January 31, 2008 

 

Lawrence T. Ling, 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 ONSITE OBSERVATION REPORT 

FOR THE SAVANNAH RIVER SITE SALTSTONE PRODUCTION AND 

DISPOSAL FACILITIES 

Dear Mr. Ling: 

The enclosed document describes the U.S. Nuclear Regulatory Commission=s (NRC=s) onsite 

observation activities on October 29-30, 2007, at the Savannah River Site (SRS), Saltstone 

Production Facility (SPF) and Saltstone Disposal Facility (SDF). This onsite observation was 

conducted in accordance with the Ronald Reagan National Defense Authorization Act for Fiscal 

Year 2005 (NDAA), which requires NRC to monitor disposal actions taken by the Department of 

Energy (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). 

NRC=s onsite observation at SRS was primarily focused 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 saltstone wasteform production 

and disposal operations, and verifying DOE=s radiation protection measures associated with 

those operations. Since saltstone wasteform production operations could impact 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. Additional 

visits will be conducted in the future to assess compliance with these and other performance 

objectives in 10 CFR Part 61, Subpart C. 

The enclosed report indicates that, during our visit, we were unable to obtain some information 

needed to fully assess whether current operations are consistent with assumptions made in the 

waste determination (DOE 2006) with respect to vault integrity and the characterization of the 

final saltstone wasteform. As such, we plan to conduct another onsite monitoring visit during the 

first quarter of 2008 to follow up on our observations regarding: 1) final product (wasteform) 

characterization; 2) impacts of the differences in observed conditions of Vault 4 with the waste 

determination; and 3) impacts on the final product properties of the intra-batch variations from 

flush water additions and additives used to ensure processability. The fact that NRC staff is 

requesting more information regarding these areas does not mean that the NRC has concluded 

that DOE disposal activities are not in compliance with 10 CFR 61, Subpart C, but rather that 

more information is needed to support DOE’s assumptions and approaches. We recognize that, 

consistent with NRC’s monitoring plan for the salt waste disposal facility, monitoring can be 

iterative and several onsite observation visits may be necessary in order to obtain all the 
L. Ling 2 

information needed to close an issue. During a conference call on January 28, 2008, between 

NRC and DOE, DOE indicated that some of the information requested by the NRC may be 

available and will be made accessible to the NRC at the next observation visit to SRS. If DOE 

would like to provide this information in advance of the next onsite observation visit, you may 

send it to us, and we will evaluate it. 

On October 30, 2007, at the conclusion of the onsite observation activities, members of my staff 

discussed the topics addressed in this report with you and members of your staff. If you have 

any questions or need additional information regarding this report, please contact Michael Fuller, 

Project Manager on my staff, at 301-415-0520. 

Sincerely, 

 /RA/

Scott Flanders, 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. Sherritt 

Federal Facilities Liaison 

Environmental Quality Control Administration 

South Carolina Department of Health 

 and Environmental Control 

2600 Bull Street 

Columbia, SC 29201-1708
L Ling 2 

information needed to close an issue. During a conference call on January 28, 2008, between 

NRC and DOE, DOE indicated that some of the information requested by the NRC may be 

available and will be made accessible to the NRC at the next observation visit to SRS. If DOE 

would like to provide this information in advance of the next onsite observation visit, you may 

send it to us, and we will evaluate it. 

On October 30, 2007, at the conclusion of the onsite observation activities, members of my staff 

discussed the topics addressed in this report with you and members of your staff. If you have 

any questions or need additional information regarding this report, please contact Michael Fuller, 

Project Manager on my staff, at 301-415-0520. 

Sincerely, 

 /RA/ 

Scott Flanders, 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. Sherritt 

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 

ML073461038 

OFC FSME/DWMEP FSME/DWMEP FSME/DWMEP FSME/DWMEP 

NAME M.Fuller A.Kock A.Bradford S.Flanders 

DATE 1/8/08 1/8/08 1/17/08 1/31/08 

OFFICIAL RECORD COPY
SAVANNAH RIVER SITE SALTSTONE PRODUCTION AND DISPOSAL FACILITIES 

NRC ONSITE OBSERVATION REPORT 

EXECUTIVE SUMMARY 

NRC staff conducted its first onsite observation visit of the Saltstone Production Facility (SPF) 

and Saltstone Disposal Facility (SDF) at the Savannah River Site (SRS) on October 29-20, 

2007. 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 operationsCby observing DOE saltstone wasteform production 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. 

NRC staff evaluated the implementation of the grout quality assurance program, the construction 

of the vault, the waste sampling program, the radiation protection program, and also reviewed 

pertinent records. NRC staff observed operation of the SPF and toured the SDF (Vault 4), and 

interviewed key SRS and contractor personnel. NRC staff observed activities and reviewed data 

collected to assess consistency with assumptions made in the waste determination (DOE, 

2006). 

Grout Formulation and Placement 

$ The observation determined that the quality assurance program of DOE and its 

contractor is effective. NRC staff also determined DOE has a program for verifying that 

the grout components conform to applicable American Society for Testing and Materials 

(ASTM) standards. NRC recommended that DOE consider performing independent 

verification of vendor material characterization. 

