UNITED STATES

NUCLEAR REGULATORY COMMISSION

WASHINGTON, D.C. 20555-0001

September 6, 2016

MEMORANDUM TO: Richard Chang, Acting Chief

Low-Level Waste Branch

Division of Decommissioning, Uranium Recovery,

 and Waste Programs

Office of Nuclear Material Safety

 and Safeguards

THROUGH: Christepher McKenney, Chief /RA/

Performance Assessment Branch

Division of Decommissioning, Uranium Recovery,

 and Waste Programs

Office of Nuclear Material Safety

 and Safeguards

FROM: Cynthia Barr, Senior Systems Performance Analyst /RA/

Performance Assessment Branch

Division of Decommissioning, Uranium Recovery,

 and Waste Programs

Office of Nuclear Material Safety

 and Safeguards

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

DOCUMENTATION RELATED TO TANKS 16H AND 12H 

GROUTING OPERATIONS WITH EMPHASES ON 

SPECIFICATIONS, TESTING, RECOMMENDATIONS AND 

PLACEMENT PROCEDURES (PROJECT NO. PRO0734)

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

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

grouting and closure of Tanks 16H in 2015 and 12H in early 2016. The focus of NRC’s 

technical review is grout formulations and specifications, testing, recommendations and 

placement procedures. NRC also revisits findings from previous technical review reports 

related to Tanks 18F and 19F grouted in 2012; as well as Tanks 5F and 6F grouted in 2013 

(Agencywide Documents Access and Management System (ADAMS) Accession No.

ML13269A365 and ADAMS Accession No. ML14342A784). This technical review can be tied to 

several monitoring factors listed in NRC’s combined F-Area and H-Area Tank Farm monitoring 

plan entitled “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 and H-Area Tank Farm 

Facilities in Accordance with the National Defense Authorization Act for Fiscal Year 2005” 

[available using ADAMS Accession No. ML15238A761] issued in October 2015. The Monitoring 

Plan discusses NRC’s approach to fulfilling its responsibilities under the National Defense 

Authorization Act for Fiscal Year 2005 to monitor DOE disposal actions to assess compliance 

with the Performance Objectives in 10 CFR Part 61, Subpart C, for DOE wastes (and 
R. Chang - 2 -

associated disposal facilities) found to be incidental to reprocessing. NRC’s Monitoring Plan 

lists the technical areas, which are the focus of NRC’s monitoring activities. This technical 

review supports NRC’s Monitoring (of) Factors 3.2 “Groundwater Conditioning via Reducing 

Grout,” 3.3, “Shrinkage and Cracking,” and 3.4, “Grout Performance” listed in the NRC’s 

Monitoring Plan, which are important to F-Area and H-Area Tank Farm Facility engineered 

barrier performance, as discussed in more detail in the evaluation section below.

The NRC staff concludes that performance requirements for the tank grout formulation 

recommended and tested for Tank 16H and 12H closure are generally consistent with initial bulk 

chemical and hydraulic properties assumed in DOE’s H-Area Tank Farm Facility Performance 

Assessment (PA) (SRR-CWDA-2010-00128). However, DOE assumes but has not provided 

sufficient information and testing to support its exclusion of shrinkage gaps, cracks, and other 

preferential flow pathways through the grout monolith from the reference case in DOE’s PA. 

These conclusions were also true for Tank 18F, 19F, 5F and 6F and DOE’s F-Area Tank Farm 

Facility PA.

The NRC staff expects DOE to provide additional information related to the extent and 

performance impact of tank grout 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) are met. As stated above, DOE assumes in the PAs for F- and 

H-Area that the grout does not shrink, crack or fracture in the base or reference case. Rather, 

the grout is assumed to degrade slowly with a subsequent increase in hydraulic conductivity of 

the grout matrix over time. This assumption is risk-significant because conceptually DOE 

assumes that the entire grout matrix is available to condition infiltrating groundwater to relatively 

low Eh (e.g., initially −470 mV) and high pH, which is necessary to maintain the low solubility of 

key radionuclides. For the tank grout to condition infiltrating water to relatively low Eh and high 

pH, water must flow through and interact with the grout. In contrast, if flow is concentrated 

along fast pathways through the tank grout (e.g., gaps between the tank wall/internal tank 

components and tank grout, or shrinkage gaps, cracks and fractures in the grout), flow rates 

through the grout may be significantly faster and the extent of interaction between infiltrating 

groundwater and tank grout may be significantly less than assumed in DOE’s PAs, thereby 

hastening the time to transition to risk-significant solubility for certain key radionuclides. During 

its review of Tank 16H grouting video (SRR-CWDA-2015-00170), NRC staff also observed 

large-aperture cracks in grout that developed shortly after the grout had been placed in the Tank 

16H annulus. NRC staff expects DOE to provide additional information on the mechanisms for 

crack formation, including thermal cracking, for all grout monoliths, including those in Tanks 16H 

and 12H. NRC staff will continue to evaluate the potential for shrinkage- and cracking-induced 

preferential flow through the tank grout under MF 3.3, “Shrinkage and Cracking” (ADAMS 

Accession No. ML15238A761), as well as DOE’s assumptions regarding flow through the tank 

grout that influences the extent of groundwater conditioning in MF 3.2 “Groundwater 

Conditioning via Reducing Grout”.

During its review of Tank 16H grouting video (SRR-CWDA-2015-00170), NRC staff observed 

potential bleed water segregation of tank grout during placement that could enhance shrinkage 

along the periphery (i.e., at the wall) of the tank and result in inhomogeneous material properties 

affecting water percolation patterns through the monolith. The NRC staff continues to monitor 

the potential for segregation of grout bleed water and consequent impacts on future water flow 

through the grout monolith and waste release under Monitoring Factor 3.4, “Grout Performance”

because of its importance to the demonstration that the long-term closure of both F-Area Tank 
R. Chang - 3 -

Farm and H-Area Tank Farm tanks will meet 10 CFR Part 61, Subpart C, performance 

objectives for protection of the general population from releases of radioactivity, and protection 

of individuals from inadvertent intrusion. Tank 12H grouting video has not yet been requested 

by NRC, because DOE has only recently completed grouting of this tank. Therefore, NRC staff 

reaches only preliminary conclusions on Tank 12H grouting in this technical review report.

The NRC staff will also continue to monitor void volumes in the waste tanks to the extent that

information is available (Monitoring Factor 3.4, “Grout Performance”); the importance of

alkali-silica reactivity on cementitious material degradation (Monitoring Factor 3.3, “Shrinkage 

and Cracking”); and the impacts on the (i) pH buffering capacity of tank grout and (ii) timing of 

release of key radionuclides that will derive from its Portland cement containing up to 5 wt 

percent limestone (Monitoring Factor 3.4, “Grout Performance”). It is NRC staff’s position that 

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

10 CFR Part 61, Subpart C are met.

Other conclusions unique to Tanks 16H and 12H grouting include the following:

• DOE should take reasonable measures to ensure a sufficient number of cement trucks 

are in rotation to optimize grout distribution throughout the tank and minimize mounding.

• More flowable clean cap grout used to fill remaining void space at the top of the Tank 

16H primary and annulus may have significantly different hydraulic properties compared 

to the rest of the bulk fill grout placed in the primary and annulus of Tank 16H. DOE 

should address the potential for either a capillary or permeability barrier to form due to 

the varying hydraulic conductivity of the clean cap and bulk fill grout used in Tank 16H.

• The results of the grout drop test report (RPT-5539-EG-0016) suggest the potential for 

segregation and bleed water production in the annulus of Tank 12H during initial 

grouting operations if grout was dropped into standing water. DOE should provide 

additional information regarding the quantity and performance impact of the presence 

standing water in Tank 12H during grouting.

• Lehigh Grade 120 slag used in the Tank 12H grout mix starting on the second day of 

grouting is expected to provide superior chemical performance compared to Holcim 

Grade 100 slag due to the higher activity index and increased reduction capacity. The 

compressive strength of the Grade 120 slag is also expected to increase due to a 

combination of small particle size and increased reactivity. DOE should evaluate 

differences in hydraulic conductivity between the Grade 100 and Grade 120 slag used to 

fill Tank 12H and any resulting performance impact.
R. Chang - 4 -

In this report, there is no significant change to the NRC staff overall conclusions from the F- and 

H-Tank Farm TERs regarding compliance of DOE disposal actions with the 10 CFR Part 61 

performance objectives.

Enclosure:

Technical Review of Documents Related

 to Tanks 16H and 12H Grout Formulations,

 Testing, Procedures, and Operations at the

 H-Area Tank Farm at the Savannah River Site
R. Chang - 4 -

In this report, there is no change to the NRC staff overall conclusions from the F- and H-Tank 

Farm TERs regarding compliance of DOE disposal actions with the 10 CFR Part 61 

performance objectives.

Enclosure:

Technical Review of Documents Related

 to Tanks 16H and 12H Grout Formulations,

 Testing, Procedures, and Operations at the

 H-Area Tank Farm at the Savannah River Site

DISTRIBUTION:

CBarr GAlexander CGrossman LParks RGladney MHeath

HFelsher CRidge JTappert AKock DPickett WIR Service List

DOE SRS Email List

ADAMS Accession No. ML16231A444

OFFICE NMSS NMSS NMSS NMSS NMSS

NAME CBarr TMoon JShaffner CMcKenney CBarr

DATE 8/19/2016 8/22/2016 8/24/2016 9/2/2016 9/7/2016

OFFICIAL RECORD COPY
Technical Review of Documents Related to Tanks 16H and 12H 

Grout Formulations, Testing, Procedures, and Operations at the

H-Area Tank Farm at Savannah River Site

Date: August 19, 2016

Reviewers:

Cynthia Barr, U.S. Nuclear Regulatory Commission (NRC)

Cynthia Dinwiddie, Southwest Research Institute®

General Grout Documents:

1. C-SPP-F-00055. Ganguly, A. “Furnishing and Delivery of Tank Closure Grout.” 

Revision 4. Aiken, South Carolina: Savannah River Remediation, LLC. 

December 20, 2012.

2. C-SPP-F-00057. McCord, J.B. “Furnishing and Delivery of Cooling Coil Grout Dry 

Feeds.” Revision 2. Aiken, South Carolina: Savannah River Remediation, LLC. 

July 2014.

3. RPT-5539-EG-0016 (SRRA051386-2-A). Diener, G. “Savannah River Remediation 

Tank Closure Grout Assessment Final Report” (Grout Drop Test Report). Revision 0. 

Barnwell, South Carolina: EnergySolutions. December 16, 2014.

4. SDDR No. 13182. “Section 3.2.3.3 States the Slag Cement Must Meet ASTM C989, 

Grade 100. This Slag is No Longer Available in the Southeast, U.S.A. Change 

Specification to Allow for the Use of ASTM 989, Grade 120 Slag. (Supplier Deviation 

Disposition Request).” Augusta, Georgia: Argos Ready Mix, LLC. March 30, 2015.

5. SRNL-STI-2012-00546. Cozzi, A.D. and B.R. Pickenheim. “Impact of Standing Bleed 

Water on Saltstone Placement.” Revision 0. Aiken, South Carolina: Savannah River 

National Laboratory. September 2012a.

6. SRNL-STI-2012-00576. Cozzi, A.D. and B.R. Pickenheim. “Impact of Standing Water 

on Saltstone Placement II - Hydraulic Conductivity Data.” Revision 0. Aiken, South 

Carolina: Savannah River National Laboratory. October 2012b.

7. SRNL-STI-2012-00578. Langton, C.A., et al. “Relationship Between Flowability and 

Tank Closure Grout Quality.” Revision 0. Aiken, South Carolina: Savannah River 

National Laboratory. October 2012.

8. USQ-HTF-2015-00300. Voegtlen, R.O. “Supplier Deviation Disposition Request 

(SDDR) Number 13182–Deviation from Specification C-SPP-F-00055, Revision 4

(Technical Review Package).” Revision 0. Aiken, South Carolina: Savannah River 

National Laboratory. September 10, 2015.
- 2 -

9. VSL-15R3740-1. Gong, W. et al. “Investigation of Alternate Ground Granulated Blast 

Furnace Slag for the Saltstone Facility (Final Report).” Revision 0. Washington, DC: 

Vitreous State Laboratory, The Catholic University of America. August 26, 2015.

10. WSRC-STI-2008-00172. Harbour, J.R., et al. “Closure of HLW Tanks—Formulation for 

a Cooling Coil Grout.” Revision 0. Aiken, South Carolina: Savannah River National 

Laboratory. April 2008.

11. WSRC-STI-2008-00298. Hansen, E.K. et al. “Closure of HLW Tanks—Phase 2, 

Full Scale Cooling Coils Grout Fill Demonstrations.” Revision 0. Aiken, South Carolina: 

Savannah River National Laboratory. June 2008.

Tank 18F and 19F Documents:

12. 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 1. 

Aiken, South Carolina: Savannah River National Laboratory. April 2013.

13. 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.

14. 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.

15. SRNL-STI-2011-00749. “Tank 18F and 19F Tank Fill Grout Scale Up Test Summary.” 

Revision 0. Aiken, South Carolina: Savannah River National Laboratory. 

December 2011.

16. SRR-CES-2012-00031. “Summary Report of the Equipment Grout Mock-up Test.” 

Revision 0. Aiken, South Carolina: Savannah River Remediation, LLC. April 13, 2012.

Tank 5F and 6F Documents:

17. 2013-NCR-15-WFC-0006. “F Tank Farm Grout - Tank 6 (Non-Conformance Report).” 

Aiken, South Carolina: Savannah River Remediation. October 2, 2014; 

USQ-FTF-2013-00317. “New Data – Use-As-Is Disposition of the Non-Conformance 

Report (NCR) 2013-NCR-15-WFC-0006 ‘F Tank Farm Grout – Tank 6.’ 

Non-Conformance Tank 6 Grout Water Content Higher than Allowed per 

C-SPP-F-00055, Rev. 4 ‘Furnishing and Delivery of Tank Closure Grout.’” Revision 0. 

Aiken, South Carolina: Savannah River Remediation. October 3, 2014; and 

tank grout batch tickets for September 19, 2013.

18. SRR-CWDA-2014-00015. Cantrell, J.R. “Tank 5 and 6 Grouting Project Lessons 

Learned.” Revision 0. Aiken, South Carolina: Savannah River Remediation. 

February 6, 2014.
- 3 -

19. SRR-LWE-2013-00214. Chandler, T.L. “Engineering Path Forward – Tanks 5 & 6: 

Record of Additional Grouting Actions. Revision 0. Aiken, South Carolina: Savannah 

River Remediation. February 10, 2014.

20. Work Order No. 01199254-65. “Tanks 5–6 Pump Standing Water in Risers.” 

Revision 0. Aiken, South Carolina: Savannah River National Laboratory. December 10, 

2013.

Tank 16H Documents:

21. C-SPP-Z-00012. Patel, R. “Vault 4 Clean Cap Grout (Procurement Specification).” 

Revision 1. Aiken, South Carolina: Savannah River Remediation, LLC. March 20,

2014.

22. SRR-CWDA-2013-00091. “Industrial Wastewater Closure Module for Liquid Waste 

Tank 16H, H-Area Tank Farm, Savannah River Site.” Revision 1. Aiken, 

South Carolina: Savannah River Remediation, LLC. April 2015.

23. SRR-CWDA-2014-00011. Smith, F.M. “Evaluation of Vendor Supplied Clean Cap 

Material for Saltstone Disposal Units.” Revision 0. Aiken, South Carolina: Savannah 

River Remediation, LLC. March 2014.

24. SRR-CWDA-2015-00096. Layton, M. “Unreviewed Waste Management Question 

Evaluation – Use Alternative Tank 16 Fill Grout (Per Specification C-SPP-Z-00012).” 

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

September 2015.

25. SRR-CWDA-2015-00100. “Evaluation of the Use of an Alternative Tank 16 Fill Grout

(Per Specification C-SPP-Z-00012) (Interoffice Memorandum to G.C. Arthur from 

M.H. Layton).” Revision 2. Aiken, South Carolina: Savannah River Remediation, LLC. 

September 2015.

26. SRR-CWDA-2015-00159. “Tank 16 Final Configuration Report for H-Tank Farm at the 

Savannah River Site.” Revision 1. Aiken, South Carolina: Savannah River 

Remediation, LLC. May 2016.

27. SRR-CWDA-2015-00160. “Evaluation of the Performance Assessment Impact of 

using an Alternative Fill Grout in the H-Area Tank Farm (Interoffice Memorandum to 

G.C. Arthur from M.H. Layton).” Revision 0. Aiken, South Carolina: Savannah River 

Remediation, LLC. January 4, 2016.

28. SRR-LWE-2014-00013. Walters, C.D. “Tank 16H Grout Strategy.” Revision 1. 

Aiken, South Carolina: Savannah River Remediation, LLC. January 6, 2015.

29. SRR-LWE-2014-000150. Ostler, M. “Tank 16-H Closure Assurance Plan.” Revision 0. 

Aiken, South Carolina: Savannah River Remediation, LLC. March 2015.
- 4 -

30. SRR-LWP-2014-00049. Sareen, H. “SRR Subcontractor Surveillance Plan Furnishing 

and Delivery of Tank Closure Grout (TK 16) (P.O. No. SRRA-064184-1).” Revision 0. 

Aiken, South Carolina: Savannah River Remediation, LLC. June 1, 2015.

31. SRR-TCR-2015-00024. “Tank 16 Grouting Lessons Learned (Interoffice Memorandum 

from B. Davis to L. Blackford and J. Williams).” Revision 0. Aiken, South Carolina: 

Savannah River Remediation, LLC. January 27, 2016.

32. Work Order No. 01324150-64. Fail, J.A. “TK Clos & Reg Cn to Perform Grout 

Prep/Grout Placement TK 16.” Revision 0. Aiken, South Carolina: Savannah River 

National Laboratory. August 22, 2014.

Tank 12H Documents:

33. LWO-LWQ-2016-00001. Thompson, J.W. “SRR Subcontractor Surveillance Plan 

Furnishing and Delivery of Tank Closure Grout (TK 12) (P.O. No. SRRA-064184-1).” 

Revision 0. Aiken, South Carolina: Savannah River Remediation, LLC. January 13, 

2016.

34. SRR-CWDA-2014-00086. “Industrial Wastewater Closure Module for Liquid Waste 

Tank 12H, H-Area Tank Farm, Savannah River Site.” Revision 0. 

Aiken, South Carolina: Savannah River Remediation, LLC. May 2015.

35. SRR-CWDA-2015-00057. “Evaluation of the Use of Grade 120 Slag Cement in 

Tank Closure Grout versus Performance Assessment Assumptions (Interoffice 

Memorandum to G.C. Arthur from M.H. Layton).” Revision 1. Aiken, South Carolina: 

Savannah River Remediation, LLC. August 27, 2015.

36. SRR-CWDA-2015-00088. Layton, M.H. “Unreviewed Waste Management Question 

Evaluation – Use of Grade 120 Slag in Tank Closure Grout.” Revision 0. Aiken, 

South Carolina: Savannah River Remediation, LLC. September 2015.

37. SRR-LWE-2012-00030. “Tank 12 Cooling Coil Flushing Strategy (Interoffice 

Memorandum to M.D. Buxton from S.J. Worthy and J.R. Tihey).” Revision 1. 

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

38. SRR-LWE-2014-00147. Chandler, T. “Tank 12H Grout Strategy.” Revision 1. 

Aiken, South Carolina: Savannah River Remediation, LLC. August 31, 2015.

39. SRR-LWE-2014-00161. Walters, C.D. “Tank 12 Internal Equipment Evaluation.”

Revision 0. Aiken, South Carolina: Savannah River Remediation, LLC. February 12,

2015.

40. SRR-LWE-2015-00032. Ostler, M. “Tank 12-H Closure Assurance Plan.” Revision 0. 

Aiken, South Carolina: Savannah River Remediation, LLC. April 2015.
- 5 -

41. SRR-LWE-2015-00048. Griffin, A.L. “Path Forward for Tank 12 Annulus Liquid 

Removal (Interoffice Memorandum to E. Patten et al. from A.L. Griffin and G.C. Arthur).” 

Aiken, South Carolina: Savannah River Remediation, LLC. Revision 0. July 7, 2015.

42. Work Order No. 01337683-33. Patton, G.W. “Placement of Bulk Fill Grout: Tank 12.” 

Revision 0. Aiken, South Carolina: Savannah River National Laboratory. April 29, 

2015. 
- 6 -

NRC Technical Reviews

Summaries of the primary documents related to Savannah River Site (SRS) Tank Farm grouting 

listed above are provided in Appendix A. Technical reviews of the grout-related documents 

listed above are the basis for NRC’s evaluation of SRS Tanks 18F, 19F, 5F, 6F, 16H, and 12H 

grouting and final configurations discussed below.

Evaluation

Tank Grout Formulation, Testing, Placement and Performance

Many of NRC staff’s concerns about the waste tank grout formulation that resulted from the

original technical review of Tank 18F and 19F grouting and subsequent review of Tank 5F and 

6F grouting operations remain at the time of this writing. This technical review, which is focused 

on Tank 16H and 12H grouting operations, summarizes remaining NRC staff recommendations 

from prior technical review reports and accounts for new information or changes to DOE’s 

approaches for Tank 16H and 12H and new non-conformances. To fill the primaries and annuli 

of Tanks 16H and 12H, DOE selected the same tank grout that had been used previously to fill

Tanks 5F, 6F, 18F, and 19F (C-SPP-F-00055, Attachment 5.5). The following discussion 

addresses grout flowability and mounding, specifications and testing, bleed water segregation, 

grout drop testing, shrinkage, groundwater in-leakage, non-conformances, alkali–silica reactivity 

(ASR), and thermal considerations for bulk fill tank and annulus grout.

Grout Flowability and Mounding

During a June 12, 2012, onsite observation visit, NRC staff inquired about the extent of grout 

mounding below the center riser, which was the only riser used to place grout into Tanks 18F 

and 19F, and the ability of DOE to completely fill waste tanks with grout at their periphery as a 

result of the mounding (ADAMS Accession No. ML12191A210). Although significant mounding 

was observed by NRC early during grouting of Tanks 18F and 19F, DOE did not indicate nor 

document any significant issues with filling the tanks. Void volume estimates were provided to 

NRC in the Final Configuration Report inputs (SRR-LWE-2012-00217), and that indicated 

approximately 3 percent less volume of grout was used compared to what was estimated to fill 

the tanks. For Type IV tanks, DOE places grout through a center riser, although when 

questioned by NRC, DOE indicated that it could create additional entry points into the tank, if 

access to the interior of the tanks for grouting was needed due to mounding (ADAMS Accession 

No. ML13269A365). Other important attributes of Type IV tanks are (1) the absence of cooling 

coils used in other tanks to cool the waste, and (2) the domed roofs of the tank vaults. The 

domed roofs of the tank vaults make it easier to fill the tank from the center riser. Cooling coils 

act as obstructions and thereby make it more difficult to clean waste from the bottom of the 

tanks as well as grout the tanks. Over four miles of cooling coils are present in SRS Tank Farm 

tanks with cooling coils (Type I, II, III, and IIIA tanks contain cooling coils). To completely fill 

tanks containing cooling coils with tank grout, DOE enhanced tank grout flowability by specifying 

a higher range of desirable slump flow values (C-SPP-F-00055, Revision 4, Attachment 5.5), 

which were achieved solely through the use of admixtures (high-range water reducer). 

Acceptable slump flow is obtained at the batch plant and 8.0 gal (30.3 L) of water is withheld to 

allow further slump adjustments through potential water additions after grout is delivered to the

site (per ASTM C94). During the October 2014 teleconference about Tanks 5F and 6F grouting 

operations (ADAMS Accession No. ML14330A037), NRC inquired about the process DOE uses 
- 7 -

to reach the desired slump through use of water additions and admixtures. DOE clarified how it 

provides immediate feedback to the Argos batch plant regarding slump flow test results at the 

beginning of the day when the trucks reach the site to achieve the desirable slump through 

addition of admixtures at the batch plant without the need to add additional water at the site. 

For Type I Tanks 5F and 6F, which were grouted in 2013, DOE used four risers as grout entry 

points (Risers 1, 3, 5, and 8) and noted no significant issues with filling void space at the top of 

the tank due to mounding in the Final Configuration Report with less than 2 percent deviation 

between estimated and actual bulk fill grout volumes (SRR-CWDA-2014-00020).

In 2015, DOE began grouting Tank 16H located in the H-Area Tank Farm Facility. During Tank 

16H grouting operations, problematic mounding of tank grout occurred beneath three of four 

grout-placement risers. Prior to the July 28–29, 2015, onsite observation visit, tank grout was 

last placed in the tank primary on July 21, 2015. Triple-degree temperatures were recorded 

nearby in Augusta, Georgia, on both July 20 and 21, 2015. Grout placement was temporarily 

halted on July 21, 2015 due to excessive mounding. DOE indicated that on that date, grout had 

mounded up to nearly the top of the tank beneath Risers 2, 6 and 8, with only inches to spare 

(ADAMS Accession No. ML15239A612). In contrast, approximately 2 ft (0.6 m) of space 

remained between the grout surface and the top of the tank below Riser 3 (ADAMS Accession 

No. ML15239A612). DOE attributed mounding in Tank 16H to high ambient summer 

temperatures that increased the set rate of fresh grout (ADAMS Accession No. ML15239A612), 

but later acknowledged the potential role that non-optimal grout delivery rates may have played 

(ADAMS Accession No. ML16167A237). To date, DOE has made no effort to establish a 

causative relationship or correlate ambient temperatures or grout placement rates with the Tank 

16H mounding phenomenon (ADAMS Accession No. ML16167A237), which if undertaken 

would improve understanding of contributing factors. DOE does not monitor in-tank 

temperatures (ADAMS Accession No. ML16167A237), which are expected to be dominated by 

the heat of hydration during grouting operations. While the tanks are located underground and 

are insulated from surface temperature fluctuations, DOE indicates that ventilation of the tanks

introduces ambient air into the tanks and could influence in-tank temperatures during grout 

hydration.

