ML20234D488
| ML20234D488 | |
| Person / Time | |
|---|---|
| Issue date: | 11/17/1987 |
| From: | Hawkins E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Arthur W ENERGY, DEPT. OF |
| References | |
| REF-WM-73 NUDOCS 8801070055 | |
| Download: ML20234D488 (4) | |
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Docket File WM-73 PDR/DCS DBangart, RIV WM-73/TT0/87/11/02/0 T01sen DJacoby q RGonzales LLW Branch, WMLU NOV 171987 URF0:TTO Docket No. WM-73 j
0400WM073140E W. John Arthur, Acting Project Manager Uranium Mill Tailings Project Office -
U.S. Department of Energy ,'
Albuquerque Operations Office .s P.O. Box 5400 g Albuquerque, New Mexico 87115 j
Dear Mr. Anderson:
Staff review of the Remedial Action Plan and Final Design for Tuba City has been completed. The areas that most comments fall under are Geotechnical Engineering and Surface Water Hydrology. There are still concerns dealing with ground water; however, these will not be addressed at this time due to ongoing development of pertinent regulations.
Should you have any comments or questions, please contact Mr. Tom Olsen A of my staff on FTS 776-2813.
Sincerely, ,
/s / >
l Edward F. Hawkins, Chief I Licensing Branch 1 Uranium Recovery Field Office Region IV
Enclosure:
Comments cc: Debbie Mann, DOE 8801070055 071117 PDR WASTE PDR WM-73 0FC
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DATE :87/11/17 -
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1 NOV 171987 NRC Comments on Remedial Action Plan and Final Design for the Tuba City UMTRA Project Surface Hydrology Calculation No. 18-890-02, Volume V, Supplement, Final Design -
April 1987 Page 2 of 3 shows that dense basalt is to be oversized by 7.7 percent using a factor of 2 for frequently saturated areas. This is not correct.
For frequently saturated areas, oversizing factor should be 10.
Therefore, oversizing should be 5 times what MKE determined or 5 (7.7) =
38 percent.
Page 2 of 3 states that absorption should not be included in the specifications because absorption is not used in the oversizing equation.
We do not agree, absorption must be included.
Dense Basalt - Absorption varies 1.5 percent to 2.1 percn t Vesicular Basalt - Absorption varies 3.5 percent to 3.8 percent On page 2 of calculation No. 18-890-03, Volume V Supplement, April 1987, the proposed rock source is Dense Basalt. Therefore, the absorption specification should be set at not more than about 2.5 percent.
Stability
- 1. The design values presented in Appendix D of the RAP are not in agreement with the parameters used in the stability models.
Specifically, please clarify why the undrained shear strength cohesion value of the radon barrier material was increased to 520 psf from 260 psf.
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- 2. It is difficult to evaluate the results of the stability model as it i appears that only selective results were submitted. Please submit the entire output for each computer run or as a minimum, the input data summary and minimum circle results for each separate run. ,
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- 3. The evaluation of the results did not consider shallow sloughing failures of the cover systems to be of any significance. As the integrity of the cover system will be instrumental in supporting the i design life of the facility, you will need to submit an evaluation of modeling of shallow failure circles which would disrupt the cover system.
NOV 171987
- 4. A dynamic analysis was not submitted. Please address why a pseudo-static analysis for the facility was deemed appropriate. l Liquefaction
- 1. You submitted four different liquefaction analyses using four different methods. Of the four, three (Koizumis, RD, Seed-Idriss) indicate that material may be liquefiable and only one (Chinese) shows no liquefaction. How does this support the conclusion that there will be no liquefaction concerns?
- 2. Your analyses utilized average SPT blowcounts, factors of safety, clay contents, etc. Liquefaction studies generally search for any liquefiable zones, rather than overall evaluating stability. Please discuss why the use of average values is appropriate.
- 3. An in-house analysis identified two layers of foundation material in TAC boring 820 as possibly being liquefiable. The NRC analysis, as in your analyses, was required to make certain assumptions such as saturation and sand densities. Please re evaluate the soils in this area.
- 4. The areas identified as " sand" in figure 3.2 of the RAP, would generally be the areas studied for liquefaction. There was, however, only one boring, TAC boring 820, in,these areas. Please establish that the " sand" areas cannot, over the design life, become saturated or submit additional borings and the associated analyses.
Settlement >
- 1. The in-house review of the settlement calculations was performed by radomly selecting several profiles and verifying your CONSOL modeling. After discussions with the TAC due to the numerical type of errors in the modeling, it is recommended that the calculation be revised by correcting several of the models. The impact of the corrections may demonstrate conservatism or may demonstrate the need for additional study. You will need to determine the impact on i primary and differential settlement of correcting the models and, if necessary, submit a corrected calculation that has been independently checked.
- 2. The cracking potential of the cover was evaluated by assuming a plasticity index (PI) of eleven for the soil. Please indicate how this analysis is representative of actual field conditions, as no requirement for PI is included in cover material selection process.
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3 NOV 171987 s
j Radon Barrier The final design of the radon barrier will be evaluated when it is submitted. To facilitate the review of the final cover, the dispersive and shrinkage characteristics of the selected soil materials will need to be addressed in the final design package.
Construction
- 1. As mentioned previously, the specifications do not require that the radon barrier materials meet any requirements for PI, as acceptable material will be classified as SC or SM. These two soil types do not limit Pls to any specific range. As discussed extensively for the Lakeview, Oregon, site, limits should be established on the acceptable lower bound of Pl. This will be a condition for concurrence in the RAP.
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