ML20236F765
| ML20236F765 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 10/27/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20236F740 | List: |
| References | |
| NUDOCS 8711020286 | |
| Download: ML20236F765 (3) | |
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> SAFETY; EVALUATION'BY!THEc0FFICEOFNUCLEAR: REACTOR:REGULATIONyf$;m m.
i BASEMAT'CONFIRMATORIANAI.EES':AN050RYEILLhNCETPROGRAM;...
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! FACILITY OPERATING LICENSE N06 NPF-38 <
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1;0L' INTRODUCTION:
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LicenseiCondit'iEn2;C.17Softheloperating:!1 ice'nse"fdr$heWaterbdStead,1.)
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~ Electric:StationJ' Unit:3, operated byJLouisiana. Power andiLight)Companyj
- (LP&Lbthe ili.censee)frequires thatatheil1.censee ; perform [ confirmatory 1;,"
J analyses associated iith the Lstructura10 adequacy Lof? the: plant'. s acommoni foundation basemat andimonitor its? performance;j By lettersidated2Ju'nes26 V
and July 1,1987,lthellicensee submitted the" surveillance programlandJthem
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.resultsofthe;confirmatoryanalysesjprogram.4, ',
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2.0 DISCUSSION
- 9; AllstructuresoftheWaterford$nucleariplantisland0arelfoundE(on=ai common basemat.; The;basemst-isi380L feetf(in thelN-S direction) by '2677
, Eq feet:(in the.E-W direction) fin plan land,is?l2 feetithick!
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The mat was1 constructed in blocksfapproxim'ately;6'0$eetisquareb Construc--
N tion proceeded by first completing useverals blocks ?in-an 'E-W? strip; near the c
center of the mat and then pr.oceeding outLto thet northlandisouth e'nds:!of;
.the, mat.
This construction sequence combined'withitheLrelativelyflarge~-
q settlements,'resulted inl bending moments producing.tensilenstresses acting '
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Cracks were first'observedlinL the basemat$selfiinLJuly l' 77 whenith'e? '
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. areas were cleared of constructiontdebrisMThese, cracks lwere orie'nted ;
E in the'E-W directioniand:were: located inside:thefshield,buildingLareah The. licensee determined that theseicracks had Lno'lstructura1Lsignifican' et
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, and repaired them'with an epoxy! gel;priorfto'placementiof"filliconcreten w
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inside the: ring. wall.-
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si Additional basemat cracks were observed;in MayL1983,'whe'nNhe areafoutsidej the; shield. building 'was. cleared of constructionidebris tThese?newlytobservedi j cracks,Ltogether;with-those found in? July 1977,sformedLa(system 1ofdsevent i
major. cracks:thatappearedto;spanTacross;thefentireimat,. raising; questions 3 m
as to the impact such cracks might.have on the: performance,ofitheLmaty g
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-Several actions were taken prior ~to-full power: license issua'nce to resolve the; questions concerning:the' significance.of the cracks.
l A'non-destructive test program of the basematLwas conducted u' sing ~a 2
pulse-echo sonic technique to' define the geometry of the cracks.
The-results of this investigation ~ demonstrated that' the major cracks in?
the mat were/ vertically; oriented and deep eliminating'the 'concernc w
that the cracks _-might. be shear-induced.diagonalitensiont cracks"
-because such cracks would be oriented 45-' degrees:to the. vertical m
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rather than the vertical orientationiwhich was~ observed.
g The licensee undertook studies to interp et th'e:non-destructiveitesti p
' data and to evaluate the~ impact the crackssmight have on:the perfor-mance of the plant..ItLwas concluded'that the cracks 1.likely. occurred.
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during-the construction period and that the: cracked mat could safely'
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perform itsiintended. design: function during: normal" operationsfand!
accidenticonditions.
A series of studies were undertaken 1by BNL, ' acting as consultantsitoi the NRC staff, as'part of.the overall technical:reviewiofothe licensee-work. These studies included analytical and experimental w'ork' having I
the objective of providing independent-verification of:the studies-being performed by the licensee described above; The BNL studies; n
generally supported the' conclusions. developed 1by theflicensee.
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There were five areas, howeve'r, where.it was concluded that. additional j
confirmation was required. These five' areas l formed the bases'for1the-1 confirmatory analyses. requirement contained. in-the. license:
Dynamic Effects of Lateral soil / Water Loadings.
m Dynamic Coupling of the Reactor Building and Basemat.
Artificial Boundary' Constraints' in Finite Element Model.
Fineness of Finite Element Mechanics
.Basemat Construction Sequence' Analysis-are i
In addition to performing the confirmatory analyses described above,L the
. license condition required the licensee -to'instituteLa basemat-' surveillance program.
The. objective of this. program 41s to. ensure' that the mat performance is.astexpected.
The mat's response parameters being' monitored'includet l
settlement, groundwater,' chemistry, groundwater level,: and crack growth.
M In each of..the areas, except for groundwater level,L upset 1 values are ;
defined at which point the licensee must' inform NRC and perform an-engineering' evaluation of-the data.
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- 3. 0 EVALUATION-Brookhaven National Laboratory,.under contract' to the'NRC, has reviewed.
- 4 the confirmatory analyses and basemat surveillance program pequired by l
License Condition 2.C.17 of the Waterford operating license. Details,of a
.this review are contained in the attached Technical Evaluation Report (TER).
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TheLTER concludes?thatLthe confirmatory. analyses;haveidemonstratedithe:
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fadequacy.ofithelbasematLatWaterford-.3sandithattthebasematLsurveillance7 w
, program, which will.co.ntinueiforathe;11fe offthelplant Rislacceptable.,
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- e (The NRCistafflhasiassistedfinithe preparation'ofgthis TER and?endorsesnit?
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n CONCLUSIONS y
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JTheis'tAfficoncludesLthat LP&Li(1)3 asisstisfActbrily compidt'eU sheiconfirR h t m.
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?matory? analyses. program l demonstrating"theTadequacy ofjtheibasemat a_nd1(2)5 ?
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hasLinstitutedfan. acceptable basemat' surveillance program,qbothiasfrequiredi
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E byJ License ConditionL2.C.-17^6ff theWaterford'3; operating;1icense.,iThis t sissuetis," therefore, considered *to'be closed.5
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' Principal Condibufor:
5lH. Wilson
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~ Dated:
0ctober. 27,1987s l)5 h
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