May 22, 2009 

Mr. Thomas Gutmann, Director 

Waste Disposition Programs Division 

U.S. Department of Energy 

Savannah River Operations Office 

P.O. Box A 

Aiken, SC 29802 

SUBJECT: NUCLEAR REGULATORY COMMISSION MARCH 25-26, 2009 ONSITE 

OBSERVATION REPORT FOR THE SAVANNAH RIVER SITE SALTSTONE 

FACILITY 

Dear Mr. Gutmann: 

The enclosed report describes the U.S. Nuclear Regulatory Commission’s (NRC’s) onsite 

observation activities on March 25-26, 2009, at the Savannah River Site (SRS) Saltstone 

Facility. This onsite observation was conducted in accordance with Section 3116 of the 

Ronald W. Reagan National Defense Authorization Act for Fiscal Year 2005 (Section 3116), 

which requires NRC to monitor disposal actions taken by DOE for the purpose of assessing 

compliance with the performance objectives set out in 10 CFR Part 61, Subpart C. The activities 

conducted during the site visit were consistent with those described in the NRC’s monitoring 

plan for salt waste disposal at SRS (dated May 3, 2007) and NRC’s staff guidance for activities 

related to waste determinations (NUREG-1854, dated August, 2007). 

Similar to NRC’s previous visits, this onsite observation at SRS was primarily focused on 

assessing compliance with two performance objectives, 10 CFR 61.41, protection of the general 

population from releases of radioactivity, and 10 CFR 61.43, protection of individuals during 

operations, by observing DOE’s ongoing construction of disposal cells at the Saltstone Disposal 

Facility (SDF), requesting additional information about the methods used by DOE to estimate the 

inventory of radionuclides in the SDF, and discussing staff questions and comments on 10 of 14 

technical reports provided to NRC since November 2008. Since the quality of saltstone grout is 

relevant to the long-term stability of the disposal facility after its closure, this observation also 

partially assessed the performance objective in 10 CFR 61.44, stability of the disposal site after 

closure. 

One new open issue was identified by NRC staff, in which staff determined that DOE should 

provide additional support for assumptions that: (1) technetium-99 in salt waste is converted to 

its reduced chemical form in saltstone grout during the curing of saltstone grout, and is thereby 

strongly retained in saltstone grout, and (2) the sorption of dissolved technetium-99 onto 

saltstone grout and vault concrete is consistent with Kd values for technetium-99 that were 

assumed in the performance assessment. NRC and DOE staff also identified 21 DOE follow-up 

actions, which are mostly in response to NRC staff questions on 10 of 14 technical reports, 

which DOE provided to NRC staff since November 2008. NRC staff will continue its reviews of 

these reports, pending DOE responses to the follow-up actions identified in the attached report. 
T. Gutmann 2

Based on our observations, NRC continues to conclude that there is reasonable assurance that 

the applicable criteria of Section 3116 can be met if key assumptions made in DOE’s waste 

determination analyses prove to be correct. In accordance with the requirements of Section 

3116 and consistent with NRC’s monitoring plan for the salt waste disposal facility, NRC will 

continue to monitor DOE’s disposal actions at SRS. The monitoring activities are expected to be 

an iterative process. Several onsite observation visits and technical reviews may be necessary 

in order to obtain the information needed to close all of the current open issues, as well as 

issues that may be opened in the future. 

On March 26, 2009, at the conclusion of the onsite observation activities, NRC staff members 

discussed the topics addressed in this report with you, other DOE representatives, and 

representatives from the State of South Carolina. If you have any questions or need additional 

information regarding this report, please contact David Brown of my staff at (301) 415-6116. 

Sincerely, 

/RA/ 

Patrice Bubar, Deputy Director 

Division of Waste Management 

 and Environmental Protection 

Office of Federal and State Materials 

 and Environmental Management Programs 

Enclosure: 

NRC Observation Report 

cc: w encl: 

S. Wilson 

Federal Facilities Liaison 

Environmental Quality Control Administration 

South Carolina Department of Health 

 and Environmental Control 

2600 Bull Street 

Columbia, SC 29201-1708 
T. Gutmann 2

Based on our observations, NRC continues to conclude that there is reasonable assurance that 

the applicable criteria of Section 3116 can be met if key assumptions made in DOE’s waste 

determination analyses prove to be correct. In accordance with the requirements of Section 

3116 and consistent with NRC’s monitoring plan for the salt waste disposal facility, NRC will 

continue to monitor DOE’s disposal actions at SRS. The monitoring activities are expected to be 

an iterative process. Several onsite observation visits and technical reviews of may be 

necessary in order to obtain the information needed to close all of the current open issues, as 

well as issues that may be opened in the future. 

