October 30, 2013 

MEMORANDUM TO: Gregory Suber, Chief 

Low-Level Waste Branch 

Environmental Protection 

 and Performance Assessment Directorate 

Division of Waste Management 

 and Environmental Protection 

THRU: Christepher McKenney, Chief /RA/ 

Performance Assessment Branch 

Environmental Protection 

 and Performance Assessment Directorate 

Division of Waste Management 

 and Environmental Protection 

FROM: Christopher Grossman, Systems Performance Analyst /RA/

Performance Assessment Branch 

Environmental Protection 

 and Performance Assessment Directorate 

Division of Waste Management 

 and Environmental Protection 

SUBJECT: TECHNICAL REVIEW: U.S. DEPARTMENT OF ENERGY 

DOCUMENTATION RELATED TO TANKS 18F AND 19F FINAL 

CONFIGURATIONS WITH AN EMPHASIS ON GROUTING FROM 

RECOMMENDATIONS AND TESTING TO FINAL SPECIFICATIONS 

AND PROCEDURES (PROJECT NO. PROJ0734) 

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

several documents prepared by the U.S. Department of Energy (DOE) that provide information 

on closure of Tanks 18F and 19F with an emphasis on grout formulations, testing, placement 

procedures and final configurations. This technical review activity supports Monitoring Factors 

3.3, “Shrinkage and Cracking”, and 3.4, “Grout Performance”, in NRC staff’s F-Tank Farm (FTF) 

Monitoring Plan, Rev. 0 (Available in the Agencywide Documents Access and Management 

System (ADAMS) Accession No. ML12212A192). The NRC staff concludes that performance 

requirements for grout formulations recommended and tested for Tanks 18F and 19F closure 

are generally consistent with bulk, initial chemical and hydraulic properties assumed in DOE’s 

FTF Performance Assessment (SRS-REG-2007-00002, Rev. 1). However, the NRC staff also 

concludes that DOE has not provided sufficient information and testing to exclude preferential 

flow through the tank grout monolith from its reference case. Primarily, the NRC staff expects 

CONTACT: Christopher Grossman, FSME/DWMEP 

 (301) 415-7658 
G. Suber - 2 - 

DOE to provide additional information related to the extent and performance impact of shrinkage 

to have reasonable assurance that the performance objectives specified in Subpart C of Part 61 

of Title 10 of the Code of Federal Regulations (10 CFR Part 61, Subpart C) will be met. Further, 

during the review of tank grouting video, NRC staff has observed potential segregation of tank 

grout that could enhance the extent of shrinkage along the periphery of the Type IV tanks (i.e., 

along the tank walls). NRC staff also expects DOE to provide additional information on the 

potential for thermal cracking of the grout monolith for Tanks 18F and 19F. The NRC staff will 

continue to evaluate the potential for shrinkage and cracking induced preferential flow through 

the tank grout under Monitoring Factor 3.3, “Shrinkage and Cracking” (See ML12212A192). 

NRC also continues to monitor the potential for segregation of emplaced grout and its impacts 

on flow through the grout monolith and waste release under Monitoring Factor 3.4, “Grout 

Performance”. NRC staff believes this information is needed for NRC to have reasonable 

assurance that the FTF will meet 10 CFR Part 61, Subpart C. 

The NRC staff will also continue to monitor void volumes in the emplaced grout to the extent 

information is available (Monitoring Factor 3.4, “Grout Performance”), the importance of alkalisilica reactivity on cementitious material degradation (Monitoring Factor 3.3, “Shrinkage and 

Cracking”) and the impact of limestone additions to the grout mix on pH buffering of water 

contacting the emplaced grout (Monitoring Factor 3.4, “Grout Performance”). The NRC staff 

believes this information would enhance DOE’s demonstration that the performance objectives 

of 10 CFR Part 61, Subpart C are met with reasonable assurance. 

Enclosure: 

Technical Review of Documents Related 

 to Tank 18F and 19F Grout Formulations, 

 Operations, and Final Closure at the 

 F-Area Tank Farm at the Savannah River Site 
G. Suber - 2 - 

DOE to provide additional information related to the extent and performance impact of shrinkage 

to have reasonable assurance that the performance objectives specified in Subpart C of Part 61 

of Title 10 of the Code of Federal Regulations (10 CFR Part 61, Subpart C) will be met. Further, 

during the review of tank grouting video, NRC staff has observed potential segregation of tank 

grout that could enhance the extent of shrinkage along the periphery of the Type IV tanks (i.e., 

along the tank walls). NRC staff also expects DOE to provide additional information on the 

potential for thermal cracking of the grout monolith for Tanks 18F and 19F. The NRC staff will 

continue to evaluate the potential for shrinkage and cracking induced preferential flow through 

the tank grout under Monitoring Factor 3.3, “Shrinkage and Cracking” (See ML12212A192). 

NRC also continues to monitor the potential for segregation of emplaced grout and its impacts 

on flow through the grout monolith and waste release under Monitoring Factor 3.4, “Grout 

Performance”. NRC staff believes this information is needed for NRC to have reasonable 

assurance that the closure of FTF tanks will meet 10 CFR Part 61, Subpart C. 

The NRC staff will also continue to monitor void volumes in the emplaced grout to the extent 

information is available (Monitoring Factor 3.4, “Grout Performance”), the importance of alkalisilica reactivity on cementitious material degradation (Monitoring Factor 3.3, “Shrinkage and 

Cracking”) and the impact of limestone additions to the grout mix on pH buffering of water 

contacting the emplaced grout (Monitoring Factor 3.4, “Grout Performance”). The NRC staff 

believes this information would enhance DOE’s demonstration that the performance objectives 

of 10 CFR Part 61, Subpart C are met with reasonable assurance. 

Enclosure: 

Technical Review of Documents Related 

 to Tank 18F and 19F Grout Formulations, 

 Operations, and Final Closure at the 

 F-Area Tank Farm at the Savannah River Site 

DISTRIBUTION (w/Enclosure): CBarr GAlexander LParks MFuhrmann 

DPickett, CNWRA WIR Service List DOE SRS Email List 

ML13269A365 

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

NAME CGrossman TMoon HFelsher CMKenney CGrossman 

DATE 09/30/13 10/1/13 10/3/13 10/30/13 10/30/13 

OFFICIAL RECORD COPY
Enclosure 

Technical Review of Documents Related to Tank 18F and 19F 

Grout Formulations, Operations, and Final Closure at the 

F-Area Tank Farm at the Savannah River Site 

Date: September 30, 2013 

Reviewers: 

Roberto Pabalan, Center for Nuclear Waste Regulatory Analyses 

Cynthia Dinwiddie, Southwest Research Institute®

Gary Walter, Southwest Research Institute®

Christopher Grossman, U.S. Nuclear Regulatory Commission (NRC) 

Documents: 

Alexander, O. “Placement of Grout Tank 18 Center Riser.” Work Order No. 01087939–16, 

Revision 03. March 29, 2012. 

C-DCF-F-01524. Ganguly, A. “Revise Tanks 18F & 19F Closure Grout Specification.” Aiken, 

South Carolina: Savannah River Remediation, LLC. February, 28, 2012. 

C-DCF-F-01527, Forty, R.W. “Revise Tanks 18F & 19F Closure Grout Specification for Testing 

Samples.” Aiken, South Carolina: Savannah River Remediation, LLC. March 29, 2012. 

C-SPP-F-00055, Forty, R.W. “Furnishing and Delivery of Tank Closure Grout.” Revision 2. 

Aiken, South Carolina: Savannah River Remediation, LLC. August 25, 2011. 

C-TRT-F-00005, Ganguly, A. “Technical Summary Report for Tanks 18F and 19F Closure — 

Initial Trial Batching (U).” Revision 0. Aiken, South Carolina: Savannah River Remediation, 

LLC. April 17, 2012. 

Isherwood, A. “Placement of Grout Tank 18 Various Equipment Locations.” Work Order No. 

01087939–17, Revision 1. March 1, 2012. 

Patton, G. “Placement of Grout Tank 19 Various Equipment Locations.” Work Order No. 

01087938–16, Revision 1. March 1, 2012. 

