September 25, 2007 

Keith Lockie 

NE-ID/ID-S 

FACILITY AND MATERIAL DISPOSITION 

U.S. Department of Energy 

Idaho Falls, ID 83401 

SUBJECT: NUCLEAR REGULATORY COMMISSION ONSITE OBSERVATION REPORT 

FOR THE IDAHO NATIONAL LABORATORY IDAHO NUCLEAR 

TECHNOLOGY AND ENGINEERING CENTER TANK FARM FACILITY 

Dear Mr. Lockie: 

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

observation activities on August 15, 2007, for monitoring disposal actions taken by the 

Department of Energy (DOE) at the Idaho National Laboratory (INL), Idaho Nuclear Technology 

and Engineering Center Tank Farm Facility (INTEC TFF). This onsite observation was 

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

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

Energy for the purpose of assessing compliance with the performance objectives set out in 

Subpart C of Part 61 of Title 10 of the Code of Federal Regulations. 

NRC’s onsite observation at INL was primarily focused on performance objective, 10 CFR 61.41 

by observing DOE=s tank grouting operations. Since the tank grouting operations will impact 

the long-term stability of the tank farm facility after its closure, this observation had also partially 

assessed the performance objective in 10 CFR 61.44. Additional visits will be conducted in the 

future to assess compliance with these and other performance objectives in 10 CFR Part 61, 

Subpart C. 

If you have any questions or need additional information regarding this report, please call me at 

301-415-6717, or call Xiaosong Yin, project manager on my staff, at 301-415-7640. 

Sincerely, 

/RA/ 

Scott Flanders, Deputy Director 

Division of Waste Management 

 and Environmental Protection 

Office of Federal and State Materials 

 and Environmental Management Programs 

Enclosure: NRC Observation Report 

 

Keith Lockie 
2 

NE-ID/ID-S 

 September 25, 2007 

FACILITY AND MATERIAL DISPOSITION 

U.S. Department of Energy 

Idaho Falls, ID 83401 

SUBJECT: NUCLEAR REGULATORY COMMISSION ONSITE OBSERVATION REPORT FOR THE 

IDAHO NATIONAL LABORATORY IDAHO NUCLEAR TECHNOLOGY AND 

ENGINEERING CENTER TANK FARM FACILITY 

Dear Mr. Lockie: 

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

activities on August 15, 2007, for monitoring disposal actions taken by the Department of Energy (DOE) 

at the Idaho National Laboratory (INL), Idaho Nuclear Technology and Engineering Center Tank Farm 

Facility (INTEC TFF). This onsite observation was conducted in accordance with the Ronald Reagan 

National Defense Authorization Act for Fiscal Year 2005 (NDAA), which requires NRC to monitor disposal 

actions taken by the Department of Energy for the purpose of assessing compliance with the performance 

objectives set out in Subpart C of Part 61 of Title 10 of the Code of Federal Regulations. 

NRC=s onsite observation at INL was primarily focused on performance objective, 10 CFR 61.41, by 

observing DOE=s tank grouting operations. Since the tank grouting operations will impact the long-term 

stability of the tank farm facility after its closure, this observation had also partially assessed the 

performance objective in 10 CFR 61.44. Additional visits will be conducted in the future to assess 

compliance with these and other performance objectives in 10 CFR Part 61, Subpart C. 

If you have any questions or need additional information regarding this report, please call me at 301-415-

6717, or call Xiaosong Yin, project manager on my staff, at 301-415-7640. 

Sincerely, 

/RA/ 

Scott Flanders, Deputy Director 

Division of Waste Management 

 and Environmental Protection 

Office of Federal and State Materials 

 and Environmental Management Programs 

Enclosure: NRC Observation Report 

DISTRIBUTION: EPAB r/f DMcIntyre (OPA) NJensen (OGC) TCombs (OCA) 

ML072570173

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

NAME X.Yin A.Kock J.Davis S.Flanders 

DATE / /07 / /07 / /07 / /07 

OFFICIAL RECORD COPY
1 

IDAHO NATIONAL LABORATORY IDAHO NUCLEAR TECHNOLOGY AND ENGINEERING 

CENTER TANK FARM FACILITY

NRC ONSITE OBSERVATION REPORT 

1.0 BACKGROUND 

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

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

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

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

performance objectives in 10 CFR Part 61, Subpart C. 

