIS-MD-000019 REV 01 II-66 April 2004 Table II-8. Sources and Factors Evaluation for Direct Inputs to Meteorite Impacts (Continued) Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others 3. Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Q18 Q21, Q24 Dence, M.R.; Grieve, R.A.F.; and Robertson, P.B. 1977. "Terrestrial Impact Structures: Principal Characteristics and Energy Considerations." Impact and Explosion Cratering, Planetary and Terrestrial Implications, Proceedings of the Symposium on Planetary Cratering Mechanics, Flagstaff, Arizona, September 13-17, 1976. Roddy, D.J.; Pepin, R.O.; and Merrill, R.B., eds. Pages 247-275. New York, New York: Pergamon Press. TIC: 247237. [DIRS 135253]. This is a seminal work in the area of impact cratering and provides a listing and discussion of development of observed crater characteristics. Paper relates energy release and dissipation in the subsurface, which is a principal property of interest. The effects addressed in this paper have been used in other repository design considerations, and the energy release equations are often cited in other works in the subject area. Science Citation Index indicates 17 citations. This paper was extracted from an edited compendium of related work. The effects addressed in this paper have been used in other repository design considerations and the cratering rate is generally accepted due to its basis on observed features. Moderate – The paper provides a summary of characteristics of craters and respective dimensions and compares cratering effects to those of nuclear testing. No information on procedures or quality control is provided. Direct input — Crater diameter to depth of effect relationships Indirect Input — Provides corroborative- use only information for crater radius related to iron meteors. Q19 Q20, Q24, C32, C35, C4, C42 Grieve, R.F. 1987. "Terrestrial Impact Structures." Annual Review of Earth and Planetary Sciences, 15, 245-269. Palo Alto, California: Annual Reviews. TIC: 246788. [DIRS 135254]. Q19 This is a seminal work in the area of impact cratering and lists observed craters, crater characteristics, and cratering rates. The paper provides relationships of crater diameter to crater depth and provides a cratering rate estimate for large- diameter craters that are generally used in hazard estimates. The effects addressed in this paper have been used in other repository design considerations and are heavily cited in other works in the subject area. Science Citation Index indicates 23 citations. This paper was taken from a peer-reviewed journal. The effects addressed in this paper have been used in other repository design considerations. Moderate - The documentation is somewhat limited, but is generally accepted as reliable and has been updated on a periodic basis. No information on procedures or quality control is provided. Direct Input – Crater rate distribution based on observed earth cratering ANL-WIS-MD-000019 REV 01 II-67 April 2004 Table II-8. Sources and Factors Evaluation for Direct Inputs to Meteorite Impacts (Continued) Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others 3. Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Q20 Q19, Q24, , C32, C35, C40, C42 Grieve, R.; Rupert, J.; and Therriault, A. 1995. "The Record of Terrestrial Impact Cratering." GSA Today, 5, (10), 194196. Boulder, Colorado: Geological Society of America. TIC: 246688. [DIRS 135260] This is an update to the 1987 paper by the primary author. It provides updated cratering information, refines the constants, and addresses the limits for simple and complex cratering The effects addressed in this paper have been used in other repository design considerations and are heavily cited in other works in the subject area. Update to previous paper. Science Citation Index indicates seven citations This paper was taken from a technical journal. Acknowledgment s are given to peer-reviewers on an earlier version of the document. Moderate to High- This paper provides a listing of observed cratering impact structures and their diameters and ages, allowing independent confirmation of the developed distribution. A thorough reference list is also provided. Direct Input – Diameters associated with onset of complex cratering (4 km) (p. 194) Crater rate distribution based on observed earth cratering Q21 Q18, Q24 Grieve, R.A.F. 1998. "Extraterrestrial Impacts on Earth: The Evidence and the Consequences." Meteorites: Flux with Time and Impact Effects. Grady, M.M.; Hutchinson, R.; McCall, G.J.H.; and Rothery, D.A., eds. Geological Society Special Publication No. 140. Pages 105131. London, England: Geological Society. TIC: 254143. [DIRS 163385] This is an update and summary of previous papers and summarizes the results of studies to date, and provides a distinction of the cratering effect data based on craters in sedimentary and crystalline materials. This paper is focused on updating the “state of knowledge” regarding the number of craters, cratering mechanics, shock metamorphism, and effect of impacts on biological evolution. This paper was taken from a compendium addressing flux with time and impact effects. Moderate – This paper is focused on updating the “state of knowledge” and summarizing the corresponding findings, rather than reporting new results of research. An extensive reference list is provided. Direct Input – Crater diameter to depth of effect relationships: Q22 Q16, Q18, Q23, (these Q items are not cross- corroborative back to Q22), C32, C36, Hills, J.G. and Goda, P.M. 1993. "Fragmentation of Small Asteroids in the Atmosphere." The Astronomical Journal, 105, (3), Paper focuses on evaluating effects of small asteroids impacting the Earth. Paper deals with a multitude of related consequences and serves to relate initial meteor No prior use for repository design. Science Citation Index indicates 81 citations. This paper was taken from a peer-reviewed journal. Moderate to High - Los Alamos National Laboratory prepared the work, and the development of the models is well documented and Direct Input — Crater Dimensions as a Function of Meteor Type Figures 16 and 17 provide key meteor radius to crater diameter relationship information. ANL-WIS-MD-000019 REV 01 II-68 April 2004 Table II-8. Sources and Factors Evaluation for Direct Inputs to Meteorite Impacts (Continued) Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others 3. Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status C37, C40 1114-1144. Woodbury, New York: American Institute of Physics. TIC: 246798. [DIRS 135281]. diameters to crater diameters over the range of crater diameters of interest. The paper considers several interrelated physical phenomena to derive resulting crater diameters. supporting equations are provided. No information is provided on quality control or development procedures. Results are presented for a variety of meteor types and for a wide range of velocities, which allows the paper to be corroborated from other multiple sources. Q23 Q23 (independent data set) C34, C37, C39, C43 Shoemaker, E.M. 1983. "Asteroid and Comet Bombardment of the Earth." Annual Review of Earth and Planetary Sciences, 11, 461-494. Palo Alto, California: Annual Reviews. TIC: 246922. [DIRS 135308]. This paper focuses on the roles of asteroids and comet nuclei on the rate of crater formation. Includes a review of astronomic and geologic information and provides citations to support the summaries. This paper is applicable with regard to flux, composition, meteor size– to-crater-diameter relationships, and cratering rate. No prior use for repository design. Science Citation Index indicates 94 citations- This paper was taken from a peer-reviewed journal. Moderate – Sources are fully documented. Assumptions and bases for conclusions are clearly outlined. No information is provided on procedures used or quality control. Direct Input – Values for percent of meteor that are of iron composition: Indirect Input —Provides corroborative only information for crater radius. Q24 Q18, Q19, Q20, Q21, , C32, C35, C40, C42 Wuschke, D.M.; Whitaker, H.H.; Goodwin, B.W.; and Rasmussen, L.R. 1995. Assessment of the Long-Term Risk of a Meteorite Impact on Hypothetical Canadian Nuclear Fuel Waste Disposal Vault Deep in Plutonic Rock. AECL-11014. Pinawa, Manitoba, Canada: Atomic Energy of Canada Limited, Whiteshell This paper is directly applicable as it presents a well-documented evaluation equivalent to the evaluation needed for YMP. The paper provides a detailed analysis of the hazard and risk associated with meteorite impact above an underground repository. Assumptions, spatial relationships, mathematical formulations, and uncertainty analysis are all documented within the Paper was prepared by AECL Research to evaluate risk from meteorite impact on a hypothetical underground repository. Science Citation Index indicates no citations. The paper reports results of a specific technical analysis. No information on prior peer review is available. High –Citations are provided for all sources and uncertainty analyses are provided. Cites non- peer reviewed work. Direct Input – Cratering rate data for the Canadian shield and application to a hypothetical Canadian repository. ANL-WIS-MD-000019 REV 01 II-69 April 2004 Table II-8. Sources and Factors Evaluation for Direct Inputs to Meteorite Impacts (Continued) 3. Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Laboratories. TIC: 221413. [DIRS 129326]. report. C32 Bailey, M.E. and Emel'Yanenko, V.V. 1998. "Cometary Capture and the Nature of the Impactors." Meteorites: Flux with Time and Impact Effects. Grady, M.M.; Hutchison, R.; McCall, G.J.H.; and Technically Adequate – Paper is focused on addressing uncertainty in the number of particular type comets present and uses existing equations and information from others to develop the argument with regard to cratering rates. Paper provides information on diameter distributions, associated cratering rates, and provides input on assumed density of asteriods and comets. No prior use for repository design considerations. Science Citation index indicates 1 citation. Taken from edited and refereed compendium from Geologic Society of London (31 referees, including two who are routinely cited in work of this nature). Low to Moderate – None beyond that provided in paper. Rothery, D.A.; eds. Geological Society Special Publication No. 140. Pages 1117. Bath, England: Geological Society of London. [DIRS 162564] TIC: 254143. Low to Moderate. Provide an independent means to establish meteor diameter distribution and cratering rate. Provides densities. Used primarily as source of corroborative- use-only information for cratering rates. C33 Not Applicable Bland, P.A.; Conway, A.; Smith, T.B.; Berry, F.J.; Swabey, S.E.J.; and Pillinger, C.T. 1998. "Calculating Flux from Meteorite Decay Rates: A Discussion of Problems Encountered in Deciphering a This paper is focused on identifying problems and methodologies for pairing of meteorite fragments. It addresses limitations with application of meteorite information to flux and composition determinations. No prior use for repository design Science Citation Index indicates one citation. This paper was extracted from an edited and refereed compendium of the London Geologic Society (31 referees, including two who are routinely cited in work of Moderate – The paper cites heavily to other related studies and fully documents associated problems, uncertainties, and limitations of its applications. Cites and summarizes previous work of others and thus provides an independent source of information Indirect Input – Provides summary of multiple related flux studies and provides corroborative- use only information for flux evaluation. ANL-WIS-MD-000019 REV 01 II-70 April 2004 Table II-8. Sources and Factors Evaluation for Direct Inputs to Meteorite Impacts (Continued) 3. Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status 10{superscript 5}– this nature). regarding falls to earth. 10{superscript 6} Year Integrated Meteorite Flux at Allan Hills and a New Approach to Pairing." Meteorites: Flux with Time and Impact Effects. Grady, M.M.; Hutchison, R.; McCall, G.J.H.; and Rothery, D.A.; eds. Geological Society Special Publication Mo. 140. Pages 4358. Bath, England: Geological Society of London. TIC: 254143. [DIRS 162563]. C34 Not Applicable Bevan, A.W.R.; Bland, P.A.; and Jull, A.J.T. 1998. "Meteorite Flux on the Nullarbor Region, Australia." Meteorites: Flux with Time and Impact Effects. Grady, M.M.; Hutchison, R.; McCall, G.J.H., and This paper focuses on summarizing meteorite falls in Australia. It is based on collected specimens, and identifies limitations and potential biases of human collections and problems of the sample area are addressed. Addresses mass distribution and No prior use for repository design purposes. Science Citation Index indicates one citation. This paper was extracted from an edited and refereed compendium of Geologic Society of London (31 referees, including two who are routinely cited in work of High – information is well characterized; limitations are fully acknowledged; information from related studies are provided for context; and differing interpretations are considered. Indirect Input – Provides baseline corroborative- use only information for comparison of several meteorite falls with regard to frequency and type. It provides corroborative information for percent of iron meteors. Rothery, D.A.; eds. Geological Society Special Publication No. 140. Pages 5973. Bath, England: Geological Society of London. frequency of meteorite falls, and breaks out the falls on a percentage-by- type basis. this nature). TIC: 254143. [DIRS 162565]. C35 Not Applicable Brown, P.; Spalding, The study is based on use No prior use for This paper was High - Paper is well Indirect Input – This paper ANL-WIS-MD-000019 REV 01 II-71 April 2004 Table II-8. Sources and Factors Evaluation for Direct Inputs to Meteorite Impacts (Continued) 3. Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status R.E.; ReVelle, D.O.; Tagliaferri, E.; and Worden, S.P. 2002. "The Flux of Small Near-Earth Objects Colliding with the Earth." Nature, 420, ([6913]), 294-296. [London, England: Macmillan Journals]. TIC: 254145. [DIRS 162569]. of state-of-the-art U.S. Department of Defense and U.S. Department of Energy space-based systems in geostationary orbits, and represent eight years of collection efforts and 300 samples representing between 60% and 80% earth coverage. The results represent in essence a “whole earth” detection repository design purposes. Paper was published in November 2002, and represents best “direct” measurement of flux into the atmosphere. Paper provides comparison to similar information from related taken from a highly respected peer reviewed journal (Nature). documented and cites many of the authors used for the evaluation. Assumed values are clearly identified. Uncertainty is estimated at less than 30%, which is the least uncertainty documented in studies of this type found during the literature survey. Also clearly states assumptions regarding velocities and assumed represents the most current information of this type available and covers the range of interest with a reasonably large sample set. Used for corroboration of flux and crater rate distribution. Summary equation provided to determine flux rates based on meteoroid diameter and in terms of bolide energy. using state-of-the-art satellite observation. programs. Science Citation densities for meteorites and basis for Study is particularly targeted to the meteor diameters of interest. Index indicates three citations. assumptions. C36 Not Applicable Chapman, C.R. and Paper provides a short No prior use for This paper was Moderate - Basis of influx Indirect Input– This paper Morrison, D. 1994. review of past influx repository taken from a used in analysis of hazard provides a good overall "Impacts on the Earth studies and discusses design. Science highly respected is well documented. corroborative summary of by Asteroids and velocities and densities as Citation Index peer-reviewed Assumed flux and influx information, and Comets: Assessing the Hazard." Nature, 367, (6458), 33-40. well as rates and potential resulting hazards. Paper is focused on determining indicates 65 citations. journal (Nature). justification is provided and uncertainty in assumed values is through Figure 1, links impact interval, diameter, and equivalent yield. It New York, New York: hazard of surface effects provided and stated as also provides several Nature America. from asteroid impact. between a factor of 2 and “singular” events and TIC: 246781. [DIRS 135245] 5. Overly conservative values chosen for determining risk. related probabilities that are corroborative-use-only information. However, the paper is focused on surface effects rather than cratering. C37 Not Applicable Chyba, C.F. 1993. "Explosions of Small Spacewatch Objects in Earth's Atmosphere." Nature, 363, (6431), 701-703. London, United Paper provides a short review of past influx studies and discusses velocities, densities, and probabilities of impact. Paper presents results of direct observation of No prior use for repository design. Cited by later papers and compared to updated information or This paper was taken from a highly respected peer-reviewed journal (Nature). Moderate to High – The paper is based on original information obtained from an on-going observation program and compared to results of similar programs. No information Indirect Input –Paper provides corroborative information on observed velocities and influx of small-diameter objects, which are of particular interest. Provides Kingdom: Macmillan meteors and impact information on procedures or quality corroborative information ANL-WIS-MD-000019 REV 01 II-72 April 2004 Table II-8. Sources and Factors Evaluation for Direct Inputs to Meteorite Impacts (Continued) 3. Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Journals. TIC: 246762. [DIRS 135248]. probabilities are discussed. obtained by independent means. Science Citation Index indicates 13 control is provided. on percent irons and densities, and provides corroborative information for determining resulting crater radius. citations C38 Not Applicable Hartmann, W.K. 1966. Terrestrial and Lunar Flux of Large Meteorites Through Solar System History. Publication No. 3. The paper deals directly with earth cratering rates for larger scale (>1-km) craters. Not used for repository design. Science Citation Index indicates no citations. Author No information on peer review process. Low to Moderate - Paper published by Arizona Statue University’s Center for Meteorite Studies and therefore, considered reliable within context of Indirect Input — This paper provides an initial baseline, but due to dated information and limited number of observations should not be given equal Tempe, Arizona: was cited for the the time of publishing. weight to papers of a Arizona State WIPP meteorite However, this paper is similar nature. This University, Center for analysis. dated and, therefore, source is not further Meteorite Studies. technical accuracy is considered in this TIC: 254144. [DIRS 162567]. limited. It provides a glimpse of early estimated cratering rates based on evaluation. initial observations of earth and lunar cratering counts. C39 Not Applicable Hills, J.G. and Goda, Addresses additional No prior use for This paper was Moderate to High – Indirect Input – The P.M. 1998. "Damage variables for considering repository taken from a Documentation is similar results of the paper justify from the Impact of effects of meteor impacts. design. Science peer -reviewed to that provided in the use of bounding Small Asteroids." Planetary and Space Science, 46, (2-3), This is a follow-on paper that addresses the potential for variation of Citation Index indicates three citations. journal. preceding paper. conditions by establishing a “worst case” condition for angle of entry. It is not 219-229. Oxford, impact effects due to further considered in this United Kingdom: initial entry angle. It is an analysis, but is used to Elsevier. expansion of the support vertical entry as a TIC: 246675. [DIRS 135291]. preceding paper by the same authors. bounding consideration. C40 Not Applicable Hughes, D.W. 1998. "The Mass Distribution of Crater- Producing Bodies." Meteorites: Flux with Time and Impact Effects. Geological Society Special Paper addresses three factors that define basic relationships of meteor flux to cratering rates. The analysis is applicable to very large diameter meteoroids. The paper uses a subset of highly No prior use in repository design. Science Citation Index indicates five citations. This paper was extracted from an edited and refereed compendium of the London Geologic Society of London (31 Moderate - Paper provides a good summary of preceding work by others and performs an evaluation of these various sets and range of equations. This paper addresses three Indirect Input – This paper primarily addresses large diameter meteors, which end up being excluded from consideration on a probability basis. However, the paper does provide corroborative–use ANL-WIS-MD-000019 REV 01 II-73 April 2004 Table II-8. Sources and Factors Evaluation for Direct Inputs to Meteorite Impacts (Continued) 3. Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Publication No. 140. defensible cratering referees, interrelated factors, the only information for influx, Grady, M.M.; information to perform an including two crater rate equation, the cratering rate, and meteor Hutchison, R.; evaluation of various who are routinely energy diameter equation, properties. McCall, G.J.H.; and equations and related cited in work of and the mass distribution Rothery, D.A.; eds. uncertainties. this nature). equation. No Pages 31-42. Bath, documentation on England: Geological procedures or quality Society of London. control is provided. TIC: 254143. [DIRS 162562]. C41 Not Applicable Marsden, B.G. and Steel, D.I. 1994. "Warning Times and Impact Probabilities for Long-Period Comets." Hazards Due to Comets and Asteroids. Gehrels, T., ed. 221-237. Tucson, Arizona: University of Arizona Press. TIC: 246879. [DIRS 129308] This -paper directly addresses probability of intersection with earth and is, therefore, directly applicable. Paper focuses on determining the probability of impact from long period comets under varying sets of assumption regarding orbital characteristics. The sources used in this analysis are well documented within the paper and the study addresses 411 observed No prior use for repository design. Science Citation Index indicates nine citations. This paper was extracted from an edited compendium of related papers. Moderate to High –Paper documents both the theory and practical application used to develop the probabilities of intersection. No documentation on procedures or quality control is provided. Indirect Input — The paper is useful in defining the range of probabilities of long period comets over a range of assumptions regarding orbital characteristics and supports excluding impact from long period comets based on individual and mean impact probabilities. No further consideration in this evaluation long period comets. ANL-WIS-MD-000019 REV 01 II-74 April 2004 Table II-8. Sources and Factors Evaluation for Direct Inputs to Meteorite Impacts (Continued) 3. Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status C42 Not Applicable Neukum, G. and Ivanov, B.A. 1994. "Crater Size Distributions and Impact Probabilities on Earth from Lunar, Terrestrial-Planet, and Asteroid Cratering Data." Hazards Due to Comets and Asteroids. Gehrels, This paper is directly applicable, and provides an alternative method (i.e., use of lunar cratering and from other planets) to evaluate cratering on Earth. Paper focuses on determining cratering rates for from lunar, terrestrial planet, and asteroid cratering. The sources and discussion of No prior use for repository design. Science Citation Index indicates 53 citations. This paper was extracted from an edited compendium of related papers. Moderate to High – The methodology and assumptions used are fully documented within the paper. No information on quality control or procedures for the selection of craters is provided. Indirect Input — This paper provides an independent evaluation based on lunar cratering rates that can be used as an upper bound to corroborate flux and/or cratering rates based on earth observations or derived from flux information. T., ed. 359-416. Tucson, Arizona: The University of Arizona Press. alternate interpretations are fully documented. No original information is developed in this paper. TIC: 246879. [DIRS 121510]. C43 Not Applicable Richardson, J. and Bedient, J. 2001. "Frequently Asked Questions (FAQ) About Fireballs and Meteorite Dropping Fireballs." [Geneseo, New York]: American Meteor Society. Accessed April 22, 2003. TIC: 254120. [DIRS 162571]. This citation provides a range of information regarding general meteor properties and characteristics. The source, while not strictly scientific, serves as a general clearinghouse of information for use by the public. No prior use for repository design, and no information regarding review process. Science Citation Index indicates no citations. Not published – downloaded from an Internet site. This citation is to the home page of the American Meteor Society, a non-profit scientific organization established to encourage and support the research activities of both amateur and Low to Moderate – The FAQ page states that “ . . . all of the numbers are estimates, and subject to revision as our knowledge level increases. We have attempted to select the most representative values for each”. . There is no information on the extent of literature search or procedures used to derive the stated values. Citations regarding the stated properties are absent within the text, but Indirect Input — This cite provides corroborative- use-only information from a reliable Internet cite of a recognized scientific organization. Sufficiently reliable to use as corroborative source for meteor characteristics and addresses the possible range in values. professional astronomers a list of supporting references is provided. The stated values appear to have been based on generally reliable sources and agree in general with information from sources evaluated herein ANL-WIS-MD-000019 REV 01 II-75 April 2004 Table II-8. Sources and Factors Evaluation for Direct Inputs to Meteorite Impacts (Continued) 3. Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status C44 Not Applicable Solomon, K.A.; Erdmann, R.C.; and Okrent, D. 1975. "Estimate of the Hazards to a Nuclear Reactor from the Random Impact of Meteorites." Nuclear Technology, 25, 6871. La Grange Park, Illinois: American This paper is an early effort at linking meteorite impact damage via kinetic energy to the probability of impact for a nuclear facility. This paper focuses on probability estimates for meteorite impacts for nuclear reactors and takes into account blast effects from Used in relation to nuclear siting programs, including preclosure external event hazard evaluation for YMP from meteorites. No information on This paper was taken from a journal sponsored by the American Nuclear Society. The type of review process used is unknown. Low to Moderate – The paper documents the key assumptions used and outlines the mathematics used to determine the probability. However, the basis for developing the damage-to-energy assumption and the basis supporting the mass influx, while cited, is not Indirect Input– This paper was previously used as the support for eliminating meteorite impact as a preclosure hazard at YMP. It provides the probability of small-body impacts and uses differing sources for flux. Therefore, it provides a corroborative estimate of Nuclear Society. “near misses”. The paper verification is discussed. The the probability of impact TIC: 241714. [DIRS 103697]. is primarily focused on probability of a given size, rather than on consequence. provided. Science Citation Index indicates two citations. assessment in meteorite hazard dates to 1968, and there has been significant progress since that time. No information is provided for a range of various meteorite mass. on procedures or quality control associated with the cited sources of information. C45 Not Applicable Stuart, J.S. 2001. "A Near-Earth Asteroid Population Estimate from the LINEAR Survey." Science, 294, (5547), 16911693. Washington, D.C.: American Association for the Advancement of Science. TIC: 254146. This paper reports results of a detailed near-space survey (LINEAR). The scope of the survey is described, as are biases and limitations of the study. Paper provides an estimate of flux of small- to medium- size, near- earth objects based on physical observation and represents current results. No prior use in repository design. Given the currency of the report, use by others is limited. Science Citation Index indicates seven citations. This paper was extracted from highly respected peer-reviewed journal (Science). High – This paper provides a detailed description of methodologies and assumptions used in calculating the flux distribution. The sample size used to derive a flux is approximately an order of magnitude larger than used for predecessor programs Indirect Input – This paper is of moderate use in that the magnitude observations are not linked to diameter of meteoroids and is not further evaluated. LINEAR is cited by Brown et al. and supports work of Bailey and Emel’Yanenko. [DIRS 162568]. C46 Not Applicable Zolensky, M. 1998. "The Flux of Meteorites to Antarctica." Meteorites: Flux with Time and Impact Effects. Geological This paper is focused on the summary of meteorite falls in Antarctica. The results are based on collected specimens, and the limitations and potential biases of human No prior use for repository design purposes. Science Citation Index indicates one citation. Paper was extracted from an edited and refereed compendium of the London Geologic Society High – The study methods are well characterized and limitations are fully acknowledged. Related studies are discussed for context, and differing interpretations are Indirect Input - Provides baseline for comparison of several meteorite falls with regard to frequency and type. Not further considered in this evaluation. ANL-WIS-MD-000019 REV 01 II-76 April 2004 Table II-8. Sources and Factors Evaluation for Direct Inputs to Meteorite Impacts (Continued) 3. Item Corroborating Items Source 1. Demonstrates Properties of Interest 2. Prior Use by Others Type of Publication and Review 4. Extent and Reliability of Documentation 5. Proposed Input Status Society Special collections, and problems (31 referees, considered. Publication No. 140. of sample area are all including two Grady, M.M.; addressed. It also who are routinely Hutchison, R.; addresses mass cited in work of McCall, G.J.H., and distribution and frequency this nature). Rothery, D.A.; eds. of meteorite falls, and Pages 93-104. Bath, breaks out the falls on a England: Geological percentage-by-type basis. Society of London. TIC: 254143. [DIRS 162566]. ANL-WIS-MD-000019 REV 01 II-77 April 2004 4.5.3 Discussion The evaluation presented in this section compares direct input used as data to corroborating-use only information (indirect input) also taken from peer-reviewed journal papers or edited and refereed compendiums of relevant work. Comparisons of the information sets are shown by graphical representation, or are provided in tabular format, to allow ready comparison of the cited values from the various sources. Corroboration is considered achieved if a cited “singular” value (e.g., a cited percent by composition or density) is shown to be within one standard deviation of the mean value of the cited sources. In the case of distributions or distributions generated from equations (e.g., mass flux or cratering rates), corroboration is considered acceptable if the resulting distributions fall within one order of magnitude of the median for any given point in the distribution (e.g., ± one standard deviation of the median value for the probability of crater diameter of a given size). For information addressing meteor radius-to-crater radius relationships and crater diameter-to-depth of cratering effects, agreement within a factor of two is considered adequate for intended use. Consistent with the intended use for FEP screening, latitude in applying these criteria was taken in two instances. The first instance was for direct input representing percent by type and density. No exclusion of information was made for points falling more than one standard deviation from the mean. The exclusion would have affected at most a few of the points in each of the information sets, and retention helps reflect the entire range in reported values. The second instance occurred with regard to the direct input extracted from Hills and Goda (1993 [DIRS 135281]) (Q22) for the meteor radius-to-crater radius relationships. The above-stated criteria did not seem applicable in a strict sense. Rather, examples and ranges or limits identified in the cited literature were plotted as “corroborative-use-only”, where feasible, against the curves taken from Hills and Goda (1993 [DIRS 135281]) (Q22). A standard of “reasonable agreement” in trends between the corroborative-use-only information was applied rather than application of a statistical basis because a point-by-point comparison was not feasible due to differing assumptions and basis of calculation. In some instances, the comparison is based on other figures provided in Hills and Goda (1993 [DIRS 135281]) (Q22) that are not part of the direct input being evaluated. The inference is that if individual phenomena and processes (i.e., fragmentation and ablation) agree between the cited sources and Hills and Goda (1993 [DIRS 135281]) (Q22), then this supports the validity of the resultant cratering relationships that depend in part on those phenomena and processes. Because the data comes from a variety of sources, manipulation of the data was needed to provide direct comparison. Accordingly, supporting spreadsheets showing the calculations are provided. 4.5.3.1 Meteoroid Flux Entering Earth’s Atmosphere The data being justified in this section addresses: Flux data for a range of meteor masses. This direct information is taken from Item Q16, and is corroborated using other multiple sources including Items C32, C33, C35, C36, C37, C40, C42, and C44. ANL-WIS-MD-000019 REV 01 II-78 April 2004 The data from Ceplecha (1992, p. 362 and Figure 1 [DIRS 135242]) (Q16) is used as direct input; all other listed sources are used for corroboration only. The basis for selecting Ceplecha as direct input is discussed below. Figure II-1 of this attachment provides a comparison of meteoroid influx information from multiple sources. Flux information presented by Ceplecha (1992, Figure 1 [DIRS 135242]) (Q16) and corroborated by Bland et al. (1998, Figure 1 [DIRS 162563]) (C33); Brown et al. (2002, Figure 4 [DIRS 162569]) (C35); Neukum and Ivanov (1994, Table IV [DIRS 121510]) (C42); and Solomon (1975, Table I [DIRS 103697]) (C44) are of particular interest due to the completeness, range of mass considered, and varying methods of determination. The flux distribution for these sources is noted on Figure II-1 by the symbols with connecting lines. The information in Table II-9 has been grouped by diameter size to allow ease in comparing the relative cumulative number of events. The work by Ceplecha (1992 [DIRS 135242]) (Q16) is a compilation of the results of works of others and overlaps the corroborative work by Bland et al. (1998 [DIRS 162563]) (C33) by using common sources of information. The two works are based on direct observation of lunar microcraters and space probes, observations of the Spacewatch Telescope program, and by photographs of earth-crossing asteroids. In the case of Ceplecha (1992 [DIRS 135242]) (Q16), however, the full range of flux for all masses is extended by the use of additional information garnered from space probes, radar-tracked meteors, and photographed and television-tracked meteors, all as identified in Ceplecha 1992 (Table 1 [DIRS 135242]) (Q16). In the corroborative case of Brown et al. (2002 [DIRS 162569]) (C35), the results are independent from work of others, and the work was derived from observations using geostationary satellites monitored by the U.S. Department of Defense and DOE. The corroborative information from Neukum and Ivanov 1994 (Table IV [DIRS 121510]) (C42) is based on lunar cratering and, using the stated equivalent energy release, is directly comparable to that of Brown et al. (2002 [DIRS 162569]) (C35). In the case of Solomon (1975 [DIRS 103697]) (C44), the corroborative distribution was cited as being based on “historical evidence as well as current information on meteorite crashes” -with “current” being circa 1968. However, the flux matches reasonably well with information circa 2001. Some mathematical manipulation of the data from the various sources was required to allow direct comparison between direct and indirect data sources. The numerical manipulations needed to convert to equivalent units for comparison along with additional supporting data used to construct Figure II-1 are presented in Table II-10. In the case of Ceplecha (1992 [DIRS 135242]) (Q16) and the corroborative work by Bland et al. (1998 [DIRS 162563]) (C33), points were selected manually from the referenced figures. These papers provide information in terms of number of events by mass. To convert to equivalent diameters, a spherical body of density 3,000 kg/m3 was assumed, and appropriate unit conversions were performed. The assumed density was based on the conversion made in Brown et al. (2002 [DIRS 162569]) (C35) which used the stated density. The graph for Brown et al. (2002 [DIRS 162569]) (C35) was generated from Equation 3 of that paper and checked for internal consistency against Figure 4 of the same paper The corroborative flux from Neukum and Ivanov (1994 [DIRS 121510]) (C42) was extracted directly from their Table IV, with the time between events converted to frequency per year. ANL-WIS-MD-000019 REV 01 II-79 April 2004 For Solomon (1975 [DIRS 103697]) (C44), the corroborative graph was generated by converting the mass intervals to equivalent diameters, and then the number of events of a given size or larger were summed to get the cumulative number of events for a given mass or larger. Other corroborative information is also shown on Figure II-1 as symbols without associated lines. This information was taken from peer-reviewed journal papers, but the source of the cited information was not provided, the source of the information was not transparent, or the information covered only a limited range. Other corroborative-use-only information is taken from studies cited by Bland et al. (1998, Figure 5 [DIRS 162563]) (C33). Results from Blank et al. overlap with that shown on Figure 1 of the same paper, and provides estimates of flux based on meteorite fall studies from New Mexico and Australia. The author fully discusses the limitations of such estimates due to inherent limitations in sample collection and meteorite pairing. It also covers only a minimal range of small diameters. Additionally, for comparison purposes, the reported flux had to be scaled upwards by two orders of magnitude to represent whole-earth influx. Chapman and Morrison (1994, Figure 1 [DIRS 135245]) (C36) is also a source of corroborative- use only information. In this case, the authors clarify the use of an average total impact flux from a single author (p. 34) and clearly indicate that they have not addressed the influx for objects in the <50-m diameter range, which is within the range of interest for the screening analysis. They cite uncertainty as a factor of 2 for objects >0.5 km, and a factor of 5 for smaller objects capable of doing damage (i.e., inferred to mean surface effects rather than cratering). Furthermore, the method of acquisition is not transparent (though it is stated to have been based on work by Shoemaker et al., which is largely photographic). Corroborative-use-only information based on Hughes (1998, Table 2 [DIRS 162562]) (C40) cites work by others, in particular it cites to previous work after, Opik (1976) (C46). The nature of acquisition is not discussed. The 1976 publishing date for Opik suggests that the work may be dated regardless of the methodology used for acquisition. Accordingly, the information is treated as corroborative-use only. Hughes (1998, p. 37 [DIRS 162562]) (C40) also references two other point values from work by others. These are shown on Figure II-1. They represent only single-point values and are not suitable for evaluation as influx distributions. Additionally, Hughes’ focus is on large-scale cratering (i.e., several km), which is not the primary focus of the screening analysis, but does address a portion of the flux distributions. Work by C46b, Bailey and Emel’Yanenko (1998 [DIRS 162564], provides an assumed cumulative diameter distribution given in the form of an equation (Equation 3 of the cited paper), without providing justification for its assumption beyond previous work done by Bailey. Additionally, application of the equation is for the total distribution of near-earth asteroids, and does not specifically address the influx of those actually intercepting the earth. However, a mean probability value is given. For corroborative-use only, this mean value was applied to the number of asteroids of a given diameter to provide a number of asteroid events per year. Some support for the assumed equation comes from Stuart (2001 [DIRS 162568]) (C45), wherein the estimate of the total number of Near Earth Asteroids of 1-km diameter or greater is placed at 1227 with an uncertainty range of –90 to +170 from the stated value. This agrees well with Bailey’s assumed values of 1,500. Stuart also cites other authors that place the cumulative number as low as 750 ±150. ANL-WIS-MD-000019 REV 01 II-80 April 2004 The direct input for the meteor analysis, and the information from the corroborative papers, are summarized in Table II-9. Numeric manipulations of that information, plus information from the other remaining corroborative papers, are shown in Table II-10. Figure II-1 provides a plot of all the corroborative information and corresponds with information in Table II-10. The evaluation criteria as previous discussed, allows acceptance if, for any given diameter, the reported values fall within one order of magnitude of the median value. As can be seen from Table II-9, and also by inspection of Figure II-1, the distribution from Ceplecha (1992 [DIRS 135242]) (Q16) satisfies those criteria and the total range of values in the cumulative events does not exceed two orders of magnitude. ANL-WIS-MD-000019 REV 01 II-81 April 2004 ANL-WIS-MD-000019 REV 01II-82April 2004Flux of Meteoroids to Earth1 E-10 1 E-09 1 E-08 1 E-07 1 E-06 1 E-05 1 E-04 1 E-03 1 E-02 1 E-01 1 E+00 1 E+01 1 E+02 1 E+03 1 E+04 1 E+05 1 E+06 1 E+07 1 E+08 1 E+09 1 E+10 1 E-04 1 E-03 1 E-02 1 E-011 E+001 E+011 E+021 E+031 E+041 E+05Diameter of Meteroids (m) ((t) N (Cumulative Number of Events Per Year of Given Diameter or Greater) for Earth Ceplecha (1992 [135242]) Bland et al. (1998, Figure 1: afterothers [162563]) Brown et al. (2002. [162569]) Neukum and Ivanov (1994, fromlunar cratering [121510] Solomon (1975, Table I [103697]) Bailey and Emel'Yanenko (1998[162564]) Bland et al. (1998, Figure 5, afterZolensky for Roosevelt Co., NM[162563]) Bland et al.(1998, Figure 5, Nullabor [162563]) Bland et al. (1998, Figure 5, afterHalliday [162563]) Chapman and Morrison 1994[135245] Chyba (1993, p. 701 point values[[135248]) Hughes (1998, after Opik 1976[162562]) Hughes (1998, point values fromShoemaker and from Kresak[162562]) Note:[(XXXXXX] in legend denotes DIRS numbersFigure II-1. Influx of Meteoroids to Earth Table II-9. Meteoroid Influx Information DIRECT INPUT CORROBORATIVE INFORMATION Ceplecha (1992, Figure 1 DIRS 135242], Q16) Bland et al. (1998, Figure 1 [DIRS 162563, C33]) Brown et al. (2002, Figure 4 [DIRS 162569], C35) Neukum and Ivanov (1994, Table IV [DIRS 121510], C42) Solomon (1975, Table I [DIRS 103697], C44) Cumulative Cumulative Cumulative Cumulative Cumulative D (meters) Number of Events (N) Per Year- D (meters) Number of Events (N) Per Year- D (meters) Number of Events (N) Per Year- D (meters) Number of Events (N) Per Year- D (meters) Number of Events (N) Per Year- Whole Earth Whole Earth Whole Earth Whole Earth Whole Earth 4.6E-06 3.2E+17 2.1E-05 1.0E+17 9.5E-05 1.0E+16 4.3E-04 3.2E+13 1.0E-03 4.7E+09 5.0E-03 6.0E+07 9.1E-03 3.2E+05 1.0E-02 9.3E+06 2.0E-02 1.4E+06 4.2E-02 3.2E+05 4.2E-02 1.0E+04 5.0E-02 1.2E+05 8.9E-02 1.0E+05 1.0E-01 1.9E+04 8.6E-02 3.4E+03 1.9E-01 1.6E+04 1.9E-01 1.0E+03 2.0E-01 2.9E+03 1.60E-01 3.7E+02 1.8E-01 1.1E+03 4.1E-01 1.0E+04 5.0E-01 2.4E+02 3.9E-01 4.3E+02 8.7E-01 1.6E+03 8.4E-01 1.1E+02 1.9E+00 6.3E+02 1.0E+00 3.7E+01 1.8E+00 8.7E+00 2.0E+00 5.7E+00 2.10E+00 4.1E+00 4.0E+00 1.0E+02 3.8E+00 1.4E+00 5.0E+00 4.8E-01 8.5E+00 1.0E+01 8.2E+00 4.0E-01- 1.0E+01 7.4E-02 1.8E+01 -1.0E-01 1.8E+01 1.0E+00 1.8E+01 8.3E-02- 3.9E+01 1.0E-02 2.5E+01 6.2E-03 3.8E+01 1.5E-02- 5.0E+01 9.6E-04 3.50E+01 6.3E-04 8.3E+01 1.0E-03 8.3E+01 3.2E-03 8.0E+01 3.9E-03- 1.8E+02 1.0E-04 1.0E+02 1.5E-04 1.92E+02 9.1E-06 1.7E+02 8.0E-04- 2.5E+02 1.2E-05 3.8E+02 1.0E-05 3.8E+02 3.2E-05 4.21E+02 3.9E-06 3.7E+02 1.7E-04- 8.1E+02 3.2E-06 5.0E+02 1.9E-06 7.8E+02 3.8E-05- 1.0E+03 2.9E-07 9.22E+02 1.9E-06 1.7E+03 1.0E-06 1.7E+03 1.0E-06 1.7E+03 1.4E-05- 3.7E+03 1.0E-07 2.60E+03 2.2E-07 3.6E+03 1.4E-06- 7.9E+03 3.2E-08 7.9E+03 1.0E-07 5.70E+03 3.7E-08 7.7E+03 2.8E-07 1.25E+04 6.6E-09 1.98E+04 3.2E-09 1.6E+04 5.2E-08 ANL-WIS-MD-000019 REV 01 II-83 April 2004 ANL-WIS-MD-000019 REV 01 II-84 April 2004 Table II-10. Spreadsheet Showing Numerical Manipulations of Information from Journal Papers Direct Input Ceplecha 1992, Figure 1 [DIRS 135242], Q17 Rows: A B C D E F G H FORMULAS (Given) POWER(10, A6) POWER(10,H6) (Assumed) B6/D6 E6*0.75/PI() F6^(1/3)*2 (Given) Log Mass (kg) Mass (kg) Number of Events Per Year Whole Earth Density (kg/m3) Volume (m3) R3 (m3) D (meters) Log N -1 1.0E-01 3.2E+05 3000 3.3E-05 8.0E-06 4.0E-02 5.5 0 1.0E+00 1.0E+05 3000 3.3E-04 8.0E-05 8.6E-02 5.0 1 1.0E+01 1.6E+04 3000 3.3E-03 8.0E-04 1.9E-01 4.2 2 1.0E+02 1.0E+04 3000 3.3E-02 8.0E-03 4.0E-01 4.0 3 1.0E+03 1.6E+03 3000 3.3E-01 8.0E-02 8.6E-01 3.2 4 1.0E+04 6.3E+02 3000 3.3E+00 8.0E-01 1.9E+00 2.8 5 1.0E+05 1.0E+02 3000 3.3E+01 8.0E+00 4.0E+00 2.0 6 1.0E+06 1.0E+01 3000 3.3E+02 8.0E+01 8.6E+00 1.0 7 1.0E+07 1.0E-01 3000 3.3E+03 8.0E+02 1.9E+01 -1.0 8 1.0E+08 1.0E-02 3000 3.3E+04 8.0E+03 4.0E+01 -2.0 9 1.0E+09 1.0E-03 3000 3.3E+05 8.0E+04 8.6E+01 -3.0 10 1.0E+10 1.0E-04 3000 3.3E+06 8.0E+05 1.9E+02 -4.0 11 1.0E+11 1.0E-05 3000 3.3E+07 8.0E+06 4.0E+02 -5.0 12 1.0E+12 3.2E-06 3000 3.3E+08 8.0E+07 8.6E+02 -5.5 13 1.0E+13 1.0E-06 3000 3.3E+09 8.0E+08 1.9E+03 -6.0 14 1.0E+14 1.0E-07 3000 3.3E+10 8.0E+09 4.0E+03 -7.0 15 1.0E+15 3.2E-08 3000 3.3E+11 8.0E+10 8.6E+03 -7.5 ANL-WIS-MD-000019 REV 01 II-85 April 2004 Table II-10. Spreadsheet Showing Numerical Manipulations of Information from Journal Papers (Continued) Corroborative Information (Continued) Bland et al. 1998, Figure 1 [DIRS 162563], C33 Rows A B C D E F G H For0mulas (Given) POWER(10,A35)/1 000 POWER(10,H35) 3000 B35/D35 E35*0.75/PI() F35^(1/3)*2 (Given) Log Mass (g) Mass (kg) Number of Events Per Year Whole Earth Density (kg/m3) Volume (m3) R3 D (meters) Log N -10 1.0E-13 3.2E+17 3000 3.3E-17 8.0E-18 4.0E-06 17.5 -8 1.0E-11 1.0E+17 3000 3.3E-15 8.0E-16 1.9E-05 17.0 -6 1.0E-09 1.0E+16 3000 3.3E-13 8.0E-14 8.6E-05 16.0 -4 1.0E-07 3.2E+13 3000 3.3E-11 8.0E-12 4.0E-04 13.5 0 1.0E-03 3.2E+05 3000 3.3E-07 8.0E-08 8.6E-03 5.5 2 1.0E-01 1.0E+04 3000 3.3E-05 8.0E-06 4.0E-02 4.0 4 1.0E+01 1.0E+03 3000 3.3E-03 8.0E-04 1.9E-01 3.0 10 1.0E+07 1.0E+00 3000 3.3E+03 8.0E+02 1.9E+01 0.0 12 1.0E+09 3.2E-03 3000 3.3E+05 8.0E+04 8.6E+01 -2.5 14 1.0E+11 3.2E-05 3000 3.3E+07 8.0E+06 4.0E+02 -4.5 16 1.0E+13 1.0E-06 3000 3.3E+09 8.0E+08 1.9E+03 -6.0 18 1.0E+15 1.0E-07 3000 3.3E+11 8.0E+10 8.6E+03 -7.0 ANL-WIS-MD-000019 REV 01 II-86 April 2004 Table II-10. Spreadsheet Showing Numerical Manipulations of Information from Journal Papers (Continued) Corroborative Information (Continued) Brown et al. 2002 (Equation 3, Figure 4) [DIRS 162569], C35 Cumulative diameter distribution equation where: c = 1.568, and d = 2.70 log N = c -d log D D = diameter in meters Rows: A B C D E Formulas: E60/1000 2.7*Log(E60) 1.568-B60 POWER(10,C60) (Given) Events Per Year Diameter (N) Diameter (D) (km) d log D c-dlogD Whole Earth (meters) 0.000001 -8.10 9.7 4.7E+09 1.0E-03 0.000005 -6.21 7.8 6.0E+07 5.0E-03 0.00001 -5.40 7.0 9.3E+06 1.0E-02 0.00002 -4.59 6.2 1.4E+06 2.0E-02 0.00005 -3.51 5.1 1.2E+05 5.0E-02 0.0001 -2.70 4.3 1.9E+04 1.0E-01 0.0002 -1.89 3.5 2.9E+03 2.0E-01 0.0005 -0.81 2.4 2.4E+02 5.0E-01 0.001 0.00 1.6 3.7E+01 1.0E+00 0.002 0.81 0.8 5.7E+00 2.0E+00 0.005 1.89 -0.3 4.8E-01 5.0E+00 0.01 2.70 -1.1 7.4E-02 1.0E+01 0.025 3.77 -2.2 6.2E-03 2.5E+01 0.05 4.59 -3.0 9.6E-04 5.0E+01 0.1 5.40 -3.8 1.5E-04 1.0E+02 0.25 6.47 -4.9 1.2E-05 2.5E+02 0.5 7.29 -5.7 1.9E-06 5.0E+02 1 8.1 -6.532 2.9E-07 1.0E+03 ANL-WIS-MD-000019 REV 01 II-87 April 2004 Table II-10. Spreadsheet Showing Numerical Manipulations of Information from Journal Papers (Continued) Corroborative Information (Continued) Neukum and Ivanov 1994 (Table IV) [DIRS 121510], C42 Rows A B C D Formulas (Given) 1/A88 Given (D) LOG(B88) Time Interval (yr) Number of Events Per Year Whole Earth Diameter (D) of Meteor (meters) Log N 2.7E-03 3.7E+02 1.6E-01 2.6 2.4E-01 4.1E+00 2.1E+00 0.6 1.6E+03 6.3E-04 3.5E+01 -3.2 1.0E+05 9.1E-06 1.9E+02 -5.0 2.6E+05 3.9E-06 4.2E+02 -5.4 5.3E+05 1.9E-06 9.2E+02 -5.7 4.5E+06 2.2E-07 2.6E+03 -6.7 2.7E+07 3.7E-08 5.7E+03 -7.4 1.5E+08 6.6E-09 1.3E+04 -8.2 3.1E+08 3.2E-09 2.0E+04 -8.5 ANL-WIS-MD-000019 REV 01 II-88 April 2004 Table II-10. Spreadsheet Showing Numerical Manipulations of Information from Journal Papers (Continued) Corroborative Information (Continued) Solomon 1975 (Table I) [DIRS 103697], C44 Rows: A B C D E F G H I Formulas (Given) (A108*2000)*0.4 54 (Assumed) B108/C108 D108*0.75/PI() (Given) (5.48 x 1015/1.05 x 1014 ) x F108 SUM(G108:G$12 7) E108^(1/3)*2 Cumulative Number of Number of Weight (tons) Mass (kg) Density (kg/m3) Volume (m3) R3 (meter3) Number of Events (N) Per Year US Events (N) Per Year Whole Earth Events (N) Per Year Whole Earth D (meters) 1.0E-03 9.1E-01 3000 3.0E-04 7.2E-05 45.0 2.3E+03 3.4E+03 8.3E-02 1.0E-02 9.1E+00 3000 3.0E-03 7.2E-04 12.0 6.3E+02 1.1E+03 1.8E-01 1.0E-01 9.1E+01 3000 3.0E-02 7.2E-03 6.0 3.1E+02 4.3E+02 3.9E-01 1.0E+00 9.1E+02 3000 3.0E-01 7.2E-02 2.0 1.0E+02 1.1E+02 8.3E-01 1.0E+01 9.1E+03 3000 3.0E+00 7.2E-01 0.1 7.3E+00 8.7E+00 1.8E+00 1.0E+02 9.1E+04 3000 3.0E+01 7.2E+00 0.0 1.0E+00 1.4E+00 3.9E+00 1.0E+03 9.1E+05 3000 3.0E+02 7.2E+01 0.0 3.1E-01 4.0E-01 8.3E+00 1.0E+04 9.1E+06 3000 3.0E+03 7.2E+02 0.0 6.8E-02 8.3E-02 1.8E+01 1.0E+05 9.1E+07 3000 3.0E+04 7.2E+03 0.0 1.1E-02 1.5E-02 3.9E+01 1.0E+06 9.1E+08 3000 3.0E+05 7.2E+04 0.0 3.1E-03 3.9E-03 8.3E+01 1.0E+07 9.1E+09 3000 3.0E+06 7.2E+05 0.0 6.3E-04 8.0E-04 1.8E+02 1.0E+08 9.1E+10 3000 3.0E+07 7.2E+06 0.0 1.4E-04 1.7E-04 3.9E+02 1.0E+09 9.1E+11 3000 3.0E+08 7.2E+07 0.0 2.4E-05 3.8E-05 8.3E+02 1.0E+10 9.1E+12 3000 3.0E+09 7.2E+08 0.0 1.3E-05 1.4E-05 1.8E+03 1.0E+11 9.1E+13 3000 3.0E+10 7.2E+09 0.0 1.1E-06 1.4E-06 3.9E+03 1.0E+12 9.1E+14 3000 3.0E+11 7.2E+10 0.0 2.3E-07 2.8E-07 8.3E+03 1.0E+13 9.1E+15 3000 3.0E+12 7.2E+11 0.0 5.2E-08 5.2E-08 1.8E+04 (Note: * Column G uses a scalar ratio of surface of whole earth to the U.S, with values for surface areas taken from Solomon 1974 therefore internally consistent with the number of events scaled back to whole world.) Table II-10. Spreadsheet Showing Numerical Manipulations of Information from Journal Papers (Continued) ANL-WIS-MD-000019 REV 01 II-89 April 2004 Other Corroborative Information (Continued) Bailey and Emel'Yanenko 1998, C32 [DIRS 162564] (for 0.5 < d <10 km) Cumulative Diameter Distribution of Asteroids NA (>d) = 1500(Note: The value of 1500 is given in the cited paper as a constant X { d / 1 km}-2 for the stated equation) N impact = NA x Mean Probability Rows A B C D E F G H Formulas (Given) (Given) A145^-2 B145*C145 Log(D145) (Given) A145*1000 (D145*F145) Diameter (d) (km) -1500 d-2 Cumulative Number of Asteroids (NA) log NA Mean Probability of Asteroid Crossing Per Year Whole Earth Dmeteoroid (meters) Number of Impact Events (NImpact) Per Year Whole Earth 0.5 1500 4.00 6000 3.8E+00 5.0E-09 500 3.0E-05 1 1500 1.00 1500 3.2E+00 5.0E-09 1000 7.5E-06 2 1500 0.25 375 2.6E+00 5.0E-09 2000 1.9E-06 5 1500 0.04 60 1.8E+00 5.0E-09 5000 3.0E-07 7 1500 0.02 31 1.5E+00 5.0E-09 7000 1.5E-07 10 1500 0.01 15 1.2E+00 5.0E-09 10000 7.5E-08 ANL-WIS-MD-000019 REV 01 II-90 April 