ML20234E204
| ML20234E204 | |
| Person / Time | |
|---|---|
| Issue date: | 11/20/1987 |
| From: | Lohaus P NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Arthur W ENERGY, DEPT. OF |
| References | |
| REF-WM-54 NUDOCS 8801070484 | |
| Download: ML20234E204 (5) | |
Text
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$ p;oyff YiM Record File W! John Arthur, Acting Project Manager Dxbtk.['
Uranium Mill Tailings. Project Office-Paa U.S. - Department of Energy ;
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Albuquerque Operations-Office
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P.O. Box 5400 j-
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Albuquerque, NM 87115.
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Dear Mr. Arthur:
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Enclosed are NRC geotechnical engineering coments on the Phase II Preliminary Design Documents for the Grand Junction, Colorado uranium mill tailings site.
A number of these courents were provided in draft form for discussion at the On-board Review meeting in San Francisco November 2,1987.
A general concern raised in these coments is that the parameter values used in the design calculations reviewed have not been adequately justified.
In addition, sone of the parameter values' presented in the preliminary desi different from those values reported in the draft Remedial Action Plan (gn are dRAP) with no explanation for the changes provided.
In subsequent. design documents, on this and other sites, DOE should provide the basis-for. parameter values used and explain changes made to these parameters in development-cf the design.
Please contact Susan Bilhorn at FTS 427-4145 if you have any questions on the enclosed connents.
Paul H. Lohaus, Chief Operations Branch Division of Low-Level Waste Management and Decouaissioning
Enclosures:
As stated cc: Karen Agogino, D0E/AL - TAC DISTRIBUTION:
bLLWM s/f NMSS r/f LLOB r/f SBilhorn, LLOB MFliegel, LLOB PLohaus, LLOB JSurmeier, LLTB MKearney, LLRB-DWidmayer, LLTB MTokar, LLTB JGreeves, LLWM MKnapp, LLWM hV Ar6 A (a f)
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OFFICIAL RECORD COPY esolo704s4 g733po PDR WASTE WM-54 PDR
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W. John Arthur, Acting Project Manager Uranium Mill Tailings Project Office U.S. Department of Energy Albuquerque Operations Office P.O. Box 5400 Albuquerque, NM 87115
Dear Mr. Arthur:
Enclosed are NRC geotechnical engineering comments on the Phase II Preliminary Design Documents for the Grand Junction, Colorado uranium mill tailings site.
A number of these comments were provided in draft form for discussion at the On-board Review meeting in San Francisco November 2, 1987.
A general concern raised in these comments is that the parameter values used in the design calculations reviewed have not been adequately justified.
In j
addition, some of the parameter values presented in the preliminary design are different from those values reported in the draft Remedial Action Plan (dRAP) with r.o explanation for the changes provided.
In subsequent design documents, on this and other sites, DOE should provide the basis for parameter values used and explain changes made to these parameters in development of the design.
Please contact Susan Bilhorn at FTS 427-4145 if you have any questions on the 1
enclosed comments.
)
Paul H. Lohaus, Chief i
Operations Branch Division of Low-Level Waste Management and Decommissioning
Enclosures:
As stated cc:
Karen Agogino, DOE /AL - TAC DISTRIBUTION:
i LLWM s/f iNMSS r/f LLOB r/f SBilhorn, LLOB MFielge, LLOB PLohaus, LLOB JSurmeier, LLTB MKearney, LLRB JGreeves, LLWM MKnapp, LLWM DWidmayer, LLTB MTokar, LLTB i
0FC: LLOB
- LLOB
- LLOB b
F hege NAME SBi M
PLohaus DATE:87/11/A) :87/11/
- 87/11/
0FFICIAL RECORD COPY
Page 1 of 3 NRC STAFF GE0 TECHNICAL ENGINEERING COMMENTS ON THE PRELIMINARY DESIGN FOR GRAND JUNCTION, COLORADO GT/1 - Low Permeability Layer, Subcontractor Documents, Pg 3 In the Information to Reviewer (page 3) 00E states that, "The subgrade at the excavated disposal site will be scarified and compacted to 90% of Proctor Density (ASTM-0698). TAC agreed that a low permeability layer was not neces sa ry. "
l DOE should explain why the low permeability layer is not necessary and demonstrate that the permeability of the existing foundation soils will be adequate, following proposed scarification and recompaction.
GT/2 - Radon Barrier Thickness, Specification Section 02200, Pg 7 Specifications for the Radon Barrier Materials state that, "... Radon barrier materials shall be Contractor-furnished materials stockpiled on the disposal site by others."
