ML17334B468
| ML17334B468 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 02/28/1993 |
| From: | CHICOTS J M, MEYER T A WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| To: | |
| Shared Package | |
| ML17331A266 | List: |
| References | |
| WCAP-13517, NUDOCS 9304150164 | |
| Download: ML17334B468 (30) | |
Text
~vvWCAP-13517 WESTINGHOUSE PROPRIETARY CLASS3ATTAc//gEwlgEVALUATION OFPRESSURIZED THERMALSHOCKFORD.C.COOKUNIT2J.M.ChicotFebruary199AMERICANELECTRICPOWERSERVICECORPORATION APPROVEDINGENERAL0APPROVEDEXCEPTASNOTEDE3NOTAPPROVED0FORREFERENCE ONLYBYm'rikd~DATEWorkPerformed UnderShopOrderAFFP-108PreparedbyWestinghouse ElectricCorporation fortheIndianaMichiganPowerCompanyApprovedby:T.A.Meyer,ManagerStructural Reliability 8PlantLifeOptimization WESTINGHOUSE ELECTRICCORPORATION NuclearandAdvancedTechnology DivisionP.O.Box355Pittsburgh, Pennsylvania 15230-0355 41993Westinghouse ElectricCorporation AllRightsReserved TableofContentsListofTablesListofFiguresTABLEOFCONTENTS~PaeIntroduction Pressurized ThermalShockMethodsofCalculation ofRTPTSVerification ofPlant-Specific MaterialProperties NeutronFluenceValuesDetermination ofRTPTSValuesforAllBeltlineRegionMaterials Conclusions References 13 TableLISTOFTABLESTitlePacae1.D.C.CookUnit2ReactorVesselBeltlineRegionHaterialProperties 2;NeutronExposureProjections atKeyLocations intheD.C.CookUnit2PressureVesselClad/Base HetalInterface for8.65and32EFPY3.Calculation ofChemistry FactorsUsingD.C.CookUnit2Surveillance CapsuleData104.RTPTSValuesforD.C.CookUnit2for8.65EFPY5.RTPTSValuesforD.C.CookUnit2for32EFPY12~iciureLISTOFFIGURESTitle~Pae1.Identification andLocationofBeltlineRegionHaterials fortheD.C.CookUnit2ReactorVesselN2.RTPTSversusFluenceCurvesforD.C.CookUnit2LimitingHaterials
-Intermediate ShellPlate,C5556-213 INTRODUCTION Alimitingcondition onreactorvesselintegrity knownasPressurized ThermalShock(PTS)mayoccurduringaseveresystemtransient suchasaLoss-Of-Coolant-Accident (LOCA)orasteamlinebreak.Suchtransients maychallenge theintegrity ofareactorvesselunderthefollowing conditions:
severeovercooling oftheinsidesurfaceofthevesselwallfollowedbyhighrepressurization; significant degradation ofvesselmaterialtoughness causedbyradiation embrittlement; andthepresenceofacritical-size defectinthevesselwall.In1985theNuclearRegulatory Commission (NRC)issueda=formalrulingonPTS.Itestablished screening criteriaonpressurized waterreactor(PWR)vesselembrittlement asmeasuredbythenil-ductility reference temperature, termedRTPTS.RTPTSscreening valuesweresetfor[$1beltlineaxialwelds,forgingsorplatesandforbeltlinecircumferential weldseamsforend-of-license plantoperation.
Thescreening criteriaweredetermined usingconservative fracturemechanics analysistechniques.
AllPWRvesselsintheUnitedStateshavebeenrequiredtoevaluatevesselembrittlement inaccordance withthecriteriathroughend-of-license.
TheNRChasamendeditsregulations forlightwaternuclearpowerplantstochangetheprocedure forcalculating radiation embrittlement.
TherevisedPTSRulewaspublished intheFederalRegister, May15,1991withaneffective dateofJune14,1991~~.Thisamendment makestheprocedure forcalculating RTPTSvaluesconsistent withthemethodsgiveninRegulatory Guide1.99,Revision'~
~.
Thepurposeofthisreportistodetermine theRTPTSvaluesforthe0.C.CookUnit2reactorvesseltoaddresstherevisedPTSRule.Section2discusses theRuleanditsrequirements.
Section3providesthemethodology forcalculating RTPTS.Section4providesthereactorvesselbeltlineregionmaterialproperties forthe0.C.CookUnit2reactorvessel.Theneutronfluencevaluesusedinthisanalysisarepresented inSection5.TheresultsoftheRTPTScalculations arepresented inSection6.Theconclusions andreferences forthePTSevaluation followinSections7and8,respectively.