2004 Table II-10. Spreadsheet Showing Numerical Manipulations of Information from Journal Papers (Continued) Other Corroborative Information (Continued) * (Note: A factor of 512 is applied here in Column H to scale up to whole earth impact. The information in column B is based on a 106 km 2 area, so the number of events has to be scaled upward to the whole earth surface. The earth's surface is approximately 5.1.2 x 10 8 km2, so dividing by a factor of Bland et al. 1998 (Figure 5) [DIRS 162563], C33 106 (the area for the cited number of events in this study) leaves a scaling factor of 512 Rows A B C D E F G *H Formulas (Given) (Given) A161/1000 (Assumed) C161/D161 E161*0.75/PI() F161^(1/3)*2 Log(B161*512) after Halliday Mass (g) N (for 106 km2) Mass(kg) Density (kg/m3) Volume (m3) R3 (meter3) D (meters) Number of Events (N) Per Year Whole Earth 10 83 0.01 3000 3.3E-06 8.0E-07 1.9E-02 4.2E+04 50 15 0.05 3000 1.7E-05 4.0E-06 3.2E-02 7.7E+03 100 28 0.1 3000 3.3E-05 8.0E-06 4.0E-02 1.4E+04 500 11 0.5 3000 1.7E-04 4.0E-05 6.8E-02 5.6E+03 1000 9 1 3000 3.3E-04 8.0E-05 8.6E-02 4.6E+03 2000 5 2 3000 6.7E-04 1.6E-04 1.1E-01 2.6E+03 3000 3.5 3 3000 1.0E-03 2.4E-04 1.2E-01 1.8E+03 5000 2.1 5 3000 1.7E-03 4.0E-04 1.5E-01 1.1E+03 10000 1.2 10 3000 3.3E-03 8.0E-04 1.9E-01 6.1E+02 for Nullabor Mass (g) N (for 106 km2) Mass/kg Density (kg/m3) Volume (m3) R3 (meter3) D (meters) Number of Events (N) Per Year Whole Earth 10 35 0.01 3000 3.3E-06 8.0E-07 1.9E-02 1.8E+04 50 15 0.05 3000 1.7E-05 4.0E-06 3.2E-02 7.7E+03 100 9.2 0.1 3000 3.3E-05 8.0E-06 4.0E-02 4.7E+03 500 3.7 0.5 3000 1.7E-04 4.0E-05 6.8E-02 1.9E+03 1000 2.5 1 3000 3.3E-04 8.0E-05 8.6E-02 1.3E+03 after Zolensky (Roosevelt County) Mass (g) N (for 106 km2) Mass/kg Density (kg/m3) Volume (m3) R3 (meter3) D (meters) Number of Events (N) Per Year Whole Earth 10 930 0.01 3000 3.3E-06 8.0E-07 1.9E-02 4.8E+05 50 400 0.05 3000 1.7E-05 4.0E-06 3.2E-02 2.0E+05 100 270 0.1 3000 3.3E-05 8.0E-06 4.0E-02 1.4E+05 500 110 0.5 3000 1.7E-04 4.0E-05 6.8E-02 5.6E+04 1000 80 1 3000 3.3E-04 8.0E-05 8.6E-02 4.1E+04 ANL-WIS-MD-000019 REV 01 II-91 April 2004 Table II-10. Spreadsheet Showing Numerical Manipulations of Information from Journal Papers (Continued) Other Corroborative Information (Continued) Chapman and Morrison 1994 (Figure 1) [DIRS 135245], C36 Rows A B C D Formulas (Given) 1/A197 (Given) LOG(B197) Time Number of Events Interval (years) (N) Per Year Whole Earth D (meters) Log N 0.08 1.2E+01 3 1.1 5 2.0E-01 10 -0.7 100 1.0E-02 30 -2.0 1000 1.0E-03 100 -3.0 5.0E+04 2.0E-05 300 -4.7 7.0E+04 1.4E-05 600 -4.8 1.0E+05 1.0E-05 1000 -5.0 5.0E+05 2.0E-06 1500 -5.7 1.0E+06 1.0E-06 3000 -6.0 6.0E+06 1.7E-07 5000 -6.8 1.0E+08 1.0E-08 10000 -8.0 Chyba 1993 (p. 701) [DIRS 135248], C37 Rows: A B C D E F G H Formulas: (Given) (Given) 1/B219 (Assumed) A219/D219 E219*0.75/PI() F219^(1/3)*2 Log(C219) Mass (kg) Interval (yrs) Number of Events (N) Per Year Whole Earth Density (kg/m3) Volume (m3) R3 (meter3) D (meters) Log N 3.2E+07 21 0.05 3000 1.1E+04 2.5E+03 2.7E+01 -1.3 1.0E+06 1 1 3000 3.3E+02 8.0E+01 8.6E+00 0.0 ANL-WIS-MD-000019 REV 01 II-92 April 2004 Table II-10. Spreadsheet Showing Numerical Manipulations of Information from Journal Papers (Continued) Other Corroborative Information (Continued) Hughes 1998 [DIRS 162562], C40 after Kresak 1978 and after Shoemaker 1979 Rows: A B C D E F G H (B233*1000) (for Formulas: Kresak) F234^(1/3)*2 – (Given) (Given) (Given) (Assumed) C233/D233 F233*0.75/PI() (for Shoemaker) Source) Diameter (km) Number of Events (N) Per Year Whole Earth Mass (kg) Density (kg/m3) Volume (m3) R3 (meter3) D (meters) Kresak 1978 1 6.67E-07 – – – – 1000 Shoemaker 1979 – 3.50E-06 3.80E+11 3000 1.3E+08 3.0E+07 623 after Opik 1976 (sum of frequencies in Table 2) Rows: A B C D Formulas: (Given) (Given) B245*1000 LOG (A245) Number of Events (N) Per Year Whole Earth Diameter (km) D (meters) log N 4.6E-05 0.13 130 -4.3E+00 1.7E-06 0.52 520 -5.8E+00 7.4E-08 2.1 2100 -7.1E+00 3.8E-09 8.5 8500 -8.4E+00 2.3E-10 34 34000 -9.6E+00 5.6E-11 68 68000 -1.0E+01 4.5.3.2 Composition and Material Properties of Meteoroids Entering the Earth’s Atmosphere The following section addresses the flux in terms of percent by compositions and examines the range in possible density values. In this discussion meteors are identified as Stony, Carbonaceous, Cometary, Asteroid, Chondrite, Non-chondrite, Carbonaceous Chondrites, and Ordianry Chondrites. For this analysis comets classified as asteroidal include both Stony and Carbonaceous. Chondrite refers to a meteoric stone characterized by the presence of chondrules that are rounded granules of cosmic origin often found embedded in meteoric stones and sometimes free in marine sediments. Carbonaceous Chondrites and Ordianry Chondrites are also considered as Asterodial. The direct input justified includes: Flux data, by meteor type and related densities: The percent-by-type data is taken primarily from Item Q17 for diameters less than about 10 m, but an assumed value, based on the corroborative information, is used for the larger sizes. Corroborative information is taken from a table of independent information in Item Q17, and Items C40 and C43. The density values for two of the categories (cometary and stony) are taken from Item Q17, and the density for irons is taken from Item Q22. Corroborative information comes from separate citations with Item Q17, and other sources including Items C32, C35, C36, C37, C39, C40 and C45. Values for percent of meteor that are of iron composition: A value of five percent iron is taken from Item Q23, and corroborative information includes separate citations with Item Q23, and corroborative Items C34, C37, C39, and C43. Percent-by-Type The literature provides an intermixing of information on influx, on composition of observed fireballs, on percent composition of various meteorite finds, and on cratering rates by type of meteor. In only a few instances are distributions given based on meteoroid mass or size. The following summary tables attempt to sort and identify the percent-by-type based on information and descriptions provided in the cited sources. Because it constitutes only a few percentage of the total flux to earth, most authors do not address the percentage of iron and iron-stony material. For this analysis, however, it represents a significant potential for impact damage (due to lack of fragmentation in the atmosphere) and is addressed separately from the following discussion for cometary, carbonaceous, and stony materials. For direct input, the distribution proposed by Ceplecha (1994, Figure 2 [DIRS 135243]) (Q17) is used, along with an assumed equal distribution of asteroidal and cometary material for the large size ranges. These data are presented in Table 4 of the cited document and are provided in Table II-11. This information differs slightly from that taken Figure 2 of the same citation due to differences in mass and sizes used to choose points for the distribution. ANL-WIS-MD-000019 REV 01 II-93 April 2004 Table II-11. Distribution of Meteoroid Types (Ceplecha 1994, Table 4 [DIRS 135243]) (Q17) Diameter of Incident Body (meters) Type of Incident Body 0.1 0.2 0.5 1 2 5 10 Type I (Stony) - % 15 17 15 10 6 3 1 Type II (Carbonaceous) % 31 41 46 48 47 42 30 Type III (Cometary) - % 54 42 39 42 47 55 69 A value of five percent iron meteorites (based on Shoemaker 1983) (Q23) is used for the entire range of sizes. Corroboration of Percent of Comets, Carbonaceous, and Stony Materials With regard to the influx into the atmosphere, three corroborative sources of information present pertinent information. Hughes (1998, in Table 2, [DIRS 162562]) after Opik (1976) provides the cumulative frequency per year for asteroids and comets based on diameter of the incident body. Hughes does not clarify whether this is tied to cratering rates or represents influx to the atmosphere, but based on the nature of Opik’s work, it is presumed here to represent influx. The information from Table 2 of Hughes (1998 [DIRS 162562]) (C40) is provided in the first three rows of Table II-12. From that information, determining the percentage of cometary matter is a straightforward calculation for the given size ranges. Table II-12. Cumulative Annual Frequency of Asteroid and Comet Impacts on Earth (Hughes (1998, Table 2 [DIRS 162562]) (C40) Diameter of Incident Body (m) 130 520 2,100 8,500 34,000 68,000 Asteroid (impacts per year) 2.8 E-05 7.1 E-07 2.1 E-08 9.2 E-10 6.9 E-11 2.2 E-11 Comet (impacts per year) 1.8 E-05 9.8 E-07 5.3 E-08 2.9 E-09 1.6 E-10 3.7 E-11 Asteroid to Comet Ratio 1.58 0.72 0.39 0.32 0.43 0.57 Total Impacts (per year) 4.6E-05 1.7E-06 7.4E-08 3.8E-09 2.3E-10 5.6E-11 Percent Cometary 39.1% 57.6% 71.6% 76.3% 69.6% 66.1% The table clearly reflects that bodies of increasing diameter (regardless of type) enter the atmosphere with decreasing frequency. For FEP screening, the threshold of occurrence is set at an annual equivalence of 10-8, so incident bodies of 8,500 m or greater diameter are not of interest (on a whole-earth basis), and the percent of cometary influx of interest is in the range of 39 to 76 percent. Hughes (1998 [DIRS 162562]) (C40) also cites works of others with regard to percent of cratering based on meteor type. In most cases, the division between stony and carbonaceous asteroids is not given, so it is assumed that they are equally distributed between the two groups. In addition, for cometary material, the division between short-period and long-period comets is ignored, and the total percentage is given in Table II-13. All of the reported values from Hughes (1998 [DIRS 162562]) (C40) are reflected in statistical summary provided in Table II-13. ANL-WIS-MD-000019 REV 01 II-94 April 2004 For smaller bodies, Ceplecha (1994, Table 4 [DIRS 135243]) (Q17) provides a detailed breakdown by diameter for the size range of 0.1 to 10 m based on fireball observations and photographed meteors. The breakdown provided by Ceplecha is on fireball-types as described in Attachment IV of this document, and Ceplecha assumes that Type I represents stony materials, Type II represents carbonaceous materials, and Type III represents cometary materials. Type I materials are likely asteroidal in origin, Type II are probably transitional, and Type III are generally assumed to be cometary (Richardson and Bedient 2001, FAQ #15 [DIRS 162571]) (C43). The last column of Ceplecha’s Table 4 provides and division by type, which is from an independent data set, compared to what is shown in Table II-11 above. In FAQ #16, Richardson and Bedient (2001 [DIRS 162571]) (C43) do not provide citations for the given information on compositions, and do not provide distributions by size. However, they do indicate that most of the current information on meteoroids comes from photographic fireball studies with magnitude > -4 (whereas, the magnitudes reported by Ceplecha (1994, Table 2 [DIRS 135243]) (Q17) are general magnitude = -18. For the meteoroid population as a whole, the fainter the meteoroid population, the more likely it is cometary in origin. Richardson and Bedient (2001 [DIRS 162571]) (C43) provide the following: Cometary meteoroids: 95% Chondritic meteoroids: 5% Non-chondritic: <1% However based on the population of observed meteors with magnitude > -4, Richardson and Bedient (2001 [DIRS 162571]) (C43) provide the following: Type III - Cometary meteoroids: 38% Type IIIa – low density comets: 9% Type IIIb – high density comets: 29% Type II – Carbonaceous Chondrites: 33% Type I – Ordinary Chondrites: 29% Non-chondritic meteoroids: <1% The lack of quantification of the respective percentages and the lack of explanation of the basis for the anecdotal statements precludes their considerations in the statistical basis or listing as corroborative data. A calculation of the mean and standard deviation of the percent-by-type distribution is shown in Table II-13. The information listed in Table II-13, which falls beyond one deviation from the mean value, except as noted, has been italicized. However, these point values represent the possible range in reported values despite their apparent unreasonableness. For analysis purposes, utilizing a “preferred value” or any combination of percent compositions that honors the means and standard deviations is considered appropriate. The following information will be used for direct input. Down to an initial meteor mass of approximately 108 kg (radius of 14 m for iron, 19 m for stony, and 28 m for carbonaceous meteors), the total flux is presumed to be comprised of 5 percent iron material regardless of ANL-WIS-MD-000019 REV 01 II-95 April 2004 initial meteor radius, and the remainder is divided equally between stony and carbonaceous material regardless of initial meteor radius. For initial meteor masses below 107 and down to 101 kg (minimum radius of 0.014 m for iron, 0.019 m for stony, and 0.028 m for carbonaceous meteors), the total flux is presumed to be comprised of 5 percent iron materials regardless of initial meteor radius, and 2 to 18 percent stony material depending on initial meteor radius; and the remainder (93 to 77 percent) is attributed as carbonaceous/cometary material. These values fall within the mean value plus one standard deviation determined from the available literature, and are primarily based on Ceplecha (1994, Figure 2 and Table 4 [DIRS 135243]) (Q17) for the masses from 108 to 10-1 kg. The corroboration for an assumed 5 percent iron is presented below. Corroboration of Percent of Iron Meteoroids Because the iron and stony-iron meteorites are the least likely to be affected by atmospheric effects, and because of their increased density, the potential effects of iron meteors are considered separately by most authors from the of effects of asteroidal and cometary bodies. A listing of percentage of iron meteors in the meteoroid flux is provided below. Because of the durability of iron meteorites, both during meteor fall and through time in desert environments, meteorite falls are included in the following table as they likely represent an upper bound on the percent of iron meteors. The “falls” information differs from “find” information in that biases in collection are considered. Richardson and Bedient (2001 [DIRS 162571]) (C43) give the “find” percentage as 54 percent—clearly representing a collection and identification bias for iron and iron-stony meteorites. Information including “finds”, therefore, has been omitted. The direct input in Table II-14 is used to calculate the mean value and standard deviation for iron meteoroids. Italicized values in Table II-14 indicate that the reported values fall outside of the calculated standard deviation. However, these point values should be retained as for corroboration purposes because they represent the possible range in reported values, despite their apparent unreasonableness. For analysis purposes, utilizing a “preferred value” or any combination of percent compositions that honors the mean and standard deviations is considered appropriate. ANL-WIS-MD-000019 REV 01 II-96 April 2004 Table II-13. Summary Table for Percent by Type of Meteoroid Stony Carbonaceous Cometary Source DIRECT INPUT 16 31 53 Ceplecha (1994, Figure 2 [DIRS 135243]) (mass = 1 x 10-1 kg) 16 34 50 Ceplecha (1994, Figure 2 [DIRS 135243]) (mass = 1 kg) 18 42 40 Ceplecha (1994, Figure 2 [DIRS 135243]) (mass = 1 x 101 kg) 14 47 39 Ceplecha (1994, Figure 2 [DIRS 135243]) (mass = 1 x 10 2 kg) 10 48 42 Ceplecha (1994, Figure 2 [DIRS 135243]) (mass = 1 x 103 kg) 8 46 46 Ceplecha (1994, Figure 2 [DIRS 135243]) (mass = 1 x 104 kg) 6 42 52 Ceplecha (1994, Figure 2 [DIRS 135243]) (mass = 1 x 105 kg) 4 30 66 Ceplecha (1994, Figure 2 [DIRS 135243]) (mass = 1 x 106 kg) 2 30 68 Ceplecha (1994, Figure 2 [DIRS 135243]) (mass = 1 x 107 kg) 47 26.5 26.5 Assumed for all masses > 1 x 107 kg CORROBORATIVE INFORMATION Data Segmented as Stony, Carbonaceous and Cometary Stony Carbonaceous Cometary 14.0 29.0 57.0 Average for following values 13.1 27.2 32.9 Standard Deviation for following values 8 54 38 Ceplecha (1994, Table 4 last column, for 1 to 10 m) [DIRS 135243]) Richardson and Bedient (2001, for population as a whole 5 0 95 [DIRS 162571]) Richardson and Bedient (2001, observed meteors with magnitude >-4 29 33 38 [DIRS 162571]) ANL-WIS-MD-000019 REV 01 II-97 April 2004 Table II-13. Summary Table for Percent by Type of Meteoroid (Continued) CORROBORATIVE INFORMATION Data Segmented as Asteroidal and Cometary Asteroidal Cometary 50.7 49.3 Average for following values 22.0 22.0 Standard Deviation for following values 60.9 39.1 Hughes (1998, [DIRS 162562] after Opik 1976) 42.4 57.6 Hughes (1998, [DIRS 162562] after Opik 1976) 28.4 71.6 Hughes (1998, [DIRS 162562] after Opik 1976) 23.7 76.3 Hughes (1998, [DIRS 162562] after Opik 1976) 30.4 69.6 Hughes (1998, (DIRS 162562] after Opik 1976) 33.9 66.1 Hughes (1998, [DIRS 162562] after Opik 1976) 67 33 Hughes (1998, [DIRS 162562] after Schultz 1988) 70 30 Hughes (1998, [DIRS 162562] after Wetherhill 1989) 60 40 Hughes (1998, [DIRS 1625621] after Shoemaker et al. 1994) 90 10 Hughes (1998, [DIRS 162562] after Bailey 1991) 47.2 51.1 Average for lumped corroborative values* 23.6 23.6 Standard Deviation for lumped corroborative values* NOTE: * Italicized values indicate that the reported value falls outside of the calculated standard deviation. Asteroidal percentages should be roughly equivalent to stony plus carbonaceous percentages. Not all literature distinguishes by particular composition, so the values are shown as grouped in the source literature, and statistics are grouped accordingly. The final listed average and standard deviation assume that stony + carbonaceous percentage = asteroidal percentage, and lumps all as either asteroidal or cometary percentages. Table II-14. Summary Table for Percent of Iron Meteoroids Percent Percent Total Iron Stony Iron Percent Source DIRECT INPUT 5.0 5.0 Shoemaker (1983, p. 480 assumed value of observed objects [DIRS 135308]) CORROBORATIVE INFORMATION Average Values and Standard Deviation 4.2 1.2 4.9 Average Value for All Corroborative Information 3.5 0.9 4.0 Average Value (excluding outliers from Bevan and from Chyba) 4.3 0.9 5.0 Standard Deviation for all Corroborative Information Individual Indirect Inputs 4.8 1.1 5.9 Bevan et al. (1998, Table 4 Modern Falls [DIRS 162565]) 15.1 2.7 17.8 Bevan et al. (1998, Table 4 Australia [DIRS 162565]) 1.3 0.5 1.8 Bevan et al. (1998, Table 4 Antarctica [DIRS 162565]) 1.5 0.4 1.9 Bevan et al. (1998, Table 4 Nullarbor [DIRS 162565]) 1.9 0.7 2.5 Bevan et al. (1998, Table 4 Sahara [DIRS 162565]) 3.5 3.5 Hills and Goda (1998, p. 225 and Figure 7 [DIRS 135291]) 8 8 Chyba (1993, p. 703 – meteorite falls [DIRS 135248]) ANL-WIS-MD-000019 REV 01 II-98 April 2004 Table II-14. Summary Table for Percent of Iron Meteoroids (Continued) Percent Iron Percent Stony Iron Total Percent Source 6 6 Chyba (1993, p. 703 – main belt asteroids [DIRS 135248]) 0 0 Chyba (1993, p. 703 – lunar source for Spacewatch objects [DIRS 135248]) 6 2 8 Richardson and Bedient (2001, FAQ #15 – observed falls/fresh finds [DIRS 162571]) 1.5 1.5 Shoemaker (1983, p. 480 assumed lower value [DIRS 135308]) 3.0 3.0 Shoemaker (1983, p. 480 assumed upper value [DIRS 135308]) NOTE: * Italicized values indicate that the reported value falls outside of the calculated standard deviation for all corroborative information. Meteoroid Densities For the meteorite impact calculations, the densities used as direct input include 8 g/cm3 for metallic materials, which is consistent with Hills and Goda (1993, Figure 1 [DIRS 135281]) (Q22). This agrees with the average density for iron meteorites, and is within one standard deviation of the average value for iron plus stony irons, as shown in Table II-15. The density used as direct input for hard stone materials is 3.7 g/cm3 as taken from Ceplecha (1994, Table 1 [DIRS 135243]) (Q17) and is within one standard deviation of the average density for stony irons plus stony material plus carbonaceous material, as shown in Table II-15. The density for soft stone materials (carbonaceous and cometary materials) is 1.1 g/cm3 and is taken from Ceplecha (1992, Table 3, average bulk density [DIRS 135242]) (Q16). This agrees with the group average for carbonaceous plus cometary material shown in Table II-15. The use of these values is consistent with the use of the meteorite influx and percent-by-type information from Ceplecha (1992 [DIRS 135242]) (Q16) and 1994 [DIRS 135243]) (Q17), respectively. Corroborative information comes from Chapman and Morrison (1994, p. 34 [DIRS 135245]) (C36), who gives the possible range in densities as “the total range in bulk density is about a factor of 10 (~8 g cm-3 for iron, down to <1 g cm-3 for cometary ices).” Other corroborative peer-reviewed papers provide and/or assume differing values. Corroborating data from these sources are summarized in Table II-15, and the mean values and standard deviations are calculated. Italicized values in Table II-15 indicate that the reported value falls outside of the calculated standard deviation for both the individual type of meteor and for the groupings by meteor type. However, these point values should be retained as corroborative information because they represent the possible range in reported values, despite their apparent unreasonableness. For analysis purposes, utilizing a “preferred value” or any combination of percent compositions that honors the mean and standard deviations is considered appropriate. Table II-15 shows that the values selected for direct input satisfies that requirement. The use of these values is consistent with the use of the meteorite influx and percent-by-type information from Ceplecha (1992 [DIRS 135242]) and Ceplecha (1994 [DIRS 135243]), respectively. ANL-WIS-MD-000019 REV 01 II-99 April 2004 4.5.3.3 Crater Diameter Distributions and Rates This section justifies data being used to determine cratering distributions based on observed cratering information. The direct inputs include the following: Crater rate distribution based on observed earth cratering: This information is taken from Items Q19 and Q20, which are cross-corroborative with Item Q24. Cratering rate data for the Canadian shield and application to a hypothetical Canadian repository: This information is taken from Item Q24, which is cross-corroborative with Items Q19 and Q20. These distributions are corroborated by distributions given in Items C42, C32, C35 and C40. Grieve (1987 [DIRS 135254]) (Q19) and Wuschke et al. (1995 [DIRS 129326]) (Q24) are used as direct input for the analysis. This is because the work by Grieve is widely cited for these types of studies, and the work by Wuschke et al. has previously been applied to a potential nuclear waste repository site. One of the corroborative sources, Neukum and Ivanov (1994, Table IV [DIRS 121510]) (C42), is unique in that it estimates cratering rates for an atmosphereless earth based on lunar cratering data. They also present information on crater diameters, equivalent energy releases, and the time between events. Because it is for an atmosphereless earth, the distribution is very useful for corroboration and use as an upper bound, so it has been treated in more detailed and is corroborated to Brown et al. (2002 [DIRS 162569]) (C35) to further establish its corroborative use as an upper bound. Grieve (1987) An applicable cumulative cratering rate can be derived from Grieve (1987 [DIRS 135254]) (Q19), which is commonly used for this type of analysis. Based on observed earth crater diameters, Grieve (1987 [DIRS 135254]) (Q19) indicates that the number of impact craters larger than a crater diameter D, produced per year per square km is inversely proportional to the apparent crater diameter to the 1.8 power (Grieve 1987, p. 248p. 257 and Figure 8 [DIRS 135254]) (Q19) and further updated in , and is given as: F(D) . D-1.8 (Eq. II-9) ANL-WIS-MD-000019 REV 01 II-100 April 2004 Table II-15. Summary Table for Density of Meteors Irons plus Stony Irons 8 7.0 1.4 8 – 5 Irons (Siderites) Stony-Irons (Siderolites) 8.0 6.0 0.1 1.4 8 - 7.9 7 5 Cited Values for Density (g/cm3) Stony-Irons + Stony + Carbonaceous Carbonaceous + Cometary DIRECT INPUT 3.7 1.1 CORROBORATIVE INFORMATION 3.4 1.1 1.4 0.8 7 – 2 2.6 – 0.2 Stony (Aerolites, Ordinary Chondrites, Achondrites, Enstaties, Type I Fireballs) Carbonaceous (Carbonaceous Chondrites, Type II Fireballs) Cometary (Type III Fireballs) 3.5 2.2 0.7 0.4 0.3 0.4 2.0 0.6 3.4 2.6 2.0 0.75 0.27 1 3.5 2.2 1 3 0.5 3.65 1.3 0.2 3.7 2 4 0.8 3 0.3 Cited Sources Hills and Goda (1993, Fig 1 – assumed values [DIRS 135281]) Ceplecha (1994, Table 1 DIRS [135243]) Ceplecha (1994, Table 3 DIRS [135243]) Grouped Average Value Standard Deviation of Group Range of Values Average Value By Specific Type Standard Deviation C46b, Bailey and Emel’Yanenko 1998 (p. 14, for long period comet or Halley-type object and for near- Earth asteroid) [DIRS 162564] Brown et al. 2002, p. 294 (reported as 3,400 and 2,600 kg/m3 [DIRS 162569] Ceplecha (1994, Table 1) [DIRS 135243] (0.75 for Types IIIA, IIIAi, IIIA(C3) Ceplecha (1994, Table 1) [DIRS 135243] (0.27 for Type IIIB) Chapman and Morrison (1994, p. 34) [DIRS 135245] Chyba (1993, p. 703-704) [DIRS 135248] Hills and Goda 1993 (Figure 1 – assumed values) [DIRS 135281] Hughes 1998 (p.34 and 40: Asteroids presumed to be of stony material and cited as 3650 kg m-3) [DIRS 162562] Hughes 1998 (p. 40) [DIRS 162562] Richardson and Bedient 2001 (FAQ #16, densities reported in units of g/cc) [DIRS 162571] Richardson and Bedient 2001 (FAQ #16, densities reported in units of g/cc – upper value for given ranges) [DIRS 162571] Richardson and Bedient 2001 (FAQ #16, densities reported in units of g/cc – lower values for given ranges) [DIRS 162571] ANL-WIS-MD-000019 REV 01 II-101 April 2004 where F(D) is equal to the number of craters larger than a given diameter, produced per year per km2, as a function of diameter, D. Converting the proportionality into equation form gives: F(D) = K D-1.8 + B (Eq. II-10) Values for K and B can be derived form available observed cratering diameters. The constant B is zero since F(D) must approach zero as the crater diameter (D) becomes infinite. Grieve et al. (1995, p. 196 [DIRS 135260]) fixes F(D) for D = 20 km at (5.5 + 2.7)×10-15/km2/yr. So from Eq.10 above: F(20) = K(20)-1.8 = (5.5 + 2.7)×10-15/km2/yr, (Eq. II-10a) which allows a value of (1.2 + 0.6) ×10-12.to be assigned to K, and setting the equation for events per year per km2 in the form of F(D) = 1.2 x 10-12 x