[Federal Register: September 16, 2003 (Volume 68, Number 179)]
[Rules and Regulations]
[Page 54143-54160]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr16se03-2]
-----------------------------------------------------------------------
NUCLEAR REGULATORY COMMISSION
10 CFR Part 72
RIN 3150-AG93
Geological and Seismological Characteristics for Siting and
Design of Dry Cask Independent Spent Fuel Storage Installations and
Monitored Retrievable Storage Installations
AGENCY: Nuclear Regulatory Commission.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: The Nuclear Regulatory Commission (NRC) is amending its
licensing requirements for dry cask modes of storage of spent nuclear
fuel, high-level radioactive waste, and power reactor-related Greater
than Class C (GTCC) waste in an independent spent fuel storage
installation (ISFSI) or in a U.S. Department of Energy (DOE) monitored
retrievable storage installation (MRS). These amendments update the
seismic siting and design criteria, including geologic, seismic, and
earthquake engineering considerations. The final rule allows the NRC
and its licensees to benefit from experience gained in the licensing of
existing facilities and to incorporate rapid advancements in the earth
sciences and earthquake engineering. The amendments make the NRC
regulations that govern certain ISFSIs and MRSs more compatible with
the 1996 amendments that addressed uncertainties in seismic hazard
analysis for nuclear power plants. The amendments allow certain ISFSI
or MRS applicants to use a design earthquake level commensurate with
the risk associated with an ISFSI or MRS.
EFFECTIVE DATE: This final rule is effective on October 16, 2003.
FOR FURTHER INFORMATION CONTACT: Keith K. McDaniel, Office of Nuclear
Material Safety and Safeguards, U.S. Nuclear Regulatory Commission,
Washington, DC 20555-0001, telephone: (301) 415-5252, e-mail:
kkm@nrc.gov.
SUPPLEMENTARY INFORMATION:
I. Background
II. Objectives
III. Applicability
IV. Discussion
V. Related Regulatory Guide and Standard Review Plans
VI. Summary of Public Comments on the Proposed Rule
VII. Summary of Final Revisions
VIII. Criminal Penalties
IX. Agreement State Compatibility
X. Voluntary Consensus Standards
XI. Finding of No Significant Environmental Impact: Availability
XII. Paperwork Reduction Act Statement
XIII. Regulatory Analysis
XIV. Regulatory Flexibility Certification
XV. Backfit Analysis
XVI. Small Business Regulatory Enforcement Fairness Act
I. Background
In 1980, the NRC added 10 CFR part 72 to its regulations to
establish licensing requirements for the independent storage of spent
nuclear fuel and high-level radioactive waste (HLW) (45 FR 74693;
November 12, 1980). In 1988, the NRC amended part 72 to provide for
licensing the storage of spent nuclear fuel and HLW in an MRS (53 FR
31651; August 19, 1988). Subpart E of Part 72 contains siting
evaluation factors that must be investigated and assessed with respect
to the siting of an ISFSI or MRS, including a requirement for
evaluation of geological and seismological characteristics. ISFSI and
MRS facilities are designed and constructed for the interim storage of
spent nuclear fuel that has aged for at least one year, other
solidified radioactive materials associated with spent fuel storage,
and power reactor-related GTCC waste, that are pending shipment to a
high-level radioactive waste repository or other disposal site.
The original regulations envisioned ISFSI and MRS facilities as
spent fuel pools or single, massive dry storage structures. The
regulations required seismic evaluations equivalent to those for a
nuclear power plant (NPP) when the ISFSI or MRS is located west of the
Rocky Mountain Front (west of approximately 104[deg] west longitude),
referred to hereafter as the western U.S., or in areas of known seismic
activity east of the Rocky Mountain Front (east of approximately
104[deg] west longitude), referred to hereafter as the eastern U.S. A
seismic design requirement, equivalent to the requirements for an NPP
(appendix A to 10 CFR part 100) seemed appropriate for these types of
facilities, given the potential accident scenarios. For those sites
located in the eastern U.S., and not in areas of known seismic
activity, the regulations allowed for less stringent alternatives.
For other types of ISFSI or MRS designs, the regulation required a
site-specific investigation to establish site suitability commensurate
with the specific requirements of the proposed ISFSI or MRS. The NRC
explained that for ISFSIs which do not involve massive structures, such
as dry storage casks and canisters, the required design earthquake will
be determined on a case-by-case basis until more experience is gained
with the licensing of these types of units (45 FR 74697).
For sites located in either the western U.S. or in areas of known
seismic activity in the eastern U.S., the regulations in 10 CFR part 72
currently require the use of the procedures in appendix A to part 100
for determining the design basis vibratory ground motion at a site.
appendix A requires the use of ``deterministic'' approaches in the
development of a single set of earthquake sources. The applicant
develops for each source a postulated earthquake to be used to
determine the ground motion that can affect the site, locates the
postulated earthquake according to prescribed rules, and then
calculates ground motions at the site.
Advances in the sciences of seismology and geology, along with the
occurrence of some licensing issues not foreseen in the development of
appendix A to part 100, have caused a number of difficulties in the
application of this regulation. Specific problematic areas include the
following:
1. Because the deterministic approach does not explicitly recognize
uncertainties in geoscience parameters, probabilistic seismic hazard
analysis (PSHA) methods were developed that allow explicit expressions
for the uncertainty in ground motion estimates and provide a means for
assessing sensitivity to various parameters. Appendix A to part 100
does not allow this application.
2. The limitations in data and geologic/seismic analyses, and the
rapid evolution in geosciences have required considerable latitude in
technical judgment. The inclusion of detailed geoscience assessments in
Appendix A has inhibited the use of needed judgment and flexibility in
applying basic principles to new situations; and
3. Various sections of Appendix A are subject to different
interpretations. For example, there have been differences of opinion
and differing interpretations among experts as to the largest
earthquakes to be considered and ground motion models to be used, thus
often making the licensing process less predictable.
In 1996, the NRC amended 10 CFR parts 50 and 100 to update the
criteria
[[Page 54144]]
used in decisions regarding NPP siting, including geologic and seismic
engineering considerations for future NPPs (61 FR 65157; December 11,
1996). The amendments added a new Sec. 100.23 requiring that the
uncertainties associated with the determination of the Safe Shutdown
Earthquake Ground Motion (SSE) be addressed through an appropriate
analysis, such as a PSHA or suitable sensitivity analyses in lieu of
appendix A to part 100. This approach takes into account the
problematic areas identified above in the earlier siting requirements
and is based on developments in the technical field over the past two
decades. Further, regulatory guides have been used to address
implementation issues. For example, the NRC provided guidance for NPP
license applicants in Regulatory Guide 1.165, ``Identification and
Characterization of Seismic Sources and Determination of Safe Shutdown
Earthquake Ground Motion,'' and Standard Review Plan NUREG-0800,
``Standard Review Plan for the Review of Safety Analysis Reports for
Nuclear Power Reactors,'' Section 2.5.2, ``Vibratory Ground Motion,''
Revision 3. However, the NRC left appendix A to part 100 in place to
preserve the licensing basis for existing plants and confined the
applicability of Sec. 100.23 to new NPPs.
The NRC is now amending 10 CFR part 72 to require applicants at
some locations to address uncertainties in seismic hazard analysis by
using appropriate analyses, such as a PSHA or suitable sensitivity
analyses, for determining the design earthquake ground motion (DE). The
use of a probabilistic approach or suitable sensitivity analyses to
siting parallels the change made to 10 CFR part 100.
In comparison with an NPP, an operating dry cask ISFSI or MRS
facility storing spent nuclear fuel is a passive facility in which the
primary activities are waste receipt, handling, and storage. An ISFSI
or MRS facility does not have the variety and complexity of active
systems necessary to support safe operations at an NPP. Further, the
robust cask design required for non-seismic considerations (e.g., drop
event, shielding), assure low probabilities of failure from seismic
events. In the unlikely occurrence of a radiological release as a
result of a seismic event, the radiological consequences to workers and
the public are significantly lower than those that could arise at an
NPP. The conditions required for release and dispersal of significant
quantities of radioactive material, such as high temperatures or
pressures, are not present in an ISFSI or MRS. This is primarily due to
the low heat-generation rate of spent fuel that has undergone more than
one year of decay before storage in an ISFSI or MRS, and to the low
inventory of volatile radioactive materials readily available for
release to the environment. The long-lived nuclides present in spent
fuel are tightly bound in the fuel materials and are not readily
dispersible. Short-lived volatile nuclides, such as I-131, are no
longer present in aged spent fuel. Furthermore, even if the short-lived
nuclides were present during a fuel assembly rupture, the canister
surrounding the fuel assemblies is designed to confine these nuclides.
The standards in part 72 Subparts E, ``Siting Evaluation Factors,''
and F, ``General Design Criteria,'' ensure that the dry cask storage
designs are very rugged and robust. The casks must maintain structural
integrity during a variety of postulated non-seismic events, including
cask drops, tip-over, and wind driven missile impacts. These non-
seismic events challenge cask integrity significantly more than seismic
events. Therefore, the casks have substantial design margins to
withstand forces from a seismic event greater than the design
earthquake.
Hence, the seismically induced risk from the operation of an ISFSI
or MRS is less than at an operating NPP. As a result, the NRC is
revising the DE requirements for ISFSI and MRS facilities from the
current part 72 requirements, which are equivalent to the SSE for an
NPP.
As an additional minor change, the NRC is modifying Sec.
72.212(b)(2)(i)(B) to require general licensees to evaluate dynamic
loads, in addition to static loads, in the design of cask storage pads
and areas for ISFSIs, to ensure that casks are not placed in unanalyzed
conditions. Accounting for dynamic loads in the analysis of ISFSI pads
and areas will ensure that pads continue to support the casks during
seismic events. General licensees currently evaluate dynamic loads for
evaluating the casks, pads and areas, to meet the cask design bases in
the Certificate of Compliance, as required by Sec. 72.212(b)(2)(i)(A).
Therefore, the rule will not actually require any general licensees
operating an ISFSI to re-perform any written evaluations previously
undertaken. Specific licensees are currently required, under Sec.
72.122(b)(2), to design ISFSIs to withstand the effects of dynamic
loads, such as earthquakes and tornados.
The NRC published the proposed rule, ``Geological and Seismological
Characteristics for Siting and Design of Dry Cask Independent Spent
Fuel Storage Installations and Monitored Retrievable Storage
Installations'' in the Federal Register on July 22, 2002 (67 FR 47745)
for public comment. The NRC stated on September 5, 2002 (67 FR 56876)
that it intended to extend the comment period for an additional 15 days
to allow interested persons additional time to provide meaningful
comments. The public comment period expired on October 22, 2002.
The NRC received nine comment letters on the proposed rule. These
comments and the NRC responses are discussed in Section VI of this
document, ``Summary of Public Comments on the Proposed Rule.''
II. Objectives
An ISFSI is designed, constructed, and operated under a part 72
specific or general license. A part 72 specific license for an ISFSI is
issued to a named person upon application filed under part 72
regulations. A part 72 general license for an ISFSI is issued under 10
CFR 72.210 to persons authorized to possess an NPP license under part
50, without filing a part 72 license application. A general licensee is
required to meet the conditions specified in subpart K of part 72. An
MRS may be designed, constructed, and operated by DOE under a part 72
specific license.
The final rule reflects changes that are intended to (1) provide
benefit from the experience gained in applying the existing regulation
and from research; (2) provide needed regulatory flexibility to
incorporate into licensing state-of-the-art improvements in the
geosciences and earthquake engineering; and (3) make the regulations
more risk informed, consistent with the Commission's recent policy.
The objectives of this final rule are to:
1. Require a new specific-license applicant for a dry cask storage
facility located in either the western U.S. or in areas of known
seismic activity in the eastern U.S., and not co-located with an NPP,
to address uncertainties in seismic hazard analysis by using
appropriate analyses, such as a PSHA or suitable sensitivity analyses,
for determining the DE. All other new specific-license applicants for
dry cask storage facilities will have the option of complying with the
requirement to use a PSHA or suitable sensitivity analyses to address
uncertainties in seismic hazard analysis, or other options compatible
with the existing regulation. (Sec. 72.103)
2. Allow new ISFSI or MRS specific-license applicants using a PSHA
to select a DE appropriate for and commensurate with the risk
associated with an ISFSI or MRS; and
[[Page 54145]]
3. Require general licensees to design cask storage pads and areas
to adequately account for dynamic loads, in addition to static loads.
(Sec. 72.212)
III. Applicability
This section clarifies the applicability of the new Sec. 72.103
for Part 72 specific licensees, and modified Sec. 72.212(b)(2)(i)(B)
for Part 72 general licensees.
Applicability of New Sec. 72.103
(1) Applicants who apply on or after the effective date of the
final rule, for a part 72 specific license for a dry cask storage ISFSI
or MRS, located in either the western U.S. or in areas of known seismic
activity in the eastern U.S., and not co-located with an NPP, will be
required to address uncertainties in seismic hazard analysis by using
appropriate analyses, such as a PSHA or suitable sensitivity analyses,
for determining the DE.
(2) Applicants who apply on or after the effective date of the
final rule, for a part 72 specific license for a dry cask storage ISFSI
or MRS, located in either the western U.S. or in areas of known seismic
activity in the eastern U.S., and co-located with an NPP, will have the
option of addressing uncertainties in seismic hazard analysis by using
appropriate analyses, such as a PSHA or suitable sensitivity analyses,
or using the existing design criteria for the NPP, for determining the
DE. When the existing design criteria for the NPP are used for an ISFSI
at a site with multiple NPPs, the criteria for the most recent NPP must
be used.