The dRAP (page 33~) indicated that the borrow for the radon barrier would i
be obtained by selective stockpiling of the foundation excavation material. The information found in " Calculations, Volume I" of the l
Preliminary Design Documents on availability of radon barrier material (Calculation No. 05-618-03-00) shows that the intended source of radon i
barrier materials is excavated foundation materials.
Calculations for the appropriate radon barrier thickness are also based on the use of excavated foundation materials (Calculation No. 05-670-01-00).
The relationship between excavation foundation soils and contractor-furnished material is unclear.
Therefore NRC is concerned that the thickness calculated for the radon barrier may not edequately represent the material to be used. DOE should correct this discrepancy and show that the material tested to calculate the radon barrier thickness is representative of the radon barrier material to be used, i
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Page 2 of 3 GT/3 - Shear Strength Values for Geotechnical Engineering Analyses NRC has the following concerns regarding some of the shear strength L
values used in the geotechnical engineering analyses presented in the Grand Junction Phase II Design Documents. These concerns were previously.
expressed in NRC etaff Geotechnical Engineering comment No. 1 on the dRAP.
1 a)
Main Pile Tailings - NRC staff expressed concerns regarding the values presented in Table E.6.7 and the value used in the slope stability analysis (37 ).
The values used in analyses supporting the preliminary design are conservative within the range of values referenced in the dRAP (Vick, 1983).
However, the applicability of these values should be demonstrated by laboratory testing results, or other appropriate justification, b)
Radon Barrier Materials - The value reported in the dRAP for phi in the long-term shear strength analysis of the radon-barrier materials was 33. However the value reported in the preliminary design is O' (Calculation No. 05-670-05-00).
This value is used in both the settlement and cover cracking analysis (Calculation No.
05-670-03-00) and the slope stability analysis (Calculation No.
05-670-04-00). The reason for this change has not been-provided nor has the use of the 0 long-term sheer strength value been justified.
c)
Foundation Soils Layer 2 - NRC staff expressed concern regarding the shear strength parameter values of foundation soil layer 2 (labeled-soil layer #5 in the dRAP) used in the geotechnical engineering-analyses.
In both long-and short-term analyses of slope stability, values presented.in the preliminary design for this soil layer are different than the values reported in the dRAP. DOE should note such changes and provide test results to support.the new parameter values, d)
Triaxial Testing - NRC staff. expressed concern regarding the shear strength parameter va' lues used as a result of non-standard staged triaxial tests. 'With respect to the values used in the phase II preliminary. d(sign, this concern has not been resolved. Data being collected on contaminated material and Cheney Reservoir soils should include results from triaxial testing using standard engineering practice.
If staged triaxial tests are being conducted, then DOE should show that the results from them are representative of' values that would be obtained using the standard methods described in the staff's Geotechnical Engineering comment No. 1 on'the dRAP. 'If no additional triaxial tests are planned at this time, then DOE should demonstrate that results from the triaxial tests conducted to support the dRAP are representative of results that would be obtained using standard techniques.
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Page 3 of 3 GT/4 - Foundation Soil Layer 4, Calculation # 05-670-03-00 and # 05-670-04 The ideolized cross sections of the Cheney Reservoir Disposal site used l-with slope stability analysis in the dRAP identify a layer of weathered clay as soil layer'#6.
In the preliminary design this same layer, labeled as foundation soil layer #4, is identified on' sheet #6 of l
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Calculation No. 05-670-05-00, " Material Properties - Summary." While sheet #6 is identified as a " typical cross section",-in the calculations on settlement and cover cracking (Calculation No. 05-670-03-00) and' slope.
stability (Calculation No. 05-670-04-00) DOE has assumed that this layer i
does not exist.
i DOE should more fully characterize foundation ' soil layer #4 to justify the assumption that it does not need to be considered in the engineering analysis.
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GT/5 - Parametric Values, Calculation # 05-670-05-00 and # 05-670-03-00 In Calculation No. 05-670-05-00, " Material Properties - Summary," the values for the following parameters are not the same values used in Calculation # 05-670-03-00, " Settlement and Cover Cracking":
i a) Main Pile Tafling, Shear Strength, Undrained, Phi b) Radon Barrier, Material Type, Maximen Rock Size c) Radon Barrier, Material Type, Minimum Passing #200 sieve d) Radon Barrier, Material Type, percent finer than 1.002.mm e) Radon Barrier, Permeability f) Erosion Protection, Material Type, Type A g) Erosion Protection, Material Type, Type 8 h) Foundation Soil #2, Permeability
- 1) Foundation Soil #3, Permeability J) Foundation Soil, Bedrock, Permeability DOE should resolve these discrepancies and assure that consistant l
parameters are used in the final design / RAP.
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