On March 26, 2009, at the conclusion of the onsite observation activities, NRC staff members 

discussed the topics addressed in this report with you, other DOE representatives, and 

representatives from the State of South Carolina. If you have any questions or need additional 

information regarding this report, please contact David Brown of my staff at (301) 415-6116. 

Sincerely, 

Patrice Bubar, Deputy Director 

Division of Waste Management 

 and Environmental Protection 

Office of Federal and State Materials 

 and Environmental Management Programs 

Enclosure: 

NRC Observation Report 

cc: w encl: 

S. Wilson 

Federal Facilities Liaison 

Environmental Quality Control Administration 

South Carolina Department of Health 

 and Environmental Control 

2600 Bull Street 

Columbia, SC 29201-1708 

DISTRIBUTION: 

RidsOpaMail RidsOgcMailCenter RidsOcaMailCenter 

ML091320439 

OFC DWMEP:PM DWMEP:LA DWMEP:BC DWMEP:BC DWMEP:DD 

NAME DBrown AWalker-Smith CMcKenney GSuber PBubar 

DATE 5/13/09 5/14/09 5/14/09 5/18/09 5/22/09 

OFFICIAL RECORD COPY 
NUCLEAR REGULATORY COMMISSION MARCH 25-26, 2009 ONSITE OBSERVATION 

REPORT FOR THE SAVANNAH RIVER SITE SALTSTONE FACILITY 

EXECUTIVE SUMMARY 

The Nuclear Regulatory Commission staff conducted its fourth onsite observation visit of the 

Saltstone Facility at the Savannah River Site (SRS) on March 25-26, 2009. This visit was intended 

to focus on two of the four performance objectivesC10 CFR 61.41, “protection of the general 

population from releases of radioactivity”, and 10 CFR 61.43, “protection of individuals during 

operations”Cby obtaining information on The U.S. Department of Energy (DOE) saltstone 

wasteform production and saltstone disposal facility operations and verifying DOE=s radiation 

protection measures for relevant operations. Because the saltstone wasteform production 

operations could impact the long-term stability of the disposal facility after its closure, this 

observation also was intended to partially assess compliance with the performance objective in 

10 CFR 61.44, stability of the disposal site after closure. This report provides a description of NRC 

onsite observation activities and identifies NRC observations from the visit. Based on the results of 

the visit, the NRC continues to have reasonable assurance that the performance objectives of 

10 CFR 61 can be met in the areas reviewed. 

There is one new open issue as a result of the staff’s ongoing technical reviews of 14 technical 

reports provided to NRC staff since November 2008, which was discussed with observation 

participants on March 26. In Open Issue 2009-1, staff has determined that DOE should provide 

additional support for assumptions that: (1) technetium-99 in salt waste is converted to its reduced 

chemical form in saltstone grout during the curing of saltstone grout, and is thereby strongly 

retained in saltstone grout, and (2) the sorption of dissolved technetium-99 onto saltstone grout 

and vault concrete is consistent with Kd values for technetium-99 that were assumed in the 

performance assessment. A summary of the staff’s other observations and conclusions is 

provided below: 

Disposal Cell Construction 

• The staff observed ongoing construction at Saltstone Disposal Facility Cells 2A and 2B. At the 

time of the staff’s visit, the base mud mat, geosynthetic clay liner and 100-mil high-density 

polyethylene liner, Type V mud mat and floor had been installed for Cells 2A and 2B, and the 

floor was curing. Rebar pedestals had been cast in place for the 48 columns that will support 

the roof in each cell. Forms were installed at several locations on the ground outside the cells 

for casting 32 15-ton wall panels for each cell, but no wall panels had been cast. DOE has two 

follow-up actions from this activity relating to NRC staff requests for (i) photographs of 

construction joints that will be covered by successive layers of construction material before 

NRC staff can return to directly observe the joints, and (ii) construction design drawings. 

Saltstone Radionuclide Inventory 

• The staff discussed with DOE and DOE contractor staff the assumptions and data used to 

quantify the inventory of radionuclides in liquid waste that is transferred to the SDF. DOE has 

three follow-up actions pertaining to NRC staff requests for additional information that supports 

the quarterly Saltstone Permit Reports published on the DOE Savannah River Operations 

office website. 
2 

Ongoing NRC Staff Technical Reviews 

• The NRC staff discussed with DOE and DOE contractor staff 10 of 14 technical reports 

provided to NRC staff since November 2008. These reports covered the results of studies on 

soil contamination in the vicinity of Vault 4 and the results of physical and chemical studies on 

both actual disposal cells (e.g., video of Vault 4, Cell G), and laboratory-prepared saltstone 

grout and vault concrete. Aside from the open issue described above, DOE has 16 follow-up 

actions related to staff questions on these studies. 
3 

1.0 BACKGROUND 

Section 3116 of the Ronald W. Reagan National Defense Authorization Act for Fiscal 