The U.S. Nuclear Regulatory Commission (NRC) conducted its first onsite observation at the 

Idaho National Laboratory Idaho Nuclear Technology and Engineering Center Tank Farm 

Facility (INTEC TFF) on April 24–25, 2007. NRC activities during this visit focused primarily on 

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

of radioactivity, and 10 CFR 61.43, protection of individuals during operations. NRC also 

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

closure. A report that provided the results of the NRC onsite observation was transmitted to 

DOE on June 1, 2007 (Flanders, 2007). 

NRC had intended during the April visit to observe ongoing tank operations at the INTEC TFF. 

However, several days prior to the scheduled NRC trip, operational problems were encountered 

by the U.S. Department of Energy (DOE) contractor, CH2M-HILL and Washington Group, Idaho 

(CWI), during grouting of tank WM-182 and grouting operations were suspended in order to fix 

the problem. NRC was unable to observe any tank grouting operations in progress and its 

activities during the April visit were limited to a tour of the grout batch plant, review of records, 

and interviews with CWI staff. Thus, NRC conducted a second onsite observation at the INTEC 

TFF on August 15, 2007, to observe ongoing tank grouting operations and to followup on issues 

remaining from its first visit. 

2.0 NRC ONSITE OBSERVATION ACTIVITIES 

2.1 Grout Formulation and Performance 

2.1.1. Observation Scope 

The observation of DOE tank grouting operations is related to Key Monitoring Area (KMA) 2, 

“Grout Formulation and Performance” identified in the NRC monitoring plan for the INTEC TFF 

(NRC, 2007). An objective of NRC monitoring activities related to KMA 2 is to ensure that the 

final grout formulation used to stabilize the INTEC TFF waste is consistent with design 

specifications assumed in the final waste determination (DOE-ID, 2006), or that significant 

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

grout. 

2.1.2 Observation Results 

NRC observed ongoing tank grouting operations at the INTEC TFF. NRC visited the batch plant 

and observed the preparation of controlled low-strength material (CLSM) grout components and 

placement into cement mixer trucks. Preparation of grout mixtures at the batch plant is 

computer controlled and for each batch (or truckload) of grout, a ticket is prepared documenting 
2 

the mix description, volume of material in the mix, percent moisture of the sand, and water to 

cement ratio, using State-certified calibrated equipment. At the INTEC TFF, NRC observed the 

transfer of the grout mixture from the mixer truck to the boom pump truck and subsequently to 

the waste tank’s surrounding vault. NRC observed that procedures are being implemented to 

ensure radiation protection of workers at the INTEC TFF during the tank grouting activity. In the 

control trailer, NRC viewed the placement of the CLSM grout into tank WM-181 through a video 

camera located inside the tank. The tank video camera is able to pan and zoom on different 

areas inside the tank. NRC also observed through in-tank video cameras the condition of the 

grout that had been placed inside the large tanks WM-180 through WM-186. While residual 

flush water, which was used to rinse off the grout mast, was observed to be present in some 

tanks, no surface cracking of the hardened grout in any of the tanks was visible. Addition of the 

residual rinse water to the CLSM will not increase the water to cement ratio appreciably as the 

water was very small compared to the large volume of CLSM in the tank. 

NRC also watched videos of the engineered grout placement in tank WM-185. Two purposes of 

the segmented engineering grouting pours was to (1) attempt to remove additional liquid waste 

by directing it toward the pump and (2) to promote mixing of the engineering grout with the 

remaining waste that could not be extracted. By observing the video, the segmented pours 

provided opportunity to remove additional liquid waste as flow of water toward the pump could 

be seen. The star patterned segmented pours fold in the waste as they are placed. Layering of 

the grout pours was evident on the video. 