D-1.8 (Eq. II-10b) The given proportionality (D-1.8) applies for earth crater diameters greater than 10 km, per analysis by Neukum and Ivanov (1994, p. 404 [DIRS 121510]) (C42). . The deviation from the proportionality below diameters of 10 km is shown for the distribution as plotted in Figure 8 of Grieve (1987, p. 257 [DIRS 135254]) (Q19) and varies noticeably from the higher frequency of smaller diameter craters observed on lunar and other planetary surfaces (Neukum and Ivanov 1994, Figure 24 [DIRS 121510]) (C42). The slope change represents a decreased number of small crater observations and is explained by Grieve as atmospheric effects on small meteors, increased obscuration of smaller diameter craters by weathering and burial, and the implicit difficulty in identifying small diameter craters. For the purposes of the plot in Figure II-2, and calculations shown in Table II-15, the distribution was extended to the 10-m diameter, and for purposes of the analysis of probability, as discussed in later sections of this attachment, has been extended to 1-m diameter. This introduces an increased uncertainty (unquantified) in the cratering rate for small diameter (i.e., less than 10 km) craters. However, it does compensate for the obscuration of small diameter craters, and is presumed to be conservative. The basis for the presumed conservatism is that the large diameter craters, from which the proportionality is extrapolated, result from fragmentation of larger meteors, with the larger fragments less subject to atmospheric effects and dissipation than small meteors due to the initially greater mass, resulting in more and larger fragments impacting the earth surface. ANL-WIS-MD-000019 REV 01 II-102 April 2004 ANL-WIS-MD-000019 REV 01 II-103 April 2004 1 10 100 D (km) 2 D or Larger ) [DIRS 135254, DIRS 135260] ) [DIRS 135254, DIRS 135260] ) [DIRS 129326] ) [DIRS 129326] 1.0E-15 1.0E-14 1.0E-13 1.0E-12 1.0E-11 1.0E-10 1.0E-09 1.0E-08 1.0E-07 1.0E-06 0.01 0.1 Crater Diameter Number of Craters per kmper year of Diameter Grieve 1998 and 1995 (corroborated for D > 10 kmGrieve 1988 and 1995 (extrapolated for D < 10 kmWuschke et al. 1995 (corroborated for D > 0.5 kmWuschke et al. 1995 (extrapolated for D < 0.5kmNeukum and Ivanov 1994 (for atmosphereless earth) [DIRS 121510] Figure II-2. Cratering Rate Distribution Table II-16a. Cratering Rate Distribution for Direct Input Grieve 1987 [DIRS 135254], Q19 and Grieve et al. 1995 [DIRS 135260], Q20 Wuschke et al. 1995, Equation 3 [DIRS 129326], C32 Crater Diameter (km) Annual Frequency / km2 Crater Diameter (km) Annual Frequency / km2 0.01 4.8E-09 0.01 2.0E-08 0.1 7.6E-11 0.1 2.0E-10 1 1.2E-12 1 2.0E-12 5 6.6E-14 5 8.0E-14 10 1.9E-14 10 2.0E-14 20 5.5E-15 20 5.0E-15 Table II-16b. Cratering Rate Distributions Used for Corroborative-Use-Only Hughes (1998 [DIRS 162562], C40) Neukum and Ivanov (1994, Table IV [DIRS 121510], C42) Crater Diameter (km) Annual Frequency / km2 Crater Diameter (km) Annual Frequency / km2 0.01 2.2E-08 0.01 7.1E-07 0.1 2.2E-10 0.1 8.1E-09 1 2.1E-12 1 1.2E-12 5 8.4E-14 5 1.8E-14 10 2.1E-14 10 7.6E-15 20 5.2E-15 20 3.7E-15 C46b, Bailey and Emel’Yanenko 1998 [DIRS 162564] (Assuming all cometary) (Assuming all asteroid) (Observed cratering) Diameter (km) Annual Frequency / km2 Diameter (km) Annual Frequency / km2 Diameter (km) Annual Frequency / km2 0.1 1.4E-10 0.1 4.8E-10 0.1 2.4E-10 1 2.1E-12 1 3.1E-12 1 2.4E-12 5 1.1E-13 5 9.4E-14 5 9.4E-14 10 3.0E-14 10 2.1E-14 10 2.4E-14 20 8.4E-15 20 4.6E-15 20 5.9E-15 ANL-WIS-MD-000019 REV 01 II-104 April 2004 Wuschke et al. (1995) For Wuschke et al. (1995, p. 44 [DIRS 129326]) (Q24), the distribution is derived from subsets of the observed Earth cratering distribution used by Grieve (1987 [DIRS 135254]) (Q19). The equation is given as: -1 . = 2.0×10-12×D-2×A a(Eq. II-11) where . is the frequency of cratering events of diameter D (km) or larger represented on an annual basis (a) that occur in target area A (km2). Putting . = F(D) and setting A = 1 km2 sets this equation in a form similar to that for Grieve. F(D) = 2.0×10-12(D)-2 (Eq. II-11a) This denotes a slightly steeper slope compared to Grieve (2.0×10-12 compared to Grieves 1.2 + 0.6 ×10-12). Wuschke’s approach slightly decreases the annual frequency for a 20-km diameter crater (5.0 x 10-15 per km2 compared to the values from Grieve of 5.5 x10-15 km2). This difference is reflected in the plot in Figure II-2. Neukum and Ivanov (1994) This distribution was previously discussed in this attachment, and the meteor diameter distribution was shown to be adequate and appropriate for use as corroborative information for meteoroid flux. Neukum and Ivanov (1994 [DIRS 121510]) (C42) is based on the lunar cratering rate, with the lunar crater diameter distribution adjusted for earth conditions by assuming an “atmosphereless” earth (i.e., not adjusted for ablation or atmospheric effects, but effects of gravity on crater diameters are considered). The corroborative information from Neukum and Ivanov (1994 [DIRS 121510]) (C42) is given in Table II-17. Table II-17. Cratering Rate Distribution for “Atmosphereless” Earth Neukum and Ivanov (1994, Table IV [DIRS 121510], C42) Crater Diameter (km) Energy Release (MT) Time Interval (year) for Whole Earth 0.01 2.65E-07 2.75E-03 0.1 5.26E-04 2.42E-01 1.0 2.58E+00 1.60E+03 5 4.21E+02 1.10E+05 10 4.43E+03 2.58E+05 20 4.66E+04 5.25E+05 To show adequacy and appropriateness, the corroborative work of Brown et al. (2002 [DIRS 162569]) is used for comparison. The work by Brown et al. (2002 [DIRS 162569]) (C35) is based on direct observation of bolide events (a bolide is a meteor that show signs of explosion or fragmentation), and the study uses observed energy releases in Earth’s atmosphere to determine flux. The work is described in more detail in this attachment and was previously evaluated based on meteor diameter equivalents. By showing corroboration between the energy releases directly observed by Brown et al. (2002 [DIRS 162569]) (C35) and the theoretical equivalents determined by Neukum and Ivanov (1994 [DIRS 121510]) (C42), the equivalent cratering rate provided in the Neukum and Ivanov (1994 [DIRS 121510]) (C42) can be ANL-WIS-MD-000019 REV 01 II-105 April 2004 evaluated. In effect, this has already been achieved in that the Neukum and Ivanov (1994 [DIRS 121510]) (C42) relates the meteor diameter to crater diameters, and Brown et al. (2002 [DIRS 162569]) (C35) and Neukum and Ivanov (1994 [DIRS 121510]) (C42) were both shown to be adequate and appropriate for use as direct input for meteoroid flux. Regardless, the comparison of Brown et al. (2002, Figure 4 [DIRS 162569]) (C35) to Neukum and Ivanov (1994, Table IV [DIRS 121510]) (C42) is shown on Figure II-3, with the Neukum and Ivanov (1994 [DIRS 121510]) (C42) information converted from megaton (mt) to kiloton (kt) by multiplying by a factor of 103. The cratering rate distribution based on Neukum and Ivanov (1994, Table IV [DIRS 121510]) (C42) represents and upper bound to the cratering rate distribution for smaller diameter craters, and is shown on Figure II-2 for comparison to other cratering rate distributions that are used as technical and corroborative information for the analysis. 1 E+01 1 E+03 1 E+05 1 E+01 1 E+03 1 E+05 1 E+07 Number of Events per Year (Whole Earth) 1 E-07 1 E-05 1 E-03 1 E-01 1 E-05 1 E-03 1 E-01 Energy Release (kt TNT equivalent) Brown et al. 2002 [162569] Neukum and Ivanov 1994 (Table IV) [121510] Figure II-3. Frequency of Meteor Energy Release in Earth’s Atmosphere Given the previous comparison in this attachment and that on Figure II-3, the plot of Neukum and Ivanov (1994 Table IV [DIRS 121510]) (C42) falls within about one-half order of magnitude of the plot for Brown et al. (2002 [DIRS 162569]) (C35), the corroborative information in Table II-17 is appropriate for its intended use. The use of this information, however, must ANL-WIS-MD-000019 REV 01 II-106 April 2004 recognize that it is for an “atmosphereless” earth and any calculations or use must be adjusted accordingly. Additional Corroborative Information The additional distribution equations represented on Figure II-2 and in Table II-16 includes distributions provided by equations in C46b, Bailey and Emel’Yanenko (1998, Equations 4 and 10, and p. 15 [DIRS 162564]) and by Hughes (1998, Equation 2, p. 4 [DIRS 162562]) (C40). The equations from C46b, Bailey and Emel’Yanenko (1998 [DIRS 162564]) for assumed cometary and asteroidal flux are based on kinetic energy of the meteor, material properties of the impacted surface, and associated scaling laws. C46b, Bailey and Emel’Yanenko (1998 [DIRS 162564]) is focused on large-scale diameter craters, and likely applies to crater diameters of 20 km or greater, although this is not specifically stated. The equation, assuming all impacts are cometary, is given (Bailey and Emel’Yanenko (C32) Eq. 10 [DIRS 162564]) in the form of: -1.84-1 Nc (>D) ˜ 4.3×10-6 (D/20km) a(Eq. II-12) where: Nc is the number of cometary-cratering events of Diameter D or larger that occur per year and assumes that all influx is cometary in nature. Putting Nc (>D) = F(D), stating it on an annual basis, and dividing by the area of the earth’s surface (5.1 x 108 km2) sets this equation in a form similar to that for Grieve for annual frequency per km2. -1.84 F(D) = 2.1×10-12 (D) (Eq. II-12a) The equation assuming all impacts are asteroidal is given Bailey and Emel’Yanenko (C32, Eq. 4 [DIRS 162564]) in the form of: –2.18-1 Nc (>D) ˜ 2.34×10-6 (D/20km) a(Eq. II-13) where: Nc is the number of asteroidal-cratering events of Diameter D or larger that occur per year and assumes that all influx is asteroidal in nature. Putting Nc (>D) = F(D), stating it on an annual basis, and dividing by the area of the earth’s surface (5.1 x 108 km2) sets this equation in a form similar to that for Grieve for annual frequency per km2. –2.18 F(D) = 3.2×10-12 (D) (Eq. II-13a) The observed cratering rate is given (p. 15 [DIRS 162564]) as -2-1 N = 3×10-6 D20 a(Eq. II-14) where: N is the number of cratering events of Diameter D or larger that occur per year for the whole earth. Putting N= F(D), stating D20 as (D/20 km), restating it on an annual basis, and dividing by the area of the earth’s surface (5.1 x 108 km2) sets this equation in a form similar to that for Grieve for annual frequency per km2. –2.18 F(D) = 2.4 ×10-12 (D) (Eq. II-14a) ANL-WIS-MD-000019 REV 01 II-107 April 2004 Hughes (1998, Equation 2 [DIRS 162562]) (C40) is stated as strictly applying only to the range of diameters of 19 10 km) [DIRS 135254, DIRS 135260] Grieve 1987 and 1995 (extrapolated for D < 10 km) (DIRS 135254, DIRS 135260] Wuschke et al. 1995 (corroborated for D > 0.5 km) [DIRS 129326] Wuschke et al. 1995 (extrapolated for D < 0.5km) [DIRS 129326] Neukum and Ivanov 1994 (for atmosphereless earth) (DIRS 121510] Figure IV-1. Cratering Rate Distribution from Three Sources 2.2.1 Grieve (1987) An applicable cumulative cratering rate (and one commonly used for these types of analyses) can be derived from Grieve (1987 [DIRS 135254]), Grieve et al. (1995 [DIRS 135260]), and Grieve (1998 [DIRS 163385]). The number of impact craters larger than a crater diameter D, produced per year per square km is proportional to the apparent crater diameter to the –1.8 power (Grieve 1987, p. 257 and Figure 8 [DIRS 135254]). Using the Fundamental Theorem of Calculus, and the definition of F(D) provided in Equation 9 of Attachment II of this analysis report, a distribution function for the frequency of impact for craters of a given diameter D can be found. By definition: 8 F(D) = .f(x)dx = K D-1.8 (Eq. IV-1) 0 Therefore: f(D) = 1.8 K D-2.8. (Eq. IV-2) ANL-WIS-MD-000019 REV 01 IV-5 April 2004 Equations IV-1 and IV-2 will be used later in this attachment to determine the frequency of impact cratering in the repository area. As shown in Section 4.5.3.3 of this Attachment II (Equation IV-10b), the value of K is fixed at 1.2×10-12, based on the frequency of earth craters with diameter of 20 km or greater. That equation is restated here as: F(D) = 1.2 x 10-12 x D-1.8 (Eq. IV-3) where F(D) is equal to the number of craters larger than a given diameter, produced per year per km2, as a function of diameter, D. A plot for this equation is provided in Figure IV-1. Using a repository emplacement area of no greater than 11.9 km2 (see Section 2.3.1) then the cratering diameter of interest is that associated with an annualized probability of 8.4×10-10/km2 (i.e., 8.4 x 10-10/km2 multiplied by an area of 11.9 km2 roughly equates to an annualized probability of 1 x10-8, which is the regulatory threshold for consideration). Based on Figure IV-3, this equates to a crater diameter of no more than 30 m. It should be noted that the Grieve distribution is routinely cited as being applicable only for crater diameters of greater than 20 km, although Neukum and Ivanov (1994 [DIRS 121510]) support use of the distribution down to diameters of as low as 10 km. Given the distribution of crater diameters by Grieve (1998 [DIRS 163385]), it is conservative (in relation to observed craters) to extend the distribution to lesser diameters. This is because the extrapolation overstates the number of craters that would occur compared to the actual number observed to date. However, the number of observed small diameter craters is obscured by the ability to recognize such features and the destruction through time due to natural and anthropogenic processes, so the degree of true conservatism cannot be quantified. Using the exhumation and fracturing depth relationships described in Section 2.3.2, a crater diameter of 30 m could result in an exhumation depth on the order of 3 to 10 m, which is insufficient to exhume waste at the depth of the proposed repository (i.e., greater than 200 m below ground surface (BSC 2003, Section 7.1.8 [DIRS 165572]). With regard to fracturing, the depth of fracturing could be as little as 10 m to as great as 23 m. These depths are insufficient to reach the repository depth or to significantly alter infiltration through the Paintbrush nonwelded unit. 2.2.2 Wuschke et al. (1995) A particular example of the use of Grieve distribution and the consideration of exhumation and fracturing depths is presented in Wuschke et al. (1995 [DIRS 129326]). The analyses presented therein was for a hypothetical depository deep in plutonic rock of the Canadian shield, located at least 500 m below ground surface with a total area of 4 km2. The curve from Wuschke et al., if comparable to the information used by Hughes (1998, p. 34 [DIRS 162562]), may only be valid down to diameters of 1 km. For Wuschke et al. (1995, p. 44 [DIRS 129326]), the distribution is derived from subsets of the observed earth cratering distribution used by Grieve (1987 [DIRS 135254]). The equation (Equation II-11a in Attachment II of this document) is given as: F(D) = 2.0×10-12(D)-2 (Eq. IV-4) This denotes a slightly steeper slope compared to Grieve (2.0×10-12 compared to Grieves 1.2 + 0.6 ×10-12). Wuschke’s approach slightly decreases the annual frequency for a 20-km diameter ANL-WIS-MD-000019 REV 01 IV-6 April 2004 crater (5.0 x 10-15 per km2 compared to the values from Grieve of 5.5 x10-15 km2). This difference is reflected in the plot in Figure IV-1. The findings of this study are presented in Table 1 of Wuschke et al. (1995, p. 26 [DIRS 129326]) and provide the annual probability and cumulative probability for 10,000 years for meteorite impact events. The results indicate that the annualized probability of impact for the Canadian repository design sufficient to cause damage by exhumation and fracturing is approximately 7.6 x 10-12 to 6.5 x 10-11 per year, respectively. This is associated with crater diameters of 7.6 to 0.66 km for exhumation and fracturing, respectively. Given the parameters used for the hypothetical Canadian repository (area of 4 km2 and depth of 500 m), the reported probabilities should be less than the probability of impact for the Yucca Mountain repository (depths greater than 200 m below the surface and total area not to exceed 11.9 km2 [BSC 2003, Section 7.1.8 and Figure 1, respectively [DIRS 165572]) for the same effects of exhumation and fracturing. For exhumation of the Yucca Mountain repository, the least frequent and maximum crater diameter that could cause such an event is a crater diameter of 2 km (i.e., 200 m/0.10) and the most frequent would be a crater diameter of 625 m (200 m/0.32). Based on Figure IV-3, and using a siting area of 11.9 km2, such events occur with annual frequencies on the order of 6 x 1012 to 6 x 10-11, or about an order of magnitude more frequently than for the hypothetical Canadian design. For fracturing to repository depth, the crater diameter of interest is 263 m (i.e., 200 m/0.76). This occurs, based on Figure IV-3, with an annual frequency of 3.6 x10-10, and again this is more frequent than predicted for the Canadian repository as expected. Using the probability threshold before for the Yucca Mountain repository, the crater diameter associated with a 8.4×10-10 probability (i.e., 8.4 x 10-10 / yr-km2 x 11.9 km2 = 1 x 10-8 / yr) for the distribution from Wuschke et al. (1995 [DIRS 129326]) is no more than 60 m, and slightly greater than that from for Grieve distribution, as shown in Figure IV-3. This results in a maximum exhumation depth of about 20 m and a maximum fracturing depth of about 46 m. These depths are insufficient to reach to the proposed Yucca Mountain repository depth or to significantly alter infiltration through the Paintbrush nonwelded unit. 2.2.3 Neukum and Ivanov (1994) The plot of the Neukum and Ivanov (1994 [DIRS 121510]) information represents a true upper bound (i.e., an “atmosphereless” earth which neglects effects of ablation and fragmentation). Because it is unrealistic due to an “atmosphereless” earth, it is discussed for corroborative purposes only, but it also provides a true upper bound. Neukum and Ivanov (1994, Table IV [DIRS 121510]) provides a tabulation of impact accumulation rates and mean time intervals between impacts for earth, based on lunar craters and adjusted for gravity differences. This table includes the mean interval between events with energies equal to or greater than that required to form a crater of a given diameter. The cumulative cratering rate (or frequency) of such events can be derived from the calculated mean intervals by using the inverse of the mean interval. The frequency per-square-km of the earth’s surface can be derived by dividing the frequency by the area of earth’s surface. This curve represents an extreme upper bound for the cratering rate on earth in the range of crater diameters of interest as it accounts for gravity differences between the lunar and earth surfaces and includes data for small-diameter craters. It does not take into account atmospheric shielding effects, ANL-WIS-MD-000019 REV 01 IV-7 April 2004 which are known to exist and are significant in reducing crater frequency and size. The data used in plotting Figure IV-1 is found in Section 4.5, Table II-17 of Attachment II. Given that the footprint area is no greater than 11.9 km2 as previously mentioned, then the cratering diameter of interest is that associated with an annualized probability of 8.4×10-10/km2 (i.e., 8.4 x 10-10/km2 multiplied by an area of 11.9 km2 roughly equates to an annualized probability of 1×10-8, which is the regulatory threshold for consideration). Based on Figure IV-1, this equates to a crater diameter of slightly less than 200 m. Using the exhumation depth relationship mentioned above such a crater diameter could result in exhumation depths greater than 20 m and less than 64 m, which are insufficient to exhume waste at the depth of the proposed repository (i.e., greater than 200 m below ground surface (BSC 2003, Section 7.1.8 [DIRS 165572]) or to exhume significant portions of the Paintbrush hydrogeologic unit. With regard to fracturing, the depth could be as little as 70 m to as great as 150 m. These depths are insufficient to reach to the proposed repository depth, although the values may represent depths that are sufficient to fracture to the Paintbrush nonwelded unit in the eastern portions of the siting area. Depending on the choice of factors (0.3 or 0.76) the fracturing may or may not be penetrate throughout the Paintbrush nonwelded unit in the emplacement area. However, it must be kept in mind that the stated values represent the “worst-case” model proposed in the literature for exhumation and fracturing, coupled with the “upper bound” for crater diameter distribution. They are not realistic in that they are based on an “atmosphereless” earth. 2.2.4 Probability of Impact Based on Meteoroid Influx and Meteoroid Characteristics The direct application of the Neukum and Ivanov cratering distribution is limited because it does not consider atmospheric shielding. The Grieve distribution and the Wushcke distribution are limited because they are applicable for large-diameter craters, but uncertain for small diameter craters. Consequently, to determine probabilities of meteorite-impact cratering damage, a cratering diameter distribution curve is developed based on cumulative meteoroid influx information developed during the 1980s and 1990s. The flux distribution is applied against information on percent by type and density of meteors to determine a flux by meteor size and type. The resulting meteor diameters are then coupled with direct input relating initial meteor radius to resulting crater size, and an effective cratering distribution is determined that accounts for atmospheric shield effects such as ablation and fragmentation. 2.2.4.1 Mass Flux of Meteoroids Ceplecha (1992 [DIRS 135242]) has compiled flux information from a variety of authors for masses ranging from 10-21 to 10 15 kg (46 orders of magnitude). This compilation is provided in graphical form (Ceplecha 1992, Figure 1 [DIRS 135242]) as the log of the mass (m) to the log of the cumulative number (N) of interplanetary bodies of a mass equal to or greater than m coming to the earth’s atmosphere every year. The present analysis of probability, however, is only concerned with the range of bodies capable of creating craters in the earth’s surface. Selected values from the cited figure over the potential range of interest are provided in Table IV-1, which describes the flux of material coming to the entire earth’s atmosphere. This information is provided on Figure II-1 of Attachment II of this analysis report. This direct input is justified for use in Section 4.5.3.2 and Table II-10 of Attachment II. ANL-WIS-MD-000019 REV 01 IV-8 April 2004 Table IV-1. Mass Flux used as Direct Input Ceplecha 1992, Figure 1 [DIRS 135242] Log Mass (kg) Mass (kg) Number of Events Per Year Whole Earth -1 1.0E-01 3.2E+05 0 1.0E+00 1.0E+05 1 1.0E+01 1.6E+04 2 1.0E+02 1.0E+04 3 1.0E+03 1.6E+03 4 1.0E+04 6.3E+02 5 1.0E+05 1.0E+02 6 1.0E+06 1.0E+01 7 1.0E+07 1.0E-01 8 1.0E+08 1.0E-02 9 1.0E+09 1.0E-03 10 1.0E+10 1.0E-04 11 1.0E+11 1.0E-05 12 1.0E+12 3.2E-06 13 1.0E+13 1.0E-06 14 1.0E+14 1.0E-07 15 1.0E+15 3.2E-08 The mass distribution from Ceplecha (1992, p. 362 and Figure 1 [DIRS 135242]) was chosen for use in this analysis because it provides a conservative estimate compared to influx determined from lunar cratering data or from direct observation of energy releases in earth’s atmosphere by geostationary satellites. The degree of conservatism is approximately one-half to one order of magnitude in terms of the number of events occurring for a meteor of a given diameter. For consistency and traceability, the use of a single distribution was preferred to construction of a fully conservative data set constructed by hand-picking the maximum values from the literature for any given meteor diameter. This distribution does not however, address the nature of the material, its velocity, atmospheric shielding effects, the frequency and size of material actually impacting the earth’s surface, or the resulting impact crater size. 2.2.4.2 Influx of Meteoroids Based on Percent by Type As defined by Chapman and Morrison (1994, p. 34 [DIRS 135245]) and by Shoemaker (1983, p. 464 [DIRS 135308]), meteor composition is described as metallic (iron to iron-nickel, and relatively rare), stony (mixtures of iron and stony material, chondritic–type S asteroids), or cometary (low-density silicates, organics and volatiles–type C asteroids). The term carbonaceous is also used for those bodies that lie between stony and cometary bodies. The differences in composition also reflect differences in the structural make-up and strength of the meteors. Down to an initial meteor mass of approximately 108 kg (radius of 14 m for iron, 19 m for stony, and 28 m for carbonaceous meteors), the total flux is comprised of 5 percent iron material ANL-WIS-MD-000019 REV 01 IV-9 April 2004 regardless of initial meteor radius, and the remainder is divided equally between stony and carbonaceous material regardless of initial meteor radius. For initial meteor masses below 108 and down to 10-1 kg (minimum radius of 0.014 m for iron, 0.019 m for stony, and 0.028 m for carbonaceous meteors), the total flux is comprised of 5 percent iron materials, regardless of initial meteor radius; 2 to 18 percent stony material depending on initial meteor radius; and the remainder (93 to 77 percent) is attributed as carbonaceous/cometary material. The bases for these values, and the qualification of this data, are discussed in Section 4.5.3.2 and Tables II-13 and II-14 of Attachment II. The values are applied to the mass influx to derive at a number of events by type. The result distribution considering percent-by-type is provided in Table IV-2. 2.2.4.3 Density and Initial Radii of Meteoroids For the meteorite impact calculations, the densities used for meteoroids are 8 g/cm3 for metallic materials, 3.7 g/cm3 for stony materials, and 1.1 g/cm3 for carbonaceous /cometary materials. The bases for these values are discussed, and the data justified for use, in Section 4.5.3.2 and Table II-15 of Attachment II. The use of these values is consistent with the use of the meteorite influx and percent-by-type information from Ceplecha (1992 [DIRS 135242]) and Ceplecha (1994 [DIRS 135243]), respectively. The total range in bulk densities can vary from 8 g/cm3 to less than 1 g/cm3 for the metallic and cometary materials respectively (Chapman and Morrison 1994, p. 34 [DIRS 135245]). The basis for these density values used in the analysis is discussed in Section 4.5.3.2 and Table II-15 of Attachment II. For the meteorite impact calculations, the densities used for meteoroids are 8 g/cm3 for metallic materials, 3.7 g/cm3 for stony materials, and 1.1 g/cm3 for soft stone/carbonaceous /cometary materials. By using the flux values from Ceplecha (1992 [DIRS 135242]), described above and presented in Table IV-2, and assuming spherical meteoroids with the density values listed above, the corresponding radius by meteoroid composition can be calculated. As used to determine the radius listed in Table IV-3, the mass (m) of a sphere is: m= (4/3 p R3 )(.) (Eq. IV-5) where: m = mass (kg) .