(3) Applicants who apply on or after the effective date of the
final rule, for a part 72 specific license for a dry cask storage ISFSI
or MRS, located in the eastern U.S., except in areas of known seismic
activity, will have the option of addressing uncertainties in seismic
hazard analysis by using appropriate analyses, such as a PSHA or
suitable sensitivity analyses, or using a standardized DE described by
an appropriate response spectrum anchored at 0.25 g (subject to the
conditions in new Sec. 72.103(a)(1)), or using the existing design
criteria for the most recent NPP (if applicable), for determining the
DE.
(4) The new Sec. 72.103 is not applicable to a general licensee at
an existing NPP operating an ISFSI under a part 72 general license
anywhere in the U.S.
The changes apply to the design basis of both a dry cask storage
type ISFSI and MRS, because these facilities are similar in design. The
NRC does not intend to revise the 10 CFR part 72 geological and
seismological criteria as they apply to wet modes of storage because
applications for this means of storage are not expected and it is not
cost-effective to allocate resources to develop the technical bases for
such an expansion of the rulemaking. The NRC also does not intend to
revise the 10 CFR part 72 geological and seismological criteria as they
apply to dry modes of storage that do not use casks because of the lack
of experience in licensing these types of facilities.
The applicability of Sec. 72.103 is summarized in the table below.
Applicability of Amended Sec. 72.212(b)(2)(i)(B)
The changes in Sec. 72.212(b)(2)(i)(B), regarding the evaluation
of dynamic loads for the design of cask storage pads and areas, will
apply to all general licensees for an ISFSI.
The applicability of the modified Sec. 72.212(b)(2)(i)(B) is
summarized in the table below.
Summary of Applicability
[Design Earthquake Ground Motion for ISFSI or MRS Specific-License
Applicants for Dry Cask Modes of Storage on or after the Effective Date
of the Final Rule]
------------------------------------------------------------------------
Site condition Specific-license applicant \1\
------------------------------------------------------------------------
Western U.S., or areas of known seismic Must use PSHA or suitable
activity in the eastern U.S., not co- sensitivity analyses to
located with NPP. account for uncertainties in
seismic hazards inevaluations
\2\.
Western U.S., or areas of known seismic PSHA or suitable sensitivity
activity in the eastern U.S., and co- analyses to account for
located with NPP. uncertainties in seismic
hazards evaluations \2\,
or
existing NPP design criteria
(multi-unit sites--use and co-
located withthe most recent
criteria). NPP
Eastern U.S., and not in areas of known PSHA or suitable sensitivity
seismic activity. analyses to account for
uncertainties in seismic
hazards evaluations,\2\
or
existing NPP design criteria,
if applicable (multi-unit
sites--use the most recent
criteria),
or
an appropriate response
spectrum anchored at 0.25g
(subject to the conditions in
new Sec. 72.103(a)(1)).
------------------------------------------------------------------------
\1\ New Sec. 72.103 does not apply to general licensees. General
licensees must satisfy the conditions specified in 10 CFR 72.212.
\2\ Regardless of the results of the investigations anywhere in the
continental U.S., the DE must have a value for the horizontal ground
motion of no less than 0.10 g with the appropriate response spectrum.
IV. Discussion
The NRC is amending certain sections of part 72 dealing with
seismic siting and design criteria for a dry cask ISFSI or MRS. The NRC
intends to leave the present Sec. 72.102 in place to preserve the
ISFSI licensing bases for applications before the effective date of the
rule, and continue the present ISFSI or MRS licensing bases for
applications for other than dry cask modes of storage. The NRC is
changing the heading of Sec. 72.102, adding a new Sec. 72.103, and
modifying Sec. 72.212(b)(2)(i)(B).
A. Change to 10 CFR 72.102
The heading of Sec. 72.102 will be changed to clarify that the
present requirements are applicable to ISFSI or MRS specific licensees
or specific-license applicants before the effective date of the rule.
The requirements of Sec. 72.102 that applied to ISFSI or MRS
licensees, or license applicants for other than dry cask modes of
storage will continue to apply.
B. New 10 CFR 72.103
New Sec. 72.103 describes the seismic requirements for new
specific-license applicants for dry cask storage at an ISFSI or MRS.
[[Page 54146]]
1. Remove Detailed Guidance From the Regulation
Part 72 currently requires license applicants for an ISFSI or MRS,
in the western U.S. or in other areas of known seismicity, to comply
with appendix A to part 100. Appendix A contains both requirements and
guidance on how to satisfy those requirements. For example, Section IV,
``Required Investigations,'' of Appendix A states that investigations
are required for vibratory ground motion, surface faulting, and
seismically induced floods and water waves. Appendix A then provides
detailed guidance on what constitutes an acceptable investigation. A
similar situation exists in Section V, ``Seismic and Geologic Design
Bases,'' of appendix A to part 100.
Geoscience assessments require considerable latitude in judgment
because of (a) limitations in data; (b) changing state-of-the-art of
geologic and seismic analyses; (c) rapid accumulation of knowledge; and
(d) evolution in geoscience concepts. The NRC recognized the need for
latitude in judgment when it amended part 100 in 1996.
However, specifying geoscience assessments in detail in a
regulation has created difficulty for applicants and the NRC by
inhibiting needed latitude in judgment. It has inhibited the
flexibility needed in applying basic principles to new situations and
the use of evolving methods of analyses (for instance, probabilistic)
in the licensing process.
The NRC is adding a new section in part 72 that will provide
specific siting requirements for an ISFSI or MRS instead of referencing
another part of the regulations. The amended regulation will also
reduce the level of detail by placing only basic requirements in the
rule and providing the details on methods acceptable for meeting the
requirements in an accompanying guidance document. Thus, the revised
regulation contains requirements to:
(i) Evaluate the geological, seismological, and engineering
characteristics of the proposed site;
(ii) Establish a DE; and
(iii) Identify the uncertainties associated with these
requirements.
Detailed guidance on the procedures acceptable to the NRC for
meeting the requirements are provided in Regulatory Guide 3.73, ``Site
Evaluations and Design Earthquake Ground Motion for Dry Cask
Independent Spent Fuel Storage and Monitored Retrievable Storage
Installations.''
2. Address Uncertainties and Use Probabilistic Methods
The existing approach for determining a DE for an ISFSI or MRS,
embodied in Appendix A to Part 100, relies on a ``deterministic''
approach. Using this deterministic approach, an applicant develops a
single set of earthquake sources, develops for each source a postulated
earthquake to be used as the source of ground motion that can affect
the site, locates the postulated earthquake according to prescribed
rules, and then calculates ground motions at the site.
Although this approach has worked reasonably well for the past
several decades in the sense that the SSE for NPPs sited with this
approach are judged to be suitably conservative, the approach has not
explicitly recognized uncertainties in geosciences parameters. Because
so little is known about earthquake phenomena (especially in the
eastern U.S.), there have been differences of opinion and differing
interpretations among experts as to the largest earthquakes to be
considered and ground-motion models to be used, often making the
licensing process less predictable.
Probabilistic methods that have been developed in the past 15 to 20
years for evaluation of seismic safety of nuclear facilities allow
explicit incorporation of different models for zonation, earthquake
size, ground motion, and other parameters. The advantage of using these
probabilistic methods is their ability to incorporate different models
and data sets, thereby providing an explicit expression for the
uncertainty in the ground motion estimates and a means of assessing
sensitivity to various input parameters. The western and eastern U.S.
have fundamentally different tectonic environments and histories of
tectonic deformation. Consequently, application of these probabilistic
methodologies has revealed the need to vary the fundamental PSHA
methodology depending on the tectonic environment of the site.
In 1996, when the NRC accepted the use of a PSHA methodology or
suitable sensitivity analyses in Sec. 100.23, it recognized that the
uncertainties in seismological and geological information must be
formally evaluated and appropriately accommodated in the determination
of the SSE for seismic design of NPPs. The NRC further recognized that
the nature of uncertainty and the appropriate approach to account for
it depends on the tectonic environment of the site and on properly
characterizing parameters input to the PSHA. Methods other than
probabilistic methods (PSHA), such as sensitivity analyses, may be
adequate for some sites to account for uncertainties. The NRC believes
that certain new applicants for ISFSI or MRS specific licenses, as
described in Section III, ``Applicability,'' of this document, must use
probabilistic methods or other sensitivity analyses to account for
uncertainties instead of using Appendix A to Part 100. The NRC does not
intend to require new ISFSI or MRS specific-license applicants that are
co-located with an NPP to address uncertainties because the criteria
used to evaluate existing NPPs are considered to be adequate for
ISFSIs, in that the criteria have been determined to be safe for NPP
licensing, and the seismically induced risk of an ISFSI or MRS is
considerably lower than that of an NPP, as described in Section IV of
this document.
The key elements of the NRC's approach for seismic and geologic
siting for ISFSI or MRS license review and approval consists of:
a. Conducting site-specific and regional geoscience investigations;
b. Setting the target exceedance probability commensurate with the
level of risk associated with an ISFSI or MRS;
c. Conducting PSHA and determining ground motion level
corresponding to the target exceedance probability;
d. Determining if other sources of information change the available
probabilistic results or data for the site; and
e. Determining site-specific spectral shape, and scaling this shape
to the ground motion level determined above.
In addition, the NRC will review the application using all
available data including insights and information from previous
licensing experience. Thus, the revised approach requires thorough
regional and site-specific geoscience investigations. Results of the
regional and site-specific investigations must be considered in
applying the probabilistic method. Two current probabilistic methods
are the NRC-sponsored study conducted by Lawrence Livermore National
Laboratory and the Electric Power Research Institute's seismic hazard
study. These are essentially regional studies. The regional and site-
specific investigations provide detailed information to update the
database of the hazard methodology to make the probabilistic analysis
site-specific.
Applicants must also incorporate local site geological factors,
such as stratigraphy and topography, and account for site-specific
geotechnical properties in establishing the DE. Guidelines to
incorporate local site factors and advances in ground motion
[[Page 54147]]
attenuation models, and to determine ground motion estimates, are
outlined in NUREG-0800, Section 2.5.2.
Methods acceptable to the NRC for implementing the revised
regulation related to the PSHA or suitable sensitivity analyses are
described in RG 3.73.
3. Revise the Design Earthquake Ground Motion
The present DE in part 72 is based on the deterministic
requirements contained in Appendix A to 10 CFR Part 100 for NPPs. In
the Statement of Considerations accompanying the initial part 72
rulemaking, the NRC recognized that the required design earthquake need
not be as high as for an NPP and should be determined on a ``case-by-
case'' basis until ``more experience is gained with licensing of these
types of units'' (45 FR 74697; November 12, 1980). With the advances in
probabilistic seismic hazard evaluation techniques, over 10 years of
experience in licensing dry cask storage (10 specific licenses have
been issued and 9 locations use the general license provisions), and
analyses demonstrating robust behavior of dry cask storage systems
(DCSSs) in accident scenarios, the NRC now has a reasonable basis to
consider more appropriate DE parameters for a dry cask ISFSI or MRS.
Therefore, in those instances when an ISFSI or MRS specific-license
applicant uses PSHA methods, the NRC will allow a DE commensurate with
the lower risk associated with these facilities.
I. Factors that result in the lower radiological risk at an ISFSI
or MRS compared to an NPP include the following:
a. In comparison with an NPP, an operating ISFSI or MRS is a
passive facility in which the primary activities are waste receipt,
handling, and storage. An ISFSI or MRS does not have the variety and
complexity of active systems necessary to support an operating NPP.
After the spent fuel is in place, an ISFSI or MRS is essentially a
static operation.
b. During normal operations, the conditions required for the
release and dispersal of significant quantities of radioactive
materials are not present. There are no components carrying fluids at
high temperatures or pressures during normal operations or under design
basis accident conditions to cause the release and dispersal of
radioactive materials. This is primarily due to the low heat-generation
rate of spent fuel that has undergone more than one year of decay
before storage in an ISFSI or MRS, and to the low inventory of volatile
radioactive materials readily available for release to the environment.
c. The long-lived nuclides present in spent fuel are tightly bound
in the fuel materials and are not readily dispersible. Short-lived
volatile nuclides, such as I-131, are no longer present in aged spent
fuel. Furthermore, even if the short-lived nuclides were present during
a fuel assembly rupture, the canister surrounding the fuel assemblies
would confine these nuclides. Therefore, the NRC believes that the
seismically induced radiological risk associated with an ISFSI or MRS
is significantly less than the risk associated with an NPP.
II. Additional rationale for allowing the use of a DE level
commensurate with the risk associated with an ISFSI or MRS includes the
following:
a. Because the DE is defined as a smooth broad-band spectrum, which
envelops the controlling earthquake responses, the vibratory ground
motion specified is conservative.
b. To evaluate dry cask storage systems' behavior during an
earthquake, typical storage systems (one a cylindrical cask, HI-STORM
100, the other a concrete module type, NUHOMS) were analyzed for a
range of earthquakes. Based on the results of the analyses, the NRC has
concluded that a free-standing dry storage cask remains stable and will
not tip-over, or would not slide and impact the adjacent casks during
an earthquake approximately equal to the magnitude of a SSE for an NPP.
