D. I. Kaplan and S. M. Serkiz
Westinghouse Savannah River Company
Aiken, SC 29808

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The objective of this study was to quantify ¹²⁹I desorption of six waste materials in acidic and alkaline environments, simulating trench and cementitious disposal conditions. These data will be used in future performance assessment calculations to evaluate subsurface waste disposal at the SRS. Since performance assessment considers dose thousands of years in the future, it was also necessary to evaluate how ¹²⁹I desorption changed as a function of time. Laboratory column and batch studies were conducted with waste materials collected from the F-Area and H-Area Groundwater Treatment Units, operated by the Environmental Restoration Division. Thirteen liters of effluent were passed through each column. This volume represents about 1000 years worth of water passing through concrete and 100 years worth of water passing through soil.

The following key conclusions were made.

• Reasonably conservative ¹²⁹I Kd estimates were determined.

• Kd values measured in the acid rain environment were appreciably greater than those measured in the cement leachate environment.
• Kd values tended to increase as the amount of leachate that passed through the waste material increased. This was attributed to the more readily leachable ¹²⁹I being leached from the waste materials first, thereby leaving the more strongly held ¹²⁹I on the waste. Based on this explanation, the ¹²⁹I Kd values increased as the proportion of strongly bound ¹²⁹I on the waste increased.
• The Kd values of any given waste material varied between facilities. For example, the conservative ¹²⁹I Kd value for activated carbon in an acidic environment was 132,500 mL/g in the F-Area waste, 58,100 mL/g in the H-Area waste, and 7,400 mL/g in the Effluent Treatment Facility waste. Differences in the original material or differences in the treatment processes are likely responsible for these varying Kd values.

The measured Kd values for five of the six waste materials were appreciably greater than the default value of 2 mL/g used in the most recent performance assessment calculation. These larger Kd values may permit putting more ¹²⁹I laden waste in the vaults or trenches.

Key Words: I-129, Kd, CG-8 Resin, Dowex 21K Resin, Distribution Coefficients, Iodine, Desorption, Activated Carbon

2.0  Introduction

The E-Area Low-Level Waste (LLW) Facility is the site selected to store and dispose of a portion of the low-level radioactive waste generated at SRS. This facility is located on 200 acres, of which only 100 acres have been developed. The remaining 100 acres will allow for expansion of low-level waste disposal capacity.

Waste will be disposed in the LLW Facility in trenches, concrete vaults, and on waste pads. The concrete vaults include Low-Activity Waste Vaults and Intermediate-Level Vaults (ILV). Trench disposal includes rubble and miscellaneous wastes, intimately mixed cement-stabilized waste forms (e.g., ashcrete and blowcrete from the Consolidated Incinerator Facility), and cement-stabilized encapsulated waste (CSEW). The waste pads hold naval reactor components.

Iodine-129 is a primary risk driver and constituent limiting the amount of waste that can be disposed in the facility (McDowell-Boyer et al. 2000). The performance assessment modeling effort used the distribution coefficient (Kd value) parameter to quantify aqueous ¹²⁹I chemical interactions with the waste (i.e., extent of ¹²⁹I leaching). The Kd is defined as the radionuclide concentration in the solid phase divided by the concentration in the aqueous phase. The ¹²⁹I Kd value used in the most recent performance assessment calculations was 2 mL/g for waste in a cement disposal environment (i.e., in the ILV and in cement stabilized trenches) (McDowell-Boyer et al. 2000). The waste Kd value was based on literature cement-Kd values that were not SRS specific (Bradbury and Sarott 1995). Recent experimental work (Kaplan et al. 1999) has shown that ¹²⁹I Kd values of selected waste forms from the E-Area Low-Level Waste Facility were in fact appreciably greater than 2 mL/g. Reasonably conservative Kd values of the waste forms measured in a cementitious environment ranged from 600 mL/g (for activated carbon waste collected from the Effluent Treatment Facility) to 3100 mL/g (for GT-73 resin waste collected from the Effluent Treatment Facility). Special analyses were conducted using these larger Kd values and they suggested that more waste could be buried in the Low-Activity Waste Vault (Collard 2000a) and the Intermediate Level Vault (Collard 2000b) than previously calculated (McDowell-Boyer et al. 2000).

