April 10, 2013 

MEMORANDUM TO: Gregory Suber, Chief 

Low Level Waste Branch 

Environmental Protection 

 and Performance Assessment Directorate 

Division of Waste Management 

 and Environmental Protection 

THRU: Chris McKenney, Chief /RA/ 

Performance Assessment Branch 

Environmental Protection 

 and Performance Assessment Directorate 

Division of Waste Management 

 and Environmental Protection 

FROM: Cynthia S. Barr, Sr. Systems Performance Analyst /RA/ 

Performance Assessment Branch 

Environmental Protection 

 and Performance Assessment Directorate 

Division of Waste Management 

 and Environmental Protection 

SUBJECT: TECHNICAL REVIEW OF “TANK 18 AND 19 SPECIAL ANALYSIS 

FOR THE PERFORMANCE ASSESSMENT FOR THE F-TANK FARM 

AT THE SAVANNAH RIVER SITE”, SRR-CWDA-2010-00124, REV. 0, 

FEBRUARY 2012 (DOCKET NO. PROJ0734) 

The U.S. Nuclear Regulatory Commission (NRC) staff has performed a technical review of the 

subject document prepared by the United States Department of Energy (DOE) to support Tanks 

18 and 19 closure at the F-Area Tank Farm Facility (FTF) at Savannah River Site. This 

technical review memorandum supports Monitoring Factor 1.1, “Final Inventory and Risk 

Estimates” listed in NRC staff’s monitoring plan for FTF (NRC, 2013). The NRC staff concludes 

that while the special analysis provides useful information regarding the sensitivity of predicted 

FTF peak doses to key modeling parameters such as Tank 18 final inventory, Pu solubility, and 

natural system Kd, due to its limited nature, additional information is needed to address 

remaining technical issues not addressed by DOE analyses to support the compliance 

demonstration for Tank 18 and the larger FTF facility. 

Enclosure: 

Technical Review of Tank 18 

 and 19 Special Analysis 

CONTACT: C. Barr, FSME/DWMEP 

(301) 415-4015 
MEMORANDUM TO: Gregory Suber, Chief 

Low Level Waste Branch 

Environmental Protection 

 and Performance Assessment Directorate 

Division of Waste Management 

 and Environmental Protection 

THRU: Chris McKenney, Chief

Performance Assessment Branch 

Environmental Protection 

 and Performance Assessment Directorate 

Division of Waste Management 

 and Environmental Protection 

FROM: Cynthia S. Barr, Sr. Systems Performance Analyst

Performance Assessment Branch 

Environmental Protection 

 and Performance Assessment Directorate 

Division of Waste Management 

 and Environmental Protection 

SUBJECT: TECHNICAL REVIEW OF “TANK 18 AND 19 SPECIAL ANALYSIS 

FOR THE PERFORMANCE ASSESSMENT FOR THE F-TANK FARM 

AT THE SAVANNAH RIVER SITE”, SRR-CWDA-2010-00124, REV. 0, 

FEBRUARY 2012 (DOCKET NO. PROJ0734) 

The U.S. Nuclear Regulatory Commission (NRC) staff has performed a technical review of the 

subject document prepared by the United States Department of Energy (DOE) to support Tanks 

18 and 19 closure at the F-Area Tank Farm Facility (FTF) at Savannah River Site. This 

technical review memorandum supports Monitoring Factor 1.1, “Final Inventory and Risk 

Estimates” listed in NRC staff’s monitoring plan for FTF (NRC, 2013). The NRC staff concludes 

that while the special analysis provides useful information regarding the sensitivity of predicted 

FTF peak doses to key modeling parameters such as Tank 18 final inventory, Pu solubility, and 

natural system Kd, due to its limited nature, additional information is needed to address 

remaining technical issues not addressed by DOE analyses to support the compliance 

demonstration for Tank 18 and the larger FTF facility. 