Additionally, parametric studies indicated that dry cask storage
systems have significant margins against tip-over and sliding, to
withstand an earthquake significantly higher in magnitude than the SSE
for an NPP, without releasing radioactivity. Further, a cask is
analyzed for a non-mechanistic tip-over event during an earthquake, to
verify that it would maintain its structural integrity, and
radioactivity from spent fuel would not be released to the environment.
Therefore, based on drop accident analyses and non-mechanistic tip-over
event evaluations, and on the results of the generic studies for the
cask behavior during an earthquake, it can be concluded that there
would be no radiological consequences at a dry cask ISFSI or MRS
facility due to an earthquake.
c. The rational for allowing a DE for an ISFSI or MRS to be lower
than a DE for an NPP is consistent with the approach used in DOE
Standard DOE-STD-1020, ``Natural Phenomena Hazards Design Evaluation
Criteria for Department of Energy Facilities.''
Regulatory Guide 3.73 (formerly DG-3021) recommends an acceptable
mean annual probability of exceedance (MAPE) for the DE that is
commensurate with the lower risk associated with an ISFSI or MRS as
compared to an NPP. The basis for the recommendation is provided in a
report entitled, ``Selection of the Design Earthquake Ground Motion
Reference Probability''. This report may be accessed through the NRC's
Public Electronic Reading Room on the Internet at http://www.nrc.gov/reading-rm/adams.html.
If you do not have access to ADAMS or if there
are problems in accessing the documents located in ADAMS, contact the
NRC's PDR reference staff at 1-800-397-4209, 301-415-4737, or by email
to pdr@nrc.gov. Discussion on the recommended mean annual probability
of exceedance is also in Section VI of this FRN, ``Summary of Public
Comments on the Proposed Rule.''
C. Change to 10 CFR 72.212(b)(2)(i)(B)
The NRC is modifying Sec. 72.212(b)(2)(i)(B) to require that
general licensees evaluate dynamic loads, in addition to static loads,
in the design of cask storage pads and areas for ISFSIs to ensure that
casks are not placed in unanalyzed conditions. During a seismic event,
the cask storage pads and areas experience dynamic loads in addition to
static loads. The dynamic loads depend on the interaction of the casks,
cask storage pads, and areas. Consideration of the dynamic loads of the
stored casks, in addition to the static loads, for the design of the
cask storage pads and areas, will ensure that the cask storage pads and
areas will perform satisfactorily during a seismic event.
The revision will also require consideration of potential
amplification of earthquakes through soil-structure interaction, and
soil liquefaction potential or other soil instability due to vibratory
ground motions. Depending on the properties of soil and structures, the
free-field earthquake acceleration input loads may be amplified at the
top of the storage pad. These amplified acceleration input values must
be bound by the design bases seismic acceleration values for the cask,
specified in the Certificate of Compliance. Liquefaction of the soil
and instability during vibratory motion due to an earthquake may affect
the cask stability.
The changes to Sec. 72.212 will not actually impose a new burden
on the general licensees because they currently need to consider
dynamic loads to meet the requirements in Sec. 72.212(b)(2)(i)(A).
Section 72.212(b)(2)(i)(A) requires that general licensees perform
written evaluations to meet conditions set forth in the cask
Certificate of Compliance. These Certificates of Compliance require
that dynamic loads, such as seismic and
[[Page 54148]]
tornado loads, be evaluated to meet the cask design bases. Specific
licensees are currently required, under Sec. 72.122(b)(2), to design
ISFSIs to withstand the effects of dynamic loads, such as earthquakes
and tornados.
V. Related Regulatory Guide and Standard Review Plans
On July 22, 2002, the NRC published DG-3021, ``Site Evaluations and
Determination of Design Earthquake Ground Motion for Seismic Design of
Independent Spent Fuel Storage Installations and Monitored Retrievable
Storage Installations'' for public comment (67 FR 48956; July 26,
2002). Regulatory Guide 3.73, Site Evaluations and Design Earthquake
Ground Motion for Dry Cask Independent Spent Fuel Storage and Monitored
Retrievable Storage Installations (formerly DG-3021), provides guidance
to licensees for procedures acceptable to the NRC staff for:
(1) Conducting a detailed evaluation of site area geology and
foundation stability;
(2) Conducting investigations to identify and characterize
uncertainty in seismic sources in the site region important for the
probabilistic seismic hazard analysis (PSHA);
(3) Evaluating and characterizing uncertainty in the parameters of
seismic sources;
(4) Conducting PSHA for the site; and
(5) Determining the DE to satisfy the requirements of 10 CFR Part
72.
This guide describes acceptable procedures and provides a list of
references that present acceptable methodologies to identify and
characterize capable tectonic sources and seismogenic sources. Section
IV.B of this SUPPLEMENTARY INFORMATION describes the key elements of
the regulatory guide. A document announcing the availability of
Regulatory Guide 3.73 will be published in the Federal Register in the
near future.
Requests for single copies of active regulatory guides (which may
be reproduced) or for placement on an automatic distribution list for
single copies of future guides should be made in writing to the U.S.
Nuclear Regulatory Commission, Washington, DC 20555, Attention:
Reproduction and Distribution Services Section, or by fax to (301) 415-
2289; email distribution@nrc.gov. Copies are available for inspection
or copying for a fee from the NRC Public Document Room at 11555
Rockville Pike (first floor), Rockville, MD; the PDR's mailing address
is U.S. NRC PDR, Washington, DC 20555; telephone (301) 415-4737 or 1-
(800) 397-4209; fax (301) 415-3548; e-mail pdr@nrc.gov. In the future, editorial changes to NUREG-1536, ``Standard Review
Plan for Dry Cask Storage Systems,'' and NUREG-1567, ``Standard Review
Plan for Spent Fuel Dry Storage Facilities,'' will be made. For
example, the standard review plans will be updated to reference the new
Sec. 72.103 and Regulatory Guide 3.73.
VI. Summary of Public Comments on the Proposed Rule
This section presents a summary of the public comments received on
the proposed rule and supporting documents, the NRC's response to the
comments, and changes made in the final rule and supporting documents
as a result of these comments.
The NRC received nine comment letters on the proposed rule from
eight commenters. The commenters were the Nuclear Energy Institute
(NEI), the U.S. Department of Energy (DOE), two nuclear power
utilities, three State agencies, and one license applicant for an
independent spent fuel storage installation. All the commenters agreed
with the proposal to address uncertainty by requiring the use of a PSHA
or suitable sensitivity analyses for an ISFSI or MRS in the western
U.S., not co-located with an NPP, and in areas of known seismic
activity in the eastern U.S. However, commenters were divided on the
specific question for public comment related to the appropriate value
for the MAPE posed by the Commission in the proposed rule. These
comments are summarized in this section under the heading ``Related
Regulatory Guide.'' All commenters supported the concept of requiring
general licensees to evaluate both dynamic loads and static loads for
ISFSI and MRS cask storage pads and areas.
Copies of the public comments are available for review in the NRC
Public Document Room, 11555 Rockville Pike, Rockville, MD. A review of
the comments and the NRC responses follow:
General Comments
Comment 1: A commenter stated that proposed 10 CFR 72.103(f)(1)
does not comply with the notice and comment requirements of Section 553
of the Administrative Procedure Act (APA) because of the way the rule
is structured. The commenter believes that the proposed rule ``is in
the guise of a substantive rule,'' but that the substantive
requirements are found in the draft guidance, a document which is not a
rule. In the commenter's view, ``the Commission attempts to give
concrete form to its proposed rule through an interpretative document,
DG-3021, and the Commission thereby circumvents [APA] Sec. 553 notice
and comment rulemaking procedures,'' citing Paralyzed Veterans of
America v. D.C. Arena L.P., 117 F.3d 579 (D.C. Cir. 1997). According to
the commenter, a significant defect of this structure is that the rule
gives no standards against which a licensing board or intervenors may
evaluate whether an applicant has complied with the rule and, instead,
gives ``unbridled and unchecked discretion to the staff in determining
the seismic design standard for ISFSIs sited in seismic areas.'' The
proposed rule, in the commenter's view, has no force of law because it
has no binding standards and thus is unenforceable. Another commenter
disagreed and supported the NRC's view that the rule is substantive and
in compliance with the APA.
Response: First, the NRC rejects the claim that the rule is not
being promulgated in compliance with Sec. 553 of the APA. Section 553
requires that notice of a proposed rulemaking be published in the
Federal Register, including the terms or substance of the proposed
rule, and that interested persons be given an opportunity to comment.
The APA also provides an exception for interpretative rules and general
statements of policy enabling those documents to be issued as final
rules without prior notice and comment. In this case, the NRC has not
availed itself of the exception but rather has issued both the draft
guidance and the proposed rule for public comment. Thus, there has been
no violation of the notice and comment requirements of Section 553 of
the APA even if the guidance were to be considered part of the rule.
The Paralyzed Veterans case, cited by the petitioner, concerned a
guidance document issued by the Department of Justice which had been
issued without prior notice and comment and raised the issue whether
the Government could rely upon the guidance in an enforcement action.
The court ultimately found that there was no need for the Government to
rely on the guidance to enforce the regulation. Here, the guidance has
been issued for comment and the NRC does not contend, as explained
below, that the guidance is legally enforceable.
Second, the NRC does not agree that ``substantive requirements''
have been placed in the guidance document. Regulatory Guide 3.73
(formerly DG-3021) provides information on methods acceptable to the
NRC for implementing specific parts of the rule, but it does not place
any particular requirements on
[[Page 54149]]
applicants. As the commenter points out, ``staff regulatory guides are
not regulations, do not have the force of regulations, and when
challenged, are considered only one way in which an applicant may meet
the regulations.''
Finally, the commenter really appears to be objecting to the NRC's
risk-informed, performance-based approach in this rulemaking in lieu of
the deterministic approach for determining a design earthquake embodied
in Appendix A to 10 CFR Part 100. The overall performance criteria for
protection against environmental conditions and natural phenomena in
the design of Part 72 facilities are contained in 10 CFR 72.122(b) of
the NRC's regulations. In particular, Sec. 72.122(b)(2)(i) provides:
Structures, systems, and components important to safety must be
designed to withstand the effects of natural phenomena such as
earthquakes * * * without impairing their capability to perform
their intended design functions. The design bases for these
structures, systems, and components must reflect:
(A) Appropriate consideration of the most severe of the natural
phenomena reported for the site and surrounding area, with
appropriate margins to take into account the limitations of the data
and the period of time in which the data have accumulated; and
(B) Appropriate combinations of the effects of normal and
accident conditions and the effects of natural phenomena.
These performance criteria are supplemented by the requirements of
10 CFR 72.103 governing selection of a site and determination of a DE.
This new regulation provides specific siting requirements for an ISFSI
or MRS instead of referencing another part of the regulations (Appendix
A to Part 100). This new regulation also reduces the level of detail by
placing only basic requirements in the rule and providing the details
on methods acceptable for meeting the requirements in an accompanying
guidance document. Thus, the new 10 CFR 72.103(f) establishes basic
requirements for determining a DE for use in the design of structures,
systems, and components of the ISFSI or MRS. These regulations include
a requirement that the geological, seismological, and engineering
characteristics of a proposed site and its environs be investigated in
sufficient scope and detail to provide sufficient information to
support evaluations performed to arrive at estimates of the DE (Sec.
72.103(f)(1)); a requirement that a DE be determined for the site
(Sec. 72.103(f)(2)); and a requirement that uncertainties be addressed
through an appropriate analysis, such as a probabilistic seismic hazard
analysis or suitable sensitivity analyses (Sec. 72.103(f)(2)(i)). The
regulation further requires determinations of the potential for surface
tectonic and nontectonic deformations (Sec. 72.103(f)(2)(ii)); the
design bases for seismically induced floods and water waves (Sec.
72.103(f)(2)(iii)); and the siting factors for other design conditions,
such as liquefaction potential (Sec. 72.103(f)(2)(iv)), as well as a
requirement that the DE must have a value for the horizontal ground
motion of no less than 0.10 g with the appropriate response spectrum
(Sec. 72.103(f)(3)). More specific guidance for meeting these
standards, including guidance on an acceptable reference probability,
is provided in Regulatory Guide 3.73 (formerly DG-3021).
Determining whether an applicant has complied with these
performance standards may be more difficult than would be the case with
a prescriptive regulation; however, that does not mean that the NRC has
``unbridled discretion'' in deciding whether the standards are met nor
that the standards (as opposed to the guidance) are not binding. The
NRC uses informed technical judgment to determine if an application has
satisfactorily met the standards. The NRC's rationale and judgment are
expressed in a safety evaluation report (SER) subject to evaluation and
potential challenge by members of the public. In the event of a
hearing, a licensing board would have the technical skills necessary to
evaluate any conflicting claims.
Comment 2: A commenter noted that, although the NRC's approach is
similar to that used in the amendments issued for seismic evaluation
for the siting of NPPs, the NRC has no compelling reason to follow that
approach. First, the commenter argued, if the approach violates the
APA, it should be rejected. Second, the commenter stated that because
no new applications for siting NPPs have been submitted using the new
requirements, the rule has not been put to the test. Finally, the
commenter indicated that there are no data for ISFSIs that establish
design basis ground motions, unlike the SSE for a nuclear power plant,
which has at least some data to provide guidance to the NRC and the
public.