2.PRESSURIZED THERMALSHOCKThePTSRulerequiresthatthePTSsubmittal beupdatedwhenevertherearechangesincoreloadings, surveillance measurements orotherinformation thatindicates asignificant changeinprojected RTPTSvalues.TheRuleoutlinesregulations toaddressthepotential forPTSeventsonpressurized waterreactorvesselsinnuclearpowerplantsthatareoperatedwithalicensefromtheUnitedStatesNuclearRegulatory Commission (USNRC).PTSeventshavebeenshownfromoperating experience tobetransients thatresultinarapidandseverecooldownintheprimarysystemcoincident withahighorincreasing primarysystempressure.
ThePTSconcernarisesifoneofthesetransients actsonthebeltlineregionofareactorvesselwhereareducedfractureresistance existsbecauseofneutronirradiation.
Suchaneventmayresultinthepropagation offlawspostulated toexistneartheinnerwallsurface,therebypotentially affecting theintegrity ofthevessel.TheRuleestablishes thefollowing requirements foralldomestic, operating PMRs:*Allplantsmustsubmitprojected valuesofRTpTSforreactorvesselbeltlinematerials bygivingvaluesfortimeofsubmittal, theexpiration dateoftheoperating license,andtheprojected expiration dateifachangeintheoperating licenseorrenewalhasbeenrequested.
Thisassessment mustbesubmitted withinsixmonthsaftertheeffective dateofthisRuleifthevalueofRTPTSforanymaterialisprojected toexceedthescreening criteria.
Otherwise, itmustbesubmitted withthenextupdateofthepressure-temperature limits,orthenextreactorvesselsurveillance capsulereport,orwithin5yearsfromtheeffective dateofthisRulechange,whichever comesfirst.Thesevaluesmustbecalculated basedonthemethodology specified inthisrule.Thesubmittal mustincludethefollowing:
I)thebasesfortheprojection (including anyassumptions regarding coreloadingpatterns),
and2)copperandnickelcontentandfluencevaluesusedinthecalculations foreachbeltlinematerial.
(Ifthesevaluesdifferfromthosepreviously submitted totheNRC,'justification mustbeprovided.)
- TheRTPTS(measureoffractureresistance) screening criteria'forthereactorvesselbeltlineregionis270'Ffor,plates,forgings, axialwelds;and,300Fforcircumferential weldmaterials.
- Thefollowing equations mustbeusedtocalculate theRTPTSvaluesforeachweld,.plateorforginginthereactorvesselbeltline:
EquationI:RTPTSI+H+hRTPTSEquation2:hRTPTS(CF)f(0.28-0.10 logf)*AllvaluesofRTPTSmustbeverifiedtobeboundingvaluesforthespecificreactorvessel.Indoingthiseachplantshouldconsiderplant-specific information thatcouldaffectthelevelofembrittlement.
- Plant-specific PTSsafetyanalysesarerequiredbeforeaplantiswithin3yearsofreachingthescreening
- criteria, including
.analyses'f alternatives tominimizethePTSconcern.*NRCapprovalforoperation beyondthescreening criteriaisrequired.
3~METHODFORCALCULATION OFRTPTSInthePTSRule,theNRCStaffhasselectedaconservative anduniformmethodfordetermining plant-specific valuesofRTPTSatagiventime.Forthepurposeofcomparison withthescreening
- criteria, thevalueofRTPTSforthereactorvesselmustbecalculated foreachweldandplateorforginginthe.beltline regionasfollows.RTPTS+H+~PTSwherehRTPTS(CF)f('Initialreference temperature (RTNDT)in'Foftheunirradiated materialMMargintobeaddedtocoveruncertainties inthevaluesofinitialRTNDT,copperan'dnickelcontents, fluencearidcalculational procedures.
H-66'Fforweldsand48'FforbasemetalifgenericvaluesofIareused.H=56'Fforweldsand34'FforbasemetalifmeasuredvaluesofIareused.fNeutronfluence,n/cm2(E>1HeVattheclad/base metalinterface),
dividedby10CFChemistry factorfromtables~2~
forweldsandforbasemetal(platesandforgings).
Ifplant-specific surveillance datahasbeendeemedcredibleperReg.Guide1.99,Rev.2~~,itmaybeconsidered inthecalculation ofthechemistry factor.
VERIFICATION OFPLANT-SPECIFIC HATERIALPROPERTIES Beforeperforming thepressurized thermalshockevaluation, areviewofthelatestplant-specific materialproperties wasperformed.