Another preliminary finding from the work of Kaplan et al. (1999) was that the waste Kd values were an order-of-magnitude greater in the presence of an acid rain environment than in a cement leachate environment. Reasonably conservative Kd values in the acid rain environment ranged from 7400 mL/g (for activated carbon waste collected from the Effluent Treatment Facility) to 10,000 mL/g (for GT-73 resin waste collected from the Effluent Treatment Facility). This suggests that although the cement vaults may provide superior physical protection to the waste form, the vaults may also create a chemical environment that enhances ¹²⁹I leaching from the waste forms. Thus, contrary to intuition, direct trench disposal may result in less ¹²⁹I migration than cement vault disposal.

The objectives of this study were:

1. to quantify ¹²⁹I desorption from six waste materials in an acidic and alkaline environment to simulate trench and cementitious disposal conditions,
2. to provide waste-specific reasonably conservative Kd values for future modeling efforts, and
3. to evaluate the manner in which ¹²⁹I desorption changed as a function of time.

The scope of this work involved evaluating six solid waste materials generated from the F- and H-Area Groundwater Treatment Units (GWTU) operated by the Environmental Restoration Division:

• F-Area CG-8 Cation Exchange Resin,
• H-Area CG-8 Cation Exchange Resin,
• F-Area Activated Carbon,
• H-Area Activated Carbon,
• H-Area Filtercake (primarily Fe-hydroxide sludge), and
• H-Area Dowex 21K Anion Exchange Resin.

Column and batch experiments were conducted with an acid rain simulant (a standard EPA rain simulant) and a cement leachate simulant to simulate trench and vault leaching conditions, respectively. The H-Area Dowex 21K resin was analyzed only by batch techniques. It was included in this study to compare with ¹²⁹I desorption Kd values measured from F-Area Dowex 21K resins (Kaplan et al. 1999). Observations by Scott Reboul (personnel communication, Environmental Restoration, WSRC) suggest that the two GWTUs had different ¹²⁹I retention efficiencies. He observed that ¹²⁹I breakthrough in the H-Area GWTU was appreciably longer than in the F-Area GWTU. This difference was presumably due to the differences in the quantities of ions in the feed solutions. The F-Area GWTU waste stream has an appreciably more ions (i.e., has a greater ionic strength) than the waste stream of the H-Area GWTU. These ions can compete for sorption sites on the resins.

Column and batch leaching studies with both acidic and cement leaching solutions were conducted. A standard, pH-3, acid-rain solution was used: 1) as a means of comparing data from this study to other results generated using this standard extraction technique, and 2) to provide an indication of the influence of acid rain on ¹²⁹I leaching from these wastes (ASTM D 1995). The other reason for selecting this extract is that it provides a measure of the iodine-leaching behavior of wastes in a shallow land disposal setting. The cement leachate simulant was designed to mimic the chemistry of a groundwater after passing through a concrete vault.

In the column studies, samples of each of the waste streams were leached with both the acidic and cement leaching solutions and the effluent was collected in 1-L aliquots (representing approximately 400 pore volumes). Thirteen liters of effluent were passed through each column. This volume represents the mass balance of about 1000 years worth of water passing through concrete and 100 years worth of water passing through soil. ¹²⁹I activity was determined in the "as-received" solid waste and in the 1-, 3-, 10-, and 13-L effluent aliquots.

Additionally, "as received" waste was subjected to a single batch extraction. In contrast to the column leaching experiments, where the leaching solution was in contact with the waste for ~10-minutes, samples were allowed to equilibrate for a week. These batch studies were designed to provide a maximum leach rate, or conservative Kd value, for the wastes. During the leaching tests, it was anticipated that a fraction of the ¹²⁹I would quickly and readily desorb (i.e., weakly sorbed fraction) from the waste materials with the first volume of leaching solution, leaving behind more strongly sorbed species that would desorb at a slower rate. Stated differently, it was expected that the ¹²⁹I Kd values measured during the leaching experiment would increase as more ¹²⁹I was leached.