$ Additional information beyond that supplied with the performance assessment and 

supporting documentation provided with the waste determination was not available 

during the monitoring visit to support the physical characteristics of the saltstone 

wasteform. Current characterization processes, as described to NRC by DOE during the 

monitoring visit, does not allow for a verification of physical properties assigned in the 

final waste determination. Final product characterization is an open issue because 

inadequate quality of saltstone could result in the disposal of saltstone being noncompliant with the 61.41 performance objective. 

$ Additional information is needed on the impact on the properties of the final product from 

potential intra-batch variability in bulk components, flush water additions, and additives 

used to ensure processability. Inadequate quality of saltstone could result in the disposal 

of saltstone being non-compliant with the 61.41 performance objective; therefore this is 

an open issue that NRC will follow up on during future monitoring activities. 
2 

Vault Construction 

• The observation determined that DOE has taken action in an attempt to mitigate the 

impact of previously identified vault construction defects (e.g., cracking) on facility 

performance. However these efforts have not been fully effective as contaminated 

seeps were noted while observing the current cell of Vault 4 being filled. The 

observation determined that DOE appropriately characterizes and manages the 

contamination. The level of contamination measured on the outside of the vault does 

not pose an immediate health and safety concern to workers or the public. The area is 

maintained as a radiologically controlled area but workers or authorized visitors can 

safely walk next to the vaults. 

$ NRC was unable to determine that DOE has assessed the risk significance of the impact 

of differences in observed conditions of the vaults to conditions assumed in its final 

waste determination and performance assessment (PA). If the quality of the saltstone 

wasteform proves to be inadequate, failures of the SDF vaults to adequately contain the 

waste, could result in the disposal of saltstone being non-compliant with the 61.41 

performance objective. Therefore, this is an open issue that NRC will follow up on during 

future site monitoring activities. 

Waste Sampling 

$ The observation determined that DOE’s procedures used to characterize the waste in 

Tank 50, the feed tank to the SPF, appeared to be adequate to determine the inventory 

of radionuclides that are sent to the SPF, and ultimately to the SDF. However, NRC staff 

plans to examine sampling activities and results in more depth, during future monitoring 

visits. Therefore, this is an open issue that NRC will follow up on during future 

monitoring activities. 

$ NRC recommends that DOE either confirm that the build up of solids be readily identified 

during processing or take actions to mitigate such build up. Therefore, this is an open 

issue that NRC will follow up on during future monitoring activities. 

Radiation Protection Program 

$ The observation determined that DOE has an adequate program for protecting its 

personnel and the public from radiation exposures during operations at the SPF and 

SDF. Although the review resulted in no open issues, NRC will continue monitoring 

activities related to radiation protection during future onsite observation visits to SRS. 

1.0 BACKGROUND 

The National Defense Authorization Act for Fiscal Year 2005 (NDAA) authorizes the DOE, in 

consultation with the NRC, to determine that certain radioactive waste related to the 

reprocessing of spent nuclear fuel is not high-level waste, provided certain criteria are met. The 

NDAA also requires NRC to monitor DOE disposal actions to assess compliance with the 

performance objectives in 10 CFR Part 61, Subpart C. 
3 

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

Savannah River Site” to demonstrate compliance with the NDAA criteria including demonstration 

of compliance with the performance objectives in 10 CFR Part 61, Subpart C. In its consultation 

role, the NRC staff reviewed the draft waste determination and concluded that there was 

reasonable assurance that the applicable criteria of the NDAA 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. DOE issued a 

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

conclusions, and recommendations documented in NRC’s TER. 

To carry out its monitoring responsibility under the NDAA, NRC plans to perform three types of 

activities focusing on key assumptions, called “factors” identified in its monitoring plan for 

saltwaste disposal at SRS (NRC, 2007): (i) technical reviews, (ii) onsite observations, and (iii) 

data reviews. Technical reviews generally will focus on obtaining additional model support for 

assumptions DOE made in its PA that are considered important to DOE's compliance 

demonstration. Onsite observations generally will be performed to (i) observe and review data 

collected to assess consistency with assumption made in the waste determination (e.g., 

observation of waste sampling used to generate data on radionuclide inventories) 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 focusing on real-time monitoring data that may also indicate future 

system performance or review of records or reports that can be used to directly assess 

compliance with performance objectives. 

NRC=s October 2007 onsite observation at SRS was 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 operations at the 

SPF and SDF, and verifying DOE=s radiation protection measures there. 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. Additional 

visits will be conducted in the future to assess the performance objective in 10 CFR 61.42, 

protection of individuals against inadvertent intrusion, and to continue assessing DOE 

compliance with the other performance objectives. 

2.0 NRC ONSITE OBSERVATION ACTIVITIES 

2.1 Grout Formulation and Placement 

2.1.1. Observation Scope 

The observation of DOE saltstone production and disposal operations is related to Factor 1 -

“Oxidation of Saltstone”, and Factor 2 - “Hydraulic Isolation of Saltstone” identified in the NRC 

monitoring plan for the SRS SPF and SDF (NRC, 2007). The general objectives of NRC 

monitoring activities related to Factor 1 and Factor 2 are to ensure that the saltstone that is 

produced is of sufficient quality such that there is reasonable assurance that the performance 

objectives of 10 CFR Part 61 will be achieved. As discussed in the NRC TER for review of salt 

waste disposal at the SRS, the hydraulic and chemical properties of the wasteform are important 

for isolating the radioactivity contained in the waste from the environment (NRC, 2005). A 
4 

specific objective of the monitoring visit was to ensure that the saltstone formulation produced in 

the SPF and emplaced in the SDF is consistent with the design specifications assumed in the 

final waste determination [DOE Savannah River Site (DOE-SRS, 2006)], or that significant 

deviations from design specifications will not negatively impact the expected performance of the 

wasteform. Staff also attempted to obtain information that DOE has collected to further evaluate 

uncertainties (discussed in the NRC TER). 