CWI staff indicated that sampling and testing of the CLSM grout is done twice a day—once in 

the morning (typically the first batch) and another in the afternoon. NRC observed the sampling 

of grout from the first grout batch of the day and the measurements of temperature, air content, 

unit weight, and puddle size, which were conducted in accordance with the “Compliance and 

Monitoring Plan for Performing Grouting at the INTEC Tank Farm Facility Closure Project” (CWI, 

2007). NRC noted that cylinder samples of the grout were set aside by CWI staff for later 7-, 

28- and 56-day strength tests. 

NRC also reviewed CWI records, including the ”Grout Supervisor Tracking Form,” “Truck 

Supervisor Tracking Form,” and “Tank Farm Inspection Planning Package” and verified that the 

required information have been filled in. The “Grout Supervisor Tracking Form” recorded the 

required and actual volume of each grout pour, the start and stop times of grout placement, and 

the tank riser number through which the grout was placed. The ”Truck Supervisor Tracking 

Form” recorded the required slump range and the actual slump measured. Information in these 

forms is monitored by the Grout Supervisor and Truck Supervisor as they are entered into the 

forms for any possible variance that could impact assumptions made in the final waste 

determination. Additional documents included with the “Tank Farm Inspection Planning 

Package” include the INEEL Construction Concrete Control Report, which provides results of 

laboratory material testing (e.g., 7–, 28–, and 56–day strength test) and of field tests (e.g., 

slump or puddle size, air content, grout temperature). The values recorded in the reviewed 

documents were determined to be within DOE specifications. 

DOE and CWI staff also indicated that grouting procedures have been revised to take into 

account the lessons learned from grouting tank WM 182. Prior to the previous observation trip, 

during tank WM-182’s engineered grout placement, both arms became lodged into an 

engineering grout pour. The lower section of one arm was left in place. Even with the one arm 

left in place in the grout, CWI was able to finish the star pattern, consistent with the planned 

approach for all the tanks. No appreciable effect on the degree of mixing is expected, however, 

a smaller amount of excess liquid was able to be extracted from the tank. This excess is 
3 

expected to be a very small fraction of the total activity remaining in the tank, and therefore, will 

have negligible impacts on performance. In addition to changing the procedures, the cameras 

in the tanks were upgraded to assist in avoiding similar problems in the future, as positional 

awareness of the end of the arms was identified as a contributor to the incident. 

2.1.2 Review of DOE Response to Request for Additional Information 

As a result of its first onsite observation visit in April 2007, NRC requested additional information 

from DOE regarding (i) the qualifications required of vendors to be on the approved vendor list 

and (ii) the minimum cure time between grout pours. NRC also requested documentation 

regarding the risk significance of the higher water to cement ratios, compared to that assumed 

in the performance assessment supporting the waste determination, of grout used to fill tanks 

WM-104, WM-105, and WM-106. In response, the DOE transmitted additional information to 

NRC on August 6, 2007 (van Camp, 2007). NRC staff reviewed the information after returning 

from its August 2007 onsite observation visit. 

Qualifications of Vendors on the Approved Vendor List

DOE indicated in its response that the subcontract with Valley Ready Mix, the grout component 

supplier, was developed and approved consistent with the CWI Management Control Procedure 

(MCP)–540, “Assigning Quality Levels” and MCP-1186, “Service Acquisitions,” which do not 

require Valley Ready Mix to be on an approved vendor list. However, DOE indicated that CWI 

evaluated Valley Ready Mix, including its Quality Assurance Plan, and determined that the 

company has the ability to comply with the contractual requirements of the tank farm grouting 

subcontract. NRC reviewed the Quality Assurance Plan of Valley Ready Mix and determined 

that Valley Ready Mix has procedures in place to ensure the grout materials it supplies CWI 

meet DOE specifications, in terms of constituent formulation and standard grout characteristics. 