Patton, G. “Placement of Grout Tank 19 Center Riser.” Work Order No. 01087938–15, Revision 

04. April 23, 2012. 

SRNL-L3100-2011-00180, Langton, C. A. and D.B. Stefanko. “Bulk Fill Grout 

Recommendations for Tanks 18-F and 19-F.” Memorandum to F.M. Pennebaker and R.C. Jolly 

Jr. Aiken, SC: Savannah River National Laboratory. August 31, 2011. 

SRNL-RP-2011-00977, Stefanko, D.B. and C.A. Langton. “Tanks 18-F and 19-F Grout Fill 

Engineering and Performance Requirements.” Revision 0. Aiken, South Carolina: Savannah 

River National Laboratory. August, 2011. 
- 2 - 

SRNL-STI-2011-00551, Stefanko, D.B. and C.A. Langton. “Tanks 18 and 19-F Structural 

Flowable Grout Fill Material Evaluation and Recommendations.” Revision 0. Aiken, South 

Carolina: Savannah River National Laboratory. September, 2011. 

SRNL-STI-2011-00564, Stefanko, D.B. and C.A. Langton. “Tank 18 and 19-F Tier 1A 

Equipment Fill Mock Up Test Summary.” Revision 0. Aiken, South Carolina: Savannah River 

National Laboratory. September, 2011. 

SRNL-STI-2011-00592, Stefanko, D.B. and C.A. Langton. “Tanks 18 and 19-F Equipment Grout 

Fill Material Evaluation and Recommendations.” Revision 0. Aiken, South Carolina: Savannah 

River National Laboratory. November 2011. 

SRNL-STI-2011-00749, Stefanko, D.B. and C.A. Langton. “Tank 18-F and 19-F Tank Fill Grout 

Scale Up Test Summary.” Revision 0. Aiken, South Carolina: Savannah River National 

Laboratory. December, 2011. 

SRR-CWDA-2012-00170, Martin, B. “Tanks 18 and 19 Final Configuration Report for F-Tank 

Farm at the Savannah River Site.” Revision 0. Aiken, South Carolina: Savannah River 

Remediation, LLC. June, 2013. 

SRR-CWDA-2012-00172. Ross, S. R. Memorandum to J. Shaffner Transmitting Tank 18F 

Grout Pour Videos. August 17, 2012. 

SRR-LWE-2012-00036, Thaxton, G.D. “Tank 18F and 19F Closure Assurance Plan.” Revision 

0. Aiken, South Carolina: Savannah River Remediation, LLC. March 28, 2012. 

SRR-LWE-2012-00217, Frazier, S.L. “Tanks 18 and 19 Final Configuration Report Inputs.” 

Revision 1. Aiken, South Carolina: Savannah River Remediation, LLC. January 16, 2013. 

SRR-LWP-2012-00034, Guilherme, J.B. “SRR Subcontractor Surveillance Plan Furnishing and 

Delivery of Tank Closure Grout (TK 18/19).” Aiken, South Carolina: Savannah River 

Remediation, LLC. May 9, 2012. 
- 3 - 

Summaries of Technical Reports: 

SRNL-RP-2011-00977, Stefanko and Langton (2011), Tanks 18-F and 19-F Grout Fill 

Engineering and Performance Requirements, Rev. 0.

The report provides the physical property requirements for the tank closure grout. An 

abbreviated list of requirements provided by Savannah River Remediation (SRR) F-Area Tank 

Farm (FTF) Engineering was used for evaluating candidate grout formulations and as screening 

criteria for designing improved formulations. The list of requirements was expanded as grout 

formulation work progressed. Included in this report are brief explanations of selected tests 

used to support and/or parameterize the FTF Performance Assessment 

(SRS-REG-2007-00002, Rev. 1) and the bases for the requirements. 

The physical property requirements include those for fresh grout and for cured grout. Fresh 

grout properties include slump-flow, static flow, air content, set time, bleed water, maximum 

temperature during curing, and slurry pH. Cured grout properties include alkalinity, reducing 

capacity, compressive strength, effective porosity, dry bulk density, and particle density. The 

required pH and Eh are ≥12.4 and ~−200 to −400 mV, respectively. No specific requirements for 

effective porosity, dry bulk density, and particle density are given; these are to be measured or 

calculated for input to the FTF Performance Assessment. Dimensional stability, shrinkage, and 

cracks also are mentioned as important cured grout physical properties. No numerical 

requirements are specified for these properties, but the report acknowledges that tank closure 

grout with minimal cracks (as low as reasonably achievable) caused by shrinkage and/or 

expansion is desired. The report states that “test methods and mix designs are currently being 

developed to quantify shrinkage for the base case grout and to explore opportunities for 

reducing chemical shrinkage inherent to portland cement materials.” 

Numerical requirements for transport properties of cured grout also are listed in the report. 

These properties include effective diffusion coefficient (≤ 8.0×10−7

 cm2/s [≤ 8.6×10-10 ft2/s]), 

tortuosity (≤ 20), saturated hydraulic conductivity Ksat (≤ 3.6×10−8

 cm/s [≤ 1.2×10-9 ft/s]), and Kds 

(varies with radioelement and redox condition). 

SRNL-L3100-2011-00180, Langton and Stefanko (2011), Bulk Fill Grout Recommendations for 

Tanks 18-F and 19-F.

This document is a short interoffice memorandum that summarizes the test results described 

more fully in SRNL-STI-2011-00551, which is discussed below. The memo recommends three 

grout mix formulations for filling Tanks 18F and 19F1

. The recommended mix numbers are 

LP#8-16, LP#8-16C, and LP#8-20. Mix LP#8-16C is similar to LP#8-16 but has less fly ash and 

quartz sand and contains a shrinkage compensating component. LP#8-20 is similar to LP#8-16 

but has more quartz sand and ViscoCrete® admixture and less water and Kelco-Crete®

admixture. 

SRNL-L3100-2011-00180 appears to predate the completion of SRNL-STI-2011-00551, which 

is discussed below. In contrast to SRNL-L3100-2011-00180, SRNL-STI-2011-00551 

 

1

 The DOE documents cited in this report refer to Tanks 18 and 19 of the FTF with various monikers (e.g., 

“Tanks 18-F and 19-F”, “TK 18/19”, and “Tanks 18F and 19F”). The various monikers are synonymous.
- 4 - 

recommends only one grout mix formulation, LP#8-16, for filling Tanks 18F and 19F. That 

formulation was used in a tank fill grout scale up test described in SRNL-STI-2011-00749. 

SRNL-STI-2011-00551, Stefanko and Langton (2011), Tanks 18 and 19-F Structural Flowable 

Grout Fill Material Evaluation and Recommendations.

Tests were conducted to identify a single (all-in-one) grout to stabilize and isolate the residual 

radionuclides in Tanks 18F and 19F, provide structural stability to the closed tanks, and serve 

as an inadvertent intruder barrier. The use of a single grout is different from the three layer 

concept (stabilizing, structural, and capping grouts) used in Tanks 17F and 20F. The new grout 

mix designs that were tested were based on the flowable zero bleed structural fill mix that was 

used for the in-situ decommissioning of SRS P- and R-Reactor facilities. New admixtures for 

adjusting grout flow properties were also tested because the admixture products used in 

previous grouts are no longer available. Also, the sources of cement and fly ash have changed 

from previous tests and currently available portland cements contain up to 5% by weight 

limestone. 

Table 1-2 of SRNL-STI-2011-00551 provides a link between grout attributes, physical 

properties, and engineering parameters. For example, to meet the grout attribute of high 

reducing capacity over the long term, at least 210 lb [95 kg] of slag per cubic yard of reducing 

grout is specified as an engineering parameter. To satisfy the attribute of low water infiltration 

through the in-place grout over the long term, a saturated hydraulic conductivity, Ksat, less than 

or equal to 3.66 × 10−8

 cm/s [1.20 × 10-9 ft/s] is specified as an engineering parameter. Because 

LP#8-20 and LP#8-16 have the same quantities of cement and slag cement, Langton and 

Stefanko (SRNL-STI-2011-00551; Tables 3-4 and 4-1) estimate that the two mixes have 

identical thermal properties, i.e., adiabatic temperature rise for complete hydration of 34 °C 

[93 °F], specific heat of 1,080 J/kg·K [0.258 Btu/lb], and thermal conductivity of 2.5 W/m·K 

[1.44 Btu/hr-o

F-ft]. The aforementioned thermal properties were not experimentally verified. 