Enclosure: 

Technical Review of Tank 18 

 and 19 Special Analysis 

CONTACT: C. Barr, FSME/DWMEP 

(301) 415-4015 

DISTRIBUTION: AMohseni CMcKenney JShaffner CGrossman 

LParks GAlexander MFuhrmann 

ML13100A230 

OFC DWMEP:TR DWMEP:LA DWMEP:PM DWMEP:BC DWMEP:TR 

NAME CBarr TMoon HFelsher CMcKenney CBarr 

DATE 04/09/13 04/09/13 04/09/13 04/10/13 04/10/13 

OFFICIAL RECORD COPY
Enclosure 

Technical Review of Tank 18 and 19 Special Analysis 

Date: April 9, 2013 

Reviewer: Cynthia S Barr 

Documents: Tank 18 and 19 Special Analysis for the Performance Assessment for the FTank Farm at the Savannah River Site, SRR-CWDA-2010-00124, Rev. 0, 

February 2012 

Summary:

The Tanks 18 and 19 special analysis is used by the U.S. Department of Energy (DOE) to 

evaluate new information obtained since preparation of the F Tank Farm (FTF) performance 

assessment (PA) (DOE, 2009). The new information evaluated includes: (i) final inventories 

for Tanks 18 and 19; and (ii) additional key radioelement sensitivity analyses (Pu solubility and 

Kd). This sensitivity analysis was performed because earlier analyses showed that considering 

the final inventory for Tank 18 in the reference case FTF PA model, the peak dose from Tank 

18 could be significant at around 5 mSv/yr (500 mrem/yr) over longer simulation timeframes. 

However, DOE concludes that the additional sensitivity analysis demonstrate that the FTF base 

case model incorporates conservative approaches/inputs and the peak doses associated with 

Pu-239 would likely occur even later in time. 

NRC Evaluation:

In general, the Tanks 18 and 19 special analysis provides useful information about the 

sensitivity of dose predictions to key modeling parameters including Pu solubility and natural 

system Kd. Updated geochemical modeling results (Denham, 2012) are propagated through 

FTF risk models to provide improved risk estimates for Tank 18. DOE also attempted to 

address the impact of cement leachate on near-field sorption as recommended in previous 

NRC comment. The results of the special analysis show that the doses could be above or 

below the dose standards in 10 CFR Part 61, Subpart C considering longer periods of 

performance. Therefore, the timing of peak dose may still be important to the compliance 

demonstration. 

In its TER (NRC, 2011), NRC staff stated the following concern related to timing of peak dose: 

However, considering the fact that unacceptably high peak doses could occur 

within the 10,000 year period of compliance with only a factor of 3 to 4 faster time 

to collective failure of a combination of barriers for Tc or Pu, respectively, and 

considering the large uncertainty associated with predictions of long-term 

performance of engineered barriers, NRC staff are not convinced that the high 

peak doses currently presented in DOE’s PA (or lower peak doses of unknown 

magnitude that might be associated with a more realistic model) could not be 

realized within a 10,000 year compliance period. (NRC, 2011)
2 

NRC staff thinks DOE has made significant improvements to its initial FTF PA solubility 

modeling using the latest thermodynamic data available in the literature as discussed in more 

detail in a separate technical review memorandum to be issued later this year. However, as 

discussed above, the Tank 18 and 19 special analysis shows that the doses associated with 

Tank 18 could be above or below the 10 CFR 61.41 performance objective considering longer 

periods of performance. Additionally, DOE’s updated solubility modeling also shows that the 

solubility of Pu-239 is sensitive to redox conditions. At higher Eh (above around +0.45 V), the 

updated solubility modeling shows the Pu solubility could be significantly higher than assumed 

in DOE’s PA for oxidized (Region II) conditions (i.e., around 5E-08 mol/L compared to 3E-13 

mol/L). 

Figure 1 shows that the chemical barrier afforded by the tank grout or contaminated zone 

(shown in purple) is the single-most important barrier affecting the timing of peak Pu-239 dose 

in DOE’s reference case. The green, vertical line in Figure 1 shows the first chemical transition 

modeled in DOE’s PA that delineates the transition from reduced to oxidized conditions. As 

discussed above, if the Eh of the system is above around +0.45 V in the oxidized (Region II) 

chemical state, DOE’s updated solubility modeling shows that the release of Pu-239 from Tank 

18 could be risk-significant much earlier in time at around 10,000 years. Thus, the updated 

solubility modeling shows that a factor of approximately 3 earlier time-to-failure of the most 

important barrier to timing of peak dose, the tank grout/contaminated zone chemical barrier, 

could occur making a peak dose within 10,000 years much more plausible. 