Response: First, the NRC disagrees that either the amendments
issued for the seismic evaluation of siting of NPPs or these Part 72
amendments have been issued in violation of the APA. See comment 1.
Second, although no new license applications for siting of NPPs have
been received to test the new requirements in 10 CFR Sec. 100.23, the
guidance associated with the use of probabilistic methods for siting of
NPPs (Regulatory Guide 1.165) has been used in the PSHA prepared for a
proposed ISFSI site. It is also being followed by applicants for an
early site permit under 10 CFR Part 52. Finally, the NRC agrees that
there are limited data for ISFSIs that establish design basis ground
motions because the current Part 72 regulations for seismic design of
ISFSIs are conservatively based on the nuclear power plant seismic
design criteria, and thus, are not risk-informed. However, experience
has been gained in the design and construction of numerous facilities
using the philosophy of a graded, risk-informed approach described in
the standard building codes, similar to the approach proposed in the
rule for ISFSIs. The graded risk-informed approach is also used by the
Department of Energy in designing its facilities for seismic loads with
risks varying from conventional facilities to NPPs.
Comment 3: A commenter noted that if clear seismic standards are
not established in the rule, the opportunity for interested persons to
participate in a licensing proceeding involving the seismic design of
an ISFSI will become essentially prohibited. This is because a panoply
of specific expertise is needed to evaluate the seismic design and
there is only a small universe of seismic experts. Utilizing these
experts is often not feasible because of the financial burden on
intervenors in obtaining highly specialized expertise to analyze
probabilistic seismic risks and design of nuclear facilities.
Response: The NRC believes the standards for ISFSI or MRS facility
earthquake designs are clear. See the response to Comment 1. However,
the NRC recognizes that the proposed use of the probabilistic methods
in seismic design of ISFSIs is more complex than the current
deterministic methods of 10 CFR Part 100 Appendix A, and would require
specific expertise to participate in the licensing proceedings. The NRC
staff's safety evaluation report (SER) that independently assesses the
applicant's method of compliance with regulations is available to
assist the public in evaluating the risk of the facility and could help
intervenors to focus their resources. The NRC does not intend to limit
public participation in the licensing process; however, the Congress
has barred the use of appropriated funds to pay the expenses of, or
otherwise compensate, parties who intervene in NRC regulatory or
adjudicatory proceedings.
Comment 4: A commenter stated that the proposed rule placed too
much stock on the integrity of the dry storage cask. The commenter
indicated that of
[[Page 54150]]
the 19 ISFSI licenses issued in the past decade, none were in seismic
areas. The NRC has not licensed unanchored cylindrical casks in any
seismic areas. The commenter noted that there are no performance data,
test data, or earthquake experience data for dry casks or for ISFSIs.
The commenter further stated that the rule is based on principles that
are antithetical to earthquake engineering principles because, for
unanchored casks, the NRC relies solely on the predictions of non-
linear computer models. The commenter also stated that, up to this
point, the non-linear computer model predictions of the seismic
behavior of casks have not been validated with shake table data or
actual performance data. The commenter also stated that without
adequate and reliable performance and test data, it cannot be
determined if the casks will actually provide the critical barrier
described and relied upon in the rule. Another commenter stated that
non-linear dynamic analyses are inherently reliable. Further, the
commenter noted that proper input parameters for cask stability
analyses are not elusive unknowns but can be determined from basic
physical principles, and that these analyses have been shown not to be
highly sensitive to changes in input parameters. Therefore, the
commenter argued, shake table testing is unnecessary.
Response: The integrity of the dry storage cask during an
earthquake is a key to protecting the health and safety of the public
because it confines the radioactivity during a potential accident
event, such as an earthquake, and prevents it from being dispersed into
the environment. Contrary to traditional building designs, the cask
design is not governed by stresses resulting from an earthquake, but is
governed by requirements resulting from shielding, thermal,
criticality, and postulated handling accidents. Therefore, the critical
performance requirement for a cask is that it would remain stable and
not displace excessively to impact adjacent casks. The cask stability
can be determined by nonlinear dynamic analyses, considering
uncertainties in engineering parameters, and using multiple computer
codes. The NRC has also performed structural analyses of casks tipping
and sliding. In neither case did the canister fail.
It is a common engineering practice to design and build structures,
including new design concepts, based on detailed structural analyses
using sound engineering principles and laws of physics, without
performing confirmatory experiments. For example, new concepts in
structural designs and construction of landmark structures, such as the
Sears Tower, Hancock Tower, Eiffel Tower, and space vehicles were based
solely on analyses.
The advent of computers has helped in the development of analytical
tools, including the non-linear dynamic analyses. Results of these
analyses are being used to design structures more complex than a dry
storage cask. The concept of free-standing casks is not new. The
buildings the NRC uses every day are free-standing on a foundation, and
thus would move during an earthquake. The analytical tools for non-
linear structural analyses are verified and validated using multiple
computer codes and available experimental data. Therefore, shake table
tests or actual performance data are not necessary.
Comment 5: A commenter requested a rule to establish a definitive
design basis earthquake at a return period level [the return period of
an earthquake is an inverse of the mean annual probability of
exceedance (MAPE) of the earthquake] greater than 2,000 years that is
tied to defined risk and performance goals.
Response: The NRC does not agree that we must establish a
definitive design basis earthquake by rule. The current regulations in
Sec. 72.122(b)(2)(i), require that the structures, systems, and
components of an ISFSI or MRS must be designed to withstand the effects
of natural phenomena, such as earthquakes, without impairing their
capability to perform their intended design functions. For earthquakes,
these requirements are then supplemented by the requirements at
Sec. Sec. 72.102, 72.103, and 72.122 for detailed site investigations
and appropriate consideration of the most severe of the natural
phenomena and associated probability of occurrence, including
consideration of uncertainties, in the prediction of earthquakes. This
approach is consistent with the NRC's philosophy of using risk-
informed, performance-based regulations. In a risk-informed,
performance-based approach, the design of the ISFSI or MRS facility is
based on an assessment of the radiological risk (potential for adverse
consequences) due to an earthquake. Thus, specifying a value for the
reference probability in the rule would preclude applicants from
considering structures, systems, and components with risks other than
the risk associated with the specified reference probability.
Comment 6: A commenter stated that the supplementary information in
the final rule should state that the NRC's policy for promulgating
risk-informed regulations was a primary motivation for the rule
changes.
Response: The NRC agrees that the supplementary information for the
final rule should more clearly state that the rule was amended, in
part, to conform to the Commission's recent policy to increase the use
of risk insights and information in its regulatory applications. An
additional statement has been added to Section II, Objectives, of the
Supplementary Information portion of this document, that states the
intent to revise the regulation in accordance with this policy.
Applicability of Proposed Sec. 72.103
Comment 7: A commenter requested clarification of the proposed rule
so that applicants for an ISFSI co-located with an NPP have the option
of using the existing DE of the NPP without any further evaluations and
that this applies to all sections of the rule. The commenter pointed
out that the proposed amendments at Sec. Sec. 72.103(a)(2) and
72.103(b), as well as explanatory statements made in the proposed rule
indicate that applicants for an ISFSI that are co-located with an NPP
have the option of using the existing NPP design criteria without
additional evaluations, but that this option is not identified in Sec.
72.103(f).
Response: To further clarify the NRC's intent that an applicant for
an ISFSI that is co-located with an NPP has the option of using the
existing DE of the NPP without the need to undertake any additional
evaluations of the sort described in Sec. 72.103(f), the introductory
phrase of that section has been modified so that it now reads: ``Except
as provided in paragraphs (a)(2) and (b) of this section, the DE for
use in the design of structures, systems, and components must be
determined as follows.''
Comment 8: Two commenters stated that the criteria presented for
establishing the DE for ISFSI and MRS sites at existing NPPs allows for
the use of the existing NPP SSE as one alternative. This alternative is
key to ensuring that significant new probabilistic ground motion
studies are not required at existing NPP sites.
Response: The commenters are correct. The regulatory changes
allowing the licensee flexibility to use the existing SSE for an NPP at
co-located ISFSIs or MRSs means that new studies are not required at
ISFSIs or MRSs co-located with NPPs.
Alternative of Adopting 10 CFR 100.23
Comment 9: One commenter recommended withdrawing the proposed rule
and adopting the option
[[Page 54151]]
of directing new applicants for specific licenses to comply with 10 CFR
100.23 in its entirety, including conforming the DE to the SSE
criteria. The commenter noted that by adopting Sec. 100.23 in its
entirety, there would be no need to make distinctions among locations
of facilities and the rule would incorporate state-of-the-art
improvements in the geosciences and earthquake engineering and would
allow uncertainty to be addressed. The commenter further noted that NRC
had cited its 10 years of experience in reviewing dry cask storage
installation applications as a reasonable basis for allowing an
exceedance probability greater than that applied to a nuclear power
plant, but pointed out that this was 10 years of analytical, not
practical experience. In the commenter's view, this lack of practical
experience, and the fact that a probabilistic analysis is, by its very
nature, risk-informed with respect to uncertainty, means that there
does not seem to be a quantifiable safety basis for any exceedance
margin other than that now applied to seismic analysis for nuclear
power plant proposals. The commenter stated that, absent any definitive
experience, the seismic design criteria for an ISFSI should be no less
protective than that of a nuclear power plant.
Response: The NRC disagrees that new applicants for specific
licenses should comply with Sec. 100.23 in its entirety, including
conforming the DE to the SSE criteria. Adopting the recommendation
would fail to recognize the differences in risk between an NPP and an
ISFSI or MRS facility in seismic design requirements. This is counter
to the Commission policy encouraging development of risk-informed,
performance-based regulations, and the Commission's Performance Goals.
The NRC acknowledges that actual earthquake performance data for
ISFSI facilities are not available and thus that NRC's decision to
allow an exceedance probability greater than that applied to a nuclear
power plant is not based on practical experience. However, NRC has
gained sufficient analytical experience to understand the performance
of these facilities, by reviewing the analyses of these facilities
performed by the licensees, and by performance of independent analyses.
Additionally, experience has been gained in the design and construction
of numerous facilities using the philosophy of a risk-informed approach
described in the standard building codes, similar to the one proposed
in the rule for ISFSIs. The risk-informed approach is also used by the
Department of Energy in designing its facilities for seismic loads with
risks varying from conventional facilities to NPPs. NRC staff's
analyses show that ISFSI storage casks are sufficiently robust, due to
design requirements other than for earthquakes, that there is no
release of radioactivity at an ISFSI site with a DE at a magnitude
equal to the SSE for a NPP. This analytical experience provides a basis
for allowing an exceedance probability greater than that applied to a
nuclear power plant.
Proposed Change to 10 CFR 72.103
Comment 10: With respect to the provision in Sec. 72.103(b) that
sites ``that lie within the range of strong near-field ground motion
from historical earthquakes on large capable faults should be
avoided,'' a commenter stated that the definition of ``range of strong
near-field ground motion'' is not well defined but is often believed to
be about 15 km. The commenter noted that this is a very large set-back
from faults. The commenter argued that the key issue is that the design
ground motion should represent the conditions at the site. If a site is
located close to a large capable fault, then near-fault effects should
be incorporated into the design ground motions rather than excluding
these site locations.
Response: The NRC agrees with the comment. The sentence: ``Sites
that lie within the range of strong near-field ground motion from
historical earthquakes on large capable faults should be avoided.'' has
been removed from Sec. 72.103(b). Section 72.103(f)(2)(iv) requires an
evaluation of the effects of vibratory ground motion that may affect
the design and operation of the proposed ISFSI or MRS. Therefore, near-
fault effects must be included in the development of the ground motion
used in design.
Comment 11: One commenter suggested removing the distinction in
Sec. 72.103 between western U.S. and eastern U.S. The commenter stated
that the characterization of areas of known seismicity east of the
Rocky Mountain Front as including three specific areas is misleading.
The commenter argued that the entire region of the U.S. east of the
Rocky Mountain Front is subject to earthquake occurrence and that one
area should not be treated differently from another for the purpose of
assessing seismic sources. Further, the commenter stated that 10 CFR
part 100, appendix A, does not allow for less stringent alternatives
for any area. Rather, the commenter noted, the fundamental requirements
of that regulation apply uniformly to all regions of the U.S.,
independent of variations in the local rate of seismicity.
Response: In specifying the criteria for determining the DE, the
current part 72 regulations distinguish between the western U.S. and
the eastern U.S. Although the entire eastern U.S. is subject to
earthquake occurrence, the areas east of the Rocky Mountain Front,
except in specific areas of known seismic activity, do not experience
significant seismic activity. Therefore, the use of an appropriate
seismic response anchored at 0.25 g is considered as bounding for the
design. However, for the western U.S. there is significant seismic
activity varying from region to region. Therefore, it is not practical
to use a bounding approach in specifying the DE for those sites.
However, if the applicant chooses the option of performing the PSHA
for a site located in the eastern U.S., as allowed in Sec.
72.103(a)(2), the seismic sources are assessed with the same rigor as
the seismic sources for the PSHA performed for a site located in the
western U.S. (Sec. 72.103(f)). In this case, the regulatory
requirements of assessing the seismic sources for the PSHA method would
apply uniformly to all regions of the U.S., independent of variations
in the local rate of seismicity.
Comment 12: One commenter suggested inserting the word ``sites''
after ``NY'' in the first sentence of Sec. 72.103(a)(1) to be
consistent with language in Sec. 72.102.