= density (kg/m3), which is 103 times g/cm3 R = radius (m) and correspondingly: R = [(m / (4/3 p.)]1/3 (Eq. IV-5a) ANL-WIS-MD-000019 REV 01 IV-10 April 2004 ANL-WIS-MD-000019 REV 01 IV-11 April 2004 Table IV-2. Annualized Mass Influx and Percent by Type Allocation Log Ntotal, Annualized Nstone Annualized Ncomet, Annualized Number of Ntotal Annualized Niron Annualized Number of Hard Percent Soft Number of Soft Log m (kg) Mass (kg) Events (N), whole earth Number of Events per km2 Percent Iron Number of Iron Events per km2 Percent Hard Stone Stone Events per km2 Stones and Comets Stone and Comet Events per km2 -1 1.0E-01 5.5 6.2E-04 0.05 3.1E-05 0.16 9.9E-05 0.79 4.9E-04 0 1.0E+00 5 2.0E-04 0.05 9.8E-06 0.16 3.1E-05 0.79 1.5E-04 1 1.0E+01 4.2 3.1E-05 0.05 1.6E-06 0.18 5.6E-06 0.77 2.4E-05 2 1.0E+02 4 2.0E-05 0.05 9.8E-07 0.14 2.7E-06 0.81 1.6E-05 3 1.0E+03 3.2 3.1E-06 0.05 1.6E-07 0.10 3.1E-07 0.85 2.6E-06 4 1.0E+04 2.8 1.2E-06 0.05 6.2E-08 0.08 9.9E-08 0.87 1.1E-06 5 1.0E+05 2 2.0E-07 0.05 9.8E-09 0.06 1.2E-08 0.89 1.7E-07 6 1.0E+06 1 2.0E-08 0.05 9.8E-10 0.04 7.8E-10 0.91 1.8E-08 7 1.0E+07 -1 2.0E-10 0.05 9.8E-12 0.02 3.9E-12 0.93 1.8E-10 8 1.0E+08 -2 2.0E-11 0.05 9.8E-13 0.47 9.2E-12 0.48 9.4E-12 9 1.0E+09 -3 2.0E-12 0.05 9.8E-14 0.47 9.2E-13 0.48 9.4E-13 10 1.0E+10 -4 2.0E-13 0.05 9.8E-15 0.47 9.2E-14 0.48 9.4E-14 11 1.0E+11 -5 2.0E-14 0.05 9.8E-16 0.47 9.2E-15 0.48 9.4E-15 12 1.0E+12 -5.5 6.2E-15 0.05 3.1E-16 0.47 2.9E-15 0.48 3.0E-15 13 1.0E+13 -6 2.0E-15 0.05 9.8E-17 0.47 9.2E-16 0.48 9.4E-16 14 1.0E+14 -7 2.0E-16 0.05 9.8E-18 0.47 9.2E-17 0.48 9.4E-17 15 1.0E+15 -7.5 6.2E-17 0.05 3.1E-18 0.47 2.9E-17 0.48 3.0E-17 NOTES: 1 Based on Ceplecha (1992 [DIRS 135242] and 1994 [DIRS 135243]) 2Mass and associated number of events based of the direct input from Ceplecha 1992 [DIRS 135242] as discussed in Section 4.5.3.1 and Table II-10 of Attachment II of this analysis report. Percent by type based on direct inputs given in Table II-13 and II-14 of Attachment II of this analysis report. Table IV-3 is primarily interested in accounting for differences in size and type, due to later use in the analysis for determining resulting crater diameters, so differing densities are used. By using the flux values from Ceplecha (1992 [DIRS 135242]), described above and presented in Table IV-2, and assuming spherical meteoroids with the density values listed above, the corresponding radius by meteoroid composition is calculated. Table IV-3. Annualized Number of Events by Meteor Type and Radius Iron Meteors Annualized Number of Events Niron Initial Meteor per km2 Mass m (kg) Density (kg/m3) Volume (m3) R3 Radius (m) 3.1E-05 1.00E-01 8000 1.3E-05 3.0E-06 1.4E-02 9.8E-06 1.00E+00 8000 1.3E-04 3.0E-05 3.1E-02 1.6E-06 1.00E+01 8000 1.3E-03 3.0E-04 6.7E-02 9.8E-07 1.00E+02 8000 1.3E-02 3.0E-03 1.4E-01 1.6E-07 1.00E+03 8000 1.3E-01 3.0E-02 3.1E-01 6.2E-08 1.00E+04 8000 1.3E+00 3.0E-01 6.7E-01 9.8E-09 1.00E+05 8000 1.3E+01 3.0E+00 1.4E+00 9.8E-10 1.00E+06 8000 1.3E+02 3.0E+01 3.1E+00 9.8E-12 1.00E+07 8000 1.3E+03 3.0E+02 6.7E+00 9.8E-13 1.00E+08 8000 1.3E+04 3.0E+03 1.4E+01 9.8E-14 1.00E+09 8000 1.3E+05 3.0E+04 3.1E+01 9.8E-15 1.00E+10 8000 1.3E+06 3.0E+05 6.7E+01 9.8E-16 1.00E+11 8000 1.3E+07 3.0E+06 1.4E+02 3.1E-16 1.00E+12 8000 1.3E+08 3.0E+07 3.1E+02 9.8E-17 1.00E+13 8000 1.3E+09 3.0E+08 6.7E+02 9.8E-18 1.00E+14 8000 1.3E+10 3.0E+09 1.4E+03 3.1E-18 1.00E+15 8000 1.3E+11 3.0E+10 3.1E+03 Hard Stone Meteors Annualized Number of Events Nstone Initial Meteor per km2 Mass m (kg) Density (kg/m3) Volume (m3) R3 Radius (m) 9.9E-05 1.00E-01 3700 2.7E-05 6.5E-06 1.9E-02 3.1E-05 1.00E+00 3700 2.7E-04 6.5E-05 4.0E-02 5.6E-06 1.00E+01 3700 2.7E-03 6.5E-04 8.6E-02 2.7E-06 1.00E+02 3700 2.7E-02 6.5E-03 1.9E-01 3.1E-07 1.00E+03 3700 2.7E-01 6.5E-02 4.0E-01 9.9E-08 1.00E+04 3700 2.7E+00 6.5E-01 8.6E-01 1.2E-08 1.00E+05 3700 2.7E+01 6.5E+00 1.9E+00 7.8E-10 1.00E+06 3700 2.7E+02 6.5E+01 4.0E+00 3.9E-12 1.00E+07 3700 2.7E+03 6.5E+02 8.6E+00 9.2E-12 1.00E+08 3700 2.7E+04 6.5E+03 1.9E+01 9.2E-13 1.00E+09 3700 2.7E+05 6.5E+04 4.0E+01 9.2E-14 1.00E+10 3700 2.7E+06 6.5E+05 8.6E+01 ANL-WIS-MD-000019 REV 01 IV-12 April 2004 Table IV-3. Annualized Number of Events by Meteor Type and Radius (Continued) Annualized Number of Events Nstone Initial Meteor per km2 Mass m (kg) Density (kg/m3) Volume (m3) R3 Radius (m) 9.2E-15 1.00E+ 1 3700 2.7E+07 6.5E+06 1.9E+02 2.9E-15 1.00E+1 3700 2.7E+08 6.5E+07 4.0E+02 9.2E-16 1.00E+1 3700 2.7E+09 6.5E+08 8.6E+02 9.2E-17 1.00E+1 3700 2.7E+10 6.5E+09 1.9E+03 2.9E-17 1.00E+1 3700 2.7E+11 6.5E+10 4.0E+03 Soft Stone Meteors Annualized Number of Events Ncomet Initial Meteor per km2 Mass m (kg) Density (kg/m3) Volume (m3) R3 Radius (m) 4.9E-04 1.00E-01 1100 9.1E-05 2.2E-05 2.8E-02 1.5E-04 1.00E+00 1100 9.1E-04 2.2E-04 6.0E-02 2.4E-05 1.00E+01 1100 9.1E-03 2.2E-03 1.3E-01 1.6E-05 1.00E+02 1100 9.1E-02 2.2E-02 2.8E-01 2.6E-06 1.00E+03 1100 9.1E-01 2.2E-01 6.0E-01 1.1E-06 1.00E+04 1100 9.1E+00 2.2E+00 1.3E+00 1.7E-07 1.00E+05 1100 9.1E+01 2.2E+01 2.8E+00 1.8E-08 1.00E+06 1100 9.1E+02 2.2E+02 6.0E+00 1.8E-10 1.00E+07 1100 9.1E+03 2.2E+03 1.3E+01 9.4E-12 1.00E+08 1100 9.1E+04 2.2E+04 2.8E+01 9.4E-13 1.00E+09 1100 9.1E+05 2.2E+05 6.0E+01 9.4E-14 1.00E+10 1100 9.1E+06 2.2E+06 1.3E+02 9.4E-15 1.00E+11 1100 9.1E+07 2.2E+07 2.8E+02 3.0E-15 1.00E+12 1100 9.1E+08 2.2E+08 6.0E+02 9.4E-16 1.00E+13 1100 9.1E+09 2.2E+09 1.3E+03 9.4E-17 1.00E+14 1100 9.1E+10 2.2E+10 2.8E+03 3.0E-17 1.00E+15 1100 9.1E+11 2.2E+11 6.0E+03 NOTES: Number of events and mass taken from Table IV-2 of this attachment. Densities taken from direct input in Table II-15 of Attachment II of this analysis report and converted from g/cm3 to kg/m3. 2.2.4.4 Atmospheric Shielding Effects Upon entering the earth’s atmosphere, a meteor is subject to multiple destructive processes including ablation and fragmentation caused by heating and differential stresses. These processes tend to dissipate energy into the atmosphere. The magnitude of the atmospheric dissipation of energy is a function of the radius and composition of the body, the initial entry velocity, and the angle of the entry. Hills and Goda (1998, p. 228 [DIRS 135291]) provide a series of figures that show the fraction of energy dissipated into the atmosphere for various radii of meteors. The dissipation of energy is such a significant effect that, for a certain range of radii and initial velocities, the energy dissipation is total and no surface impact occurs. ANL-WIS-MD-000019 REV 01 IV-13 April 2004 The relationship used in this analysis between initial meteoroid diameter and crater diameter is extracted from Hills and Goda (1993, Figures 16 and 17 [DIRS 135281]). These figures represent the results of modeling that is documented in the peer-reviewed paper, and include atmospheric effects such as fragmentation of the meteors, changing velocity of dispersed fragments, radius of the debris cloud, and energy dissipation in the atmosphere through velocity reduction and ablation. These data are justified for use in Section 4.5.3.4 of Attachment II. The range of values bracketing this atmospheric shielding window varies depending on the composition of the meteor. Hills and Goda (1993, p. 1142 [DIRS 135281]) indicate that the threshold for impact to the surface corresponds to a critical radius of 100 m for a stony asteroid, and 500 m for a comet. For iron meteoroids with initial velocities of 20 km/s, the critical radius is 20 m to 30 m; however, for initial velocities of 11.2 - 15 km/s the critical radius is lowered to about 2 m. Hills and Goda (1993, p. 1140 [DIRS 135281]) indicate that meteors with initial radii of 1 to 5 m can form craters with radii of approximately 50 m to 100 m, if the initial velocity is below 15 km/s. This analysis considers cratering rates for assumed initial velocities of 15 and 20 km/s for all meteors regardless of composition or size. These values are at the lower end of the range of velocities specified by various authors. Given that lower initial values generally yield larger impact craters (Hills and Goda 1993, Figure 17 [DIRS 135281]), the assumption of velocities of 15 and 20 will tend to slightly overestimate the probability of craters of a given size. Available velocity information is discussed in Table 5-1 of the main body of the report. However, as discussed for Assumption 5.4 of the main body of the document, velocities less than 15 km/sec would result in larger crater diameters. There is no indication in the literature of the frequency of occurrence of these very low velocity events, so lower velocities are not further considered because they would not be consistent with available corroborating information. Also, as discussed for Assumption 5.4, this analysis considers all objects to enter the atmosphere at zenith angle zero, and could potentially yield surface impacts. This is a conservative selection, since objects entering at nonzero zenith angles have more kinetic energy absorbed (Hills and Goda, 1998 [DIRS 135291]) as discussed in Assumption 5.4 of the main body of the document. There are no data available relating flux and angle of entry. Furthermore, it is assumed per Assumption 5.4 that the zone of fracturing is cylindrical with depth, rather than parabolic. That is, the extent of the zone of fracturing is at the same depth at the edges of the crater as it is at the center. The modeling work by Hills and Goda (1993, Figure 17 [DIRS 135281]) relates initial meteor radius and initial velocity to the radius of the impact crater produced by the largest fragment (or the residual meteorite). Table II-18 of Attachment II of this analysis report provides the justification for using the relationship between meteor composition, initial meteor radius, initial velocity, and resulting crater radius. It was derived from the curves in Hills and Goda (1993, Figures 16 and 17 [DIRS 135281]) by selecting the velocity curve and initial meteor radius, and reading the corresponding point for the resulting crater radius. Those data were combined with the data presented in Table IV-3 above, to get a distribution for number of events by mass and type, which is shown in Table IV-4, and plotted. Combined plot of these data for 15 km/s and 20 km/s are provided as Figures IV-2a and IV-2b. For events that would result in no crater, a minimum value of 0.1 m was assigned to aid in plotting and calculation. ANL-WIS-MD-000019 REV 01 IV-14 April 2004 Table IV-4. Annualized Number of Events by Type and Crater Radius Number of Events per km2 Mass m (kg) Initial Meteor Radius (m) Crater Radius (m) for 15 km/s Crater Radius (m) for 20 km/s Iron Meteor 3.1E-05 1.00E-01 1.4 E-02 0.10 0.10 9.8E-06 1.00E+00 3.1E-02 0.10 0.10 1.6E-06 1.00E+0 6.7E-02 0.10 0.10 9.8E-07 1.00E+0 1.4E-01 0.60 0.20 1.6E-07 1.00E+0 3.1E-01 4.0 3.0 6.2E-08 1.00E+0 6.7E-01 14 10 9.8E-09 1.00E+0 1.4E+00 40 0.10 9.8E-10 1.00E+0 3.1E+00 5.0 0.10 9.8E-12 1.00E+0 6.7E+00 3.2 0.10 9.8E-13 1.00E+0 1.4E+01 32 0.70 9.8E-14 1.00E+0 3.1E+01 200 60 9.8E-15 1.00E+10 6.7E+01 1,000 400 9.8E-16 1.00E+11 1.4E+02 4,500 3,000 3.1E-16 1.00E+12 3.1E+02 11,000 9,000 9.8E-17 1.00E+13 6.7E+02 27,000 27,000 9.8E-18 1.00E+14 1.4E+03 70,000 90,000 3.1E-18 1.00E+15 3.1E+03 170,000 200,000 Hard Stone Meteors 9.9E-05 1.00E-01 1.9E-02 0.10 0.10 3.1E-05 1.00E+00 4.0E-02 0.10 0.10 5.6E-06 1.00E+0 8.6E-02 0.10 0.10 2.7E-06 1.00E+0 1.9E-01 0.17 0.10 3.1E-07 1.00E+0 4.0E-01 0.75 0.32 9.9E-08 1.00E+0 8.6E-01 7.0 3.0 1.2E-08 1.00E+0 1.9E+00 0.10 0.10 7.8E-10 1.00E+0 4.0E+00 0.10 0.10 3.9E-12 1.00E+0 8.6E+00 0.10 0.10 9.2E-12 1.00E+0 1.9E+01 0.10 0.10 9.2E-13 1.00E+0 4.0E+01 1.0 0.10 9.2E-14 1.00E+10 8.6E+01 100 40 9.2E-15 1.00E+11 1.9E+02 800 700 2.9E-15 1.00E+12 4.0E+02 5,000 5,000 9.2E-16 1.00E+13 8.6E+02 30,000 40,000 9.2E-17 1.00E+14 1.9E+03 70,000 90,000 2.9E-17 1.00E+15 4.0E+03 170,000 200,000 ANL-WIS-MD-000019 REV 01 IV-15 April 2004 Table IV-4. Annualized Number of Events by Type and Crater Radius (Continued) Number of Events per km2 Mass m (kg) Initial Meteor Radius (m) Crater Radius (m) for 15 km/s Crater Radius (m) for 20 km/s Soft Stone Meteors 4.9E-04 1.00E-01 2.8E-02 0.10 0.10 1.5E-04 1.00E+00 6.0E-02 0.10 0.10 2.4E-05 1.00E+01 1.3E-01 0.10 0.10 1.6E-05 1.00E+02 2.8E-01 0.20 0.10 2.6E-06 1.00E+03 6.0E-01 0.10 0.10 1.1E-06 1.00E+04 1.3E+00 0.10 0.10 1.7E-07 1.00E+05 2.8E+00 0.10 0.10 1.8E-08 1.00E+06 6.0E+00 0.10 0.10 1.8E-10 1.00E+07 1.3E+01 0.10 0.10 9.4E-12 1.00E+08 2.8E+01 0.10 0.10 9.4E-13 1.00E+09 6.0E+01 3.0 0.20 9.4E-14 1.00E+10 1.3E+02 280 280 9.4E-15 1.00E+11 2.8E+02 1,000 1,000 3.0E-15 1.00E+12 6.0E+02 20,000 28,000 9.4E-16 1.00E+13 1.3E+03 43,000 70,000 9.4E-17 1.00E+14 2.8E+03 100,000 130,000 3.0E-17 1.00E+15 6.0E+03 210,000 300,000 NOTES: After Hills and Goda (1993, Figures 16 and 17 [DIRS 135281]) Number of events and mass taken from Table IV-2 of this attachment. Initial meteor radius taken from Table IV-3. Crater radius derived directly from Hills and Goda (1993, Figures 16 and 17 [DIRS 135281]; the source for the meteor radius-to- crater diameter relationship (Table II-18 of Attachment II) was justified for use as direct input based on Tables II-19 of Attachment II of this analysis report. ANL-WIS-MD-000019 REV 01 IV-16 April 2004 2 Dilic 1 E-18 1 E-17 1 E-16 1 E-15 1 E-14 1 E-13 1 E-12 1 E-11 1 E-10 1 E-09 1 E-08 1 E-07 1 E-06 1 E-05 1 E-04 Number of Events Per Year per kmp in curves refects atmosphereffects per Hills and Goda 1993, Figures 16 and 17 [135281] 1 E-01 1 E+00 1 E+01 1 E+02 1 E+03 1 E+04 1 E+05 1 E+06 Crater Radius (m) // /lIron Meteors at 15 kmsec Hard Stone Meteors at 15 kmsec Soft Stone Meteors at 15 kmsec Tota Number of Events by Crater Radius Figure IV-2a. Total Number of Events by Type and Crater Radius (15 km/s) ANL-WIS-MD-000019 REV 01 IV-17 April 2004 2 Dil 16 and 1 E-18 1 E-16 1 E-14 1 E-12 1 E-10 1 E-08 1 E-06 1 E-04 Number of Events per Year per km p in curves refects atmospheric effects per Hills and Goda 1993, Figures17 [135281] 1 E-01 1 E+00 1 E+01 1 E+02 1 E+03 1 E+04 1 E+05 1 E+06 Crater Radius (m) // /lIron Meteors at 20 kmsec Hard Stone Meteors at 20 kmsec Soft Stone Meteors at 20 kmsec Tota Number of Events by Crater Radius Figure IV-2b. Total Number of Events by Type and Crater Radius (20 km/s) ANL-WIS-MD-000019 REV 01 IV-18 April 2004 The difficulty with relating the impact events by mass and type (Table IV-4) to a singular probability for a given crater diameter is that for a given initial velocity, meteors of equal initial radius but differing compositions result in different crater diameters. In addition, meteors with different initial radii but the same composition can result in equal crater diameters. A method was needed to determine the number of impact events resulting in crater diameter “D” by composition and to sum the number of possible events resulting in crater diameter “D” regardless of meteor composition or radius of the initial meteor. A graphical method was chosen to sum the number of cratering events of diameter “D” or larger. Once the curves for each of the three types of meteors were plotted, the cumulative number of cratering events was read for each composition for a range of crater radius from 0.1 m to 200 km. The total number of events for each crater radius size was manually summed (Table IV-5). The total number of events by crater radius is shown on the Figures IV-2a and IV-2b. 2.2.4.5 Resulting Cratering Distribution The cratering distribution curves for 15 km/s and 20 km/s from Figures IV-2a and IV-2b based on the modeling results from Hills and Goda (1993, Figures 16 and 17 [DIRS 135281]) are shown on Figure IV-3. Figure IV-3 allows comparison to the distribution curves derived from Grieve (1987 [DIRS 135254]); Wuschke et al. (1995 [DIRS 129326]); and for corroboration with Neukum and Ivanov (1994 [DIRS 121510]); all from Figure IV-1. The cumulative curves from Figure IV-2a and IV-2b have been plotted as crater diameter (km), rather than crater radius (m), to allow comparison to the earlier figure. The translation from meteor radius to crater diameter, along with the total number of events for each crater diameter, are shown in Table IV-5. There is good agreement in the curves for crater diameters greater than 10 km, which is the stated limit for Grieve distribution, and for the portion of the curves less than 0.02 km for V=15 km/sec, and for the portion of the curve less than 0.1 km for V=15 k/sec. However, the range of crater diameter of primary interest is roughly from 0.08 km to 0.6 km (79 m to 625 m) based both on the probability threshold and potential for effects on the repository. The distributions show the greatest divergence in this range. ANL-WIS-MD-000019 REV 01 IV-19 April 2004 Table IV-5. Annualized Total Number of Events by Crater Radius and Diameter Crater Radius (m) Crater Diameter D (km) Annualized Frequency (F) for V = 15 km/s Annualized Frequency (F) for V = 20 km/s 0.002 8.5E-07 5.6E-07 0.004 5.1E-07 4.3E-07 0.006 4.3E-07 2.9E-07 0.008 3.6E-07 1.7E-07 0.010 3.2E-07 1.5E-07 0.012 3.0E-07 1.4E-07 0.014 1.9E-07 1.4E-07 0.016 8.7E-08 1.3E-07 0.018 8.2E-08 1.2E-07 0.020 7.7E-08 6.2E-08 20 0.040 3.4E-08 5.0E-13 30 0.060 2.7E-08 4.3E-13 Crater Radius (m) 40 0.080 9.8E-09 3.9E-13 50 0.10 8.5E-13 3.7E-13 60 0.12 7.3E-13 3.3E-13 70 0.14 6.1E-13 2.8E-13 80 0.16 5.4E-13 2.5E-13 90 0.18 4.9E-13 2.2E-13 100 0.20 4.5E-13 2.0E-13 200 0.40 2.5E-13 1.5E-13 300 0.60 1.6E-13 1.1E-13 400 0.80 1.1E-13 7.5E-14 500 1.0 7.3E-14 4.9E-14 600 1.2 6.0E-14 3.9E-14 700 1.4 4.7E-14 3.4E-14 800 1.6 3.6E-14 2.6E-14 900 1.8 3.1E-14 2.3E-14 1,000 2.0 2.6E-14 1.9E-14 2,000 4.0 1.5E-14 1.4E-14 3,000 6.0 1.2E-14 1.1E-14 4,000 8.0 9.8E-15 9.8E-15 5,000 10 8.7E-15 9.0E-15 6,000 12 8.1E-15 7.9E-15 7,000 14 7.0E-15 7.5E-15 8,000 16 6.6E-15 6.9E-15 9,000 18 6.4E-15 6.5E-15 10,000 20 6.1E-15 6.1E-15 20,000 40 4.4E-15 4.6E-15 30,000 60 2.7E-15 3.9E-15 40,000 80 1.4E-15 3.0E-15 ANL-WIS-MD-000019 REV 01 IV-20 April 2004 Table IV-5. Annualized Total Number of Events by Crater Radius and Diameter (Continued) Crater Diameter D (km) Annualized Frequency (F) for V = 15 km/s Annualized Frequency (F) for V = 20 km/s 50,000 100 8.3E-16 1.9E-15 60,000 120 5.5E-16 1.5E-15 70,000 140 3.5E-16 1.2E-15 80,000 160 2.5E-16 7.3E-16 90,000 180 1.9E-16 5.0E-16 100,000 200 1.6E-16 3.9E-16 200,000 400 5.3E-17 8.2E-17 NOTE: These are the supporting values used to plot Figures IV-5a and IV-5b. The two right hand columns represent the total number of cratering events per year per km2 for initial velocities of 15 km/s and 20 km/s respectively and were derived by summing the number of events from each meteor type for a given crater radius. 1.0E-17 1.0E-16 1.0E-15 1.0E-14 1.0E-13 1.0E-12 1.0E-11 1.0E-10 1.0E-09 1.0E-08 1.0E-07 1.0E-06 1.0E-05 Number of Events per Year per km2 istribution for 15 km/sec, after modeling by Hikm/sec, after modeling by HiGrieve (1987 and 1995, extrapolated for D < 10 km) [DIRS 135254], [DIRS 135260] Wuschke et al. 1995 (extrapolated for D , 0.5 km) [DIRS 129326] Neukum and Ivanov 1994 (for atmosphereless earth) [DIRS 121510] Cratering Dlls and Goda 1993 [DIRS 135281] Cratering distribution for 20 lls and Goda 1993 [DIRS 135281] 0.001 0.01 0.1 1 10 100 Crater Diameter (km) NOTE: This figure compares the results of the mass flux distributions given in Table IV-5 to plots based on lunar cratering data (for an atmosphereless earth) and observed earth cratering data as previously provided in Figure IV-1. Figure IV-3. Comparison of Cratering Distribution Based on Meteoroid Flux to Cratering Distributions of Others ANL-WIS-MD-000019 REV 01 IV-21 April 2004 2.3 PROBABILITY OF A CRATER DIAMETER OF INTEREST OCCURRING WITHIN THE REPOSITORY FOOTPRINT Figure IV-3 represents the range of possible frequencies of impacts resulting in a given or larger crater diameter per km2. All frequency curves fall below the Neukum and Ivanov curve. This is to be expected since the curve derived from Neukum and Ivanov (1994, Table IV [DIRS 121510]) is based on the lunar cratering rate and neglects any atmospheric shielding effects. he The relationship of the Neukum and Ivanov curve to the other curves show that the Neukum and Ivanov curve is an upper bound within the range of interest. As discussed below, the bounding nature is used to divide the mass flux curves and to define the related coefficients and integration limits for those curves. The Neukum and Ivanov curve is not further used in the probability calculations, since it would unrealistically overestimate the frequency of occurrence. 2.3.1 Footprint To apply the distributions described above to the TSPA-LA repository, it is necessary to define the target area and the depths of interest, adjust the target area for “near misses,” and integrate the distributions over the range of possible crater diameters. 2.3.2 TSPA-LA Repository Footprint and Other Target Areas Potential target areas to be used for FEP screening, include the TSPA-LA emplacement area footprint and the outcrop of the Paintbrush geologic unit. For corroboration and sensitivity analysis the TSPA-SR footprint and the TSPA-LA siting area are also of potential interest. These various repository and siting area footprints are given on Figure IV-4a. Figure IV-4b show the outlines of the TSPA-LA siting area, the drift layout for the TSPA-LA, and nearby boring locations. Corroborative probability analyses are performed for the TSPA-SR footprint and for the TSPA-LA siting area. ANL-WIS-MD-000019 REV 01 IV-22 April 2004 Figure IV-4a. TSPA-SR Repository Footprint and TSPA-LA Siting Area Source: 800-P0C-MGR0-00100-00E, Figure 1 [DIRS 165572] ANL-WIS-MD-000019 REV 01 IV-23 April 2004 Figure IV 4b. TSPA-LA Siting Area Source: 800-P0C-MGR0-00100-00E, Figure II-4 [DIRS 165572] Figure IV-4. Comparison of TSPA-SR and TSPA-LA Repository Footprints and Drift Layouts 2.3.2.1 TSPA-LA Repository Footprint The analysis for TSPA-LA uses the footprint for the emplacement area for direct input. As represented in Drawing 800-IED-WIS0-00101-000-00A (BSC 2004 [DIRS 164519]), the maximum extent of the drifts is shown in Table IV-6. Table IV-6. Drift End Coordinates Drift End Coordinate Drift Number and Basis (meters) (3-1W) northernmost drift end N236237 (2-27) southernmost drift end N230944 (3-2E) easternmost drift end E172231 (4-20) westernmost drift end E170085 ANL-WIS-MD-000019 REV 01 IV-24 April 2004 This results in the following rough dimensions and total surface area. North/South Length (L) East/West Width (W) Approximate Area (A) (236237 m-230944 m) = 5.3 km (172231m-170085m) = 2.2 km 5.3 km x 2.2 km = 11.6 km2 The measured distances are rounded upward to the nearest tenth of a kilometer, and the rounding is inconsequential because a rectangular repository area is used as a calculation simplification. Also, a 0.1 km was added to the repository length to add distance to account for the construction ramp location. Using the adjusted value of 5.4, the rectangular area is approximately 11.9 km2. Use of a rectangular area and adjustments of lengths as simplifications will result in an conservative overestimation of the repository emplacement area by a factor of about 2. In actuality, the area of the repository drifts, as seen in Figure IV-2b is irregularly shaped. For the emplacement area shown on Figure IV-4b above and as given in 800-IED-WIS0-00103-000-00A (BSC 2004 [DIRS 168370]), the total of the emplacement area is given as 6,004,074 m2, or an equivalent 6.0 km2. 2.3.2.2 Paintbrush Outcrop This target area is pertinent for TSPA-LA because the Paintbrush is a key geologic unit. For TSPA-SR, the area of the repository lying below the Paintbrush outcrop area along the western edge of the repository footprint was determined to be 1.1 km by 0.1 km (BSC 2002, Table 4 and Section 6.5.1.3 [DIRS 159124]). This portion of the analysis was retained for completeness, although the change in repository footprint from TSPA-SR to TSPA-LA shifted the repository eastward, away and from beneath the outcrop. This change in footprints can be seen by comparing Figures IV-4a and 4b above. 2.3.2.3 TSPA-LA–Siting Area A corroborative analysis is performed using estimated dimensions for the siting area as taken from Figure IV-4a above. Consideration of the entire siting area increases the general area and aids in determining the sensitivity of the analysis to changes in repository footprint design. Knowledge of such sensitivity may allow application of this analysis without revision in the event the repository footprint is changed. The reference drawing shows the extent of the entire siting area. The estimated dimensions are: North/South Length (L) East/West Width (W) Approximate Area (A) (236500 m-230500 m) = 6.0 km (173000 m-170000 m) = 3.0 km 6.0 km x 3.0 km = 18.0 km2 2.3.2.4 TSPA-SR Repository Footprint The corroborative analysis for the TSPA-SR repository footprint has been retained in this analysis report because the TSPA-SR design, less the contingency area, is roughly equivalent to the longest dimension of the repository footprint to be used as the basis of the TSPA-LA. This provides a basis for examining the sensitivity of the analysis to changes in relative dimensions. The area and depth of the TSPA-SR repository was based on the design provided in CRWMS M&O (2000 [DIRS 150088]). For TSPA-SR meteor evaluation, a conservative bounding ANL-WIS-MD-000019 REV 01 IV-25 April 2004 assumption regarding the repository footprint was used and was based on the shallowest depth of the repository and the largest areal footprint. The TSPA-SR meteorite FEP evaluation assumed that the repository dimensions were: North/South Length (L) East/West Width (W) Approximate Area (A) Minimum Depth 8.6 km1.3 km 8.6 km x 1.3 km = 11.2 km2 250 m This length and width for the drift layouts are shown in Figure IV-4a and exclude turn outs for the access drifts. The lower block was not considered in the TSPA-SR evaluation. For this analysis, the length and width values are retained. However, the minimum depth of the emplacement area is assumed to be 200 m to ensure equivalence for comparison to the TSPA-LA design. 