Another source of uncertainty in the timing of peak dose related to chemical transition times 

was addressed by DOE in a Request for Additional Information (RAI) response but was not 

considered in the Tanks 18 and 19 special analysis. In FTF RAI response (DOE, 2011), DOE 

performed a “Case G” analysis to study a potential conceptual model referred to as Condition 2 

in DOE’s PA (SRS-REG-2007-00002, Rev. 1). In Condition 2, a fast flow path exists through 

the tank grout prior to significant (bulk) grout degradation. Therefore, flow through the system 

is dominated by fractures or cracks that might form in the system over time (e.g., shrinkage 

gaps, or cracks that might develop due to thermal or mechanical stresses imposed on the 

system during curing, or due to corrosion of steel components) and waste release is dominated 

by water that, after a short period of time, is not assumed to be chemically conditioned via 

prolonged interactions with the reducing grout. Because the Case G scenario defeats the 

primary barrier prolonging the peak dose in DOE’s FTF PA (i.e., the purple, chemical barrier 

shown in Figure 1), the peak dose occurs within the 10,000 year performance period1

 at doses 

 

1 The “NRC Staff Guidance for Activities Related to U.S. Department of Energy Waste Determinations, 

Draft Final Report for Interim Use” (NUREG-1854) recommends “Generally, a period of 10,000 years 

after closure is sufficient to capture the peak dose from the more mobile, long-lived radionuclides and to 

demonstrate the influence of the natural and engineered systems in achieving the performance 

objectives (NRC, 2000). However, assessments beyond 10,000 years may be necessary to ensure (1) 

that the disposal of certain types of waste does not result in markedly high impacts to future generations 

or (2) evaluate waste disposal at arid sites with extremely long groundwater travel times. Periods of 

performance shorter than 10,000 years are generally not appropriate for disposal facilities for incidental 

waste, because of the larger fraction of long-lived radionuclides compared to a typical commercial lowlevel waste (LLW) disposal facility. Presenting and understanding long-term risk (e.g., greater than 

10,000 years) can be an important part of performance assessment analyses, even if those risks are not 

used to demonstrate compliance with the performance objectives of 10 CFR Part 61, Subpart C.” 
3 

above the 0.25 mSv/yr (25 mrem/yr) dose standard used to evaluate compliance with 10 CFR 

61.41. 

While DOE characterized Case G as highly unlikely or incredible, the Pu solubility peer review 

group that evaluated DOE’s Pu waste release modeling (Cantrell et al., 2011) stated the 

following: 

Slow carbonation of the grout as a result of diffusion of carbon dioxide into the 

grout with water seems like a low probability scenario. Fracturing of the grout with 

preferential flow through the cracks would appear to be a much more likely 

scenario and should therefore be evaluated. 

The peer review group suggests that a key modeling assumption in DOE’s FTF reference 

case—diffusion limited transport of dissolved carbon dioxide through tank grout—seems less 

likely. The peer review group expectation that fluid flow will occur through cracks in the tank 

grout might also be extended to the steel liner corrosion modeling, as well as the cementitious 

material degradation modeling. Case G considers the potential impact of flow through cracks 

implicitly with earlier steel liner failure and chemical transition times—modeling assumptions 

that lead to doses above the dose limit of 0.25 mSv/yr (25 mrem/yr) within the 10,000 year 

performance period. DOE, however, did not address the important peer review group 

comment regarding flow through cracks in the Tanks 18 and 19 special analysis that might 

hasten the time to steel liner and chemical barrier failure times (green and purple barriers in 

Figure 1, respectively). A better understanding of the likelihood and performance impact of a 

scenario similar to Case G is, therefore, considered by NRC staff to be important to DOE’s 

compliance demonstration. Many of the key monitoring factors developed by NRC staff in its 

FTF monitoring plan (NRC, 2013) provide additional information to evaluate the likelihood and 

performance impact of preferential flow through the grouted tanks. 