Because solidified mounds of grout beneath Tank 16H risers could block flow of fresh tank grout 

into the primary and leave open-air void volumes1 near the tank top, DOE decided to stop work 

to provide time to take corrective actions to mitigate the mounding issues in late July 2015. 

DOE evaluated various alternatives, including use of alternative formulations, use of alternative 

risers, and use of directional tremies, which could be used to deliver grout at an angle from 

Riser 3 (ADAMS Accession No. ML15239A612). During the July 28–29, 2015, onsite 

observation visit, DOE indicated that grout could be delivered to the Tank 16H primary through 

the 3′ 6′′ Riser (ADAMS Accession No. ML15239A612); however, review of inspection video 

collected on July 29, 2015, indicated that grout at that location had also nearly reached the top 

of the tank beneath the riser (SRR-CWDA-2015-00170). In the end, DOE decided to use a 

more flowable grout formulation to complete grouting of the Tank 16H primary and annulus. 

Clean cap grout that had been developed for use in Saltstone Disposal Facility (SDF) was 

selected as the more flowable grout. Clean cap grout is an aggregate-free grout used to cap 

waste monoliths at the SDF (C-SPP-Z-00012). Pozzolanic and cementitious material 

components include slag cement (45 weight percent), Class F fly ash (45 weight percent), and 

 1 DOE estimates that the tank was 94 percent full at the time when DOE temporarily stopped grouting operations 

to prevent plugging the grout access points into Tank 16H (SRR-CWDA-2015-00109).
- 8 -

Portland Type I/II cement (10 weight percent). Water is the only other ingredient (C-SPP-Z00012). NRC awaits information from DOE to describe the meaning of the term “TEMPER,” 

which was also listed as a “material” (ingredient) on one clean cap grout batch ticket for Tank 

16H (042239). 

During review of Tank 16H grouting video (SRR-CWDA-2015-00170), NRC staff observed that 

many cement trucks discharged tank grout at an overall rate of less than 1 cubic yard per 

minute, apparently due to temporary shut-downs or what DOE calls slow rolling. Slow rolling is 

the intentional intermittent discharge of grout executed to keep fresh grout flowing and thereby 

avoid plugging the slick line when cement trucks are slow to arrive due to unanticipated 

vehicular or traffic issues or to having an insufficient number of trucks in rotation (ADAMS 

Accession No. ML16111B174). SRNL-STI-2012-00578 indicated that increasing the grout 

delivery rate by using a higher capacity concrete/grout pump would result in better grout 

distribution throughout waste tanks, but according to DOE, no subsequent change to grout 

pump capacity was implemented, nor are there plans to do so in the future (ADAMS Accession 

No. ML16167A237). SRNL-STI-2012-00578 did not address mounding associated with slow 

rolling. The Tank 16H grout strategy indicated that having 8 to 10 cement trucks in rotation was 

ideal (SRR-LWE-2014-00013), whereas the Tank 12H grout strategy later clarified that a grout 

delivery rate of 8 to 10 trucks per hour (SRR-LWE-2014-00147) was ideal. Eight to 10 trucks 

per hour converts to 56 to 70 cubic yards per hour (assuming discharge of 7 cubic yards of 

grout per truck), in contrast with Section 3.6.1.2 of the procurement specification, which requires 

a sustained average delivery of 74 cubic yards per hour during an 8-hr work day (C-SPP-F00055, Revision 4). The Tank 16H grout strategy stated that “Lessons learned from previous 

tank closures identified the benefit of a minimal time gap between grout trucks during select lifts 

in the annulus and the primary tank.” DOE was unclear, however, on what “select lifts” were 

being referred to2

. Despite recommendations in SRR-LWE-2014-00013 and SRR-LWE-2014-

00147, grout delivery contracts to date have not specified a grout delivery frequency or 

minimum number of cement trucks in rotation. When questioned by NRC staff about the 

feasibility of establishing contractual obligations related to the supply of grout trucks in rotation, 

DOE indicated that such contractual obligations would lead to significantly higher costs, as 

batch plant demand can be high and DOE has to compete with other customers for grout trucks 

(ADAMS Accession No. ML16167A237). Instead, DOE contractors work with the batch plant to 

schedule tank grouting during weeks when the plant can supply more cement trucks to the tank 

closure effort (ADAMS Accession No. ML16167A237). DOE also noted that while issues with a 

less than optimal number of trucks in rotation occurred during Tank 12H grouting operations, no 

significant mounding issues occurred for Tank 12H (ADAMS Accession No. ML16167A237), 

implying that grout delivery rates are not the sole factor contributing to the phenomena 

experienced during Tank 16H grouting in the summer of 2015.

At the July 28–29, 2015, onsite observation visit, DOE discussed steps it could take to prevent 

early tank grout set up and ensure its flowability. These included (i) use of cooling water to 

keep grout temperatures lower, (ii) slick line (length) adjustments, and (iii) halting grouting 

operations when ambient temperature exceeds a threshold value. However, during a recent 

teleconference, DOE indicated that they have not yet placed constraints on grouting operations 

related to high ambient temperatures beyond rescheduling operations, such as occurred in 

August 2015, to protect workers from heat effects (ADAMS Accession No. ML16167A237). 

 2 NRC notes that relatively high grout discharge rates during annulus ventilation duct grouting would help ensure 

the ventilation duct is fully grouted particularly when grouting from outside the duct, as was the case for Tank 16H. 
- 9 -

NRC also concurs that, as stated in SRNL-STI-2012-00578, mounding beneath risers can be 

partially mitigated and grout distribution improved if a sufficient number of cement trucks are in 

rotation. Allowing grout to flow for only a few minutes followed by a temporary shutdown (slow 

rolling) results in the premature halt near the discharge point of flowing grout lobes3 and thereby 

constructs elevated grout mounds. In contrast, continuous discharge of an entire grout batch 

enables grout to continuously flow until a barrier (e.g., the tank wall) is reached. If each cement 

truck were to discharge continuously, there would be less grout buildup around the discharge 

zone and grout would be more evenly distributed throughout the waste tank. Mounding is

exacerbated when grout discharge from a single cement truck starts, stops and restarts. While 

elevated ambient temperatures may reduce the set time of grout, DOE has not shown that 

summer temperatures were the leading cause of problematic mounding in Tank 16H.

Tank Grout Specifications and Testing

Tank type differences impact the grout placement approach and, potentially, grout performance. 

Tanks 5F, 6F, 12H and 16H contain many more internal tank obstructions (e.g., cooling coils)

than did Tanks 18F and 19F, and have flat, not domed, roofs. The grout specification for 

Tanks 5F, 6F, 12H, and 16H (C-SPP-F-00055, Revision 4) differed from that of Tanks 18F and 

19F (C-SPP-F-00055, Revision 2) only in that a greater slump flow range was specified to 

enhance grout flowability in tanks containing carbon steel cooling coils. DOE achieved higher 

slump flow by increasing the dose of high-range water-reducer ADVA Cast 575 (W.R. Grace & 

Co., Cambridge, Massachusetts) to 40 or 41.25 fluid oz per cubic yard (ADAMS Accession No. 

ML13267A452; SRR-CWDA-2013-00026, Attachments 3 and 4); however, 40 fluid oz/cubic 

yard is the maximum amount allowed by the tank grout specification (C-SPP-F-00055, Revision 

4, Attachment 5.5). NRC staff reexamined batch tickets provided by DOE for Tanks 18F, 19F, 

5F, 6F, and 16H to better understand how admixture dosages have varied during the various 

tank grouting operations (Table 1). During Tank 16H grouting operations, the dose of ADVA 

Cast 575 used per batch slightly exceeded the amount specified in C-SPP-F-00055 (Revision 4, 

Attachment 5.5). Hydration stabilizer RECOVER (W.R. Grace & Co., Cambridge, 

Massachusetts) dosages also varied, but viscosity modifier EXP 958 (W.R. Grace & Co., 

Cambridge, Massachusetts) dosages have remained constant at the maximum value allowed 

(Table 1). It is worthwhile to note that while the use of high-range water-reducer ADVA 575 has 

increased to achieve greater flowability, the viscosity modifying admixture (VMA), EXP 958 

dosage has not changed although VMAs are used to counter-balance the use of high-range 

water-reducers, which at higher quantities can lead to excessive bleed water segregation.

Table 1. Evolution of Admixture Dosages Used to Batch Tank Grout.

Admixture Dose in Fluid Ounces per 8-cubic-yard Batch

Procurement Specification Tank 18 Tank 19 Tank 5 Tank 6 Tank 16

ADVA 575 80–320 160 160 320 320 330

RECOVER As Required 30 30 50–60 50–60 30–60

EXP 958 Up to 330 330 330 330 330 330

The Tank 16H Final Configuration report summarized results of tank grout bleed-water testing; 

although most of the tank grout batches met the zero-bleed requirement (C-SPP-F-00055, 

 3

A grout flow lobe is a single fan- or channel-shaped mass of grout that forms on a grout mound as a 

result of changing discharge or changing direction of flow
- 10 -

Revision 4), some did not (SRR-CWDA-2015-00159). A supplier deviation disposition request 

(SDDR No. 13307) addressed the two highest bleed water test results, which were 3.3 and 

8.9 percent (SRR-CWDA-2015-00159). Following DOE’s evaluation, the SDDR was 

dispositioned as “use as is” (SRR-CWDA-2015-00159). NRC staff will request that DOE 

provide documentation associated with SDDR No. 13307 for review, and will continue to monitor 

the extent of bleed water segregation in tank grouting operations. DOE also provided NRC with 

five accepted grout batch tickets, including two batch tickets for clean cap grout (discussed 

below), and five rejected grout batch tickets (SRR-CWDA-2016-00031). Reasons given for 

rejecting grout batches were slump flow test results that were too low or too high, poor mixing, 

and segregation (SRR-CWDA-2016-00031). 

The aforementioned mounding of tank grout beneath three grout-placement risers in Tank 16H 

resulted in the unanticipated decision to complete Lifts 5 and 6 primary tank and annulus 

grouting operations with more flowable clean cap grout (C-SPP-Z-00012), which is an 

aggregate-free grout commonly used for leveling and filling headspace to cap the top of 

saltstone monoliths at the SDF (SRR-CWDA-2015-00109; SRR-CWDA-2015-00170). Clean 

cap grout has desirable fresh grout properties such as high flowability and appropriate reductive 

capacity (SRR-CWDA-2013-00091; SRR-CWDA-2015-00109). Unlike tank grout, however, 

clean cap grout is a low-bleed formulation (SRR-CWDA-2015-00109), not a zero- or virtually 

zero-bleed formulation.

Tank grout was designed to provide the following desirable physical and chemical properties: 

(i) high compressive strength (greater than 2000 psi) and (ii) high degradation resistance to 

provide stability; and (iii) high pH (e.g., initially assumed to be 11.1 in the HTF PA and grout 

specification is >12.1), (iv) low hydraulic conductivity (e.g., initially assumed to be 2.1 × 10−9

cm/s in the HTF PA), (v) relatively low porosity (assumed to be 0.21 in the HTF PA), (vi) low 

effective diffusion coefficient (e.g., initially assumed to be 5 × 10−8 cm2

/s in the HTF PA) and 

(vii) low Eh (e.g., initially assumed to be −0.47 V in the HTF PA) to limit migration of 

contaminants after operational closure (SRR-CWDA-2013-00091; SRR-CWDA-2015-00160). 

The HTF PA stated that “the entire tank is assumed to be filled with [tank] grout; therefore 

structural failure (i.e., collapse) is not considered.” The HTF PA assumes that tank grout 

has adequate compressive strength [i.e., minimum of 2000 psi (138 bars) at 28 days 

post-placement, per HTF PA Table 3.2-9 (SRR-CWDA-2010-00128)], to withstand the 

overburden load on each tank4

, thereby providing stability upon closure and a physical barrier 

that will discourage intruders. To confirm that this minimum strength was achieved for tank 

grout placed into Tank 16H, 28-day testing of 272 grout specimens collected at the point of 

delivery was performed by DOE (SRR-CWDA-2015-00159). The Tank 16H final configuration 

report discussed an associated deviation from the grout specification that requires test cylinders 

 4 Although DOE indicates that the compressive strength of the tank grout is adequate to withstand the overburden 

load on each tank, it is not clear to NRC that the tank grout, which is not expected to be fully bonded to the tank 

and vault, would initially be relied on to accept the load of overlying surface materials, including an engineered 

cover system to be placed over the tank farms. The reinforced concrete vault will initially be relied on to withstand 

the overburden load on each tank until such time that the vault fails. When discussing site stability during the July 

2015 onsite observation (ADAMS Accession No. ML15239A628), NRC similarly noted that a bounding structural 

analysis might consider the mass of the tank grout without the associated stiffness of a solid, grout filled monolith, 

because the tank grout is not expected to create a solid monolith with the tank/vault given the potential for 

shrinkage and cracking.
- 11 -

be maintained for 28 days in a controlled humidity and temperature environment. The deviation 

occurred when an equipment failure resulted in a 7-hour window during which temperatures 

exceeded the specification by up to 2 °C (3.6 °F) (SRR-LWE-2015-00085). Nevertheless, all 

tested tank grout cylinders had compressive strengths greater than the design 28-day 

compressive strength of 2000 psi (138 bars) and the average 28-day compressive strength of 

Tank 16H tank grout was 2,788 psi (192 bars). NRC does not consider the equipment failure 

and resulting temperature deviation a significant issue with respect to the compressive strength 

testing.

Because placement of clean cap grout in the Tank 16H primary and annulus was not anticipated 

during the planning stage, there was no requirement to collect specimens or conduct ASTM C39

compressive strength testing of clean cap grout placed into Tank 16H. However, slump flow 

data were obtained, according to batch tickets #042239 and #042345, for clean cap grout 

batches discharged into the primary and annulus, consistent with the procurement 

specification’s (C-SPP-Z-00012) requirement of a field acceptance test for ASTM C1611 slump 

flow to be in the range of 26–38 in (66–97 cm). Later, even though the Tank 12H subcontractor 

surveillance plan (LWO-LWQ-2016-00001) anticipated potential placement of clean cap grout

into Tank 12H, DOE established no requirements for ASTM C39 compressive strength testing of 

it. Whereas high-quality tank grout has high compressive strength [>2000 psi (>138 bar)] to 

provide waste tank stability, and low permeability (2.1 × 10−9 cm/s) and relatively low porosity 

(21 percent) to limit percolation of water through the grout matrix (SRR-CWDA-2010-00128), 

clean cap grout prepared with a low water-to-premix ratio has adequate compressive strengths 

(SRNL-STI-2012-00558; see also SRR-CWDA-2015-00160), slightly higher mean hydraulic 

conductivity values (2.2 × 10−9 cm/s) (SRR-CWDA-2015-00160), but much higher porosity 

values (~50 to 60 percent) (SRNL-STI-2012-00558; PNNL-20706) by 28-days post-placement, 

such that its use in Tank 16H may yet enhance the water percolation rate through the grout 

matrix to the contamination zone. SRR-CWDA-2015-00100 documented DOE’s evaluation of 

the impact of switching from placement of tank grout to clean cap grout in the midst of placing 

final grout Lifts 5 and 6 into the Tank 16H primary and annulus (SRR-CWDA-2015-00096). 

DOE concluded that because use of clean cap grout would minimize remaining void space at 

the top of the tank and be limited to less than 10 percent of the original tank volume, tank 

stability and the inadvertent intruder barrier provided by the two-component grout monolith 

would be maintained (SRR-CWDA-2015-00100). During the May 17, 2016, teleconference with 

NRC (ADAMS Accession No. ML16167A237), DOE clarified that most of the grout placed into

Lift 6 in the Tank 16H annulus was tank grout (i.e., 25 or 26 out of 31 truckloads or 81 to 84 

percent of the Lift 6 volume). The different characteristic hydraulic properties of tank grout and 

clean cap grout suggests that a hydrologic barrier (such as a capillary or permeability barrier) 

may develop at the interface between underlying tank grout and overlying clean cap grout, but 

potential barriers such as these and their implications on performance have not been addressed 

by DOE (SRR-CWDA-2015-00100; ADAMS Accession No. ML16167A237). 

As of April 2015, DOE was preparing to switch from use of Grade 100 ground granulated blast

furnace slag cement in the tank grout formulation (C-SPP-F-00055) to Grade 120 (SRR-LWE2015-00032). The switch to use of Grade 120 occurred on the second day of Tank 12H 

grouting in January 20165

. In contrast with DOE’s position that the hydraulic conductivity of tank 

 5 Prior to the issuance of this TRR, DOE clarified via email on August 15, 2016, that Grouting of Tank 12 was 

initiated on January 19, 2016, with Lift 1 in the primary (see slide #31 of the OOV presentation material, SRRCWDA-2016-00009 [ADAMS Accession No. ML16111B232]). Lift 1 was completed the next day, January 20, 2016. 
- 12 -

grout will not be impacted by the change in slag grade (SRR-CWDA-2015-00057), differences in 

particle size and other factors might produce a grout with a different hydraulic conductivity. Had 

DOE used the same Grade 120 slag-based grout throughout the entire tank, a more 

homogeneous grout monolith would have developed. NRC will follow-up with DOE with respect 

to any performance impact associated with use of two different grout formulations of potentially 

varying hydraulic conductivity. 

Finally, NRC concludes that switching from Holcim Grade 100 to Lehigh Grade 120 slag is likely 

beneficial with respect to the chemical performance of grout placed in Tank 12H due to the 

higher activity index and reduction capacity. The compressive strength is also expected to 

increase due to a combination of small particle size and enhanced reactivity of the higher grade 

slag. Assuming grout performance and testing requirements are met, tank grout comprised in 

part of Grade 120 slag likely will meet PA assumptions and closure of Tank 12H and those to be 

closed in the future will likely be carried out in compliance with performance objectives.

Grout Segregation

Prior to the February 2–3, 2016, onsite observation visit, NRC staff reviewed a representative 

sample of the complete set of video footage that DOE provided of Tank 16H bulk tank and 

annulus grouting (SRR-CWDA-2015-00170). Grout less prone to bleed water segregation6

appeared to be placed near the active riser, probably due to locally high elevations associated 

with mounding. However, NRC consistently observed rapidly migrating dark water exuding (i.e., 

bleeding) from slowly flowing, light-colored grout lobes as they move away from the discharge 

zones of Tanks 18F, 19F, 5F, 6F, and now 16H. NRC note the potential for bleed water to 

segregate from the grout mix during grout flow and distribution throughout the tank, whereby 

potentially higher water to cement ratio grout is delivered to outlying portions of the tank far from 

the discharge riser. Dark water emerges from the free surfaces of freshly flowing light-colored 

grout lobes: from their front edges, side edges, and top surfaces. Numerous examples of 

bleed water segregation were documented by video cameras in the Tank 16H primary and in 

the annulus (SRR-CWDA-2015-00170). Camera operators watching a 42-in (107-cm) monitor 

in the command center (ADAMS Accession No. ML15239A612) seemed interested in this 

phenomenon based on cameras that focused in on such occurrences and on aqueous ponds

forming in low points at tank edges far from the active riser (SRR-CWDA-2015-00170). 

 

On both days 20 trucks were delivered totaling approximately 64,000 gallons of grout for Lift 1. Lift 1 was initiated 

utilizing grout made with Grade 100 slag and was switched to Grade 120 slag with the eighth truck delivered on 

January 20, 2016. Therefore, 27 trucks containing grout made with Grade 100 slag were placed in Tank 12H

resulting in approximately 43,00 gallons of grout made utilizing Grade 100 slag. Starting with the eighth truck on 

January 20, 2016, the remainder of the grouting was done utilizing Grade 120 slag. 6 The term “bleed water segregation” describes the movement of excess water to the surface of fresh grout (e.g., 

Wainwright and Ait-Aider, 1995; Olorunsago, 1998; Josserand et al., 2006). Bleeding is visual evidence of the 

gravitational settlement of heavy aggregate that comprises the granular skeleton of the grout matrix; the 

consolidation process displaces mix water upward and outward. Bleeding is observed when the bleed rate 

exceeds the evaporation rate, and the evaporation rate in the high-humidity in-tank environment is likely low. 

Bleeding is regulated by the particle size distribution of the cement(s) in the grout mix and, in particular, by the 

quantity and reactivity of the cement(s) (Wainwright and Ait-Aider, 1995). Excessive bleed water production, 

which has been observed by NRC in video of grouting operations conducted in Tanks 18F, 19F, 5F, 6F, and 16H, 

could result in significant in-tank heterogeneities (i.e., variable water-to-cementitious materials ratio, compressive 

strength, and hydraulic conductivity, among other factors). 
- 13 -

Based on these observations, NRC staff find that excess water was exuding from the bulk mass 

of flowing tank grout when it was being distributed throughout Tank 16H, and that this exudate

increased the overall volume of water that collected in pools at the tank wall beyond the amount 

introduced as slick line and tremie lubricant. Mounded grout will hydrate in a relatively dry 

microclimate, whereas grout submerged under standing water at the tank perimeter will hydrate 

in a saturated microclimate; because of this, grout properties are unlikely to be uniform (ADAMS 

Accession No. ML13127A291). Tank grout that hydrates and hardens in a subaqueous 

environment might be of different quality relative to that forming subaerially, although it is not 

entirely clear which environment will produce higher-quality, better-performing grout as 

discussed in more detail below.

When NRC staff reviewed portions of the Tank 5F and 6F grouting video with DOE staff during 

a March 26–27, 2014, onsite observation visit, DOE staff had said that water pooling in the tank 

was either chromated water from flushing of failed cooling coils or Slick Willie (Enviro-Systems, 

Smyrna, Georgia) aqueous pump-priming agent [i.e., a powder added in what amounts to 

9 cubic feet (0.25 cubic meters) of water to form a solution] (ADAMS Accession No. 

ML14342A784). During a teleconference on October 29, 2014, DOE quantified the total 

volumes of pump-priming solution added to Tanks 5F and 6F. According to DOE’s calculations, 

Tank 5F received approximately 1,050 gal (3,975 L) of aqueous Slick Willie over a 17 partialday grouting period, while Tank 6F received approximately 875 gal (3,312 L) over a 16 partialday grouting period; therefore the aqueous solution was added to the waste tanks at an average 

rate of ~60 gal/day (227 L/day) (ADAMS Accession No. ML14330A037; SRR-CWDA-2014-

00029). Slick Willie was added to Tanks 5F and 6F separately from the tank grout that was 

discharged into each tank, and the two substances were not actively mixed together. 

Data published by Enviro-Systems about the physical properties of cementitious materials that 

set up after being thoroughly mixed with Slick Willie are not directly relevant. Thus, NRC cannot 

rely on such information to support DOE’s conclusion that the aqueous Slick Willie solution was

incorporated into the grout monolith in a manner that would not negatively impact later 

percolation of water through the grout monolith (ADAMS Accession No. ML14342A784). Slick 

Willie was also previously disposed of inside Tanks 18F and 19F, according to DOE (ADAMS 

Accession No. ML16167A237). As a follow-up action to the May 17, 2016, teleconference, DOE 

agreed to provide an estimate of the total volume of Slick Willie added to Tanks 18F and 19F. 

In the Tank 5F and 6F lessons learned document (SRR-CWDA-2014-00015), Lesson #11 

stated that: “Near the end of bulk tank filling, liquid was observed near the bottom of a few 

risers.” DOE had prepared Work Order No. 01199254-65 specifically for such a case in order to 

remove excess liquid from risers near the end of grouting activities. At the March 26–27, 2014 

onsite observation visit, DOE stated, however, that this work order was unnecessary because 

there was no free water to be removed (ADAMS Accession No. ML14106A573). Ultimately, 

SRR-CWDA-2014-00015 recommended using less Slick Willie in the future [i.e., <60 gal/day 

(<227 L)] to minimize potential for unincorporated liquid to be encased in grout inside the tank. 

In response to that recommendation, DOE indicated that they would simply no longer dispose of 

Slick Willie in future tanks, beginning with Tank 16H (ADAMS Accession No. ML15239A612; 

ADAMS Accession No. ML14330A037). Slick Willie pump-priming agent, which is to remain in 

use at the grout pump, will instead be disposed of by other means (ADAMS Accession No. 

ML14342A784). During the July 28–29, 2015, onsite observation visit, DOE approximated that

from 5 to 7 gal (18.9 to 26.5 L) of water per day (quantity was dependent on the length of the 

line) was used to lubricate the Tank 16H slick lines and tremies at the beginning of the day and 

was then discharged into the primary. This occurred daily during 25 days of grouting, summing 
- 14 -

to a total of ~175 gal (~660 L) of water added to the primary (ADAMS Accession No. 

ML15239A612; ADAMS Accession No. ML16167A237). On this basis, approximately an order 

of magnitude less lubrication water was discharged into Tank 16H than had been discharged 

into each of Tanks 5F and 6F in the form of Slick Willie solution (ADAMS Accession No. 

ML16167A237). Likewise, it took 6 days to grout the annulus, so up to 42 gal (160 L) of 

lubrication water was discharged into it (ADAMS Accession No. ML16167A237). Re-lubrication 

of slick lines and tremies later in the day is not a typical occurrence (ADAMS Accession No. 

ML16167A237). NRC staff will continue to evaluate the sources of water that contributed to the 

development of significant ponds within low spots inside this and other tanks. DOE should 

continue to minimize or eliminate excess water introduction to waste tanks or provide additional 

support that the excess water does not negatively impact performance. For example, DOE 

could provide additional information on bleed water evaporation rates, and could provide 

additional information that excess water initially present or introduced to Tanks 18F, 19F, 5F, 

6F, 16H, and 12H did not reduce the integrity of the various grout monoliths to less than what is 

assumed in the PA. 

Grout Drop/Placement Testing

To date, DOE has delivered grout to the tanks using a Thom-Katt (TK) 70 pump, slick lines, and 

tremies7 located no greater than 5 ft (1.5 m) above the grout surface (see Figure 1). For 

example, Work Order Nos. 01199252-30 and 01199254-18 called for grout to be placed into 

Tanks 5F and 6F through multiple risers with a maximum drop height of 5 ft (1.5 m). DOE used 

<5-ft (<1.5 m) drop height to minimize bleed water segregation. During the March 26–27, 2014, 

onsite observation visit, DOE indicated that their grout team recommended additional testing 

take place before using a drop height >5-ft (>1.5 m) because the tank grout with higher slump 

placed into tanks with cooling coils had a greater potential for bleed water segregation (ADAMS 

Accession No. ML14342A784). The grout drop test report (RPT-5539-EG-0016), detailed in 

Appendix A, documented the results of three tests conducted to evaluate the potential for bleed 

water segregation to occur with increased drop height or due to the presence of aqueous pools. 