Langton and Stefanko estimate density for the two mixes, listed in Table 3-4 of 

SRNL-STI-2011-00551, that may not agree with the bulk and particle densities listed in 

Table 3-5 for LP#8-20 and LP#8-16. When this document was published, the moisture retention 

function was also still under development. The only data available were volumetric water 

contents at pressures ranging between 0 and 15 bars [0 and 15 atm] (Table 3-6); water contents 

for pressures between 15 and 45 bars [15 and 44 atm] were not available. 

Tests involved measurements of fresh grout properties, including slump flow, set time, bleed 

water, unit weight, air content, and cured grout properties, including compressive strength, 

saturated hydraulic conductivity, moisture retention characteristics, and heat of hydration. The 

tests used mix designs that contained sand only or both sand and 3⁄8 in [9.53 mm] granite 

“pea gravel” as aggregates. All mix designs tested included portland cement, blast furnace 

slag, and fly ash, as well as the additives ViscoCrete® and Kelco-Crete®. The report mentions 

that special test forms were designed and instrumented to evaluate dimensional changes 

(shrinkage and expansion) as a function of time, temperature, and humidity. However, the 

report states that tests of shrinkage and bonding to steel forms and tests of formulations with 

shrinkage compensating admixtures were postponed by tank closure project personnel. 
- 5 - 

The tests indicate that including 3⁄8 in [9.53 mm] gravel, rather than using sand as the only 

aggregate, improved mixing and homogeneity, flow, and compressive strength. Mix 

formulations in the LP#8 series, which was based on the self-leveling, flowable structural fill 

grout used for in-situ decommissioning of SRS P- and R-Reactor facilities, were selected as 

candidates for fillings Tanks 18F and 19F based on fresh grout properties, compressive strength 

at 28 days, and water-to-cement ratio. Based on additional data on adiabatic temperature rise 

and hydraulic conductivity, the report recommends mix LP#8-16 for scale-up testing and 

inclusion in the procurement specification for furnishing and delivering tank closure grout for 

Tanks 18F and 19F. The LP#8-16 mix design is provided in Table 1. 

A later design change documented in C-DCF-F-01524, which is discussed below, revised the 

amount and commercial brand of admixtures (high range water reducer and viscosity modifier) 

to be used in the tank grout. 

SRNL-STI-2011-00564, Stefanko and Langton (2011), Tank 18 and 19-F Tier 1A Equipment Fill 

Mock Up Test Summary, Rev. 0.

The report documents the results of equipment fill mock up testing DOE conducted to evaluate 

placement issues related to grouting equipment that will be left in Tanks 18F and 19F. This 

equipment includes the Advance Design Mixer Pump (ADMP), transfer pumps, transfer jets, 

standard slurry mixer pumps, equipment support masts, sampling masts, dip tube assemblies, 

and robotic crawlers. DOE grouted the equipment in place to fill voids in the equipment and 

eliminate vertical fast pathways for water infiltration. 

The mock up tests focused on filling the ADMP and pipes 1 in [3 cm] and larger in diameter. 

DOE considered these configurations to be representative and bound the majority of the 

equipment that will be left in the tanks. The ADMP is a particular concern because of its 55-ft 

[16.8-m] length, large size, and complicated flow path through its support column. Initially, for 

the ADMP mock up test, a 1 ft [0.3 m] × 1 ft [0.3 m] × 8 ft [2.4 m] Plexiglas scaled mock up test 

form was constructed, with 18 chambers to represent the ADMP internal volumes. However, 

because of limitations in material availability, grout batching capability, and logistics of filling an 

8 ft [2.4 m] high test form, the initial form was cut in half and only the bottom 4 ft [1.2 m] test 

form, partitioned into 9 chambers with Plexiglas dividers/shelves, was used for the test. Pipe 

grouting mock up tests used 5 ft [1.5 m] long, 1 in [3 cm] and 2 in [5 cm] diameter pipes oriented 

vertically. 

The mock up tests used two grout formulations, T1a-62.5FA and T1a-75FA, which are 

summarized below (see summary of SRNL-STI-2011-00592). For the ADMP mock up test, the 

grout was gravity fed into the test form using a funnel, with the grout level maintained at the 9 in 

[23 cm] mark of the funnel to keep a relatively constant fill rate. Ten batches of grout were used 

to fill the form. The first five batches used the T1a-62.5FA grout formulation and the second five 

batches used the T1a-75FA formulation. After filling, all chambers except one were observed to 

Table 1. Tanks 18F and 19F Bulk Fill Material Recommendation 

Mix 

Number

Cement 

Type 

I/II

Slag 

Grade 

100

Fly Ash 

Class F

Type G 

Shrinkage 

Compensating 

Component

Sand 

Quart

z

Gravel 

No. 8 

Water

HRWR 

SIKA®

 

ViscoCrete®

2100

VMA 

Diutan Gum 

Kelco-Crete®

DG

lb/yd3 gal/yd3 fl oz /yd3 gram/yd3

LP#8-16 125 210 363 0 1790 800 48.5 41 200 
- 6 - 

be completely filled with grout. The report speculates that the dividing plate between two of the 

chambers may not have been level. For the pipe filling tests, the pipes were filled from the top 

down through a funnel and also from the bottom up by discharge through a tube inserted into 

the pipes. In the latter case, the inserted tube was connected to a grout pump. The test results 

indicate that the pipes were completely filled using both fill methods. 

The report documents that the grout mixes had high viscosities (honey like) and appeared 

sticky. The report notes that the potential for chamber flooding was apparent during the mock 

up test even with the ability of the staff to manually control the fill rate and to observe through 

the Plexiglas for possible signs of near flooded conditions. It is also reported that chamber 

flooding did occur at the higher flow rate used in the test and the displaced air could not vent 

through a flooded chamber, which resulted in overfilling and rejection (spill) of grout around the 

funnel and air vent. From these observations and recognizing the long and tortuous path and 

long fill time involved in filling the 55-ft [16.8-m] long column in the actual ADMP, the report 

recommended that a lower viscosity grout be considered to increase the likelihood of complete 

filling of the ADMP and reduce the risk of spills caused by chamber flooding. 

SRNL-STI-2011-00592, Stefanko and Langton (2011), Tanks 18 and 19-F Equipment Grout Fill 

Material Evaluation and Recommendations, Rev. 0.

Laboratory tests were conducted to identify a grout formulation for filling bulk waste and heel 

waste removal equipment that will remain in Tanks 18F and 19F. This equipment includes 

mixer pumps, transfer pumps, transfer jets, equipment support masts, sampling masts, and dip 

tube assemblies. The internal void spaces in the equipment were to be grouted to eliminate fast 

pathways and slow water infiltration to the residual waste material on the tank floor. General 

performance requirements for the equipment fill grout are: (1) the grout must be alkaline and 

chemically reducing (i.e., contain slag), (2) the grout must be sufficiently flowable to fill 

equipment voids and pipes ≥ 1 in [2.54 cm] in diameter, (3) the grout must form a solid material 

upon curing, and (4) the grout must provide a barrier to infiltrating water, i.e., minimize vertical 

pathways. Table 2-1 in the report lists the test methods used to characterize the properties of 

fresh grout slurries, including initial and static flow, air content, set time, bleed water, maximum 

temperature during curing, slurry pH, static working time, and dynamic working time. Table 2-2 

in the report lists the test methods to characterize the cured grout properties, which include 

compressive strength, effective porosity, dry bulk density, pH, reducing capacity, effective 

diffusion coefficient, and saturated hydraulic conductivity. Tables 2-1 and 2-2 also list the target 

values for the grout properties and the bases for those target values. 

Initial tests were conducted using a grout formulation that previously was tested (in 2008) for 

filling cooling coils (2-in [5-cm] schedule 40 piping) in HLW tanks. This grout is a mixture of 

Masterflow® cable grout, Grade 100 blast furnace slag, and water. The test results indicate that 

the cooling coil mix generated high temperatures (> 100 °C [> 212 °F]) due to exothermic 

hydration reactions and exhibited flow behavior that was more suited for pressure grouting than 

for gravity filling. Therefore, the cooling coil grout was modified to reduce the amount of heat 

generated and to increase flowability. Class F fly ash was substituted for up to 75 % by weight 

of the Masterflow® 816 cable grout and the water-to-cementitious material ratio was increased. 