Column studies were conducted to provide a measure of the change in ¹²⁹I-Kd values as a function of volume of leachate. The procedure was adapted from ASTM method D 4874-95, "Standard Test Method for Leaching Solid Material in a Column Apparatus" (ASTM 1995). Modification to the ASTM method (column dimensions, mass of waste material, and flow rate) were made to minimize waste generation, minimize the potential for radiation exposure, and reduce cost. A detailed description of the materials and methods used in this experiment are presented in Appendix A. A schematic representation of the experimental set-up is presented in Figure 1 and photographs of the actual column experiments in the radiological hood are presented in Figure 2 and Figure 3.

The waste materials used in the column experiments were:

• F-Area CG-8 – sulfonated functionalized polystyrene and divinylbenzene cation exchange resin in the sodium and hydrogen form (ResinTech, Cherry Hill, NJ),
• H-Area CG-8 - sulfonated polystyrene cation exchange resin (ResinTech, Cherry Hill, NJ),
• F-Area Activated Carbon,
• H-Area Activated Carbon, and
• H-Area Filtercake - primarily Fe-hydroxide generated during the flocculation process step.

Environmental Restoration Division and Environmental Monitoring Section personnel from WSRC collected and delivered these materials to SRTC. The samples were not preserved and were stored at room temperature prior to testing.

Two leaching solutions were used in this study: an acid-rain simulant and a cement-leachate simulant. The acid-rain simulant was made in 50-L batches and was prepared by adding drops of a 60/40 wt-% mixture of sulfuric acid/nitric acid to deionized water until a pH of 3.0 (EPA Method 1320, EPA 1986) was achieved (approximately 120 drops/50-L). The cement leachate simulant was based on the chemical composition data of a cement leachate presented by Serne et al. (1987). The recipe for a 50-L (pH 12.3) solution included: 13.70-g CaCO₃, 10.55-g CaOH₂, 69.30-g KOH, 173.57-g NaOH, and ~120 drops of 60/40 wt-% sulfuric acid/nitric acid. Following a 2-hr mixing period, the leaching solution was filtered to remove any precipitated or undissolved materials.

Ten-mL of "as-received" waste material were placed into 20-mL plastic columns with small glass wool plugs on the top and bottom of the sorbent material. Fourteen-gauge silicone tubing was used to pump the influent leaching solution from a 50-L carboy into the bottom of the column (up flow mode), and out the top of the column into 1-L bottles. Influent flow rate was 15 ± 0.25 mL/hr. Residence time of the leachate in the column was approximately 10 minutes. It required more than two months to pass the 13-L through the columns (pumps had to be turned off over weekend due to radiological safety concerns related to leaving the columns running unattended). Thirteen sequential 1-L effluent samples were collected from each sorbent material. Effluent samples and "as received" (pre-leaching) waste material were submitted to General Engineering Laboratories (Charleston, SC) for ¹²⁹I analyses following the method described below. For quality control purposes, two splits, two background blank solutions, and two ¹²⁹I-spiked solutions were included with these samples. The results of these quality control samples were all acceptable.

The ¹²⁹I concentration data were then used to calculate Kd values using Equation 1,

      (1)

where I_solid is the ¹²⁹I activity in the solid waste material at the start of the experiment (pCi/g), I_aq(i) is the ¹²⁹I activity in the i^th 1-L leachate aliquot (pCi/mL), M_solid is the dry-mass of the solid waste (g), and V_aq(i) is the aqueous volume of the i^th 1-L leachate aliquot (mL).

In Equation 1, the ¹²⁹I concentration associated with the solid phase (the numerator) is not measured directly. Instead, it is estimated by subtracting the total activity leached into the aqueous phase from the initial activity associated with the solid phase. All Kd values were reported on a dry weight basis.