Response: The NRC agrees with the commenter's suggestion. The word
``sites'' will be inserted after ``NY'' in the first sentence of Sec.
72.103(a)(1) to be consistent with language in Sec. 72.102. In
addition, other minor editorial changes have been made to this
sentence.
Remove Detailed Guidance From the Regulation
Comment 13: One commenter stated that removing detailed guidance
from the regulation that is related to analyzing non-seismic factors
affecting geologic stability of the site would allow excessive
discretion for the applicant and would result in too much uncertainty
for a safety evaluation. This commenter noted that removing
requirements for specific types of evaluation also removes the
certainty for both the license applicant and the public as to what is
expected during a review. The commenter requested retaining appendix A
of part 100 as requirements for licensing.
Response: See the response to Comment 1.
Comment 14: A commenter questioned NRC's statement explaining that
NRC proposed to remove detailed guidance from the regulation, in part,
because ``specifying geoscience assessments in detail in a regulation
has created difficulties for applicants and
[[Page 54152]]
the NRC by inhibiting needed latitude in judgment [and] [i]t has
inhibited the flexibility needed in applying basic principles to new
situations.'' This commenter asked for an explanation as to how and
when latitude and flexibility in judgment and in applying basic
principles to new situations because geoscience assessments were
specified in detail in a regulation, were inhibited.
Response: The current regulation (Sec. 72.102) requires that for
areas of known potential seismic activity, seismicity will be evaluated
by the techniques of appendix A to part 100. appendix A contains both
requirements and guidance on how to satisfy the requirements. For
example, Section IV, ``Required Investigations,'' of appendix A, states
that investigations are required for vibratory ground motion, surface
faulting, and seismically induced floods and water waves. Appendix A
then provides detailed guidance on what constitutes an acceptable
investigation. Such investigations require considerable latitude in
judgment. This latitude in judgment is needed because of limitations in
data and rapidly evolving state-of-the-art geologic and seismic
analyses.
However, having geoscience assessments detailed and cast in a
regulation has created difficulty for applicants and the NRC in terms
of inhibiting the use of needed latitude in judgment. Also, it has
inhibited flexibility in applying basic principles to new situations
and the use of evolving methods of analyses (for instance,
probabilistic) in the licensing process.
As an example, a prescriptive requirement of applying the capable
fault criteria (see part 100, appendix A, Sec. III(g)) to sites in
California meant conducting investigations and analyses for surface
rupture potential. If a fault does not cause a surface rupture (blind
fault), the fault would not be considered a capable fault under the
appendix A criteria, and thus would not be considered in determining
the DE. This would lead to seismic hazard at a facility which would be
not conservative. This has been demonstrated by the occurrences of the
1989 Loma Prieta, 1992 Petrolia, and 1994 Northridge earthquakes during
which the causative faults did not rupture ground surface. On the other
hand, the young faults, the last movements of which may satisfy the
appendix A criteria for classifying them as capable faults, may not be
capable faults in the true meaning of the criteria because the most
recent displacements on them may be related to non-tectonic natural
phenomena. In this case, use of the appendix A criteria would lead to a
finding of seismic hazard at a facility which would be overly
conservative. Inclusion of detailed criteria or specific numbers in the
regulation prevents a scientific evaluation of methodologies and
approaches that advance with the state of the art, and the rule
eventually becomes a hindrance to the exercise of rational judgement.
Address Uncertainties and Use Probabilistic Methods
Comment 15: A commenter urged revision of Sec. 72.103 to continue
to allow an applicant located in the western U.S. or in areas of known
seismic activity in the eastern U.S., and not co-located with an NPP,
to use a deterministic analysis similar to the analysis specified in
appendix A to 10 CFR part 100, for developing design earthquake ground
motions because a utility may decide to perform seismic hazards
analysis on deterministic bases that are more conservative than the
proposed rule.
Response: In using the deterministic approach for determining a SSE
for a nuclear reactor site embodied in appendix A to 10 CFR part 100,
there have often been differences of opinion and differing
interpretations among experts as to the largest earthquakes to be
considered and ground-motion models to be used. This often makes the
licensing process relatively unstable. Over the past decade, analysis
methods for incorporating these different interpretations have been
developed and used. These ``probabilistic'' methods have been designed
to allow explicit incorporation of different models for zonation,
earthquake size, ground motion, and other parameters. The advantage of
using these probabilistic methods is the ability to incorporate
different models and different data sets and weight them using
judgments as to the validity of the different models and data sets.
This process provides an explicit expression for the uncertainty in the
ground motion estimates and a means of assessing sensitivity to various
input parameters.
Section 72.103 explicitly recognizes that there are inherent
uncertainties in establishing the seismic and geologic design
parameters and requires the use of a probabilistic seismic hazard
methodology capable of propagating uncertainties to address these
uncertainties. The rule further recognizes that the nature of
uncertainty and the appropriate approach to account for it depend
greatly on the tectonic regime and parameters, such as the knowledge of
seismic sources, the existence of historical and recorded data, and the
understanding of tectonics. Therefore, methods other than the
probabilistic methods, such as sensitivity analyses, may be adequate
for some sites to account for uncertainties.
Consistent with Sec. 100.23 for an NPP, Sec. 72.103 does not
allow the use of the deterministic methods in appendix A to 10 CFR part
100, to determine the DE because the deterministic methods do not
account for the uncertainties in the seismic hazard analysis. However,
Sec. 72.103 allows the applicant to use methods other than the
probabilistic methods, such as sensitivity analyses, to account for
uncertainties. Additionally, Sec. 72.103 allows a utility applying for
a specific license for an ISFSI co-located at an NPP, the option of
using the seismic design criteria of the NPP, which may be based on the
deterministic methods of appendix A to 10 CFR part 100.
For these reasons, the NRC declines to amend Sec. 72.103 as
suggested by the commenter. However, a utility applying for a specific
license for an ISFSI co-located at an NPP has the option of using the
seismic design criteria of the NPP.
Comment 16: A commenter stated that the use of the term
``uncertainty'' in the Background section of the proposed rule (67 FR
47746) is ambiguous, and suggested that the term be revised to
``aleatory uncertainty''. The commenter stated that the report
``Recommendations for Probabilistic Seismic Hazard Analysis: Guidance
on Uncertainty and Use of Experts,'' NUREG/CR-6372 (SSHAC),
distinguishes between ``aleatory'' and ``epistemic'' uncertainties. The
deterministic approach can explicitly recognize epistemic uncertainty
just as in the probabilistic approach. The deterministic approach does
not explicitly include all components of aleatory variability. The
commenter noted that sensitivity analyses are generally intended for
addressing epistemic uncertainty, not aleatory variability.
Response: Despite extensive advances in seismic knowledge in recent
years by a large and active community of researchers around the world,
there are still major gaps in the understanding of the mechanisms that
cause earthquakes. These gaps in understanding mean that in any seismic
hazard analysis, either deterministic or probabilistic, there are
inevitably significant uncertainties in the numerical results. These
uncertainties can be classified into two different categories: (1)
epistemic uncertainty which is due to lack of knowledge because the
scientific understanding is imperfect for the
[[Page 54153]]
present, but is of a character that in principle is reducible through
further research; and (2) aleatory uncertainty which is due to the
randomness of seismic events and, in principle, cannot be reduced. As
stated in the SSHAC report, ``The division between the two different
types of uncertainty, epistemic and aleatory, is somewhat arbitrary,
especially at the border between the two. This is because,
conceptually, some of the processes and parameters whose uncertainties
the NRC will characterize here as aleatory (``random'') may be
partially reducible through more elaborate models and/or further
study''. As stated further in the SSHAC report, ``the PSHA that does
not deal appropriately with both the epistemic and the aleatory
uncertainties must be considered inadequate.'' Based on this, the term
``uncertainty'' included in the proposed rule is appropriate.
Revise the Design Earthquake Ground Motion
Comment 17: A commenter stated that performance standards are not
clearly articulated in the proposed rule. The commenter also stated
that before the design standard is lowered, the performance standards
or goals by which the proposed changes were evaluated should first be
identified.
Response: The current regulations in Sec. 72.122(b)(2)(i) require
that the structures, systems, and components of an ISFSI or MRS must be
designed to withstand the effects of natural phenomena, such as
earthquakes, without impairing their capability to perform their
intended design functions. For earthquakes, these requirements are then
supplemented by the Sec. Sec. 72.102 and 72.103 requirements for the
detailed site investigations and consideration of uncertainties in the
prediction of earthquakes. This approach is consistent with the
Commission's philosophy of using risk-informed, performance-based
regulations. In a risk-informed, performance-based approach, the design
of the facility is based on considering the risk (potential for adverse
consequences) due to an earthquake.
Comment 18: One commenter is concerned that lowering the existing
DE may result in a concomitant lowering of the design basis for
locally-sourced tsunamis. The commenter is concerned because the most
likely scenario for release of radiation in a coastal setting would be
damage to an ISFSI or MRS during a major earthquake, followed by
inundation of the facility by a tsunami.
Response: Section 72.103(f)(1) requires consideration of actual or
potential geologic and seismic effects at the proposed site, including
locally-sourced tsunamis. Potential inundation of the facility by a
tsunami is required to be addressed in the design of the facility under
Sec. 72.122(b)(2). Under the amended rule, the tsunami magnitudes
corresponding to the DE would be lower than for a nuclear power plant.
However, an earthquake similar in magnitude to the SSE for an NPP would
not damage an ISFSI or MRS facility, thus no release of radioactivity
would occur even if the facility were inundated by a resulting locally-
sourced tsunami.
Comment 19: A commenter stated that in order to issue a coastal
development permit in California the State or a local government must
make a finding that the proposed ISFSI will minimize risks to life and
property in areas of high geologic hazard, and assure stability and
structural integrity of the proposed coastal development. The commenter
noted that, for the San Onofre Nuclear Generating Station (SONGS)
ISFSI, the required finding was able to be made by the State only
because the applicant proposed a seismic design standard far in excess
of the SSE for the co-located NPP. The commenter indicated that such a
finding may not be possible at future ISFSI sites if the applicant
submits a design standard lower than those required for an NPP. The
commenter stated that the proposed rule change makes approval of
coastal development permits in California for future ISFSIs difficult
at best.
Response: The NRC sees no reason why the rule would make this
finding difficult. The rule ensures adequate protection of public
health and safety in all environs. The close proximity of faults or
populations are considered in the regulations (for example, the dose
requirements contained in Sec. Sec. 72.104(a) and 72.106(b)). Applying
a risk-informed approach to seismic design of ISFSIs takes these
factors into account and the analyses indicate that protection of
public health and safety are adequately addressed.
Proposed Change to 10 CFR 72.212(b)(2)(i)(B)
Comment 20: Two commenters noted that although the proposed change
to 10 CFR 72.212(b)(2)(i)(B) to require that the cask storage pads and
areas be designed to adequately support dynamic loads, as well as
static loads, of the stored casks, may require more analytical effort
than the static load evaluations that some licensees had attempted to
utilize in the past, they find the new requirements to be technically
correct and support the concept that the seismic evaluation should be
conducted using state-of-the-art structural dynamics principles,
including consideration of dynamic loads. One commenter had no
objection to the portion of the proposed rule that would require design
of cask storage pads and areas to adequately account for dynamic loads.
Another commenter stated that requiring this evaluation for storage
pads and areas clearly improves the assurance of safety.
Response: The commenters support the NRC's decision to require
evaluation of dynamic loads for storage cask pads and areas. Further,
general licensees currently consider dynamic loads for evaluating the
casks, pads and areas to meet the cask design bases in the Certificate
of Compliance, as required by 10 CFR 72.212(b)(2)(i)(A); therefore, the
rule change will not actually impose a new burden on the general
licensees.
Related Regulatory Guide
Comment 21: A commenter stated that Draft Regulatory Guide DG-3021
``is short on firm standards'' because, although it recommends a DE at
a MAPE of 5E-4, it also allows an applicant to demonstrate that the use
of a higher probability of exceedance value would not impose any undue
radiological risk to public health and safety. Thus, the draft
guidance, in the commenter's view, ``leaves open the possibility of an
even lower standard for seismic sites.'' Another commenter defends the
guidance that an applicant could propose a higher probability of
exceedance value as being an exemption to what the commenter sees as
the norm being established in DG-3021.
Response: Section 72.103(f)(2)(i) of the rule requires that an
applicant include a determination of the DE for the site, considering
the results of the investigations required by paragraph (f)(1) and
addressing uncertainties through an appropriate analysis, such as a
PSHA or suitable sensitivity analyses. Regulatory Guide 3.73 (formerly
DG-3021) states that a mean annual probability of exceeding the DE of
5E-4 is recommended to be used in conjunction with the PSHA for
determining the DE. As the commenter notes, the draft guidance also
indicated that ``[t]he use of a higher reference probability will be
reviewed and accepted on a case-by-case basis.'' This statement was
made in recognition of the fact that a regulatory guide does not
establish legally-binding requirements. An alternative reference
probability would not be an exemption from a requirement, but would be
an alternative proposal which would need to be demonstrated to be
acceptable. Thus, it is conceivable that an applicant could propose a
higher MAPE value that the NRC staff would then have to consider.