Based on the additional tests, two mix formulations (referred to as T1a-62.5FA and T1a-75FA) 

are recommended in the report for the Advanced Design Mixer Pump (ADMP) Tier 1A 

equipment fill mock up test. Both mixes have lower heats of reaction than the cooling coil grout 

and produce cured grouts that meet or exceed the strength and saturated hydraulic conductivity 
- 7 - 

requirements for Tank 18F and 19F bulk grout fill. The T1a-75FA mix generates less heat 

during curing than the T1a-62.5FA mix, but the latter is slightly more fluid than the former. The 

report states the T1a-62.5FA is the preferred formulation because the ease of filling tank 

equipment is more important than curing temperature, which is considered manageable using 

engineering controls. 

SRNL-STI-2011-00749, Stefanko and Langton (2011), Tank 18-F and 19-F Tank Fill Grout 

Scale Up Test Summary, Rev. 0.

SRNL-STI-2011-00749 documents the results of a 4 yd3

 [3 m3] bulk fill scale up test on the grout 

formulation that was recommended for filling Tanks 18F and 19F. The test was intended to 

demonstrate the proportioning, mixing, and transportation of material that was produced in a 

full-scale ready mix concrete batch plant. In addition, the material produced for the scale up test 

was characterized with respect to fresh properties, thermal properties, and compressive 

strength as a function of curing time. 

In addition, a 1 yd3

 [0.8 m3] insulated plywood form with an insulated lid was poured with the 

bulk fill grout for measuring semi-adiabatic temperature rise. The box was lined with a plastic 

sheet and thermocouples were installed at different locations in the box. The box was filled with 

grout that was discharged directly from a truck, covered with an insulated lid, and then left in 

place for approximately one month as temperature readings were taken. 

The slump flow per ASTM International (formerly the American Society for Testing and 

Materials) Standard C1611 (ASTM, 2009) was 25.5 in [64.7 cm] for material measured in FTF, 

which is within the acceptable range in the tank fill procurement specification 24 to 28 in [61 to 

71 cm] and corresponded to values measured in the laboratory. The set time was 7.5 hours, 

which is less than the 24 hours required to sustain next day operations and to meet the 

production requirement for filling the waste tanks. The average compressive strength of the 

samples that were cured for 28 days was 2,800 psi [19 MPa], which meets the >2,000 psi 

[14 MPa] engineering and FTF Performance Assessment requirement (SRS-REG-2007-00002 

Rev. 1). The peak temperature in the grout occurred after 82 hours with a semi-adiabatic 

temperature rise of 23 °C [41 °F], which was considered to meet the objective for grout that can 

be mass placed. 

C-SPP-F-00055, Forty (2011), Furnishing and Delivery of Tank Closure Grout, Rev. 2.

C-SPP-F-00055 is a detailed listing of the procurement specifications for furnishing and delivery 

of tank closure grout, including trial batching to demonstrate the production grout will meet the 

specification requirements. ASTM International (formerly the American Society of Testing and 

Materials) and American Concrete Institute (ACI) standards and specifications are generally 

specified. The three mix designs (LP#8-16, LP#8-16C, and LP#8-20) recommended in SRNLL3100-2011-00180 are listed as the initial mix designs, although a later document (C-DCF-F01524), which is discussed below, eliminates LP#8-16C and LP#8-20 from the list of grout 

mixes to be supplied. The batch plant capacity is specified as (i) sustained average capacity of 

400 yd3

/day [300 m3/day] through a five day work week and (ii) a sustained average capacity of 

70 yd3

/day [50 m3/day] for an eight hour period. The estimated duration of grout production is 

six months and the estimated quantity of grout is 17,064 yd3

 [13,046 m3], based on filling Tanks 

18F and 19F. 
- 8 - 

C-TRT-F-00005, Ganguly (2012), Technical Summary Report for Tanks 18F and 19F Closure 

— Initial Trial Batching (U), Rev. 0.

Tank grout trial batching of vendor supplied grout mix and its components was performed in 

March 2012, prior to the start of production grouting to fill Tanks 18F and 19F, to demonstrate 

the capability of the vendor to produce tank closure grout in compliance with the tank fill grout 

specification requirements. This report documents the results of trial batching and initial 

qualification testing. The tests demonstrate that the grout supplier can produce and deliver 

grout in accordance with the tank closure grout specification requirements. 

The report discusses five action items that resulted from discrepancies between the vendor test 

data and the grout specification requirements. These discrepancies apparently were identified 

during two previous assessments of vendor supplied grout. The report states that additional 

information supplied by the vendor was satisfactory such that the grout supplier is considered 

able to produce and deliver grout in accordance with the specification requirements. 

One deficiency identified in a previous assessment (and discussed in Appendix I of the report) 

pertains to the lack of 16-day test data for Potential Alkali Reactivity per ASTM Standard C1260 

on coarse aggregate. To resolve this deficiency, the vendor noted that (i) 5- to 14-day Potential 

Alkali Reactivity test data for the coarse aggregate indicate the average length of expansion is 

very insignificant (0.04 percent) such that a 16-day test will have no significant adverse effect on 

the grout mix quality, and (ii) because the coarse aggregates came from the same quarry that 

was certified in 2006, no new testing on the aggregates was performed. SRS concludes that 

based on the additional information the vendor provided, the supplied aggregates are 

acceptable for use in the grout mix. 

C-DCF-F-01524, Ganguly (2012), Revise Tanks 18F & 19F Closure Grout Specification. 

This document describes the following changes to the Tanks 18F and 19F closure grout 

specification: 

• ASTM 5971 (Standard Practice for Sampling Freshly Mixed Controlled Low-Strength 

Material) and ASTM 4832 [Standard Test Method for Preparation and Testing of 

Controlled Low-Strength Material (CLSM) Test Cylinders] were replaced with 

ASTM C172 (Standard Practice for Sampling Freshly Mixed Concrete) and ASTM C31 

(Standard Practice for Making and Curing Concrete Test Specimens in the Field). The 

specified ASTM standards were replaced because the selected grout mix, which was 

selected after laboratory and field mock-up tests, behaves more like high flow concrete 

with small aggregates, instead of a controlled low-strength material. 

• The previous specification included grout mix component specification for the base mix 

formulation LP#8-16 and alternative formulations LP#8-16C, and LP#8-20. Because 

only LP#8-16 was verified through field testing, the specifications for LP#8-16C and 

LP#8-20 were deleted from the revised grout specification document. 

• The amount and commercial brand of admixtures (high range water reducer and 

viscosity modifier) to be used in the tank grout were changed. 
- 9 - 

C-DCF-F-01527, Forty (2012), Revise Tanks 18F & 19F Closure Grout Specification for Testing 

Samples. 

This document describes a change in the required method for sampling tank grout that is 

delivered to the site. ASTM Standard C172 requires that samples be obtained by collecting two 

or more portions taken at regularly spaced intervals during discharge of the middle portion of the 

batch and combining them into one composite sample. In the revised procedure, only single 

portion samples will be taken after 0.8 yd3

 [0.6 m3] has been discharged from the truck. 

Because samples will be taken at a station at the top of the hill away from the hoppers, the 

revised sampling procedure will facilitate traffic flow, worker safety, and ensure grout quality. 

The revised procedure is justified on the basis of tests comparing the compressive strength and 

slump flow of single portion samples and composition samples. The tests indicate that there 

was no variation in the slump flow between the two sample types and only a slight variation in 

compressive strength. The test results are included in the document. 

SRR-LWP-2012-00034, Guilherme (2012), SRR Subcontractor Surveillance Plan Furnishing 

and Delivery of Tank Closure Grout (TK 18/19).

This document lists the Quality Control (QC) surveillance and Quality Assurance (QA) 

assessment activities SRR Construction Quality Services will perform in its oversight of the 

subcontractor during furnishing and delivery of tank closure grout for Tanks 18F and 19F. 

QC surveillance includes: (i) inspection of production mixes, (ii) grout inspection and testing, 

(iii) material testing and control, (iv) verification of measuring and test equipment calibration, 

(v) batch procedures, and (vi) receipt inspection. QA assessment will verify conformance to the 

procurement specification, procedures, and applicable codes and standards. 

