ML20205Q496
| ML20205Q496 | |
| Person / Time | |
|---|---|
| Issue date: | 05/08/1986 |
| From: | Nataraja M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Martin D NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| REF-WM-58 NUDOCS 8605280457 | |
| Download: ML20205Q496 (2) | |
Text
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Distribution:,
'" R: cord File WM Project 88' b
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- Docket tro. -
MAY 8 1986 WMEG r/f i
PDM JGreeves DMrit uLgg.52 LPDR MNataraja t
SSmykowski
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MTokar BJagannath JBunting MEMORANDUM FOR:
Dan E. Martin, Section Leader PJustus Low-Level Waste and Uranium JLinehan Recovery Projects Branch REBrowning Division of Waste Management MJBell MKnapp FROM:
Mysore S. Nataraja, Section Leader DGillen Engineering Branch Division of Waste Management
SUBJECT:
WMEG PRELIMINARY REVIEW 0F CALCULATIONS PERTINENT TO THE SHIPROCK, NEW MEXICO RAD 0N BARRIER DESIGN (UMTRAP)
In response to Technical Assistance Request #WM-86379, we are providing a preliminary review of the calculations pertinent to the revised Shiprock radon barrier design. A review of the previous radon barrier design was provided by WMEG (TAR #85041, August 9, 1985) and we concluded that the cover thickness calculated from the limited available data did not provide reasonable assurance that the EPA standard would be met. DOE has performed additional testing of the borrow material and the results from the tests are presented with this revised design. Our present review consisted of an assessment of the appropriateness of selected radiological and engineering soil parameters and a confirmation of modelling results. We understand that our final review will be performed upon NRC's receipt of a formal proposed RAP modification.
Parameters that were reviewed include the long-term moisture content, diffusion coefficient, emanation coefficient, radium content, porosity, and bulk density of both the contaminated material and the radon barrier material. We were able to. determine the representativeness of the parameter values based upon sampling data, test results, and the methods used for value determination. As a result of our review, we find that these values are appropriate input for RAECOM modelling.
It should be noted, however, that three methods were identified by DOE for estimating the long-term moisture content of the radon barrier soil.
The value of this parameter which was used in DOE's flux analysis was estimated from a U.S. Soil Conservation Service (USSCS) computer program. Although the staff is unfamiliar with this computer program, the value is more conservative than the values obtained from laboratory tests which determined the negative 15-bar moisture content. Therefore, we consider the value estimated by the USSCS computer program to be an acceptable value. However, if DOE plans to use this computer program as the basis for estimating long-term moisture contents of cover soils at other UMTRAP sites, we recommend that a copy of this program A
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_2-as well as the accompanying documentation be provided to the staff for review as soon as possible. A copy of this program was previously requested when we reviewed the radon attenuation section of DOE's Technical Approach Document.
The RAECOM computer code was used to verify the results of the proposed radon barrier thickness. Although the calculated flux from the top of the pile will slightly exceed the EPA radon flux standard, the total flux from the disposal site does not exceed the EPA standard when averaged with the calculated flux from the sides of the pile.
It is our understanding that the radon barrier was designed in this manner because placement of cover material on the sides of the cell was initiated prior..to additional diffusion coefficient testing and the subsequent revision of the radon barrier design. Although this design meets the radon flux standard of 40 CFR Part 192, the staff discourages this practice.
Based on our preliminary review, we have not identified any issues which would prevent the staff from granting final concurrence in the radon barrier design upon receipt of the formal proposed RAP modification. Any questions regarding this preliminary review should be directed to Steve Smykowski of my staff on x74109.
ORIGINAL SIGNED BY Mysore S. Nataraja Mysore S. Nataraja, Section Leader Engineering Branch Division of Waste Management j
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OFC :WMEG
- WMEG JUWE :SSmykowski
- MNataraja DATE :05/ /86
- 05/ /86
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