Figure 1.   Schematic Representation of Column Experimental Set-up

Figure 2.  Acid-Rain Columns, from Left to Right: F-Area Activated Carbon, H-Area Activated
Carbon, F-Area CG-8, H-Area CG-8, and H-Area Filtercake

¹²⁹I Kd values were measured using standard methods (ASTM 1984). A detailed description of the materials and methods used in this experiment are presented in Appendix A and a schematic representation of the experimental setup is shown in Figure 4. Instead of a 24-hr equilibration period, a 7-day equilibration period was used to ensure that a truly conservative Kd value was measured. The Kd values were measured using the same waste materials as were used in the column experiment plus H-Area Dowex 21K resin (trimethylamine functionalized chloromethylated copolymer of styrene and divinylbenzene in the chloride form; The Dow Chemical Company, Midland, MI). These materials were placed in contact with the acid-rain and cement-leachate simulants described for the column experiment. Five grams of waste material, except for CG-8, which 50-g was used, were placed in contact with 475-mL leaching solution. A greater solid-to-liquid ratio was used with the CG-8 resins because they had lower initial¹²⁹I activities. A greater solid-to-liquid ratio was required to improve detection of ¹²⁹I in the final equilibration solution. The samples were gently mixed for 30-sec by hand and then left in a radiological hood. The suspensions were allowed to equilibrate for 7-days, during which time the 500-mL sample bottles were gently mixed once per day for 30-sec. Following the 7-day equilibration period, leaching solutions were filtered (0.45-m m) and the filtrates were submitted to General Engineering Laboratory for ¹²⁹I analyses.

Kd values were calculated using Equation 2,

      (2)

where I_solid is the ¹²⁹I activity in the solid at the start of the equilibration period (pCi/g), M_solid is the mass of the solid (g), V_aq is the volume of the aqueous phase (mL), and I_Aq(final) is the aqueous ¹²⁹I activity at the end of the equilibration period (pCi/mL). All Kd values were reported on a dry weight basis.

Column effluent samples and "as received" sorbent materials from leaching tests were analyzed by the General Engineering Laboratory (Charleston, SC) by gamma spectroscopy. Details of analytical procedures and QA requirements for these analyses can be obtained from their office.

During the laboratory portion of this study, the standard QA practices described in the WSRC QA Manual 1Q were followed throughout this study. For quality control purposes, two split samples, four background blank solutions (2 acid-rain simulant and two cement leachate simulant), and two ¹²⁹I-spiked solutions were included with experiment samples. The results of these quality control samples were acceptable (see Appendix B).

Table 1 shows the total ¹²⁹I activity in the "as received" waste samples. The ¹²⁹I activities are reported on a dry weight basis and on a wet weight (as-received) basis. Knowledge of the ¹²⁹I activity on a dry weight basis is necessary for calculating Kd values. The moisture content varied between samples from 40 to 81%. The coefficient of variance values of the ¹²⁹I activity generally increased as the ¹²⁹I activity decreased, suggesting that the variance can be attributed to analytical issues, as opposed to heterogeneity in the sample. Table 1 also contains previously reported ¹²⁹I activity values that were summarized by Carroll. These activity values are assumed to be on a wet weight basis. They are consistent with the measured values, except for the H-Area Carbon, which was previous reported to be about an order-of-magnitude greater than was detected in the samples used in this study.

The column experiments provided information that was used to calculate ¹²⁹I Kd values as a function of type of leachate and amount of leachate passed through the column (Table 2). A number of conclusions can be made from these data.