Although this is necessarily
[[Page 54154]]
the case for recommendations suggested in guidance documents, the NRC
did not mean to imply that it viewed an applicant's ability to make the
necessary safety case for a higher MAPE as being a likely prospect. To
avoid any such implication, that sentence has been removed from the
final guidance.
Comment 22: One commenter stated that a DE at a MAPE of 5E-4 (2,000
year return period) is not defensible. The commenter said that there
are numerous standards that already use a DE at a MAPE of 4E-4 (2,500
year return period), including DOE Standard 1020-2000. The commenter
noted that DOE's standard is inextricably tied to meeting performance
and risk goals. Further, the commenter indicated that certain
buildings, such as hospitals, must meet a DE at a MAPE of 4E-4 (2,500
year return period), as must interstate bridges in the State of Utah.
The commenter stated that, at a minimum, a standard lower than these
cannot be adopted.
Response: The NRC disagrees with the commenter that the proposed
standard for the DE at a MAPE of 5E-4 (2,000 year return period) is
lower than the DOE Standard DOE-STD-1020-2002, or the other standards,
such as the International Building Code (IBC-2000 Code).
According to the DOE Standard DOE-STD-1020-2002, ISFSIs can be
classified as Performance Category 3 (PC-3) facilities. For PC-3
facilities, the seismic design forces for the DE are initially
determined at 90 percent of the DE at a MAPE of 4E-4 (2,500 years
return period). This brings the DE levels to approximately a MAPE of
5E-4 (2,000 year return period), specified in the earlier DOE 1020
standard, DOE-STD-1020-94. The Foreword of the DOE-STD-1020-2002
explains the change in the return period as follows:
``It is not the intent of this revision to alter the methodology
for evaluating PC-3 facilities, nor to increase the performance goal of
PC-3 facilities, by increasing return period for the PC-3 from a 2,000-
year earthquake to a 2,500-year earthquake. Rather, the intention is
more for convenience to provide a linkage from the NEHRP maps and DOE
Standards.''
Therefore, use of the reference probability of 5E-4/yr (2,000 year
return period), for the ISFSI or MRS facility DE, would be consistent
with that used in the DOE Standard DOE-STD-1020, for similar type
facilities.
For the IBC-2000 Code, the commenter is incorrectly comparing the
ISFSI or MRS DE at a MAPE of 5E-4 (2,000 year return period), with the
Maximum Considered Earthquake (MCE) at a MAPE of 4E-4 (2,500 year
return period). The DE, according to the IBC-2000 Code, is two-thirds
of the MCE, which is equivalent to a DE at a MAPE of 1.1E-3 (909 year
return period) earthquake in the western United States, and a DE at a
MAPE of 7E-4 (1,430 year return period) in the eastern United States.
Thus, the DE for the ISFSI or MRS facility included in DG-3021 at a
MAPE of 5E-4 is greater than the IBC Code DE design level.
The NRC agrees that hospital building structures and bridges having
critical national defense functions are designed for the DE at a MAPE
of 4E-4 (2,500 year return period). These structures are generally
occupied by a significant number of people. Therefore, these structures
are designed for loads greater than those for traditional buildings to
limit building deformations, and to minimize human losses due to an
earthquake. The ISFSI or MRS facility, on the other hand, has a
relatively small number of people occupying the Canister Transfer
Building at any one time.
Comment 23: A commenter requested that the regulatory guide specify
a DE at a MAPE of 1E-4 (10,000 year return period), consistent with the
requirement for NPPs. This commenter believes that meeting NPP
standards would be easier at an ISFSI or MRS due to the relative
simplicity of construction and robust character of the structures as
compared to an NPP.
Response: The NRC disagrees with the commenter and believes that
the proposed DE at a MAPE of 5E-4 (2,000 year return period) for an
ISFSI or MRS facility is adequate for protecting public health and
safety. The seismically induced risk from the operation of an ISFSI or
MRS is less than from the operation of an NPP, and based on the review
of the current seismic design practice, the proposed DE design level is
reasonable and consistent with the NRC's policy of risk-informed,
performance-based regulations. Details of the NRC's review for the
proposed DE level are provided in the report, ``Selection of Design
Earthquake Ground Motion Reference Probability''. This report may be
accessed through the NRC's Public Electronic Reading Room on the
Internet at http://www.nrc.gov/reading-rm/adams.html. If you do not
have access to ADAMS or if there are problems in accessing the
documents located in ADAMS, contact the NRC's PDR reference staff at 1-
800-397-4209, 301-415-4737, or by email to pdr@nrc.gov. The NRC agrees with the commenter that the cask structure is simple
in construction and robust in character resulting from the design
considerations other than earthquake effects. Earthquake loads and the
DE level would not govern the cask design. However, this is not the
case in the design and stability evaluation of other ISFSI or MRS
facility structures, systems, and components, such as the concrete pad,
foundation, and the canister transfer building. Designs of these
structures, systems, and components depend on the DE level. Further,
because of the inherent safety margins in the design criteria in NUREG-
1536 and NUREG-1567, the structures, systems, and components designed
for a DE at a MAPE of 5E-4 (2,000 year return period) would be able to
withstand a DE at a MAPE of 1E-4 (10,000 year return period consistent
with the NPP requirements) without impairing the ability to meet the
Part 72 dose limits for protecting public health and safety. Therefore,
it is an unnecessary burden on the applicant to require the ISFSI or
MRS facility to design for a DE at a level consistent with NPP
requirements.
Comment 24: Two commenters stated that the seismic design standard
(MAPE of 5E-4 (2,000 year return period)) is less protective than the
seismic standard for municipal solid waste landfills in California
(maximum credible earthquake (MCE) of 4E-4 (2,500 year return period)),
and the International Building Code (MCE of 4E-4 (2,500 year return
period)), both of which are more stringent than the proposed rule. One
commenter is concerned that a DE at a MAPE of 5E-4 (2,000 year return
period) may not provide an adequate margin of safety to protect the
public.
However, two other commenters stated that the rigor of the seismic
evaluation criteria and the conservatism of the seismic design
requirements significantly exceed those in modern conventional building
codes. One of the commenters stated that the annual probability of
unacceptable seismic performance for a dry cask ISFSI designed to a DE
at a MAPE of 5E-4 (2,000 year return period) will be substantially less
than that of an essential or hazardous facility designed to the modern
conventional building code for which the DE was established at 67
percent of the MCE of 4E-4. Another commenter stated that the level of
safety for a dry cask storage facility designed to a DE at a MAPE of
5E-4 (2,000 year return period) provides at least twice the level of
safety attained by facilities designed under the International Building
Code.
Response: The NRC disagrees with the commenters that the seismic
design standard (MAPE of 5E-4) is less protective than the seismic
standard for
[[Page 54155]]
municipal solid waste landfills in California (Code of Regulations
Section 66264.25(b), and the International Building Code--2000 (IBC-
2000). The California standard requires the municipal waste landfills
to be designed to withstand the maximum credible earthquake (MAPE of
4E-4) of the IBC-2000 without decreasing the level of public health and
environmental protection. The cask and the cask transfer building at an
ISFSI or MRS facility, designed to a DE at a MAPE of 5E-4, has the
capacity to withstand earthquakes of greater magnitude than the one
associated with the MAPE of 4E-4. This is because of the conservatism
in the seismic evaluation criteria and of NRC's NUREG-1536 and NUREG-
1567, which significantly exceed those in modern conventional building
codes. Additionally, the risk of the ISFSI or MRS facility to public
health and safety is lower than the risk for hazardous waste and
municipal solid waste landfills because the spent nuclear fuel is
contained within a sealed steel cask in an isolated facility away from
the public, with a controlled boundary at a minimum distance of 100 m.
Landfills, on the other hand, may be open and in close proximity to
public areas.
Comment 25: Three commenters stated that the proposed rule provided
no basis or quantitative analysis to justify lowering the DE to any
particular value. One of these commenters indicated that absent any
quantitative evidence justifying a particular value, the conservative,
precautionary approach of requiring ISFSIs and MRSs to meet the same
design standard as a nuclear power plant is most appropriate. One of
these commenters noted that the adequacy of the MAPE should be
addressed with respect to the change in the DE. The commenter stated
that this could be addressed by using the higher proposed MAPE versus
what is currently required and then determining if the change in the
level of risk of a release is significant or not.
Response: The DE level proposed in the draft regulatory guide was
selected based on the fact that the ISFSI or MRS risk is lower than
that of an NPP and on the fact that this level is consistent with the
hazard levels used in the nuclear industry for similar facilities.
Details of the NRC's analyses for establishing the DE level are
provided in the report, ``Selection of Design Earthquake Ground Motion
Reference Probability''. This report may be accessed through the NRC's
Public Electronic Reading Room on the Internet at http://www.nrc.gov/reading-rm/adams.html.
If you do not have access to ADAMS or if there
are problems in accessing the documents located in ADAMS, contact the
NRC's PDR reference staff at 1-800-397-4209, 301-415-4737, or by email
to pdr@nrc.gov. Comment 26: Two commenters strongly endorsed the proposal to lower
the DE. The commenters stated that the DE provided in the draft
regulatory guide at a MAPE of 5E-4 (2,000 year return period) provides
a level of relief in establishing the DE that is completely consistent
with the risk-informed regulation policy and is an excellent example of
the application of the policy. One commenter stated that the philosophy
of applying a graded approach to seismic design requirements for
facilities of differing risks has been in existence for more than 30
years. The commenter described DOE's approach for seismic design
requirements for DOE facilities, which span a range of potential risks.
The commenter went on to state that based on the amount of radioactive
material stored in a large dry cask ISFSI, the resulting classification
using the DOE approach would result in a design standard with a MAPE of
5E-4. The commenter stated that considering the minor radiological
consequences from a single canister failure and a lack of a credible
mechanism to cause such a failure from a seismic event would suggest
that this design criteria level is more than adequately conservative
for a dry cask ISFSI.
Response: The commenters support the NRC's recommendation of the
seismic design earthquake level to a MAPE of 5E-4 (2,000 year return
period).
Finding of No Significant Environmental Impact: Availability
Comment 27: Three commenters challenged the assertion that the NRC
has considerable experience in licensing dry cask storage systems and
analyzing cask behavior. One commenter noted that the NRC has licensed
only four ISFSIs in the western U.S., the most seismically active part
of the country, and none as close to major plate-boundary faults as the
three planned for coastal California. The commenters also said that
analytical experience in licensing does not equate with practical
experience. One commenter stated that this will only be achieved when
an ISFSI experiences strong ground motions as a result of a major
earthquake. As a result, the commenter believes that neither the
specific nor general licenses issued have been tested.
Response: As discussed in the NRC response to Comment 4, cask
stability can be evaluated with adequate reliability by using non-
linear dynamic analyses because the concept of free-standing structures
is not a new one. One does not need to test all structures prior to
using them, provided structures are simple and can be reliably
analyzed.
Regulatory Analysis
Comment 28: A commenter noted that the proposed changes impose no
new burdens on establishing the DE for an ISFSI over the current
requirements in 10 CFR part 72.
Response: The NRC's analysis actually indicates that there would be
an overall reduction in the total burden placed on licensees from these
changes. The estimate of values and impacts to a specific-license
applicant indicates additional costs of $100,000 for addressing
uncertainties in seismic hazard analysis. In some cases, ISFSI
specific-license applicants have sought exemptions from the design
requirements contained in Sec. 72.102, considering site
characteristics and other factors. The rule would reduce or eliminate
the need for these exemption requests by reducing the DE level for
certain structures, systems, and components, resulting in a savings of
$150,000 per license applicant. Further, no structures, systems, and
components would be required to be designed to withstand a DE at a MAPE
of 1E-4 (equivalent to the SSE of an NPP), resulting in lower
analytical and certain capital costs. The overall effect of the rule
would be a cost savings to new specific-license applicants. However,
the amount of these savings is highly site-specific, depending on site
characteristics and the specified DE level.
Finally, the rule will change Sec. 72.212(b)(2)(i)(B) to require
written evaluations, prior to use, establishing that cask storage pads
and areas have been evaluated for the static and dynamic loads of the
stored casks. There are no additional costs associated with evaluating
cask pads and areas for dynamic loads because general licensees are
already required to consider dynamic loads to meet the cask design
basis of the Certificate of Compliance under Sec. 72.212(b)(i)(A).
VII. Summary of Final Revisions
This final rule will make the following changes to 10 CFR part 72:
Section 72.9 Information collection requirements: OMB approval
In Sec. 72.9, the list of sections where approved information
collection requirements appear is amended to add Sec. 72.103.
[[Page 54156]]
Section 72.102 Geological and seismological characteristics (Current
Heading)
Section 72.102 Geological and seismological characteristics for
applications before October 16, 2003 and applications for other than
dry cask modes of storage (New Heading)
The heading of Sec. 72.102 is revised because Sec. 72.103 is
added for ISFSI or MRS applications after the effective date of the
rule. Section 72.103 will only apply to dry cask modes of storage.
Therefore, the heading of Sec. 72.102 is being modified to show the
revised applicability of this section. The requirements of Sec. 72.102
will continue to apply for an ISFSI or MRS using wet modes of storage
or dry modes of storage that do not use casks.
The NRC does not intend for existing part 72 licensees to re-
evaluate the geological and seismological characteristics for siting
and design using the revised criteria in the changes to the
regulations. These existing facilities are considered safe because the
criteria used in their evaluation have been determined to be safe for
NPP licensing, and the seismically induced risk of an ISFSI or MRS is
significantly lower than that of an NPP. The change leaves the current
Sec. 72.102 in place to preserve the licensing bases of present
ISFSIs.