Year 2005 (Section 3116) authorizes the DOE, in consultation with the NRC, to determine 

that certain radioactive waste related to the reprocessing of spent nuclear fuel is not highlevel waste, provided certain criteria are met. Section 3116 also requires NRC to monitor 

DOE disposal actions to assess compliance with the performance objectives in 

10 CFR Part 61, Subpart C. 

On March 31, 2005, DOE submitted a “Draft Section 3116 Determination, Salt Waste 

Disposal Savannah River Site” to demonstrate compliance with the Section 3116 criteria 

including demonstration of compliance with the performance objectives in 10 CFR Part 61, 

Subpart C (DOE, 2005). In its consultation role, the NRC staff reviewed the draft waste 

determination and concluded that there was reasonable assurance that the applicable 

criteria of Section 3116 could be met, provided certain assumptions made in DOE's 

analyses are verified via monitoring. NRC documented the results of its review in a 

technical evaluation report (TER) issued in December 2005 (NRC, 2005). DOE issued a 

final waste determination in January 2006 taking into consideration the assumptions, 

conclusions, and recommendations documented in NRC’s TER (DOE, 2006). 

To carry out its monitoring responsibility under Section 3116, NRC plans to perform three 

types of activities: (i) technical reviews, (ii) onsite observations, and (iii) data reviews. 

These activities will focus on key assumptions—called “factors”—identified in the NRC 

monitoring plan for saltwaste disposal at SRS (NRC, 2007). Technical reviews generally 

will focus on obtaining additional model support for assumptions DOE made in its 

performance assessment (PA) that are considered important to DOE's compliance 

demonstration. Onsite observations generally will be performed to (i) observe the collection 

of data (e.g., observation of waste sampling used to generate radionuclide inventory data) 

and review the data to assess consistency with assumptions made in the waste 

determination, or (ii) observe key disposal (or closure) activities related to technical review 

areas (e.g., slag and other material storage, grout formulation and preparation, and grout 

placements). Data reviews will supplement technical reviews by focusing on monitoring 

data that may also indicate future system performance or by reviewing records or reports 

that can be used to directly assess compliance with performance objectives. 

On March 25-26, 2009, the NRC staff onsite observation visit at SRS focused primarily on 

two performance objectives, 10 CFR 61.41, protection of the general population from 

releases of radioactivity, and 10 CFR 61.43, protection of individuals during operations, by 

observing DOE’s ongoing construction of disposal cells at the Saltstone Disposal Facility 

(SDF), requesting additional information about the methods used by DOE to estimate the 

inventory of radionuclides in the SDF, and discussing staff questions and comments on 

10 of 14 technical reports provided to NRC since November 2008. Because the vaults and 

saltstone grout could impact the long-term stability of the disposal facility after its closure, 

this observation also was intended to partially assess compliance with the performance 

objective in 10 CFR 61.44, stability of the disposal site after closure. Future visits will 

assess the performance objective in 10 CFR 61.42, protection of individuals against 

inadvertent intrusion, and also continue to assess DOE compliance with the other 

performance objectives. 
4 

Saltstone Facility Operational Status at the time of the Observation 

At the request of NRC staff, DOE and DOE contractor staff provided a brief overview of 

operations at the Saltstone Facility since the last onsite observation (NRC, 2008). DOE 

explained that salt waste in Tank 50 was not processed at the SPF between April 2008 and 

December 2008. In January, the transfer of material from Tank 50 to the SPF resumed. In 

addition, batch 1 of salt waste in Tank 49 was treated at the Actinide Removal 

Process/Modular Caustic Side Solvent Extraction process (ARP/MCU) through September 

2008. Batch 2 of ARP/MCU feed was qualified in November and December 2008, with 

approximately 70,000 gallons of batch 2 waste having since been sent to ARP/MCU for 

treatment. 

2.0 NRC ONSITE OBSERVATION ACTIVITIES 

2.1 Disposal Cell Construction 

 NRC staff monitors ongoing construction of disposal cells, as described in section 3.2.3, 

“Vault Construction,” of the staff’s monitoring plan (NRC, 2007). 

2.1.1 Observation Scope 

The general purpose of NRC staff observations of ongoing construction of Saltstone 

Disposal Facility Cells 2A and 2B is to identify noticeable deviations from the vault 

design,ocusing on changes that could affect potential pathways for water to intrude into the 

vaults, such as penetrations or joints. A specific objective of this monitoring visit was to 

become familiar with the construction area and methods being used to construct new 

disposal cells. 