The results of three grout drop tests are summarized next, along with DOE’s related decisions.

During Test 1, grout was discharged by tremie into a dry mold from a drop height of 5 ft (1.5 m);

therefore, this grout drop test case was most similar to current tank grouting operations when 

and where aqueous pools are absent. A slight decrease in aggregate at the top of a sample 

taken from the 9 ft (2.7 m) radius position was observed in a sample removed from the monolith 

of Test 1 (RPT-5539-EG-0016, Page 44 and Figure 32, Sample T1-9-O-1). NRC review of the 

video of this grout drop test revealed what looked like poorly mixed aggregate rather than wellmixed grout initially discharging to the test pool, although this observation was not discussed in 

the report.

During Test 2, grout was discharged by tremie into a 4-in (10-cm) standing pool of water from 

a drop height of 5 ft (1.5 m) and at a relatively low discharge rate of 0.8 cubic yards (0.61 cubic 

meters) per minute. When grout is discharged from a tremie into a ponded aqueous 

environment, bleed water segregation may be further enhanced and exacerbated (cf. SRNL-

 7 A tremie is a long flexible pipe/hose that is inserted into the tank (through one of the tank risers) to guide the 

placement of the tank closure grout and limit the free fall of the grout (to less than five feet). When the grout level 

reaches the bottom of the tremie, the tremie is dropped into the tank and a new tremie is placed approximately 

five feet above the grout (or the maximum allowed free fall height).
- 15 -

STI-2012-546; SRNL-STI-2012-576). RPT-5539-EG-0016 described significant segregation of 

aggregate from fines, with aggregate remaining near the drop point and also stratifying at low 

levels due to gravitational effects, while fines and water were rapidly swept out to the tank 

perimeter (see Pages 20 and 44, Figure 33, Samples T2-5-O-1 and T2-9-O-1). The role that 

grout discharge rate has in bleed water segregation was not directly addressed by this test, but 

DOE contractors indicated that while higher discharge rates could lead to greater segregation, 

DOE did not think that the discharge rate would have a significant impact on the reported results

(ADAMS Accession No. ML16167A237). It is also important to note that DOE contractors

stated that the grout drop tests (RPT-5539-EG-0016) are not expected to be representative of 

real tank systems (ADAMS Accession No. ML16167A237)--placing grout into 4 in (10 cm) of 

pooled water is not typical of grouting operations at the tank farm facilities. DOE emphasized 

the different mixing energies that are associated with pouring grout directly into standing water 

versus that of the more typical grout flow lobes as they slide into standing water in low-lying 

areas of the tanks (ADAMS Accession No. ML16167A237). Likewise, the bench-scale saltstone 

studies of Cozzi and Pickenheim (SRNL-STI-2012-546; SRNL-STI-2012-576)8

, summarized in 

Appendix A, also do not mimic a typical tank grout discharge scenario in any way, and therefore 

those results are also not directly applicable to tank grouting operations for more reasons than 

grout formulation alone.

Figure 1. Grout Drop Test Molds with Boom Pumper Truck and Tremie (Photograph 

Adapted from RPT-5539-EG-0016).

 8 The Cozzi and Pickenheim studies were undertaken to better understand the potential impacts on 

physicochemical saltstone properties associated with the presence of excess water and indicate positive 

performance impacts of excess water. As discussed in the Appendix A summary of Cozzi and Pickenheim, DOE 

tested samples with a water to cement ratio of either 0.6 or 0.64. The water to cement ratios may not represent 

conditions in the field due to incorporation of excess flush water into saltstone.
- 16 -

Prior to commencing grouting operations in the Tank 12H primary, 3,500 gal (13,250 L) of water 

remaining in the tank was largely evaporated over the course of approximately 1 year, but 

residual pools present on the floor of the tank when grouting began were mapped and those 

areas were avoided during initial grouting of Tank 12H (ADAMS Accession No. ML16111B174). 

During the February 2016 onsite observation, NRC also noted that DOE had temporarily 

skipped grouting Lifts 2 and 3 in the Tank 12H annulus. DOE explained that the delay was due

to accumulation of water in the annulus from groundwater in-leakage. Based on Test 2 results, 

DOE indicated in their Tank 12H grout strategy document that they would avoid placing grout 

directly into wet areas of the tank because doing so could enhance bleed water segregation 

(SRR-LWE-2014-00147; ADAMS Accession No. ML16111B174). Similarly, Tank 16H video 

footage dated June 2, 2015, showed standing water in the primary before grouting operations 

commenced. During a recent teleconference, DOE indicated that sources of water in tanks and 

annuli prior to grouting may include Slick Willie pump priming agent, bleed water segregation, 

chromated cooling coil flush water, condensation associated with the ventilation system, and 

groundwater in-leakage (ADAMS Accession No. ML16167A237).

During Test 3B, grout was dropped in freefall from a height of 42 ft (12.8 m) into a dry mold. 

The discharge rate used during this test (1.27 cubic yards per minute) was consistent with 

rates of from 1.0 to 1.4 cubic yards per minute used during actual waste tank grouting under 

continuous discharge conditions. Bleed water segregation was not visually apparent in the 

samples collected from this monolith. For Test 3B, grout quality also appeared to be more 

homogeneous, perhaps due to grout being placed into the containment mold over a wider 

discharge zone via diffuse freefall. Based on these results, DOE prepared the Tank 12H grout 

strategy document to allow grout placement absent use of a tremie (SRR-LWE-2014-00147); 

however, DOE later confirmed that a tremie was used during Tank 12H grouting operations to 

control grout placement and minimize grout drop height (ADAMS Accession No. 

ML16167A237). Furthermore, DOE indicated it plans to continue using tremies during future 

grouting operations (ADAMS Accession No. ML16167A237).

RPT-5539-EG-0016 provides evidence that compressive strength and hydraulic conductivity are 

initially dependent on distance from the discharge zone, typically exhibiting higher quality 

properties near the impact point and lower quality properties further away (RPT-5539-EG-0016, 

see Figures 24–28, 30), although results for Tests 1 and 3B at later times showed an 

improvement in properties over time (e.g., RPT-5539-EG-0016, see Figures 30 and 31). NRC 

raised potential technical issues associated with excessive bleed water segregation in ADAMS 

Accession No. ML13127A291 that are supported by information presented in RPT-5539-EG0016, specifically, that “Grout matrix porosity and permeability may increase radially due to the 

shedding of segregated water to zones near [the] tank perimeter.” However, the performance 

impact of bleed water segregation of SRS tank grouts away from the discharge zone has yet to 

be determined, and studies conducted by Cozzi and Pickenheim (SRNL-STI-2012-546; SRNLSTI-2012-576) suggest some benefit of excess water with respect to grout performance, 

although the applicability of the test results to SRS tank grouting is unclear. 

Although grouting into pools of standing water is clearly not recommended for tank grouting, the 

potential differences in the physicochemical properties of reducing grouts associated with 

grouting in more modest amounts of standing bleed water versus exposure to dry air has also 

been studied by Cozzi and Pickenheim (SRNL-STI-2012-00546; SRNL-STI-2012-00576) albeit 

for different grout formulations then used in SRS tanks. For more information, see the reference 

summaries in Appendix A. During this study, saltstone grout specimens that were exposed to 
- 17 -

ambient air during hydration exhibited hydraulic conductivities that were three orders of 

magnitude greater than those of specimens hydrated in a high humidity environment, perhaps 

due to development of shrinkage microcracks. Moreover, and perhaps partly because of their 

relatively high hydraulic conductivities, specimens that became hydrated and potentially 

oxidized while exposed to ambient air exhibited the greatest tendency to leach incorporated 

constituents. For specimens hydrated in sealed, high-humidity containers, neither the water-topremix ratio nor excess standing water had appreciable effects on hydraulic conductivity 

magnitude and leachability. Saltstone grout specimens that were developed by pouring grout 

into 10 percent excess salt solution exhibited a 4 to 5 percent increase in density from top to 

bottom, due to enhanced bleed water segregation and settling in an environment containing 

excess water. Likewise, seven of eight samples tested exhibited density-dependent effects on 

hydraulic conductivity, but the effects were not significant enough to effect grout quality. 

Overall, this study demonstrated that premature drying of reducing grouts during early hydration 

is detrimental to their quality with respect to isolating waste. Therefore, maintaining a moist 

environment inside tanks and vaults is critical to development of high-quality grout properties, 

including the relatively low values of hydraulic conductivity assumed in the tank farm PAs.

As stated above, during the May 17, 2016 teleconference, DOE indicated that the results of the 

grout drop test report are not thought to be representative of grouting operations at the Tank 

Farm. Moreover, DOE indicated that while some bleed water segregation should be expected, 

the grout does not mix with the excess water and that the quality of the grout should not be 

considered lower quality (ADAMS Accession No. ML16167A237)9

. Nonetheless, NRC 

concludes that DOE has not ruled out the potential for a dependence of grout quality on 

distance from the drop point and that the presence of ponded water during grouting operations 

may serve to enhance the natural bleed water segregation that appears to be inherent to the 

tank grout mix10. Therefore, DOE should continue to make an effort to remove copious 

amounts of excess ponded water from waste tanks and annuli before and during grouting 

operations, whenever aqueous ponds are present, to increase the likelihood that higher-quality 

grout that meets the assumptions of the HTF and FTF PAs is placed into waste tanks and 

annuli. While it appears clear that aqueous ponds should be avoided, it is unclear what quantity 

of excess water will lead to undesirable grout properties. Thus, NRC will continue to monitor 

DOE grouting operations and evaluate testing designed to better understand the performance 

impact of excess water in SRS tanks during grouting.

With respect to use of Grade 120 slag, NRC expects that switching from coarser-grained 

Grade 100 slag cement to finer-grained Grade 120 slag cement may reduce bleed water

segregation (SCA, 2002; Topçu and Elgün, 2004) because Grade 120 slag is more reactive 

than Grade 100, and can thereby induce faster kinetics and more rapid hydration reactions 

(ADAMS Accession No. ML16167A237). Staff will continue to evaluate the extent of bleed 

 9 It is worth noting that Center for Nuclear Waste Regulatory Analysis (CNWRA) staff, who tested intermediatescale, reducing grout physical analog monoliths, observed permeability variations ranging over five to seven orders 

of magnitude due to the presence of cracks and shrinkage gaps (Dinwiddie et al., 2012; Table 4-1), whereas DOE 

maintains that they expect permeability of tank grout to vary over no more than one order of magnitude (ADAMS 

Accession No. ML16167A237). 10 Based on video observation of tank grouting (SRR-CWDA-2015-00170), bleed water segregation may be endemic 

to the tank grout mix (C-SPP-F-00055) (e.g., see earlier discussion and summary of Tank 18F video observations 

contained in ADAMS Accession No. ML13127A291).
- 18 -

water production in Tank 12H and other tanks to be grouted in the future to verify NRC 

expectations.

Grout Shrinkage

Grout expands during the heating process associated with hydration and then shrinks during 

cooling, leaving annular shrinkage gaps between the bulk grout mass and other paraphernalia 

inside tanks and tank annuli, including gaps at walls, around carbon steel cooling coils, 

equipment, and between adjacent grout flow lobes. Tank grout and clean cap grout are not 

shrinkage compensating grout mixes. DOE is not planning to develop a shrinkage 

compensating grout formula due to the low priority they place on this issue and inadequate 

funding levels (ADAMS Accession No. ML14342A784) and it deleted use of shrinkagecompensating admixtures from Revision 3 of the tank grout procurement specification (C-SPPF-00055). NRC staff view work to develop shrinkage-compensating grout formulas as 

potentially important to the adequate closure of tanks. The NRC staff concurs with 

Stefanko and Langton’s (2013) recommendations in SRNL-STI-2011-00551 for testing of 

shrinkage-compensating admixtures and implementation of measures to help mitigate tank 

grout shrinkage. DOE should consider giving higher priority to development of a shrinkage 

compensating grout formula and to its subsequent testing.

In SRNL-STI-2011-00551, Stefanko and Langton (2013) described how H.N. Guerrero designed 

instrumented shrinkage characterization test forms and a test protocol for measuring 

dimensional changes of the tank grout as a function of temperature, time, and relative humidity. 

These shrinkage tests were postponed by Tank Closure Project personnel, but DOE is now 

reengaged in performing ongoing ASTM C157 shrinkage testing of tank and clean cap grouts by 

testing both fully submerged (subaqueous) grout samples and fully subaerial grout samples 

hydrated in nearly 100 percent relative humidity conditions (ADAMS Accession No. 

ML16111B174; ADAMS Accession No. ML16167A237). The conditions under which some of 

the ASTM C157 shrinkage test(s) were performed may not be directly relevant to subaerially 

mounded tank grout hydrating inside waste tanks, yet others may be representative of 

conditions affecting grout that hydrates inside waste tanks beneath pools of excess water. 

Shrinkage of subaerial grout may increase significantly as relative humidity decreases below 

100 percent. The extent of shrinkage occurring inside waste tanks may be greater than implied 

by DOE’s shrinkage testing results due to tank ventilation ongoing during grouting operations 

that would reduce relative humidity by some unknown amount. DOE estimated that ventilation 

rates in the Tank 16H primary and annulus were 24,000 cubic feet per hour and 

11,000 cubic feet per hour, respectively, during grouting (ADAMS Accession No. 

ML16167A237). DOE is testing shrinkage of clean cap grouts prepared with two water-topremix ratios (0.45 and 0.5) and Grade 120 slag (the clean cap grout placed into Tank 16H was 

formulated with a water-to-premix ratio of 0.5 and Grade 100 slag) (ADAMS Accession No. 

ML16167A237). Therefore, the applicability of eventual test results is unclear. The shrinkage 

testing reports will not be completed until December 2016 (tank grout) and June 2017 (clean 

cap grout) at the earliest (ADAMS Accession No. ML16167A237).

If percolating water flow occurs primarily through cracks or gaps in the tank grout, it may come 

into contact with a much smaller fraction of the tank grout than it would if traveling through the 

matrix, leading to rapid, localized depletion of the reductive and buffering capacity of the tank 

grout along preferential fast flow paths. Because DOE assumes that the solubility of certain key 
- 19 -

radionuclides is dependent on the chemistry of the percolating water, with lower solubility 

expected for water adequately conditioned by its interaction with tank grout, the extent of 

interaction between percolating water and tank grout is risk-significant. NRC staff will continue 

to evaluate the potential for annular and shrinkage gaps to form around internal tank fixtures, at 

tank walls, and between individual grout flow lobes, which may lead to bypass of the reducing 

grout matrix in preference for faster flow pathways, resulting in less water conditioning.

The impact of bypassing flow through the tank grout is being studied by NRC’s contactors at the 

Center for Nuclear Waste Regulatory Analyses (CNWRA). CNWRA has performed water 

conditioning experiments using a synthetic SRS groundwater interacting with (i) an early 

generation reducing grout and (ii) tank grout prepared with Grade 100 slag cement (i.e., 

according to C-SPP-F-00055). Dynamic flow tests using early generation reducing grout 

specimens indicated that the pH of synthetic SRS groundwater increases to a value above 

10 pH units almost immediately after contacting the grout (Walter and Necsoiu, 2015). 

Static tests of nominally 0.06-in3 (1-cm3

) specimens of tank grout with a grout-to-water-mass 

ratio of 0.7 resulted in a steady Eh of −77 mV after 5 days with dissolved oxygen concentrations 

<8 ug/L. Two subsequent static tests using the same grout specimens resulted in steady Eh 

values of −10 to −20 mV after 3 to 4 days. Although the statistic tests attempted to maximize 

interaction between the grout and water through use of small cubes of tank grout, the low, initial 

Eh values of -470 mV assumed in DOE’s PA were not achieved in these tests. CNWRA staff 

more recently prepared tank grout specimens with Grade 120 slag cement and plans to test the 

grout prepared with the Grade 120 slag in future water conditioning experiments.

The distinction between slow matrix flow through reducing tank grout versus rapid bypass flow 

through shrinkage gaps and cracks is important to performance. NRC staff acknowledges the 

difference in impact to performance of distributed grout shrinkage within a Type I waste tank 

containing ~6.9 km (~4.3 mi) of cooling coils (SRR-CWDA-2010-00128) or a Type II waste tank 

containing ~9.0 km (~5.6 mi) of cooling coils (SRR-CWDA-2015-00159) and the potentially 

more focused grout shrinkage expected to occur in a tank without cooling coils. Shrinkage 

away from carbon steel cooling coils may serve to somewhat increase gap-localized interaction 

between groundwater and tank grout and result in greater water conditioning compared to a 

case where focused and larger-scale shrinkage away from the tank wall dominates all water 

flow as may be the case for Type IV tanks. If grout shrinkage were to occur around cooling coils 

as well as at grout flow lobe interfaces and monolith edges at the tank or annulus wall and at 

structural columns/equipment, infiltrating water could be directed through the interior of the tank

via many more distributed preferential pathways, potentially conditioning infiltrating water more 

than in the absence of cooling coil annular shrinkage gaps. Nevertheless, NRC staff expects 

DOE to provide information and test results sufficient to evaluate conceptual models reflecting 

preferential flow through tank grout monoliths, whether that flow occurs around the cooling coils, 

at the interface of individual grout flow lobes, along the length of large-scale, vertically oriented

equipment, or along tank and annulus walls, if preferential flow through such pathways cannot 

be ruled out.

Groundwater In-Leakage in Tank 12H

Groundwater in-leakage into SRS tank systems has been documented in tank inspection and 

other DOE reports. During the February 2016 onsite observation visit, NRC inquired about the 

delay in placement of Lifts 2 and 3 in the annulus of Tank 12H. DOE indicated that placement 

of these grout lifts was delayed due to the presence of approximately 6 in (15 cm) of 
- 20 -

groundwater that had accumulated in the annulus over a 5-day period (ADAMS Accession No. 

ML16111B174), beginning immediately after the temporary ventilation system, which forced 

unheated air through the annulus, was shut off (ADAMS Accession No. ML16167A237). 

Approximately 9 in (23 cm) of groundwater was present in the annulus during the onsite 

observation visit (ADAMS Accession No. ML16111B174). Observations indicated that 

groundwater accumulated faster in the annulus when air was “pulled” under negative pressure 

rather than “pushed” through the annulus using positive pressure (ADAMS Accession No. 

ML16167A237 and SRR-LWE-2015-00048). DOE estimated that ~1000 gal (3,785 L) of 

groundwater was pumped out of the Tank 12H annulus (ADAMS Accession No. 

ML16167A237). DOE staff indicated during the February onsite observation that they expected 

water levels in the annulus could be reduced to no more than 2 in (5 cm) by pumped removal. If 

there was 2 in (5 cm) of standing water left remaining in the annulus when grouting began, 

bleed water segregation likely would have been enhanced (cf. RPT-5539-EG-0016, Test 2), 

which may or may not have had significant adverse impacts on hydraulic conductivity of the tank 

grout (cf. SRNL-STI-2012-00576). DOE was also prepared to remove accumulated water from 

the annulus into decant totes after annulus grouting had begun. During the May 17, 2016, 

teleconference, NRC inquired whether DOE had placed constraints on grouting operations 

related to accumulation of water in the tanks. DOE indicated that it uses expert judgement

based on when grouting is performed (ADAMS Accession No. ML16167A237). DOE indicated 

that the water level in Tank 12H was measured using a steel tape. That is, workers dropped a 

measuring tape with a weight attached into the water, and used a camera to read the water 

level from the tape (ADAMS Accession No. ML16167A237)11. DOE also has data on pumped 

water volumes removed from Tank 12H. NRC staff will follow-up with DOE on the amount of 

groundwater in-leakage that was pumped out of the primary or from risers. DOE staff indicated 

that water was pumped out of every Tank 12H riser. Dehumidification with heating was 

employed in the tank primary (ADAMS Accession No. ML16167A237). During the May 17, 

2016, teleconference, DOE indicated that it is working with SC DHEC to enable original, 

operational ventilation systems to remain in place during future grouting operations (ADAMS 

Accession No. ML16167A237) to better manage excess moisture. 

DOE indicated that no water had accumulated in the Tank 16H annulus at the start of grouting. 

DOE indicated that water observed in the primary at the start of grouting was related to cooling 

coil flushing (ADAMS Accession No. ML16167A237). Unlike Tank 12H, only the bottom of Tank 

16H is typically located below the water table.

Follow-up Items on Tanks 5 and 6

During an October 29, 2014, teleconference between NRC and DOE, batch ticket #039403 

associated with a grout load placed into the Tank 6F primary on August 28, 2013, was 

discussed (see ADAMS Accession No. ML14342A784). At that time, a remark on the batch 

ticket suggested that this grout batch had been rejected, even while it had been placed into the 

tank in its entirety. However, SRR-CWDA-2016-00031 indicates that the grout batch 

represented by batch ticket #039403 was unremarkable and not rejected, and that the prior 

grout batch associated with ticket #039402 had been rejected after up to 4 cubic yards of 

out-of-specification grout had been discharged into the tank through Riser 5. A construction 

 11 During tank operations, probes monitor water levels inside the tank. During tank isolation, however, the probes 

are removed from service and a video camera is utilized to monitor water levels thereafter (ADAMS Accession No. 

ML16167A237). 
- 21 -

discipline engineer did not approve of the runny appearance of the grout observed in the hopper 

(ADAMS Accession No. ML16111B174), halted the discharge, and rejected the entire grout 

batch even though up to half of the batch had already been placed (SRR-CWDA-2016-00031). 

Grout batch ticket #039402 was recently provided for NRC review as Attachment 1 to 

SRR-CWDA-2016-00031. Informational “info” slump flow test results were not recorded on this 

batch ticket, and while the discharge start time was recorded, the discharge stop time and total 

time en route to discharge were not recorded. DOE confirmed that the construction discipline 

engineer monitored the grout added to a TK 70 trailer-mounted concrete pump to provide a 

qualitative check on the grout quality and had the ability to reject a batch at any time (ADAMS 

Accession No. ML14342A784). As recommended by NRC staff in the Tank 5F and 6F technical 

review report (ADAMS Accession No. ML14342A784), DOE further investigated the situation 

and clarified during a February 2–3, 2016, onsite observation visit that this rejected grout batch 

lacked its full measure of aggregate (ADAMS Accession No. ML16111B174), despite the batch 

ticket indicating otherwise. Argos, the batch plant operator, and its personnel who observe 

preparation of each grout batch, were unable to identify a problem with the computer system 

used to batch the tank grout ingredients in their specified quantities (ADAMS Accession No. 

ML16111B174). DOE was unaware of similar problems occurring at the Argos batch plant 

previously, or of any similarly out-of-specification grout discharged into waste tanks during prior 

grouting operations (ADAMS Accession No. ML16111B174). In partial response to Action Item 

5 resulting from the July 2015 onsite observation visit (SRR-CWDA-2015-00170), DOE 

determined that no changes in procedure were needed because the construction discipline 

engineer’s quality control check had worked as intended. Based on this event, DOE has 

provided additional training to workers regarding conditions to watch for during the visual 

quality control check (ADAMS Accession No. ML16111B174). 

Finally, NRC staff previously addressed a non-conformance whereby all grout placed into

Tank 6F on September 19, 2013, contained excess water of approximately 2 to 3 percent

[i.e., 1–2 gal (3.8–7.6 L) per cubic yard more than specified by C-SPP-F-00055, Attachment 5.5] 

(ADAMS Accession No. ML14342A784). Recent review of associated video footage indicated 

that this grout was placed in the tank via Riser 5 (SRR-CWDA-2014-00029). A total of 25 to 30 

truckloads of relatively high water content grout was placed through a single riser over the 

course of a day. There is a potential for a higher permeability zone associated with a larger

water-to-cementitious materials ratio to have formed in this area that may increase flow at this 

location relative to other areas. NRC staff concludes that DOE’s procedures may not prevent 

significant quantities of lower quality grout from being discharged into waste tanks of visual cues 

are too subtle to observe a difference in grout properties, as was the case when a day’s worth of 

grout with excess water was placed in Tank 6F. However, the procedure may identify grout that 

is grossly out of specification, if that grout is observed to behave or appear significantly different 

than other truckloads of grout discharged to the tanks or annuli as was the case when a partial 

truckload of grout with insufficient aggregate was placed in Tank 6F. 

Alkali–Silica Reactivity

Alkali–Silica Reaction (ASR) is a slow process whereby the siloxane groups in siliceous 

minerals in the coarse aggregate (e.g., granite pea gravel in tank grout) are attacked by 

hydroxyl ions in highly alkaline pore solutions, resulting in formation of an alkali–silica gel 

(ADAMS Accession No. ML112241029; Qu et al., 2015; Sadek et al., 2016). Alkali–silica gel 

increases in volume (swells) with water imbibition and causes expansion, which may result in 

spalling, cracking and deterioration of stiffness and strength (Qu et al., 2015; Sadek et al., 
- 22 -

2016). Reactive siliceous minerals include chert, quartzite, opal, and strained quartz crystals

(ADAMS Accession No. ML112241029).

At the 28th Regulatory Information Conference, new research programs on “Alkali–Silica 

Reaction Degradation in Nuclear Concrete Structures,” being executed by (i) the National 

Institute of Standards and Technology (NIST; Sadek et al., 2016), (ii) Electric Power Research 

Institute (EPRI) and DOE (Qu et al., 2015; Guimaraes et al., 2016; Sellier et al., 2016; 

ORNL/LTR-2015/407), (iii) Institute for Radiological Protection and Nuclear Safety (IRSN; 

Marquié, 2016), and (iv) Organisation for Economic Co-operation and Development (OECD)

and the Nuclear Energy Agency’s (NEA) Committee on the Safety of Nuclear Installations 

(CSNI; Orbovic, 2016), were described. Many standard tests for ASR susceptibility are of 

limited use for common, moderately reactive aggregates (Guimaraes et al., 2016). There are no 

non-destructive evaluation tests that can reliably (i) identify ASR or (ii) determine the extent of 

ASR in a structure (Qu, 2015), but EPRI has developed six large-scale specimens that exhibit 

varying degrees of ASR for use in development of non-destructive evaluation methods 

(Guimaraes et al., 2016), and IRSN has just begun a 10-year effort in this arena (Marquié, 

2016). Development of ultrasonic and acoustic emission12 non-destructive evaluation methods 

are underway (Qu et al., 2015; Guimaraes et al., 2016; Marquié, 2016). NIST is developing 

strategies for identifying and quantifying reactive phases in aggregates (Sadek et al., 2016). 