2.3.3 Depths and Crater Diameters of Interest The depths and crater diameters of interest include the diameter associated with the onset of complex cratering, the depth to the Paintbrush geologic unit, and the depth to the repository. 2.3.3.1 Simple and Complex Cratering The amount of meteor kinetic energy acting in combination with the impacted rock properties determines the features, shape, size, and depth of any crater and any related cratering effects such as fracturing. The potential consequences are divided at the first level based on two types of observed cratering. Simple craters consist of an elevated rim and central depression. Complex cratering involves the uplift and significant vertical displacement of the central portion of the crater. Complex cratering can be initiated with crater diameters of 2 km in sedimentary rocks; however, terrestrial simple craters may also exhibit crater diameters up to 4 km, which is the threshold for simple-to-complex cratering in crystalline rocks based on the direct inputs justified for use in Section 4.5.3.4 of Attachment II (Grieve 1987, p. 249 [DIRS 135254]; Grieve et al. 1995, p. 184 [DIRS 135260]; Wuschke et al. 1995, p. 3 [DIRS 129326]). The threshold for FEP screening based on probability is stated as an annualized equivalence of 10-8 events per year for the repository area (Assumption 5.1 of the main body of this document). Based on the cratering rate distributions given in Figure IV-3, a 2-km crater diameter occurs at a frequency of approximately 10-12 or less per year, which is four orders of magnitude less frequent than the threshold for consideration. Consequently, complex cratering features, which can onset at a crater diameter of 2 km, do not occur with sufficient frequency to be of concern for FEP screening. Because such large diameter craters are very unlikely events, complex cratering is not further considered in the FEP analysis. 2.3.3.2 Depth of the Paintbrush Unit and Related Crater Diameters As referenced in BSC 2003, Sections 6.1.2 and 6.2.2 [DIRS 168027], geologic information relevant to the assessment of the repository includes the thickness and continuity of the PTn unit lying above the repository unit. The large storage capacity and low fracture frequency of the highly porous PTn unit may effectively dampen transient pulses of infiltration and more evenly distribute the downward flow of water. However, isotopic (chlorine-36) analysis has identified ANL-WIS-MD-000019 REV 01 IV-26 April 2004 isolated pathways that provide relatively rapid water movement for small amounts of water through the Paintbrush non-welded unit to the top of the underlying Topopah Springs welded unit. Geologic data indicate that the PTn ranges in thickness from greater than 165 m (541 feet) beneath northern Yucca Mountain to about 15 m (49 feet) in the south, with breaks in area coverage along the Solitario Canyon, Iron Ridge, and Dune Wash fault systems. The underground layout incorporates a minimum PTn thickness of 10 m (33 feet). However, the primary information relevant to this analysis is the depth of the PTn below the surface, because the depth to the top of the geologic unit is used to define the maximum crater diameter, or more specifically the associated depth of increased fracturing, that can occur without the potential to significantly change the subsurface hydrogeologic fracture properties. The depth of this unit, then, is of interest. Figures IV-4b and IV-5 references the location of various boreholes in relation to the repository footprint and the local coordinates. Starting with the borehole locations shown, the following inputs were used to determine the depth to sub-zones of the Paintbrush non-welded unit. The zones of interest include the Pah Canyon and Topopah Springs subzones of the Paintbrush non- welded tuff. The depths of lithostratigraphic contacts are taken from MO0004QGFMPICK.000 (BSC 2003 [DIRS 152554]) and are given in Table IV-7. The data are arranged by increasing depth to the top of the Pah Canyon (Tpp) unit. Across most of the TSPA-LA repository footprint, the Tpp unit is at depths of 60 m or greater, based on the average and 50th percentile values for the depth to the top of the Tpp unit. At all locations given, with the exception of the locations USW WT-14, USW UZ-N31, UE-25 p #1, and USW UZ-N32 (shaded in Table IV-7), the depth of the Tptrv3 unit is greater than 60 m.A range of exhumation depth–to–crater diameter ratios of 0.10 to 0.33 is noted in Attachment II, and a value of 0.32 has been justified for use as direct input in Section 4.5.3.5 of Attachment II. These ratios are based on direct input provided in Wushcke et al. (1995 [DIRS 129326] and Grieve (1998 [DIRS 163385]). A value for fracture depth–to–crater diameter of 0.32 is realistic based on Grieve (1998 [DIRS 163385]). Because the intended use is for FEP screening and analysis, the conservative value of increased fracturing depth to 0.76 of the crater diameter, as indicated by Wuschke et al. (1995 [DIRS 129326]), is examined to ensure that the range of uncertainty in relationships is covered. The use of this value based on effects in plutonic rock is somewhat contrary to the observation made by Grieve (1998, p. 113 [DIRS 163385]) that depths in sedimentary rocks tend to be shallower than in plutonic rock. However, the use of these values is consistent with use of cratering rate and crater diameter distributions from these same sources. A more complete discussion is provided in Section 4.5.3.5 of Attachment II. Given a 60-m depth to a key hydrogeologic unit, and given the depth–to–crater diameter ratios just stated, the crater diameters of concern for exhumation for the PTn unit ranges from 188 to 600 m, and the crater diameters of interest with regard to fracturing is about 79 m. ANL-WIS-MD-000019 REV 01 IV-27 April 2004 Source: BSC 2004, Figure 4 [DIRS 168029] Figure IV-5. Boring Locations ANL-WIS-MD-000019 REV 01 IV-28 April 2004 Table IV-7. Depth to PTn in the TSPA-LA Repository Area Statistic/Boring Pah Canyon Tuff nondivided (Tpp) Topopah Spring Tuff (Tpt) crystal-rich vitric nonwelded to partially welded zones (Tptrv3) Tpt, crystal-rich vitric densely welded zone (Tptrv1) Thickness (m)Depth from Surface (m) Summary Statistics Maximum 281.6 290.8 294.7 83.1 Average 88 109 112 24 50th Percentile 68 92 97 17 Minimum 31.1 32.6 37.8 5.2 By Boring USW UZ-14 31.1 81.7 86.1 55.0 USW UZ-1 32.0 82.9 86.6 54.6 USW WT-14 32.6 32.6 37.8 5.2 USW UZ-N31 36.5 51.3 55.2 18.8 UE-25 p #1 38.7 42.7 45.1 6.4 USW UZ-N32 39.6 56.7 60.8 21.2 USW G-1 41.1 80.8 82.3 41.1 USW UZ-N37 45.2 74.6 78.2 33.1 USW SD-9 47.4 77.9 81.8 34.4 USW G-4 51.3 68.3 72.8 21.6 UE-25 NRG #7/7a 52.4 86.7 90.3 37.9 UE-25 UZ #4 53.0 101.5 105.2 52.2 UE-25 NRG #6 53.3 74.6 79.2 25.9 UE-25 a #5 54.9 79.9 84.4 29.6 UE-25 a #6 56.7 70.0 73.7 17.0 UE-25 UZ #5 56.7 105.2 108.1 51.4 UE-25 UZ #16 57.5 66.1 69.9 12.4 USW H-1 58.0 89.9 100.6 42.6 USW UZ-N54 58.3 66.3 70.9 12.6 USW UZ-N53 59.6 67.3 70.1 10.5 UE-25 a #4 60.0 92.0 96.6 36.5 UE-25 b #1 62.3 78.9 83.8 21.5 USW UZ-7a 65.5 74.1 75.8 10.3 UE-25 NRG #5 65.5 97.8 100.6 35.1 USW H-4 65.8 73.8 76.5 10.7 USW WT-17 66.1 73.8 75.6 9.4 UE-25 a #1 66.5 81.3 84.0 17.5 USW UZ-N55 67.5 71.1 74.4 6.8 UE-25 a #7 69.0 89.0 92.8 23.8 USW WT-2 75.3 82.6 85.3 10.1 UE-25 c #3 82.6 87.2 90.8 8.2 USW H-6 84.7 91.5 100.6 15.8 USW SD-12 84.8 95.7 98.9 14.1 UE-25 NRG #2b 87.0 ANL-WIS-MD-000019 REV 01 IV-29 April 2004 Table IV-7. Depth to PTn in the TSPA-LA Repository Area (Continued) Topopah Spring Tuff Statistic/Boring Pah Canyon Tuff nondivided (Tpp) (Tpt) crystal-rich vitric nonwelded to partially welded zones (Tptrv3) Tpt, crystal-rich vitric densely welded zone (Tptrv1) Thickness (m) UE-25 c #2 87.2 93.3 96.0 8.8 USW WT-11 87.5 93.6 96.6 9.1 UE-25 c #1 91.4 97.2 100.3 8.8 USW WT-4 98.8 135.3 139.0 40.2 USW WT-12 103.3 110.3 112.5 9.1 USW SD-7 104.5 117.1 117.7 13.2 USW WT-15 113.4 132.9 134.7 21.3 UE-25 NRG #4 114.3 145.4 147.8 33.5 USW WT-7 119.2 126.5 131.7 12.5 USW GU-3/G-3 119.4 127.3 130.4 11.0 USW H-3 127.1 132.6 135.6 8.5 USW WT-1 135.9 145.4 147.5 11.6 USW UZ-6 137.2 145.8 149.0 11.9 USW WT-13 140.2 149.4 151.8 11.6 USW WT-16 140.8 176.8 181.1 40.2 USW H-5 143.6 165.2 171.3 27.7 USW WT-24 144.5 212.0 212.4 68.0 USW G-2 150.6 230.2 233.7 83.1 USW WT-18 151.5 210.9 213.7 62.2 UE-25 ONC #1 189.3 196.0 199.3 10.1 UE-25 J-13 198.1 207.9 210.6 12.5 USW WT-10 281.6 290.8 294.7 13.1 Source: DTN MO0004QGFMPICK.000 (BSC 2003 [DIRS 152554]) 2.3.3.3 Depth of the Repository Emplacement Area and Related Crater Diameters With regard to the depth of the repository emplacement area, the minimum stand-off distances given in Drawing 800-IED-WIS0-00101-000-00A (BSC 2004 [DIRS 164519]) indicates that the overburden thickness from emplacement area to topographic surface is 215 m. A slightly shallower depth of 200 m will be used in the calculation to provide a small margin of conservatism and to allow for any future eastward extension or additions of drifts within the siting area. A range of exhumation depth–to–crater diameter–to–ratios of 0.10 to 0.33 is noted in Attachment II, and a value of 0.32 has been justified for use as direct input in Section 4.5.3.5 of Attachment II, as previously discussed. Because the intended use is for FEP screening and analysis, the conservative value of increased fracturing depth to 0.76 of the crater diameter, as indicated by Wuschke et al. (1995 [DIRS 129326]), is examined to ensure that the range of uncertainty in relationships is covered. ANL-WIS-MD-000019 REV 01 IV-30 April 2004 Given the above ratios, the crater diameters of interest for impairing repository performance from exhumation to repository depth ranges from 625 m to about 2 km, and craters capable of fracturing to repository depth have diameters in excess of about 263 m. 2.3.4 Cratering Distributions Adjusted for Target Area The target area in each case is initially assumed rectangular in shape, with the dimensions described in Section 2.3.1 of this attachment. However, if a meteorite were to impact exterior to the repository boundary or an outcrop area, but within one-half of the crater diameter from the boundary, the repository could still potentially be affected. This affects the boundaries on each side of the repository and the outcrop. Assuming fracturing and exhumation effects are cylindrical below the entire crater, the target area can be expressed as: Area (A) = (L + 2 x D/2)(W + 2 x D/2) = (L+D)(W+D) (Eq. IV-6) Equation 6 further simplifies to Area (A) = LW + (L+W)D + D2 (Eq. IV-6a) where: L = length of target area (km) W = width of target area (km) D = diameter of crater (km). Starting with Equation IV-1, the overall annual probability of meteorite impacts that could disrupt or fracture the repository is given by the product of the frequency of impact and the target area integrated over the range of possible crater diameters: F = . f(D) A dD (Eq. IV-7) From Equations IV-2 and IV-6a and with k equaling the power of the distribution for a given meteorite crater distribution: F = . (-k K Dk-1) (LW + (L+W) D + D2) dD (Eq. IV-8) By removing the constants k and K and using the additive properties of integrals and exponents, the resulting integral is in the form of . un du F = -k K . (LWDk-1 + (L+W)Dk + D k+1) dD (Eq. IV-8a) ANL-WIS-MD-000019 REV 01 IV-31 April 2004 Equation IV-8a simplifies to: 300 F = -k K LW(D)k + (L+W)(D)k+1+ (D)k+2 (Eq. IV-8b) k k+1 k+2 D where: F = frequency of impacts per year capable of disrupting the repository K = the proportionality constant (from regression analysis) k = power of the distribution (from regression analysis) L = length of the repository (km) W = width of the repository (km) D = diameter of the crater (km). The lower limit to the integral is assumed to be 0.001 km (1 m), based on the need to capture very small crater diameters to evaluate the potential for impact in the PTn outcrop area. . The choice is arbitrary based on the possible scale of interest, and larger or smaller values could have been chosen. The upper limit was set at 300 km, which corresponds to the largest recognized crater on the earth’s surface. A smaller limit could have been set, but would have reduced the cumulative frequency slightly. So long as the diameter is chosen such that the chosen crater diameter occurs at an annualized frequency well below the FEP screening threshold of 10-8, it makes only a minor difference in the resulting calculation. However, a 300 km crater diameter is the largest observed feature on earth, so it serves as a defensible upper bound. Equation IV-4 is coupled with Equation IV-6a to construct a distribution from the equation given by Wuschke et al. (1995, p. 4 [DIRS 129326]), and takes on the form of F(D) = 2.0×10-12 (D)-2 (L + D) (W + D) (Eq. IV-9) 2.3.5 Calculation of Cratering Distribution for the Repository Footprint Equation IV-8b is applied below for the target area for both the Grieve distribution and the distribution based on mass flux. The power of (–1.8) and the value for K of (1.2 + 0.6)×10-12 shown in Equation 3, are only applicable to the Grieve distribution and are used accordingly. As seen on Figure IV-3, the cratering distribution derived from meteoroid flux (after Hills and Goda) has two primary components, an upper curve (for D < 0.1 km) and a lower curve (for D > 0.1 km), which are connected by an essentially vertical portion of the curve. Tables IV-8a through IV-8d provide the results of the regression analyses for the meteoroid flux distributions (i.e., for the upper and lower portions of the frequency curves for 15 and 20 km/s, respectively). Figures IV-6a through IV-6d provide representation of the analysis. Because of the offset in the cumulative-flux-derived frequency curves, the constant, K, was also determined for each portion of the curve for each velocity. Table IV-9 provides example spreadsheet calculations for the results shown in Tables IV-8a through IV-8d. ANL-WIS-MD-000019 REV 01 IV-32 April 2004 The slope of the distribution and the constant were applied to Equation IV-8b for the upper and lower portion of the curves for the two atmospheric entry velocities (V=15 km/s and 20 km/s). The use of the two portions of the curve is justified because the lower portion of the meteoroid flux curve indicates a differing distribution as shown on Figure IV-3. For the upper portion of the curves, the lower limit of the integral was taken to be a lower limit of 1 m, as previously described. The upper limit for the integral for the upper portion of the curves was selected based on the breakpoint in the curves for V=15 km/s and V=20 km/s (i.e., based on crater diameters of 80 m and 20 m, respectively). These breakpoints also correspond to the curves approaching the distribution curve given by Neukum and Ivanov (1994 [DIRS 121510]). The Neukum and Ivanov curve was previously defined as an upper bound on crater diameter distribution based on lunar cratering data adjusted for “atmosphereless” earth. Use of an upper integral limit of 300 km for the upper curves would result in a calculated annualized frequency of about 3×10-8 for a crater diameter of 1 km. Figure IV-3 clearly indicates that the value based on three different distribution curves should be on the order of 10-11 or 10-12, a three to four order of magnitude difference. For the lower portion of the curve, the lower integral limit was taken as the breakpoints (80 m and 20 m) in the curves, and an integral limit of a 300-km crater diameter was used, consistent with its application for the Grieve distribution. To address the break in the curve between the upper and lower limits, the calculation overlaps the upper limit for the upper curve respective to the lower limit in the lower curve. This allows for annual frequency of the breakpoint (80 m and 20 m, respectively) to be calculated. The upper limit of the integration is set at 100 m and 40 m respectively, as shown in Tables IV-10a through IV-10d. Using the breakpoint as the upper limit would cause the calculated frequency to be “zero”, because Equation IV-8b is for the cumulative frequency and describes the annual frequency of the given diameter or larger. Tables IV-10a and IV-10b provide the annual probability calculations for cratering above the repository for the TSPA–LA emplacement area, and for the PTn Outcrop area. The results are shown in Figures IV-6 and IV-8, respectively. For corroborative and sensitivity analysis purposes, Table IV-10c evaluates the probability for the TSPA-LA siting area, and for sensitivity analysis purposes, Table IV-10d reassesses the TSPA-SR design. Results are shown for the TSPA-LA siting area and the TSPA-SR design in Figures IV-9 and IV-10, respectively. For the various repository footprint evaluations (Figures IV-7a, IV-7c, and IV-7d), the figures indicate the equivalent FEP screening probability threshold (i.e., an annualized equivalence of 1 × 10-8), the crater diameters that are of interest with respect to fracturing of the Paintbrush hydrologic unit and to depth of the repository, and the crater diameters that are of interest with respect to exhumation of those same features. The diameters of interest for fracturing and exhumation overlap, depending on which feature is being considered and which diameter-to- depth factor is assumed. Figure IV-7b provides the annual probability for cratering in the outcrop area, which is the same for the TSPA–SR and TSPA–LA designs, and the annualized probability for cratering within or near the outcrop area is shown. Because it is the outcrop area(i.e., exposure at the surface) any impact in the outcrop will result in exhumation and fracturing. Tables IV-11 through IV-14 provide example spreadsheet calculations for the results shown in Tables IV-10a through IV-10d, for the distribution curves. ANL-WIS-MD-000019 REV 01 IV-33 April 2004 ANL-WIS-MD-000019 REV 01 IV-34 April 2004 Table IV-8a. Regression Analysis for Crater Diameter D for Meteoroid Flux for Upper Portion of Curve (D <0.1 km) and V = 15 km/s Crater Diameter D15 (km) Frequency (F) log(D) log(F) [log (D) - log (D) mean] [log(D) - log (D)mean]2 [log(F) - log (F)mean] [log(D) - log (D)mean] x [log(F) - log (F)mean] 0.002 8.5E-07 -2.70 -6.07 -0.84 0.71 0.79 -0.67 0.004 5.1E-07 -2.40 -6.30 -0.54 0.29 0.57 -0.31 0.006 4.3E-07 -2.22 -6.37 -0.36 0.13 0.49 -0.18 0.008 3.6E-07 -2.10 -6.44 -0.24 0.06 0.42 -0.10 0.01 3.2E-07 -2.00 -6.49 -0.14 0.02 0.37 -0.05 0.012 3.0E-07 -1.92 -6.52 -0.06 0.00 0.34 -0.02 0.014 1.9E-07 -1.85 -6.72 0.00 0.00 0.14 0.00 0.016 8.7E-08 -1.80 -7.06 0.06 0.00 -0.20 -0.01 0.018 8.2E-08 -1.74 -7.09 0.11 0.01 -0.22 -0.03 0.02 7.7E-08 -1.70 -7.11 0.16 0.03 -0.25 -0.04 0.04 3.4E-08 -1.40 -7.47 0.46 0.21 -0.61 -0.28 0.06 2.7E-08 -1.22 -7.57 0.64 0.40 -0.71 -0.45 0.08 9.8E-09 -1.10 -8.01 0.76 0.58 -1.15 -0.87 Mean -1.86 -6.86 Sum 2.45 -3.00 Slope -1.23 Regression Analysis . [log(D) - log (D)mean] x [log(F) - log (F)mean] Slope = . [log(D) - log (D)mean]2 1.0E-05 1.0E-06 1.0E-07 Note: Values for D and for F are taken from Table IV-7of this attachment. 1.0E-08 Slope = k = -1.23: This is less steep than the Grieve slope of –1.8, 1.0E-09 which is based on observed earth cratering at crater diameters of 10 km Frequency 0.001 0.01 0.1 (events/km2-year) and was extrapolated for smaller crater diameters. The slope of the Grieve Crater Diameter (m) distribution decreases for smaller crater diameters, but is recognized as likely underestimating the number of small diameter craters. Figure IV-6a. Regression Analysis for Upper Curve Portion Constant K = 7.0 E-10 (V= 15 km/s). y = 7E-10x-1.23 R2 = 0.926 Table IV-8b. Regression Analysis for Crater Diameter D for Meteoroid Flux for Lower Portion of Curve (D > 0.1 km) and V = 15 km/s V = 15 km/sec: Lower Portion of Curve . [log(D) - log (D)mean] x [log(F) - log (F)mean] . [log(D) - log (D)mean]2 Regression Analysis Crater Diameter D15 (km) Frequency (F) log(D) log(F) [log(D) - log (D) mean] [log(D) - log (D)mean]2 [log(F) - log (F)mean] [log(D) - log (D)mean] x [log(F) - log (F)mean] 0.1 8.5E-13 -1.00 -12.07 -0.68 0.47 0.73 -0.50 0.12 7.3E-13 -0.92 -12.14 -0.60 0.37 0.66 -0.40 0.14 6.1E-13 -0.85 -12.21 -0.54 0.29 0.58 -0.31 0.16 5.4E-13 -0.80 -12.27 -0.48 0.23 0.53 -0.25 0.18 4.9E-13 -0.74 -12.31 -0.43 0.18 0.49 -0.21 0.2 4.5E-13 -0.70 -12.34 -0.38 0.15 0.45 -0.17 0.4 2.5E-13 -0.40 -12.60 -0.08 0.01 0.19 -0.02 0.6 1.6E-13 -0.22 -12.80 0.09 0.01 -0.01 0.00 0.8 1.1E-13 -0.10 -12.98 0.22 0.05 -0.18 -0.04 1 7.3E-14 0.00 -13.14 0.32 0.10 -0.34 -0.11 1.2 6.0E-14 0.08 -13.22 0.40 0.16 -0.43 -0.17 1.4 4.7E-14 0.15 -13.33 0.46 0.21 -0.53 -0.25 1.6 3.6E-14 0.20 -13.44 0.52 0.27 -0.64 -0.34 1.8 3.1E-14 0.26 -13.51 0.57 0.33 -0.71 -0.41 2 2.6E-14 0.30 -13.58 0.62 0.38 -0.79 -0.48 Mean -0.32 -12.80 Sum 3.19 -3.65 Slope -1.14 Slope = NOTE: Values for D and for F are taken from Table IV-7 of this y = 7E-14x-1.14 1.00E-11 Frequency 1.00E-12 attachment. (events/km2-year) 1.00E-13 Slope = k = -1.14: This is less steep than the Grieve slope of –1.8, which 1.00E-14 is based on observed earth cratering at crater diameters of 10 km and was 1.00E-15 extrapolated for smaller crater diameters. The slope of the Grieve 0.11 10 distribution decreases for smaller crater diameters, but is recognized as Crater Diameter (m) likely underestimating the number of small diameter craters. Constant K = 7.0 E-14 Figure IV-6b. Regression Analysis for Lower Curve Portion (V= 15 km/s) ANL-WIS-MD-000019 REV 01 IV-35 April 2004 R2 = 0.9894 Table IV-8c. Regression Analysis for Crater Diameter D for Meteoroid Flux for Upper Portion of Curve (D < 0.02 km) and V = 20 km/s Crater Diameter [log(D) - log D20 (km) Frequency (F) log(D) log(F) [log(D) - log (D) mean] [log(F) - log (F)mean] [log(D) - log (D)mean] x [log(F) - log (F)mean] (D)mean]2 0.002 5.6E-07 -2.70 -6.26 -0.66 0.43 0.49 -0.32 0.004 4.3E-07 -2.40 -6.36 -0.35 0.13 0.38 -0.14 0.006 2.9E-07 -2.22 -6.53 -0.18 0.03 0.22 -0.04 0.008 1.7E-07 -2.10 -6.76 -0.05 0.00 -0.01 0.00 0.01 1.5E-07 -2.00 -6.83 0.04 0.00 -0.08 0.00 0.012 1.4E-07 -1.92 -6.85 0.12 0.01 -0.11 -0.01 0.014 1.4E-07 -1.85 -6.87 0.19 0.04 -0.12 -0.02 0.016 1.3E-07 -1.80 -6.89 0.25 0.06 -0.15 -0.04 0.018 1.2E-07 -1.74 -6.91 0.30 0.09 -0.16 -0.05 0.02 6.2E-08 -1.70 -7.21 0.34 0.12 -0.46 -0.16 -2.04 -6.75 0.91 -0.78 -0.85 Mean Sum Slope Regression Analysis 1.0E-05 1.0E-06 Frequency . [log(D) - log (D)mean] x [log(F) -log (F)mean] Slope = (events/km2-year) . [log(D) - log (D)mean] 2 1.0E-07 NOTE: Values for D and for F are taken from Table IV-7 of this attachment. 