ThebeltlineregionisdefinedbythePTSRule~2~tobe"theregionofthereactorvessel(shellmaterialincluding welds,heataffectedzonesandplatesorforgings) thatdirectlysurrounds theeffective heightoftheactivecoreandadjacentregionsofthereactorvesselthatarepredicted toexperience sufficient neutronirradiation damagetobe'onsidered intheselection ofthemostlimitingmaterialwithregardtoradiation damage."FigureIidentifies andindicates thelocationofallbeltlineregionmaterials fortheD.C.CookUnit2reactorvessel.Haterialpropertyvalueswereobtainedfrommaterialtestcertifications fromtheoriginalfabrication aswellastheadditional materialchemistry testsperformed aspartofthesurveillance capsuleprogram~~.Theaveragecopperandnickelvalueswerecalculated foreachofthebeltlineregionmaterials usingalltheavailable materialchemistry information.
Asummaryofthepertinent chemicalandmechanical properties ofthebeltlineregionplateandweldmaterials oftheD.C.CookUnit2reactorvesselaregiveninTablel.AlloftheinitialRTNDTvalues(I-RTNDT) arealsopresented inTablel.
C5521-24JICiVJCZ!LalI27010'8010'0'5556-2 CORE0~C5540-2270'0'CC)180'5592-1 Figurel.Identification andLocationofBeltlineRegionMaterials fortheD.C.CookUnit2ReactorVessel I
TABLE1D.C.COOKUNIT2REACTORVESSELBELTLINEREGIONMATERIALPROPERTIES MaterialDescriptionCU(>)NI(%%d)I-RTNDT('F)Intermediate Shell,C5556-20.15Intermediate Shell,C5521-2*0.1250.570.585838LowerShell,C5540-2LowerShell,C5592-1Longitudinal'elds
- Circumferential Weld*0.110.140.0520.0520.640.590.9670.967-20-20-35-35*Meanvaluesofcopperandnickelasindicated belowMaterialPlate,C5521-2DataSourceOriginalHillTestReportSurveillance Program[5]MeanvalueCopper~wt.t',0.14O.ll0.125Nickel~wt.I0.580.580.58WeldOriginalMillTestReportSurveillance Program[5]Surveillance Program[5]Meanvalue0.050.0550.050.970.970.960.0520.967 5.NEUTRONFLUENCEVALUESThecalculated fastneutronfluence(E>1MeV)attheinnersurfaceoftheD.C.CookUnit2reactorvesselisshowninTable2.Thesevalueswereprojected usingtheresultsoftheCapsuleUradiation surveillance program~"~.
TABLE2NEUTRONEXPOSUREPROJECTIONS*
ATKEYLOCATIONS INTHED.C.COOKUNIT2PRESSUREVESSELCLAD/BASE METALINTERFACE FOR8.65AND32EFPY[IEFPY8.65320~0.1790.66310'.2440.90230'.3091.140.4651.71*F1uencex10n/cm(E>1.0MeV)
6.DETERMINATION OFRTPTSVALUESFORALL8ELTLINEREGIONMATERIALS Usingtheprescribed PTSRulemethodology, RTPTSvaluesweregenerated forallbeltlineregionmaterials ofthe0.C.CookUnit2reactorvesselasafunctionofpresenttime(8.65EFPYperCapsuleUanalysis) andend-of-license 32EFPY)fluencevalues.Thefluencedataweregenerated basedonthemostrecentsutveillance capsuleprogramresults~"~.
ThePTSRulerequiresthateachplantassesstheRTPTSvaluesbasedonplantspecificsurveillance capsuledataundercertainconditions.
Theseconditions are:Plantspecificsurveillance datahasbeendeemedcredibleasdefinedinRegulatory Guide1.99,Revision2,andRTPTSvalueschangesignificantly.
(ChangestoRTPTSvaluesareconsidered significant ifthevaluedetermined withRTPTSequations (I)and(2),orthatusingcapsuledata,orboth,exceedthescreening criteriapriortotheexpiration oftheoperating license,including anyrenewedterm,ifapplicable, fortheplant.)ForD.C.CookUnit2,theuseofplantspecificsurveillance capsuledataarisesfortheintermediate shellplate,C5521-2andtheweldsbecauseofthefollowing reasons:I)Therehavebeenthreecapsulesremovedfromthereactorvessel,andthedataisdeemedcredibleperRegulatory Guide1.99,Revision2.2)Thesurveillance capsulematerials arerepresentative oftheactualvesselmaterials.
