ML19210C156
| ML19210C156 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 10/24/1979 |
| From: | Frederick Brown ARMY, DEPT. OF, CORPS OF ENGINEERS |
| To: | Knight J Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19210C154 | List: |
| References | |
| TASK-02-04, TASK-2-4, TASK-RR NUDOCS 7911130367 | |
| Download: ML19210C156 (2) | |
Text
1 1 Or-IHu AWAI IN WATERWAYS EXPERIMENT STATION. CORPS OF ENGINEERS P. O. BOX 631
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WESta is nr 79 SU3 JECT: Reviev'of Liquefaction potential at La Crosse Nuclear power plant, La Cross,e, Wisconsin
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OCT 2 4 ED Mr. J. P. Knight Division of Site Safety and Environmental Analysis U. S. Nuclear Regulatory Cc-4 ssie2 Washington, DC-20555
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Dear Mr. Knight:
As requested by Mr. John Greeves cf your office, ve have reviewed the report entitled " Liquefaction Potential at La Cresse Boiling Water Reactor (LACBWR) Site Near Genoa, Vernon County, Wisconsin," dated 10 August 1979, prepared by Danes & Moore for Dairyland Power Cooperative.
Dames & Moore used results of undrained cyclic triartal tests and dynamic stresses ccmputed using the cenputer code SHAKE to assess the liquefaction potential at the site. WES belieTes that the laboratory strength curves
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used in this analysis are unconservative.
Ctr erperience is that loose cohesionless material densifics when sa= pled, and this densification msy-be as great as 2 to 3 lb/cu ft.
Table 2 of Da:nes ts Moore's report indicates that the cpeci= ens further densified as additional 2 to 3 lb/
cu ft frc= the frozen condition tp the thaved and consolidated condition in the laboratory.
'"his. indicates a total increase in density the.t could
.be as great as k to 6 lb/cu ft from the in situ conditien, and ve esti= ate that the probable total increase in 'ensity is 3 to.4 lb/cu ft.
This is a substantial change in density when one considers that the ninimum density reported by Dames & Moore was approrfmntely 97 lb/cu ft and the maximum density approximately 114 lb/cu ft.
This increase in density has not been taken into account in the results presented by Dames & Moore.
It is our opinion that correction for this increase in density v4'i substantially reduce the factors of safety presented by Demes & Moore.
Consequently, we cannot conclude that the site is safe against liquefaction using this approach.
1321 025 og hO 7911130 3 0
19 OCT'79 t
WESGH EUBJECT: Review of Liquefaction Potential at La. C* osse Euclear Power Plant, La Crosse, Wisconsin If tee Standard Penetration Test (SPT) K values presented by Denes & Moore are corrected to an overturden pressure of 1 ton /sq ft and then conpared to the giriesl correlations between N values and liquefaction occurrence at Niigata, Japan,. factors of safety less than 1 are obtained for fcunda-tion soils belov the water table down to a depth of about 35 ft.
Factors of safety are carginal from 35 ft do -'1 to a depth of about 40 ft.
.In sumscry, based on the judgment concerning the d uisity and strength
. data, on the analysis presented by Da=es & Mocre, an' on co= A '. sons of the SPT data presented by Dames & Moore with liqueiaction and SPT correlations at Niigata, l Japan, WES concludes that the foundation =aterial belov the water table down to a depth of approxi=ately h0 ft is not safe against liquefaction if the safe shutdown earthquake with a peak accelera-tion of 0.12 g occurs.
If you.have any questions regarding this reviev, please contact Dr. W. F. Marcuson, III, at FTS Sk2-2202.
Sincerely, F. R. ERO'n'N Engineer Technical Director O
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