2.1.2 Observation Results 

The staff observed ongoing construction at Saltstone Disposal Facility Cells 2A and 2B. At 

the time of the staff’s visit, the base mud mat, geosynthetic clay liner and 100-mil highdensity polyethyline liner, Type V mud mat and floor had been installed for Cells 2A and 

2B, and the Type V concrete floor was curing under plastic covers. Rebar pedestals had 

been cast in place in the floor for the 48 columns that will support the roof in each cell. 

Forms were constructed at various locations on the ground outside the cells for casting 

32 15-ton wall panels for each cell, but no wall panels had been cast at the time of the 

observation. 

2.1.3 Conclusions and Followup Actions 

No issues or concerns were identified during the observation of disposal cell construction. 

Staff plans to return to the site in late May or June 2009 to observe installation of wall 

panels. In the interim, DOE agreed to take photographs of construction joints, prior to 

covering the joints with additional construction layers or concrete. At NRC staff’s request, 

DOE will provide a complete set of Vault 2 design drawings. NRC staff will provide specific 

requests for construction photographs to DOE after reviewing the drawings. 
5 

DOE Follow-up Actions

1. DOE agreed to take photographs of construction joints, prior to covering the joint with 

additional construction layers or concrete. 

2. At NRC staff’s request, DOE will provide a complete set of Vault 2 design drawings. 

 Action 2 complete: see NRC, 2009 

2.2 Saltstone Radionuclide Inventory 

 NRC staff monitors feed tank sampling and waste sampling, as described in section 3.1.1, 

“Data Reviews,” section 3.1.6., “Factor 6--Feed Tank Sampling,” section 3.2.2., “Waste 

Sampling,” and section 3.1.8, “Factor 8—Removal Efficiencies,” of the staff’s monitoring 

plan (NRC, 2007). 

2.2.1. Observation Scope 

NRC staff interviewed DOE and DOE contractor staff on topics related to liquid waste 

sampling and tracking of the radionuclide inventory transferred to the SDF during this onsite 

observation visit. The purpose of the interviews was to better understand and evaluate the 

methods used by DOE to quantify the inventory of radionuclides in liquid waste that is 

transferred to the SDF. This review was performed as part of the evaluation of Factor 6, 

Feed Tank Sampling, and Factor 8, Removal Efficiencies, identified in the NRC monitoring 

plan (NRC, 2007). Adequate characterization of the liquid waste transferred to the SDF is 

important because the total inventory of radionuclides disposed of in the SDF affects 

whether the performance objectives of 10 CFR 61.41 can be met. The methods used for 

waste sampling and tracking of the radionuclide inventory transferred to the SPF/SDF were 

previously reviewed during the October 2007 and March 2008 onsite observation visits. 

2.2.2 Observation Results 

DOE contractor staff provided an explanation of the data and assumptions that are used to 

prepare quarterly Saltstone Permit Reports that are available on the DOE Savannah River 

Operations Office website. This included an explanation of how information from a 

Tank 50 material balance worksheet, and other supporting information, is used to estimate 

volume weighted concentrations of radionuclides that are sent to the SDF each quarter. 

NRC staff asked why quarterly totals of radionuclides in grout (calculated by multiplying the 

total amount of grout reported in the Saltstone Permit Reports by the volume weighted 

average concentration in grout reported for each radionuclide) did not match quarterly 

totals of radionuclides in liquid waste (similarly calculated by multiplying the total amount of 

liquid salt waste solidified at the SDF by the volume weighted average concentration in 

liquid salt waste reported for each radionuclide). DOE contractor staff explained that total 

quantities of grout reported in the Permit Reports include grout used to form cold caps, and 

that bleedwater and flushwater from the SDF and SPF, respectively, are seen by a grout 

line flow transmitter as “grout,” even though these transfers would not add radionuclides to 

the SDF. As a result, the reported liquid salt waste concentrations and volumes are 

considered by DOE to be a more reliable basis for estimating quarterly radionuclide 

inventory in the SDF. In addition, DOE staff stated that the quarterly concentrations 

reported for the radionuclides that have “limits” set for them in the Saltstone WAC are 

based on volume weighted averages calculated based on the concentrations calculated in 
6 

the materials balance worksheet. However, the quarterly concentrations reported for the 

radionuclides that have “target” acceptance criteria are based only on the concentration 

measured in a semi-annual sample. 