2.1.2 Observation Results 

NRC staff observed ongoing saltstone facility operations at SRS. NRC visited the SPF and 

observed the preparation of saltstone grout components and placement into the vault. 

Preparation of saltstone at the SPF is remotely controlled by a group of operators in the control 

room using a digital control system (DCS). NRC observed the mixing of the saltstone wasteform 

and transfer of the grout mixture from the SPF to the SDF via video cameras located in the plant 

and vault and displayed in the control room. DOE staff indicated that the plant is able to fill a 

vault cell at the rate of approximately 4 cm per hour for an approximately 0.3 m per daily shift lift 

in a vault cell. 

NRC staff observed the bins used to store the dry slag and cementitious materials prior to mixing 

with dissolved salt waste. The bins appeared adequate for preventing precipitation from 

contacting the grout materials to minimize the degradation in the quality and chemical reactivity 

of the slag and Portland cement. The grout materials include blast furnace slag, fly ash, and 

Portland cement which are delivered by truck to the saltstone bins and are mixed in a 45-wt% 

slag, 45-wt% fly ash, and 10-wt% Portland cement formulation. NRC staff reviewed sample 

quality assurance records and verified that the received grout materials had certified chemical 

and physical test reports that are based on ASTM standards (e.g., ASTM C 989 for blast furnace 

slag, ASTM C 618-03 for fly ash, and ASTM C 150 for Portland cement). A review of 

representative test reports indicated the received materials conformed to the standards. 

NRC staff also verified that the measured sulfide sulfur content of the blast furnace slag supplied 

by the vendor is consistent with the quality assurance receipt inspection procedures supplied by 

DOE staff during the observation visit. The amount of sulfide in the slag is important because it 

imposes a reducing condition on the grout that helps mitigate the release of Tc-99. The 

measured sulfide sulfur content should be greater than 0.6 wt% by inspection procedure but less 

than 2.5 wt% in accordance with ASTM C 989 requirements. Representative test reports were 

provided to verify that blast furnace slag content is within this range. However, it should be 

noted that all test reports were from the material vendor and other than the receipt inspection 

procedures conducted for each truckload of material, no confirmatory chemical analyses are 

conducted by DOE. Independent verification of the material characteristics would provide 

additional assurance of the product quality. 

Bulk material (slag, fly ash, cement) proportions are controlled by weighing the components. 

Target masses for each batch are 2700 lb fly ash, 2700 lb slag, and 600 lb cement. An alarm is 

activated if the component masses are +/- 300 lb from the targets. NRC staff observed a 

number of alarm notifications for masses deviating from the targets. These alarm notifications 

were verbally acknowledged between operators in the control room and were part of normal 

operations. The alarms are a warning to the operators to check the masses of the dry bulk 

materials being input to the process to ensure product composition specifications could be met 

and do not represent a failure of the process. The dry bulk materials were blended prior to 
5 

transfer to a hopper for mixing with salt waste in the SPF. DOE stated that the dry bulk materials 

have different particle size distributions and different flowability characteristics. DOE does not 

have a system to evaluate the relative proportion of the saltstone components within a batch 

once mixed with salt waste, although as stated above they do have a system to verify the total 

quantity of dry bulk materials input to a batch. However, product quality was evaluated when the 

facility was initially placed into operation (e.g., cold “non-radioactive” samples were produced 

using surrogate waste streams and were characterized for bulk properties such as strength). 

Toxicity Characteristics Leaching Procedure (TCLP) tests were previously completed over a 

range of compositions; however, as previously noted in the TER, DOE has not generated 

hydraulic and chemical properties of saltstone over a similar range of compositions (NRC, 2005). 

 No additional data on the hydraulic and chemical properties of saltstone was available at the 

time of the monitoring visit. Additional data on the hydraulic and chemical properties of saltstone 

will greatly reduce the uncertainty in estimating future performance of the SDF. 

Salt waste is sent from Tank 50 to a feed tank at the SPF. The feed tank has a mixer that can 

be operated only when the pump used to transfer salt waste to the blending system is not in 

operation. Waste that has been processed to date has not had a significant amount of solids. 

However there may be the potential for buildup of solids in the feed tank with current mixing and 

mobilization systems. If solids build up were to occur, it could impact wasteform composition. 

Solids buildup could result in additional radiological exposure to workers if new systems need to 

be used to mobilize the solids. NRC recommends that DOE either ensure that solids build up 

can be clearly identified during processing or take actions to mitigate the potential for solids build 

up. 

The specification for the water (salt solution) to cement (dry components) ratio is 0.6. Set 

retardant (0.3 gpm) and anti-foam agents (0.1 gpm) are added to the dry components and salt 

waste to facilitate processing. After blending of salt waste and the dry components in the SPF, 

saltstone is transferred to the SDF where it is emplaced in the vaults through fill pipes. 