Thechemistry factorsfortheintermediate shellplate,C5521-2andweldswerecalculated usingthesurveillance capsuledataasshowninTable3.Allotherchemistry factorvaluesfortheremaining beltlinematerials werecalculated usingtheTablesIand2fromRegulatory Guide1.99,Revision2.
TABLE3CALCULATION OFCHEMISTRY FACTORSUSINGD.C.COOKUNIT2SURVEILLANCE CAPSULEDATA~~Carponent CaPsuleFLuenceFFDRTNDTFPDRTNDT(FF)"2Intermediate ShellPLateC5521-2(Long.)intermediate ShellPlateC5521-2(Trans.)0.2640.6831.061.580.2640.6831.061.580.6380.8931.0161.1260.63S0.8931.0161.126559095958010010313835.07280.37896.548107.00451.01389.309104.679155.4380.4070.7981.0331.2690.4070.7981.0331.269719.4427.012Chemistry Factor~719.442/7.012i102.61MeldMetalT0.2640.638'T0.6830.893X1.061.016U1.581.1264050707525.50744.65571.14184.4770.4070.7981.0331.269225.7793.506Chemistry Factor~225.779/3.506~64.40 Tables4and5provideasummaryoftheRTPTSvaluesforallbeltlineregionmaterials for8.65EFPYandend-of-life (32EFPY),respectively, usingthePTSRule.TABLE4RTPTSVALUESFORD.C.COOKUNIT2FOR8.65EFPYHaterialhRTgpT('F)
+InitialRTNOT+Ha>ginRTPTS(CFxFF*)('F)('F)(F)Intermediate ShellPlate,C5556-2Intermediate Shell.Plate,C5521-2LowerShellPlate,C5540-2LowerShellPlate,C5592-1Intermediate ShellLongitudinal WeldsLowerShellLongitudinal WeldsCircumferential MeldSeam108.350.78786.500.787(102.61)0.78774.600.78799.550.78770.80'0.618(64.40)0.61870.800.543(64.40)0.54370.800.787(64.40)0.787583838-20-20-35-35-35-35-35-353434343434565656565656177140(153)7392656160567772()Indicates numberswerecalculated usingsurveillance capsuledata.*Fluencefactorbaseduponpeakinnersurfaceneutron.fluenceof4.65x10n/cm[4],exceptforthelongitudinal welds.Fortheintermediate shelllongitudinal welds,thefluencefactorisbasedona,neutronfluenceof2.44x10n/cm[4]attheinnersurfaceoftheweldatthe10'ocation.
Forthelowershelllongitudinal welds,thefluencefactorisbasedonaneutronfluenceof1.79x10n/cm[4]attheinnersurfaceoftheweldatthe0'ocation.
P0 TABLE5RTPTSVALUESfORD.C.COOKUNIT2FOR32EFPYMaterialhRTNDT('F)
'InitialRTNDT+(CFxFF*)('F)MarginRTPTS('F)('F)Intermediate ShellPlate,C5556-2Intermediate ShellPlate,C5521-2LowerShellPlate,C5540-2LowerShellPlate,C5592-1Intermediate.
ShellLongitudinal Welds108.351.14886.501.148(102.61)1.14874.601.14899.551.14870.800.971(64.40)0.971583838-20-20-35-353434345656216171(190)1001289085LowerShellLongitudinal WeldsCircumferential WeldSeam70.80(64.40)70;80(64.40)0.8850.8851.1481.148-35-35-35-3556565656847810295()Indicates numberswerecalculated usingsurveillance capsuledata.*Fluencefactorbaseduponpeakinnersurfaceneutronfluenceof1.71x10n/cm[4],exceptforthelongitudinal welds.Fortheintermediate shelllongitudinal welds,thefluencefactorisbasedonaneutronfluenceof9.02x10n/cm[4]attheinnersurfaceoftheweldatthe10location.
Forthelowershelllongitudinal welds,thefluencefactorisbasedonaneutronfluenceof6.63x10n/cm[4]attheinnersurfaceoftheweldatthe0'ocation.