 

For FTF, NRC staff is also concerned with an alternative scenario in which the water table 

periodically rises above the bottom of the tanks (or the tank bottoms are within the zone of 

water table fluctuation), potentially leading to accelerated corrosion and direct contact of 

saturated groundwater with the contaminated zone. Because Type IV tanks like Tank 18: (i) 

have bottoms located at or near the elevation of the long-term average water table; (ii) have no 

vault annulus to grout; (iii) have experienced groundwater in-leakage into tank vaults; and (iv) 

contain a risk-significant inventory of key radionuclides such as Pu-239 and Np-237, the 

likelihood of early, unconditioned release of tank waste due to water table rise is of particular 

concern for Type IV tanks. Thus, in its TER for FTF (NRC, 2011), NRC staff recommended 

DOE perform experiments to evaluate radionuclide solubility under a range of chemical 

conditions relevant to the residual sludge in the grouted waste tanks. If DOE can show 

dissolved concentrations of key radionuclides can be limited to non-risk-significant levels under 

all relevant chemical conditions, the conceptual model for waste release (and the timing of the 

release) becomes less important. Experiments to study solubility are the focus of Monitoring 

Factor 2.1 in NRC’s monitoring plan (NRC, 2013). 

Additionally, DOE’s Tanks 18 and 19 special analysis does not address a key comment made 

in NRC staff’s FTF TER (NRC, 2011) related to Pu sorption in the environment—that travel 

times for more mobile and less mobile forms of Pu are averaged together leading to longer 

travel times for the smaller fraction of more mobile Pu. If DOE represents the more mobile 

form of Pu explicitly in its PA model, rather than averaging the properties of both immobile and 
4 

mobile forms together, then travel times of Pu in the natural system to a point of assessment 

may be relatively rapid for the more mobile fraction of Pu compared to the Pu travel times 

reflected in the base case and sensitivity studies. It is also important to note that because 

Tank 18 is close to the FTF boundary and has virtually no vadose zone, travel times from Tank 

18 to the 1 m point of compliance are expected to be much shorter than to the 100 m point of 

compliance making compliance with the 10 CFR 61.42 performance objective potentially 

bounding if DOE must rely on travel time to the 100 m point of assessment to demonstrate 

compliance with 10 CFR 61.41. 

In lieu of addressing the issue related to Kd averaging, DOE retained a single composite Kd for 

Pu and revised natural system Pu Kds only upwards (Kds of 650 to 1300 L/kg are used in 

sensitivity cases versus a Kd of 270 L/kg used in DOE’s FTF reference case for Pu in sand). 

This modeling change serves to increase travel times to the point of compliance, partially 

offsetting the significantly earlier waste release times that result from updated solubility 

modeling cases. 

In select sensitivity cases, DOE initially assigns a value of 1300 L/kg for the Pu sand Kd to 

reflect the impact grout leachate on sorption of Pu. In other sensitivity cases, DOE assigns a 

value of 650 L/kg for Pu sand Kd for all time. The new Kds are based on a statistical analysis of 

available sorption data for the site (Almond, et al., 2012). Both of these Kd values are 

significantly higher than the value of 270 L/kg DOE used in the FTF PA. The NRC staff 

discusses technical concerns related to the updated Pu Kd analysis in a separate technical 

review memorandum to be issued later this year. For the reasons mentioned above, NRC staff 

does not think that the range of parameter values evaluated by DOE in its sensitivity analysis 

encompass the full range of measured values, nor does the modeling approach address the 

complexities of Pu transport reflected in site-specific studies. 

In summary, DOE’s updated solubility modeling has not ruled out risk-significant release of Pu239 under oxidizing conditions. At reasonable, although what is characterized by DOE as 

“conservative” Eh, Pu-239 can be released at risk-significant quantities leading to doses that 

are comparable to the reference case dose for Tank 18, around 3 mSv/yr (300 mrem/yr). 