Related ASR research, including numerical process modeling of the evolution of degradation 

and structural response (e.g., Sellier et al., 2016), is ramping up, but there were few results to 

report, with the exception of those obtained by Qu et al. (2015). ASR degradation numerical 

modeling workshops to analyze and interpret preliminary and final results are anticipated in 

2016 and 2017 (Sellier et al., 2016).

In the technical review report concerning Tank 18F and 19F grouting operations (ADAMS 

Accession No. ML13269A365), NRC staff evaluated tests that DOE conducted for ASR

susceptibility. NRC staff is concerned that DOE’s criterion for acceptance of vendor-supplied 

granite aggregate relies on short-term tests (ASTM C1260) that are unlikely (i) to predict ASR 

susceptibility over the long performance period and (ii) to demonstrate compliance with the 

performance objective specified at 10 CFR 61.41. NRC staff continues to recommend that 

DOE consider conducting tests to evaluate the potential for ASR degradation to occur to 

tank grout, given anticipated water ingress and environmental conditions (i.e., temperature and 

humidity variations), pore water alkalinity, and reactive aggregate volume fraction, and the 

potential effects of ASR on long-term performance of the engineered barrier system. Staff will 

continue to evaluate this technical issue during future monitoring activities.

Thermal Data Evaluation

During a teleconference on October 29, 2014, the NRC requested from DOE any available 

information regarding adiabatic temperature rise in tank grout (ADAMS Accession No. 

ML14330A037). DOE stated that they may instrument one or more tanks with thermocouples 

prior to grouting activities to obtain field-relevant temperature data (ADAMS Accession No. 

ML14330A037). DOE also indicated that the thermal data collected during the Tank 18F and 

19F Grout Scale-Up Test indicate that the semi-adiabatic temperature rise was 23 °C (41 °F), 

 12 Attachment 2 contains information on work commissioned by NRC at the Southwest Research Institute on the 

feasibility of use of acoustic emission monitoring to better understand the potential for and extent of crack 

formation in large, underground grout monoliths used for waste isolation at Savannah River Site.
- 23 -

which met the thermal objective for grout that can be mass placed (SRNL-STI-2011-00749). 

However, as stated in a NRC staff technical review report for Tanks 18F and 19F grouting 

operations (ADAMS Accession No. ML13269A365), it is not clear that the temperature profile 

and evolution measured in the test form are representative of temperatures and temperature 

gradients that would be attained during grouting of large waste tanks. NRC staff notes that 

environmental monitoring of hydrating tank grout, particularly in regard to its thermal evolution, 

would yield valuable data that is relevant to grout porosity, hydration products, and the potential 

for thermal cracking to occur within the various tank types. During the July 28–29, 2015, onsite 

observation visit, however, DOE informed NRC staff that it had no plans to install thermocouple 

strings or similar sensors in a waste tank to measure spatiotemporal temperature variations and 

gradients attained during grout hydration (ADAMS Accession No. ML15239A612). 

NRC’s recommendations concerning thermal characteristics of the tank grout remain the same 

as those for Tanks 18F, 19F, 5F, and 6F. Specifically, DOE should:

• Conduct a more detailed thermal analysis that considers tank-specific grout pouring 

sequences and geometries to determine the potential for thermal cracking of the tank 

grout.

• Measure the adiabatic temperature rise and thermal properties of the grout once placed 

in the tank, because temperatures/temperature gradients attained may influence 

porosity, hydration products, and the potential for thermal cracking.

NRC staff will continue to evaluate this technical issue during future monitoring activities.

Annulus and Ventilation Duct Grouting

The East and West risers were used to grout the Tank 16H annulus. For improved visibility of 

annulus grouting operations, the NRC staff previously recommended that DOE consider placing 

video cameras in all tank annuli risers, if available, or else occasionally reposition cameras 

during grouting operations if cameras could not be placed in all available risers simultaneously 

(ADAMS Accession No. ML14342A784). However, video cameras were located only in the 

East and West Risers of Tank 16H, in contrast to the strategy employed during Tank 5F and 6F 

annulus grouting when cameras were only installed in the North and South Risers, 

approximately 90 degrees from the nearest discharge riser in Tank 5F and 6F (the East and 

West Risers were used to place grout in Tank 5F and 6F). During a March 26–27, 2014, onsite 

observation visit, DOE indicated that the visibility of the Tank 5F and 6F annuli was 

approximately 50 percent (ADAMS Accession No. ML14342A784); visibility of the Tank 16H 

annulus likely was similar. During the February 2–3, 2016, onsite observation visit, DOE stated 

that Tank 12H annulus cameras were located in the East and West Risers and one may be 

placed in the South Riser, but that none could be placed in the North Riser (ADAMS Accession 

No. ML16111B174).

The Tank 16H and 12H closure modules (SRR-CWDA-2013-00091 and SRR-CWDA-2014-

00086) suggested that grouting the annulus ventilation duct might require a grout more 

flowable than tank grout; however, neither grout strategy document (SRR-LWE-2014-00013 or 

SRR-LWE-2014-00147) addressed the issue. Later, DOE reiterated the potential use of a more 

flowable, but otherwise undefined grout during the February 2–3, 2016, onsite observation visit 

(ADAMS Accession No. ML16111B174). During a recent teleconference, however, DOE 
- 24 -

indicated that only tank grout was used to fill the Tank 16H duct, including its vertical section 

(ADAMS Accession No. ML16167A237).

During the July 28–29, 2015, onsite observation visit, DOE staff described Tank 16H annulus 

grouting operations of the 12-to-18 in (31-to-46 cm)-diameter horizontal ventilation duct, the top 

of which is 18 in (46 cm) above the annulus floor (ADAMS Accession No. ML15239A612; SRRCWDA-2013-00091, Figure 7.3-3; ADAMS Accession No. ML16167A237). The diameter of the 

horizontal ductwork tapers from 18 in (46 cm) at its junction with the vertical inlet and exhaust 

ductwork to 12 in (31 cm) on the opposite side of the annulus (ADAMS Accession No. 

ML16167A237; Tank 16H Ventilation Diagram W163389). In contrast to structural-support–

related grouting procedures used when grouting Tanks 5F, 6F, and 12H, pre-grouting of the 

Tank 16H annulus pan to the base of the smallest horizontal duct, where it is at most 6 in (15 

cm) above the pan, was not undertaken. Also in contrast, the horizontal ductwork was filled on 

June 11, 2015, with grout via open registers during bulk filling operations, and direct filling of the 

horizontal ductwork through its vertical inlet and exhaust ventilation ports was not performed 

(ADAMS Accession No. ML15239A612; SRR-CWDA-2015-00095). DOE noted that the

degraded condition of the Tank 16H ductwork, including broken, open seams, rust holes, and 

punched holes from removal of sample coupons, led to the decision to grout it from the outside,

using its 16 rectangular registers, sized 14 in by 6 in (36 cm by 15 cm) and spaced 17 ft (5 m) 

apart, as well as other failure-point openings to deliver grout into the duct from both above and 

below (ADAMS Accession No. ML16167A237). A 10-to-15-ft (3.0-to-4.6-m) arc length of the 

annulus contained no horizontal duct (ADAMS Accession No. ML16167A237). From the 

vantage point of the two cameras that viewed the annulus, there were 8 or 9 registers that could 

not be observed (ADAMS Accession No. ML16167A237). During the May 17, 2016, 

teleconference, DOE indicated that if the horizontal ductwork is substantially intact, they will 

always fill waste tank ventilation ducts from inside via the vertical inlet and exhaust ducts as 

grout entry points (ADAMS Accession No. ML16167A237); such was not the case for Tank 16H.

Also during the July 28–29, 2015, onsite observation visit, DOE indicated that residual waste in 

the Tank 16H ductwork (e.g., U-ESR-H-00113, Attachment 25—Tank Annulus Waste Heights) 

could block the flow of grout into the duct (ADAMS Accession No. ML16111B174). DOE 

visually confirmed entry of grout into some registers in the field of view of the East Riser 

camera, but could not evaluate volumetric grout uptake by the duct because its volume was 

negligible compared to that of the bulk annulus fill (ADAMS Accession No. ML15239A612; 

ADAMS Accession No. ML16167A237). DOE provided NRC with video acquired on June 11, 

2015, of initial grout inflow into the ventilation duct (SRR-CWDA-2015-00170), but no video was 

available from the West Riser camera during initial grouting operations due to the inopportune 

direction the camera was pointed when grout began flowing into nearby registers. The 

continuity of grout placement is particularly important when contaminated ducts are being filled. 

Uninterrupted flow of grout is essential to ensure that permanent porosity does not develop 

inside ductwork. Attachment 1 provides a description of NRC staff observations of the Tank 

16H horizontal ductwork grouting process. During the May 17, 2016, teleconference, NRC 

asked DOE to provide additional supporting information to justify its confidence that the 

horizontal ventilation duct in Tank 16H had been filled. DOE indicated that the large number of 

openings in the duct (see Tank 16H Ventilation Diagram W163389) and the direct video 

observations in the Command Center of grout entering some of the registers in the duct were 

sufficient justification to provide confidence that the duct had been completely filled on June 11, 

2015 (ADAMS Accession No. ML16167A237). While DOE’s approach to verifying placement of 

grout in the ventilation duct is reasonable, DOE should attempt to place and position cameras in 
- 25 -

such a manner to maximize visualization of grout entry and exit from duct registers. Improved 

visualization will increase the evidentiary support for void volume in the ventilation ducts having 

been filled and will enhance DOE’s ability to develop lessons learned related to grout placement 

strategies that will increase the likelihood that ducts are fully grouted and do not contain 

risk-significant void space.

With one exception, all tanks grouted to date had their vertical inlet and exhaust sections of their 

ventilation ducts filled nearly simultaneously with the placement of grout in the annuli outside 

each duct to ensure that structural integrity of each duct was maintained. For Tank 16H, 

however, DOE did not exercise the same abundance of caution. The Tank 16H procedure 

simply assumed that there was no danger of the duct being crushed by pressure applied by the 

external grout fill in the annulus (ADAMS Accession No. ML16167A237). When questioned, 

DOE indicated that staff observed no evidence of duct collapse in Tank 16H, yet DOE indicated 

that it returned to the typical, cautious grouting approach for alternating between grouting the 

annulus and the vertical duct in Tank 12H (ADAMS Accession No. ML16167A237). 

During the July 28–29, 2015, onsite observation tour, NRC staff noted discoloration in the 

annulus grout, or mottling that may have indicated bleed water segregation (e.g., Figure 2). 

The camera operator indicated that there were shadows around the edges of flow lobes, but not 

necessarily cracks; however, he noted that surficial microcracks were sometimes observed on 

the grout surface (ADAMS Accession No. ML15239A612). During review of Tank 16H annulusinspection video acquired on the mornings of June 15 and 16, 2015 (SRR-CWDA-2015-00170), 

NRC staff noted the presence of large-aperture cracks in grout that had been placed beneath 

the West Riser on June 11, 2015. During the inspections, camera operators seemed interested 

in viewing the wide-aperture cracks. Many were oriented radially (Figure 3), but one system of 

cracks was en echelon parallel to the inner wall and then rotated to radial (Figure 3B). Cracks 

were noted on either side of a tremie that had been dropped onto the grout surface on 

June 11, 2015 (Figure 3A and 3B). Another crack was located beneath and to the side of a pig 

released on June 11, 2015 (Figure 3C and 3D). During the May 17, 2016, teleconference, DOE 

indicated that more cracks were observed later, at higher levels in the annulus near the top of 

the tank, which they attributed to ventilation-induced drying (ADAMS Accession No. 

ML16167A237). DOE staff indicated that cracks were observed to have developed beneath 

pour points approximately six times during grouting operations, which they attributed to 

differential topography associated with mounding. Cracks were also observed in grout in the 

primary, which DOE attributed to drying (ADAMS Accession No. ML16167A237). 
- 26 -

Figure 2. A and B. Onlapping Black Bleed Water and Tank Grout Flowing Beneath. 

Date of Video: June 11, 2016. C. and D. Mottling Evidence of Black Bleed Water after 

Tank Grout Dried. Date of Video: June 15, 2016.

Figure 3. Cracks Formed in Tank Grout in the Tank 16H Annulus Beneath the West Riser. 

A. Cracks Formed North of the Discarded Tremie. B. En Echelon Cracks Formed South 

of the Discarded Tremie. C. Crack Formed Beneath Discarded Pig Further South of the 

Discarded Tremie. D. Jet Dropped Above Crack at Pig. Date of Video: June 16, 2016.
- 27 -

During the February 2–3, 2016, onsite observation visit, DOE noted that placement of Lifts 2 

and 3 in the Tank 12H annulus had been delayed due to the presence of accumulated 

groundwater in the annulus. While DOE pumped out the majority of standing water and waited 

for the remainder to evaporate, Tank 12H grouting proceeded directly from placement of Lift 1 to 

Lift 4 in the primary (ADAMS Accession No. ML16111B174).

The NRC staff will continue to evaluate technical issues associated with grouting the annuli,

ventilation ducts, and annulus risers of waste tanks during future monitoring activities.

Equipment Grouting

SRNL-STI-2011-00592 provides the grout formulation (T1A-62.5FA) used to grout equipment 

remaining in Tanks 16H and 12H. The equipment grout formulation called for use of Grade 100 

ground granulated blast furnace slag cement, but DOE planned to use Grade 120 to grout Tank 

12H equipment13. DOE indicates that there are no regulatory requirements for the properties of 

equipment fill grout, so there are no quality control test requirements associated with production 

of this grout (SRR-LWE-2014-000150 and SRR-LWE-2015-00032). The equipment fill grout is

mixed by SRR Construction and work is controlled via work package (SRR-LWE-2014-000150

and SRR-LWE-2015-00032). During the February 2–3, 2016, onsite observation visit, DOE 

staff described equipment grouting operations (ADAMS Accession No. ML16111B174; see also 

SRR-CWDA-2015-00095). Equipment grout was prepared onsite in small batches. SRR

personnel measured the dry ingredients by weight, pre-mixed them, and then combined the 

premix with water per the formulation. The mixture was allowed to hydrate using a low shear 

mixer, and then a high shear mixer was engaged to finish mixing the equipment grout and thin 

it, after which there was a short timespan before it would begin to set up. Equipment grout was 

metered as it was placed into small openings in each piece of equipment using gravity driven 

flow through a hose and funnel. Tank equipment had high point vents that collected overflow

and indicated that equipment filling was complete (SRR-LWE-2014-00013). The volume of 

grout accepted by each piece of equipment was recorded. During the July 28–29, 2015, onsite 

observation visit, DOE indicated that the mounded tank grout placed into Tank 16H was only 

1 to 2 ft (0.3 to 0.6m) from the top of the tank, and that contractors had begun to perform 

equipment grouting, which began on July 28, 2015, and was completed on July 30, 2015. 

In particular, DOE indicated that inspection ports 42 and 59 were being grouted during the visit 

and tour (ADAMS Accession No. ML15239A612).

While the equipment grouting tests performed by DOE focused primarily on the Advanced 

Design Mixer Pump (ADMP), these tests are also relevant to grouting equipment in Tanks 16H 

and 12H. The ADMP represents a bounding case for grouting internal tank fixtures because of 

its large size and complex flow path. Tank 16H has similar equipment, including a transfer jet, 

and a transfer pump (SRR-LWE-2014-00013). In the technical review report concerning Tank 

18F and 19F grouting operations (ADAMS Accession No. ML13269A365), staff expressed 

concern that the ADMP mock-up test described in SRNL-STI-2011-00564 provided insufficient 

data to support a conclusion that the ADMP void spaces could be completely filled with the 

tested equipment grouts to eliminate a potential vertical flow path through Tank 18F. However, 

the scaled-up version of this mock-up test (SRR-CES-2012-00031) provided sufficient data to 

 13 NRC has not yet reviewed documentation to confirm that Grade 120 slag was used to grout the Tank 12H 

equipment.
- 28 -

support that conclusion because equipment grout flowability was shown to be maintained for the 

required time and the test showed that the equipment grout could fill and vent through the same 

1-in (2.5-cm) diameter opening, successfully filling the mock-up equipment.

The Tank 16H final configuration report (SRR-CWDA-2015-00159) stated that the largest pieces 

of equipment in the tank (two rotary jet assemblies and a transfer pump) were filled with 

80 percent of the estimated grout volume to 20 percent more than the estimated grout volume. 

The NRC staff will continue to monitor equipment grouting, equipment grout shrinkage, and 

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

Cooling Coil Flushing and Grouting

Tanks 16H and 12H have 44 and 36 chromate water, carbon steel, 2-in (5-cm)-diameter cooling 

coils, respectively, inside their primary tanks (SRR-CWDA-2013-00091; SRR-LWE-2014-00147; 

SRR-CWDA-2015-00159). In Tank 16H, five coils that exhibited guillotine failure were flushed 

during cleaning, prior to grouting operations. Failed cooling coils were grouted after a 2-ft 

(0.6-m) layer of grout was placed in the primary to provide structural support (ADAMS 

Accession No. ML16167A237). This external level of tank grout was the minimum needed to

provide support to vertical coils while maximizing the potential for guillotined or severed coils to 

vent during grouting (SRR-LWE-2014-00013; SRR-LWE-2014-00147). For Tank 16H, failed 

coil grouting occurred on June 10, 2015, after bulk fill had been placed in the primary over a 

three-day period (SRR-CWDA-2015-00170, Attachment 1). Failed coils were grouted from each 

inlet and outlet. Details about failed coil grouting operations for Tank 12H will be available for 

review in the Tank 12H Final Configuration report, when it is complete.

For intact cooling coils, triple rinsing of coils as part of tank closure was recommended in the 

Tanks 5F and 6F grouting lessons learned document (SRR-CWDA-2014-00015). However, the 

practice and recommendation were abandoned for Tanks 16H and 12H as DOE thought a 

single water flush was sufficient (ADAMS Accession No. ML16167A237). For Tanks 16H and 

12H, intact cooling coils were flushed once in advance to remove chromate water before 

grouting operations began and again in conjunction with grouting the coils to minimize air 

entrainment (ADAMS Accession No. ML16167A237).

WSRC-STI-2008-00172 provides the cooling coil grout formulation (90 wt% Masterflow 816 

and 10 wt% Grade 100 ground granulated blast furnace slag cement) used to grout cooling 

coils in Tank 16H. Masterflow 816 is marketed by BASF Corporation as a cement-based,

aggregate-free, fluid, non-shrink, non-bleeding, high-strength cable grout with extended working 

time. For Tank 12H, DOE planned to use Grade 120 slag in place of Grade 100 slag to produce 

the cooling coil grout14. There are no requirements for the properties of cooling coil grout, so 

there were no quality control or test requirements associated with its production (SRR-LWE2014-000150 and SRR-LWE-2015-00032). WSRC-STI-2008-00172 indicates that the cooling 

coil grout is required to have a reductive capacity at least as great as the tank grout, if not 

greater. Because the cooling coil grout formulation was selected before the formulation for tank 

grout, NRC staff verified that tank grout had a weight percent (wt%) of blast furnace slag cement 

(i.e., 6 wt%) that is less than that of cooling coil grout (7.5 wt%) (SRNL-STI-2011-00551).

 14 NRC has not yet reviewed documentation confirming that Grade 120 slag was used to grout the Tank 12H 

cooling coils.
- 29 -

During the July 28–29, 2015 and February 2–3, 2016, onsite observation visits, DOE staff 

described Tank 16H and 12H cooling coil grouting operations (SRR-CWDA-2015-00095 and 

ADAMS Accession No. ML16111B174). WSRC-STI-2008-00298 recommended that DOE 

employ a mixing system that could blend the quantity of material required to fill one or more 

cooling coils. The total volumes of cooling coils range from 75 to 116 gal (284 to 439 L) 

(ADAMS Accession No. ML16111B174; SRR-CWDA-2015-00159). Therefore, 150 gal (568 L) 

batches of cooling coil grout (C-SPP-F-00057) were prepared. Cooling coil grout was mixed 

and placed by SRR Construction and controlled via work package (SRR-LWE-2014-000150 and 

SRR-LWE-2015-00032). Dry ingredients were premixed at a vendor facility and delivered to the 

site in a Super Sack® (BAG Corp, Richardson, Texas) (ADAMS Accession No. ML15239A612). 

SRR personnel then batched a fixed amount of water with the contents of the Super Sack and 

mixed it in a skid-mounted grout mixer. A hand pump was used to control pressure and flow to 

meter the grout into the cooling coils (ADAMS Accession No. ML15239A612). A totalizer at the 

flow meter provided the quantity of grout added to the coils in real time. WSRC-STI-2008-

00298 called for filling intact cooling coils with water prior to grout placement to remove air, 

prevent air entrainment, and help ensure that a liquid-to-liquid interface is maintained during 

cooling coil grouting. Intact cooling coils were thus reflushed with water (disposed of in another 

waste tank) and then grouted from the coil inlet. When a solid stream of grout was visually 

detected at the coil outlet, a minimum surplus of 10 gal (38 L) of grout was introduced to the coil 

to ensure complete filling (ADAMS Accession No. ML15239A612; SRR-CWDA-2015-00159). 

DOE confirmed that the water-to-grout interface was maintained throughout the process of 

grouting Tank 16H cooling coils. The flushwater/grout interface volume was collected at the 

outlet in totes, solidified, and disposed of separately (ADAMS Accession No. ML15239A612;

SRR-CWDA-2015-00159).

WSRC-STI-2008-00298 demonstrated that internally grouted piping surrounded by an insulating 

material underwent significant temperature rise during hydration. During the March 26–27, 

2014, onsite observation visit, NRC staff asked DOE how it controlled the temperature of 

cooling coil grout (ADAMS Accession No. ML14106A573). NRC staff also raised the issue of 

the potential for cooling coil grout to boil during hydration due to the insulation provided by 

external tank grout in the previous technical review report on grouting operations (ADAMS 

Accession No. ML14342A784). During the July 28–29, 2015, onsite observation visit, DOE 

indicated that the mounded tank grout placed into Tank 16H was at that time only 1 to 2 ft (0.3 

to 0.6 m) from the top of the tank (the primary was 94 percent complete), and that contractors 

were only then preparing to perform equipment and cooling coil grouting (ADAMS Accession 

No. ML15239A612). Thus, intact cooling coils were almost entirely encased in tank grout prior 

to being internally grouted with coil grout during the period from August 13–28, 2015 (SRRCWDA-2015-00170, Attachment 1). At the May 17, 2016, teleconference, NRC expressed 

concern with the timing of intact cooling coil grouting, which was performed only after the 

primary had been nearly filled, because of the potential for coil grout to boil when insulated by 

external tank grout. DOE indicated that workers, who routinely perform jobs in valve houses

related to installation, removal, and maintenance of grout hoses, have not observed high

temperatures that would suggest excessive temperatures in the coils (ADAMS Accession No. 

ML16167A237). Workers who have monitored sensors that would indicate excessive heat 

production have seen no evidence of such when disconnecting hoses (ADAMS Accession No. 

ML16167A237). DOE should continue to consider heat transfer requirements such that cooling 

coil grout does not exceed its boiling temperature after placement into a highly insulated system 

that is also producing its own heat of hydration (WSRC-STI-2008-00298).
- 30 -

Following unsuccessful grouting of five intact cooling coils in Tanks 5F and 6F, DOE 

subsequently implemented changes to the coil grouting process (e.g., addition of screens to 

capture debris and use of a larger diameter line-cleaning device) to improve the chances of 

success during future grouting operations (ADAMS Accession No. ML14342A784). During the 

February 2–3, 2016, onsite observation visit and the May 17, 2016, teleconference, DOE 

discussed the results of Tank 16H cooling coil grouting (ADAMS Accession No. 

ML16111B174and ADAMS Accession No. ML16167A237). Tank 16H had five cooling coils that 

exhibited guillotine failure, and each was successfully grouted from inlet and outlet. DOE 

indicated that one of these coils was fractured low (ADAMS Accession No. ML15239A612), 

suggesting that its outlet may have been encased in the stabilizing grout layer when it was 

grouted, and thus obscured. One failed (considered failed due to blockage) coil (Cooling Coil 

12) was grouted from both the inlet and outlet and altogether took only 11 gal15 (42 L) of grout 

(SRR-CWDA-2015-00159). Out of 39 intact cooling coils, DOE successfully grouted 37. Two 

other intact coils were not completely filled due to grouting delays that allowed some grout to 

harden inside the coils before they were completely filled (SRR-LWE-2015-00085). Cooling Coil 

17 took 81 of 116 gal (307 of 439 L), so it was approximately 70 percent filled (SRR-CWDA2015-00159). Cooling Coil 22 took 35 to 40 of 113 gal (132 to 151 of 428 L), so it was 

approximately 31 to 35 percent filled (SRR-CWDA-2015-00159). Likewise, details concerning

Tank 12H cooling coil grouting will be available for review in the Tank 12H Final Configuration 

report when it is complete. NRC staff reviewed the reasons why grouting of three cooling coils 

in Tank 16H was unsuccessful, and will continue to monitor the steps that DOE takes in the 

future to prevent in-process grouting delays that enables premature hardening of grout in coils 

before they are fully filled. DOE should consider making a backup grout addition line readily 

available that can be used if needed. NRC staff will continue to monitor DOE’s actions to 

prevent plugging of the cooling coil grout addition line.

