ML20137U221

Concurs W/Change of Borrow Source for Radon Barrier Matl Proposed by DOE in Pid 11-S-14

ML20137U221
Person / Time
Issue date:	04/11/1997
From:	Cain C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Rael G ENERGY, DEPT. OF
References
REF-WM-86 NUDOCS 9704160324
Download: ML20137U221 (3)

Text

5 b April 11, 1997

• Mr. deorge.Rael, Acting Director U.S. Department of Energy Albuquerque Operations Office ERD /UMTRA P.O. Box 5400 Albuquerque, NM 87185-5400

SUBJECT:

REVIEW OF PROJECT INTERFACE DOCUMENT NO. 11-S-14 FOR THE SLICK ROCK DISPOSAL SITE

Dear Mr. Rael:

On September 5, 1996, the U.S. Department of Energy (DOE) *2 .smitted Class II Project Interface Document (PID) No. 11-S-14 for the Slick o ck, Burro Canyon disposal cell to the U.S. Nuclear Regulatory Commission. PID 11-S-14 proposes a change in the borrow source for the radon barrier material. Based on its review, the NRC staff has concluded that the subject PID should be classified as a class I change, because it involves changes to the radon barrier material; therefore, the PID was reviewed by the staff.

Based on the information provided by DOE, t he staff concurs in the change of borrow source for radon barrier material proposed by DOE in PID 11-S-14. The staff's review is documented in the enclosed Technical Evaluation Report.

If you have any questions concerning this letter or the enclosure, please contact the NRC Project Manager, Charlotte Abrams, at (301) 415-5808.

Sincerely, (Original sianed byl Charles L. Cain, Adting Chief Uranium Recovery Branch Division of Waste Management Office of Nuclear Material Safety and Safeguards

Enclosure:

As stated t

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. TECHNICAL EVALUATION REPORT

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1. - COLORADO. PROJECT INTERFACE DOCUMENT 11-S-14 7 ,

SITE: Slick Rock, Colorado LOCATION: Burro Canyon Disposal Site PROJECT MANAGER: Charlotte'Abrams TECHNICAL REVIEWER: Elaine Brummett

SUMMARY

U.S. Department of Energy (DOE) Project Interface Document (PID) 11-S-14 allows material from the offsite Sukla borrow source to be used as radon barrier material. instead of or blended with, the previously approved Burro Canyon borrow material [U.S. Nuclear Regulatory Commission Technical Evaluation Re) ort (TER. Seatember 30. 1996) for the Remedial Action Plan for the Slick Rocc site and TER for PID 11-S-03]. Test data (PID Calculation 11-535-01-00) were obtained for two borrow source options: all-Sukla material and

'a blend of 1.4:1. Burro Canyon to Sukla material. The radon flux was estimated (PID Calculation 11-535-02-00) based on blended radon barrier material with a model including a 1.5-foot-thick radon barrier plus a 2-foot-thick frost barrier of Burro Canyon material. DOE indicated that the geotechnical test data for the all-Sukla material are more conservative than data for the blended material: therefore, a radon flux analysis of the all-Sukla material was not performed.

DOE CODE INPUT August 19. 1996. Sukla/ Burro Canyon blended barrier, average values, calculation 11-535-02-00 LAYER / THICK POROS- DENS. Ra-226 Rn MOIST. DIF.COEF MATERIAL (cm.) ITY (g/cm2 ) (pCi/g) EM.  % by wt. (cm2 /s)

1. NC 762 .44 1.51 345 .42 8.5 .019 i l

material

2. UC Tailing 1067 .46 1.46 135 .19 4.3 .029

)

3. UC off and 853 .39 1.64 35 .32 (was9.4) .019 sub pile 8.0

4. Rn Barrier 45 .366 1.72 0 -

13.9 .002-

1. samples (3 sg) (6) (5) (5)

5. Frost 61 .46f 1.56 0 -

6.0 .039 Barrier assumed calc

1. samples (21sg) (8) 0 0 19 in 0 situ 9.1 14C = North Continent: UC = Union Caroide; sg = specific gravity DOE's analysis indicates that the2 radon flux from the top of the2 frost protection layer will be 2.7 pC1/m s. which is below the 20 pCi/m s limit.

ENCLOSURE

[ TECHNICAL EVALUATION-a

' hh change in the borrow source for the Slick Rock disposal site will result in changes in the radon flux model. parameter values 'for the contaminated materials, with the exception of the long-term moisture content of the UC off-

-pile and'sub-pile material. The moisture content value was reduced from 9.4

(.0 percent, based on recent 15 bar capillary moisture testing. The change cceptable:. however, the NRC staff recommends that, DOE confirm lthe o>ffusion coefficient of this material during construction-and, in its final

-flux analysis' for the site Completion Report, provide a calculation of the radon-diffusion coefficient using the revised moisture value.

I ENCLOSURE t