1. Kd values measured in the acid rain environment were appreciably greater than those measured in the cement leachate environment.
2. Kd values tended to increase as the amount of leachate that passed through the waste material increased. This is likely attributed to the more readily leachable ¹²⁹I being leached from the waste materials first, thereby leaving the more strongly held ¹²⁹I on the waste. Based on this explanation, the ¹²⁹I Kd values increased with time (and effluent volume) as the proportion of strongly bound ¹²⁹I on the waste increased.
3. After only ~3-L of effluent (equivalent to ~240-yr through cement and ~24-yr through soil, based on the assumptions in footnote 4) had been introduced into the columns, the ¹²⁹I Kd values increased appreciably, often increasing more than an order of magnitude.
4. A ranking of the waste materials by their overall Kd values is:

Activated carbon >> CG-8 = Filtercake.

5. The Kd values of any given waste material varied between facilities. Specifically, activated carbon Kd values were generally greater in the F-Area waste than in the H-Area waste; the converse was true for the CG-8 cation resin.

 

¹²⁹I Kd values were measured from batch experiments to provide a comparison with the Kd values measured from the column experiments. These two methods measure two different processes, yet each has advantages and disadvantages for estimating Kd values to be used in performance assessments. The column experiment permits measurement of the Kd value under the proper solid-to-liquid ratio, however does not permit making the measurement with the proper contact time between the leachate and the waste material. Whereas the batch experiment permits mimicking the contact time expected in an aquifer, but does so at an unrealistic solid-to-liquid ratio. The solid-to-liquid mass ratio in nature or in a column is about 1:0.4. In the batch experiments conducted for this study this ratio was 1:95 or 1:9.5.

The problem with conducting a column experiment at very slow flow rates, such as 4-mL/yr, is that it is difficult, perhaps impossible, to obtain such low flow rates, roughly 1 drop per hour from the column. Also, at this pumping rate, there are problems with sample evaporation and generation of a sufficient volume of liquid for analytical purposes. Column experiments conducted at flow rates faster than is expected in the field do not provide the proper solid-liquid contact time. In the column experiments conducted for this study, the contact time of the water was ~10 min (see footnote 4 for values of parameters used to make this calculation). This contact time is 1250% longer than that used by Kaplan et al. (1999), which was 0.8 min. The contact time used in this study is appreciably less than that expected under field conditions. The problem with a shorter contact time is that it would tend to overestimate actual Kd values. This occurs because the concentration of the ¹²⁹I in the leachate, the denominator of the measured Kd value (Equation 2), would be reduced due to mass-transfer kinetic limitations of ¹²⁹I desorption from the solid to the liquid phase. To provide a contact time that is more similar to expected field conditions, batch experiments were conducted with a contact time (equilibration period) of 7-days. It was anticipated that the greater contact time would more closely simulate actual field conditions and would permit a greater amount of ¹²⁹I to be released from the solids, thereby resulting in a lower Kd value.

The batch Kd values are reported in Table 3. The following conclusions can be made from this data.

1. Batch Kd values tended to be less than the values generated from the column studies (Table 2). Again, this can be attributed to the greater contact time between the leaching solution and the waste material, permitting more ¹²⁹I to be leached from the solid waste.
2. As was the case with the Column Experiment, Kd values measured in acid rain simulant were greater than those measured in cement leachate simulant. The activated carbon Kd value measured in the cement leachate simulant was more than two orders-of-magnitude less than the Kd value measured in the acid rain simulant.
3. A ranking of the waste materials by their overall Kd values is:

Activated Carbon >> Dowex 21K >> Filtercake > CG-8.

4. The large standard deviation associated with the activated carbon samples can be attributed to the below detection limit ¹²⁹I values (~1 pCi/L) measured in the aqueous samples after contact with the activated carbon. The below detection limit values indicate that very little ¹²⁹I leached from the activated carbon waste during the one-week equilibration period.

Table 3. ¹²⁹I Kd Values for Various Waste Forms Determined from Batch Experiments Using
Simulated Acid Rain and Cement Leachate (Duplicated Samples).