Experimental verification of the extent to which groundwater is chemically conditioned by the 

tank grout over time (e.g., the evolution of Eh over time) and the expected change in solubility 

of key radionuclides in response to these chemical changes is also important. If releases are 

expected to be risk-significant, it will also be important for DOE to rigorously evaluate the timing 

of the releases to demonstrate compliance within the performance period. As illustrated in 

Figure 1, factors that are important to the timing of peak dose in DOE’s reference case in order 

of importance are the following: 

• Chemical barriers, 

• Natural system (Kds), 

• Steel liner, and 

• Basemat. 

DOE’s updated solubility modeling shows that the chemical barrier for Pu-239 may be much 

less effective at around 10,000 years or upon transition to oxidized conditions delineated by the 

vertical, green line in Figure 1 (versus 30,000 years delineated by the vertical red line in Figure 
5 

1). DOE did not evaluate alternative conceptual models (e.g., flow through cracks in the tank 

grout) in its special analysis that may also lead to earlier chemical transitions times (a shift in 

the vertical green line to earlier times). Therefore, it will be important for DOE to provide 

additional support for its reference case PA model or to rule out alternative configurations that 

may lead to unacceptable results. 

DOE did evaluate natural system Kds in the Tanks 18 and 19 special analysis as 

recommended in NRC staff’s FTF TER; however, DOE only revised its natural system Kds 

upwards, which serves to further delay the timing of peak dose. DOE did not evaluate the 

significance of site-specific data on more mobile forms of Pu that if explicitly represented in the 

FTF PA model may lead to significant doses within the period of performance. For example, if 

a significant fraction of more mobile Pu-239 is present in the subsurface at FTF, using a Kd of 

16 L/kg (SRS-REG-2007-00002, Rev. 1), bulk soil density of 1.65 g/cm3

, and a porosity of 0.38, 

the retardation factor for more mobile forms of Pu-239 can be calculated at a value of 70 using 

the following equation: 

ߩ ൅ 1 ൌ௙ ܴ

ߟ

ௗܭ כ

 70 ൌ 1 ൅ ଵ.଺ହ

଴.ଷ଼

16 כ

If groundwater travel times to the 1 and 100 m wells are on the order of around 10 years, travel 

times to the points of assessment (1 and 100 m exposure points) could be on the order of 

hundreds, rather than tens of thousands of years currently assumed in DOE’s reference case 

and updated Tanks 18 and 19 special analysis. Therefore, it will be important for DOE to 

demonstrate that (i) more mobile forms of Pu released from the tanks are not present in risksignificant quantities, or (ii) that geochemical conditions are favorable in the sense that Pu is 

immobilized and Pu concentrations are reduced to non-risk-significant levels along FTF release 

paths from the FTF tanks in the natural environment. Evaluation of key radionuclide mobility in 

the subsurface is listed under MF 4.1 in NRC’s FTF monitoring plan (NRC, 2013). 

Finally, DOE does not address technical issues raised by NRC associated with steel liner 

corrosion and basemat sorption in its special analysis. The NRC staff developed monitoring 

factors 3.1 and 3.5 in its FTF monitoring plan to address these issues (NRC, 2013). It is 

important to note that the Tank 18 basemat is also an important barrier mitigating Np release 

and is also listed in NRC staff’s FTF monitoring plan (NRC, 2013) under monitoring factor 3.5. 
6 

Figure 1 Barriers to Timing of Peak Dose for Type IV Tanks in DOE’s Reference Case 
7 

NRC staff also has concerns with comments made by DOE in the Tanks 18 and 19 special 

analysis: 

It should be noted that irrespective of the plutonium solubility value, the peak doses 

associated with Pu-239 are always below the 25 mrem/yr performance objective 

within the 10,000-year performance period. This sensitivity study also shows that 

the multiple barriers to Pu-239 release are effective and can prevent a significant 

release in the 10,000-year time period regardless of the Pu-239 solubility limits. 

These additional sensitivity analyses demonstrate that the FTF Base Case model 

incorporates conservative approaches/inputs and the peak doses associated with Pu239 would likely occur even farther beyond the 10,000 year performance period if these 

conservative approaches/inputs were eliminated. 