NRC and DOE contractor staff also discussed how semi-annual Tank 50 confirmatory 

samples taken for measurements of radionuclide concentrations are used to adjust 

estimates of radionuclide inventory in Tank 50, which are more routinely updated using 

process knowledge and sampling results for influent liquid wastes to Tank 50. 

 

NRC staff plan to continue monitoring the inventory of radionuclides being added to the 

SDF. DOE agreed to provide additional information that NRC staff plan to review, including 

documentation, such as the materials balance worksheets, that supports the calculations 

used to derive the inventory estimates provided in quarterly Saltstone Permit Reports from 

the third calendar quarter of 2007 through the second quarter of 2008. DOE will also 

evaluate Tank 50 sample results vs. the Tank 50 material balance to verify that the 

materials balance is able to accurately estimate the concentration of radionuclides in 

Tank 50. Observation participants also discussed ongoing operations under the ARP/MCU 

management control plan (MCP). Under the MCP, DOE continues to sample and hold 

each batch of salt waste to be processed by the ARP/MCU, pending results of sample 

analysis. Ultimately, DOE intends to change to a “sample and send” mode of operation, 

wherein waste is processed, even while sample results are pending. The “sample and 

send” mode will enable DOE to increase waste treatment throughput. DOE also is 

considering developing a statistical basis for sampling less frequently than every 

microbatch. 

DOE Follow-up Actions

3. Provide sufficient documentation to support quarterly Saltstone Permit Reports for the 

 period from third quarter 2007 through second quarter 2008. 

4. Provide evaluation of Tank 50 material balance, from third quarter 2007 to present. 

5. Inform NRC when DOE is ready to exit its ARP/MCU management control plan. 

2.2.3 Conclusions and Followup Actions 

There are no new open issues or recommendations resulting from staff observations at this 

time. DOE follow up actions are listed above. 

2.3 Ongoing NRC Staff Technical Reviews 

NRC staff continues to monitor the quality of saltstone grout and vault concrete, as 

described in section 3.1.2., “Factor 1—Oxidation of Saltstone,” and section 3.1.3., “Factor 2 

- Hydraulic Isolation of Saltstone,” and section 3.1.4, “Factor 3 – Model Support,” of the 

staff’s monitoring plan (NRC, 2007). 
7 

2.3.1 Observation Scope 

Observation participants discussed 10 of 14 technical reports provided to NRC staff since 

November 2008. The reports are listed in Table 1 below. 

Table 1. Ongoing NRC staff technical reviews 

No. Description ADAMS 

Accession No. 

1 

Rosenberger, K. H., Comparison of Vault 4 Soil Sampling Results 

to Existing Unreviewed Disposal Question Evaluation 

SRS-REG-2007-00041, SRNS-J2100-2008-00013, Savannah 

River Nuclear Solutions. December 3, 2008

ML090120429 

2 

Kubilius, W., Z-area Vault 4 Phase 2 Soil Sample Analytical Data 

Report, ERD-EN-2008-0083, Savannah River Site, 

December 2008. 

ML090120404 

3 

Rosenberger, K. H., Unreviewed Disposal Question Evaluation: 

Evaluation of Liquid Weeping from Saltstone Vault 4 Exterior Walls, 

SRS-REG-2007-00041, Revision 1, Westinghouse Savannah River 

Company, Aiken, South Carolina, April 2008. 

ML090120475 

4 Kent, E., Letter to J. Buczek, WSRC, re: Samples received on 

February 14, 2008, GEL Laboratories, March 13, 2008. 

ML090120546 

5 Kent, E., Letter to J. Buczek, WSRC, re: Samples received on 

July 16, 2008, GEL Laboratories, September 16, 2008. 

ML090120539 

6 

Kaplan, D. I., K. Roberts, J. Coates, M. Siegfried, S. Serkiz, 

Saltstone and Concrete Interactions with Radionuclides: Sorption 

(Kd), Desorption, and Reduction Capacity Measurements, SRNSSTI-2008-00045, Savannah River National Laboratory, WSRC. 

October 2008 

ML090150234 

7 

Dixon, K., J. Harbour, and M. Phifer, Hydraulic and Physical 

Properties of Saltstone Grouts and Vault Concretes, 

SRNL-STI-2008-00421, Revision 0, Savannah River National 

Laboratory, WSRC. November 2008 

ML090150298 

8 

Langton, C., Evaluation of Sulfate Attack on Saltstone Vault 

Concrete and Saltstone, Part I: Final Report, SRNS-STI-2008-

00050, Revision 0, Savannah River National Laboratory, SRNS. 