SRR-LWE-2012-00036, Thaxton (2012), Tank 18F and 19F Closure Assurance Plan, Rev. 0.

This closure assurance plan identifies process and documentation requirements and provides a 

strategy to ensure the process requirements are met and the required documentation is 

generated and retained during grouting of Tanks 18F and 19F. The plan is considered to be a 

tool for DOE to ensure that Tanks 18F and 19F are closed successfully, while meeting all 

regulatory process and documentation requirements. 

The plan lists the requirements and documentation for the: (i) initial trial batch qualification; 

(ii) surveillances required prior to production grouting; (iii) SRR point of delivery sampling and 

acceptance of delivery; (iv) production grout sample testing; (v) supplier certification, testing, 

and documentation requirements for grout components during production grouting; 

(vi) surveillances of grout supplier and testing laboratories during production grouting; 

(vii) in-tank surveillance of production grouting; and (viii) in-tank surveillance of grouting of 

abandoned equipment. Attachment 1 of the document provides a crosswalk between the 

closure assurance requirements and the FTF Performance Assessment requirements. 

Alexander (2012), Placement of Grout Tank 18 Center Riser, Work Order No. 01087939–16 and 

Patton (2012), Placement of Grout Tank 19 Center Riser, Work Order No. 01087938–15.

These work orders provide detailed lists of activities to be performed during grouting of 

Tanks 18F and 19F through the center risers. The work orders estimate that it would have 

taken approximately eight lifts to the tank spring line for a total of approximately 7,200 yd3

 
- 10 - 

[5,500 m3

] of grout, then the dome would be filled with an additional ~1,140 yd3 [~871 m3] of 

grout, for a tank fill total of approximately ~8,340 yd3

 [~6380 m3]. The work orders include 

safety precautions and limitations that were to be followed (including radiation control 

procedures) during grouting. 

Isherwood (2012), Placement of Grout Tank 18 Various Equipment Locations, Work Order No. 

01087939–17 and Patton (2012), Placement of Grout Tank 19 Various Equipment Locations, 

Work Order No. 01087938–16.

These work orders provide detailed lists of activities that were to be performed during grouting 

of equipment and risers for Tanks 18F and 19F. For Tank 18F, the risers include East Riser, 

West Riser, Northeast Riser, Northwest Riser, Southeast Riser, Southwest Riser, Center Riser, 

and Mechanical Cleaning Riser. For Tank 19F, the risers include East Riser, West Riser, 

Northeast Riser, Waste Transfer Containment Enclosure (near northeast riser), Northwest 

Riser, Southeast Riser, and Southwest Riser. The work orders include safety precautions and 

limitations that were to be followed (including radiation control procedures) during grouting. 

SRR-CWDA-2012-00127, Ross (2012), Memorandum Regarding Tank 18F Grouting Operation 

Videos

This memorandum transmitted to NRC video recording of Tanks 18F grout pours and an in-tank 

daily inspection in response to an action item identified during the onsite observation visit that 

occurred on June 12, 2012 (The onsite observation report is available in ADAMS at Accession 

No. ML12191A210). The approximately 35 hours of video footage that was transmitted 

captures 12 days of grouting operations for Tank 18F from April 12, 2012 through June 28, 

2012. The document identifies whether the initial four hours or the last four hours of grout 

pouring operations were video recorded for each specified day. 

SRR-LWE-2012-00217, Frazier (2013), Tanks 18 and 19 Final Configuration Report Inputs,

Rev. 1

This report documents data from the grouting of Tanks 18F and 19F for future reference and 

includes deviations from the configuration described in the Closure Module (SRR-CWDA-2010-

00003). The data include important dates in which grouting began and ended, average 

compressive strength test results, bulk fill and equipment fill grout volume estimates, and 

differences in the final configurations of Tanks 18F and 19F from those that are spelled out in 

the Closure Module (SRR-CWDA-2010-00003). DOE reports average compressive strength 

test results from a total of 1,161 test cylinders. The average of the results for the compressive 

strength tests that were performed after a 28-day cure is 2,880 psi [19.86 MPa] which exceeded 

the design compressive strength of 2,000 psi [14 MPa]. The average of the 90-day 

compressive strength test results is 4,680 psi [32.3 MPa]. DOE also reports that the volume of 

bulk fill grout was estimated at 8,343 yd3

 [6,379 m3] per tank while actual bulk fill volumes are 

8,094.5 yd3

 [6,188.7 m3] and 8,090 yd3 [6,185 m3] for Tank 18F and 19F respectively. 

SRR-CWDA-2012-00170, Martin (2013), Tanks 18 and 19 Final Configuration Report for F-Tank 

Farm at the Savannah River Site, Rev. 0.

This report documents completion of operational closure of Tanks 18F and 19F and the final asbuilt configuration of the closed waste tanks and any field conditions that differ from those 
- 11 - 

described in the Closure Module (SRR-CWDA-2010-00003). The document summarizes 

isolation and grouting activities that have been completed and monitoring that will occur during 

the interim period between operational closure of Tanks 18F and 19F and the final closure of 

FTF. In terms of grouting, this report summarizes bulk tank fills, equipment fills, and 

modifications to waste tank tops to accommodate riser grouting. Details on grouting of Tanks 

18F and 19F are provided in Work Orders No. 01087939 and 01087938, respectively. 

For final bulk grout fill conditions, the report compares actual grout volumes to an estimated 

volume of 8,343 yd3

. [6,379 m3]. The actual volumes were estimated from the number of grout 

trucks and an assumption of 8 yd3

 [6 m3] of grout per truck, which was not verified for each 

truck. For Tanks 18F and 19F, as first reported in SRR-LWE-2012-00217, the actual grout bulk 

fill volume is approximately 8,094 yd3

 [6,188 m3] and 8,090 yd3 [6,185 m3] respectively. This 

report states that quality control of the grout production was implemented in accordance with 

C-SPP-F-00055. During grouting of both tanks, over 900 grout test cylinders were collected. 

The average 90-day compressive strength of the grout cylinders, as first reported in SRR-LWE2012-00217, is 4,680 psi [32.3 MPa], which is greater than the 2,000 psi [14 MPa] described in 

the Closure Module (SRR-CWDA-2010-00003). The report documents one bulk fill deviation for 

actual conditions from the Closure Module, namely that the Tank 18F ventilation cross-tie is a 

6-in [15-cm] diameter pipe with no jacket rather than a 4-in [10-cm] diameter pipe in a 6-in 

[15-cm] diameter jacket as described in the Closure Module. 

For final equipment grout fill conditions, the report compares estimated grout fill volumes to 

actual grout fill volumes for in-tank equipment. The report cautions that estimated fill volumes 

rely on assumptions about internal void space and potential grout flow paths. Certain 

equipment contained long, narrow, tortuous flow paths that debris may have potentially blocked 

resulting in less grout fill than estimated, such as is posited for the grout fill volume in the 

standard mixer slurry pump in the Tank 18F East Riser that is lower (approximately 37%) than 

estimated. The report also documents four equipment fill deviations for actual conditions from 

the Closure Module (SRR-CWDA-2010-00003): 

1. Two 2-in [5-cm] diameter vertical stainless steel pipes in the center riser of Tank 18F 

that were not previously identified were found to extend from above the tank top to near 

the tank floor, approximately 44 ft [13.4 m] below the tank top. The pipes were filled with 

5 gallons [19 L] and 8 gallons [30 L] respectively compared to an estimated 8.7 gallons 

[32.9 L] of fill based on an assumed 50-ft [15-m] length. 

2. The Tank 19F Northeast Riser thermowell, which is listed in Table 7.2-2 of the Closure 

Module (SRR-CWDA-2010-00003), was removed prior to grouting. 

3. Bubbler tubes and a pipe containing a conductivity probe were identified in the Tank 19F 

Northwest Riser, but are not listed in Table 7.2-2 of the Closure Module 

(SRR-CWDA-2010-00003). The tubes and pipe were grouted when the riser was filled 

with grout. 

4. Two 1.5-in [3.8-cm] diameter, approximately 5-ft [1.5-m] long stainless steel pipes 

associated with spray wash equipment were identified in the Tank 19 Northeast Riser, 

but are not listed in Table 7.2-2 of the Closure Module (SRR-CWDA-2010-00003). One 

pipe was filled with 4 gallons [15 L] and the other with 1/3 gallon [1-1/3 L] of grout.

