ML20211D044
| ML20211D044 | |
| Person / Time | |
|---|---|
| Issue date: | 08/05/1999 |
| From: | Johnson T NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Surmeier J NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| Shared Package | |
| ML20211D031 | List: |
| References | |
| NUDOCS 9908260156 | |
| Download: ML20211D044 (3) | |
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UNITED STATES p-y,
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WASHINGTON, D.C. 2055lH)o01 p
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August 5, 1999 j
MEMORANDUM TO: John Surmeier, Chief Uranium Recovery and Low-Level Waste Branch Division of Waste Management, NMSS wy i
FROM:
Terry C. Johnson, Senior Technical Reviewer
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Uranium Recovery and Low-Level Waste Branch Division of Waste Management, NMSS
SUBJECT:
SITE VISIT TO SHERWOOD URANIUM MILL TAILINGS SITE INTRODUCTION l
On May 20,1999, I visited the Western Nuclear incorporated (WNI) Sherwood tailings site near Spokane, Washington. The purpose of that visit was to evaluate site conditions in preparation for receipt of the submittal of the Long-Term Surveillance Plan (LTSP) by the Department of Energy (DOE). DOE had informed the staff that the LTSP would be submitted by about August 1,1999. As stated in 10 CFR 40.28, the Nuclear Regulatory Commission (NRC) will review and accept the LTSP. Thus, the site visit was intended to determine if there were any significant site conditions that should be addressed in the LTSP.
During the site visit, I was accompanied by several representatives of the Washington Department of Health (WDOH), Shepherd Miller incorporated (SMI), WNI, and DOE. Those present included:
G, Robertson (WDOH)
D. Stoffel (WDOH)
E. Fordham (WDOH)
B. Deward (WNI)
R. Edge (DOE)
C. Jacobsen (DOE)
L. Miller (SMI)
OBSERVATIONS During the site visit, I observed that the riprap on several portions of the site had apparently not been placed in accordance with the construction specifications. In particular, the large riprap that was placed in the diversion channel confluences appeared to have areas where the rock was not placed to the specified thickness and gradation. At the time of the site visit, I had not reviewed the construction requirements. Therefore, the following observations are based on WDOH's statements regarding the required rock size, rock thickness, and rock durability in various areas of the site.
9908260156 990812 PDR STPRO ESQWA PDR
e L.1 J. Surmeier, (1) Rock size l observed various areas where the rock apparently did not meet the required rock size. This was caused by placement practices that segregated the rock into areas where the smaller rock was concentrated into distinct areas where the rock size was smaller than specified and the layer thickness was thinner than specifed.
(2) Rock laver thickness I observed areas where the rock had been placed in layers that did not meet the required
~ thickness. I also observed areas where the rock had been. unevenly distributed in areas that were not as thick as specified, immediately adjacent to windrowed areas (mounds of rock) that were thicker than specifed, creating uneven surfaces on the cover that could produce flow concentrations that could exceed design conditions. I observed numerous bare areas where the underlying filter was exposed and had no rock covering at all. These bare spots existed primarily in the confluence channels.
(3) Rock durability
' I observed that many of the individual rock pieces exhibited cracking and spalling. It is possible that the rock quality may not meet the required construction specifications, based on this apparent short-term deterioration. In discussions with WDOH, it was stated that only a small fraction of the rock is actually deteriorating and, therefore, the overall rock quality should be satisfactory. However, it is possible that the rock that now looks satisfactory could weather significantly over a short period of time, based on WDOH's statements that the rock is predominantly a quartz ~monzonite. Such rocks are generally composed of feldspars that can rapidly weather to clays under certain physico-chemical conditions. It ir not evident if such conditions will occur at the Sherwood site.
The above observations were discussed with the participants. I indicated that I would coordinate my report with the NRC Office of State Programs (OSP). No formal commitments were made regarding future actions that should be taken by WDOH or would be taken by the
. NRC staff, nor did I state any official NRC position regarding the durability and placement of the rock.
DISCUSSION Erosion ' protection design and placement guidance is presented in the Final Staff Technical Position (FSTP)" Design of Erosion Protection for Stabilization of Uranium Mill Tailings Sites."
With regard to rock placement, the FSTP (page 18) suggests that, in general, proper placement is created by providing a uniform thickness of rock at the specified gradation and provides several recommendations for achieving proper placement. Further, the FSTP (page D-24) discusses the importance of the absence of clay minerals and further suggests (page D-28) that rocks composed of certain clays are not suitable for long-term stability applications.
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J. Surmeier I did inform WDOH representatives that additional field studies could determine whether the rock placement met the construction specifications and that petrographic examinations of the rock could determine the presence or absence of clay minerals. I suggested these actions to WDOH as one approach for demonstrating the durability and placement of the rock.
I have photographs that document my observations related to rock placement and rock durability, if you have any questions, please contact me at (301) 415-6658.
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