August 19, 2008 

ML090150306 

9 

Langton, C., Evaluation of Sulfate Attack on Saltstone Vault 

Concrete and Saltstone, Part II: Test Methods to Support Moisture 

and Ionic Transport Modeling using the STADIUM® Code, SRNSSTI-2008-00052, Revision 0, Savannah River National Laboratory, 

SRNS. August 19, 2008 

ML090150312 

14 

Dixon, K., J., Video Survey of Saltstone Vault 4, Cell G, SRNLESB-2008-00017, Savannah River National Laboratory, WSRC. 

April 25, 2008 

ML090150154 

2.3.2 Observation Results 

Summaries of the technical review discussions, including follow-up actions by DOE, are 

provided below.
8 

Vault 4 soil sampling 

Reports 1-5 listed above pertain to studies of soil contamination that occurred outside of 

Cell E of Vault 4 at the SDF as a result of active weep sites in the exterior vault wall. Of 

particular interest to NRC staff is the concentration of iodine-129 that was observed in one 

sample, as described in Section 4.3 of Report 2. The reported iodine-129 concentration in 

a phase 2 gravel sample from 3” to 12” in depth next to Cell E was 69 pCi/g (a 95 percent 

confidence interval, or uncertainty value, was not reported). The cesium-137 value for the 

corresponding phase 1 sample from the same depth and location was 11,700 pCi/g. 

Using these values, staff calculated a concentration ratio of Cs-137 to I-129 of about 170. 

Using expected SDF inventories cited in the salt waste performance assessment 

(DOE, 2005), the expected average Cs-137:I-129 ratio in salt waste is about 75,000. NRC 

staff believes that the reasons for the large difference between an expected Cs-137:I-129 

ratio of 75,000 and an observed ratio of 170 should be thoroughly understood by DOE. 

DOE believed that the data suggest no further sampling was needed for I-129, however, 

the NRC staff did not agree with this assessment based on the current information. The 

staff believes that further understanding of the differences may be derived from studying 

the waste that was being added to Cell E (which perhaps had a substantially different ratio 

of Cs-137:I-129 than that of the expected long-term average concentration of salt waste), 

or in terms of natural processes that may have governed the ratio of Cs-137:I-129 in the 

soil. 

NRC staff also asked whether DOE had considered sampling under footers at the base of 

the Vault south wall, in order to test whether the floor of the vault may also have active 

weep sites. DOE explained that the causes of the discontinuities in construction that 

resulted in active weep sites in the vault walls are not anticipated in the floor of the vault, 

and believes that no sampling below the footers is necessary. Downgradient groundwater 

monitoring will continue to be relied upon to ascertain whether contamination from active 

weep sites, or any other potential sources, is migrating away from Vault 4. NRC staff 

commented that valuable lessons can be learned by the observed distribution of 

contamination in the subsurface, and that those lessons should be applied to revisions of 

the performance assessment. 

DOE Follow-up Actions

6. DOE should continue to investigate the source of iodine-129 detected in soil samples. 

Sorption (Kd), Desorption, and Reduction Capacity Measurements

Report 6 provides the results of research on sorption, desorption, and reduction capacity 

measurements that were performed on laboratory-prepared samples of saltstone grout and 

vault concrete. DOE explained that data from this report will be used in its update of the 

salt waste performance assessment. Of particular interest to NRC staff, are the results for 

sorption (Kd) and desorption of technetium-99 in this report. The Kd values obtained for 

technetium in these experiments were significantly less than the values assumed in the 

performance assessment, indicating that it would be significantly more mobile than 

assumed in the performance assessment. Additionally, technetium was apparently not 

reduced in the experiments described in this report. NRC staff recognizes that the purpose 

of these experiments was to determine the transport of technetium through the saltstone 

vault rather than the ability of saltstone to immobilize technetium during curing. However, 
9 

because the technetium did not become reduced in the presence of saltstone, staff 

requested additional information about the basis for DOE’s confidence that technetium in 

salt waste would be reduced as saltstone grout cures. 

During the observation, DOE explained that while there is currently no experimental basis 

that specifically supports DOE’s assumption that technetium-99 in salt waste will be 

reduced, and thereby retained, in the current saltstone grout formulation, DOE plans to 

perform additional experiments that will be designed to support such an assumption later 

this year. Given the risk significance of this assumption in DOE’s performance assessment 

(DOE, 2005), this is a new open issue under Section 3.2.4 of the NRC monitoring plan 

(NRC, 2007). 

Open Issue 2009-1

At the SRS Saltstone Facility, DOE should demonstrate that (1) technetium-99 in salt waste 

is converted to its reduced chemical form in saltstone grout during the curing of saltstone 

grout, and is thereby strongly retained in saltstone grout, and (2) the sorption of dissolved 

technetium-99 onto saltstone grout and vault concrete is consistent with Kd values for 

technetium-99 that were assumed in the performance assessment. 