Temperatures within the vault and saltstone are measured with thermocouples. Temperatures 

are limited to 85 C and the maximum observed temperature has been approximately 50 C. 

Relative humidity is not monitored within the disposal cells, which is noted as a limitation of the 

system but is not otherwise expected to impact final product quality. During cold weather, a 

significant quantity of condensation has been observed within the cells. Visual inspection of the 

final wasteform is completed to a limited degree; however condensation limits the ability to 

conduct remote visual inspections. NRC staff inquired, but no still or video images were 

available for staff review. At the end of a production run (typically at the end of a work day), the 

system is flushed with approximately 1200 gallons of water. The flush water is sent directly to 

the saltstone vault in use for the production run. The ultimate disposition and impact of the flush 

water on the final product was not known by DOE. If the flush water blends with the saltstone 

that has not yet set in the SDF, the water cement ratio of this portion of the product would be 

much higher than that assumed in the waste determination. Very high water to cement ratios 

could result in the affected fraction of the saltstone wasteform having inferior hydraulic 

properties. Based on processing rates and current system operation, it is estimated the fraction 

of saltstone that may be impacted by high water to cement ratio is less than 5 volume percent. 

During the monitoring visit, no additional information was provided to characterize the hydraulic 

and chemical properties of the final product emplaced within the SDF (e.g., core or other 

samples). As discussed in Section 2.2.2, the hydraulic properties of the vaults are not likely to 

be consistent with the assumptions in the waste determination. Because the vaults were 
6 

envisioned to provide secondary containment, a less robust secondary containment places more 

burden on the primary containment (i.e. saltstone) to provide the degree of isolation assumed in 

the waste determination. In addition, the implied deviation of the observed properties of the 

vaults highlights the difficulty of achieving in the field the properties observed in laboratory 

samples or in analogous facilities. No information to verify the properties of saltstone emplaced 

in the SDF was available for the NRC staff to review. DOE staff interviewed were not aware of 

any plans to characterize the emplaced saltstone. Information is needed from DOE to 

demonstrate that the hydraulic and chemical properties of the final product are consistent with 

the assumptions in the waste determination, or demonstrate that any deviations are not 

significant with respect to demonstrating compliance with the performance objectives. 

2.1.3 Conclusions and Followup Actions 

The NRC staff determined that the DOE quality assurance program pertaining to the 

specification of dry bulk materials is being effectively implemented. However, considering the 

importance of reducing capacity of saltstone to achieving the 61.41 performance objective, DOE 

should consider performing independent characterization of the slag upon receipt of the material 

rather than relying upon the vendor’s documentation. 

Records indicate the saltstone components conform to ASTM standards and the wasteform 

formulations are consistent with the assumed composition in the waste determination, with one 

exception. As discussed in Section 2.1.2, system flushing at the end of a production run likely 

results in a portion of the saltstone having a much higher water to cement ratio than assumed in 

the waste determination. NRC staff will follow up on this issue during future monitoring visits. 

Current DOE effort has been focused on process implementation and control. Although physical 

properties of saltstone (hydraulic conductivity and diffusivity) were identified as the most 

sensitive parameters in the analysis supporting the waste determination, DOE has not 

completed final product characterization nor were any plans to complete characterization of the 

final product provided during the observation. Intra-batch variability in product composition is not 

characterized. As discussed in Section 2.2.3, the observed quality of the secondary 

containment (the SDF vaults) is not as effective as previously assumed. Verifying the quality of 

the saltstone wasteform is important to ensuring that the 61.41 performance objective will be 

satisfied. Final product characterization is identified as an open issue that will be evaluated 

during future site visits. NRC staff intends to return to SRS, in the first quarter of 2008, to 

observe future saltstone production, characterization, and disposal operations, and follow up on 

the issues identified above. 

2.2 Vault Construction 

2.2.1. Observation Scope 

The observation of DOE saltstone disposal operations is related to Factor 1 -“Oxidation of 

Saltstone”, and Factor 2 - “Hydraulic Isolation of Saltstone” identified in the NRC monitoring plan 

for the SRS SPF and SDF (NRC, 2007). The reinforced concrete vaults of the SDF were 

assumed in the DOE waste determination to provide secondary containment for the radioactivity 

contained in saltstone and to limit the exposure of the saltstone wasteform to aggressive 

environmental conditions. A specific objective of the monitoring visit was to observe the 

saltstone disposal vaults to ensure that the assumptions regarding vault performance in the 
7 

waste determination were valid. Because the vault currently in operation was previously 

constructed, construction of the vault was not observed by NRC staff. 

2.2.2 Observation Results 

A number of problems were observed with vault performance during early operations by DOE. 

Cell A of Vault 4 had bulging, primarily at the bottom of the vaults, and weep sites where 

contamination was observed on the exterior surfaces of the vaults. These problems were 

discussed in detail in a variety of DOE reports and other forms of communication with State 

regulators [for example, an October 19, 2006 Letter from DOE to John McCain (DHEC)]. The 

primary mitigating action was to add a geotextile fabric membrane with an impervious backing to 

the vault walls. 