 
- 12 - 

NRC Evaluation: 

Grout Formulation:

With regard to the final grout formulation (LP#8-16) selected for Tanks 18F and 19F, the 

following table compares the recommended grout mix formulation (SRNL-STI-2011-00551) with 

that assumed in Denham’s (WSRC-STI-2007-00544) conceptual model of waste release (and 

Eh and pH transitions assumed in the FTF Performance Assessment [SRS-REG-2007-00002, 

Rev. 1]). 

Table 2 shows that the amount of slag in LP#8-16 is the same as the value Denham used in his 

calculations. The LP#8-16 portland cement amount is higher than Denham’s, which would 

result in higher pH buffering capacity (fly ash is approximately the same). The water-tocementitious materials ratio in LP#8-16 is lower than in Denham’s, which would result in lower 

porosity and hydraulic conductivity. The measured effective porosity of the LP#8-16 grout 

reported in Table 3-5 of SRNL-STI-2011-00551 is 0.21, versus 0.266 used in the FTF 

Performance Assessment (SRS-REG-2007-00002, Rev. 1). Also, the measured Ksat of the 

LP#8-16 specimens ranged from 3.1 × 10−10 to 2.1 × 10−9

 cm/s [1.0 × 10-11 to 6.9 × 10-11 ft/s], 

lower than the requirement of 3.6 × 10−8

 cm/s [1.2 × 10-9 ft/s]. Thus, the initial chemical and 

expected hydraulic properties of the LP#8-16 formulation used to fill Tanks 18F and 19F are 

generally consistent with FTF Performance Assessment assumptions.2

 However, the 

measurements are on short-term properties of the grout and do not address the physical and 

chemical evolution of the tank grout over time. Additionally, FTF Performance Assessment 

conceptual model assumptions like matrix versus fracture flow in waste release modeling that 

affect chemical transition times and potential for tank grout by-pass are not explicitly addressed 

in the DOE grout specifications. The distinction between flow through cracks in the grout 

monolith versus flow through the grout monolith matrix is important to performance because 

DOE assumes in its reference case (i.e., Case A) that infiltrating groundwater reacts with the 

tank grout and is chemically altered by those interactions. In the FTF Performance 

 

2

 A subsequent report by Denham (SRNL-STI-2012-00087) used a grout formulation consistent with the 

LP#8-16 formulation used in Tanks 18F and 19F.

Table 2. Comparison of Assumed Versus Final Specifications for Tanks 18F and 19F 

Fill Grout 

Grout component Reducing grout mix formula†

 Recommended LP#8-16 all-in-one 

grout mix formula 

Portland cement 75 lb/yd3 125 lb/yd3

Fly ash 375 lb/yd3 363 lb/yd3

Slag 210 lb/yd3 210 lb/yd3

Sand 2,300 lb/yd3 1,790 lb/yd3

Gravel (No. 8; 3/8”) 0 800 lb/yd3

Water 501 lb/yd3 405 lb/yd3 [48.5 gal/yd3] 

Additives NA ViscoCrete®: 41 fl.oz/yd3

Kelco-Crete®: 200 gram/yd3

Calculated w/c ratio 0.759 0.580 

† WSRC-STI-2007-00544 
- 13 - 

Assessment (SRS-REG-2007-00002, Rev. 1), the chemistry of the conditioned groundwater 

flowing through the tank grout helps maintain the low solubility and release of key radionuclides 

from the residual waste. If flow were primarily through cracks that by-pass the tank grout, the 

release rates of key radionuclides could be significantly greater and could occur much earlier in 

time than assumed in DOE’s FTF Performance Assessment (SRS-REG-2007-00002, Rev. 1). 

Stefanko and Langton (SRNL-STI-2011-00551) acknowledged shrinkage could provide fast flow 

pathways and listed minimizing the potential for cracking as a grout selection criterion. 

However, no testing of shrinkage or cracking of the recommended grout mixture was performed. 

The recommended grout mixture had a lower Ksat than assumed in the FTF Performance 

Assessment (SRS-REG-2007-00002, Rev. 1). While a lower Ksat is beneficial with respect to 

bulk matrix flow, grouts with lower hydraulic conductivity will tend to have less water flow 

through the matrix and greater potential flow through cracks, annuli, and voids, if present. 

Stefanko and Langton (SRNL-RP-2011-00551) recommended that final development and 

testing of shrinkage compensating all-in-one mix design should be conducted to help mitigate 

the inherent potential for fast pathways. NRC conducted onsite observations on June 12, 2012 

(ML12191A210) to observe Tanks 18F and 19F grouting and on September 26-27, 2012 

(ML12299A190) to follow-up on items related to Tank 18F and 19F grouting that arose from the 

June observation. When questioned by NRC staff regarding plans for additional testing, DOE 

indicated that its plans for shrinkage testing would become clearer in the Liquid Waste 

Performance Assessment Maintenance Plan, which DOE indicated was planned for March 

2013. NRC reviewed the Performance Assessment Maintenance Plan 

(SRR-CWDA-2013-00049, Rev. 1), but was unable to gain additional information regarding 

plans for testing and development of new formulations to address tank grout shrinkage. During 

an onsite observation to observe grouting of Tanks 5F and 6F, which was conducted on August 

27-28, 2013 (The onsite observation report is in preparation and will be issued later this year.), 

NRC inquired about plans for testing of new formulations to address tank grout shrinkage. DOE 

indicated that it currently does not have plans to conduct shrinkage testing, but may pursue 

tests in the future. NRC staff concur with Stefanko and Langton’s recommendations for testing 

of admixtures and implementation of measures to help mitigate tank grout shrinkage and will 

continue to evaluate this technical issue in future onsite observations. 

In C-TRT-F-00005, Ganguly mentions that alkali-silica reaction will have no significant adverse 

effect on grout mix quality based on short-term tests (≤ 16 days) of alkali-silica reactivity (ASR). 

ASR is a process whereby reactive aggregates break down under exposure to the highly 

alkaline pore solution in concrete, which can result in significant expansion and, in some cases, 

cause cracking of concrete. At the June 12, 2012, onsite observation (ML12191A210), NRC 

staff communicated its concern with the potential formation of cracks in the tank grout due to 

ASR. This concern arose because the grout being used to fill Tanks 18F and 19F included 3⁄8-in 

[9.53-mm] granite “pea gravel” as aggregates, instead of using only sand aggregate as 

described in the DOE’s FTF Performance Assessment document (SRS-REG-2007-00002, Rev. 

1), and because of recent observations of concrete cracking at the Seabrook nuclear power 

plant in Seabrook, New Hampshire. In that facility, granite aggregates also were used in the 

concrete mix. ASR is a slow process and its occurrence at Seabrook became evident only 

decades after the plant was constructed. The Tanks 18F and 19F grout fill mix contain less 

Portland cement than the concrete mix used at Seabrook and likely would be less susceptible to 

ASR. Nevertheless, NRC staff is concerned that DOE’s criterion for acceptance of vendor 

supplied granite aggregate relies on short-term alkali reactivity tests (ASTM Standard C1260), 

which is unlikely to predict the occurrence of ASR over the very long period of performance for 
- 14 - 

compliance with the performance objective specified at 10 CFR 61.41. NRC staff recommends 

that DOE consider conducting tests to evaluate potential ASR in tank grouts and its potential 

effect on long-term performance of the engineered barrier system. 

Furthermore, Stefanko and Langton (SRNL-STI-2011-00551) indicated that sources of cement 

and fly ash have changed from previous tests and currently available portland cements contain 

up to 5 % by weight limestone. Substitution of up to 5 % by weight limestone in commercially 

available portland cement could vary the minerals that form upon cement hydration and the pH 

buffering capacity of the grout from the grout mix considered in DOE’s FTF Performance 

Assessment (SRS-REG-2007-00002, Rev. 1). At the June 12, 2012 onsite observation, NRC 

staff communicated its concern that a reduction in the amount of portland cement in the grout 

mix would lower the pH buffering capacity of the grout and could affect the timing of release of 

key radionuclides (ML12191A210). NRC staff recommends that DOE evaluate the effect of 

limestone substitution in portland cement on the pH buffering capacity of the grout and the 

release of key radionuclides. 