Section 72.103 Geological and seismological characteristics for
applications for dry cask modes of storage on or after October 16, 2003
The trend towards dry cask storage has resulted in the need for
applicants for new licenses to request exemptions from Sec.
72.102(f)(1), which requires that for sites evaluated under the
criteria of Appendix A to Part 100, the DE must be equivalent to the
SSE for an NPP. By making Sec. 72.102 applicable only to existing
ISFSIs and by providing a new Sec. 72.103, the revised rule is
intended to preclude the need for exemption requests from new specific-
license applicants.
The new requirements in Sec. 72.103 parallel the requirements in
Sec. 72.102. However, new specific-license applicants for sites
located in either the western U.S. or in the eastern U.S. in areas of
known seismic activity, and not co-located with an NPP, for dry cask
storage applications, on or after the effective date of this rule, will
be required to address the uncertainties in seismic hazard analysis by
using a PSHA or sensitivity analyses instead of using the deterministic
methods of Appendix A to Part 100 without sensitivity analyses.
Applicants located in either the western U.S. or in areas of known
seismic activity in the eastern U.S., and co-located with an NPP, have
the option of using the PSHA methodology or suitable sensitivity
analyses for determining the DE, or using the existing design criteria
for the NPP. This change to require an understanding of the
uncertainties in the determination of the DE will make the regulations
compatible with 10 CFR 100.23 for NPPs and will allow the geological
and seismological criteria for ISFSI or MRS dry cask storage facilities
to be risk-informed.
New Sec. 72.103(a)(1) provides that sites located in eastern U.S.
and not in areas of known seismic activity, will be acceptable if the
results from onsite foundation and geological investigation, literature
review, and regional geological reconnaissance show no unstable
geological characteristics, soil stability problems, or potential for
vibratory ground motion at the site in excess of an appropriate
response spectrum anchored at 0.2 g. Section 72.103(a)(1) will parallel
the requirements currently included in Sec. 72.102(a)(1).
New Sec. 72.103(a)(2) provides that applicants conducting
evaluations in accordance with Sec. 72.103(a)(1) may use a
standardized DE described by an appropriate response spectrum anchored
at 0.25 g. These requirements parallel the requirements currently
included in Sec. 72.102(a)(2). Section 72.102(a)(2) provides an
alternative to determine a site-specific DE using the criteria and
level of investigations required by Appendix A to Part 100. New Sec.
72.103(a)(2) also provides, as an alternative, that a site-specific DE
may be determined by using the criteria and level of investigations in
new Sec. 72.103(f). Section 72.103(f) is a new provision that requires
certain new ISFSI or MRS license applicants to address uncertainties in
seismic hazard analysis by using appropriate analyses, such as a PSHA
or suitable sensitivity analyses, in determining the DE instead of the
current deterministic approach in Appendix A to Part 100.
New Sec. 72.103(a)(2) also provides that if an ISFSI or MRS is
located at an NPP site, the existing geological and seismological
design criteria for the NPP may be used instead of PSHA techniques or
suitable sensitivity analyses because the risk due to a seismic event
at an ISFSI or MRS is less than that of an NPP. If the existing design
criteria for the NPP is used and the site has multiple NPPs, then the
criteria for the most recent NPP must be used to ensure that the
seismic design criteria used is based on the latest seismic hazard
information at the site.
New Sec. 72.103(b) provides that applicants for licenses for sites
located in either the western U.S. or in the eastern U.S. in areas of
known seismic activity, must investigate the geological, seismological,
and engineering characteristics of the site using the PSHA techniques
or suitable sensitivity analyses of new Sec. 72.103(f). If an ISFSI or
MRS is located at an NPP site, the existing geological and
seismological design criteria for the NPP may be used instead of PSHA
techniques or suitable sensitivity analyses because the risk due to a
seismic event at an ISFSI or MRS is less than that of an NPP. If the
existing design criteria for the NPP is used and the site has multiple
NPPs, then the criteria for the most recent NPP must be used to ensure
that the seismic design criteria used is based on the latest seismic
hazard information at the site.
New Sec. 72.103(c) is identical to Sec. 72.102(c). Section
72.103(c) requires that sites, other than bedrock sites, must be
evaluated for the liquefaction potential or other soil instability due
to vibratory ground motion. This is to ensure that an ISFSI or MRS will
be adequately supported on a stable foundation during a seismic event.
New Sec. 72.103(d) is identical to Sec. 72.102(d). Section
72.103(d) requires that site specific investigation and laboratory
analysis must show that soil conditions are adequate for the proposed
foundation loading. This is to ensure that an ISFSI or MRS will be
adequately supported on a stable foundation during a seismic event.
New Sec. 72.103(e) is identical to Sec. 72.102(e). Section
72.103(e) requires that in an evaluation of alternative sites, those
which require a minimum of engineered provisions to correct site
deficiencies are preferred, and that sites with unstable geologic
characteristics should be avoided. This is to ensure that sites with
minimum deficiencies are selected and that an ISFSI or MRS will be
adequately supported on a stable foundation during a seismic event.
New Sec. 72.103(f) describes the steps required for seismic hazard
analysis to determine the DE for use in the design of structures,
systems, and components of an ISFSI or MRS. The scope of site
investigations to determine the geological, seismological, and
engineering characteristics of a site and its environs is similar to
Sec. 100.23 requirements. Unlike Sec. 72.102(f), which requires the
use of the deterministic method of Appendix A to Part 100, new Sec.
72.103(f) requires evaluating uncertainty in seismic hazard analysis
[[Page 54157]]
by using a probabilistic method, such as the PSHA, or suitable
sensitivity analyses, similar to Sec. 100.23 requirements for an NPP.
New Sec. 72.103(f)(1) requires that the geological, seismological,
and engineering characteristics of a site and its environs must be
investigated in sufficient scope and detail to permit an adequate
evaluation of the proposed site and to determine the DE. These
requirements track existing requirements in Sec. 100.23(c).
New Sec. Sec. 72.103(f)(2)(i) through (iv) specify criteria for
determining the DE for the site, the potential for surface tectonic and
nontectonic deformations, the design basis for seismically induced
floods and water waves, and other design conditions. In particular,
Sec. 72.103(f)(2)(i) provides that a specific-license applicant must
address uncertainties in seismic hazard analysis by using appropriate
analyses, such as a PSHA or suitable sensitivity analyses, for
determining the DE. Sections 72.103(f)(2)(ii) through (iv) track the
corresponding requirements in Sec. 100.23(d).
Finally, the new Sec. 72.103(f)(3) provides that regardless of the
results of the investigations anywhere in the continental U.S., the DE
must have a value for the horizontal ground motion of no less than 0.10
g with the appropriate response spectrum. This provision is identical
to the requirement currently included in Sec. 72.102(f)(2).
Section 72.212 Conditions of general license issued under Sec. 72.210
Section 72.212(b)(2)(i)(B) is revised to require general licensees
to address the dynamic loads of the stored casks in addition to the
static loads. The requirements are changed because during a seismic
event the cask experiences dynamic inertia loads in addition to the
static loads, which are supported by the concrete pad. The dynamic
loads depend on the interaction of the casks, the pad, and the
foundation. Consideration of the dynamic loads, in addition to the
static loads, of the stored casks will ensure that the pad would
perform satisfactorily during a seismic event.
The new paragraph also requires consideration of potential
amplification of earthquakes through soil-structure interaction, and
soil liquefaction potential or other soil instability due to vibratory
ground motion. Depending on the properties of soil and structures, the
free-field earthquake acceleration input loads may be amplified at the
top of the storage pad. These amplified acceleration input values must
be bound by the design bases seismic acceleration values for the cask,
specified in the Certificate of Compliance. Liquefaction of the soil
and instability during a vibratory motion due to an earthquake may
affect the cask stability, and thus must be addressed.
The changes to Sec. 72.212 are intended to require that general
licensees perform appropriate load evaluations of cask storage pads and
areas to ensure that casks are not placed in an unanalyzed condition.
Similar requirements currently exist in Sec. 72.102(c) for an ISFSI
specific license and are now in Sec. 72.103(c).
VIII. Criminal Penalties
For the purpose of Section 223 of the Atomic Energy Act (AEA), the
Commission is issuing this final rule to amend 10 CFR Part 72 under one
or more of sections 161b, 161i, or 161o of the AEA. Willful violations
of the rule will be subject to criminal enforcement.
IX. Agreement State Compatibility
Under the ``Policy Statement on Adequacy and Compatibility of
Agreement State Programs'' approved by the Commission on June 30, 1997,
and published in the Federal Register on September 3, 1997 (62 FR
46517), this rule is classified as Compatibility Category ``NRC.''
Compatibility is not required for Category ``NRC'' regulations. The NRC
program elements in this category are those that relate directly to
areas of regulation reserved to the NRC by the AEA of 1954, as amended
(AEA), or the provisions of Title 10 of the Code of Federal
Regulations. Although an Agreement State may not adopt program elements
reserved to the NRC, it may wish to inform its licensees of certain
requirements via a mechanism that is consistent with the particular
State's administrative procedure laws, but does not confer regulatory
authority on the State.
X. Voluntary Consensus Standards
The National Technology Transfer Act of 1995 (Pub. L. 104-113)
requires that Federal agencies use technical standards that are
developed or adopted by voluntary consensus standards bodies unless the
use of such a standard is inconsistent with applicable law or otherwise
impractical. In this final rule, the NRC is presenting amendments to
its regulations in 10 CFR part 72 for the geological and seismological
criteria of a dry cask independent spent fuel storage facility to make
them commensurate with the risk of the facility. This action does not
constitute the establishment of a standard that establishes generally
applicable requirements.
XI. Finding of No Significant Environmental Impact: Availability
The Commission has determined under the National Environmental
Policy Act of 1969, as amended, and the Commission's regulations in
Subpart A of 10 CFR part 51, that this rule is not a major Federal
action significantly affecting the quality of the human environment and
therefore an environmental impact statement is not required.
The Commission concluded, based on an environmental assessment,
that no significant environmental impact would result from this
rulemaking. In comparison with an NPP, an operating ISFSI or MRS is a
passive facility in which the primary activities are waste receipt,
handling, and storage. An ISFSI or MRS does not have the variety and
complexity of active systems necessary to support an operating NPP.
After the spent fuel is in place, an ISFSI or MRS is essentially a
static operation and, during normal operations, the conditions required
for the release and dispersal of significant quantities of radioactive
materials are not present. There are no high temperatures or pressures
present during normal operations or under design basis accident
conditions to cause the release and dispersal of radioactive materials.
This is primarily due to the low heat generation rate of spent fuel
after it has decayed for more than one year before storage in an ISFSI
or MRS and the low inventory of volatile radioactive materials readily
available for release to the environs. The long-lived nuclides present
in spent fuel are tightly bound in the fuel materials and are not
readily dispersible. The short-lived volatile nuclides, such as I-131,
are no longer present in aged spent fuel stored at an ISFSI or MRS.
Furthermore, even if the short-lived nuclides were present during an
event of a fuel assembly rupture, the canister surrounding the fuel
assemblies would confine these nuclides.
The standards in part 72 Subparts E ``Siting Evaluation Factors,''
and F ``General Design Criteria,'' ensure that the dry cask storage
designs are very rugged and robust. The casks must maintain structural
integrity during a variety of postulated non-seismic events, including
cask drops, tip-over, and wind driven missile impacts. These non-
seismic events challenge cask integrity significantly more than seismic
events. Therefore, the casks have substantial design margins to
withstand
[[Page 54158]]
forces from a seismic event greater than the design earthquake.
Hence, the seismically induced radiological risk associated with an
ISFSI or MRS is less than the risk associated with an NPP.
The determination of the environmental assessment is that there
will be no significant environmental impact due to the rule changes
because the same level of safety would be maintained by the new
requirements, taking into account the lesser risk from an ISFSI or MRS.
The NRC requested public comments on the environmental assessment for
this rule.
XII. Paperwork Reduction Act Statement
This final rule amends information collection requirements that are
subject to the Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq).
These requirements were approved by the Office of Management and
Budget, approval number 3150-0132.
Because the rule will reduce existing information collection
requirements, the public burden for these information collections is
expected to be decreased by 55 hours per licensee. This reduction
includes the time required for reviewing instructions, searching
existing data sources, gathering and maintaining the data needed and
completing and reviewing the information collection. Send comments on
any aspect of these information collections, including suggestions for
further reducing the burden, to the Records Management Branch (T-6 E6),
U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by
Internet electronic mail at infocollects@nrc.gov; and to the Desk
Officer, Office of Information and Regulatory Affairs, NEOB-10202,
(3150-0132), Office of Management and Budget, Washington, DC 20503.
Public Protection Notification
The NRC may not conduct or sponsor, and a person is not required to
respond to a request for information or an information collection
requirement unless the requesting document displays a currently valid
OMB control number.
XIII. Regulatory Analysis
The Commission has prepared a Regulatory Analysis (RA) entitled:
``Regulatory Analysis of Geological and Seismological Characteristics
for Design of Dry Cask Independent Spent Fuel Storage Installations.''
The RA examines the costs and benefits of the alternatives considered
by the Commission. The RA may be accessed through the NRC's Public
Electronic Reading Room on the Internet at http://www.nrc.gov/reading-rm/adams.html.