Although the currently used cells have the geotextile fabric and impervious backing on the 

interior walls, the vaults continue to have contaminated seeps that appear on the exterior 

surface of the vaults as they are filled with saltstone. NRC staff observed seeps on one wall of 

the vault currently being filled. The seeps appeared to be less than a meter in length. DOE 

stated that the seeps dry relatively quickly as the vaults are filled and the saltstone sets, sealing 

the fractures that are the source of the seeps. Information to indicate that the seeps are no 

longer active was not available at the time of the onsite observation visit. Because the seeps, if 

active, could influence the rate of release of radionuclides from the vaults, it is recommended 

that DOE quantify or provide information as to the degree of sealing of the fractures. One 

approach to evaluating whether the existing fractures are active would be to introduce water into 

inactive disposal cells and observe the resulting response of the vaults. Nondestructive 

techniques could also be used to quantify the status of the fractures. 

The area adjacent to the vaults is maintained as a radiologically controlled area. Contamination 

samples are taken of the seeps to characterize the amount of removable radioactive 

contamination. The area is roped off with appropriate signs and markers. 

NRC noted during the monitoring visit that DOE observed Cs-137 in the ditch adjacent to Vault 

4, Cell G [October 19, 2006 letter from DOE to John McCain (DHEC)], and that remedial action 

had been taken (e.g., contaminated soil was removed from the ditch). 

The vaults are intended to provide secondary containment for the radioactivity contained in 

saltstone and limit the exposure of the saltstone wasteform to aggressive environmental 

conditions. However, the current containment is not complete as assumed in the base case 

analysis supporting the waste determination [DOE, 2006]. The waste determination and 

supporting performance objective demonstration document assumed the hydraulic conductivity 

of the vault would be less than or equal to 1E-12 cm/s for 100 years after facility closure. The 

hydraulic conductivity of the saltstone was assumed to be 1E-11 cm/s over this time. The 

analysis increased the hydraulic conductivity in a stepwise manner over the 10,000 year 

performance period. The observation of seeps suggest that the vaults are of insufficient quality 

to achieve 1E-12 cm/s (which is representative of a very high quality concrete). DOE stated that 

the cracks (which result in the seeps) were attributed to the way the vaults were poured and 

cured. NRC previously documented the importance and relevance of the physical properties of 

the vaults and saltstone in the NRC TER documenting the review of the waste determination 

[NRC, 2005]. The hydraulic conductivity potentially affects the rate of release of waste from the 

facility as well as the degradation of the materials over time. During the onsite observation, DOE 
8 

stated they had not completed an evaluation to assess the impact of the observed condition of 

the vault on the waste determination (i.e., the difference between observed and assumed 

conditions). DOE plans to update the performance assessment supporting the saltstone waste 

determination in fiscal year 2009. Currently, DOE is envisioning a new vault design based on 

commercial water storage tank technology. 

The risk implications of the vault quality being less than assumed in the waste determination 

should be quantified by DOE with further analysis. However a summary of previous calculations 

can provide valuable risk context. DOE assumed that the complete saltstone inventory was in 

one vault for purposes of estimating the radiological impacts in the performance assessment 

supporting the final waste determination, even though it would actually be placed in up to 

fourteen vaults [DOE, 2006]. In addition, the peak whole body dose was estimated to be 

approximately 2.3 mrem/yr (compared to a 25 mrem/yr performance objective for 61.41). 

Therefore, there is margin for deviation from the assumptions in the final waste determination 

without DOE’s disposal actions being non-compliance with the performance objectives. 

However, lack of robust secondary containment places more importance on: 1) verifying the 

physical properties of the saltstone wasteform, and 2) ensuring that the saltstone is likely to be 

sufficiently resistant to degradation under anticipated future exposure conditions. In addition, the 

observation of the seeps suggests that the vaults should possibly be represented as sources of 

contamination in future performance assessment calculations rather than barriers to 

contamination. 

2.2.3 Conclusions and Followup Actions 

The NRC staff determined that the vaults provide adequate containment from a waste 

processing standpoint. That is, the vaults isolate the vast majority of the radioactivity in saltstone 

from the environment while the saltstone sets. However, quality issues previously identified by 

DOE continue to persist irrespective of mitigating actions. Seeps result in contamination 

reaching the exterior surfaces of the vaults. Based upon NRC staff observations, DOE appears 

to have appropriately characterized and managed the contamination such that it does not pose 

an immediate health and safety concern to workers or the public. 

The impact of the seeps on the long-term performance of saltstone will need to be quantified by 

DOE and reviewed by NRC. This is identified as an open issue that will be evaluated during 

future site visits. 

 2.3 Waste Sampling 

2.3.1 Observation Scope 

The objective of monitoring waste sampling is to evaluate the methodology used to quantify the 

inventory of radionuclides that is sent to the SDF. This review is being performed as part of the 

evaluation of Factor 6, Feed Tank Sampling, which was identified in the NRC monitoring plan 

(NRC, 2007). As stated in the monitoring plan, the total inventory of radionuclides disposed of in 

the SDF is an important part of meeting performance objectives of 10 CFR 61.41. Tank 50 in HTank Farm serves as the feed tank for transfers from the tank farms to the SPF and is the point 

of compliance for demonstrating that the waste meets the Saltstone Waste Acceptance Criteria 

(WAC) (Culbertson, 2007). As no sampling was ongoing at the time of the observation, the NRC 
9 

staff’s activities focused on reviewing DOE’s methodology for waste sampling and analysis. This 

was achieved by conducting interviews with site personnel and reviewing relevant documents. 