1.0E-08 Slope = k = -0.85: This is less steep than the Grieve slope of –1.8, which is 0.001 0.01 0.1 1 based on observed earth cratering at crater diameters of 10 km and was extrapolated for smaller crater diameters. The slope of the Grieve distribution decreases for smaller crater diameters, but is recognized as likely underestimating the number of small diameter craters. Figure IV-6c. Regression Analysis for Upper Curve Portion (V= 20 km/s) Constant K = 3.0 E-9 ANL-WIS-MD-000019 REV 01 IV-36 April 2004 -0.85 R2 = 0.9127 y = 3E-09x Table IV-8d. Regression Analysis for Crater Diameter D for Meteoroid Flux for Lower Portion of Curve (D > 0.02 km) and V = 20 km/s Crater Diameter D20 (km) Frequency (F) log(D) log(F) [log(D) - log (D) mean] [log(D) - log (D)mean]2 [log(F) - log (F)mean] [log(D) - log (D)mean] x [log(F) - log (F)mean] 0.04 5.0E-13 -1.40 -12.30 -0.93 0.86 0.62 -0.57 0.06 4.3E-13 -1.22 -12.37 -0.75 0.57 0.55 -0.41 0.08 3.9E-13 -1.10 -12.41 -0.63 0.39 0.51 -0.32 0.1 3.7E-13 -1.00 -12.44 -0.53 0.28 0.48 -0.25 0.12 3.3E-13 -0.92 -12.48 -0.45 0.20 0.44 -0.20 0.14 2.8E-13 -0.85 -12.56 -0.38 0.15 0.36 -0.14 0.16 2.5E-13 -0.80 -12.60 -0.33 0.11 0.32 -0.10 0.18 2.2E-13 -0.74 -12.65 -0.27 0.08 0.27 -0.07 0.2 2.0E-13 -0.70 -12.70 -0.23 0.05 0.22 -0.05 0.4 1.5E-13 -0.40 -12.83 0.07 0.01 0.09 0.01 0.6 1.1E-13 -0.22 -12.94 0.25 0.06 -0.03 -0.01 0.8 7.5E-14 -0.10 -13.13 0.37 0.14 -0.21 -0.08 1 4.9E-14 0.00 -13.31 0.47 0.22 -0.39 -0.18 1.2 3.9E-14 0.08 -13.41 0.55 0.30 -0.50 -0.27 1.4 3.4E-14 0.15 -13.47 0.62 0.38 -0.55 -0.34 1.6 2.6E-14 0.20 -13.59 0.67 0.45 -0.67 -0.45 1.8 2.3E-14 0.26 -13.63 0.73 0.53 -0.71 -0.52 2 1.9E-14 0.30 -13.71 0.77 0.59 -0.80 -0.61 Mean -0.47 -12.92 Sum 5.37 -4.58 Slope -0.85 Regression Analysis 1.0E-11 . [log(D) - log (D)mean] x [log(F) -log (F)mean] . [log(D) - log (D)mean] 2 Frequency(events/km2-year) Slope = NOTE: Values for D and for F are taken from Table IV-7of this attachment. Slope = k = -0.85: This is less steep than the Grieve slope of –1.8, which is based on observed earth cratering at crater diameters of 10 km and was extrapolated for smaller crater diameters. The slope of the Grieve distribution decreases for smaller crater diameters, but is recognized as likely underestimating the number of small diameter craters. Constant K = 5.0 E-14 ANL-WIS-MD-000019 REV 01 IV-37 April 2004 -0.85 R2 = 0.9621 1 10 ) Figure IV-6d. ) y = 5E-14x1.0E-15 1.0E-14 1.0E-13 1.0E-12 0.01 0.1 Crater Diameter (mRegression Analysis for Lower Curve Portion (V= 20 km/s Table IV-9. Example Spreadsheet Calculation for Regression Analysis Rows/ Columns C D E F G H I J 2 V=15 km/sec: Upper Portion of Curve 3 Crater Diameter D15 (km) Frequency (F) log(D) log(F) [log(D) - log (Dmean)] [log(D) - log (Dmean)]2 [log(F) - log (Fmean)] [log(D) - log (Dmean)] x [log(F) log (F)] 4 5 From Table IV-5 From Table IV-5 =LOG(C5) =LOG(D5) =E5-$E$19 =G5^2 =F5-$F$19 =I5*G5 6 From Table IV-5 From Table IV-5 =LOG(C6) =LOG(D6) =E6-$E$19 =G6^2 =F6-$F$19 =I6*G6 7 From Table IV-5 From Table IV-5 =LOG(C7) =LOG(D7) =E7-$E$19 =G7^2 =F7-$F$19 =I7*G7 8 From Table IV-5 From Table IV-5 =LOG(C8) =LOG(D8) =E8-$E$19 =G8^2 =F8-$F$19 =I8*G8 9 From Table IV-5 From Table IV-5 =LOG(C9) =LOG(D9) =E9-$E$19 =G9^2 =F9-$F$19 =I9*G9 10 From Table IV-5 From Table IV-5 =LOG(C10) =LOG(D10) =E10-$E$19 =G10^2 =F10-$F$19 =I10*G10 11 From Table IV-5 From Table IV-5 =LOG(C11) =LOG(D11) =E11-$E$19 =G11^2 =F11-$F$19 =I11*G11 12 From Table IV-5 From Table IV-5 =LOG(C12) =LOG(D12) =E12-$E$19 =G12^2 =F12-$F$19 =I12*G12 13 From Table IV-5 From Table IV-5 =LOG(C13) =LOG(D13) =E13-$E$19 =G13^2 =F13-$F$19 =I13*G13 14 From Table IV-5 From Table IV-5 =LOG(C14) =LOG(D14) =E14-$E$19 =G14^2 =F14-$F$19 =I14*G14 15 From Table IV-5 From Table IV-5 =LOG(C15) =LOG(D15) =E15-$E$19 =G15^2 =F15-$F$19 =I15*G15 16 From Table IV-5 From Table IV-5 =LOG(C16) =LOG(D16) =E16-$E$19 =G16^2 =F16-$F$19 =I16*G16 17 From Table IV-5 From Table IV-5 =LOG(C17) =LOG(D17) =E17-$E$19 =G17^2 =F17-$F$19 =I17*G17 18 19 Mean =AVERAGE(E5:E17) =AVERAGE(F5:F17) 20 Sum =SUM(H5:H17) =SUM(J5:J17) 21 Slope =J20/H20 ANL-WIS-MD-000019 REV 01 IV-38 April 2004 Annualized Frequency (events per year) 1.0E-04 1.0E-05 1.0E-06 1.0E-07 1.0E-08 1.0E-09 1.0E-10 1.0E-11 1.0E-12 0.001 Crater Diameter (km) 1 10 V=15 km/sec V=20 km/sec Distribution istribution iameters of Fracturing Effects iameters of FEP Screening 0.01 0.1 Wuschke et al. Grieve DCrater DConcern for Crater DConcern for Exhumation Effects Probability Threshold g Figure IV-7. Annualized Frequency of Cratering above the Repository for the TSPA-LA Emplacement Area ANL-WIS-MD-000019 REV 01 IV-39 April 2004 1.0E-12 1.0E-11 1.0E-10 1.0E-09 1.0E-08 1.0E-07 1.0E-06 Annualized Frequency (events per year) V=15 km/sec V=20 km/sec GriDistribution Distribution FEP Screening eve Wuschke et al. Probability Threshold 0.001 0.01 0.1 1 10 Crater Diameter (km) Figure IV-8. Annualized Frequency of Cratering above the Paintbrush Outcrop ANL-WIS-MD-000019 REV 01 IV-40 April 2004 V=15 km/sec 1.0E-04 1.0E-05 V=20 km/sec 1.0E-06 Wuschke et al. 1.0E-07 Distribution Grieve Distribution 1.0E-08 1.0E-09 Crater Diameters of Concern for 1.0E-10 Fracturing Effects Crater Diameters of 1.0E-11 Concern for Exhumation Effects 1.0E-12 FEP Screening 0.001 0.01 0.1 1 10 Probability Crater Diameter (km) Threshold Figure IV-9. Annualized Frequency of Cratering above the Repository for the TSPA-LA Siting Area Annualized Frequency (events per year) ANL-WIS-MD-000019 REV 01 IV-41 April 2004 Annualized Frequency (events per year) V=15 km/sec V=20 km/sec Distribution istribution Difor Fracturing Effects DiFEP Screening 1.0E-12 1.0E-11 1.0E-10 1.0E-09 1.0E-08 1.0E-07 1.0E-06 1.0E-05 1.0E-04 Wushke et al. Grieve Dameters of Concern ameters of Concern for Exhumation Probability Threshold 0.001 0.01 0.1 1 10 Crater Diameter (km) Figure IV-10. Annualized Frequency of Cratering above the Repository for the TSPA-SR Design ANL-WIS-MD-000019 REV 01 IV-42 April 2004 Table IV-10a. Frequency (F) of Cratering Above Repository for TSPA-LA Emplacement Area TSPA-LA Emplacement Area L=5.4 W=2.2 V=15 km/s Crater Diameter D (km) K LWDk k (L+W)(Dk+1) k+1 D k+2 k+2 F(D) (sum of terms) kK(F(D)-F(D)max) UPPER CURVE FOR V=15 km/s K=7.0 E-10 k=-1.23 0.001 7.0E-10 -4.6E+04 -1.6E+02 6.1E-03 -4.6E+04 3.9E-05 0.002 7.0E-10 -2.0E+04 -1.4E+02 1.0E-02 -2.0E+04 1.7E-05 0.005 7.0E-10 -6.4E+03 -1.1E+02 2.1E-02 -6.5E+03 5.4E-06 0.007 7.0E-10 -4.2E+03 -1.0E+02 2.8E-02 -4.3E+03 3.5E-06 0.009 7.0E-10 -3.1E+03 -9.7E+01 3.4E-02 -3.2E+03 2.6E-06 0.01 7.0E-10 -2.7E+03 -9.5E+01 3.6E-02 -2.8E+03 2.2E-06 0.02 7.0E-10 -1.2E+03 -8.1E+01 6.2E-02 -1.3E+03 8.9E-07 0.03 7.0E-10 -7.1E+02 -7.4E+01 8.5E-02 -7.9E+02 4.9E-07 0.04 7.0E-10 -5.0E+02 -7.0E+01 1.1E-01 -5.7E+02 3.0E-07 0.05 7.0E-10 -3.8E+02 -6.6E+01 1.3E-01 -4.5E+02 2.0E-07 0.06 7.0E-10 -3.0E+02 -6.4E+01 1.5E-01 -3.7E+02 1.3E-07 0.07 7.0E-10 -2.5E+02 -6.1E+01 1.6E-01 -3.1E+02 8.1E-08 0.08 7.0E-10 -2.1E+02 -6.0E+01 1.8E-01 -2.7E+02 4.6E-08 0.1 7.0E-10 -1.6E+02 -5.7E+01 2.2E-01 -2.2E+02 0.0E+00 LOWER CURVE FOR V=15 km/s K=7.0 E-14 k=-1.14 0.09 7.0E-14 -1.6E+02 -7.5E+01 1.5E-01 -2.4E+02 3.0E-11 0.1 7.0E-14 -1.4E+02 -7.4E+01 1.6E-01 -2.2E+02 2.8E-11 0.2 7.0E-14 -6.5E+01 -6.7E+01 2.9E-01 -1.3E+02 2.1E-11 0.3 7.0E-14 -4.1E+01 -6.3E+01 4.1E-01 -1.0E+02 1.9E-11 0.4 7.0E-14 -3.0E+01 -6.1E+01 5.3E-01 -9.0E+01 1.8E-11 0.5 7.0E-14 -2.3E+01 -5.9E+01 6.4E-01 -8.1E+01 1.7E-11 0.6 7.0E-14 -1.9E+01 -5.8E+01 7.5E-01 -7.5E+01 1.7E-11 0.7 7.0E-14 -1.6E+01 -5.6E+01 8.6E-01 -7.1E+01 1.6E-11 0.8 7.0E-14 -1.3E+01 -5.5E+01 9.6E-01 -6.8E+01 1.6E-11 0.9 7.0E-14 -1.2E+01 -5.4E+01 1.1E+00 -6.5E+01 1.6E-11 1 7.0E-14 -1.0E+01 -5.4E+01 1.2E+00 -6.3E+01 1.6E-11 2 7.0E-14 -4.7E+00 -4.8E+01 2.1E+00 -5.1E+01 1.5E-11 3 7.0E-14 -3.0E+00 -4.6E+01 3.0E+00 -4.6E+01 1.4E-11 5 7.0E-14 -1.7E+00 -4.3E+01 4.6E+00 -4.0E+01 1.4E-11 10 7.0E-14 -7.5E-01 -3.9E+01 8.4E+00 -3.1E+01 1.3E-11 300 7.0E-14 -1.5E-02 -2.4E+01 1.6E+02 1.3E+02 0.0E+00 ANL-WIS-MD-000019 REV 01 IV-43 April 2004 Table IV-10a. Frequency (F) of Cratering Above Repository for TSPA-LA Emplacement Area (Continued) TSPA-LA Emplacement Area L=5.4 W=2.2 V=20 km/s Crater Diameter D (km) K LWDk k (L+W)(Dk+1) k+1 D k+2 k+2 F(D) (sum of terms) kK(F(D)-F(D)max) UPPER CURVE FOR V=20 km/s K=3.0 E-09 k=-0.85 0.001 3.0E-09 -5.0E+03 1.9E+01 3.1E-04 -5.0E+03 1.2E-05 0.003 3.0E-09 -2.0E+03 2.2E+01 1.1E-03 -2.0E+03 4.5E-06 0.005 3.0E-09 -1.3E+03 2.4E+01 2.0E-03 -1.3E+03 2.7E-06 0.006 3.0E-09 -1.1E+03 2.4E+01 2.5E-03 -1.1E+03 2.3E-06 0.008 3.0E-09 -8.5E+02 2.5E+01 3.4E-03 -8.3E+02 1.6E-06 0.01 3.0E-09 -7.1E+02 2.6E+01 4.4E-03 -6.8E+02 1.3E-06 0.02 3.0E-09 -3.9E+02 2.9E+01 9.8E-03 -3.6E+02 4.5E-07 0.04 3.0E-09 -2.2E+02 3.2E+01 2.2E-02 -1.8E+02 0.0E+00 LOWER CURVE FOR V=20 km/s K=5.0 E-14 k=-0.85 0.03 5.0E-14 -2.8E+02 3.1E+01 1.6E-02 -2.5E+02 4.1E-11 0.04 5.0E-14 -2.2E+02 3.2E+01 2.2E-02 -1.8E+02 3.9E-11 0.05 5.0E-14 -1.8E+02 3.3E+01 2.8E-02 -1.5E+02 3.7E-11 0.06 5.0E-14 -1.5E+02 3.4E+01 3.5E-02 -1.2E+02 3.6E-11 0.07 5.0E-14 -1.3E+02 3.5E+01 4.1E-02 -1.0E+02 3.5E-11 0.08 5.0E-14 -1.2E+02 3.6E+01 4.8E-02 -8.4E+01 3.4E-11 0.09 5.0E-14 -1.1E+02 3.6E+01 5.5E-02 -7.2E+01 3.4E-11 0.1 5.0E-14 -9.9E+01 3.7E+01 6.2E-02 -6.2E+01 3.4E-11 0.2 5.0E-14 -5.5E+01 4.1E+01 1.4E-01 -1.4E+01 3.1E-11 0.3 5.0E-14 -3.9E+01 4.3E+01 2.2E-01 4.6E+00 3.1E-11 0.4 5.0E-14 -3.0E+01 4.5E+01 3.0E-01 1.5E+01 3.0E-11 0.5 5.0E-14 -2.5E+01 4.7E+01 3.9E-01 2.2E+01 3.0E-11 0.6 5.0E-14 -2.2E+01 4.8E+01 4.9E-01 2.7E+01 3.0E-11 0.7 5.0E-14 -1.9E+01 4.9E+01 5.8E-01 3.1E+01 3.0E-11 0.8 5.0E-14 -1.7E+01 5.0E+01 6.7E-01 3.4E+01 2.9E-11 0.9 5.0E-14 -1.5E+01 5.1E+01 7.7E-01 3.6E+01 2.9E-11 1 5.0E-14 -1.4E+01 5.2E+01 8.7E-01 3.9E+01 2.9E-11 2 5.0E-14 -7.7E+00 5.7E+01 1.9E+00 5.1E+01 2.9E-11 3 5.0E-14 -5.5E+00 6.1E+01 3.1E+00 5.8E+01 2.8E-11 5 5.0E-14 -3.5E+00 6.6E+01 5.5E+00 6.7E+01 2.8E-11 10 5.0E-14 -2.0E+00 7.3E+01 1.2E+01 8.3E+01 2.7E-11 300 5.0E-14 -1.1E-01 1.2E+02 6.0E+02 7.2E+02 0.0E+00 ANL-WIS-MD-000019 REV 01 IV-44 April 2004 Table IV-10a. Frequency (F) of Cratering Above Repository for TSPA-LA Emplacement Area (Continued) TSPA-LA Emplacement Area L=5.4 W=2.2 V=20 km/s Crater Diameter D (km) K LWDk k (L+W)(Dk+1) k+1 D k+2 k+2 F(D) (sum of terms) kK(F(D)-F(D)max) GRIEVE DISTRIBUTION K=1.20 E-12 k=1.80 0.001 1.20E-12 -1.7E+06 -2.4E+03 1.3E+00 -1.7E+06 3.6E-06 0.01 1.20E-12 -2.6E+04 -3.8E+02 2.0E+00 -2.7E+04 5.8E-08 0.03 1.20E-12 -3.6E+03 -1.6E+02 2.5E+00 -3.8E+03 8.2E-09 0.04 1.20E-12 -2.2E+03 -1.2E+02 2.6E+00 -2.3E+03 5.0E-09 0.08 1.20E-12 -6.2E+02 -7.2E+01 3.0E+00 -6.9E+02 1.5E-09 0.1 1.20E-12 -4.2E+02 -6.0E+01 3.2E+00 -4.7E+02 1.1E-09 0.3 1.20E-12 -5.8E+01 -2.5E+01 3.9E+00 -7.9E+01 2.0E-10 0.7 1.20E-12 -1.3E+01 -1.3E+01 4.7E+00 -2.1E+01 7.8E-11 1 1.20E-12 -6.6E+00 -9.5E+00 5.0E+00 -1.1E+01 5.8E-11 10 1.20E-12 -1.0E-01 -1.5E+00 7.9E+00 6.3E+00 2.0E-11 100 1.20E-12 -1.7E-03 -2.4E-01 1.3E+01 1.2E+01 7.0E-12 300 1.20E-12 -2.3E-04 -9.9E-02 1.6E+01 1.6E+01 0.0E+00 WUSCHKE ET AL. DISTRIBUTION Crater Diameter (km) Adjusted L (km) Adjusted W (km) Adjusted Area (km2) D-2 F 0.001 5.40 2.20 11.9 1.0E+06 2.4E-05 0.01 5.41 2.21 12.0 1.0E+04 2.4E-07 0.03 5.43 2.23 12.1 1.1E+03 2.7E-08 0.04 5.44 2.24 12.2 6.3E+02 1.5E-08 0.08 5.48 2.28 12.5 1.6E+02 3.9E-09 0.1 5.50 2.30 12.7 1.0E+02 2.5E-09 0.3 5.70 2.50 14.3 1.1E+01 3.2E-10 0.7 6.10 2.90 17.7 2.0E+00 7.2E-11 1 6.40 3.20 20.5 1.0E+00 4.1E-11 10 15.40 12.20 187.9 1.0E-02 3.8E-12 100 105.40 102.20 10771.9 1.0E-04 2.2E-12 300 305.40 302.20 92291.9 1.1E-05 2.1E-12 For distribution curves: max kk+2 F = k K LW(D)+ (L+W)(D)k+1 + (D) k k+1 k+2 0.001 where: F = events per year L = length of repository (km) K = proportionality constant (from regression equation) W = width of the repository (km) k = power of the distribution (from regression equation) D = diameter of crater (km) For Wuschke et al.: F = 2.0 x 10-12 x D-2 x ( Ladjusted x Wadjusted) ANL-WIS-MD-000019 REV 01 IV-45 April 2004 Table IV-10b. Frequency (F) of Cratering in the Paintbrush Outcrop Outcrop Area L=1.1 W=0.1 V=15 km/s Crater Diameter D (km) K LWDk k (L+W)(Dk+1) k+1 D k+2 k+2 F(D) (sum of terms) kK(F(D)-F(D)max) UPPER CURVE FOR V=15 km/s K=7.0 E-10 k=1.23 0.001 7.0E-10 -4.3E+02 -2.5E+01 6.1E-03 -4.5E+02 3.8E-07 0.002 7.0E-10 -1.8E+02 -2.2E+01 1.0E-02 -2.0E+02 1.7E-07 0.005 7.0E-10 -5.9E+01 -1.8E+01 2.1E-02 -7.7E+01 5.7E-08 0.007 7.0E-10 -3.9E+01 -1.6E+01 2.8E-02 -5.6E+01 3.9E-08 0.009 7.0E-10 -2.9E+01 -1.5E+01 3.4E-02 -4.4E+01 2.9E-08 0.01 7.0E-10 -2.5E+01 -1.5E+01 3.6E-02 -4.0E+01 2.6E-08 0.02 7.0E-10 -1.1E+01 -1.3E+01 6.2E-02 -2.4E+01 1.1E-08 0.03 7.0E-10 -6.6E+00 -1.2E+01 8.5E-02 -1.8E+01 6.9E-09 0.04 7.0E-10 -4.6E+00 -1.1E+01 1.1E-01 -1.6E+01 4.5E-09 0.05 7.0E-10 -3.5E+00 -1.0E+01 1.3E-01 -1.4E+01 3.1E-09 0.06 7.0E-10 -2.8E+00 -1.0E+01 1.5E-01 -1.3E+01 2.1E-09 0.07 7.0E-10 -2.3E+00 -9.7E+00 1.6E-01 -1.2E+01 1.4E-09 0.08 7.0E-10 -2.0E+00 -9.4E+00 1.8E-01 -1.1E+01 8.3E-10 0.1 7.0E-10 -1.5E+00 -8.9E+00 2.2E-01 -1.0E+01 0.0E+00 LOWER CURVE FOR V=15 km/s K=7.0 E-14 k=1.14 0.09 7.0E-14 -1.5E+00 -1.2E+01 1.5E-01 -1.3E+01 1.3E-11 0.1 7.0E-14 -1.3E+00 -1.2E+01 1.6E-01 -1.3E+01 1.3E-11 0.2 7.0E-14 -6.1E-01 -1.1E+01 2.9E-01 -1.1E+01 1.3E-11 0.3 7.0E-14 -3.8E-01 -1.0E+01 4.1E-01 -1.0E+01 1.3E-11 0.4 7.0E-14 -2.7E-01 -9.6E+00 5.3E-01 -9.4E+00 1.3E-11 0.5 7.0E-14 -2.1E-01 -9.3E+00 6.4E-01 -8.9E+00 1.3E-11 0.6 7.0E-14 -1.7E-01 -9.1E+00 7.5E-01 -8.5E+00 1.3E-11 0.7 7.0E-14 -1.4E-01 -8.9E+00 8.6E-01 -8.2E+00 1.3E-11 0.8 7.0E-14 -1.2E-01 -8.7E+00 9.6E-01 -7.9E+00 1.3E-11 0.9 7.0E-14 -1.1E-01 -8.6E+00 1.1E+00 -7.6E+00 1.3E-11 1 7.0E-14 -9.6E-02 -8.4E+00 1.2E+00 -7.4E+00 1.3E-11 2 7.0E-14 -4.4E-02 -7.7E+00 2.1E+00 -5.6E+00 1.3E-11 3 7.0E-14 -2.7E-02 -7.2E+00 3.0E+00 -4.3E+00 1.2E-11 5 7.0E-14 -1.5E-02 -6.7E+00 4.6E+00 -2.1E+00 1.2E-11 10 7.0E-14 -6.9E-03 -6.1E+00 8.4E+00 2.3E+00 1.2E-11 300 7.0E-14 -1.4E-04 -3.8E+00 1.6E+02 1.5E+02 0.0E+00 ANL-WIS-MD-000019 REV 01 IV-46 April 2004 Table IV-10b. Frequency (F) of Cratering In the Paintbrush Outcrop (Continued) Outcrop Area L=1.1 W=0.1 V=20 km/s Crater Diameter D (km) K LWDk k (L+W)(Dk+1) k+1 D k+2 k+2 F(D) (sum of terms) kK(F(D)-F(D)max) UPPER CURVE FOR V=20 km/s K=3.0 E-09 k=-0.85 0.001 3.0E-09 -4.7E+01 2.9E+00 3.1E-04 -4.4E+01 1.2E-07 0.002 3.0E-09 -2.6E+01 3.3E+00 7.0E-04 -2.3E+01 6.6E-08 0.005 3.0E-09 -1.2E+01 3.7E+00 2.0E-03 -8.1E+00 2.9E-08 0.007 3.0E-09 -8.9E+00 3.9E+00 2.9E-03 -4.9E+00 2.1E-08 0.009 3.0E-09 -7.2E+00 4.1E+00 3.9E-03 -3.1E+00 1.6E-08 0.01 3.0E-09 -6.5E+00 4.1E+00 4.4E-03 -2.4E+00 1.4E-08 0.02 3.0E-09 -3.6E+00 4.6E+00 9.8E-03 9.6E-01 5.4E-09 0.04 3.0E-09 -2.0E+00 5.1E+00 2.2E-02 3.1E+00 0.0E+00 LOWER CURVE FOR V=20 km/s K=5.0 E-14 k=-0.85 0.03 5.0E-14 -2.6E+00 4.9E+00 1.6E-02 2.3E+00 2.7E-11 0.04 5.0E-14 -2.0E+00 5.1E+00 2.2E-02 3.1E+00 2.6E-11 0.05 5.0E-14 -1.7E+00 5.3E+00 2.8E-02 3.6E+00 2.6E-11 0.06 5.0E-14 -1.4E+00 5.4E+00 3.5E-02 4.0E+00 2.6E-11 0.07 5.0E-14 -1.2E+00 5.5E+00 4.1E-02 4.3E+00 2.6E-11 0.08 5.0E-14 -1.1E+00 5.6E+00 4.8E-02 4.6E+00 2.6E-11 0.09 5.0E-14 -1.0E+00 5.7E+00 5.5E-02 4.8E+00 2.6E-11 0.1 5.0E-14 -9.2E-01 5.8E+00 6.2E-02 5.0E+00 2.6E-11 0.2 5.0E-14 -5.1E-01 6.4E+00 1.4E-01 6.1E+00 2.6E-11 0.3 5.0E-14 -3.6E-01 6.8E+00 2.2E-01 6.7E+00 2.6E-11 0.4 5.0E-14 -2.8E-01 7.1E+00 3.0E-01 7.2E+00 2.6E-11 0.5 5.0E-14 -2.3E-01 7.4E+00 3.9E-01 7.5E+00 2.6E-11 0.6 5.0E-14 -2.0E-01 7.6E+00 4.9E-01 7.9E+00 2.6E-11 0.7 5.0E-14 -1.7E-01 7.7E+00 5.8E-01 8.2E+00 2.6E-11 0.8 5.0E-14 -1.6E-01 7.9E+00 6.7E-01 8.4E+00 2.6E-11 0.9 5.0E-14 -1.4E-01 8.0E+00 7.7E-01 8.7E+00 2.6E-11 1 5.0E-14 -1.3E-01 8.2E+00 8.7E-01 8.9E+00 2.6E-11 2 5.0E-14 -7.1E-02 9.0E+00 1.9E+00 1.1E+01 2.6E-11 3 5.0E-14 -5.1E-02 9.6E+00 3.1E+00 1.3E+01 2.6E-11 5 5.0E-14 -3.3E-02 1.0E+01 5.5E+00 1.6E+01 2.6E-11 10 5.0E-14 -1.8E-02 1.1E+01 1.2E+01 2.4E+01 2.6E-11 300 5.0E-14 -9.9E-04 1.9E+01 6.0E+02 6.2E+02 0.0E+00 ANL-WIS-MD-000019 REV 01 IV-47 April 2004 Table IV-10b. Frequency (F) of Cratering in the Paintbrush Outcrop (Continued) TSPA-SR Repository L=1.1 W=0.1 V=20 km/s Crater Diameter D (km) K LWDk k (L+W)(Dk+1) k+1 D k+2 K+2 F(D) (sum of terms) kK(F(D)-F(D)max) GRIEVE DISTRIBUTION K=1.20E-12 k=-1.80 0.001 1.20E-12 -1.5E+04 -3.8E+02 1.3E+00 -1.6E+04 3.4E-08 0.01 1.20E-12 -2.4E+02 -6.0E+01 2.0E+00 -3.0E+02 6.8E-10 0.03 1.20E-12 -3.4E+01 -2.5E+01 2.5E+00 -5.6E+01 1.5E-10 0.05 1.20E-12 -1.3E+01 -1.6E+01 2.7E+00 -2.7E+01 9.2E-11 0.077 1.20E-12 -6.2E+00 -1.2E+01 3.0E+00 -1.5E+01 6.6E-11 0.1 1.20E-12 -3.9E+00 -9.5E+00 3.2E+00 -1.0E+01 5.6E-11 0.33 1.20E-12 -4.5E-01 -3.6E+00 4.0E+00 -8.5E-02 3.4E-11 0.67 1.20E-12 -1.3E-01 -2.1E+00 4.6E+00 2.4E+00 2.9E-11 1 1.20E-12 -6.1E-02 -1.5E+00 5.0E+00 3.4E+00 2.6E-11 10 1.20E-12 -9.7E-04 -2.4E-01 7.9E+00 7.7E+00 1.7E-11 100 1.20E-12 -1.5E-05 -3.8E-02 1.3E+01 1.3E+01 6.7E-12 300 1.20E-12 -2.1E-06 -1.6E-02 1.6E+01 1.6E+01 0.0E+00 WUSCHKE ET AL. DISTRIBUTION Crater Diameter (km) Adjusted L (km) Adjusted W (km) Adjusted Area (km2) D-2 Frequency (per year) 0.001 1.10 0.10 0.1 1.0E+06 2.2E-07 0.01 1.11 0.11 0.1 1.0E+04 2.4E-09 0.03 1.13 0.13 0.1 1.1E+03 3.3E-10 0.04 1.14 0.14 0.2 6.3E+02 2.0E-10 0.08 1.18 0.18 0.2 1.6E+02 6.6E-11 0.1 1.20 0.20 0.2 1.0E+02 4.8E-11 0.3 1.40 0.40 0.6 1.1E+01 1.2E-11 0.7 1.80 0.80 1.4 2.0E+00 5.9E-12 1 2.10 1.10 2.3 1.0E+00 4.6E-12 10 11.10 10.10 112.1 1.0E-02 2.2E-12 100 101.10 100.10 10120.1 1.0E-04 2.0E-12 300 301.10 300.10 90360.1 1.1E-05 2.0E-12 For distribution curves: max kk+2 F = k K LW(D)+ (L+W)(D)k+1 + (D) k k+1 k+2 0.001 where: F = events per year L = length of repository (km) K = proportionality constant (from regression equation) W = width of the repository (km) k = power of the distribution (from regression equation) D = diameter of crater (km) For Wuschke et al.: F = 2.0 x 10-12 x D-2 x ( Ladjusted x Wadjusted) ANL-WIS-MD-000019 REV 01 IV-48 April 2004 Table IV-10c. Frequency (F) of Cratering Above Repository for TSPA-LA Siting Area TSPA-LA Siting Area L=5.4 W=2.6 V=15 km/s Crater Diameter D (km) K LWDk K (L+W)(Dk+1) k+1 D k+2 k+2 F(D) (sum of terms) kK(F(D)-F(D)max) UPPER CURVE FOR V=15 km/s K=7.0 E-10 k=-1.23 0.001 7.0E-10 -7.0E+04 -1.9E+02 6.1E-03 -7.0E+04 6.0E-05 0.002 7.0E-10 -3.0E+04 -1.6E+02 1.0E-02 -3.0E+04 2.5E-05 0.005 7.0E-10 -9.7E+03 -1.3E+02 2.1E-02 -9.8E+03 8.2E-06 0.007 7.0E-10 -6.4E+03 -1.2E+02 2.8E-02 -6.5E+03 5.3E-06 0.009 7.0E-10 -4.7E+03 -1.2E+02 3.4E-02 -4.8E+03 3.9E-06 0.01 7.0E-10 -4.1E+03 -1.1E+02 3.6E-02 -4.3E+03 3.4E-06 0.02 7.0E-10 -1.8E+03 -9.6E+01 6.2E-02 -1.9E+03 1.3E-06 0.03 7.0E-10 -1.1E+03 -8.8E+01 8.5E-02 -1.2E+03 7.3E-07 0.04 7.0E-10 -7.6E+02 -8.2E+01 1.1E-01 -8.4E+02 4.5E-07 0.05 7.0E-10 -5.8E+02 -7.8E+01 1.3E-01 -6.6E+02 2.9E-07 0.06 7.0E-10 -4.6E+02 -7.5E+01 1.5E-01 -5.4E+02 1.9E-07 0.07 7.0E-10 -3.8E+02 -7.3E+01 1.6E-01 -4.5E+02 1.2E-07 0.08 7.0E-10 -3.2E+02 -7.1E+01 1.8E-01 -3.9E+02 7.0E-08 0.1 7.0E-10 -2.5E+02 -6.7E+01 2.2E-01 -3.1E+02 0.0E+00 LOWER CURVE FOR V=15 km/s K=7.0 E-14 k=-1.14 0.09 7.0E-14 -2.5E+02 -8.9E+01 1.5E-01 -3.4E+02 3.7E-11 0.1 7.0E-14 -2.2E+02 -8.8E+01 1.6E-01 -3.1E+02 3.5E-11 0.2 7.0E-14 -9.9E+01 -8.0E+01 2.9E-01 -1.8E+02 2.4E-11 0.3 7.0E-14 -6.2E+01 -7.5E+01 4.1E-01 -1.4E+02 2.1E-11 0.4 7.0E-14 -4.5E+01 -7.2E+01 5.3E-01 -1.2E+02 1.9E-11 0.5 7.0E-14 -3.5E+01 -7.0E+01 6.4E-01 -1.0E+02 1.8E-11 0.6 7.0E-14 -2.8E+01 -6.8E+01 7.5E-01 -9.6E+01 1.8E-11 0.7 7.0E-14 -2.4E+01 -6.7E+01 8.6E-01 -8.9E+01 1.7E-11 0.8 7.0E-14 -2.0E+01 -6.5E+01 9.6E-01 -8.5E+01 1.7E-11 0.9 7.0E-14 -1.8E+01 -6.4E+01 1.1E+00 -8.1E+01 1.7E-11 1 7.0E-14 -1.6E+01 -6.3E+01 1.2E+00 -7.8E+01 1.6E-11 2 7.0E-14 -7.1E+00 -5.7E+01 2.1E+00 -6.2E+01 1.5E-11 3 7.0E-14 -4.5E+00 -5.4E+01 3.0E+00 -5.6E+01 1.5E-11 5 7.0E-14 -2.5E+00 -5.0E+01 4.6E+00 -4.8E+01 1.4E-11 10 7.0E-14 -1.1E+00 -4.6E+01 8.4E+00 -3.8E+01 1.3E-11 300 7.0E-14 -2.3E-02 -2.8E+01 1.6E+02 1.3E+02 0.0E+00 ANL-WIS-MD-000019 REV 01 IV-49 April 2004 Table IV-10c. Frequency (F) of Cratering Above Repository for TSPA-LA Siting Area (Continued) TSPA-LA Siting Area L=5.5 W=2.6 V=20 km/s Crater Diameter D (km) K LWDk k (L+W)(Dk+1) k+1 D k+2 k+2 F(D) (sum of terms) kK(F(D)-F(D)max) UPPER CURVE FOR V=20 km/s K= 3.0 E-09 k= -0.85 0.001 3.0E-09 -7.6E+03 2.2E+01 3.1E-04 -7.6E+03 1.9E-05 0.003 3.0E-09 -3.0E+03 2.6E+01 1.1E-03 -3.0E+03 6.8E-06 0.005 3.0E-09 -1.9E+03 2.8E+01 2.0E-03 -1.9E+03 4.1E-06 0.006 3.0E-09 -1.7E+03 2.9E+01 2.5E-03 -1.6E+03 3.4E-06 0.008 3.0E-09 -1.3E+03 3.0E+01 3.4E-03 -1.3E+03 2.5E-06 0.01 3.0E-09 -1.1E+03 3.1E+01 4.4E-03 -1.0E+03 1.9E-06 0.02 3.0E-09 -5.9E+02 3.4E+01 9.8E-03 -5.6E+02 6.9E-07 0.04 3.0E-09 -3.3E+02 3.8E+01 2.2E-02 -2.9E+02 0.0E+00 LOWER CURVE FOR V=20 km/s K=5.0 E-14 k=-0.85 0.03 5.0E-14 -4.2E+02 3.7E+01 1.6E-02 -3.8E+02 4.8E-11 0.04 5.0E-14 -3.3E+02 3.8E+01 2.2E-02 -2.9E+02 4.4E-11 0.05 5.0E-14 -2.7E+02 3.9E+01 2.8E-02 -2.3E+02 4.2E-11 0.06 5.0E-14 -2.3E+02 4.0E+01 3.5E-02 -1.9E+02 4.0E-11 0.07 5.0E-14 -2.0E+02 4.1E+01 4.1E-02 -1.6E+02 3.9E-11 0.08 5.0E-14 -1.8E+02 4.2E+01 4.8E-02 -1.4E+02 3.8E-11 0.09 5.0E-14 -1.6E+02 4.3E+01 5.5E-02 -1.2E+02 3.7E-11 0.1 5.0E-14 -1.5E+02 4.4E+01 6.2E-02 -1.1E+02 3.6E-11 0.2 5.0E-14 -8.3E+01 4.8E+01 1.4E-01 -3.5E+01 3.3E-11 0.3 5.0E-14 -5.9E+01 5.1E+01 2.2E-01 -7.4E+00 3.2E-11 0.4 5.0E-14 -4.6E+01 5.4E+01 3.0E-01 7.7E+00 3.2E-11 0.5 5.0E-14 -3.8E+01 5.5E+01 3.9E-01 1.8E+01 3.1E-11 0.6 5.0E-14 -3.3E+01 5.7E+01 4.9E-01 2.5E+01 3.1E-11 0.7 5.0E-14 -2.9E+01 5.8E+01 5.8E-01 3.0E+01 3.1E-11 0.8 5.0E-14 -2.6E+01 5.9E+01 6.7E-01 3.4E+01 3.0E-11 0.9 5.0E-14 -2.3E+01 6.0E+01 7.7E-01 3.8E+01 3.0E-11 1 5.0E-14 -2.1E+01 6.1E+01 8.7E-01 4.1E+01 3.0E-11 2 5.0E-14 -1.2E+01 6.8E+01 1.9E+00 5.8E+01 2.9E-11 3 5.0E-14 -8.3E+00 7.2E+01 3.1E+00 6.7E+01 2.9E-11 5 5.0E-14 -5.3E+00 7.8E+01 5.5E+00 7.8E+01 2.9E-11 10 5.0E-14 -3.0E+00 8.6E+01 1.2E+01 9.5E+01 2.8E-11 300 5.0E-14 -1.6E-01 1.4E+02 6.0E+02 7.5E+02 0.0E+00 ANL-WIS-MD-000019 REV 01 IV-50 April 2004 Table III-10c. Frequency (F) of Cratering Above Repository for TSPA-LA Siting Area (Continued) TSPA-LA Siting Area L=5.5 W=2.6 V=20 km/s Crater Diameter D (km) K LWDk k (L+W)(Dk+1) k+1 D k+2 k+2 F(D) (sum of terms) kK(F(D)-F(D)max) GRIEVE DISTRIBUTION K=1.20 E-12 k=-1.80 0.001 1.20E-12 -2.0E+06 -2.5E+03 1.3E+00 -2.0E+06 4.2E-06 0.01 1.20E-12 -3.1E+04 -4.0E+02 2.0E+00 -3.1E+04 6.8E-08 0.03 1.20E-12 -4.3E+03 -1.7E+02 2.5E+00 -4.5E+03 9.7E-09 0.04 1.20E-12 -2.6E+03 -1.3E+02 2.6E+00 -2.7E+03 5.8E-09 0.08 1.20E-12 -7.4E+02 -7.5E+01 3.0E+00 -8.1E+02 1.8E-09 0.1 1.20E-12 -4.9E+02 -6.3E+01 3.2E+00 -5.5E+02 1.2E-09 0.3 1.20E-12 -6.8E+01 -2.6E+01 3.9E+00 -9.0E+01 2.3E-10 0.7 1.20E-12 -1.5E+01 -1.3E+01 4.7E+00 -2.3E+01 8.4E-11 1 1.20E-12 -7.8E+00 -1.0E+01 5.0E+00 -1.3E+01 6.1E-11 10 1.20E-12 -1.2E-01 -1.6E+00 7.9E+00 6.2E+00 2.0E-11 100 1.20E-12 -2.0E-03 -2.5E-01 1.3E+01 1.2E+01 7.0E-12 300 1.20E-12 -2.7E-04 -1.0E-01 1.6E+01 1.6E+01 0.0E+00 WUSCHKE ET AL. DISTRIBUTION Crater Diameter (km) Adjusted L (km) Adjusted W (km) Adjusted Area (km2) D-2 F 0.001 5.40 2.60 14.0 1.0E+06 2.8E-05 0.01 5.41 2.61 14.1 1.0E+04 2.8E-07 0.03 5.43 2.63 14.3 1.1E+03 3.2E-08 0.04 5.44 2.64 14.4 6.3E+02 1.8E-08 0.08 5.48 2.68 14.7 1.6E+02 4.6E-09 0.1 5.50 2.70 14.9 1.0E+02 3.0E-09 0.3 5.70 2.90 16.5 1.1E+01 3.7E-10 0.7 6.10 3.30 20.1 2.0E+00 8.2E-11 1 6.40 3.60 23.0 1.0E+00 4.6E-11 10 15.40 12.60 194.0 1.0E-02 3.9E-12 100 105.40 102.60 10814.0 1.0E-04 2.2E-12 300 305.40 302.60 92414.0 1.1E-05 2.1E-12 For distribution curves: max kk+2 F = k K LW(D)+ (L+W)(D)k+1 + (D) k k+1 k+2 0.001 where: F = events per year L = length of repository (km) K = proportionality constant (from regression equation) W = width of the repository (km) k = power of the distribution (from regression equation) D = diameter of crater (km) For Wuschke et al.: F = 2.0 x 10-12 x D-2 x ( Ladjusted x Wadjusted) ANL-WIS-MD-000019 REV 01 IV-51 April 2004 Table IV-10d. Frequency (F) of Cratering Above Repository for TSPA-SR Design TSPA-SR Repository L=8.6 W=1.3 V=15 km/s Crater Diameter D (km)) K LWDk k (L+W)(Dk+1) k+1 D k+2 k+2 F(D) (sum of terms) kK(F(D)-F(D)max) UPPER CURVE FOR V=15 km/s K=7.0 E-10 k=-1.23 0.001 7.0E-10 -4.3E+04 -2.1E+02 6.1E-03 -4.4E+04 3.7E-05 0.002 7.0E-10 -1.9E+04 -1.8E+02 1.0E-02 -1.9E+04 1.6E-05 0.005 7.0E-10 -6.0E+03 -1.4E+02 2.1E-02 -6.2E+03 5.1E-06 0.007 7.0E-10 -4.0E+03 -1.3E+02 2.8E-02 -4.1E+03 3.3E-06 0.009 7.0E-10 -2.9E+03 -1.3E+02 3.4E-02 -3.1E+03 2.4E-06 0.01 7.0E-10 -2.6E+03 -1.2E+02 3.6E-02 -2.7E+03 2.1E-06 0.02 7.0E-10 -1.1E+03 -1.1E+02 6.2E-02 -1.2E+03 8.4E-07 0.03 7.0E-10 -6.7E+02 -9.7E+01 8.5E-02 -7.7E+02 4.6E-07 0.04 7.0E-10 -4.7E+02 -9.1E+01 1.1E-01 -5.6E+02 2.9E-07 0.05 7.0E-10 -3.6E+02 -8.6E+01 1.3E-01 -4.4E+02 1.9E-07 0.06 7.0E-10 -2.9E+02 -8.3E+01 1.5E-01 -3.7E+02 1.2E-07 0.07 7.0E-10 -2.4E+02 -8.0E+01 1.6E-01 -3.2E+02 7.7E-08 0.08 7.0E-10 -2.0E+02 -7.8E+01 1.8E-01 -2.8E+02 4.5E-08 0.1 7.0E-10 -1.5E+02 -7.4E+01 2.2E-01 -2.3E+02 0.0E+00 LOWER CURVE FOR V=15 km/s K=7.0 E-14 k=-1.14 0.09 7.0E-14 -1.5E+02 -9.8E+01 1.5E-01 -2.5E+02 3.0E-11 0.1 7.0E-14 -1.4E+02 -9.7E+01 1.6E-01 -2.3E+02 2.9E-11 0.2 7.0E-14 -6.2E+01 -8.8E+01 2.9E-01 -1.5E+02 2.2E-11 0.3 7.0E-14 -3.9E+01 -8.3E+01 4.1E-01 -1.2E+02 2.0E-11 0.4 7.0E-14 -2.8E+01 -7.9E+01 5.3E-01 -1.1E+02 1.8E-11 0.5 7.0E-14 -2.2E+01 -7.7E+01 6.4E-01 -9.8E+01 1.8E-11 0.6 7.0E-14 -1.8E+01 -7.5E+01 7.5E-01 -9.2E+01 1.7E-11 0.7 7.0E-14 -1.5E+01 -7.3E+01 8.6E-01 -8.7E+01 1.7E-11 0.8 7.0E-14 -1.3E+01 -7.2E+01 9.6E-01 -8.4E+01 1.7E-11 0.9 7.0E-14 -1.1E+01 -7.1E+01 1.1E+00 -8.1E+01 1.6E-11 1 7.0E-14 -9.8E+00 -7.0E+01 1.2E+00 -7.8E+01 1.6E-11 2 7.0E-14 -4.4E+00 -6.3E+01 2.1E+00 -6.5E+01 1.5E-11 3 7.0E-14 -2.8E+00 -6.0E+01 3.0E+00 -5.9E+01 1.5E-11 5 7.0E-14 -1.6E+00 -5.5E+01 4.6E+00 -5.2E+01 1.4E-11 10 7.0E-14 -7.1E-01 -5.0E+01 8.4E+00 -4.3E+01 1.3E-11 300 7.0E-14 -1.5E-02 -3.1E+01 1.6E+02 1.2E+02 0.0E+00 ANL-WIS-MD-000019 REV 01 IV-52 April 2004 Table IV-10d. Frequency (F) of Cratering Above Repository for TSPA-SR Design (Continued) TSPA-SR Repository L=8.6 W=1.3 V=20 km/s Crater Diameter D (km) K LWDk k (L+W)(Dk+1) k+1 D k+2 k+2 F(D) (sum of terms) kK(F(D)-F(D)max) UPPER CURVE FOR V=20 km/s K=3.0 E-09 k=-0.85 0.001 3.0E-09 -4.7E+03 2.4E+01 3.1E-04 -4.7E+03 1.2E-05 0.003 3.0E-09 -1.9E+03 2.9E+01 1.1E-03 -1.8E+03 4.3E-06 0.005 3.0E-09 -1.2E+03 3.1E+01 2.0E-03 -1.2E+03 2.6E-06 0.006 3.0E-09 -1.0E+03 3.2E+01 2.5E-03 -1.0E+03 2.1E-06 0.008 3.0E-09 -8.0E+02 3.3E+01 3.4E-03 -7.7E+02 1.6E-06 0.01 3.0E-09 -6.7E+02 3.4E+01 4.4E-03 -6.3E+02 1.2E-06 0.02 3.0E-09 -3.7E+02 3.8E+01 9.8E-03 -3.3E+02 4.3E-07 0.04 3.0E-09 -2.0E+02 4.2E+01 2.2E-02 -1.6E+02 0.0E+00 LOWER CURVE FOR V=20 km/s K=5.0 E-14 k=-0.85 0.03 5.0E-14 -2.6E+02 4.0E+01 1.6E-02 -2.2E+02 4.2E-11 0.04 5.0E-14 -2.0E+02 4.2E+01 2.2E-02 -1.6E+02 3.9E-11 0.05 5.0E-14 -1.7E+02 4.3E+01 2.8E-02 -1.3E+02 3.8E-11 0.06 5.0E-14 -1.4E+02 4.5E+01 3.5E-02 -1.0E+02 3.7E-11 0.07 5.0E-14 -1.3E+02 4.6E+01 4.1E-02 -8.1E+01 3.6E-11 0.08 5.0E-14 -1.1E+02 4.6E+01 4.8E-02 -6.7E+01 3.5E-11 0.09 5.0E-14 -1.0E+02 4.7E+01 5.5E-02 -5.5E+01 3.5E-11 0.1 5.0E-14 -9.3E+01 4.8E+01 6.2E-02 -4.5E+01 3.4E-11 0.2 5.0E-14 -5.2E+01 5.3E+01 1.4E-01 1.6E+00 3.2E-11 0.3 5.0E-14 -3.7E+01 5.6E+01 2.2E-01 2.0E+01 3.2E-11 0.4 5.0E-14 -2.9E+01 5.9E+01 3.0E-01 3.1E+01 3.1E-11 0.5 5.0E-14 -2.4E+01 6.1E+01 3.9E-01 3.8E+01 3.1E-11 0.6 5.0E-14 -2.0E+01 6.2E+01 4.9E-01 4.3E+01 3.1E-11 0.7 5.0E-14 -1.8E+01 6.4E+01 5.8E-01 4.7E+01 3.0E-11 0.8 5.0E-14 -1.6E+01 6.5E+01 6.7E-01 5.0E+01 3.0E-11 0.9 5.0E-14 -1.4E+01 6.6E+01 7.7E-01 5.3E+01 3.0E-11 1 5.0E-14 -1.3E+01 6.7E+01 8.7E-01 5.5E+01 3.0E-11 2 5.0E-14 -7.3E+00 7.5E+01 1.9E+00 6.9E+01 2.9E-11 3 5.0E-14 -5.1E+00 7.9E+01 3.1E+00 7.7E+01 2.9E-11 5 5.0E-14 -3.3E+00 8.5E+01 5.5E+00 8.8E+01 2.9E-11 10 5.0E-14 -1.8E+00 9.4E+01 1.2E+01 1.0E+02 2.8E-11 300 5.0E-14 -1.0E-01 1.6E+02 6.0E+02 7.6E+02 0.0E+00 ANL-WIS-MD-000019 REV 01 IV-53 April 2004 Table IV-10d. Frequency (F) of Cratering Above Repository for TSPA-SR Design (Continued) TSPA-SR Repository L=8.6 W=1.3 V=20 km/s Crater Diameter D (km) K LWDk k (L+W)(Dk+1) k+1 D k+2 k+2 F(D) (sum of terms) kK(F(D)-F(D)max) GRIEVE DISTRIBUTION K=1.20 E-12 k=-1.8 0.001 1.20E-12 -1.6E+06 -3.1E+03 1.3E+00 -1.6E+06 3.4E-06 0.01 1.20E-12 -2.5E+04 -4.9E+02 2.0E+00 -2.5E+04 5.5E-08 0.03 1.20E-12 -3.4E+03 -2.0E+02 2.5E+00 -3.6E+03 7.9E-09 0.04 1.20E-12 -2.0E+03 -1.6E+02 2.6E+00 -2.2E+03 4.8E-09 0.08 1.20E-12 -5.9E+02 -9.3E+01 3.0E+00 -6.8E+02 1.5E-09 0.1 1.20E-12 -3.9E+02 -7.8E+01 3.2E+00 -4.7E+02 1.0E-09 0.3 1.20E-12 -5.4E+01 -3.2E+01 3.9E+00 -8.3E+01 2.1E-10 0.7 1.20E-12 -1.2E+01 -1.6E+01 4.7E+00 -2.4E+01 8.5E-11 1 1.20E-12 -6.2E+00 -1.2E+01 5.0E+00 -1.4E+01 6.3E-11 10 1.20E-12 -9.8E-02 -2.0E+00 7.9E+00 5.9E+00 2.1E-11 100 1.20E-12 -1.6E-03 -3.1E-01 1.3E+01 1.2E+01 7.1E-12 300 1.20E-12 -2.2E-04 -1.3E-01 1.6E+01 1.6E+01 0.0E+00 WUSCHKE ET AL. DISTRIBUTION Crater Diameter D (km) Adjusted L (km) Adjusted W (km) Adjusted Area (km2) D-2 F 0.001 8.60 1.30 11.2 1.0E+06 2.2E-05 0.01 8.61 1.31 11.3 1.0E+04 2.3E-07 0.03 8.63 1.33 11.5 1.1E+03 2.6E-08 0.04 8.64 1.34 11.6 6.3E+02 1.4E-08 0.08 8.68 1.38 12.0 1.6E+02 3.7E-09 0.1 8.70 1.40 12.2 1.0E+02 2.4E-09 0.3 8.90 1.60 14.2 1.1E+01 3.2E-10 0.7 9.30 2.00 18.6 2.0E+00 7.6E-11 1 9.6 2.3 22.1 1.0E+00 4.4E-11 10 18.6 11.3 210.2 1.0E-02 4.2E-12 100 109 101 11001 1.0E-04 2.2E-12 300 309 301 92981 1.1E-05 2.1E-12 For distribution curves: max kk+2 F = k K LW(D)+ (L+W)(D)k+1 + (D) k k+1 k+2 0.001 where: F = events per year L = length of repository (km) K = proportionality constant (from regression equation) W = width of the repository (km) k = power of the distribution (from regression equation) D = diameter of crater (km) For Wuschke et al.: F = 2.0 x 10-12 x D-2 x ( Ladjusted x Wadjusted) ANL-WIS-MD-000019 REV 01 IV-54 April 2004 Table IV-11. Spreadsheet Example: Calculation of Distribution Curves for V = 15 km/s 8.6 1.3 ANL-WIS-MD-000019 REV 01 Repository L= W= From Regression Analysis Equation: K= '=Regression Analyses'!E20 k=='Regression Analyses'!E19 K Coefficients for Power Distribution - Upper Curve D(15) =E3 =G3 =C6+1 =C6+2 Sum of Terms F 0.001 =$B$6 0.002 =$B$6 0.005 =$B$6 0.007 =$B$6 0.009 =$B$6 0.01 =$B$6 IV-55 0.02 =$B$6 0.03 =$B$6 0.04 =$B$6 0.05 =$B$6 0.06 =$B$6 0.07 =$B$6 0.08 =$B$6 0.1 =$B$6 April 2004 =($C$1*$E$1*A8^$C$6)/$C$6 =($C$1+$E$1)*(A8^$D$6)/$D$6 =A8^$E$6/$E$6 =SUM(C8:E8) =$C$6*B8*(F8-$F$23) =($C$1*$E$1*A9^$C$6)/$C$6 =($C$1+$E$1)*(A9^$D$6)/$D$6 =A9^$E$6/$E$6 =SUM(C9:E9) =$C$6*B9*(F9-$F$23) =($C$1*$E$1*A10^$C$6)/$C$6 =($C$1+$E$1)*(A10^$D$6)/$D$6 =A10^$E$6/$E$6 =SUM(C10:E10) =$C$6*B10*(F10-$F$23) =($C$1*$E$1*A11^$C$6)/$C$6 =($C$1+$E$1)*(A11^$D$6)/$D$6 =A11^$E$6/$E$6 =SUM(C11:E11) =$C$6*B11*(F11-$F$23) =($C$1*$E$1*A12^$C$6)/$C$6 =($C$1+$E$1)*(A12^$D$6)/$D$6 =A12^$E$6/$E$6 =SUM(C12:E12) =$C$6*B12*(F12-$F$23) =($C$1*$E$1*A13^$C$6)/$C$6 =($C$1+$E$1)*(A13^$D$6)/$D$6 =A13^$E$6/$E$6 =SUM(C13:E13) =$C$6*B13*(F13-$F$23) =($C$1*$E$1*A14^$C$6)/$C$6 =($C$1+$E$1)*(A14^$D$6)/$D$6 =A14^$E$6/$E$6 =SUM(C14:E14) =$C$6*B14*(F14-$F$23) =($C$1*$E$1*A15^$C$6)/$C$6 =($C$1+$E$1)*(A15^$D$6)/$D$6 =A15^$E$6/$E$6 =SUM(C15:E15) =$C$6*B15*(F15-$F$23) =($C$1*$E$1*A16^$C$6)/$C$6 =($C$1+$E$1)*(A16^$D$6)/$D$6 =A16^$E$6/$E$6 =SUM(C16:E16) =$C$6*B16*(F16-$F$23) =($C$1*$E$1*A17^$C$6)/$C$6 =($C$1+$E$1)*(A17^$D$6)/$D$6 =A17^$E$6/$E$6 =SUM(C17:E17) =$C$6*B17*(F17-$F$23) =($C$1*$E$1*A18^$C$6)/$C$6 =($C$1+$E$1)*(A18^$D$6)/$D$6 =A18^$E$6/$E$6 =SUM(C18:E18) =$C$6*B18*(F18-$F$23) =($C$1*$E$1*A19^$C$6)/$C$6 =($C$1+$E$1)*(A19^$D$6)/$D$6 =A19^$E$6/$E$6 =SUM(C19:E19) =$C$6*B19*(F19-$F$23) =($C$1*$E$1*A20^$C$6)/$C$6 =($C$1+$E$1)*(A20^$D$6)/$D$6 =A20^$E$6/$E$6 =SUM(C20:E20) =$C$6*B20*(F20-$F$23) =($C$1*$E$1*A23^$C$6)/$C$6 =($C$1+$E$1)*(A23^$D$6)/$D$6 =A23^$E$6/$E$6 =SUM(C23:E23) =$C$6*B23*(F23-$F$23) Table IV-11. Spreadsheet Example: Calculation of Distribution Curves for V = 15 km/s (Continued) 1 2 3 5 10 300 ANL-WIS-MD-000019 REV 01 IV-56 April 2004 0.09 =$B$28 0.1 =$B$28 0.2 =$B$28 0.3 =$B$28 0.4 =$B$28 0.5 =$B$28 0.6 =$B$28 0.7 =$B$28 0.8 =$B$28 0.9 =$B$28 =$B$28 =$B$28 =$B$28 =$B$28 =$B$28 =$B$28 From Regression Analysis Equation: K= k=='Regression Analyses'!E44 ='Regression Analyses'!E45 K Coefficients for Power Distribution - Lower Curve D(15) =E26 =G26 =C28+1 =C28+2 Sum of Terms F =($C$1*$E$1*A30^$C$28)/$C$28 =($C$1+$E$1)*(A30^$D$28)/$D$28 =A30^$E$28/$E$28 =SUM(C30:E30) =$C$28*B30*(F30-$F$45) =($C$1*$E$1*A31^$C$28)/$C$28 =($C$1+$E$1)*(A31^$D$28)/$D$28 =A31^$E$28/$E$28 =SUM(C31:E31) =$C$28*B31*(F31-$F$45) =($C$1*$E$1*A32^$C$28)/$C$28 =($C$1+$E$1)*(A32^$D$28)/$D$28 =A32^$E$28/$E$28 =SUM(C32:E32) =$C$28*B32*(F32-$F$45) =($C$1*$E$1*A33^$C$28)/$C$28 =($C$1+$E$1)*(A33^$D$28)/$D$28 =A33^$E$28/$E$28 =SUM(C33:E33) =$C$28*B33*(F33-$F$45) =($C$1*$E$1*A34^$C$28)/$C$28 =($C$1+$E$1)*(A34^$D$28)/$D$28 =A34^$E$28/$E$28 =SUM(C34:E34) =$C$28*B34*(F34-$F$45) =($C$1*$E$1*A35^$C$28)/$C$28 =($C$1+$E$1)*(A35^$D$28)/$D$28 =A35^$E$28/$E$28 =SUM(C35:E35) =$C$28*B35*(F35-$F$45) =($C$1*$E$1*A36^$C$28)/$C$28 =($C$1+$E$1)*(A36^$D$28)/$D$28 =A36^$E$28/$E$28 =SUM(C36:E36) =$C$28*B36*(F36-$F$45) =($C$1*$E$1*A37^$C$28)/$C$28 =($C$1+$E$1)*(A37^$D$28)/$D$28 =A37^$E$28/$E$28 =SUM(C37:E37) =$C$28*B37*(F37-$F$45) =($C$1*$E$1*A38^$C$28)/$C$28 =($C$1+$E$1)*(A38^$D$28)/$D$28 =A38^$E$28/$E$28 =SUM(C38:E38) =$C$28*B38*(F38-$F$45) =($C$1*$E$1*A39^$C$28)/$C$28 =($C$1+$E$1)*(A39^$D$28)/$D$28 =A39^$E$28/$E$28 =SUM(C39:E39) =$C$28*B39*(F39-$F$45) =($C$1*$E$1*A40^$C$28)/$C$28 =($C$1+$E$1)*(A40^$D$28)/$D$28 =A40^$E$28/$E$28 =SUM(C40:E40) =$C$28*B40*(F40-$F$45) =($C$1*$E$1*A41^$C$28)/$C$28 =($C$1+$E$1)*(A41^$D$28)/$D$28 =A41^$E$28/$E$28 =SUM(C41:E41) =$C$28*B41*(F41-$F$45) =($C$1*$E$1*A42^$C$28)/$C$28 =($C$1+$E$1)*(A42^$D$28)/$D$28 =A42^$E$28/$E$28 =SUM(C42:E42) =$C$28*B42*(F42-$F$45) =($C$1*$E$1*A43^$C$28)/$C$28 =($C$1+$E$1)*(A43^$D$28)/$D$28 =A43^$E$28/$E$28 =SUM(C43:E43) =$C$28*B43*(F43-$F$45) =($C$1*$E$1*A44^$C$28)/$C$28 =($C$1+$E$1)*(A44^$D$28)/$D$28 =A44^$E$28/$E$28 =SUM(C44:E44) =$C$28*B44*(F44-$F$45) =($C$1*$E$1*A45^$C$28)/$C$28 =($C$1+$E$1)*(A45^$D$28)/$D$28 =A45^$E$28/$E$28 =SUM(C45:E45) =$C$28*B45*(F45-$F$45) 0.001 0.003 0.005 0.006 0.008 0.01 0.02 0.04 ANL-WIS-MD-000019 REV 01 IV-57 April 2004 Table IV-12. Spreadsheet Example: Calculation of Distribution Curves for V = 20 km/s 8.6 W= From Regression Analysis Equation: K= Repository L= 1.3 ='Regression Analyses'!P20 k=='Regression Analyses'!P19 D(20) K Coefficients for Power Distribution - Upper Curve =E3 =G3 =C6+1 =C6+2 Sum of Terms =$B$6 =($C$1*$E$1*A8^$C$6)/$C$6 =($C$1+$E$1)*(A8^$D$6)/$D$6 =A8^$E$6/$E$6 =SUM(C8:E8) =$C$6*B8*(F8-$F$15) =$B$6 =($C$1*$E$1*A9^$C$6)/$C$6 =($C$1+$E$1)*(A9^$D$6)/$D$6 =A9^$E$6/$E$6 =SUM(C9:E9) =$C$6*B9*(F9-$F$15) =$B$6 =($C$1*$E$1*A10^$C$6)/$C$6 =($C$1+$E$1)*(A10^$D$6)/$D$6 =A10^$E$6/$E$6 =SUM(C10:E10) =$C$6*B10*(F10-$F$15) =$B$6 =($C$1*$E$1*A11^$C$6)/$C$6 =($C$1+$E$1)*(A11^$D$6)/$D$6 =A11^$E$6/$E$6 =SUM(C11:E11) =$C$6*B11*(F11-$F$15) =$B$6 =($C$1*$E$1*A12^$C$6)/$C$6 =($C$1+$E$1)*(A12^$D$6)/$D$6 =A12^$E$6/$E$6 =SUM(C12:E12) =$C$6*B12*(F12-$F$15) =$B$6 =($C$1*$E$1*A13^$C$6)/$C$6 =($C$1+$E$1)*(A13^$D$6)/$D$6 =A13^$E$6/$E$6 =SUM(C13:E13) =$C$6*B13*(F13-$F$15) =$B$6 =($C$1*$E$1*A14^$C$6)/$C$6 =($C$1+$E$1)*(A14^$D$6)/$D$6 =A14^$E$6/$E$6 =SUM(C14:E14) =$C$6*B14*(F14-$F$15) =$B$6 =($C$1*$E$1*A15^$C$6)/$C$6 =($C$1+$E$1)*(A15^$D$6)/$D$6 =A15^$E$6/$E$6 =SUM(C15:E15) =$C$6*B15*(F15-$F$15) Table IV-12. Spreadsheet Example: Calculation of Distribution Curves for V = 20 km/s (Continued) 1 2 3 5 10 300 ANL-WIS-MD-000019 REV 01 IV-58 April 2004 0.03 =$B$21 = 0.04 =$B$21 = 0.05 =$B$21 = 0.06 =$B$21 = 0.07 =$B$21 = 0.08 =$B$21 = 0.09 =$B$21 = 0.1 =$B$21 = 0.2 =$B$21 = 0.3 =$B$21 = 0.4 =$B$21 = 0.5 =$B$21 = 0.6 =$B$21 = 0.7 =$B$21 = 0.8 =$B$21 = 0.9 =$B$21 = =$B$21 = =$B$21 = =$B$21 = =$B$21 = =$B$21 = =$B$21 =($C$1*$E$1*A44^$C$21)/$C$21 ='Regression Analyses'!P45 k=='Regression Analyses'!P44 From Regression Analysis Equation: K= D(20) K Coefficients for Power Distribution - Lower Curve =E18 =G18 =C21+1 =C21+2 Sum of Terms F ($C$1*$E$1*A23^$C$21)/$C$21 =($C$1+$E$1)*(A23^$D$21)/$D$21 =A23^$E$21/$E$21 =SUM(C23:E23) =$C$21*B23*(F23-$F$44) ($C$1*$E$1*A24^$C$21)/$C$21 =($C$1+$E$1)*(A24^$D$21)/$D$21 =A24^$E$21/$E$21 =SUM(C24:E24) =$C$21*B24*(F24-$F$44) ($C$1*$E$1*A25^$C$21)/$C$21 =($C$1+$E$1)*(A25^$D$21)/$D$21 =A25^$E$21/$E$21 =SUM(C25:E25) =$C$21*B25*(F25-$F$44) ($C$1*$E$1*A26^$C$21)/$C$21 =($C$1+$E$1)*(A26^$D$21)/$D$21 =A26^$E$21/$E$21 =SUM(C26:E26) =$C$21*B26*(F26-$F$44) ($C$1*$E$1*A27^$C$21)/$C$21 =($C$1+$E$1)*(A27^$D$21)/$D$21 =A27^$E$21/$E$21 =SUM(C27:E27) =$C$21*B27*(F27-$F$44) ($C$1*$E$1*A28^$C$21)/$C$21 =($C$1+$E$1)*(A28^$D$21)/$D$21 =A28^$E$21/$E$21 =SUM(C28:E28) =$C$21*B28*(F28-$F$44) ($C$1*$E$1*A29^$C$21)/$C$21 =($C$1+$E$1)*(A29^$D$21)/$D$21 =A29^$E$21/$E$21 =SUM(C29:E29) =$C$21*B29*(F29-$F$44) ($C$1*$E$1*A30^$C$21)/$C$21 =($C$1+$E$1)*(A30^$D$21)/$D$21 =A30^$E$21/$E$21 =SUM(C30:E30) =$C$21*B30*(F30-$F$44) ($C$1*$E$1*A31^$C$21)/$C$21 =($C$1+$E$1)*(A31^$D$21)/$D$21 =A31^$E$21/$E$21 =SUM(C31:E31) =$C$21*B31*(F31-$F$44) ($C$1*$E$1*A32^$C$21)/$C$21 =($C$1+$E$1)*(A32^$D$21)/$D$21 =A32^$E$21/$E$21 =SUM(C32:E32) =$C$21*B32*(F32-$F$44) ($C$1*$E$1*A33^$C$21)/$C$21 =($C$1+$E$1)*(A33^$D$21)/$D$21 =A33^$E$21/$E$21 =SUM(C33:E33) =$C$21*B33*(F33-$F$44) ($C$1*$E$1*A34^$C$21)/$C$21 =($C$1+$E$1)*(A34^$D$21)/$D$21 =A34^$E$21/$E$21 =SUM(C34:E34) =$C$21*B34*(F34-$F$44) ($C$1*$E$1*A35^$C$21)/$C$21 =($C$1+$E$1)*(A35^$D$21)/$D$21 =A35^$E$21/$E$21 =SUM(C35:E35) =$C$21*B35*(F35-$F$44) ($C$1*$E$1*A36^$C$21)/$C$21 =($C$1+$E$1)*(A36^$D$21)/$D$21 =A36^$E$21/$E$21 =SUM(C36:E36) =$C$21*B36*(F36-$F$44) ($C$1*$E$1*A37^$C$21)/$C$21 =($C$1+$E$1)*(A37^$D$21)/$D$21 =A37^$E$21/$E$21 =SUM(C37:E37) =$C$21*B37*(F37-$F$44) ($C$1*$E$1*A38^$C$21)/$C$21 =($C$1+$E$1)*(A38^$D$21)/$D$21 =A38^$E$21/$E$21 =SUM(C38:E38) =$C$21*B38*(F38-$F$44) ($C$1*$E$1*A39^$C$21)/$C$21 =($C$1+$E$1)*(A39^$D$21)/$D$21 =A39^$E$21/$E$21 =SUM(C39:E39) =$C$21*B39*(F39-$F$44) ($C$1*$E$1*A40^$C$21)/$C$21 =($C$1+$E$1)*(A40^$D$21)/$D$21 =A40^$E$21/$E$21 =SUM(C40:E40) =$C$21*B40*(F40-$F$44) ($C$1*$E$1*A41^$C$21)/$C$21 =($C$1+$E$1)*(A41^$D$21)/$D$21 =A41^$E$21/$E$21 =SUM(C41:E41) =$C$21*B41*(F41-$F$44) ($C$1*$E$1*A42^$C$21)/$C$21 =($C$1+$E$1)*(A42^$D$21)/$D$21 =A42^$E$21/$E$21 =SUM(C42:E42) =$C$21*B42*(F42-$F$44) ($C$1*$E$1*A43^$C$21)/$C$21 =($C$1+$E$1)*(A43^$D$21)/$D$21 =A43^$E$21/$E$21 =SUM(C43:E43) =$C$21*B43*(F43-$F$44) =($C$1+$E$1)*(A44^$D$21)/$D$21 =A44^$E$21/$E$21 =SUM(C44:E44) =$C$21*B44*(F44-$F$44) Table IV-13. Spreadsheet Example: Formulas for Calculating Grieve Distribution Repository L= ANL-WIS-MD-000019 REV 01 8.6 W= Grieve K k Coefficient for Power Distribution 1.3 1.2 E--12 -1.8 =C4+1 =C4+2 0.001 =$B$4 0.01 =$B$4 IV-59 0.03 =$B$4 0.04 =$B$4 0.08 =$B$4 0.1 =$B$4 0.3 =$B$4 0.7 =$B$4 1 =$B$4 April 2004 10 =$B$4 100 =$B$4 300 =$B$4 =($C$1*$E$1*A6^$C$4)/$C$4 =($C$1+$E$1)*(A6^$D$4)/$D$4 =A6^$E$4/$E$4 =SUM(C6:E6) =$C$4*B6*(F6-$F$17) =($C$1*$E$1*A7^$C$4)/$C$4 =($C$1+$E$1)*(A7^$D$4)/$D$4 =A7^$E$4/$E$4 =SUM(C7:E7) =$C$4*B7*(F7-$F$17) =($C$1*$E$1*A8^$C$4)/$C$4 =($C$1+$E$1)*(A8^$D$4)/$D$4 =A8^$E$4/$E$4 =SUM(C8:E8) =$C$4*B8*(F8-$F$17) =($C$1*$E$1*A9^$C$4)/$C$4 =($C$1+$E$1)*(A9^$D$4)/$D$4 =A9^$E$4/$E$4 =SUM(C9:E9) =$C$4*B9*(F9-$F$17) =($C$1*$E$1*A10^$C$4)/$C$4 =($C$1+$E$1)*(A10^$D$4)/$D$4 =A10^$E$4/$E$4 =SUM(C10:E10) =$C$4*B10*(F10-$F$17) =($C$1*$E$1*A11^$C$4)/$C$4 =($C$1+$E$1)*(A11^$D$4)/$D$4 =A11^$E$4/$E$4 =SUM(C11:E11) =$C$4*B11*(F11-$F$17) =($C$1*$E$1*A12^$C$4)/$C$4 =($C$1+$E$1)*(A12^$D$4)/$D$4 =A12^$E$4/$E$4 =SUM(C12:E12) =$C$4*B12*(F12-$F$17) =($C$1*$E$1*A13^$C$4)/$C$4 =($C$1+$E$1)*(A13^$D$4)/$D$4 =A13^$E$4/$E$4 =SUM(C13:E13) =$C$4*B13*(F13-$F$17) =($C$1*$E$1*A14^$C$4)/$C$4 =($C$1+$E$1)*(A14^$D$4)/$D$4 =A14^$E$4/$E$4 =SUM(C14:E14) =$C$4*B14*(F14-$F$17) =($C$1*$E$1*A15^$C$4)/$C$4 =($C$1+$E$1)*(A15^$D$4)/$D$4 =A15^$E$4/$E$4 =SUM(C15:E15) =$C$4*B15*(F15-$F$17) =($C$1*$E$1*A16^$C$4)/$C$4 =($C$1+$E$1)*(A16^$D$4)/$D$4 =A16^$E$4/$E$4 =SUM(C16:E16) =$C$4*B16*(F16-$F$17) =($C$1*$E$1*A17^$C$4)/$C$4 =($C$1+$E$1)*(A17^$D$4)/$D$4 =A17^$E$4/$E$4 =SUM(C17:E17) =$C$4*B17*(F17-$F$17) ANL-WIS-MD-000019 REV 01 IV-60 April 2004 Table IV-14. Spreadsheet Example: Formulas for Calculating Wuschke et al. Distribution Frequency Calculation and Area Adjustment for Distribution per Wuschke et al. 1995 Repository L= 8.3 W= 1.3 Crater Diameter (km) Adjusted L (km) Adjusted W (km) Adjusted Area (km2) D-2 Frequency per year 0.001 =$C$3+A6 =$E$3+A6 =B6*C6 =A6^-2 =D6*E6*0.000000000002 =$C$3+A7 =$E$3+A7 =B7*C7 =A7^-2 =D7*E7*0.000000000002 0.01 =$C$3+A8 =$E$3+A8 =B8*C8 =A8^-2 =D8*E8*0.000000000002 0.03 =$C$3+A9 =$E$3+A9 =B9*C9 =A9^-2 =D9*E9*0.000000000002 0.04 =$C$3+A10 =$E$3+A10 =B10*C10 =A10^-2 =D10*E10*0.000000000002 0.08 =$C$3+A11 =$E$3+A11 =B11*C11 =A11^-2 =D11*E11*0.000000000002 0.1 =$C$3+A12 =$E$3+A12 =B12*C12 =A12^-2 =D12*E12*0.000000000002 0.3 =$C$3+A13 =$E$3+A13 =B13*C13 =A13^-2 =D13*E13*0.000000000002 =$C$3+A14 =$E$3+A14 =B14*C14 =A14^-2 =D14*E14*0.000000000002 10 0.7 =$C$3+A15 =$E$3+A15 =B15*C15 =A15^-2 =D15*E15*0.000000000002 100 =$C$3+A16 =$E$3+A16 =B16*C16 =A16^-2 =D16*E16*0.000000000002 300 =$C$3+A17 =$E$3+A17 =B17*C17 =A17^-2 =D17*E17*0.000000000002 2.4 UNCERTAINTY CONSIDERATIONS Uncertainties for the meteorite impact analysis include both epistemic and aleatory uncertainties. Aleatory uncertainties in the physical properties of observed objects (e.g., density, velocities, diameters, angle of entry) are inherent in assuming such values for calculating meteor radius. Epistemic uncertainties are reflected in the distributions used for the mass flux and for the percentage of types of meteors that occur within the entire population of possible earth interceptors. This is due to observations of only a limited number of objects over a very short period compared to that involved in determining crater rate distributions. The evaluation approach used to define the probability distribution can include consideration of probability of impact of known objects, probabilities based on empirical cratering observations from the lunar and earth’s surface, or determination of probabilities based on meteor flux to the earth’s atmosphere. The first option, impact of known objects, is only of limited use because space surveys are currently incomplete, and there are large uncertainties that influence the probability calculations. However, it does serve as a corroborative checkpoint for comparison for any other derived values. For the second option, empirical crater observations, uncertainties stem from uncertainty in the age of observed craters, uncertainties regarding overprinting from multiple impacts in a given area, and extrapolations required to account for differences in atmospheric and gravitational effects. In the case of earth cratering studies, the limitations also include the destruction of small diameter craters through time and/or limitations in identification of such features. For the last option, a crater distribution based on meteor flux, the analysis encounters uncertainties in accounting for multiple factors. These factors include the distribution of the mass and diameter of the meteoroids, the distribution in composition of meteoroids, the velocity of the meteoroids, their entry angle into the earth’s atmosphere, and effects encountered by the meteor during passage through Earth’s atmosphere (ablation and fragmentation). Each of the factors (mass or size, material, velocity, angle, and atmospheric effects) determines the kinetic energy with which the meteorite impacts the earth, and thereby influences the resulting crater diameter and depth. The curve derived from Grieve in Figure IV-3 is based on extrapolation of observable earth cratering data, but its limitation is for crater diameters larger than 10 km. For this analysis, however, the slope of the Grieve distribution was assumed constant even for the smaller crater diameters. The extrapolation of the distribution from Grieve (1998 [DIRS 163385]) for very small crater diameters likely overestimates the number of small-diameter craters, and is therefore conservative (i.e., the number of small cratering events may be overestimated in the calculation) due to the extrapolation of the curve. The number of observed small diameter craters as noted by Grieve’s is substantially less than that projected by the extrapolated distribution, and would in fact be the true lower bound. The degree of conservatism, however, cannot be quantified because the number of observed small diameter craters is skewed because it does not account for atmospheric effects on small meteors, increased obscuration of smaller diameter craters by weathering and burial, and the implicit difficulty in identifying small diameter craters. The crater diameter distribution observed by Grieve and based on large crater diameters, however, at least includes the effects of ablation and fragmentation as reflected for large diameter craters. The curve from Wuschke et al. (1995 [DIRS 129326]) is based on a subset of the Grieve information and, if comparable to the information used by Hughes (1998 [DIRS 162562]) may ANL-WIS-MD-000019 REV 01 IV-61 April 2004 only be valid down to diameters of 1 km. The data derived from Wuschke et al. (1995 [DIRS 129326]) may represent a more realistic distribution of actual size and has been applied to a hypothetical Canadian repository. Furthermore, the curves derived from the cumulative flux data in Figure IV-3, and based on the modeling results from Hills and Goda (1993, Figures 16 and 17 [DIRS 135281]), are dependent on the assumptions regarding composition, assumed densities, and the relative composition of the cumulative flux. The cumulative flux curves overstate the frequency of impact resulting in a given crater diameter if the relative percent of iron meteorites is lower and/or the percent of carbonaceous meteorites is greater than that assumed. Also, these curves likely overstate the frequency because it is assumed that the entire flux enters earth’s atmosphere at angles that result in the least atmospheric dissipation. With regard to the flux of meteoroids to earth, the reported values of the cumulative number of events for a meteoroid of a given diameter or larger is provided in Figure II-1 of Attachment II of this analysis report and spans approximately two orders of magnitude, with the range in values decreasing slightly for meteor diameters on the order of 1,000 meters or greater. For the analysis, a conservative set of data for the range of interest was selected. Use of a different data set would likely result in a decreased rate of cratering of a given diameter, although the relationship is not linear due to atmospheric shield effects. There is a large uncertainty associated with the distribution of meteoroids based on composition as shown in Table II-13 of Attachment II. Selection of a distribution that prefers a cometary composition would tend to decrease the probability of given crater diameter due to the greater effect of atmospheric shielding effects on cometary and soft stone meteoroids for a given diameter. Similarly, decreased percentage of iron meteorids (Table II-14 of Attachment II) would also tend to decrease the cratering rate for a given diameter because iron meteors are stronger and more dense that stony meteors of the same diameter and result in larger crater diameters. A reasonable, but conservative, value of 5 percent iron meteors was selected to minimize the effects of uncertainty in the percent irons. The selected value is thought conservative, because as shown in Table II-14 of Attachment II of this analysis report, the average of the reported values was 5 percent, but only 4 of 13 of the reported values exceeded 5 percent. These higher values are likely biased because they are based on meteorite finds and iron-type meteorites are more likely to be found. One value (17.8 percent) drives the average. Excluding the extreme value of 17.8 results in an average value of 3.9 percent. For the stony/cometary percentages, an equal distribution was used for larger diameters, and a decreased percentage of stony material was used for the small masses and diameters. Selection of a more equal distribution would increase the crater diameter rates, although the increase would not be linear due to the continued effects of atmospheric shielding effects (albeit shifted based on initial diameter). However, the use of the more conservative value of 5 percent for iron meteors may also compensate in part for a preferred cometary composition for smaller meteoroids. There is also uncertainty associated with meteoroid densities. In reality, meteoroid densities likely show some type of modal distributions based on parent bodies and origin, and vary according the range of compositions considered. The range of values from the literature search is provided in Table II-15 of Attachment II of this analysis report. To simplify the calculation, the compositions were binned into three types (metallic, stony, and carbonaceous) and ANL-WIS-MD-000019 REV 01 IV-62 April 2004 reasonable but conservative values for density were assigned for each type as previously. The calculation is structured in such a way that increases or decreases in assumed density would directly affect the calculated radius of a meteoroid of a given mass, with an increase in density leading to decreased equivalent meteoroid radius. A decrease in the density by a factor of two would increase the calculated meteoroid radius by a factor of only about 1.3. A decrease in initial meteoroid radius generally would result in a decreased resulting crater diameter. Additionally, there is little information regarding the distribution of initial velocities or entry angle of meteoroids impacting the earth’s surface, although upper and lower bounds for the distributions could be established. These uncertainties are addressed, by assuming conservative values for both factors, as described for Assumption 5.4. Regardless of the uncertainty in physical property distributions, the net effects of uncertainty are partially addressed by comparing the cratering distribution derived from meteoroid influx, to those derived based on lunar cratering rates and on observed earth cratering rates. The lunar- and earth-based cratering rates respectively represent a true upper bound, and a reasonable lower bound on cratering rates. These distributions of observed features reflect the net effect of all uncertainties in physical property distributions on the resulting crater diameter distributions. However, for crater diameters less than about 10 km, there is a high degree of uncertainty with regard to the actual cratering rate due to the inability to detect smaller scale features, and due to the destruction of smaller scale crater diameters by natural processes acting over prolonged time periods. 3. IMPLICATIONS FOR FEP SCREENING AND CONCLUSIONS The probability of the occurrence of crater diameters of interest (i.e., the diameters that define whether the repository is affected by direct exhumation, fracturing to repository depth, or fracturing of other overlying units of interest) is compared to the FEP screening threshold diameter of one chance in 10,000 of occurring in 10,000 years (or an annualized occurrence of 10-8). If the probability of occurrence is less than this threshold, the effect can be excluded from further consideration in TSPA-LA. If not, then the effect is examined for “significance.” If it can be demonstrated that the omission of the effect would not significantly change radionuclide exposure or release to the accessible environment, then the effect can be excluded from further consideration in TSPA-LA. As shown on Figure IV-7, the probability of the formation of crater diameters above or near the repository that is sufficient to result in exhumation and/or fracturing to the depth of the repository falls below the FEP screening probability threshold. Likewise, exhumation and/or fracturing to the top of the Paintbrush hydrologic unit above or near the repository is also excluded because the occurrence of such craters falls below the FEP screening probability threshold. This holds true for each of the cratering distributions considered for all but the easternmost portion of the repository. Figure IV-8 addresses the potential for cratering in the Paintbrush hydrologic unit outcrop area, which is discussed separately. Figure IV-7 indicates that at an annualized probability of 10-8, the corresponding crater diameter resulting from impact of the largest meteor fragment is likely to range from 20 to 80 m. The 80m diameter represents the minimum diameter needed to fracture to the depth of the PTn unit in ANL-WIS-MD-000019 REV 01 IV-63 April 2004 the easternmost portion of the repository, where the unit is shallowest, and is taken from the V=15 km/sec distribution curve. The other distribution curves indicate lesser crater diameters, suggesting that meteorite impact is of low consequence. An 80-m crater diameter corresponds to a maximum total surface area of about 0.005 km2, or about 0.04 percent of the repository surface area of 14 km2 for any crater resulting from the largest fragment (based on Hills and Goda 1993, Figure 17 [DIRS 135281]). Assuming a hard stone composition, this crater diameter is associated with an initial meteor radius on the order of 50 m to 100 m, based on Hills and Goda (1993, Figure 17 [DIRS 135281]), as reflected in Figure II-4b of Attachment II of this analysis report. Based on Hills and Goda (1993, Figure 9 [DIRS 135281]), the radius of the associated debris swarm (i.e., the degree of scatter of all fragments, but with lesser cratering effects, if any, than the largest fragment and thus incapable of fracturing to top of the PTn or deeper) is on the order of 0.4 to 0.5 km. This suggests a debris and/or crater field with a total encompassing area of approximately 0.5 to 0.8 km2, but with a pock-marked surface – some portion of the area is affected and some is not depending on the number of size of other fragments. This suggests that at most, only 4 to 6 percent of the total surface area of the repository (and likely significantly less) is even, potentially affected. This suggests that an argument for exclusion based on low consequence may also appropriate depending on modeling sensitivity and relative model grid size. With regard to the Paintbrush hydrologic unit outcrop area, the probability threshold is shown on Figure IV-8. The figure indicates that resulting crater diameters at the probability threshold would be less than 20 m. This represents a surface area of less than 0.001 km2, or less than 0.01 percent, of the repository surface area. The resulting effects from the radius of the debris swarm would be at the lower end of the scale of the effects just discussed. Although the total affected area would be about the same, the width of the outcrop area is no greater than 0.1 km, thus limiting the outcrop area affected by the debris swarm to no more than 0.03 km2. This would represent less than one-half percent of the repository surface area. Accordingly, this aspect of meteorite impact can also be excluded based on low consequence. Based on Hills and Goda (1993, Figure 18 [DIRS 135281]), such meteors could results in earthquakes with Richter magnitudes ranging from Magnitude 5 to slightly less than Magnitude 7 (Richter Scale). Existing seismic analyses cover this range of magnitude of events, so a meteorite-caused earthquake component would not provide additional significant hazard and is, therefore, excluded based on low consequence. A comparison of the annualized frequency curves for the three repository designs (Figures IV-7, IV-9, IV-10) indicate that there are only minor differences in probability estimates despite seemingly significant changes in the total area and the respective dimensions. The total footprint area varies from 11.2 km2 for the TSPA-SR design, to 1 km2 based on the TSPA-LA emplacement area, and as large as 18 km2 based on the TSPA-LA siting area. For sensitivity considerations, the probabilities derived for the Wuschke et al. distribution is further examined because it represents a constant slope in the distribution curve. For an 80 m diameter crater, the respective probabilities for the above-listed areas were calculated to be 3.7 × 10-9, 3.9 × 10-9, and 4.6 × 10-9. Consequently, the range of total areas increased from the TSPA-SR repository footprint by factors of 1.25 and 1.6 respectively, but the probabilities increased by factors of 1.05 and 1.24, respectively. And with respect to the TSPA-LA emplacement area, the siting area increases by a factor of 1.29 and the probability increased by a factor of about 1.18. Thus, ANL-WIS-MD-000019 REV 01 IV-64 April 2004 excluding consideration of the V=15 km/sec distribution curve, at least a doubling of the repository footprint area used for evaluating TSPA-LA would be needed before probability based on the Wuschke et al. distribution would be of concern. However, if the V=15 km/sec curve is limiting, then expansion of areas greater than that currently considered would dictate further evaluation of the consequence for potential fracturing of the PTn unit, and expansion of the repository into areas where the PTn was shallower than 60 m or non-existent would also require further examination. ANL-WIS-MD-000019 REV 01 IV-65 April 2004 INTENTIONALLY LEFT BLANK ANL-WIS-MD-000019 REV 01 IV-66 April 2004