The reducing capacity of the tank grout is important in mitigating the release of Tc-99, whereas 

the short-term performance of the grouted vault is important in mitigating the release from the 

contaminated sand pads of short-lived radionuclides, such as Sr-90, that could potentially 

dominate the predicted doses from the INTEC TFF within the first few hundred years. This is 

accomplished at INTEC TFF by adding blast furnace slag to the concrete. The amount of 

sulfide in the slag is important because it imposes on the grout a reducing condition that helps 

mitigate the release of Tc-99. The measured sulfide sulfur content of the slag listed in 

representative chemical test reports was found to be greater than the specified 0.7 weight 

percent minimum, during our April monitoring visit. However, these reports were from Valley 

Ready Mix’s supplier and not apparently independently verified. While Valley Ready Mix had 

procedures in place to ensure that it supplied grout materials consistent with DOE specifications 

for normal characteristics, it does not appear that any additional testing for sulfide content was 

performed by Valley Ready Mix of the slag they received from their supplier or that Valley 

Ready Mix verified, by independent testing, that their supplier had a proper quality assurance 

plan for the DOE application. In the future, DOE should consider whether specific additional 

requirements added to their contractor quality assurance program should be included to 

address non-standard grout characteristics that are relied on in the safety assessment. 

Additional quality assurance would strengthen their safety case. The NRC considers this issue 

closed. 

Minimum Cure Time Between Grout Pours

DOE provided a copy of a CWI engineering study documented in Engineering Design File 

(EDF)-8059, “Grout Temperature Increase for the INTEC Tank Farm Closure” (CWI, 2007), 
4 

which calculated the maximum temperature of the grout that would result from heat generation 

during cure of the CLSM. Two mathematical models were evaluated–an adiabatic model and a 

kinetic model–and conservative assumptions were used with respect to the placement 

temperature and the volume of each of the three grout lifts emplaced in the tank. Based on the 

results of the kinetic model, DOE indicated that the maximum temperature within the CLSM was 

142 °F, which is significantly below the acceptance criterion of 170 °F, and that no additional 

thermal-related controls need to be implemented by CWI. The 170 °F acceptance criterion was 

reported to have been conservatively selected from the literature for materials of higher strength 

than required of CLSM. 

NRC conducted independent calculations of the maximum temperature within the CLSM during 

cure using the method discussed in Bamforth (2007) and verified that the maximum temperature 

would be significantly below 170 °F. NRC noted that the analysis presented in EDF-8059 did 

not consider the temperature gradients in the grout monolith that could occur during cure. 

Temperature gradients lead to stresses that could result in formation of surface and interior 

cracks in the monolith (Bamforth, 2007). In a followup conference call, the DOE stated that the 

formation of early age cracks is bounded by the conservative assumptions regarding grout 

degradation used in the performance assessment supporting the waste determination. NRC 

concurs that the effect of early age cracking on radionuclide release is likely bounded by the 

conservative assumptions used in the performance assessment calculations and considers this 

issue closed. Nevertheless, engineering calculations may be useful prior to tank grouting at 

other DOE sites such that steps could be taken to limit temperature gradients and the potential 

for crack formation. The NRC considers this issue closed. 

Risk Significance of High Water to Cement Ratio Used for Grouting the 113.6-cubic meter 

(30,000-gallon) Tanks WM-104, WM-105, and WM-106

DOE stated in its response that no specific release model was developed for the 113.6 m3 

(30,000 gal) tanks for the performance assessment calculations supporting the 3116 waste 

determination. Therefore, no specific water-to-cement ratio for the 113.6 m3 (30,000 gal) tanks 

was assumed in the performance assessment supporting DOE’s waste determination. The 

reason for not including a release model for the 113.6 m3 (30,000 gal) tanks is the small 

radionuclide inventory in those tanks compared to the inventory in the 1,136 m3 (300,000 gal) 

tanks, and it was concluded that, for performance assessment purposes, the inventory for the 

large 1,136 m3 (300,000 gal) tanks bound any additional contamination that may be released 

from the 113.6 m3 (30,000 gal) tanks. Based on the small radionuclide inventory in the 113.6 

m3 (30,000 gal) tanks, the high water to cement ratio of the grout used in three of the four 

30,000-gallon tanks poses a low risk of significantly increasing the dose to the general 

population. The NRC considers this issue closed. 