2.3.2 Observation Results 

As stated above, Tank 50 is the point of compliance for waste that is being transferred to the 

SPF and any waste transferred from this tank must meet the Saltstone WAC (Culbertson, 2007). 

 The Saltstone WAC ensures that waste entering the SPF is within the Documented Safety 

Analysis, Performance Assessment, and Operating Permitted values. The Tank 50 contents 

must remain in compliance with the Saltstone WAC when transfers to the SPF are occurring, 

though the WAC limits may be met either prior to the waste being transferred to Tank 50 or by 

blending of the waste with a lower concentration waste stream within Tank 50. 

The sampling plan for Tank 50 is documented in the “Sampling Strategy for Tank 50 Point of 

Compliance Transfers to Saltstone” (Ketusky, 2005). Samples are taken quarterly for chemical 

constituents and semi-annually for radionuclides. 

In addition, a sample is taken for both chemical and radiological contents for each salt batch. 

NRC staff discussed the methodology used to obtain samples from Tank 50 with site personnel. 

 The site personnel stated that samples from Tank 50 are taken from near the surface of the 

waste. Agitation pumps are run for several hours before the tank is sampled in order to ensure a 

representative sample and to ensure that particles in Tank 50 are adequately characterized. 

During sample collection, the pump nearest the location where the sample is being taken is shut 

down, but the other pumps continue to run. After the samples are collected, they are sent to a 

lab for quantification. A data integrity review is performed on the results of the analytical 

measurements prior to the acceptance of the data. In addition, samples are periodically sent to 

two different labs for quantification to evaluate the precision of the measurements. 

A materials balance is maintained for the radionuclides in Tank 50 in order to track the inventory 

in the tank in between when samples are taken. In this materials balance, all inputs to and 

outputs from the tank are tracked and this information is used to calculate the current conditions 

in the tank. After new sampling results are obtained, the materials balance is re-baselined to the 

values measured in the samples. 

In addition to transfers from other tanks in the tank farm, Tank 50 also receives waste streams 

from the general purpose evaporator and from Effluent Treatment Process (ETP) concentrate. 

Site personnel stated that these waste streams are required to meet the WAC for Saltstone 

before being transferred to Tank 50. Compliance with the WAC is demonstrated through 

periodic sampling of the waste streams and process knowledge. Waste streams were 

characterized initially through sampling, and periodic samples are taken to ensure that the 

assumptions regarding the system waste characterization have not changed. Site personnel 

stated that there was not a lot of variability observed in these waste streams over time. 

The tank farm waste currently in Tank 50 is from Tanks 23 and 49. The waste in these tanks 

has been characterized through sampling. Tank 49 contains salt waste resulting from the use of 

the Deliquification, Dissolution, and Adjustment (DDA) process on Tank 41 salt waste. In this 

process, salt cake in Tank 41 was dissolved and sent to Tank 49, and during this process it is 

possible for any sludge particles that are entrained in the salt in Tank 41 to be carried over to 

Tank 49. Tank 49 serves as a settling tank for these particles prior to the transfer of the Tank 41 
10 

salt waste to Tank 50. In order to ensure that radionuclide removal efficiencies were as 

expected during the DDA process, samples were taken at various depths in Tank 49 to verify 

that settling occurs and that the amount of particles transferred to Tank 50 is limited. Currently, 

the waste in Tank 50 is not being slurried during transfers to the SPF, so only supernate is being 

transferred. However, in the future, the agitation pumps will be run and the tank will be slurried 

during transfers to the SPF and any settled particles in Tank 50 will be transferred along with the 

supernate. 

2.3.3 Conclusions and Followup Actions 

NRC staff determined that the procedures used to assess the inventory of radionuclides in the 

feed tank that are sent to the SDF appeared to be adequate. No issues were observed with the 

methodology used to obtain samples from Tank 50 or from other inputs to Tank 50. In addition, 

the approach of only taking samples from Tank 50 twice a year and using a material balance to 

calculate the inventory in the tank may prove to be acceptable because DOE’s procedures call 

for characterization of the inputs to Tank 50. It is important for the inventory of radionuclides that 

is sent to the SPF to be based on sampling results instead of process knowledge when possible. 

Site personnel stated that waste transferred to Tank 50 from other tanks in the tank farms did 

not have to meet the WAC for Saltstone and that some credit could be taken for mixing with 

other waste streams. NRC staff believes that this approach is acceptable, but it is important for 

Tank 50 to be well mixed and for the waste that is sent to the SPF to meet the WAC prior to 

transfer. Problems could arise if transfers from Tank 50 to the SPF were to be made while Tank 

50 is receiving a significant transfer because mixing of the waste streams may not occur in the 

tank before the waste is removed. In addition, when the agitation pumps are turned on during 

transfer of waste from Tank 50 to the SPF, it is important to monitor the amount of solids in the 

waste to ensure that plugs of abnormally large concentrations of solids are not sent to the SPF. 