The lowest measured Kd value was used as the basis for the reasonably conservative Kd estimates, except for the H-Area Filtercake in an acid rain environment (Table 4) and the F-Area CG-8 resin in a cement leachate environment (Table 5). We elected not to follow this easily defensible strategy for the selection of these two reasonably conservative Kd estimates because the lowest Kd values were suspect. In the case of the F-Area CG-8 resin in a cement leachate environment, the lowest Kd value was immeasurable, 0 mL/g. This value is contradictory to the observation that the resins were able to remove ¹²⁹I from the GWTU waste stream, albeit, only small amounts. By virtue of having removed ¹²⁹I from the waste stream, the resin must have a non-zero Kd value. The average of the two batch Kd values, 3 mL/g, was selected as the reasonably conservative value for this waste material.

The reasonably conservative Kd value for the H-Area Filtercake in an acid rain environment was based on the average of the two lowest values, the two batch replicates. The lowest value was suspect insofar that it was 3.9 times smaller than its replicate and the replicate was more in line with the other measured values.

The reasonably conservative Kd estimates reported by Kaplan et al. (1999) are presented in Appendix C and summarized in Table 6. The experimental conditions of the studies in Kaplan et al. (1999) were similar to those used in this report, with the notable exception that the flow rate of the column experiments was 0.8 mL/hr, compared to 15.0 mL/hr used in this study. This difference would be expected to lead to the Kd values reported in Kaplan et al. (1999) to be somewhat larger than those reported in this study.

Three interesting comparisons can be made with these data. The conservative ¹²⁹I Kd estimates for ETF (Effluent Treatment Facility) were 7,400 mL/g in the acid-rain simulant and 600 mL/g in the cement-leachate simulant (Kaplan et al. 1999). For the F-Area Carbon, the same estimates were 132,500 mL/g in the acid-rain simulant and 880 mL/g in the cement-leachate simulant (Table 4 and Table 5). For the H-Area Carbon, the same estimates were 58,100 mL/g in the acid-rain simulant and 320 mL/g in the cement-leachate simulant.

Table 6 also reports ¹²⁹I Kd values for F-Area Dowex 21K. In this study, the same source resin from H-Area GWTU was evaluated. The H-Area resin had a Kd value of 6800 mL/g in an acid-rain simulant and 2800 mL/g in a cement-leachate simulant. For the F-Area resins, the Kd value was 15,600 mL/g in an acid-rain simulant and 1960 mL/g in the cement-leachate simulant.

These comparisons revealed that:

1. ¹²⁹I-Kd values in the acidic environment were one or two orders-of-magnitude greater than those measured in the cement leachate environment.
2. Kd values of the activated carbon varied, depending on the source of the waste. This could be attributed to the chemical differences in the waste stream, process time, or to the differences in the treatment train. It may also be attributed to different sources of activated carbon used in the three facilities.

The measured Kd values for five of the six waste materials were appreciably greater than the default value of 2-mL/g used in the most recent performance assessment calculation (McDowell-Boyer et al. 2000). These larger Kd values may permit putting more ¹²⁹I laden waste in the vaults or trenches. The following key conclusions can be made from the data presented in this report.

• Reasonably conservative ¹²⁹I-Kd values (mL/g) for the two environments follow.

• Kd values measured in an acid rain environment were appreciably greater than those measured in a cement leachate environment.
• Kd values tended to increase as the amount of leachate that passed through the waste material increased. This was attributed to the more readily leachable ¹²⁹I being leached from the waste materials first, thereby leaving the more strongly held ¹²⁹I on the waste. Based on this explanation, the ¹²⁹I Kd values would increase as the proportion of strongly bound ¹²⁹I on the solid increased.
• After only ~3-L of effluent had been introduced into the columns (equivalent to ~240 years through cement and ~24 years through soil, based on the assumptions in footnote 4), the ¹²⁹I-Kd values increased appreciably, often increasing more than an order of magnitude.
• The Kd values of waste generated in one process are not applicable to similar waste materials generated from another process. For example, the conservative ¹²⁹I Kd value for activated carbon in an acidic environment was 132,500-mL/g in the F-Area waste, 58,100-mL/g in the H-Area waste, and 7,400-mL/g in the Effluent Treatment Facility waste. Differences in the original material or differences in the treatment processes are likely responsible for these varying Kd values.
• Batch Kd values tended to be less than the values generated from the column studies. This is likely attributed to the greater contact time with the solution and the waste material, permitting more ¹²⁹I to be leached from the solid waste.