NRC staff does not agree with the statement that sensitivity analyses show that barriers are 

effective and can prevent a significant release in 10,000 years. First, sensitivity analyses do 

not show whether a barrier is or is not effective; sensitivity analyses show the impact of a 

model or model parameter change on a model output. Actual barrier effectiveness is 

dependent on the field emplaced properties of the barrier(s) and the internal and external 

forces acting on the barrier(s) that may or may not be represented in a sensitivity study. The 

NRC staff note that the sensitivity analysis conducted to support the special analysis for Tanks 

18 and 19 does not appear to encompass the full range of potential performance of FTF 

barriers as discussed above. Second, the assumed level of performance of key barriers in 

DOE’s reference case PA is not fully supported. Key barriers to facility performance should be 

supported with multiple lines of evidence and should consider, as appropriate, various features, 

events, and processes that might significantly affect the effectiveness of the barrier. While 

DOE performed updated solubility modeling (Denham, 2012) that generally improves risk 

estimates for the site, DOE has not performed experimental validation of its modeling results. 

Furthermore, DOE’s updated solubility modeling shows that the Pu dose can be above the Part 

61, Subpart C performance objectives but does not consider important factors that might serve 

to hasten the time of peak (or risk-significant) dose within the performance period. 

NRC staff also has concerns with the statement about the conservatism of the base case 

model for the following reasons: (i) the range of parameter values used in the sensitivity 

analysis may not reflect the full range of parameter values in site-specific analyses; and (ii) 

because the sensitivity analyses only evaluate a limited set of potential outcomes, the 

calculations are inadequate to show whether the base case is or is not conservative. 

Furthermore, NRC staff also finds statements regarding the timing of peak dose misleading as 

the updated solubility modeling actually shows that the peak doses could occur much earlier in 

time. As indicated above, DOE conducted updated modeling to address deficiencies identified 

by the Pu solubility peer review group with respect to the geochemical modeling in the FTF PA 

(Denham, 2012) and found that under oxidizing conditions, Pu could be released at risksignificant levels 20,000 years earlier in time than assumed in the basecase model. 

The combined impact of all potential conservatisms and non-conservatisms in DOE’s reference 

PA model is not clear. Based on consideration of all existing information, NRC staff concludes 

that the performance objectives in 10 CFR 61.41 and 61.42 may or may not be met considering 

a 10,000 year period of performance. Therefore, NRC staff continues to recommend waste 
8 

release experiments to increase support for key modeling assumptions related to Pu solubility. 

Additional information related to other key barriers may also be needed pending the results of 

the solubility experiments.

Teleconference or Meeting:

During the September 26 to 27th onsite observation at FTF, NRC staff sought clarification from 

DOE on a number of statements made in the Tank 18 and 19 special analysis. DOE clarified 

that expert panel statements regarding (i) the potential for degraded liner corrosion product 

sorption and (ii) the expected late timing of the Pu peak dose were actually made in verbal 

discussions between DOE and the expert panel and were not documented in the Pu solubility 

peer review report. NRC also discussed the impact of DOE’s FTF PA assumption that the tank 

grout is completely degraded at 500 years in Configurations B through F. Although this might 

appear to be a conservative assumption, because DOE assumes that infiltrating groundwater 

flows through the grout monolith (versus through cracks in the grout monolith), a greater mass 

of tank grout is available to condition infiltrating groundwater to low Eh and high pH thereby 

maintaining low solubilty of several key radionuclides in the waste zone for longer periods of 

time. If flow were primarily through cracks, then the buffering capacity of the grout along crack 

faces would become depleted in a shorter period of time and chemical transitions to higher 

solubility could occur significantly earlier in time. Therefore, NRC staff plan to monitor the 

extent of groundwater conditioning and chemical transition times in monitoring factors 2.2 and 

3.2 of NRC staff’s monitoring plan (NRC, 2013). 

Follow-up Actions:

There are no follow-up actions. 