Recommendations in the Tanks 5F and 6F lessons learned document (SRR-CWDA-2014-

00015) that may reduce radiation doses to workers associated with the flushing and grouting of 

cooling coils included (i) minimization of the time between coil flushing and subsequent grouting

operations, and (ii) planning ahead for high radiation/contamination potential by establishing 

temporary shielding and additional contamination controls. During the May 17, 2016, 

teleconference, DOE also indicated that for worker protection, it would be best to flush coils just 

once, immediately prior to grouting (ADAMS Accession No. ML16167A237).

NRC staff will continue to monitor cooling coil grouting, cooling coil grout shrinkage, how DOE 

minimizes air entrainment and controls the temperature of freshly placed grout under locally 

insulated conditions, and any future testing of the cooling coil grout formulation and operations 

that is undertaken.

Final Configuration

The final configuration of Tank 16H and deviations from the closure module (SRR-CWDA2013-00091), are described in SRR-CWDA-2015-00159, but uncertainties exist in the fill 

volumes reported. The actual reducing grout volume placed was within 97.7 percent of the 

estimate for Tank 16H. The volume of reducing grout placed in the annulus of Tank 16H was 

1.5 percent greater than anticipated, while the volume of tank grout placed into the tank and 

 15 As a point of reference, the internal volume of the cooling coils is approximately 75 to 116 gallons (ADAMS 

Accession No. ML15239A612); SRR-CWDA-2015-00159.
- 31 -

annulus risers were 9 percent greater than anticipated. In the final configuration report, DOE 

indicated that the actual reducing grout volumes reported were based on the total number of 

grout batches (i.e., truckloads) discharged into the tank and annulus, assuming 8 cubic yards 

(6.1 cubic meters) per load of tank grout and 7 cubic yards (5.4 cubic meters) per load of clean 

cap grout (SRR-CWDA-2015-00159). Because DOE does not take into account the exact 

amount of each tank grout batch that is used for testing, the volume estimates are uncertain. 

DOE previously stated that riser volume estimates should not be considered highly accurate 

because these estimates are based on the total time it takes to completely discharge one 

truckload of tank grout and the time it takes to fill a riser (ADAMS Accession No. 

ML14106A573). With regard to equipment grouting, the final configuration report provides 

comparison of the theoretical fill volume and the actual volume of buckets used to deliver the

equipment grout. ASTM C39 compressive strength testing indicated that the strength of 

the emplaced tank grout exceeds the compressive strength assumed in the HTF PA 

(SRR-CWDA-2010-00128); however, clean cap grout placed into Tank 16H was not tested.

The average 28-day compressive strength of tank grout placed into Tank 16H was 2,788 psi 

(192 bars), well above the value of 2,000 psi (138 bars) described in the closure module 

(SRR-CWDA-2013-00091). To represent the potential strength of Tank 16H clean cap grout, 

which was not tested directly, DOE provided statistics obtained from 500+-day compressive 

strength measurements of four grout cylinders that were cast from Z-Area Vault 4 grout batches. 

These compressive strengths ranged from 5,560 to 6,880 psi (383 to 474 bars) with an average 

of 6,202 psi (428 bars), much greater than the nominal 2,000 psi (138 bars) assumed by the 

HTF PA (SRR-CWDA-2015-00159; SRR-CWDA-2010-00128).

Details concerning the Tank 12H final configuration will be reviewed by NRC staff when the

Tank 12H Final Configuration report is complete. DOE should consider methods for improving 

grout volume estimates for the tanks, annuli, risers, and equipment to help ensure void space is 

fully grouted and better understand the nature of any remaining void space. DOE should 

consider archiving clean cap grout samples for 28-day compressive strength testing if it is used 

ever again to complete filling a waste tank.

Quality Assurance

The DOE quality assurance plan for Tank 16H, as described in SRR-LWE-2014-000150, is 

clear and, if implemented properly, should have ensured that Tank 16H was closed according to

plan, while meeting all regulatory process and documentation requirements. The NRC staff will

continue to evaluate whether the DOE quality assurance plan is being implemented effectively

during future onsite observation visits and technical reviews.

Teleconference or Meeting

During a teleconference on May 17, 2016, DOE and NRC discussed NRC staff questions

related to Tanks 16H and 12H grouting operations, including follow-up action items from the 

February 2016 onsite observation visit pertaining to grouting operations. Much of the meeting 

summary is discussed in the preceding evaluation. For additional details regarding the 

teleconference, please refer to the meeting summary (ADAMS Accession No. ML16167A237).
- 32 -

Follow-Up Actions

NRC staff will continue to monitor DOE’s bulk fill, equipment, and cooling coil grout formulations 

under Monitoring Factors 3.2 “Groundwater Conditioning via Reducing Grout,” 3.3, “Shrinkage 

and Cracking,” and 3.4, “Grout Performance” listed in NRC staff’s Tank Farm Monitoring Plan 

(ADAMS Accession No. ML15238A761) while focusing on the technical issues listed in this 

technical review report and on any new technical issues that arise. A comprehensive list of 

follow-up action items which includes items prepared following the May 17, 2016, 

teleconference, as well as new items identified in completing this technical review report is 

found below in Attachment 3.

Open Issues

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

provided to address the likelihood for preferential flow pathways to form through grout monoliths

due to shrinkage, cracking, and void space. NRC staff will continue to follow-up on this 

technical issue under 3.2 “Groundwater Conditioning via Reducing Grout,” and Monitoring 

Factor 3.3, “Shrinkage and Cracking” (See ADAMS Accession No. ML15238A761).

Conclusions

Due to the similarities in the grout formulation and approach to grouting Type I Tanks 5F, 6F, 

and 12H, Type II Tank 16H, and Type IV Tanks 18F and 19F, many of the conclusions resulting 

from the NRC staff’s previous reviews of documentation related to Tanks 5F, 6F, 18F and 19F 

remain relevant to the review of Tanks 16H and 12H grouting operations. Relevant major and 

minor conclusions from the Tanks 5F, 6F, 18F and 19F reviews are repeated below along with 

new conclusions from the Tanks 16H and 12H reviews.

Major Conclusions for Tanks 18F and 19F

• 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 

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). 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 ADAMS Accession No. 

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”. 
- 33 -

Minor Conclusions for Tanks 18F and 19F

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 

alkali-silica 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”). NRC staff also 

expects DOE to provide additional information on the potential for thermal cracking of the grout 

monolith for Tanks 18F and 19F. 

Major Conclusions for Tanks 5F and 6F

Major and minor conclusions from the Technical Review Report for Tanks 18F and 19F grouting 

were repeated in the Tanks 5F and 6F Technical Review Report. Additional conclusions (or 

additional detail regarding a previous conclusion) were also listed.

Additional Conclusions for Tanks 5F and 6F

• NRC staff observed grout with higher flowability in the Tanks 5F and 6F grouting 

operation videos compared to that placed into Tanks 18F and 19F due to the higher 

slump specified for use in tanks with cooling coils.

• NRC staff observed via video potential instances of bleed water segregation (e.g., 

mottling of grout that may be due to incomplete mixing or segregation, bright watery 

sheen at the leading edge of the fresh grout flow lobe, strong color differentials). While

NRC staff acknowledges the potential for these observations to be due to the Slick Willie 

pump priming agent, chromated water, or due to shadows caused by lighting angles, 

making that determination is subjective and the priming agent or water may have a 

potential impact on hydraulic properties and grout quality.

• DOE should minimize or eliminate excess water introduction to waste tanks, and provide 

evidence that introduction of excess water (e.g., in the form of Slick Willie) into Tanks 5F 

and 6F (and 18F and 19F) did not reduce the integrity of the tank grout to less than what 

is assumed in the FTF PA (SRS-REG-2007-00002, Revision 1).

• DOE should take reasonable measures to prevent future placement of out-ofspecification grout because inhomogeneity in the grout will affect flow in the monolith 

due to higher permeability zones receiving higher flow rates relative to surrounding 

zones.

• DOE should consider giving higher priority to development and testing of a shrinkage 

compensating tank grout formulation.

• Given that only approximately 50 percent of the tank annuli were visible in videos 

documenting annulus grouting, DOE should consider placing video cameras in all riser 

locations within tank annuli during grouting operations or else occasionally reposition 

video cameras into different available risers to improve visibility.
- 34 -

• Two of the failed cooling coils were only partially filled because DOE had not adequately 

cleaned the line prior to the fill, which allowed grout residue to plug the line. NRC staff 

notes that the lessons learned report (SRR-CWDA-2014-00015) provides several 

suggestions to prevent cooling coil grout addition line pluggage (e.g. increasing flush 

frequency, increasing flush water velocity, installing screens to prevent solids from 

plugging the line, increasing the pig diameter, and pre-charging the line with water). 

NRC staff will continue to monitor DOE’s actions to prevent plugging of the cooling coil 

grout addition line.

• Field-collected temperature data from actual waste tanks would provide valuable 

information regarding grout integrity given the potential for thermal cracking of large, 

hydrating grout monoliths.
- 35 -

Conclusions for Tanks 16H and 12H

• DOE should take reasonable measures to ensure a sufficient number of cement trucks 

are in rotation to optimize grout distribution throughout the tank and minimize mounding.

• DOE should take measures to continuously fill cooling coils with grout to ensure 

complete filling and to avoid creating grout blockages within intact coils that could have 

otherwise been fully filled (SRR-CWDA-2015-00159). Complete filling of cooling coils is 

needed to eliminate in-tank void space and preferential flow paths. DOE should 

continue to document related lessons learned and implement a path forward that will 

mitigate future occurrences.

• DOE should consider heat transfer requirements such that highly insulated cooling coil 

grout (i.e., in coils surrounded externally by tank grout) does not exceed its boiling 

temperature shortly after placement (WSRC-STI-2008-00298).

• NRC staff observed via Tank 16H grouting video instances of bleed water segregation.

Non-uniformly distributed excess water in the tank and annulus may have a potential 

impact on hydraulic properties and grout quality. DOE should remove excess ponded 

water from the tank before, during, and near the end of grouting operations, whenever 

aqueous ponds are present, to ensure adequate quality grout is placed into tanks and 

annuli. Alternatively, DOE could provide additional information to support a 

determination that the quantities of water present in the tanks during grouting do not 

adversely impact grout performance.

• More flowable clean cap grout used to fill remaining void space at the top of the Tank 

16H primary and annulus may have significantly different hydraulic properties compared 

to the rest of the bulk fill grout placed in the primary and annulus of Tank 16H. DOE 

should address the potential for either a capillary or permeability barrier to form due to 

the varying hydraulic conductivity of the clean cap and bulk fill grout used in Tank 16H.

• The results of the grout drop test report (RPT-5539-EG-0016) suggest the potential for 

segregation and bleed water production in the annulus of Tank 12H during initial 

grouting operations if grout was dropped into standing water. DOE should provide 

additional information regarding the quantity and performance impact of the presence 

standing water in Tank 12H during grouting.

• Lehigh Grade 120 slag used in the Tank 12H grout mix starting on the second day of 

grouting is expected to provide superior chemical performance compared to Holcim 

Grade 100 slag due to the higher activity index and increased reduction capacity. The 

compressive strength of the Grade 120 slag is also expected to increase due to a 

combination of small particle size and increased reactivity. DOE should evaluate 

differences in hydraulic conductivity between the Grade 100 and Grade 120 slag used to 

fill Tank 12H and any resulting performance impact.
- 36 -

Appendix A

Review Status of General Grout Documents:

C-SPP-F-00055. Ganguly, A. “Furnishing and Delivery of Tank Closure Grout.” Revision 4.

Aiken, South Carolina: Savannah River Remediation, LLC. December 20, 2012.

This document provided procurement specifications for furnishing and delivery of a low-paste, 

No. 8 stone (LP#8) reducing tank grout (see Attachment 5.5). This specification called (i) for 

use of slag cement that met the requirements of ASTM C989 Grade 100, and (ii) for its 

ASTM C1611 slump flow to be in the range of 26–30 in (66–76 cm). NRC staff reviewed 

Revision 2 and Revision 4 of this document in the technical review reports “U.S. DOE 

Documentation Related to Tanks 18 and 19 Final Configurations with an Emphasis on Grouting 

from Recommendations and Testing, to Final Specifications and Procedures” (ADAMS 

Accession No. ML13269A365) and “U.S. DOE Documentation Related to Tanks 5F and 6F

Final Configurations with an Emphasis on Grouting from Recommendations and Testing to Final 

Specifications and Procedures” (ADAMS Accession No. ML14342A784). The reader is referred 

to NRC staff’s prior technical reviews for summaries of the reference. Based on the outcome of

supplier deviation disposition request SDDR No. 13182, it is anticipated that a future Revision 5 

of this procurement specification will implement the following slag-related changes:

a) REPLACE “Grade 100” with “Grade 100 or Grade 120” at the end of Sections 3.2.3.3.A, 

3.2.3.3.B and 3.2.3.3.C (SDDR No. 13182).

b) ADD this sentence to the end of Section 3.2.3.3.A: “The recommended material sources 

for the Grade 120 Slag Cement shall be Lehigh Grade 120 (preferred) or Lafarge Grade 

120 (optional)” (SDDR No. 13182).

c) REPLACE Slag Cement Material Grade “100” by “100/120” in the Cementitious Material 

column of Attachment 5.5 (SDDR No. 13182).

C-SPP-F-00057. McCord, J.B. “Furnishing and Delivery of Cooling Coil Grout Dry Feeds.” 

Revision 2. Aiken, South Carolina: Savannah River Remediation, LLC. July 2014.

This document provides the procurement specifications for furnishing and delivery of cooling coil 

grout dry feeds, which include components Masterflow 816® grout and ASTM C989 Grade 100

slag cement provided either individually or together in a 9:1 ratio inside of SuperSaks designed 

to minimize moisture intrusion. Batched quantities may vary within ±2 percent of 1709.25 lbs 

(775 kg) for Masterflow 816 and 190 lbs (86 kg) for slag cement. The specification calls for 

documentation that demonstrates the grout components meet specification requirements. 

Any material substitutions relative to this specification, such as use of Grade 120 slag cement in 

lieu of Grade 100, would necessitate a Supplier Deviation Disposition Request (SDDR) and 

approval of SRR, as would any change in material supplier.

RPT-5539-EG-0016 (SRRA051386-2-A). Diener, G. “Savannah River Remediation 

Tank Closure Grout Assessment Final Report (Grout Drop Test Report).” Revision 0. 

Barnwell, South Carolina: EnergySolutions. December 16, 2014.

To assess potential changes to grouting operations being considered by SRR, this grout drop 

test report documented intermediate-scale field experiments conducted to examine physical 
- 37 -

effects of discharging grout via three different scenarios. The field experiments discharged 

7 cubic yards (i.e., one truckload) of SRS tank grout [26–30 in (66–76 cm) slump] into three 

20-ft (6-m)-diameter molds via each of these scenarios: (i) from a 42 ft (12.8 m) drop height 

using a tremie with free end positioned 5 ft (1.5 m) above an unyielding surface, (ii) from a 42 ft 

(12.8 m) drop height using a tremie with free end positioned approximately 5 ft (1.5 m) above a 

4-in (10-cm)-deep pool of water, and (iii) from a 42 ft (12.8 m) drop height without a tremie, 

allowing tank grout to freefall onto an unyielding surface. Note that a tremie is a long hose 

connected to the grout distribution pipe that is used by DOE to reduce the drop height of grout 

into the tank. The first two tests used two 37-ft (11.3-m)-long tremies equivalent to those used 

for tank closure operations. Each experiment was visually recorded by video camera, which 

were provided to NRC staff for review.

The baseline for tank grout discharge (represented by Test 1) is placement into a tank or 

annulus via a tremie with free end located within 5 ft (1.5 m) above a dry tank floor, dry grout 

surface or fresh grout surface. Test 2, which discharged grout into standing water via a tremie, 

represented non-removal of cooling coil flushwater prior to grouting operations. Tests 3A and 

3B, which discharged grout from a 42-ft (12.8-m) drop height without a tremie were of potential 

interest as a worker dose-limiting option. A fourth test that would have examined physical 

effects of allowing tank grout to freefall from a drop height of 42 ft (12.8 m) into a 4-in 

(10-cm)-deep pool of water was not undertaken due to unanticipated failure of a containment 

mold during the attempted completion of the first grout freefall test (Test 3A).

Grout discharge rates were not constant during the grout drop tests and were inconsistent with 

the intended discharge range of 1.17 to 1.23 cubic yards per minute. Grout was discharged 

most rapidly during baseline Test 1 (1.52 cubic yards per minute), most slowly during Test 2 

(0.80 cubic yards per minute), and at intermediate rates during Tests 3A and 3B (0.88 and 

1.27 cubic yards per minute).

The report indicates that there was no visual evidence of bleed water segregation during Test 1 

grout placement; however, the report goes on to provide photographs of cylindrical samples 

taken from the grout monolith and indicated that these photographs showed a slight decrease in 

aggregate at the top of T1-9-O-1 (the Test 1 sample collected at the 9 foot radius position). 

During Test 2, the authors report ample visual evidence of bleed water segregation during grout 

placement, as well as later based on analysis of photographs of cylindrical samples and optical 

microscopy assessments of aggregate distribution. During Tests 3A and 3B, the grout stream 

leaving the nozzle was described as dispersing into small clumps of grout as it fell through the 

air with heavy splattering against the containment walls after impacting the steel plate16. The

authors of the report indicated that splattering and splashing were significantly reduced after the 

grout depth was sufficient to adsorb the impact of the falling grout. The report authors stated 

that they observed no visual evidence of bleed water segregation during Tests 3A/3B and 

optical microscopy samples were consistent with this observation.

The physical effects of the grout drop test scenarios were evaluated on core-drilled grout 

samples, recovered after a minimum of 3 weeks of set time, by conducting measurements of 

 16 Four circular containment areas were prepared by placing an 8 foot x 10 foot steel plate (1” thick) on the ground 

which was intended to represent the unyielding surface of the tank bottom. A layer of sand was placed around the 

steel plates to form a level base so that a 20 foot diameter above ground pool could be erected on top of the steel 

plate.
- 38 -

their compressive strength, saturated hydraulic conductivity, and aggregate distribution after a 

28-day or longer set time. Grout cylinders were removed from locations 1, 5, and 9 ft (0.3, 1.5, 

and 2.7 m) from the center of each monolith to ascertain if grout properties had radial 

dependencies. Compressive strength exhibited radial dependencies at 28 days for Tests 1 and 

2. Test 2, had the lowest compressive strengths after 28 days. In general, compressive 

strength increased with curing time for Tests 1 and 3 (compressive strength was only measured 

after a 28 day curing time for Test 2). For Test 1, five of six grout samples tested after a 90-day 

set time met the compressive strength PA requirement of 2000 psi (138 bars); the other was 

thought to have failed prematurely due to having a chipped surface. When cylinders from each 

monolith were tested for hydraulic conductivity at 7 weeks (i.e., ~49 days) post-placement, 

saturated hydraulic conductivity increased with radius. Test 3B exhibited the highest hydraulic 

conductivities at every radius. Test 2, which exhibited more significant bleed water segregation 

compared to other tests, exhibited the lowest hydraulic conductivities at every radius, yet 

exhibited the largest relative increase in the property between radii of 5 and 9 ft (1.5 and 2.7 m). 

The authors indicated that calcium-silicate-hydrate formation during continued hydration in high 

relative humidity was responsible for healing of microcracks that were thought to have been 

caused due to drilling of the specimens. CSH formation allowed for improved compressive 

strength and saturated hydraulic conductivity with additional curing time. Test 3B yielded 

saturated hydraulic conductivities with less radial dependency when measured 18 weeks (i.e., 

~126 days) post-placement and by that time, conductivity was decreasing with increasing 

radius. Optical microscopy samples extracted from Test 1 and 3B monoliths generally indicated 

uniform distribution of aggregate throughout each sample, except for a slight decrease in 

aggregate observed at the top of sample T1-9-O-1, collected at a 9 ft (2.7 m) radius. In 

contrast, core samples T2-5-O-1 and T2-9-O-1 from the Test 2 monolith exhibited distinct 

segregation of aggregate below from fines above with increasing radius from the central drop 

point. Approximately the top 2.4 in (6 cm) of material comprising sample T2-9-O-1 was 

generally devoid of pea gravel and enriched in fines.

The authors concluded that (i) discharging tank grout without a tremie would not impact the 

properties of the cured grout because both compressive strength and saturated hydraulic 

conductivity likely would be within the grout specification (e.g., SRNL-RP-2011-00977) and 

segregation would be unlikely, but that (ii) discharging tank grout into 4 in (10 cm) of ponded

water is not recommended because significant segregation would occur and the grout would

likely not meet the grout specification requirements for compressive strength. They allowed that 

shallower ponded water might yield less bleed water segregation and that additional testing 

would be necessary to support such a finding.

SDDR No. 13182. “Section 3.2.3.3 States the Slag Cement Must Meet ASTM C989, 

Grade 100. This Slag is No Longer Available in the Southeast, U.S.A. Change Specification to 

Allow for the Use of ASTM 989, Grade 120 Slag. (Supplier Deviation Disposition Request).” 

Augusta, Georga: Argos Ready Mix, LLC. March 30, 2015.

This supplier deviation disposition request (SDDR) documented DOE’s disposition of a 

proposed deviation to the tank grout procurement specification (C-SPP-F-00055, Revision 4) 

due to a limited supply of Grade 100 ground granulated blast furnace slag cement. Dispositions 

of SDDRs must be handled as described in procurement specifications. This SDDR specifically 

requested a deviation that would allow use of Lehigh Hanson (Cape Canaveral) Grade 120 slag 

cement, or Grade 120 slag from another source in the southeastern United States. The request 

occurred because production of Holcim, Inc. (Birmingham, Alabama) Grade 100 slag, previously 
- 39 -

used at SRS as a component in saltstone, tank grout, and clean cap grout, had ceased 

(VSL-15R3740-1). Argos, who prepared the SDDR, provided 12 months of Lehigh Hanson’s 

Grade 120 slag ASTM C989 test reports to support the request. SRR agreed to the deviation 

request, allowing use of LeHigh Hanson Grade 120 slag to replace Holcim, Inc. Grade 100. 

A future Revision 5 of C-SPP-F-00055 is expected to formally include related changes to the 

specification for slag cement. Vitreous State Laboratory recommended LeHigh Hanson Grade 

120 as the first choice, and Lafarge Grade 120 slag as the second-best choice amongst slag 

materials tested (VSL-15R3740-1).

SRNL-STI-2012-00546. Cozzi, A.D. and B.R. Pickenheim. “Impact of Standing Bleed Water on 

Saltstone Placement.” Revision 0. Aiken, South Carolina: Savannah River National 

Laboratory. September 2012a.

This report was the first of two that documented a study of the effects of excess water, during 

the early hydration process, on physicochemical properties of reducing grout. The presence or 

absence of aqueous environments during the hydration and hardening of reducing grout may 

impact properties important to waste isolation. For example, grout that hydrates and hardens in 

the absence of standing water may undergo local surface oxidation, resulting in increased

leachability of redox-sensitive species. In contrast, while standing water may be available for 

potential incorporation into subsequent grout placements, excess water may degrade grout 

properties such as homogeneity by exacerbating the effects of bleed water segregation. 

Eight grout types studied by Cozzi and Pickenheim (2012a,b) were variations on waste-isolating 

saltstone representing different conditions that may occur during processing or after it has been 

placed and begins hardening. Two water-to-premix ratios (0.60 and 0.64) were tested. 

Two grout types were fully exposed to ambient air after 7 days, and the other six were kept in 

humid environments inside sealed molds. Five of the grouts were poured into empty molds, 

with one being capped with standing water post-gel; the other three were poured into molds that 

contained salt solution (i.e., “standing water). After 28 days, grout specimens representing the 

eight types were de-molded and leached according to the ANSI/ANS 16.1 standard test. 

The two grout types exposed to ambient air during hydration exhibited the greatest tendency to 

leach incorporated constituents, as evidenced by having both the highest leachate electrical 

conductivity values and the lowest Leachability Indices for potassium, sodium, rhenium, nitrite, 

and nitrate. The leachability of grout placed in standing water, however, was unaffected. 

Duplicate grout specimens representing the eight types were de-molded, sliced into four disks, 

and the density of each disk was analyzed to understand the effects of bleed water segregation 

on grout homogeneity. Two grout types poured into 10 percent excess salt solution exhibited a 

4 to 5 percent increase in density from top to bottom of each specimen, which is indicative of

bleed water segregation and settling. The authors concluded that premature drying of saltstone 

was detrimental to its quality with respect to isolating waste, but that the presence of excess

water may exacerbate settling that causes nonhomogeneity.

SRNL-STI-2012-00576. Cozzi, A.D. and B.R. Pickenheim. “Impact of Standing Water on 

Saltstone Placement II - Hydraulic Conductivity Data.” Revision 0. Aiken, South Carolina: 

Savannah River National Laboratory. October 2012b.

This report was the second of two that documented a study of the effects of excess water, 

during the early hydration process, on physicochemical properties of reducing grout. 

The presence or absence of aqueous environments during the hydration and hardening of 

reducing grout may impact properties important to waste isolation. A relatively dry environment 
- 40 -

may be favorable for shrinkage crack formation that would increase hydraulic conductivity, but 

excess standing water may also result in development of heterogeneous distributions of density 

and hydraulic conductivity. Eight grout types studied by Cozzi and Pickenheim (2012a,b) were 

variations on waste-isolating saltstone representing different conditions that may occur during 

processing or after it has been placed and begins hardening. Two water-to-premix ratios 

(0.60 and 0.64) were tested. Two grout types were fully exposed to ambient air after 7 days, 

and the other six were kept in humid environments inside sealed molds. Five of the grouts were 

poured into empty molds, with one being capped with standing water post-gel; the other three 

were poured into molds that contained salt solution (i.e., “standing water). After 28 days, each

specimen was sliced in half, and the saturated hydraulic conductivity of each half was measured 

to determine if the previously observed density gradients (SRNL-STI-2012-00546) could be 

correlated with hydraulic conductivity gradients. The two grout types exposed to air during 

hydration had hydraulic conductivities that were three orders of magnitude greater than those of 

specimens hydrated in a humid environment, perhaps due to development of microcracks. 