Cathy Coffey, from the Liquid Waste Processing Support Group, conducted the laboratory work described in this report. Bob Lasswitz, from the Environmental Monitoring - Sample Groups, collected and transported radiological resin samples from the F- and H-Area Treatment Facilities to our laboratory. General Engineering Laboratories, Charleston, South Carolina conducted all ¹²⁹I analyses described in this report. Jim Cook and Tom Butcher provided thorough reviews of this document.

1. ASTM. Standard Test Method for Distribution Ratios by the Short-Term Batch. Method D 4319-83. Annual Book of ASTM Standards, Vol. 04.08. (1984).
2. ASTM. Standard Test Method for Leaching Solid Material in a Column Apparatus. D 4874-95. Annual Book of ASTM Standards, Vol 11.04 (1995).
3. Bradbury, M. H., and F. A. Sarott. Sorption Databases for the Cementitious Near-Field of a L/ILW Repository for Performance Assessment. ISSN 1019-0643, Paul Scherrer Institut, Wurenlingen and Villigen, Switzerland (1995).
4. Collard, L. B. Special Analysis for Disposal of High-Concentration I-129 Waste in the Intermediate Level Vaults at the E-Area Low-Level Facility. WSRC-RP-99-01070, Westinghouse Savannah River Company, Aiken SC (2000a).
5. Collard, L. B. Special Analysis for Disposal of High-Concentration I-129 Waste in the Low-Activity Waste Vaults at the E-Area Low-Level Waste Facility. WSRC-RP-2000-00138. Westinghouse Savannah River Company, Aiken, SC (2000b).
6. EPA (U.S. Environmental Protection Agency). Multiple Extraction Procedure, Method 1320. In: Test Methods for Evaluating Solid Waste Physical/Chemical Methods, SW-846. Office of Solid Waste, Washington, DC (1986).
7. Kaplan, D. I., S. M. Serkiz, and N. C. Bell. I-129 Desorption from SRS Water Treatment Media from the Effluent Treatment Facility and the F-Area Groundwater Treatment Facility. WSRC-TR-99-00270. Westinghouse Savannah River Company, Aiken, SC (1999).
8. McDowell-Boyer, L., A. D. Yu, J. R. Cook, D. C. Kocher, I. L. Wilhite, H. Homes-Burns, and K. E. Young. Radiological Performace Assessment for the E-Area Low-Level Waste Facility. WSRC-RP-94-218 Rev. 1, Westinghouse Savannah River Company, Aiken SC (2000)
9. Serne, R. J., L. J. Criscenti, and D. M. Strachan. Comparison of Geochemical Code Predictions and Laboratory Test Results for Uranium Leaching/adsorption from Cement. PNL-11508. Pacific Northwest National Laboratories, Richland, WA (1987).

1. Determine ¹²⁹I Kd values by the column leaching method of five waste materials under simulated acid rain and cementitious conditions.
2. Measure the desorption-¹²⁹I-K_d of 6 waste materials by batch method to provide a measure of a desorption-K_d at steady state. The intent of collecting this data is to compare it to the desorption K_d measured under non-steady state conditions.

1. F-Area Activated Carbon
2. H-Area Activated Carbon
3. F-Area CG-8
4. H-Area CG-8
5. H-Area Filter Cake
6. H-Area Dowex
7. Cement leachate simulant: The simulated cement pore water leaching solution (50L) will be prepared based on the chemical composition of a cement leachate reported by Serne et al. (1987): CaCO₃ (13.70 g), CaOH₂ (10.55 g), KOH (69.30 g), and NaOH (173.57 g). Following a ½ day mixing period, pass the resulting solution through a 0.45-m m filter to remove any precipitated or undissolved materials.
8. Acid rain simulant: Add drops of a 60/40 wt % mixture of sulfuric acid/nitric acid to 50 L of deionized water until a pH of 3.0 is achieved (approximately 120 drops/50L) (EPA Method 1320, EPA 1986).