DOE Follow-up Actions

7. Explain what measures were taken to ensure that experiments with technetium were 

not affected by experimental losses, such as technetium holdup in labware, resulting in 

underestimates of technetium concentration. 

8. Clarify the pH of the calcite solution used in these experiments (page 9 and 16 state 

the pH = 10; page 7 states that solution pH = 8.3). 

9. Clarify the selenium Kd value reported in Table 5, which is different than the value 

reported previously in the report. 

Hydraulic and Physical Properties of Saltstone Grouts and Vault Concretes

Report 7 provides the results of research on physical properties of laboratory-prepared 

samples of saltstone grout and vault concrete. NRC staff noted that material porosity 

measurements were as expected, but that the saturated hydraulic conductivity 

measurements for both saltstone grout and vault concrete and the porosity of saltstone 

were much higher than expected. Higher saturated hydraulic conductivity would be 

expected to lead to higher water flow rates, and higher associated degradation of saltstone 

grout and vault concrete than calculated in the salt waste performance assessment. NRC 

staff expressed the concern that the wasteform properties are one of the key components 

to mitigating risk from saltstone, and that inferior hydraulic properties are likely correlated 

with inferior diffusivity, which can impact long-term durability. NRC staff asked how the 

new measurement information will be incorporated into the performance assessment. 

DOE stated that it compares the information to sensitivity cases, and the new information 

would be reflected in the new performance assessment. The annual regulatory report 

identifies new information and identifies when the performance assessment needs to be 

updated. NRC staff indicated that the new information on hydraulic and physical properties 

could impact other activities, such as degradation assessments. DOE indicated that an 
10 

integration team helps to ensure that new information is reflected in other products. NRC 

staff inquired about the status of implementation of the Saltstone Product Quality Plan. 

DOE indicated they would provide a status of implementation and may update analysis 

after it is fully implemented. 

NRC staff discussed the measurement of moisture characteristics curves. The report 

provided recent measurements for saltstone and vault concrete that were substantially 

different than similar measurement completed by the Idaho National Laboratory (INL). 

NRC staff discussed how the data were going to be used and interpreted. DOE indicated 

that they had planned to use the data from INL and they had not performed an evaluation 

of the impact of different moisture characteristic curves. NRC staff indicated that the 

moisture characteristics curves can have a large impact on projected waste release rates, 

and if there is significant uncertainty or variability in the values that the uncertainty and 

variability should be evaluated in the performance assessment. 

DOE Follow-up Actions

10. Clarify whether bleedwater was leaking from sealed containers during the hydraulic 

properties study, when the report indicated the samples were sealed. 

11. Clarify the impact of changing pore solution concentration on measured hydraulic 

properties on page 8 of Report 7. 

12. Explain how uncertainty will be addressed for moisture characteristic curves that are fit 

to data reported on page 18 of Report 7. 

13. Justify the use of logarithmic averages for recommended hydraulic property values on 

p. 19. 

NRC also requested additional information about the results of physical or chemical tests 

being performed on core samples that were taken from three locations along the western 

wall of Cell E of Vault 4 in September 2008. Each core was approximately 3 to 4 inches in 

diameter and 6 inches deep. DOE explained that it is planning laboratory studies that may 

begin during the third quarter Fiscal Year 2009, in which it will test porosity, saturated 

hydraulic conductivity, and distribution coefficients for radionuclides. NRC staff will follow 

up on DOE’s progress in preparing experiments for these core samples in future monitoring 

activities. A representative from the South Carolina Department of Health and 

Environmental Control suggested that it would be very useful to perform leaching studies of 

the saltstone core samples, and NRC staff agreed. 

Video Survey of Vault 4, Cell G 

Observation participants watched a video survey of Cell G in Vault 4 (Report 14). The 

video showed fractures on the surface of the saltstone. Of particular interest was a large 

aperture crack emanating from the north corner of Cell G. This crack propagates out from 

the corner at approximately a 45 degree angle and appears to extend entirely across the 

cell. Staff also noted, as stated in Report 14, that there is no obvious separation between 

the vault wall and saltstone associated with shrinkage of the saltstone grout. The surface 

of the saltstone appeared to be rough and contained areas of darker color. DOE explained 

that the roughness was attributed to dripping condensation during curing and the dark 
11 

spots were attributed to corrosion of steel in the vault roof that dripped onto the surface of 

the saltstone. Staining along one of the cracks likely indicated that water contained 

corrosion products collected and flowed into the fracture. NRC staff noted that the 

fractures do not appear to be extensive, but that conclusion was hindered by lack of scale 

and a limited survey area. DOE plans to do more surveys in the future. 