2.1.3 Conclusions 

The NRC observation team observed ongoing tank grout operations and reviewed records at 

the INTEC TFF. NRC determined that the DOE and CWI quality assurance program pertaining 

to tank grouting, grout formulation, and placement is being implemented effectively. 

NRC has reviewed the documents DOE provided in response to an NRC request made during 

its April 2007 onsite observation visit. NRC is closing the issues from the April 2007 observation 

report as it has determined that satisfactory information has been received. 

For the issue on the qualification for vendors on the approved vendor list, DOE supplied 
5 

information on the quality assurance program of its vendor, Valley Ready Mix, which ensure the 

grout materials it supplies to CWI meet DOE specifications, in terms of constituent formulation 

and standard grout characteristics. NRC is recommending that if specific characteristics of the 

grout material, which are not part of the standard grout characteristics, such as the sulfide level 

of the slag, are being relied on for performance, specific requirements for testing should be 

added to the quality assurance programs. 

DOE provided adequate information for NRC to close the issue on the minimum cure time for 

the grout lifts. NRC is recommending that DOE remain cognizant of the potential for crack 

formation, which may be more of an issue at other sites which have not used very conservative 

assumptions for concrete degradation. 

The third issue addressed the water to cement ratio used in three of the small tanks, as 

compared to the water to cement ratio assumed in the waste determination. NRC determined 

that, based on the small radionuclide inventory in the 113.6 m3 (30,000 gal) tanks, the high 

water to cement ratio of the grout used in three of the four 113.6 m3 (30,000 gal) tanks poses a 

low risk of significantly increasing the dose to the general population 

3.0 PARTICIPANTS 

NRC Observation Team 

Andrea Kock 

Xiaosong Yin 

Chris McKenney 

Karen Pinkston 

Roberto Pabalan 

Idaho Department of Environmental Quality 

Bruce LaRue 

Partial List of DOE Representatives 

Keith Lockie, DOE-ID 

Mark Shaw, DOE-ID 

Keith Quigley, CWI 

Trent Harris, CWI 

Jeff Long, CWI 

4.0 REFERENCES 

Bamforth, P.B. Early-age Thermal Crack Control in Concrete. London, U.K.: CIRIA. 2007. 

CWI. “Compliance and Monitoring Plan for Performing Grouting at the INTEC Tank Farm 

Facility Closure Project.” PLN-2309, Revision 2. Idaho Falls, Idaho: CH2M-WG, LLC (CWI). 

March 2007. 

DOE-ID. DOE/ID–11226, “Basis for Section 3116 Determination for the Idaho Nuclear 

Technology and Engineering Center Tank Farm Facility.” Rev. 0. Idaho Falls, Idaho. DOE 

Idaho. November 2006. 
6 

Flanders, S. “Nuclear Regulatory Commission Onsite Observation Report for the Idaho National 

Laboratory Idaho Nuclear Technology and Engineering Center Tank Farm Facility.” Letter (June 

1, 2007) to K. Lockie, DOE. Washington, DC: NRC. 

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

U.S. Department of Energy at the Idaho National Laboratory Idaho Nuclear Technology and 

Engineering Center Tank Farm Facility in Accordance with the National Defense Authorization 

Act for Fiscal Year 2005.” Washington, D.C.: U.S. Nuclear Regulatory Commission. May 2007. 

Van Camp, S.G. “Contract No. DE-AC07-05ID14516—Response to Nuclear Regulatory 

Commission Onsite Observation Report of Tank Farm Closure Activities.” Letter (August 6, 

2007) to S. Flanders, NRC. Washington, DC: DOE.