NRC staff was initially concerned that the slump flow specification of 24 to 28 in [61 to 71 cm] 

provided in SRNL-RP-2011-00977 was not sufficient to enable the grout to completely fill the 

tanks and seal around the internal tank fixtures. This concern arose from observations of an 

intermediate-scale grout monolith specimen constructed by the Center for Nuclear Waste 

Regulatory Analyses (CNWRA) using a previously proposed SRS tank grout formulation 

(Walter et al., 2010) with a slump flow specification of 28 to 30 in [71 to 76 cm]. The thinner 

CNWRA-prepared grout specimen was not self-leveling and the grout surface had a slope 

ranging from 4 to 8 percent with a 3 m [10 ft] radius and 0.76 m [2.5 ft] fill thickness. 

Furthermore, the CNWRA grout specimen was also characterized by the presence of “lobes”3

, 

which were accentuated by the limited ability of the tank grout to self-level and which were due 

to the incomplete lateral delivery of tank grout from a centrally located placement point outwards 

toward the specimen walls. In addition to concerns regarding the ability for DOE to fill the tanks 

with reducing grout, NRC was also concerned with the presence of grout mounds and flow 

lobes such as these because Dinwiddie, et al. (2011; 2012) indicated that the lobe interfaces, as 

well as interfaces between successive lifts, are subject to shrinkage and could form high 

hydraulic conductivity zones through the monolith. 

Following observations of potential grout segregation, which is discussed in detail below, NRC 

staff is less concerned about the ability to fill tanks and the creation of higher hydraulic 

conductivity zones, which may be associated with lobe interfaces, through the monolith. Rather, 

NRC staff is now more concerned with the potential for segregation and lower quality grout to be 

delivered to the periphery of Type IV tanks enhancing shrinkage along the tank wall and 

focused flow around the reducing grout leading to less conditioning of infiltrating water than if 

water flowed primarily through the grout. 

During the June 12, 2012, onsite observation, NRC staff inquired about the extent of mounding 

at the center of the tanks and the ability to completely grout the tank at its periphery 

(ML12191A210). DOE indicated that additional access points may be created to ensure that the 

tanks are completely filled; however, no additional access points were created. NRC staff also 

observed the appearance of grout lobes in DOE-supplied video that documents the grouting of 

 

3 A grout flow lobe is a fan-shaped mass of grout that forms on a slope by the changing direction of flow.
- 15 - 

Tanks 18F and 19F and expressed concerns about the potential for flow paths to be created 

between grout lobes and successive lifts. NRC requested DOE to provide a video record of 

tank filling that would be beneficial to NRC staff understanding of (i) the evolution of grout 

mounding and lobe formation over time and (ii) the potential for lower quality grout to form near 

the tank walls due to the use of process water (and resultant higher water-to-cement ratios of 

grout in contact with collected water at the tank walls) at the start of each day of grouting or 

segregation of grout components as the grout flows toward the periphery of the tanks. As part 

of their ongoing presence at the site, officials from the State of South Carolina’s Department of 

Health and Environmental Control indicated a willingness to share information related to these 

grout features observed during their future inspections. South Carolina’s Department of Health 

and Environmental Control provided video footage obtained from grouting of Tank 19F to NRC 

staff during the September 27-28, 2012, onsite observation visit (ML12299A190) 

On August 17, 2012, DOE provided NRC a video record of tank filling 

(SRR-CWDA-2012-00127). Subsequently, NRC and DOE conducted a teleconference 

(ML13127A291) to discuss NRC observations from the video. Video footage of grout 

emplacement in Tank 18F suggests that the zero-bleed grout formulation may have been 

handled in such a way during grouting that water segregation occurred. NRC staff in reviewing 

the video footage from Tanks 18F (SRR-CWDA-2012-00127) and 19F, which was provided by 

the South Carolina Department of Health and Environmental Control (ML12299A190), made the 

following observations to DOE in a teleconference on May 1, 2013 (ML13127A291): 

• Material tested to be zero-bleed may later be handled in such a way that excessive 

water segregation occurs and this excessive water segregation is believed to have been 

observed in grouting videos. 

• Vibration during transport and dropping concrete from height during placing is known to 

exacerbate the production of segregation water. 

• Excess water that segregates from grout is more flowable than grout and was observed 

to preferentially flow to the tank perimeter. 

• Excess water was recognized in grouting video by its low albedo (i.e., dark color) and 

flowability. 

• Segregated water was not tremie flushwater (i.e., clear, uncolored) 

• Grout matrix porosity and permeability may increase radially due to shedding of 

segregated water to zones near tank perimeter. 

• Shrinkage gaps at the tank perimeter may be significant. 

• Grout mounded high in the tank center will hydrate in a relatively dry microclimate, 

whereas, grout submerged under standing water at tank perimeter will hydrate in a much 

wetter microclimate; because of this, grout properties are not likely to be uniform along 

the tank radius. 
- 16 - 

As a follow-on action from the teleconference, NRC provided DOE these main points from 

reviewing the video footage. Also, as a follow-on action, DOE agreed to respond to NRC at a 

later date, either in writing or via teleconference. 

With respect to equipment grouting, DOE provided information during the June 12, 2012, onsite 

observation (ML12191A210) regarding its process for equipment grouting, as well as the 

implementation of its equipment grouting plans during grouting of Tanks 18F and 19F. During 

the September 26-27, 2012, onsite observation (ML12299A190), NRC staff requested 

documentation of DOE’s equipment fill mock-up test report (SRNL-STI-2011-00564). The 

mock-up test focused on the ADMP because of its large size and complexity of the flow path in 

it. The ADMP has a 55-ft [16.8-m] long shaft, but the mock-up test utilized a 4-ft [1.2-m] long 

test form. The test results indicated potential problems with chamber flooding, which could 

result in incomplete filling of the void spaces in the ADMP. NRC staff is concerned the ADMP 

mock-up test provided insufficient data to support a conclusion that the ADMP void spaces 

could be completely filled with the T1a-62.5FA or T1a-75FA grout and eliminate a potential 

vertical flow path through the grouted tank. NRC will continue to monitor the equipment 

grouting and testing of the recommended equipment grout fill formulation for future tanks. The 

NRC staff will also continue to evaluate the potential for annuli to form around internal tank 

fixtures such as grouted abandoned equipment and cooling coils that may lead to preferential or 

by-passing flow around or through the tank grout. 

In SRNL-STI-2011-00551, the density estimate of 2.21 g/cm3

 [138 lb/ft3] listed in Table 3-4 for 

LP#8-16 is not consistent with the values of measured dry bulk density and calculated particle 

density listed in Table 3-5. NRC staff will follow-up with DOE regarding this discrepancy. The 

NRC staff also will follow-up with DOE in regard to the characteristics of the final and completed 

moisture retention function (i.e., volumetric water contents at pressures ranging between 15 and 

45 bars [15 and 44 atm]). 

Thermal Evaluation:

Stefanko and Langton (SRNL-STI-2011-00749) concluded that the adiabatic temperature rise of 

23 °C [41 °F] observed in the 1 yd3

 [0.8 m3] grout scale up test meets the objective for grout that 

can be mass placed. The NRC staff believes this conclusion lacks sufficient technical basis. 

The amount of grout that is emplaced in SRS tanks is much larger than 1 yd3

 [0.8 m3], which 

would result in a much higher temperature rise than was observed in the grout scale up test. In 

addition, tank grouting involves sequential grout pours that would generate multiple and 

overlapping heat pulses. A more detailed thermal analysis that considers the specific grout pour 

sequence and geometry to determine the potential for thermal cracking of the tank grout would 

provide additional model support. 

DOE did not measure the thermal properties of the selected grout mix, LP#8-16, to validate the 

adiabatic temperature rise for complete hydration that Stefanko and Langton 

(SRNL-STI-2011-00551) estimated. Measuring the adiabatic temperature rise and thermal 

properties of the LP#8-16 mix would ensure a complete documentary record. 

QA Evaluation:

The DOE quality assurance plan, as described in SRR-LWE-2012-00036, is clear and, if 

implemented properly, should ensure that Tanks 18F and 19F are closed according to plan, 
- 17 - 

while meeting all regulatory process and documentation requirements. As part of NRC 

monitoring activities, the NRC staff will continue to evaluate during its onsite observation visits 

whether the DOE quality assurance plan is being implemented effectively. 