For example, if agitation pumps do not adequately suspend all particles, then there is the 

potential for higher concentrations of solids in the waste when the level of liquid in the tank is 

low. The potential for solids to build up in the Salt Feed Tank in the SPF also should be 

considered. During future monitoring visits, NRC staff plans to examine records relating to 

sampling activities as well as to examine sampling results in more depth. In particular, NRC 

staff plans to compare the analytical results from the samples to the inventories of radionuclides 

calculated in the materials balance to verify the accuracy of the materials balance calculations 

used to predict the concentration of radionuclides in Tank 50. NRC staff also plans to review the 

QA plans related to obtaining and analyzing samples in more detail. In addition, NRC staff plans 

to observe waste sampling activities during a future monitoring visit. More information on the 

site’s waste characterization methods, waste sampling quality assurance program, and 

confirmation that the measured radionuclide concentrations are as predicted is needed for 

closure of this monitoring activity. 

2.4 Radiation Protection Program 

2.4.1 Groundwater and Air Effluent Monitoring 

2.4.1.1 Observation Scope 

NRC staff interviewed DOE’s contractor environmental monitoring personnel and reviewed 

records of the environmental monitoring (EM) program pertaining to SDF Vault 4 (designated 
11 

“451-Z” in EM records) and the SPF stack (designated “210-Z building” in EM records). The 

staff focused specifically on the 2007 groundwater monitoring program results for three 

groundwater monitoring wells installed downgradient of Vault 4, and the 2007 air effluent 

monitoring program for the SPF stack and Vault 4. Staff toured the SPF and the vicinity of Vault 

4 to develop an understanding of the facility layout. The staff’s reviews were guided by Sections 

3.2.6 and 5.2.2 of the May 3, 2007, “U.S. NRC Plan for Monitoring the U.S. DOE Salt Waste 

Disposal at the Savannah River Site in Accordance with the National Defense Authorization Act 

for Fiscal Year 2005.” (NRC, 2007) 

2.4.1.2 Observation Results 

With regard to groundwater monitoring, NRC staff and DOE contractor personnel discussed the 

location of downgradient wells, sample collection methods, frequencies of sample collection, 

sample analysis, and recent sample results. NRC staff requested copies of and reviewed: (1) 

three procedures relating to groundwater monitoring well installation, sampling methods, and 

sample packaging (WSRC, 2006a, 2007a, 2007b); and (2) Revision 4 of the Groundwater 

Monitoring Plan for the Z-Area Saltstone Disposal Facility (WSRC, 2006b). The staff also 

reviewed preliminary sample results for calendar year 2007. 

NRC staff found no indication in the sampling results that potential monitored contaminants from 

Vault 4 have entered nearby groundwater. Of particular interest to NRC staff was the results for 

nitrate analysis, a major soluble component of the grouted wastes in Vault 4. The nitrate 

concentration in downgradient wells was similar to the nitrate concentration in the upgradient 

well. 

With regard to air effluent monitoring, NRC staff and DOE contractor personnel discussed the 

SRS program for demonstrating compliance with the requirements of 40 CFR Part 61, Subpart 

H, “National Emission Standards for Emissions of Radionuclides Other Than Radon From 

Department of Energy Facilities” at the SPF and the SDF (Vault 4). The DOE program for 

compliance with 40 CFR Part 61, Subpart H, an EPA rule, addresses the 10 mrem constraint on 

total effective dose equivalent (TEDE) to an individual member of the public cited in 10 CFR 

20.1101(d), which, in turn, is among the applicable portions of 10 CFR Part 20 that must be met 

for NRC to have reasonable assurance that the 10 CFR 61.43 performance objectives will be 

met during facility operation. DOE contractor personnel explained that processing of low curie 

salt (LCS) solution containing up to 0.2 curies per gallon is not expected to result in radionuclide 

emissions from the SPF due to the configuration of the blender and the screw-type mixer. 

Therefore, air effluent monitoring is only performed on air exhausted from Vault 4 during loading 

of LCS grout. NRC staff reviewed the basis for the type and frequency of air effluent monitoring 

at Vault 4 (SRS, 2005). Since the maximum effective dose equivalent (MEDE) and potential 

effective dose equivalent (PEDE) is less than 0.1 mrem/year, no control devices are used on the 

Vault 4 air effluent, and periodic quarterly sampling with offline analysis is performed during 

facility operations. 

NRC staff reviewed the preliminary 2007 air effluent monitoring data for gross alpha- and betaemitting radionuclides and specific radionuclides (cobalt-60, strontium-89/90, cesium-137, 

uranium-235/238, plutonium-238/239, americium-241, and curium-244). All monitoring results 

indicate that the public total effective dose equivalent remains below the 0.0816 millirem per 

year MEDE and PEDE calculated by contractor personnel, and well below the 10 CFR Part 

20.1101(d) constraint of 10 mrem TEDE per year. 
12 

2.4.1.3 Conclusions and Followup Actions 

During this observation visit, NRC staff reviewed sampling results for both the groundwater and 

air effluent monitoring programs at the SPF. NRC staff found that there is no indication of 

groundwater contamination in the vicinity of Vault 4 resulting from salt waste disposal 

operations. NRC staff also found that the air effluent sampling results for Vault 4 during filling 

operations indicate that doses to nearby workers and members of the public from air effluents 

remain well below applicable limits of 10 CFR Part 20 (i.e., the 10 mrem per year constraint on 

TEDE to the public). NRC staff plans to continue monitoring DOE environmental monitoring and 

surveillance programs at the SPF and SDF, for the foreseeable future, as an open activity under 

the NRC monitoring plan. 