If you do not have access to ADAMS or if there are
problems in accessing the documents located in ADAMS, contact the NRC's
PDR reference staff at 1-800-397-4209, 301-415-4737, or by email to
pdr@nrc.gov.
XIV. Regulatory Flexibility Certification
In accordance with the Regulatory Flexibility Act of 1980 (5 U.S.C.
605(b)), the Commission certifies that this rule does not have a
significant economic impact on a substantial number of small entities.
This rule affects applicants for a Part 72 specific license, and
general licensees on or after the effective date of the rule for an
ISFSI or MRS. These companies do not generally fall within the scope of
the definition of ``small entities'' set forth in the Regulatory
Flexibility Act or the Small Business Size Standards set out in
regulations issued by the Small Business Administration at 13 CFR Part
121.
XV. Backfit Analysis
The NRC has determined that the backfit rule, 72.62, does not apply
to the changes in Sec. Sec. 72.9, 72.102, and 72.103 because they do
not involve any provisions that would impose backfits as defined in the
backfit rule. Therefore, a backfit analysis is not required for these
provisions.
Section 72.212(b)(2)(i)(B) currently requires evaluations of static
loads of the stored casks for design of the cask storage pads and areas
(foundation). The revision to this section will require general
licensees also to address the dynamic loads of the stored casks. During
a seismic event, the cask storage pads and areas experience dynamic
loads in addition to static loads. The dynamic loads depend on the
interaction of the casks, cask storage pads, and areas. Consideration
of the dynamic loads of the stored casks, in addition to the static
loads, for the design of the cask storage pads and areas will ensure
that the cask storage pads and areas will perform satisfactorily in the
event of an earthquake.
The revision will also require consideration of potential
amplification of earthquakes through soil-structure interaction, and
soil liquefaction potential or other soil instability due to vibratory
ground motion. Depending on the properties of soil and structures, the
free-field earthquake acceleration input loads may be amplified at the
top of the storage pad. These amplified acceleration input values must
be bound by the design bases seismic acceleration values for the cask
specified in the Certificate of Compliance. The soil liquefaction and
instability during a vibratory motion due to an earthquake may affect
the cask stability.
The changes to Sec. 72.212(b)(2)(i)(B) will impact procedures
required to operate an ISFSI and, therefore, implicate the backfit
rule. The changes will require that general licensees perform
appropriate analyses to assure that the cask seismic design bases bound
the specific site seismic conditions, and that casks are not placed in
an unanalyzed condition. Therefore, these changes are necessary to
assure adequate protection to occupational or public health and safety.
Although the Commission is imposing this backfit because it is
necessary to assure adequate protection to occupational or public
health and safety, the changes to Sec. 72.212 will not actually impose
new burden on the general licensees because they currently need to
consider dynamic loads to meet the requirements in Sec.
72.212(b)(2)(i)(A). Section 72.212(b)(2)(i)(A) requires general
licensees to perform written evaluations to meet conditions set forth
in the cask Certificate of Compliance. These Certificates of Compliance
require that dynamic loads, such as seismic and tornado loads, be
evaluated to meet the cask design bases. Because the general licensees
currently evaluate dynamic loads for evaluating the casks, pads and
areas, the changes to Sec. 72.212(b)(2)(i)(B) will not actually
require any general licensees presently operating an ISFSI to re-
perform any written evaluations previously undertaken.
XVI. Small Business Regulatory Enforcement Fairness Act
In accordance with the Small Business Regulatory Enforcement
Fairness Act of 1996, the NRC has determined that this action is not a
major rule and has verified this determination with the Office of
Information and Regulatory Affairs of OMB.
List of Subjects In 10 CFR Part 72
Administrative practice and procedure, Criminal penalties, Manpower
training programs, Nuclear materials, Occupational safety and health,
Penalties, Radiation protection, Reporting and recordkeeping
requirements, Security measures, Spent fuel, Whistleblowing.
0
For the reasons set out in the preamble and under the authority of the
Atomic Energy Act of 1954, as amended; the Energy Reorganization Act of
1974, as amended; and 5 U.S.C. 552 and 553; the
[[Page 54159]]
NRC is adopting the following amendments to 10 CFR part 72.
PART 72--LICENSING REQUIREMENTS FOR THE INDEPENDENT STORAGE OF
SPENT NUCLEAR FUEL, HIGH-LEVEL RADIOACTIVE WASTE, AND REACTOR-
RELATED GREATER THAN CLASS C WASTE
0
1. The authority citation for Part 72 continues to read as follows:
Authority: Secs. 51, 53, 57, 62, 63, 65, 69, 81, 161, 182, 183,
184, 186, 187, 189, 68 Stat. 929, 930, 932, 933, 934, 935, 948, 953,
954, 955, as amended, sec. 234, 83 Stat. 444, as amended (42 U.S.C.
2071, 2073, 2077, 2092, 2093, 2095, 2099, 2111, 2201, 2232, 2233,
2234, 2236, 2237, 2238, 2282); sec. 274, Pub. L. 86-373, 73 Stat.
688, as amended (42 U.S.C. 2021); sec. 201, as amended, 202, 206, 88
Stat. 1242, as amended, 1244, 1246 (42 U.S.C. 5841, 5842, 5846);
Pub. L. 95-601, sec. 10, 92 Stat. 2951 as amended by Pub. L. 102-
486, sec. 7902, 106 Stat. 3123 (42 U.S.C. 5851); sec. 102, Pub. L.
91-190, 83 Stat. 853 (42 U.S.C. 4332); secs. 131, 132, 133, 135,
137, 141, Pub. L. 97-425, 96 Stat. 2229, 2230, 2232, 2241, sec. 148,
Pub. L. 100-203, 101 Stat. 1330-235 (42 U.S.C. 10151, 10152, 10153,
10155, 10157, 10161, 10168).
Section 72.44(g) also issued under secs. 142(b) and 148(c), (d),
Pub. L. 100-203, 101 Stat. 1330-232, 1330-236 (42 U.S.C. 10162(b),
10168(c), (d)). Section 72.46 also issued under sec. 189, 68 Stat.
955 (42 U.S.C. 2239); sec. 134, Pub. L. 97-425, 96 Stat. 2230 (42
U.S.C. 10154). Section 72.96(d) also issued under sec. 145(g), Pub.
L. 100-203, 101 Stat. 1330-235 (42 U.S.C. 10165(g)). Subpart J also
issued under secs. 2(2), 2(15), 2(19), 117(a), 141(h), Pub. L. 97-
425, 96 Stat. 2202, 2203, 2204, 2222, 2224, (42 U.S.C. 10101,
10137(a), 10161(h)). Subparts K and L are also issued under sec.
133, 98 Stat. 2230 (42 U.S.C. 10153) and sec. 218(a), 96 Stat. 2252
(42 U.S.C. 10198).
0
2. In Sec. 72.9, paragraph (b) is revised to read as follows:
Sec. 72.9 Information collection requirements: OMB approval.
* * * * *
(b) The approved information collection requirements contained in
this part appear in Sec. Sec. 72.7, 72.11, 72.16, 72.22 through 72.34,
72.42, 72.44, 72.48 through 72.56, 72.62, 72.70, through 72.82, 72.90,
72.92, 72.94, 72.98, 72.100, 72.102, 72.103, 72.104, 72.108, 72.120,
72.126, 72.140 through 72.176, 72.180 through 72.186, 72.192, 72.206,
72.212, 72.216, 72.218, 72.230, 72.232, 72.234, 72.236, 72.240, 72.242,
72.244, 72.248.
0
3. The heading of Sec. 72.102 is revised to read as follows:
Sec. 72.102 Geological and seismological characteristics for
applications before October 16, 2003 and applications for other than
dry cask modes of storage.
* * * * *
0
4. A new Sec. 72.103 is added to read as follows:
Sec. 72.103 Geological and seismological characteristics for
applications for dry cask modes of storage on or after October 16,
2003.
(a)(1) East of the Rocky Mountain Front (east of approximately
104[deg] west longitude), except in areas of known seismic activity
including but not limited to the regions around New Madrid, MO;
Charleston, SC; and Attica, NY; sites will be acceptable if the results
from onsite foundation and geological investigation, literature review,
and regional geological reconnaissance show no unstable geological
characteristics, soil stability problems, or potential for vibratory
ground motion at the site in excess of an appropriate response spectrum
anchored at 0.2 g.
(2) For those sites that have been evaluated under paragraph (a)(1)
of this section that are east of the Rocky Mountain Front, and that are
not in areas of known seismic activity, a standardized design
earthquake ground motion (DE) described by an appropriate response
spectrum anchored at 0.25 g may be used. Alternatively, a site-specific
DE may be determined by using the criteria and level of investigations
required by paragraph (f) of this section. For a site with a co-located
nuclear power plant (NPP), the existing geological and seismological
design criteria for the NPP may be used. If the existing design
criteria for the NPP is used and the site has multiple NPPs, then the
criteria for the most recent NPP must be used.
(b) West of the Rocky Mountain Front (west of approximately
104[deg] west longitude), and in other areas of known potential seismic
activity east of the Rocky Mountain Front, seismicity must be evaluated
by the techniques presented in paragraph (f) of this section. If an
ISFSI or MRS is located on an NPP site, the existing geological and
seismological design criteria for the NPP may be used. If the existing
design criteria for the NPP is used and the site has multiple NPPs,
then the criteria for the most recent NPP must be used.
(c) Sites other than bedrock sites must be evaluated for their
liquefaction potential or other soil instability due to vibratory
ground motion.
(d) Site-specific investigations and laboratory analyses must show
that soil conditions are adequate for the proposed foundation loading.
(e) In an evaluation of alternative sites, those which require a
minimum of engineered provisions to correct site deficiencies are
preferred. Sites with unstable geologic characteristics should be
avoided.
(f) Except as provided in paragraphs (a)(2) and (b) of this
section, the DE for use in the design of structures, systems, and
components must be determined as follows:
(1) Geological, seismological, and engineering characteristics. The
geological, seismological, and engineering characteristics of a site
and its environs must be investigated in sufficient scope and detail to
permit an adequate evaluation of the proposed site, to provide
sufficient information to support evaluations performed to arrive at
estimates of the DE, and to permit adequate engineering solutions to
actual or potential geologic and seismic effects at the proposed site.
The size of the region to be investigated and the type of data
pertinent to the investigations must be determined based on the nature
of the region surrounding the proposed site. Data on the vibratory
ground motion, tectonic surface deformation, nontectonic deformation,
earthquake recurrence rates, fault geometry and slip rates, site
foundation material, and seismically induced floods and water waves
must be obtained by reviewing pertinent literature and carrying out
field investigations. However, each applicant shall investigate all
geologic and seismic factors (for example, volcanic activity) that may
affect the design and operation of the proposed ISFSI or MRS facility
irrespective of whether these factors are explicitly included in this
section.
(2) Geologic and seismic siting factors. The geologic and seismic
siting factors considered for design must include a determination of
the DE for the site, the potential for surface tectonic and nontectonic
deformations, the design bases for seismically induced floods and water
waves, and other design conditions as stated in paragraph (f)(2)(iv) of
this section.
(i) Determination of the Design Earthquake Ground Motion (DE). The
DE for the site is characterized by both horizontal and vertical free-
field ground motion response spectra at the free ground surface. In
view of the limited data available on vibratory ground motions for
strong earthquakes, it usually will be appropriate that the design
response spectra be smoothed spectra. The DE for the site is determined
considering the results of the investigations required by paragraph
(f)(1) of this section. Uncertainties are inherent in these estimates
and must be addressed through an appropriate analysis, such as a
probabilistic seismic hazard analysis (PSHA) or suitable sensitivity
analyses.
[[Page 54160]]
(ii) Determination of the potential for surface tectonic and
nontectonic deformations. Sufficient geological, seismological, and
geophysical data must be provided to clearly establish if there is a
potential for surface deformation.
(iii) Determination of design bases for seismically induced floods
and water waves. The size of seismically induced floods and water waves
that could affect a site from either locally or distantly generated
seismic activity must be determined.
(iv) Determination of siting factors for other design conditions.
Siting factors for other design conditions that must be evaluated
include soil and rock stability, liquefaction potential, and natural
and artificial slope stability. Each applicant shall evaluate all
siting factors and potential causes of failure, such as, the physical
properties of the materials underlying the site, ground disruption, and
the effects of vibratory ground motion that may affect the design and
operation of the proposed ISFSI or MRS.
(3) Regardless of the results of the investigations anywhere in the
continental U.S., the DE must have a value for the horizontal ground
motion of no less than 0.10 g with the appropriate response spectrum.
0
5. In Sec. 72.212, paragraph (b)(2)(i)(B) is revised to read as
follows:
Sec. 72.212 Conditions of general license issued under Sec. 72.210.
* * * * *
(b) * * *
(2) * * *
(i) * * *
(B) Cask storage pads and areas have been designed to adequately
support the static and dynamic loads of the stored casks, considering
potential amplification of earthquakes through soil-structure
interaction, and soil liquefaction potential or other soil instability
due to vibratory ground motion; and
* * * * *
Dated at Rockville, Maryland, this 10th day of September, 2003.
For the Nuclear Regulatory Commission.
Annette L. Vietti-Cook,
Secretary for the Commission.
[FR Doc. 03-23553 Filed 9-15-03; 8:45 am]
BILLING CODE 7590-01-P