Among the other six grout types, neither the water-to-premix ratio nor excess standing water 

had appreciable effects on hydraulic conductivity. However, seven of the eight grout types 

exhibited density-related depth-dependencies of hydraulic conductivity, with higher densities 

being correlated to lower hydraulic conductivities. However, the authors concluded that 

although a depth-dependent effect on hydraulic conductivity was detectable, grout quality was 

not meaningfully degraded by bleedwater segregation and settling given the natural variation in 

hydraulic conductivity that is expected within saltstone from the influence of variable process 

conditions and environmental conditions that may occur. Moreover, they concluded that 

hydration and hardening of reducing grout in a moist environment is critical to development of 

high-quality properties, such as the PA-assumed low values of hydraulic conductivity.

SRNL-STI-2012-00578. Langton, C.A., et al. “Relationship Between Flowability and 

Tank Closure Grout Quality.” Revision 0. Aiken, South Carolina: Savannah River National 

Laboratory. October 2012.

This report evaluated the relationship between tank grout flowability and compressive strength

to determine whether the maximum acceptable slump for tank grout could be increased from 

28 to 30 in (71 to 76 cm) to improve grout flowability and decrease mounding without negatively 

impacting grout quality. Langton et al. concluded that the compressive strengths of Tanks 18-F 

and 19-F quality control test specimens were not a function of slump over the range tested [i.e., 

from 24 to 28 in (61 to 71 cm)] and that the upper limit for slump measured per ASTM C1611 

could be increased by an additional 2 in (5 cm) without negatively affecting grout quality. 

The authors also recommended that the grout delivery rate be increased by (i) using a higher 

capacity grout pump and (ii) through more continuous discharge to improve grout distribution 

throughout tanks, particularly tanks containing significant obstructions such as cooling coils. 

While this report discussed a potential increase in the grout drop height from ≤5 ft (≤1.5 m) 

to ≤10 ft (≤3 m) intended to impart greater kinetic energy to the grout and improve its in-tank 

distribution, the authors indicated that additional testing was necessary to determine whether 

bleed water segregation, which would negatively impact grout quality, would be enhanced if the 

grout drop height was increased from 5 to 10 ft (1.5 to 3 m).
- 41 -

USQ-HTF-2015-00300. Voegtlen, R.O. “Supplier Deviation Disposition Request (SDDR) 

Number 13182–Deviation from Specification C-SPP-F-00055, Revision 4 (Technical Review 

Package).” Revision 0. Aiken, South Carolina: Savannah River National Laboratory. 

September 10, 2015.

This technical review package contains a series of related reports, including a Design Authority 

Technical Review (DATR) (originated April 17, 2015 and signed September 2, 2015), an 

Unreviewed Safety Question Review (USQS) report (originated April 17, 2015 and signed 

September 2, 2015), a Consolidated Hazard Analysis Process (CHAP) Screening (originated 

April 17, 2015 and signed September 10, 2015), a description of the proposed action in an 

attachment, and a UWMQ Determination. Specification C-SPP-F-00055, Revision 4, Section 

3.2.3.3.A requires that ground granulated blast furnace slag cement used to batch tank grout 

meet the requirements of ASTM C989, Grade 100. SDDR No. 13182, initiated in March 2015,

proposed a deviation to allow use of Grade 120 slag cement in lieu of Grade 100 (i.e., the 

“proposed action”). Because the deviation or proposed action would alter the tank grout 

formulation, the UWMQ Determination was initiated and an UWMQ Evaluation (UWMQE) was 

performed. UWMQE-SRR-CWDA-2015-00088, “Use of Grade 120 Slag in Tank Closure Grout 

(USQ-HTF-2015-00300)” was approved and the deviation was determined acceptable because 

its implementation would have no adverse impact on the facility or its systems, nor would it 

compromise PA conclusions.

VSL-15R3740-1. Gong, W. et al. “Investigation of Alternate Ground Granulated Blast Furnace 

Slag for the Saltstone Facility (Final Report).” Revision 0. Washington, DC: Vitreous State 

Laboratory, The Catholic University of America. August 26, 2015.

This report describes testing performed for SRR to assess characteristics of grout specimens 

prepared using alternative slag cements. Granulometry, reductive capacity, viscosity, yield 

stress, temporal gelation behavior (i.e., “gel time” at which point a grout slurry is no longer 

pourable), and heat of hydration (through the first 12 days post-placement) test results were 

obtained from alternative slag cements and from grout specimens prepared with alternative slag 

cements, including: Holcim, Inc. Grade 100 (control); Lehigh Hanson Grade 120; Lafarge 

Grade 120; Argos Grade 120; and Essroc Grade 100 (Essroc Grade 100 is misclassified 

because it meets Grade 120 requirements of ASTM C989). In general, substituting a 

Grade 120 slag for Grade 100 should result in higher compressive strength and lower hydraulic 

conductivity specimens due to the smaller particle size and enhanced reactivity of Grade 120. 

Differences in slag chemistry may also impact fresh and hardened properties of cementitious 

grouts, which could affect long-term performance. Salt waste simulant was combined with dry 

premixes at a water-to-premix ratio of 0.6 typical of saltstone, rather than at a ratio of 0.5 typical 

of clean cap grout (such as that placed into Tank 16H). Based upon heat release, slag 

reactivity of the five alternatives ranked as follows: Holcim (lowest) < Lehigh Hanson < Argos 

< Lafarge < Essroc (highest). Argos and Essroc slags were not recommended for use due to 

(i) Argos offering a substantially lower reductive capacity than the other materials and (ii) Essroc 

exhibiting the greatest heat release. Lehigh Hanson was preferred due to its (i) high reductive 

capacity, which was 12 percent greater than Holcim, and (ii) low heat release. Lafarge was 

considered the next-best alternative.
- 42 -

WSRC-STI-2008-00172. Harbour, J.R., et. al. “Closure of HLW Tanks—Formulation for a

Cooling Coil Grout.” Revision 0. Aiken, South Carolina: Savannah River National Laboratory.

April 2008.

The document summarized the development of the cooling coil grout formulation [90 wt%

Masterflow 816 (BASF Corporation, Shakopee, Minnesota) and 10 wt% ground granulated blast

furnace slag, Grade 100] and recommended a laboratory-scale investigation be performed to

determine the impact of operational variations such as temperature and mixing time on cooling 

coil grout properties. NRC staff reviewed Revision 0 of this document in the technical review 

report “U.S. DOE Documentation Related to Tanks 5F and 6F Final Configurations with an 

Emphasis on Grouting from Recommendations and Testing to Final Specifications and 

Procedures” (ADAMS Accession No. ML14342A784). The reader is referred to NRC staff’s 

prior technical review for a summary of the reference.

WSRC-STI-2008-00298. Hansen, E.K. et al. “Closure of HLW Tanks—Phase 2, Full Scale 

Cooling Coils Grout Fill Demonstrations.” Revision 0. Aiken, South Carolina: Savannah River 

National Laboratory. June 2008.

The document described full-scale testing of the recommended cooling coil grout formulation. 

NRC staff reviewed this document in the technical review report “U.S. DOE Documentation 

Related to Tanks 5F and 6F Final Configurations with an Emphasis on Grouting from

Recommendations and Testing to Final Specifications and Procedures” (ADAMS Accession No. 

ML14342A784). The reader is referred to NRC staff’s prior technical review for a summary of 

the reference.

Review Status of Tank 18F and 19F Documents:

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 1. 

Aiken, South Carolina: Savannah River National Laboratory. April 2013.

This report summarized the development of a zero bleed tank grout formulation and testing of 

specimens. The NRC staff reviewed Revision 0 of this document in the technical review report 

“U.S. DOE Documentation Related to Tanks 18 and 19 Final Configurations with an Emphasis 

on Grouting from Recommendations and Testing, to Final Specifications and Procedures” 

(ADAMS Accession No. ML13269A365). Later, staff also reviewed Revision 1 of this document 

in the technical review report “U.S. DOE Documentation Related to Tanks 5F and 6F Final

Configurations with an Emphasis on Grouting from Recommendations and Testing to Final 

Specifications and Procedures” (ADAMS Accession No. ML14342A784). In Revision 1, DOE 

corrected a value in Table 3-6 {“Moisture retention as a function of applied pressure for [grout

formulas] LP#8-016 and LP#8-020”} that followed a correction in a contractor test report. At a 

March 26–27, 2014 onsite observation visit, DOE staff indicated that moisture retention data, 

which had been forecast by this report to be obtained in the near future over the high-pressure 

range from 15 to 45 bars, were never obtained due to inadequate funding levels (ADAMS 

Accession No. ML14342A784). Revisions 0 and 1 are identical in all other respects and the 

reader should refer to NRC staff’s Revision 0 technical review for a summary of the reference.
- 43 -

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.

This report summarized the results of equipment fill mock up testing, which was focused on 

internally grouting the Advanced Design Mixer Pump and pipes of 1-in (2.5-cm)-diameter 

and greater. NRC staff reviewed this document in the technical review report “U.S. DOE 

Documentation Related to Tanks 18 and 19 Final Configurations with an Emphasis on Grouting 

from Recommendations and Testing, to Final Specifications and Procedures” (ADAMS 

Accession No. ML13269A365). The reader is referred to NRC staff’s prior technical review for a 

summary of the reference.

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.

This report documents laboratory testing performed to identify an equipment grout formulation. 

NRC staff reviewed this document in the technical review report “U.S. DOE Documentation 

Related to Tanks 18 and 19 Final Configurations with an Emphasis on Grouting from 

Recommendations and Testing, to Final Specifications and Procedures” (ADAMS Accession 

No. ML13269A365). The reader is referred to NRC staff’s prior technical review for a summary 

of the reference.

SRNL-STI-2011-00749. “Tank 18F and 19F Tank Fill Grout Scale Up Test Summary.” 

Revision 0. Aiken, South Carolina: Savannah River National Laboratory. December 2011.

This report documents a bulk fill scale-up test of the tank grout formulation, which was intended 

to demonstrate proportioning, mixing, and transportation of material produced in a full-scale 

ready-mix concrete batch plant. In addition, the tank grout was characterized with respect to 

fresh properties, thermal properties, and compressive strength as a function of set time. 

NRC staff reviewed this document in the technical review report “U.S. DOE Documentation 

Related to Tanks 18 and 19 Final Configurations with an Emphasis on Grouting from 

Recommendations and Testing, to Final Specifications and Procedures” (ADAMS Accession 

No. ML13269A365). The reader is referred to NRC staff’s prior technical review for a summary 

of the reference.

SRR-CES-2012-00031. “Summary Report of the Equipment Grout Mock-up Test.” Revision 0.

Aiken, South Carolina: Savannah River Remediation, LLC. April 13, 2012.

This report summarized results obtained from a scaled-up equipment grout mock-up test 

(SRNL-STI-2011-00564). NRC staff reviewed this document in the technical review report 

“U.S. DOE Documentation Related to Tanks 5F and 6F Final Configurations with an Emphasis 

on Grouting from Recommendations and Testing to Final Specifications and Procedures” 

(ADAMS Accession No. ML14342A784). The reader is referred to NRC staff’s prior technical 

review for a summary of the reference.
- 44 -

Review Status of Tank 5F and 6F Documents:

2013-NCR-15-WFC-0006. “F Tank Farm Grout - Tank 6 (Non-Conformance Report).” 

Aiken, South Carolina: Savannah River Remediation. October 2, 2014;

USQ-FTF-2013-00317. “New Data – Use-As-Is Disposition of the Non-Conformance Report 

(NCR) 2013 NCR-15-WFC-0006 ‘F Tank Farm Grout – Tank 6.’ Non-Conformance Tank 6 

Grout Water Content Higher than Allowed per C-SPP-F-00055, Rev. 4 ‘Furnishing and Delivery 

of Tank Closure Grout.’” Revision 0. Aiken, South Carolina: Savannah River Remediation. 

October 3, 2014; and tank grout batch tickets for September 19, 2013.

Altogether, these records documented that 25 batches of tank grout placed into Tank 6 on 

September 19, 2013, had water content approximately 3 percent greater than allowed by the 

procurement specification “Furnishing and Delivery of Tank Closure Grout” (C-SPP-F-00055). 

NRC staff reviewed the non-conformance report (2013-NCR-15-WFC-0006), waste 

management question evaluation (USQ-FTF-2013-00317), and associated tank grout batch 

tickets in the technical review report “U.S. DOE Documentation Related to Tanks 5F and 6F

Final Configurations with an Emphasis on Grouting from Recommendations and Testing to 

Final Specifications and Procedures” (ADAMS Accession No. ML14342A784). The reader is 

referred to NRC staff’s prior technical review for a summary and evaluation of the references.

SRR-CWDA-2014-00015. Cantrell, J.R. “Tank 5 and 6 Grouting Project Lessons Learned.”

Revision 0. Aiken, South Carolina: Savannah River Remediation. February 6, 2014.

NRC staff reviewed DOE’s lessons learned from Tank 5F and 6F grouting operations in the 

technical review report “U.S. DOE Documentation Related to Tanks 5F and 6F Final

Configurations with an Emphasis on Grouting from Recommendations and Testing to Final 

Specifications and Procedures” (ADAMS Accession No. ML14342A784). Lessons learned 

during grouting operations at Tanks 5F and 6F resulted in the following recommendations: (i) to 

minimize tremie adjustment and radiation exposure, evaluate effects of increasing the grout 

drop height; (ii) work with camera crew to ensure satisfactory camera placement; (iii) use less 

Slick Willie during the final lifts to minimize potential for unincorporated liquid; (iv) prevent 

cooling coil grout addition line pluggage through increasing flush frequency, increasing flush 

water velocity, installing screens to prevent solids from plugging the line, increasing the pig 

diameter, and pre-charging the line with water. To minimize unintended use of out-ofspecification grout, the report recommended refresher training for personnel reviewing batch 

tickets to aid identification of nonconforming grout and to modify procedures to include a specific 

review of formulation values at delivery.

SRR-LWE-2013-00214. Chandler, T.L. “Engineering Path Forward – Tanks 5 & 6: Record of 

Additional Grouting Actions. Revision 0. Aiken, South Carolina: Savannah River Remediation. 

February 10, 2014.

To decrease the likelihood of discovering unexpected conditions during future grouting efforts 

through identification of potential causes, this report documented several situations that 

occurred during the process of completing operational closure of Tanks 5F and 6F. The report

outlined (i) events that occurred, (ii) actions taken or planned to be taken to properly manage 

such events, and (iii) the reasoning behind decision(s) made. The situations enumerated were:
- 45 -

1. Tank 6, Riser 4 transfer jet not disassembled as planned; upon discovery, decision was

made to grout the equipment to eliminate a potential vertical fast flow path.

2. Near completion of tank grouting, displaced liquid was found in several of the tank risers 

of both tanks; upon discovery, a new work order (Work Order No. 01199254-65) was 

issued to allow, if required, the liquid to be removed. The liquid levels present were 

estimated at less than a few inches to more than 12 inches (cm) within the risers. 

The report stated, however, that “as a result of liquid reconstitution during grout addition 

and evaporation, the liquid level was deemed negligible and its removal unnecessary.”

3. Between the two tanks, five of 72 cooling coils could not be fully grouted, and two other 

coils did not receive the intended 132 L (35 gal) of excess grout required to transition 

them from being filled with flushwater to filled with grout. Reasons for incomplete filling 

included blockage of grout addition lines, high radiation levels during operations, 

blockage of perforated (slightly damaged) cooling coils with intruded tank grout, and 

inadequate coil grout batch size. In response, actions were taken to minimize the 

likelihood of line blockages with hardened grout and two batches of coil grout were 

prepared in advance of each subsequent coil grouting operation. It was decided that 

these partially filled coils did not represent a change to the assumed waste tank final 

equipment configuration. The FTF PA and supporting documentation (e.g., 

SRR-CWDA-2012-00051) assumed that coils would be filled only to the extent practical 

and recognized the potential for coils to be partially filled.

Work Order No. 01199254-65. “Tanks 5–6 Pump Standing Water in Risers.” Revision 0.

Aiken, South Carolina: Savannah River National Laboratory. December 10, 2013.

This work order instructed workers on use of a pump to remove excess liquid from Tank 5F and 

6F risers near the end of grouting activities, if necessary. NRC staff reviewed this work order in 

technical review report: “U.S. DOE Documentation Related to Tanks 5F and 6F Final

Configurations with an Emphasis on Grouting from Recommendations and Testing to Final 

Specifications and Procedures” (ADAMS Accession No. ML14342A784). The reader is referred 

to NRC staff’s prior technical review for a summary and evaluation of the reference.

Review Summaries of Tank 16H Documents:

C-SPP-Z-00012. Patel, R. “Vault 4 Clean Cap Grout (Procurement Specification).” Revision 1. 

Aiken, South Carolina: Savannah River Remediation, LLC. March 20, 2014.

This document provided procurement specifications for furnishing and delivery of three 

alternative mix designs for clean cap grout (see Attachment 5.5 for formulations, all of which 

have dry feed 45:45:10 flyash:slag:cement ratios), only one of which was selected for use in 

Saltstone Disposal Units. The specification called for a measured slump flow (ASTM C1611) 

within the working range of 26–38 in (66–97 cm) as a field test acceptance criterion for clean 

cap grout. Other procurement specifications included trial batching to demonstrate the 

production grout would meet specification requirements, plant and delivery schedule capacity, 

mix time, drum revolution, and grout temperature limits at point of delivery, provision of batch 

tickets, inspection reports, and test results containing specified data, as well as quality 

assurance, record-keeping, and testing laboratory requirements. Collection of samples for 

ASTM C39 compressive strength testing was not addressed in the procurement specification for 

clean cap grout. This document is relevant to Tank 16H grouting operations because clean cap 

grout was placed above its mounded tank grout to fill remaining void space.
- 46 -

Clean Cap Grout Design Quantity per Cubic Yard based on Batch Ticket #042239; w:p = 0.50

Type I/II Portland 

Cement (lbs)

Class F

Flyash (lbs)

Grade 100 GGBF

Slag Cement (lbs) Water (gal)

174 868 868 114.5

SRR-CWDA-2013-00091. “Industrial Wastewater Closure Module for Liquid Waste Tank 16H, 

H-Area Tank Farm, Savannah River Site.” Revision 1. Aiken, South Carolina: Savannah River 

Remediation, LLC. April 2015.

This report is one of the key Tier 2 closure documents for Tank 16H that supports Tier 2 

closure authorization, which is DOE-SR’s final authorization to proceed with permanent 

stabilization of the waste tank system. Section 7.3 of this closure module described anticipated 

Tank 16H grouting operations, and suggested that grouting of the annulus ventilation duct may 

require an unspecified grout more flowable than tank grout. Notably, Section 7.3.2 of the 

document indicated awareness of a potential need to provide access points into the tank to 

address bleed water build-up. Grouting plans described by the closure module were summaries 

of more detailed information contained in the “Tank 16H Grout Strategy” (SRR-LWE-2014-

00013) document; therefore, the reader is referred to the in-depth summary of SRR-LWE-2014-

00013 contained herein for information on planned Tank 16H grouting operations.

SRR-CWDA-2014-00011. Smith, F.M. “Evaluation of Vendor Supplied Clean Cap Material for 

Saltstone Disposal Units.” Revision 0. Aiken, South Carolina: Savannah River Remediation, 

LLC. March 2014.

The report was prepared to support issuance of an Unreviewed Waste Management

Question Evaluation (UWMQE) that assessed clean cap grout proposed for use in Saltstone 

Disposal Units at the Saltstone Disposal Facility. This report is relevant to Tank 16H grouting 

operations because clean cap grout was placed in the tank above mounded tank grout to fill 

remaining void space. The report states that clean cap grout is known to form bleed water, but 

that the amount of bleed had not been defined for normal clean cap operations. Vitreous State 

Laboratory (VSL-14R3330-1) tested grouts mixed with the standard dry feeds while varying the 

water-to-premix ratio and adding NaOH solution to understand their resulting properties (e.g., 

total bleed, re-absorbtion time, flowability, and uniformity). The water-to-premix ratio was 

reduced from 0.59 for saltstone (SRNL-STI-2012-00558) to either 0.45 or 0.50 (C-SPP-Z00012) for the proposed clean cap grout formulations to reduce bleed; however, this also 

reduced its flowability (see also SRNL-STI-2012-00558, sample WP023). Use of a caustic 

additive [6 wt% (1.6M) NaOH], intended to simulate the average concentration of free hydroxide 

in decontaminated salt solution, decreased total bleed while maintaining grout flowability. 

Finally, saturated hydraulic conductivity decreased with use of lower water-to-premix ratios 

(SRNL-STI-2012-00558).

SRR-CWDA-2015-00096. Layton, M. “Unreviewed Waste Management Question Evaluation—

Use Alternative Tank 16 Fill Grout (Per Specification C-SPP-Z-00012).” Revision 1. Aiken, 

South Carolina: Savannah River Remediation, LLC. September 2015.

This form described a proposed action and evaluation of the action to use flowable clean cap 

grout (C-SPP-Z-00012) to complete Lifts 5 and 6 near and at the top of Tank 16H. Clean cap 

grout was proposed to provide an approximately 2-ft (0.6-m)-thick cap on mounded tank grout 

in the primary and annulus of Tank 16H to minimize potential for voids to remain after grouting 
- 47 -

operations had been completed. DOE estimated that the amount of clean cap grout placed in 

the primary and annulus would not exceed 84,000 and 10,280 gal, respectively. Clean cap 

grout was not expected to meet all assumed mechanical and chemical properties for tank grout 

that had been specified in the HTF PA (SRR-CWDA-2010-00128), and therefore placement of 

clean cap grout could result in a condition or impairment to critical design features for the waste 

tank outside the bounds of critical PA assumptions. To examine the impact of this action, DOE 

undertook an evaluation of the potential to meet tank closure performance objectives using the 

alternative grout fill (SRR-CWDA-2015-00100). Although clean cap grout may not perform as 

assumed by the PA, DOE suggested that clean cap grout may perform satisfactorily such that 

the Tank 16H closure performance objectives could be met despite any violation(s) of PA 

assumptions. The UWMQE Peer Reviewer concurred with UWMQEO’s conclusion and also 

found that placement of clean cap grout would comply with the WD Basis Document 

(DOE/SRS-WD-2014-001). Final reviewer signatures were obtained on September 8, 2015, 

more than one week after placement of clean cap grout into Lift 5 of Tank 16H began on 

August 31, 2015.

SRR-CWDA-2015-00100. “Evaluation of the Use of an Alternative Tank 16 Fill Grout 

(Per Specification C-SPP-Z-00012) (Interoffice Memorandum to G.C. Arthur from M.H. Layton).” 

Revision 2. Aiken, South Carolina: Savannah River Remediation, LLC. September 2015.

This interoffice memorandum was included as a supporting reference to SRR-CWDA-2015-

00096. The memo documents DOE’s evaluation of the impact of switching from placement of 

tank grout to a more flowable clean cap grout (used in the saltstone disposal facility) in the final 

Tank 16H primary and annulus grout lifts, Lifts 5 and 6, respectively. Less than 10 percent (a 

maximum of 84,000 gal) of the total volume of the primary (1,030,000 gal) would be filled with 

clean cap grout and up to 10,280 gal would be placed in the annulus.

The HTF PA (SRR-CWDA-2010-00128) contained assumptions about the chemical and 

physical properties and performance of tank grout that would affect waste tank stability, 

protection from inadvertent intrusion and waste release. In regard to chemical properties, DOE 

concluded that placing clean cap grout above tank grout during completion of Lifts 5 and 6 in 

Tank 16H would not negatively impact the reductive capacity of grout placed in the tank

because clean cap grout has a greater weight percent ground granulated blast furnace slag 

cement than tank grout (i.e., 45 weight percent in clean cap grout versus 30 weight percent in 

tank grout). 

In regard to physical properties, this report indicated that clean cap grout may not attain the 

minimum adequate compressive strength of 2000 psi (138 bars) assumed by the HTF PA (SRRCWDA-2010-00128; cf. SRR-CWDA-2015-00160). But because its use would both minimize 

void space and be volumetrically limited, DOE concluded that tank stability and the inadvertent 

intruder barrier provided by the two-component Tank 16H grout monolith would be maintained. 

Additionally, the hydraulic properties of clean cap grout are consistent with those assumed by 

the PA. The mean saturated hydraulic conductivity of three Vault 4 clean cap grout specimens, 

2.2 × 10−9 cm/s (Amec Foster Wheeler, 2015; SRR-CWDA-2015-00160) is only slightly greater 
- 48 -

than that of tank grout (2.1 × 10−9 cm/s; SRR-CWDA-2010-00128, Table 4.2-28), and this 

difference likely would result in only slightly faster water infiltration to the waste layer; however, 

the clean cap grout layer would be thin and located at the top of the tank, such that the overall 

effect of this higher conductivity layer on flow out of the contamination zone may be limited. 

DOE staff explored these effects on waste release using what DOE indicated was a 

conservative HTF Goldsim model that was run deterministically with an increased infiltration rate 

of 16.45 in/yr (compared to 11.67 in/yr) and with early hydraulic degradation of the grout (flow 

run 17 in Table 5.6-7 of the HTF PA). The resulting impact on peak contaminant release was 

minor (SRR-CWDA-2015-00100; Figs. 1 and 2). The 1-m and 100-m peak doses remained well

below the peak HTF doses documented in the Tank 12 Special Analysis (SRR-CWDA-2015-

00073), albeit occurring earlier. DOE concluded that the change in grout formula to one with 

enhanced reductive capacity but decreased compressive strength and increased hydraulic 

conductivity at the top of the Tank 16H primary and annulus would not impact compliance with 

HTF performance objectives.

SRR-CWDA-2015-00159. “Tank 16 Final Configuration Report for H-Tank Farm at the 

Savannah River Site.” Revision 1. Aiken, South Carolina: Savannah River Remediation, LLC. 

May 2016.

This report documented data obtained from the grouting of Tank 16H and clarified exceptions 

that occurred relative to the intended configuration described in the closure module 

(SRR-CWDA-2013-00091). Data presented included grouting operation dates, average 28-day 

compressive strength test results obtained from tank grout (but not from clean cap grout) test 

cylinders, bleedwater test results, and bulk plus clean cap grout fill, cooling coil grout fill, and 

equipment grout fill volume actuals versus estimates. The report also described three cooling 

coils that were not completely filled with coil grout, and documented a change in configuration 

related to use of clean cap grout to complete filling the void space at the top of the primary and 

annulus after bulk fill tank grout exhibited significant mound development beneath active risers. 