Final Configuration:

The final configuration of Tanks 18F and 19F, as described in SRR-CWDA-2012-00170, and the 

reported deviations from the Closure Module (SRR-CWDA-2010-00003) are clear. The actual 

grout bulk fill volumes for each tank were each approximately 3% less than initially estimated for 

Tanks 18F and 19F. While the volumes are generally in good agreement on a percentage 

basis, DOE does not document for the record expected causes for the bulk fill grout deviations 

to mitigate potential concern over the formation of preferential pathways. This information could 

also be used to improve future volume estimates. Compressive strength testing indicated that 

the strength of the emplaced bulk fill grout exceeds the compressive strength assumed in the 

FTF Performance Assessment (SRS-REG-2007-00002, Rev. 1). In contrast to bulk grout fill, 

the Final Configuration report (SRR-CWDA-2012-00170) does provide documentation regarding 

potential causes of significant deviations in equipment grout fill volumes in the Final 

Configuration Report, however, estimates of remaining void volumes are not provided.

Teleconference or Meeting: 

NRC staff plans to discuss further with DOE the observations of apparent segregation during 

grouting of Tanks 18F and 19F. In a teleconference on May 1, 2013, NRC staff presented key 

points regarding its review of video footage during grouting of Tanks 18F and 19F 

(ML13127A291). As a follow-on action, NRC provided DOE its main points from reviewing the 

video footage. Also, as a follow-on action, DOE agreed to respond to NRC at a later date, 

either in writing or via teleconference. 

Follow-up Actions: 

At a May 1, 2013, teleconference (ML13127A291), DOE agreed to respond to NRC staff’s main 

points from its review of the Tank 18F and 19F grouting video footage. 

NRC staff will continue to monitor DOE’s grout formulations under Monitoring Factors 3.3, 

“Shrinkage and Cracking”, and 3.4, “Grout Performance” listed in NRC staff’s FTF Monitoring 

Plan (ML12212A192) focusing on the technical concerns listed in this review report. 

Open Issues: 

No open issues result from this technical review. However, insufficient information is provided 

to address the likelihood for preferential pathways to form through the grout monolith including 

those from shrinkage, cracking, grout seams, and voids. DOE testing of and efforts to mitigate 

grout shrinkage have been postponed. NRC will continue to follow-up on this technical issue 

under Monitoring Factor 3.3, “Shrinkage and Cracking” (See ML12212A192). 

Conclusions: 

The NRC staff concludes that performance requirements for grout formulations recommended 

and tested for Tanks 18F and 19F closure are generally consistent with bulk, initial properties 
- 18 - 

assumed in DOE’s FTF Performance Assessment (SRS-REG-2007-00002, Rev. 1). However, 

the NRC staff also concludes that DOE has not provided sufficient information and testing to 

adequately invalidate alternative conceptual models reflecting preferential flow through the tank 

grout monolith that might result from grout shrinkage and cracking. 

Thus, NRC considers the following conclusion more significant for providing reasonable 

assurance that that the 10 CFR Part 61 performance objectives will be met. DOE indicated that 

it currently does not have plans to conduct shrinkage testing, but may pursue tests in the future. 

The NRC staff concur with Stefanko and Langton’s recommendations for testing of admixtures 

and implementation of measures to help mitigate tank grout shrinkage and will continue to 

evaluate this technical issue in future onsite observations as part of Monitoring Factor 3.3, 

“Shrinkage and Cracking” (ML12212A192). 

The NRC staff also considers the following five conclusions to be of lesser importance at this 

time than the aforementioned conclusion regarding shrinkage to providing reasonable 

assurance the performance objectives of 10 CFR Part 61 will be met. NRC believes that the 

following five conclusions are less significant at this time because they are related to features or 

processes that tend to promote or involve water flow through the grout leading to more chemical 

conditioning of the water than would likely occur should the water be focused along the tank 

wall. 

First, the NRC staff believes DOE’s conclusion that the temperature rise was sufficiently low for 

bulk grouting of Tanks 18F and 19F based on a 1 yd3

 [0.8 m3] bulk scale-up test and will 

continue to evaluate this technical issue in future onsite observations. A more detailed thermal 

analysis that considers the specific grout pour sequence and geometry to determine the 

potential for thermal cracking of the tank grout would improve model support. The NRC staff will 

continue to monitor DOE efforts to assess the potential for thermal cracking of the tank grout as 

part of Monitoring Factor 3.3, Shrinkage and Cracking” (ML12212A192). 

Second, DOE did not document in the Final Configuration Report (SRR-CWDA-2012-00170) 

expected causes for the bulk fill grout deviations to mitigate potential concern over the formation 

of preferential pathways. The Final Configuration Report does provide documentation regarding 

potential causes of significant deviations in equipment grout fill volumes, however, estimates of 

remaining void volumes are not provided (e.g., ADMP). This information could also be used to 

improve future volume estimates. NRC staff will continue to monitor DOE estimates of void 

volumes including whether there is additional information that would support a conclusion that 

the ADMP void spaces were completely filled as part of Monitoring Factor 3.3, “Shrinkage and 

Cracking” (ML12212A192). 

Third, the NRC staff will also continue to monitor void volumes in the emplaced grout to the 

extent information is available, the importance of alkali-silica reactivity on cementitious material 

degradation and the impact of limestone additions to the grout mix on pH buffering of water 

contacting the emplaced grout. This information would enhance DOE’s demonstration that the 

Part 61 performance objectives are met with reasonable assurance. 

Fourth, the NRC staff communicated its concern with the potential formation of cracks in the 

tank grout due to ASR. The NRC staff is concerned that DOE’s criterion for acceptance of 

vendor supplied granite aggregate relies on short-term alkali reactivity tests (ASTM Standard 

C1260), which is unlikely to predict the occurrence of ASR over the very long period of 
- 19 - 

performance for compliance with the performance objective specified at 10 CFR 61.41. 

Evaluating potential ASR in tank grouts and its potential effect on long-term performance of the 

engineered barrier system would improve model support for the performance of the grout and 

understanding of the potential for cracking of the grout. The NRC staff will continue to monitor 

DOE efforts to evaluate potential ASR and its potential effect on long-term performance under 

Monitoring Factor 3.3, “Shrinkage and Cracking” (ML12212A192). 

Finally, the NRC staff is concerned that the use of commercially-available portland cements in 

Tanks 18F and 19F that differ from the grout mix considered in the FTF Performance 

Assessment (SRS-REG-2007-00002, Rev. 1) because of substitution of up to 5% by weight 

limestone would lower the pH buffering capacity of the grout and could affect the timing of 

release of key radionuclides. Evaluating the effect of limestone substitution in portland cement 

on the pH buffering capacity of the grout and the release of key radionuclides improves model 

support for the modeling of chemical states and transitions of water contacting the residual 

waste. The NRC staff will continue to monitor DOE efforts to evaluate limestone substitution 

and its potential effect on long-term performance under Monitoring Factor 6.2, “Model and 

Parameter Support” (ML12212A192). 

 
- 20 - 

References: 

ASTM Standard 4832, 2010. "Standard Test Method for Preparation and Testing of Controlled 

Low Strength Material (CLSM) Test Cylinders." West Conshohocken, Pennsylvania: ASTM 

International. 2010. 

ASTM Standard 5971, 2007. " Standard Practice for Sampling Freshly Mixed Controlled LowStrength Material" West Conshohocken, Pennsylvania: ASTM International. 2007. 

ASTM Standard C31, 2012. "Standard Practice for Making and Curing Concrete Test 

Specimens in the Field." West Conshohocken, Pennsylvania: ASTM International. 2012. 

ASTM Standard C172, 2010. "Standard Practice for Sampling Freshly Mixed Concrete." West 

Conshohocken, Pennsylvania: ASTM International. 2010. 

ASTM Standard C1611, 2009. "Standard Test Method for Slump Flow of Self-Consolidating 

Concrete." West Conshohocken, Pennsylvania: ASTM International. 2009. 

ASTM Standard C1260, 2007. "Standard Test Method for Potential Alkali Reactivity of 

Aggregates." West Conshohocken, Pennsylvania: ASTM International. 2007. 

Dinwiddie, C.L., D.R. Bannon, M.K. Todt, G.R. Walter and M.M. Roberts. “Draft Fiscal Year 

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