Evaluation of Sulfate Attack on Saltstone Vault Concrete and Saltstone 

Observation participants discussed NRC staff questions on Reports 8 and 9. 

DOE Follow-up Actions

14. Provide up-to-date copy of the PA maintenance plan 

15. Evaluate the sensitivity of grid spacing to predicted front propagation in the sulfate 

attack evaluation. 

16. Explain how spatial representation in the numerical experiments of sulfate attack will be 

translated into a PA model, since the geometries of the real system will be much more 

complex (e.g., a random collection of different size blocks determined by crack 

distributions) than those considered in the numerical experiments. 

17. Explain how cracks are incorporated into the sulfate attack representation in the PA 

model, since cracks could significantly impact the degradation assessment (page 15). 

Explain assumption I that the transport rate through damaged concrete of sulfate ions 

is not different from undamaged concrete (page 21). 

18. Clarify the conceptual model for sulfate attack. For example, does sulfate attack 

proceed along a front, or is it a generalized mechanism 

19. Clarify the conceptual model represented by case 2 (page 6). If the concentration was 

diluted by diffusion, then what is the fate of diffused species? If species are diffusing 

through the vault wall, then why isn’t the vault wall degraded. 

20. Explain why it is appropriate to neglect minor species (page A2-14). 

21. Justify the use of Berner’s approach for these materials and solutions (page A2-15). 

2.3.3 Conclusions and Followup Actions 

There are no recommendations resulting from staff observations at this time. 

There is one new open issue regarding whether: (1) technetium-99 in salt waste is 

converted to its reduced chemical form in saltstone grout during the curing of saltstone 

grout, and is thereby strongly retained in saltstone grout, and (2) the sorption of dissolved 

technetium-99 onto saltstone grout and vault concrete is consistent with Kd values for 

technetium-99 that were assumed in the performance assessment. 

DOE follow up actions are listed in section 2.3.2 above. 
12 

3.0 PARTICIPANTS 

U.S. NRC

David Brown 

Nishka Devaser 

David Esh 

Chris Grossman 

Christepher McKenney 

Karen Pinkston 

Gregory Suber 

SCDHEC

Byron Amick 

K. Leigh Beatty 

John McCain 

Ted Millings 

Barry Mullinax 

Jason Shirley 

Josh Yon 

U.S. DOE

Jeff Bentley 

Jim Folk 

Tom Gutmann 

Martin Letourneau 

Bill Levitan 

Chun Pang 

Sherri Ross 

Pat Suggs 

Linda Suttora 

Armanda Watson 

WSRC

Doug Bumgardener 

Seth Campbell 

Ginger Dickert 

Victor Franklin 

Eric Harrison 

Keith Liner 

Bruce Long 

Dave Olson 

Larry Romanowski 

F. Malcolm Smith 

Aaron Stauts 

SRNS

Kent Rosenberger 

BSRI

 Bernie Eneroldsen 

4.0 REFERENCES 

U.S. Department of Energy (DOE). DOE-WD-2005-001, “Basis for Section 3116 Determination 

Salt Waste Disposal at the Savannah River Site.” Washington, DC: DOE. March 2005a. 

–––––. CBU-PIT-2005-0146, “Saltstone Performance Objective Demonstration Document.” 

Westinghouse Savannah River Company. June 2005b. 

–––––. DOE-WD-2005-001, “Basis for Section 3116 Determination Salt Waste Disposal at the 

Savannah River Site.” Washington, DC: DOE. January 2006. 

U.S. Nuclear Regulatory Commission (NRC). “Technical Evaluation Report for Draft Waste 

Determination for Salt Waste Disposal.” Letter from L. Camper to C. Anderson, DOE. 

December 28, 2005. (Agencywide Documents Access and Management System (ADAMS) 

Accession No. ML053010225). 

–––––. “U.S. Nuclear Regulatory Commission Plan for Monitoring the U.S. Department of Energy 

Salt Waste Disposal at the Savannah River Site in Accordance with the National Defense 

Authorization Act for Fiscal Year 2005.” Washington, DC: NRC. May 3, 2007. (ADAMS 

Accession No. ML070730363). 

–––––. “Nuclear Regulatory Commission Onsite Observation Report for the Savannah River Site 

Saltstone Production and Disposal Facilities, July 31, 2008.” July 31, 2008 (ADAMS Accession 

Number ML082530057). 

–––––. Construction Design Drawings of Cells 2A and 2B (Vault 2) at the Savannah River Site, 

Saltstone Facility.” Memorandum to Project File. May 12, 2009 (ADAMS Accession Number 

ML091400079).