Due to discrepancies in the closure module description, the report also clarified the nature of 

equipment remaining in Tank 16H that was filled with grout.

DOE reported average compressive strength test results from a total of 272 ASTM C39 test 

cylinders. The 28-day post-casting compressive strength average was 2,788 psi (192 bars). 

DOE also reported that the volume of reducing grout to be placed inside the primary was 

estimated at 5,552 cubic yards (4,245 cubic meters), while the actual volume of reducing grout 

placed in the primary was 5,425 cubic yards (4,148 cubic meters), which is 97.7 percent of the 

estimate. Likewise, the estimated volume of reducing grout required to fill the annulus was 

687 cubic yards (525 cubic meters) compared to an actual volume placed of 697 cubic yards 

(533 cubic meters). Finally, 21 cubic yards (16.1 cubic meters) of reducing grout were 

estimated as needed to fill Tank 16H risers, whereas 23 cubic yards (17.6 cubic meters) were 

placed.
- 49 -

SRR-CWDA-2015-00160. “Evaluation of the Performance Assessment Impact of using an 

Alternative Fill Grout in the H-Area Tank Farm (Interoffice Memorandum to G.C. Arthur from 

M.H. Layton).” Revision 0. Aiken, South Carolina: Savannah River Remediation, LLC. 

January 4, 2016.

This interoffice memorandum evaluated the impact to meeting HTF performance objectives 

(SRR-CWDA-2010-00128) of using more flowable clean cap grout (C-SPP-Z-00012) to 

complete filling certain tanks in the HTF (e.g., Tank 16H) rather than tank grout. The HTF PA 

contains assumptions about the performance of tank-filling grout with respect to (i) its chemical 

properties, (ii) waste tank stability, (iii) inadvertent intruder prevention, and (iv) flow modeling. 

Use of clean cap grout should not decrease the overall reductive capacity of the grout fill 

because clean cap grout contains substantially greater weight percent slag than does tank grout 

[i.e., 45 wt% slag per C-SPP-Z-00012 (Revision 1) compared to approximately 30 wt% slag per 

C-SPP-F-00055 (Revision 4)]. Use of clean cap grout is not expected to decrease waste tank 

stability or provide any less a physical barrier to intruders because tested cylinders of Vault 4 

(now known as Saltstone Disposal Unit 4) clean cap grout prepared with Grade 100 slag 

cement yielded compressive strengths >5000 psi (>345 bar) when tested after more than 

500 days of hydration. The average compressive strength of four Vault 4 test cylinders 

(2014-07V1JE4002-0002; 2014-07V1JE4002-0003) was 6202 psi (428 bar), but the memo 

notes that any clean cap grout that might be prepared for future use in HTF tank closure would 

use Grade 120 slag cement rather than Grade 100 slag that had been used in Tank 16H, which 

potentially would further improve its compressive strength. Use of clean cap grout is not 

expected to increase the overall hydraulic conductivity of the grout fill or invalidate related flow 

modeling assumptions because three tested cylinders of Vault 4 clean cap grout prepared with 

Grade 100 slag cement yielded an average saturated hydraulic conductivity of 2.2 × 10−9 cm/s

(Amec Foster Wheeler, 2015), compared to the slightly lower value of 2.1 × 10−9 cm/s assumed 

in the HTF PA. Given that any clean cap grout that might be prepared for future use in tank 

closure would be batched using Grade 120 slag cement, the hydraulic conductivity of that grout 

fill would likely be lower. The memo concludes that use of clean cap grout (C-SPP-Z-00012) 

during HTF tank closures can be executed while yet in compliance with the HTF performance 

objectives (SRR-CWDA-2010-00128).

SRR-LWE-2014-00013. Walters, C.D. “Tank 16H Grout Strategy.” Revision 1. 

Aiken, South Carolina: Savannah River Remediation, LLC. January 6, 2015.

This planning document described DOE’s intended strategy for grouting Tank 16H, including 

grout functions, requirements and formulation (C-SPP-F-00055, Revision 4, Attachment 5.5), 

pour methodology, in-tank equipment, preferred grout-discharge risers, intended ventilation 

risers, video-camera-based inspections, cooling coil flushing, and tank, annulus, equipment, 

cooling coil, and riser grouting sequences. DOE’s Tank 16H grouting strategy was revised as 

grouting operations occurred, as reported in the final configuration report (SRR-CWDA-2015-

00159), including required adjustments and configuration changes based upon field conditions 

and tank inspections.

For pour methodology, the grout strategy document stated that “Lessons learned from previous 

tank closures identified the benefit of a minimal time gap between grout trucks during select lifts 

in the annulus and the primary tank.” It is unclear what “select lifts” DOE is referring to (e.g., lifts 

associated with ventilation duct grouting). This report indicates that the grout delivery contract 

did not specify a required grout delivery frequency or a minimum number of cement trucks in 
- 50 -

rotation. DOE stated that while that the optimal number of grout trucks in rotation varies from 

one tank to another due to route length and personnel interaction, ideally there should be 8–10 

cement trucks in rotation.

DOE planned to place tank grout in the Tank 16H annulus and inside its ventilation duct. 

DOE stated that because the duct was already suitably supported, placing an initial bed of grout 

to provide support to the duct was unnecessary. The ductwork was said to contain numerous 

holes with the implication being that the grout could enter the duct through the holes. 

Additionally, the duct work contained waste material that DOE indicated could lead to plugging 

of the duct if grout were placed through the pants legs directly into the duct. The horizontal 

portion of the ventilation duct was to be filled with grout that entered it from above through open 

registers in its top surface and from below through various openings caused by degradation of 

the ductwork (ADAMS Accession No. ML16167A237). The vertical portions of the ventilation 

duct (“pant legs” or ventilation riser inlet/outlet) were filled to grade level with tank grout (not 

clean cap grout), but only after the rest of the annulus, including Lift 6, had been filled with tank 

and clean cap grout (ADAMS Accession No. ML16167A237). The Tank 16H procedure 

contrasts with all other duct grouting operations to date, including those later conducted for 

Tank 12H, which involved preliminary filling of the horizontal duct by directing grout into and 

through the vertical pant legs. The Tank 16H duct-grouting procedure assumed that there was 

no danger of the vertical duct being crushed from external pressure applied by grout fill in the 

annulus; therefore, the vertical duct was filled last, after all annulus lifts had been placed 

(ADAMS Accession No. ML16167A237).

Open equipment was to be filled with equipment grout only after any low-level openings were 

visually determined to be encased in tank grout. Vertically oriented cooling coils in the tank

primary require that structural support be provided by an external bed of tank grout to help 

prevent their failure and or roof collapse during internal grouting. This report called for exercise 

of engineering judgement to limit the external level of supporting tank grout to the minimum 

necessary that would provide support to the cooling coils while maximizing the potential for 

guillotined or severed coils to vent. Guillotined coils were to be grouted simultaneously from 

each end until full, with any residual flushwater remaining pocketed inside the coil. Any 

guillotined coils not connected to coil inlets or outlets would not directly receive cooling coil 

grout, and could only be passively filled with tank grout to some extent, thereby potentially 

leaving empty pore space within. The Tank 16H grout strategy specified that intact cooling coils 

containing chromate water should be flushed with one pore volume of water immediately prior to

initiating internal grouting to ensure a uniformly wetted path exists for grout to follow. In 

contrast, the Tanks 5F and 6F lessons learned document (SRR-CWDA-2014-00015) had 

recommended triple rinsing of cooling coils in the future, including those of Tanks 16H and 12H. 

The Tank 16H grout strategy called for flushwater (and later grout) to be collected at each coil

outlet in a tote or disposed of in another waste tank. After cooling coil grout was visually 

detected at each outlet, additional grout was to be introduced to ensure complete filling. Finally, 

the strategy document indicated that 12 primary tank and 18 annulus risers were slated to be 

filled with tank grout (cf. SRR-CWDA-2015-00159) up to the level of the riser opening, generally 

above grade level.
- 51 -

SRR-LWE-2014-000150. Ostler, M. “Tank 16-H Closure Assurance Plan.” Revision 0. 

Aiken, South Carolina: Savannah River Remediation, LLC. March 2015.

This planning document identified process requirements from the Tier 1 and Tier 2 closure 

documentation and provided a strategy (and checklist) to ensure that requirements were met 

and that required grouting operation documentation (including various surveillances, batch 

tickets, grout testing, and grouting operation video) was generated and archived during 

stabilization of residual waste (i.e., during grouting operations). The plan was a tool for SRR 

to ensure that Tank 16H was closed successfully, having met all regulatory process and 

documentation requirements. The plan stated that the grout testing laboratory qualification must 

be documented and that DOE should verify that the SRR Testing Laboratory performed grout 

testing per ASTM standards listed in Attachment 5.3 of the grout procurement specification

(C-SPP-F-00055, Revision 4). The planning document also stated that any changes to the 

initially qualified tank grout formulation (C-SPP-F-00055, Revision 4, Attachment 5.5) must be 

evaluated for impact to qualification and to previous SRNL testing. If re-qualification was not 

required, then an evaluation and justification should be provided by SRR Closure Engineering in 

either a technical report or a waste management question evaluation (e.g., SRR-CWDA-2015-

00100). The plan stated that any non-conformances should be documented.

SRR-LWP-2014-00049. Sareen, H. “SRR Subcontractor Surveillance Plan Furnishing and 

Delivery of Tank Closure Grout (TK 16) (P.O. No. SRRA-064184-1).” Revision 0. 

Aiken, South Carolina: Savannah River Remediation, LLC. June 1, 2015. 

This document described the method that SRR Construction Quality Services would use for

performing oversight of the subcontractor during furnishing and delivery of tank grout for

Tank 16H. The plan outlined the tank grout quality control surveillance and quality assurance 

assessments to be performed, and inspection records and checklists to be generated. 

This document did not anticipate use of clean cap grout in the Tank 16H primary and annulus.

SRR-TCR-2015-00024. “Tank 16 Grouting Lessons Learned (Interoffice Memorandum from 

B. Davis to L. Blackford and J. Williams).” Revision 0. Aiken, South Carolina: Savannah River 

Remediation, LLC. January 27, 2016.

This report documented lessons learned from Tank 16H grout and tank preparation and 

grouting operations, as well as recommendations for future operations including: (i) to reduce 

plugging of slick lines with grout, remove diversion valves and use removable spool pieces to 

route grout to tank fill points; (ii) to significantly reduce hazards to workers and work stoppages, 

eliminate decant totes and grout intact coils directly to a waste tote, especially when only a few 

intact coils are to be grouted; (iii) to allow use of flowable clean cap grout to complete tank 

grouting in potential future cases where significant mounding of tank grout occurs, complete all 

necessary reviews, evaluations and testing in advance; (iv) to enable use of less restrictive 

grout placement or lift thicknesses, provide actual grout properties (specific gravity, set time, 

etc.) rather than bounding values to the structural department for use in their calculations; (v) to 

significantly reduce hazards to workers, evaluate the potential to eliminate (or modify) cooling 

coil grouting; (vi) to significantly reduce related work stoppages, conduct both failed and intact 

cooling coil grouting practice dry runs when all equipment and hoses are in place; (vii) to 

maintain lubrication of the slick line, evaluate use of additional pigs or other methods; 

(viii) determine a reasonable or acceptable range for bleed water exuded by tank grout by 

analyzing data from Tank 16H grout testing; (ix) anticipate seasonal weather conditions that will 
- 52 -

effect planned grouting operations and make appropriate preparations in advance (weather 

related contingency for slicklines, i.e., hot weather vs. cold weather); (x) to reduce set up costs, 

resource use, process time and risks, develop a method to flush cooling coils immediately 

followed by grouting of same (flushing and grouting has been conducted as two separate 

processes to date).

Finally, DOE and SCDHEC entered into an agreement that clean cap grout would not be used 

to cap Tank 12H without their express and prior approval. Therefore, DOE is to be notified as 

soon as mounding or pluggage issues occur that may later warrant use of clean cap grout so 

that they can immediately notify SCDHEC. It was recommended in the lessons learned 

document that associated requirements be included in the Tank 12H grout strategy document, 

communications plan, grouting work packages, and job briefings.

Work Order No. 01324150-64. Fail, J.A. “TK Clos & Reg Cn to Perform Grout Prep/Grout 

Placement TK 16.” Revision 0. Aiken, South Carolina: Savannah River National Laboratory. 

August 22, 2014.

This work order provided detailed lists of activities to be performed during grouting of Tank 16H. 

The order called for six grout placements (HTF-SKM-2014-00031, Grout Placement Plan) to be 

poured through tremies in multiple risers in the primary and annulus with a maximum drop 

height of 5 ft (1.5 m), as well as riser placements. The work orders included safety precautions 

and limitations that were to be followed (including radiation control procedures) during grouting.
- 53 -

Review Summaries of Tank 12H Documents:

LWO-LWQ-2016-00001. Thompson, J.W. “SRR Subcontractor Surveillance Plan Furnishing 

and Delivery of Tank Closure Grout (TK 12) (P.O. No. SRRA-064184-1).” Revision 0. 

Aiken, South Carolina: Savannah River Remediation, LLC. January 13, 2016.

This document described the method that SRR Construction Quality Services would use for

performing oversight of the subcontractor during furnishing and delivery of tank grout 

(C-SPP-F-00055) and clean cap grout (C-SPP-Z-00012) for Tank 12H. The plan outlined the 

grout quality control surveillance and quality assurance assessments to be performed, and 

inspection records and checklists to be generated.

SRR-CWDA-2014-00086. “Industrial Wastewater Closure Module for Liquid Waste Tank 12H, 

H-Area Tank Farm, Savannah River Site.” Revision 0. Aiken, South Carolina: Savannah River 

Remediation, LLC. May 2015.

This report is one of the key Tier 2 closure documents for Tank 12H that supports Tier 2 

Closure Authorization, which is DOE-SR’s final authorization to proceed with permanent 

stabilization of the waste tank system. Section 7.3 of this closure module described anticipated 

Tank 12H grouting operations, and suggested that grouting of the annulus ventilation duct 

may require an unspecified grout more flowable than tank grout. Notably, Section 7.3.2 of the 

document indicated awareness of a potential need to provide access points into the waste 

tank to address bleed water build-up. Grouting plans described by the closure module were 

summaries of more detailed information contained in the “Tank 12H Grout Strategy” 

(SRR-LWE-2014-00147) document; therefore, the reader is referred to the in-depth summary 

of the Tank 12H grout strategy for information on planned Tank 12H grouting operations.

SRR-CWDA-2015-00057. “Evaluation of the Use of Grade 120 Slag Cement in Tank Closure 

Grout versus Performance Assessment Assumptions (Interoffice Memorandum to G.C. Arthur 

from M.H. Layton).” Revision 1. Aiken, South Carolina: Savannah River Remediation, LLC. 

August 27, 2015.

This interoffice memorandum was included as a supporting reference to SRR-CWDA-2015-

00088. The memo documents DOE’s evaluation of the impact of switching from use of ground 

granulated blast furnace slag cement Grade 100 to Grade 120 (cf. ASTM C989) in the tank 

grout formulation. Section 3.2.3.3 of the tank grout procurement specification (C-SPP-F-00055, 

Revision 4; see also Attachment 5.5) specified that only Grade 100 slag cement should be used

in the mix. However, DOE staff defended the position that allowing use of Grade 120 slag in 

place of Grade 100 would not result in a tank grout mix incapable of meeting PA assumptions, 

would be consistent with the inputs and assumptions of the PAs, and could be carried out in 

compliance with performance objectives assuming other grout performance and testing 

requirements were met.

Blast furnace slag is a byproduct of the iron and steel industry that is finely ground and

marketed as a partial substitute for Portland cement. The particle size distribution of slag is 

generally finer than or similar to that of Portland cement (WSRC-TR-2001-00359). 

Major components are oxides of silicon, aluminum, calcium, and magnesium; minor

components include compounds containing manganese, iron, and sulfur (SRNL-PSE-2007-

00282, Table 1). Elemental composition varies slightly depending on source material and 
- 54 -

additives used in iron or steel production. The reductive capacity of slag is relatively insensitive 

to its chemical composition (PNNL-22977/EMSP-RPT-015, Table 3.1). The FTF and HTF PAs 

(SRS-REG-2007-00002 and SRR-CWDA-2010-00128) each contained assumptions about the 

reductive capacity of tank grout. The quantity of slag used in tank grout was specified to 

produce desirable chemistry and extend the reductive capacity timeline. Slag grade and 

associated physical properties (i.e., particle size distribution and activity index) do not impact 

reductive capacity (VSL-15R3740-1, Table 5.5); therefore, use of a carefully selected Grade 120 

slag in tank grout, such as Lehigh Hanson or Lafarge, would not violate PA assumptions about 

its chemical properties. For example, compared to the lower reductive capacity (i.e., 722 μeq/g) 

of the Holcim, Inc. Grade 100 slag that was originally used in tank grout, reductive capacities of 

Lehigh Hanson (preferred) and Lafarge (optional) Grade 120 slags are 812 μeq/g and 

740 μeq/g, respectively (VSL-15R3740-1, Table 5.5). Switching to use of either one of these 

slags would therefore preserve or enhance the desirable chemical properties (i.e., reductive 

capacity) of any cementitious grouts that these slags are used in.

The Tank Farm PAs also assume that tank grout has adequate compressive strength 

[i.e., minimum of 2000 psi (138 bars) at 28 days post-placement, per FTF Table 3.2-4 and 

HTF Table 3.2-9] to withstand the overburden load on the tank at closure. Slag grade does not 

negatively impact waste tank stability because tank grout will still be required to achieve the

minimum 28-day compressive strength of 2000 psi (138 bars). Testing performed on tank grout 

using Grade 120 slag has an average 28-day compressive strength of 2180 psi (150 bars), 

exceeding the minimum PA requirement (SDDR No. 13182).

Finally, the Tank Farm PA flow modeling assumed tank grout material properties (FTF PA 

Section 4.2.3.2.3 and HTF PA Section 4.2.2.2.4) that would limit infiltration of water to the 

contamination zone at the bottom of the tank. The tank grout formulation was developed to 

meet assumed material properties, with conformance to the grout formulation validated through 

adherence to tank grout specification requirements (C-SPP-F-00055). DOE staff maintain that 

use of Grade 120 slag in tank grout, while not relaxing other tank grout specification testing and 

performance requirements (e.g., flowability, weight of grout ingredients such as cement, sand, 

water, fly ash, slag, etc.), will not negatively impact the grout material functionality with regards 

to water flow and diffusion, because the hydraulic conductivity of tank grout will not be impacted 

by the change in slag grade.

SRR-CWDA-2015-00088. Layton, M.H. “Unreviewed Waste Management Question Evaluation 

– Use of Grade 120 Slag in Tank Closure Grout.” Revision 0. Aiken, South Carolina: 

Savannah River Remediation, LLC. September 2015.

This form described a proposed action and evaluation of the action to use ground granulated 

blast furnace slag cement Grade 120 in place of Grade 100 in the waste tank grout formulation. 

Specifically, a deviation (SDDR No. 13182) from Section 3.2.3.3 of the tank grout procurement 

specification (C-SPP-F-00055), which currently requires use of Grade 100, was proposed to 

allow either grade to be used. To examine the impact of this action, DOE undertook an 

evaluation of the potential to meet tank closure performance objectives using Grade 120 instead 

of Grade 100 slag (SRR-CWDA-2015-00057). DOE indicated that use of Grade 120 as an 

alternative to Grade 100 would be consistent with the inputs and assumptions contained in the 

Tank Farm PAs (SRS-REG-2007-00002 and SRR-CWDA-2010-00128), and also stated that 

because the FTF and HTF WD Basis Documents (DOE/SRS-WD-2012-001 and DOE/SRS-WD2014-001) do not prescribe a grout formulation but only describe general grout properties, the 
- 55 -

proposed action was within the bounds of the WD Basis Documents. The justification indicated 

that because the proposed action would not relax other grout specification requirements and 

tank grout would continue to perform as assumed in the Tank Farm PAs, the action would not 

impact compliance with performance objectives.

SRR-LWE-2012-00030. “Tank 12 Cooling Coil Flushing Strategy (Interoffice Memorandum to 

M.D. Buxton from S.J. Worthy and J.R. Tihey).” Revision 1. Aiken, South Carolina: Savannah 

River Remediation, LLC. November 28, 2012.

This interoffice memorandum documented DOE’s guillotined and broken cooling coil 

decontamination and flushing strategy that would be employed to remove residual 

contamination from Tank 12H. Exterior contamination was to be removed from all cooling coils 

during mechanical mixing, oxalic acid cleaning, and water wash campaigns. Twenty-seven 

failed vertical coils and one failed horizontal coil were to be flushed from both sides (supply and

return) simultaneously with H-Area well water; flushwater was to drain through coil leak sites 

into the tank. DOE estimated vertical and horizontal cooling coil volumes as approximately 

454 and 625 L (120 and 165 gal), respectively, and that the flushwater volume added to the 

primary tank would exceed 11,000 L (3000 gal). The memo did not describe the flushing 

strategy for eight intact cooling coils in Tank 12H, indicating instead that flushing of these coils 

would occur only during the grouting phase.

SRR-LWE-2014-00147. Chandler, T. “Tank 12H Grout Strategy.” Revision 1. 

Aiken, South Carolina: Savannah River Remediation, LLC. August 31, 2015.

This planning document described DOE’s intended strategy for grouting Tank 12H, including 

grout functions, requirements and formulation, pour methodology, in-tank equipment, preferred 

grout-discharge risers, intended ventilation risers, video-camera-based inspections, cooling 

coil flushing, and tank, annulus, equipment, cooling coil, and riser grouting sequences. 

DOE’s Tank 12H grouting strategy may have been revised as grouting operations occurred and 

the final grouted tank configuration will be reported in the final configuration report, including

any required adjustments and configuration changes based upon field conditions and detailed 

inspections. As with Tank 16H, the grout delivery contract for Tank 12H did not specify a

required tank grout delivery frequency or minimum number of trucks in rotation. In this 

document, DOE clarified that the ideal grout delivery frequency is thought to be 8 to 10 trucks 

per hour. This differed from the Tank 16H Grout Strategy document, which had suggested that 

there should be 8 to 10 cement trucks in rotation.

DOE planned to place tank grout in the Tank 12H annulus and its ventilation duct. Grout was 

to be placed in the annulus between the outside radius of the ventilation duct and the annulus 

steel pan. Unlike the strategy used to grout Tank 16H, an approximately 6-to-12-in (15-to30-cm)-deep grout layer was to be placed on the annulus pan floor to support the horizontal 

ductwork during grouting. The horizontal part of the duct was then to be filled by placing grout 

directly into the vertical inlet piping system (“pant legs” or ventilation riser inlet/outlet) until grout 

was observed to exit the horizontal ductwork through its register openings. As the annulus 

grout level was raised, grout was to flow through any remaining register openings into any 

unfilled portions of the horizontal ductwork. SRR-LWE-2014-00147 indicates both of the 

following for Tank 12H: (1) vertical portions of the duct were to be filled after completion of the 

annulus bulk fill, and (2) to lessen the potential for duct collapse, the vertical section of the 

ventilation inlet duct will be filled with grout to grade level in parallel with bulk filling of the 
- 56 -

annulus17. It is unclear which statement was intended. The annulus exhaust riser was to be 

grouted to grade level after the grout level in the annulus reached the bottom of the riser. 

Because DOE anticipated that groundwater intrusion into the annulus could be a problem, a 

temporary water removal system was installed (SRR-LWE-2015-00048) to transfer any water in 

the annulus into Tank 10H prior to grouting. DOE expected water levels in the annulus could be 

reduced to no more than 2 in (5 cm) by this water removal system. If necessary, DOE was also 

prepared to remove accumulated water from the annulus into decant totes after annulus 

grouting had begun.

To alleviate mounding beneath the tremie, the Tank 12H grout strategy report identified 

distribution pipe mobility within risers as a means to allow some limited directional control of 

discharging grout. The report also allowed for potential elimination of the tremie based on grout 

freefall experimental results obtained during grout drop testing (RPT-5539-EG-0016), which 

indicated that grout properties would not be adversely affected by freefall. Also based on grout 

drop test results (i.e., Test 2), DOE indicated that they planned to avoid placing grout directly 

into wet areas of the tank because doing so could enhance bleed water segregation.

Open equipment was to be filled with equipment grout only after any low-level openings were 

visually determined to be encased in tank grout. Vertically oriented cooling coils in the tank 

primary require structural support be provided by an external bed of tank grout to help prevent 

their failure and or roof collapse during internal grouting. This report called for the exercise of 

engineering judgement to limit the external level of supporting tank grout to the minimum 

necessary that would provide support to the cooling coils while maximizing the potential for 

guillotined or severed coils to vent. Twenty-eight (28) of thirty-six (36) cooling coils in Tank 12H 

had failed prior to commencing grouting operations, and were flushed previously (SRR-LWE2012-00030). Guillotined coils were to be grouted simultaneously from each end until full, with 

any residual flushwater remaining pocketed inside the coil. Any guillotined coils not connected 

to coil inlets or outlets would not directly receive cooling coil grout, and could only be passively 

filled to some extent with tank grout. The report indicated that intact cooling coils containing 

chromate water would be flushed with water. The Tank 12H grout strategy did not discuss 

disposal of chromate-laden flushwater in any detail, instead referring to a related work order that

would be developed. The strategy document also did not discuss how DOE would ensure 

complete filling of any remaining intact cooling coils. Rather, the report described how DOE 

would test the eight remaining cooling coils to determine if they remained intact or had also 

failed. Nine primary tank and six annulus risers were slated to be filled with tank grout up to the 

level of the riser opening, generally above grade level.

SRR-LWE-2014-00161. Walters, C.D. “Tank 12 Internal Equipment Evaluation.” Revision 0. 

Aiken, South Carolina: Savannah River Remediation, LLC. February 12, 2015.