2.4.2 Worker Dose Monitoring 

2.4.2.1 Observation Scope 

To verify that DOE=s radiation protection program is in place for operations at the SPF and the 

SDF to assess compliance with 10 CFR Part 61.43, protection of individuals during operations, 

the onsite observation included (i) interviews with DOE, and contractor radiation protection 

personnel; (ii) reviews of radiological control documents associated with saltstone operations, 

e.g., the SRS Radiation Control, and (iii) reviews of associated worker dose records. NRC staff 

toured the SPF and the SDF to verify the adequacy of access controls. 

2.4.2.2 Observation Results 

Through interviews with the F Tank Farm Manager and former Facility Manager for Saltstone, as 

well as other key site radiation protection personnel, and through reviews of pertinent personnel 

dosimetry records, NRC staff determined that SRS has an adequate radiation protection 

program. The NRC staff determined that the SPF and the SDF operations are controlled by 10 

CFR 835 and the SRS Radiation Control Manual (WSRC Manual 5Q, Radiological Control). 

There is no saltstone-specific radiation protection program. 

NRC staff reviewed personnel dosimetry reports for the 2nd and 3rd quarters of 2007. For 

approximately 150 individuals, the total quarterly person-rem were 40 mrem and 22 mrem, 

respectively, and quarterly radiation doses to individuals were predominately in the 0-3 mrem 

range. These doses are well within the dose limits in 10 CFR Part 835. It was during this 

timeframe that limited operations were ongoing at the SPF and the SDF similar to the operations 

observed during this visit. 

NRC staff also determined that there were no incidents involving personal contamination or loss 

of control of radioactive material during saltstone operations, year to date in 2007. 

Through interviews with key facility and radiation protection personnel, it was determined that 

there are adequate training and emergency response programs in place at SRS. 

2.4.2.3 Conclusions and Followup Actions 
13 

Through a review of the radiation protection program implemented by DOE at the SPF and the 

SDF, interviews with radiation protection personnel, and a tour of the facility, NRC staff 

determined that DOE has an adequate radiation protection program in place for SPF and SDF 

operations. No specific items were identified for followup, and there are currently no associated 

open items. NRC will continue monitoring activities related to radiation protection during future 

onsite observation visits to SRS. 

3.0 PARTICIPANTS 

NRC Observation Team 

David Brown 

David Esh 

Michael Fuller 

Lane Howard 

Andrea Koch 

Karen Pinkston 

Partial List of DOE Representatives 

Brent Blunt Larry Romanowski 

Joel Cantrell Kent Rosenberger 

Alex Cozzi Paul Rowan 

Pete Fledderman David Sherburne 

Jim Heffner Malcolm Smith 

Keith Liner Dan Wells 

Larry Ling Dante Wells 

David Martin 

Phillip Norris 

Don Padgett 

 

4.0 REFERENCES 

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

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

DOE. ESH-WPG-2006-00132, “Letter to John McCain (DHEC), Z-Area Industrial Solid Waste 

Landfill Vault Cracking (U).” Aiken, SC. DOE. 2006a. 

NRC. AU.S. Nuclear Regulatory Commission Technical Evaluation Report for the U.S. 

Department of Energy Savannah River Site Draft Section 3116 Waste Determination for Salt 

Waste Disposal.@ Washington, DC: NRC. 2005. 
14 

NRC. “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, D.C.: NRC. 2007. 

Culbertson, B.H., “Waste Acceptance Criteria for Aqueous Waste Sent to the Z-Area Saltstone 

Production Facility.” X-SD-Z-00001, Revision 2, February 2007. 

Ketusky, E. T., “Sampling Strategy for Tank 50 Point of Compliance Transfers to Saltstone”, 

CBU-PIT-2005-00014, Revision 0, Westinghouse Savannah River Company, Aiken, South 

Carolina, 2005. 

Westinghouse Savannah River Company (WSRC), 2005. Memorandum from P. J. Rowan to 

B.C. Blunt, “NESHAP Evaluation: Saltstone Processing Facility, 0.2 Curies/Gallon Low Curie 

Salt (LCS) Feed Mixer at Vault Road Concept (MAVRC), Revision 1.” August 16, 2005. 

Westinghouse Savannah River Company (WSRC), 2006a. Manual 3Q5, Procedure 19, 

“Sample Packaging for Off Site Shipments of Environmental Samples,” Revision 1. November 

15, 2006. 

Westinghouse Savannah River Company (WSRC), 2006b. Letter from D.G. Wells, P.G., to 

Roger E. Schweitzer, South Carolina Department of Health and Environmental Control, 

“Groundwater Monitoring Plan for the Z area Saltstone Disposal Facility, Revision 4.” 

September 25, 2006. 

Westinghouse Savannah River Company (WSRC), 2007a. Manual 3Q5, Procedure 7, 

“Specifications for Installation of Piezometers and Monitoring Wells,” Revision 5. June 4, 2007. 

Westinghouse Savannah River Company (WSRC), 2007b. Manual 3Q5, Procedure 15, 

“Sampling Groundwater Monitoring Wells,” Revision 11. May 1, 2007.