ML20213D962
| ML20213D962 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 01/15/1982 |
| From: | Gupta D Office of Nuclear Reactor Regulation |
| To: | Lear G Office of Nuclear Reactor Regulation |
| References | |
| CON-WNP-0444, CON-WNP-444 NUDOCS 8201280078 | |
| Download: ML20213D962 (4) | |
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!!E!!0RA!!DU*t FOR: George Lear, Chief
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llydrologic and Geotechnical Engineering Branch Division of Engineering
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Lyman H. Meller, Leader, Geotechnical/ngineering Section i
Hydrolocic and Geotechnical Fngineering Cranch j
Division of Engineering i
i FROM:
Dinesh C. Gupta, Geotechnical Encincering Section i
Hydrologic and Geotechnical Engineering Cranch i
Division of Engineering 4
SUBJECT:
REPORT OF SITE VISIT TO UPPSS f:UCLEAR PROJECT fiO. 2 (Ui!P-2) 0:1 DECEMr.ER 7,1931 A.
CAC!:GROUilD J
During the FSAR soil exploration stage at UflP-2 site, applicant's field and laboratory soil investioations indicated that the upper 40 feet of the in situ soils ranged from noderately dense to very loose glacio-fluvial soils. Therefore, they decided to excavate down to about 40 feet, or lo'.ver, to the pop of the dense Ringold Fomation and to backfill up to the base of the seismic Category I foundations with granular soil compacted by vibratory compacting equipnent to a mininun of 75% relative density and an average of 85" relative density, as detemined by AST1 D2049-69. This Quality Class I backfill was placed before t'ay 1976 and was found by the applicant to confom to PSAR requirements. After liay 1976, excavations were made in this backfill'for installation of renote air intake pipino, the remote air intake structures, and the standby service water pipeline with parallel duct bankt. Backfill subsequently used in these excavations was found by the applicant not to conform to the above Quality Class I specifications with respect to qradation and compaction. The specifications called for the excavation backfill naterial to be compacted to an average relative density of 85 percent, with a nininun relative density of 75 percent.
In addition, the backfill materials were specified to consist of inorganic sand er sand and gravel mixtures ivhich were free of boulders and cobbles greater than 3 inches and contained 5 percent or less fine grained, non plastic natorials passing
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NRC FORM 318,(10-80) hRCM 024o OFFICIAL RECORD COPY uscro: sen--mooo
s George Lear JM! 15 SS2 i
a 200 mesh sieve. Applicant's investigations of the backfilled excavation areas indicated that the majority of this backfill was poorly graded sand containing from four to ten percent fines. Also, the conpacted density was found to be erratic and varied from loose i'
to very dense with extrene values of SPT b w counts ranging from 3 to 100.
l At the site, the design ground water table is lower than the botton i
of the excavations for the pipeline ducts and air intake structure i
andtherefore,thebackfillinquestionisabovetpeplantdesign water table.
On March 20, 1931, the applicant infomed f!RC staff by telehhone of the potentially reportable condition (10 CFR 50.55(c) Condition
!!o. 146).
Interin reports on this condition were submitted to !!P.C staff on April 22, September 1, and f!ovember 12, 1931 (Refs. 1, 2, and 3).
This potential deficiency which indicates that excavation backfill does not fully meet the PSAR requirencnts with respect to the conpaction and gradation specifications is tihe only geotechnical enoineering open iten in the nortion of !!!:P-2 draft SER prepared ty Geotechnical Section Staff in October 1901.
In an attenst to nake cositive progress in the safety review, a site visit was planned for December 7,1901 to discuss the unresolved issue uith the applicant.
D.
PtfRPOSE OF VISIT The purpose of my visit to !!flP-2 site on December 7,1931 was to review the site and soil conditions along the alignments of the remote air intake piping and the standby service unter pipeline with parallel duct banks, and surrounding the remote air intake structures.
In addition, we intended to discuss the progress report on the applicant's testing progrc.m to detemine the extent of the area with potential deficiency, and their evaluation of the effect of the potential deficiency on safety related buried piping.
C.
PEOPLE C0HTACTED The following persons ucre contacted at the site during tlie field tour and the office discussion which followed:
Ed Fredenburg, l'ashington Public Power Supply Systen (ifPPSS)
R. fl. tielson, !!ashington Public Power Sunply Systen (!1PPSS)
L. tioble, Durns & Roe l
D.11. Brown, turns & Roe
?!att Giannini, Curns & Roe Ed Zisnan, Burns & Roe i
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idRC FOCM 316 (10-80) f4RCM 024a OFFICIAL RECORD COPY usam mi-mw
George Lear j.it! 15 1932 D.
VISIT ACTIVITIES The activities at the 1.tP-2 site consisted of a walking tour along part l
of the alignaents of the renote air intake piping and the standby service water pipeline with parallel duct ban W.
The field tour was l
followed by an office discussion with the !!PPSS representatives to discuss the interin progress reports (Ref. 1, 2 and 3) on the investigations l
fortthe 10 CFR 50.55 (e) condition fio.146.
E.
INFORitATIO4 GAINED A'iD GEffEp.AL OBSERVATI0f!S The aoplicant indicated that they have completed their investigation of the areas where compaction specifications were not fully net, and gave ne a prolininary copy of their final report on the issue. They indicated that, based on the investigations and analyses of these areas, they have concluded that stress conditions resulting from potential static and dynamic settlenents in the unsaturated, loose soil :ones under question will have no detrinnental effects on safety related buried piping.
In addition, since none of the backfill in question is used to support seismic Catecory I buildings, the safety of these structures is not affected.
The staff indicated that we will review the applicant's report (Ref. 4) and incorporate our evaluation into the draft SER Section 2.5.4.
F.
PIFEREffCES 1.
Letter fron R. G. Matlock, uashington Public Power Supply System, to R. ii. Engelken, i:RC,
Subject:
UPPSS Muclear Project !!o. 2 Potentially Reportable Condition - 10 CFR 50.55(e) Soil Cachfill, Conpaction and Testing, dated April 22, 1981. Available in !!RC PDR for inspection and copying for a fee.
2.
Letter from R. G. !!atlock, Uashington PuSlic Power Supply System, to R. ft. Engelken,flRC, SuSject: Supply System fluclear Project flo. 2 Reportable Deficiency - 10 CFR 50.55(e) flo.146 Potentially Reportable Condition en Soil Cackfill, Connaction and Testing, dated September 1,1831. Available in flRC PDR for inspection and copying for a fee.
3.
Letter from G. D. Douchey, I!ashington Public Power Supply System, to A. Scinzencer, !!RC,
Subject:
Supply System t!uclear Project flo. 2 Quality Class I Soil Cackfill Test Progran, dated flovember 12, 1981.
Available in MRC PDR for inspection and copying for a fee.
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renc ronu us oo-sowcu cao OFFICIAL RECORD COPY us m ini m.
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George Lear i JM,, 7.3 ;gg 4.
Letter fron G. D. Bouchey, Washington Public Poacr Supply Systen, to A. Schtfencer, NRC,
Subject:
l'uclear Project l'o. 2 Quality Class I Soil Backfill Test Progran, dated Deccaber 15, 1931.
Available in f!RC PDR for inspection and copying for a fee.
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Dinesh C. Gupta.
Geotechnical Enginc rinq Section Hydrologic and Geote-hnical Engineerinr1 Branch Division of Enqineering cc:
R. Vollner A. Schttencer J. I: night L. Heller l1. Fliegel G. Stalev R. Auluck D. Gupta R. Engelken, Reg. V.
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