1. Determine the dry weights of the 6 wastes by measuring the appropriate weights for Table 1.
2. In triplicate, add ~10 g of each waste into a weighing boat.
3. Leave moist waste in weighing boats in hood to air dry for 1 week.
4. Record dry weight.

1. The experimental matrix is shown in Table A1.
   
   

Table A1. Experimental matrix.
ID #	Resin	Leachate	Reps	Targeted Moisted-Wet Added (g)	Moist-Wet Added (g)
801	F-Area Carbon	Simulated acid rain	1	5
802	F-Area Carbon	Simulated acid rain	2	5
803	F-Area Carbon	Simulated cement leachate	1	5
804	F-Area Carbon	Simulated cement leachate	2	5
805	H-Area Carbon	Simulated acid rain	1	5
806	H-Area Carbon	Simulated acid rain	2	5
807	H-Area Carbon	Simulated cement leachate	1	5
808	H-Area Carbon	Simulated cement leachate	2	5
809	F-Area CG8	Simulated acid rain	1	50
810	F-Area CG8	Simulated acid rain	2	50
811	F-Area CG8	Simulated cement leachate	1	50
812	F-Area CG8	Simulated cement leachate	2	50
813	H-Area CG8	Simulated acid rain	1	50
814	H-Area CG8	Simulated acid rain	2	50
815	H-Area CG8	Simulated cement leachate	1	50
816	H-Area CG8	Simulated cement leachate	2	50
817	H-Area Filter Cake	Simulated acid rain	1	5
818	H-Area Filter Cake	Simulated acid rain	2	5
819	H-Area Filter Cake	Simulated cement leachate	1	5
820	H-Area Filter Cake	Simulated cement leachate	2	5
821	H-Area Dowex	Simulated acid rain	1	5
822	H-Area Dowex	Simulated acid rain	2	5
823	H-Area Dowex	Simulated cement leachate	1	5
824	H-Area Dowex	Simulated cement leachate	2	5
825	blank	Simulated acid rain	1
826	blank	Simulated cement leachate	1



2. According to Table A1, add either 5.0 ± 0.1 g or 50 ± 1 g waste and 475 ± 1 mL of leaching water to 500-mL plastic containers. Record actual weight of waste added.
3. Gently mix samples once per working day for 30 seconds for 1 week.
4. Pass through a 0.45-m m filter.
5. Give aqueous samples to Bob Lassiwitz for ¹²⁹I analysis.

1. The experimental matrix for this study is presented in Table A2.
2. Add ~10 mL of waste material to disposable 20-mL plastic columns with small glass wool plugs on the top and bottom of the sorbent material. Use 14--gauge silicone tubing to transfer the influent leaching solution from the 50-L carboy, through a peristaltic pump, into the bottom of the column (up-flow mode), and out the top of the column into 1-L bottles.
3. Adjust the pump so that it delivers 10 ± 2 mL/hr. Introduce into the bottom of each column, 20-L of influent. It should take ~12 weeks for all 20-L to be introduced into column.
4. Submit to Bob Lassiwitz the follow 1-L effluent aliquots for ¹²⁹I analysis: 1, 3, 10, and 20-L samples.
5. After the experiment is completed, dry in hood all waste from column in weighing boats and then submit to Bob Lassiwitz for ¹²⁹I analysis.
6. Also submit 50-g of "as received" waste for ¹²⁹I analysis.
7. For QA, please include a ¹²⁹I spiked solution (from Dave Dipret), and one blank acid rain simulant and one blank cement leachate simulant.

10.0  Appendix B: I-129 Quality Control Results

11.0  Appendix C: Previously Reported ¹²⁹I Kd Values of Waste Materials