This report describes equipment (and inventory) left in the Tank 12 primary and annulus that will 

be grouted in place after cleaning operations. Two sampling crawlers were abandoned inside 

the primary, one near Riser 6, and the other northeast of the center column. Riser 6 contains 

an abandoned transfer jet and pump. Riser 7 contains a submersible transfer pump and a 

 17 SRR-LWE-2015-00048 indicates the vertical section of the annulus inlet duct was to be filled with cooling coil 

grout (not tank grout) during Placements 5, 7, and 9, whereas the annulus exhaust piping was to be filled during 

riser placements near the end of grouting operations. 
- 57 -

caisson with thermowell. The North riser contains an annulus transfer jet. The equipment 

remaining in Tank 12 contains insignificant inventory estimated at a volume of 46.6 L (12.3 gal).

SRR-LWE-2015-00032. Ostler, M. “Tank 12-H Closure Assurance Plan.” Revision 0. 

Aiken, South Carolina: Savannah River Remediation, LLC. April 2015.

This planning document identified process requirements from the Tier 1 and Tier 2 closure 

documentation and provided a strategy to ensure that requirements were met and that required 

documentation (including various surveillances, batch tickets, grout testing, and grouting 

operation video) was generated and archived during stabilization of residual waste (i.e., during 

grouting operations). The plan was a tool for SRR to ensure that Tank 12H was closed 

successfully, having met all regulatory process and documentation requirements. The plan 

stated that the grout testing laboratory qualification must be documented and that DOE should 

verify that the SRR Testing Laboratory performed grout testing per ASTM standards listed in 

Attachment 5.3 of the grout procurement specification (C-SPP-F-00055, Revision 4). 

The planning document also stated that any changes to the initially qualified tank 

grout formulation must be evaluated for impact to qualification and to previous SRNL testing. 

This document indicated that the tank grout formulation to be placed into Tank 12H could 

exercise the option to use Grade 120 slag cement, whereas Grade 100 had been used during 

prior tank grouting operations. If re-qualification was not required, then an evaluation and 

justification should be provided by SRR Closure Engineering in either a technical report or a 

waste management question evaluation. The plan stated that any non-conformances should be 

documented. 

SRR-LWE-2015-00048. Griffin, A.L. “Path Forward for Tank 12 Annulus Liquid Removal 

(Interoffice Memorandum to E. Patten et al. from A.L. Griffin and G.C. Arthur).” 

Aiken, South Carolina: Savannah River Remediation, LLC. Revision 0. July 7, 2015.

This interoffice memorandum provided DOE’s path forward on removal of water from the 

Tank 12H annulus (as a non-waste transfer), prior to initiation of grouting. Tank 12H has a 

history of groundwater intrusion. Removal of groundwater was necessitated when an 

unanticipated water level of approximately 28 cm (11 in) was identified during video inspection 

of the annulus on May 16, 2015. Subsequently, video inspection frequency of the Tank 12H

annulus was increased to daily on May 20, 2015. The annulus liquid sampled on May 21, 2015 

(Attachment 1) had low-level contamination, and therefore was classified as non-waste. 

The recommended path forward was to transfer intruded groundwater out of the Tank 12H

annulus and into adjacent Tank 10H. To promote annulus drying, supplementary ventilation 

was installed and operated. It was also recommended that the equipment required to pump 

groundwater out of the annulus be installed as a temporary modification.

Work Order No. 01337683-33. Patton, G.W. “Placement of Bulk Fill Grout: Tank 12.” 

Revision 0. Aiken, South Carolina: Savannah River National Laboratory. April 29, 2015.

This work order provided detailed lists of activities to be performed during grouting of Tank 12H. 

The order called for nine grout placements (HTF-SKM-2015-00021, Grout Placement Plan) to 

be poured through tremies in multiple risers in the primary and annulus with a maximum drop 

height of 10 ft (3 m), as well as multiple riser placements. The work orders included safety 

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

during grouting. Note that this is the first tank closure work order for which the maximum drop 
- 58 -

height was increased to greater than 5 ft (1.5 m). Placement 3 involved grouting of the 

horizontal section of the ventilation duct. A tremie was to be installed in the annulus inlet to fill 

the horizontal ventilation duct to the point at which grout was observed exiting the “horizontal 

ducting distribution holes”. The vertical section of the annulus inlet duct was to be filled with 

cooling coil grout (not tank grout) during Placements 5, 7, and 9, whereas the annulus exhaust 

piping was to be filled during riser placements near the end of grouting operations. If workers 

observed water in risers, they were to add dry grout per guidance of SRR-CWDA-2012-00051, 

Revision 2.
- 59 -

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March 2014.

SRR-CWDA-2014-00020. Martin, B. “Tanks 5 and 6 Final Configuration Report for F-Tank

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

Remediation, LLC. July 2014.

SRR-CWDA-2014-00026. “Requested Pre-Visit Information in Support of U.S. Nuclear

Regulatory Commission F-Tank Farm March 2014 Onsite Observation Visit (Attachment 4 of 

Letter to Sherri R. Ross from Steven A. Thomas).” Revision 0. Aiken, South Carolina: 

Savannah River Remediation, LLC. March 13, 2014.

SRR-CWDA-2014-00020, Martin, B. “Tanks 5 and 6 Final Configuration Report for F-Tank

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

Remediation, LLC. July, 2014.
- 64 -

SRR-CWDA-2014-00029. “Savannah River Site F-Tank Farm NRC Onsite Observation Visit: 

March 26 & 27, 2014 (Presentation).” Revision 1. Aiken, South Carolina: Savannah River 

Remediation, LLC. March 2014.

SRR-CWDA-2014-00086. “Industrial Wastewater Closure Module for Liquid Waste Tank 12H, 

H-Area Tank Farm, Savannah River Site.” Revision 0. Aiken, South Carolina: Savannah River 

Remediation, LLC. May 2015.

SRR-CWDA-2015-00073. “Tank 12 Special Analysis for the Performance Assessment for the 

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

Remediation, LLC. August 2015.

SRR-CWDA-2015-00095. “Savannah River Site F and H Area Tank Farms NRC Onsite

Observation Visit, July 28–29, 2015.” Revision 1. Aiken, South Carolina: Savannah River

Remediation, LLC. August 2015.

SRR-CWDA-2015-00109. Rush, J. “DOE/SRR Liquid Waste Operations Quarterly FFA 

Update—Tank 16 Grouting Update” (Presentation). Revision 0. Aiken, South Carolina: 

Savannah River Remediation, LLC. August 19, 2015.

SRR-CWDA-2015-00170. “Action Item Follow-Up in Support of U.S. Nuclear Regulatory 

Commission Onsite Observation Visit on July 28–29, 2015” (Letter to Sherri R. Ross from 

Steven A. Thomas). Revision 0. Aiken, South Carolina: Savannah River Remediation, LLC. 

December 15, 2015.

SRR-CWDA-2016-00031. “Action Item Follow-Up in Support of U.S. Nuclear Regulatory

Commission Onsite Observation Visit on February 2–3, 2016.” (Letter to Sherri R. Ross from 

Steven A. Thomas). Revision 0. March 22, 2016.

SRS-REG-2007-00002. “Performance Assessment for the F-Tank Farm at the Savannah River 

Site.” Revision 1. Aiken, South Carolina: Savannah River Remediation, LLC. March 31, 2010.

Topçu, İ.B. and V.B. Elgün. “Influence of Concrete Properties on Bleeding and Evaporation.” 

Cement and Concrete Research. Vol. 34, p. 275–281. 2004.

U-ESR-H-00113. Clark, J.L. “Tank 16 Final Residual Solids Determination and Uncertainty 

Estimate.” Revision 0. Aiken, South Carolina: Savannah River Remediation, LLC. 

November 2013.

VSL-14R3330-1. “Saltstone Clean Cap Grout Assessment.” Revision 0. Columbia, Maryland:

Vitreous State Laboratory (EnergySolutions, Federal EPC, Inc.). March 2014.

W163389. Whaley, J.H. “Savannah River Plant 200 Area Add. Waste Storage Tanks Building 

No. 241-H Dehumidification System Heating & Ventilation (U).” Drawing No. M-MD-H-7643,

Revision 26. Aiken, South Carolina: Savannah River Site. August 15, [sic] 2055.

Walter, G.R. and D.M. Necsoiu. “Tank Grout Water Conditioning Tests (Status Report).”

San Antonio, Texas: Center for Nuclear Waste Regulatory Analyses. September 2015.
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Wainwright, P.J. and H. Ait-Aider. “The Influence of Cement Source and Slag Additions on the

Bleeding of Concrete.” Cement and Concrete Research, Vol. 25, No. 7, p. 1445–1456. 1995.

WSRC-STI-2007-00544. Denham, M.E. “Conceptual Model of Waste Release from the

Contaminated Zone of Closed Radioactive Waste Tanks.” Revision 2. Aiken, South Carolina:

Savannah River Site. 2007.

WSRC-TR-2001-00359. Langton, C.A., et al. “State of the Art Report on High-Level

Waste Tank Closure.” Revision 0. Aiken, South Carolina: Savannah River Site. July 2001.
- 66 -

Attachment 1

SRR-CWDA-2015-00170 transmitted more than 40 DVDs of Tank 16H grouting operation video. 

This attachment provides a description of horizontal ductwork grouting in the annulus of 

Tank 16H, which occurred on June 11, 2015. During the early minutes of annulus grouting that 

day (11:33 am+), the West Riser video camera pointed straight down rather than to where it 

could have observed grout directly entering nearby ventilation duct register(s). By the time the 

camera panned downstream (11:36 am), any nearby duct(s) were covered with grout and no 

longer visible. It is unknown the extent to which the ventilation duct is fully filled with grout.

At 12:18 pm, the East Riser video camera first glimpsed stagnant, non-flowing grout already at 

rest inside the horizontal duct via a register in its field of view. A few minutes later (12:21 pm), 

fresh grout was observed flowing inside the duct as viewed through this register (Figure A-1A). 

Upstream, the duct was not completely full of grout; flow in the duct was under open channel 

conditions, not conduit flow/plug flow conditions. By 12:23 pm, grout had ceased flowing 

through the duct. Subsequent truckloads of grout did not continue to fill the interior of the duct 

(e.g., still stagnant at 12:42 pm) in this location until, as head in the annulus increased, a fresh 

batch sent grout flowing from above down into the partially filled duct via the register (Figure 

A-1B) observed by the East Riser camera (1:00 pm). Grout had been immobile and setting up 

inside the partially filled duct for almost 40 minutes before fresh grout entered this part of the 

duct again, this time from above. This new batch of fresh grout pouring into the open register 

may or may not have expired (i.e., truck emptied or discharge ceased) before the partially filled 

duct became completely filled up to that register location. Because grout placed earlier had 

been flowing in the duct under open channel conditions, some of the fresh grout filling the 

register from above had to reverse course and flow backward in the duct to backfill the 

remaining empty porosity. If the truckload of grout expired while filling was ongoing, empty 

space may be preserved inside the duct away from the register opening because hardening 

grout had now been placed around this register opening on all sides; additional truckloads of 

grout would not necessarily have been able to overcome the inertia of the setting grout. 

Meanwhile, on the other side of the East Riser camera’s field of view, it took until 12:52 pm 

for grout to be observed flowing inside the duct (as viewed from a register). The initial pulse 

of grout flowing inside the duct from this other direction stopped flowing by approximately 

12:54 pm. Then, 14 minutes later at 1:08 pm, grout flowing in the annulus from the original 

direction overtopped this register opening and flowed into that part of the duct from above.

Visual landmarks such as register openings disappeared beneath pulses of grout even while

inflow down into the register opening was likely still occurring. Cameras would pan away and 

then possibly return to view a register opening beneath flowing grout, but the most obvious 

visual cue (the register opening) was essentially buried such that subtle grout flow behaviors 

that may have indicated continued duct infilling were not easily interpreted. If visual guides for 

duct openings (perhaps a mark on the tank or vault walls above) had been present in the 

annulus of Tank 16H, DOE may have been better able to associate observed surficial grout 

flow behavior with the duct filling process.
- 67 -

Figure A-1. Still Shots of Grout Placement in the Annulus Duct of Tank 16H.
- 68 -

Attachment 2

Development of an Acoustic Emission Crack Signal Detection Technique for 

Waste Stabilizing Tank Grout

The U.S. Nuclear Regulatory Commission (NRC) previously sponsored studies at the Center for 

Nuclear Waste Regulatory Analyses (CNWRA®) to better understand the potential for cracks 

and other preferential pathways to form in tank grout monoliths during the early years after grout 

is placed. Results from this study indicated that grout monoliths may be at risk for multiple 

cracking regimes, particularly in the first 24 hours post-placement. The CNWRA is now 

providing technical assistance to the NRC to test the feasibility of using acoustic emission (AE) 

technology for passively monitoring crack formation within cementitious tank grout, including 

monitoring during the early stages of hydration when the cementitious materials are in a gel 

form and difficult to monitor acoustically. Using AE monitoring, it may be possible to record the 

timing and location of cracking and to map crack propagation throughout cementitious materials. 

Such data might be used to improve understanding of the mechanisms of crack development 

and distribution of cracks within the cementitious materials.

During fiscal year 2015, CNWRA staff performed a sequence of experiments to develop an 

understanding of the ultrasonic properties of tank grout and saltstone. The resulting property 

data were used to develop an AE monitoring technique capable of detecting and locating 

cracking events in the grout, which was demonstrated on a mesoscale specimen of tank grout 

during hydration. Ultrasonic experiments were performed using standard ultrasonic probes and 

driver instrumentation. Acoustic emission experiments were performed using a 16 channel 

Physical Acoustics Corporation DiSP Acoustic Emission Workstation, Model PCI–2 (i.e., an AE 

instrument). Two types of reducing tank grout and two types of non-radioactive saltstone were 

used to develop specimens for the experiments, where early experiments were conducted on 

proxy formulations, such as a specimen cored from the intermediate-scale grout monolith, until 

materials necessary to develop the LP#8 tank grout and saltstone formulas became available. 

All specimens contained Grade 100 ground granulated blast furnace slag cement.

Initial testing was performed on tall cylindrical specimens [70 mm (2.8 in) diameter and more 

than 200 mm (7.9 in) height] of both grout types to determine their ultrasonic properties in their 

hardened state. Ultrasonic through-transmission measurements were conducted using a 

variation of the method defined in Appendix X2 of ASTM E494. From these tests, tank grout 

was determined to have a nominal longitudinal wave speed of 4.14 mm/μs, a nominal shear 

wave speed of 2.9 mm/μs, and an approximate attenuation of 65–75 dB/m (20–23 dB/ft).

Saltstone (identical to clean cap grout except for the presence of additional salts) was 

determined to have a nominal longitudinal wave speed of 2.39 mm/μs, a nominal shear 

wave speed of 1.13 mm/μs, and an approximate attenuation of 80–100 dB/m (24–30 dB/ft). 

Both grout materials exhibited peak propagation amplitudes in the 100–150 kHz range and both 

materials permitted longitudinal wave signals to propagate with greater signal response than 

their shear wave counterparts.

The initial findings on the fully hardened specimens were used to define preliminary AE 

acquisition settings that could be tested on 1-to-2 L (1-to-2 qt) bench-top specimens. 

Investigations were conducted by installing various configurations of AE sensors on the 

specimens and then performing ASTM E976 Hsu Nielsen source tests (pencil lead breaks) at 

known locations around their surfaces. The recorded pencil lead break signals were used to 
- 69 -

evaluate and refine AE sensor arrangement, acquisition settings, and data processing logic 

used to locate signal sources. Through initial refinement of the AE monitoring technique on the 

bench-top specimens, a sensor arrangement capable of detecting and locating pencil break 

events with an average error of less than 26 mm (1 in; comparable to 1 wavelength) 

was selected.

An experiment was then performed to passively monitor the hydration process of a mesoscale, 

108-L (114-qt) specimen of tank grout from initial placement through the first full month of 

hydration and hardening. The intent of the experiment was to evaluate the detection sensitivity 

and location capability of the AE monitoring technique against artificial crack sources throughout 

the grout hardening process and to collect ultrasonic property data throughout the grout 

hydration process. Given past experience with specimens of similar size, significant natural 

cracks were not expected to form, so artificial signals were periodically introduced via pencil 

break tests performed across the top surface of the specimen. Over the 32-day monitoring 

period, the AE system detected artificial signals with increasing consistency and accuracy. 

In the first few days of testing, signal detection and source location were prevented by high 

attenuation in the gel-like grout, which severely limited the measurement of key ultrasonic 

property data. By the end of the test, the system was demonstrating 100 percent detection of 

pencil lead breaks and location accuracy of less than 12 mm (0.5 in) across the top surface of 

the specimen.

In light of the severe attenuation observed in the initial mesoscale AE monitoring experiment, 

an additional experiment was devised to measure wave speed and attenuation throughout 

the grout hydration process. The method relies on performing periodic automated 

through-transmission tests on two specimens of grout with two known thicknesses and on a 

reference of water, using their relative signal responses and times-of-flight to calculate 

attenuation and phase velocity at each stage in hydration. The group velocity data could then 

be derived from the phase velocity data. Initial testing was performed on LP#8 tank grout. 

Initial data indicate that there are two frequency bands conducive to AE monitoring—one in the 

100–150 kHz range and a second near 50 kHz. Although detailed analysis of the velocities in 

these frequency bands was prevented by experimental complications, the phase velocities at 

higher frequencies were successfully captured, and attenuation response was consistent with 

previous test observations.

In future work, additional testing is required to complete characterization of the ultrasonic 

properties of tank grout and saltstone. Once the remaining property data are measured, 

CNWRA staff can optimize the AE monitoring technique. If AE-based crack detection and 

location is proven successful at the mesoscale, then the monitoring approach could be further 

refined for implementation on waste tanks for detecting cracks that may affect the capability of 

tank grout and clean cap grout to provide a low-permeability reducing environment that limits 

release of key radionuclides.
- 70 -

Attachment 3

List of Outstanding References

Follow-up Action Items from the May 17, 2016, teleconference:

1. DOE indicated that they did not measure the accumulated volume of water at the top of 

Tanks 5F/6F that led to creation of a work order to remove water from the tank top prior to 

grouting the risers. The NRC indicated that they recall DOE reporting that about 12 inches of 

standing water was observed in one of the tank risers. DOE indicated that they may have 

pumped standing water out of one riser but they would need to go back and confirm the 

quantity of water pumped out of Tanks 5F/6F, if any.

2. DOE to provide follow-up information on how much water was pumped out of Tank 12H 

annulus and primary (DOE estimated about 1000 gallons was pumped out of the Tank 12H 

annulus).

3. DOE to provide information on the quantity of Slick Willie/water used in Tanks 18/19 as a 

pump priming agent and slick line lubricant (similar information was previously provided for 

Tanks 5F/6F but not for Tanks 18F/19F).

4. DOE will provide the grout formulation used for clean cap grout in Tank 16H (3 formulations 

were provided in procurement specification CSP-SPP-Z-00012 and it is not clear which was 

used). The design water-to-cement ratio listed on 2 batch tickets for clean cap grout was 0.5 

(but two formulations had 0.5 in CSP-SPP-Z-00012). DOE will also look at the batch tickets 

for clean cap grout that were provided to NRC (042239 and 042345) and clarify differences 

between the two batch tickets (one included the ingredient TEMPER in the mix and one did 

not). The NRC specifically asked DOE to clarify if caustic was used in the formulation (DOE 

did not think caustic was added because that would speed up the hydration reactions and 

cause the cement to be less flowable) and to clarify what the ingredient “TEMPER” is. DOE 

offered an on-the-spot description of “TEMPER” but may have some additional follow-up 

information that they can provide to the NRC.
- 71 -

Follow-up list of questions from the May 17, 2016, teleconference

The NRC provided DOE with a list of requested references via email on February 26, 2016, and 

updated the requested reference list via e-mail on March 30, 2016. Most of these references 

were provided to the NRC by DOE prior to the May 17, 2016, teleconference. Due to time 

constraints during the May 17, 2016, teleconference, the NRC was unable to ask a few 

questions related to the new reference reviews and other lingering questions. The NRC 

requests DOE to respond to the following questions via email or letter. Alternatively, interested 

parties could participate in a follow-up teleconference to discuss these questions, if preferable to 

DOE:

1. NRC requested the final specification for the clean cap grout as a follow-up action to the 

May 17, 2016, teleconference. Could DOE clarify how it achieves the minimum flowability 

given that SRNL-STI-2012-00558 indicates that flowability would be compromised at a 

water-to-cement ratio of 0.51, and that the one most-relevant sample tested in SRNL-STI2012-00558 (sample WP023 with a water-to-cement ratio of 0.51) had slump flow of only 

18.6 cm (7.5 in) and no sample had greater slump flow than 29 cm? Could DOE clarify if 

any Daratard or any admixtures were used in the Tank 16H clean cap specification, or if 

there is an option to use admixtures in the future?

2. Could DOE clarify why compressive strength measurements are not required for the clean 

cap grout? 

3. Could DOE provide reference VSL-14R3330-1, which provides test results for clean cap 

grout mixed at varying water-to-premix ratios and adding NaOH solution (measures total 

bleed, reabsorption time, flowability, and uniformity).

4. NRC requested and DOE provided Work Order Nos. 01324150-64 and 01337683-33. 

However, key attachments were not provided. Could DOE provide key attachments to these

work orders? For example, key attachments HTF-SKM-2014-00031 and HTF-SKM-2015-

00021 are requested. NRC also requested references related to the change to and testing 

of Grade 120 slag.

5. Could DOE clarify if all testing of Grade 120 slag is provided in VSL-15R3740-1? DOE 

indicated that information is provided in SRR-CWDA-2015-00088, but testing results do not 

appear to be included. What testing, if any, has been completed for tank fill, equipment, 

cooling coil, and clean cap grout prepared with Grade 120 slag?

6. With regard to presence of standing water and water removal in Tank 12H, DOE indicated

an expectation that water levels in the annulus could be reduced to no more than 2 inches 

by the water removal system and that the remainder had to evaporate. DOE was also 

prepared to remove accumulated water from the annulus into decant totes after annulus 

grouting had begun. Could DOE clarify how much water remained in the Tank 12H annulus 

prior to grouting and if 2 inches represents the limit to how much water can be removed by 

the water removal system (e.g., is the ventilation system used to remove additional water).

7. With regard to use of RECOVER, could DOE clarify why RECOVER dose was changed 

from 50 oz in Tanks 5F and 6F to either 30 oz or 60 oz in Tank 16H? Although a range is 

allowed to be used, it is unclear what led to the change.
- 72 -

Other Follow-up List of References, Questions from Tank 12/16 Grout TRR

1. Grout shrinkage testing report(s) (when completed).

2. Modeling files associated with SRR-CWDA-2015-00100 (evaluation of impact of clean cap 

grout in Tank 16H), if not already provided. 

3. Most recent version of SRR-CWDA-2012-00051. NRC staff think the most recent version 

may be “Critical Assumptions in the F-Tank Farm Operational Closure Documentation 

Regarding Waste Tank Internal Configurations.” Revision 2. Aiken, South Carolina: 

Savannah River Remediation, LLC. March 28, 2012.

4. Reference VSL-14R3330-1, which apparently provides documentation of tests with clean 

cap grouts mixed with the standard dry feeds while varying the water-to-premix ratio and 

adding NaOH solution to understand their resulting properties (e.g., total bleed, reabsorbtion time, flowability, and uniformity). This report was cited in SRR-CWDA-2014-

00011.

5. SRR-CWDA-2014-00011 appears to contradict information provided by DOE during the 

May 17, 2016, teleconference regarding the impact of caustic on clean cap grout flowability. 

The report indicates, “As expected, lower water-to-premix [ratio] formulations produced less 

bleed water but also reduced the flowability of the mix. In addition, use of 6 wt% (1.6M) 

NaOH decreased the total bleed while still maintaining sufficient slump to facilitate flow once 

discharged into the SDU. The use of a caustic solution was intended to simulate the 

average concentration of free hydroxide in the DSS; the presence of hydroxide is known to 

enhance the dissolution of the slag component and the rate of slag hydration, which 

subsequently increases the degree of water chemically incorporated into the saltstone 

matrix.” In contrast, DOE contractors indicated that caustic would increase reactivity and 

decrease flowability. Could DOE please clarify?

6. Could DOE clarify if and why there are significant differences in saltstone versus clean cap 

grout compressive strength (see SRNL-STI-2010-00515 versus SRR-CWDA-2015-00160). 

Although the cure time and other factors may differ between different test results, it is 

unclear to NRC if significantly different compressive strengths should be expected for the 

two grouts under typical field conditions.

7. NRC staff requested a copy of the UWMQE that includes information on Grade 120 tank 

grout wet chemistry test, flow test, compressive strength test, bleed test, and heat of 

hydration charted over time. DOE indicates this information is contained in SRR-CWDA2015-00088. However, it is unclear that the requested information is recorded in this 

document. Also, has DOE performed similar evaluation for other reducing tank-closure 

grouts such as equipment, cooling coil, and clean cap grout?
- 73 -

8. The Tank 12H grout strategy did not discuss disposal of chromate-laden flushwater or a 

strategy for completely filling of the intact coils in any detail, instead referring to a related 

work order that was to have been developed. Could DOE clarify if the same strategy was 

used in Tank 12H which was used in Tank 16H and provide any related work orders for 

disposal of chromate-laden flushwater?

9. A supplier deviation disposition request (SDDR No. 13307) addressed the two highest bleed 

water test results, which were 3.3 and 8.9 percent for Tank 16H (SRR-CWDA-2015-00159). 

Could NRC obtain a copy of SDDR No. 13307 and any associated deviation disposition 

documents?

10. SRR-LWE-2014-00147 indicates contradictory approaches for Tank 12H: (1) vertical 

portions of the [ventilation] duct were to be filled after completion of the annulus bulk fill, and 

(2) to lessen the potential for duct collapse, the vertical section of the ventilation inlet duct 

will be filled with grout to grade level in parallel with bulk filling of the annulus. Could DOE 

clarify which approach was used?

11. Tank 12H was the first tank closure work order for which the maximum drop height was 

increased to greater than 5 ft (1.5 m). Could DOE confirm that the drop height was not, in 

fact, increased, and that there are now no plans to increase the drop height for tanks yet to 

be grouted as part of the closure process?