Open Issues:

There are currently no open issues. The FTF monitoring plan (NRC, 2013) addresses 

remaining technical issues related to solubility control of Pu (monitoring factor 2.1), 

groundwater conditioning (monitoring factors 2.2 and 3.2), steel liner corrosion (monitoring 

factor 3.1), basemat sorption (monitoring factor 3.5), and natural system Kd (monitoring factor 

4.1). 

Conclusions:

The combined impact of all potential conservatisms and non-conservatisms in DOE’s reference 

PA model is not clear; additional information is needed to support the compliance 

demonstration for Tank 18 and the larger FTF. Therefore, contrary to DOE’s conclusion in the 

Tank 18 and 19 special analysis, NRC staff continues to recommend waste release 

experiments to better understand Pu solubility under a range of chemical conditions. 

NRC staff concludes that while the Tanks 18 and 19 special analysis provides useful 

information regarding the sensitivity of predicted FTF peak doses to key modeling parameters 

such as Tank 18 final inventory, Pu solubility, and natural system Kd, due to its limited nature, 

additional information is needed to address remaining issues identified in NRC staff’s technical 

evaluation report (NRC, 2011) that were not evaluated in the DOE analysis to support the 
9 

compliance demonstration for Tank 18 and the larger FTF facility. NRC staff’s plan for 

monitoring factors important to FTF performance is provided in NRC’s FTF monitoring plan 

(NRC, 2013). 

References:

Cantrell et al., Plutonium Solubility Peer Review Report. LA-UR-2012-00079. Prepared for 

DOE Savannah River Operations Office (DOE-SR), Los Alamos National Laboratory, New 

Mexico, December 2011. 

Denham, M. Evolution of Chemical Conditions and Estimated Plutonium Solubility in the 

Residual Waste Layer During Post-Closure Aging of Tank 18. SRNL-STI-2012-00087. 

Savannah River National Laboratory, Savannah River Nuclear Solutions, LLC, Aiken, SC 

29808, February, 2012. 

NRC. U.S. Nuclear Regulatory Commission Staff Requests for Additional Information on the 

"Draft Basis for Section 3116 Determination for Closure of F-Tank Farm at the Savannah River 

Site,": DOE/SRS-WD-2010-001, Rev. 0, and on "Performance Assessment for the F-Tank 

Farm for the Savannah River Site," SRS-REG-2008-00002, Rev. 1,U.S. Nuclear Regulatory 

Commission, Washington DC. ADAMS Accession Number: ML103190402. December 3, 2010. 

NRC. NRC Technical Evaluation Report for F-Area Tank Farm Facility, Savannah River Site, 

South Carolina, ADAMS Accession Number: ML112371715. US Nuclear Regulatory 

Commission, October 27, 2011. 

NRC. U.S. Nuclear Regulatory Commission Plan for Monitoring Disposal Actions Taken by the 

U.S. Department of Energy at the Savannah River Site F-Area Tank Farm Facility in 

Accordance with the National Defense Authorization Act for Fiscal Year 2005. ADAMS 

Accession Number ML12212a192. US NRC, January 2013. 

SRS-REG-2007-00002 Rev 1. Performance Assessment for the F-Tank Farm at the Savannah 

River Site. Savannah River Site, Aiken, SC, March, 31, 2010. 

SRR-CWDA-2010-00124, Rev. 0, Tank 18 and 19 Special Analysis for the Performance 

Assessment for the F-Tank Farm at the Savannah River Site, SRR-CWDA-2010-00124, Rev. 

0, February 2012.

SRR-CWDA-2012-00019, Tank 18 Plutonium Enhanced Probabilistic Analysis - GoldSim FTF 

Version 2.6, Savannah River Site, Aiken, SC, February 2012. 

SRNL-L4221-2012-00001, Jordan, J., PORFLOW Sensitivity Studies Report, Savannah River 

Site, Aiken, SC, February 2012. 

SRR-SWDA-2011-00054, Comment Response Matrix for United States Nuclear Regulatory 

Commission Staff Comments on the Draft Basis for Section 3116 Determination and 

Associated Performance Assessment for the F-Tank Farm at the Savannah River Site, Rev. 1, 

Savannah River Site, Aiken, SC, 2011