gl7.CONCLUSIONSIAsshownsnTables4and5,alltheRTPTSvaluesremainbelowtheNRCscreening valuesforPTSusingthefluencevaluesforthepresenttime(8.65EFPY)andtheprojected fluencevaluesfortheend-of-life (32EFPY).AplotoftheRTPTSvaluesversusthefluenceisshowninFigure2forthemostlimitingmaterial, theintermediate shellplate,C5556-2intheD.C.CookUnit2reactorvesselbeltlineregion.300250200LI0M150t-CLCC100SCREENING CRITERIA~~~~~~~~~~~~~~~0~~~~~~~....k"~~~~~~~~~~~~~.0'"~~~~~~~~~~~~~~~~508.65EFPY432EFPY1E+182E+'I83E+185E+181E+192E+193E+195E+19FLUENCE(NEUTRONS
/CM)INTER.SHELLPIATE,C5556-21E+20Figure2.RTPTSversusFluenceCurvesforD.C.CookUnit2LimitingMaterial-Intermediate ShellPlate,C5556-2 eglJ REFERENCES
[1]10CFRPart50,"Analysis ofPotential Pressurized ThermalShockEvents,"July23,1985.[2]10CFRPart50,"Fracture Toughness Requirements forProtection AgainstPressurized ThermalShockEvents,"May15,1991.(PTSRule)[3]Regulatory Guide1.99,Revision2,"Radiation Embrittlement ofReactorVesselMaterials,"
U.S.NuclearRegulatory Commission, May1988.[4]WCAP-13515, "Analysis ofCapsuleUfromtheIndianaMichiganPowerCompanyD.C.CookUnit2ReactorVesselRadiation Surveillance Program,"
page6-28,J.M.Chicots,etal.,October1992.(Westinghouse Proprietary Class3)[5]WCAP-8512, "American ElectricPowerCompanyDonaldC.CookUnitNo.2ReactorVesselRadiation Surveillance Program",
J.A.Davidson, etal.,November1975.[6]MT/SMART-090(89),
"D.C.CookUnit2ReactorVesselHeatupandCooldownLimitCurvesforNormalOperation",
N.K.Ray,April1989,Tablel.
ENCLOSURE 2TOAEP:NRC:1173C MARKUPOFPRESSURIZED THERMALSHOCKANDUPPERSHELFENERGYSUMMARYTABLES Enclosure.2 toAEP:NRCall73" SucTRaryFileforPressurized TheraalShackPLantNaaa0CCock1EOLa}0/25/2014$eltL}rident.Na-LeShell$445Mat"LeShelL$4405.2Mc-LeShelL$4'053MeetXc.ident.C3$n}0XeutfLuenceat.ER/EFPT1ehkfc&l.lOc181ehhakh0'4'FiLO'E}g~9840-F1I}OE}9XethcdofOetarein.
}RTXTEXS-ZXtaS-2NTH5.Zthaaiatry factorXechadofDeterge}n CFTableTabLeTable0.140.}40.460.'50.4Sint.SheLL~>>-Iint.SheLL$4'06-2int.Shell$4406-3LeverShelL$44071LoverSheLL5447.2LoverSheLL$4407.31.41E191.41E191.41E191.4}E19141E191.41E19SOP33'F40'F'2$'F-1Z'F3S'FPlantSaecificPlantScecificPlantSoecificPlantSpecificPlantSpecificPlantSpecific$1.4104,5102.9495.5TabL~Tabl~Calmlatad TableTab'LeTable0.120.150.150.140120140.520.500.490550.590.50Xa='.eSheL}.AxialVeLda1-4-2A1(.'c-'.e/int.ShelLC}rc.Velds-c'z13Z53and12OCS(T)202918.56'F1.NK15-56'Fi'0'E1$CenericCeneric206,4TableTableD,ZS0.350.7>>O.i>>tpLnttoLoverShellCirc.Veld9-4'21P35711.4}E19'-56'FCeneric219TableQ.7'n.ShelLAxialVe}d2-4'A/CLoverShellAxialVeld3-4'ZA/C13Z53120~&(T)13Z53and12OCS(T)56'FOqor=14~QZ-S&F0clcj,1RCcnericCenericZO&.4206.4TableTableQe278' SumitaryFileforPressurized TheraalShockPlantNaekeBeltlineIdent.HeatNoIdent.IONeut.FLuenceatEOLIEFPTIRTHethodofOetenafn.
IRTChosistryFactorH<<thodofOetanafn.
CFC.C.Caak'IALLdataexceptaanotedbelowwrefreretheJulyG,1992LetterfrereE.E.Ffapatrfck:to T.E.Hurley,"OanaLdC.CookNuclearPLantUnits1and2...genericI.atter92-0t,Revfaian1,ReactarVesselgtruceuaL Integrity."
Information regarding chersfcaL ccapoaftfcn, initialRT,andaethodalagy ofdetemfnatfan farthelIJSEfor'hewidearefreretheNovedaer29,1993LetterfreeE.E.Ffttpatrfck toT.E.Hurley,eganaldC.CookNuclearplantUnits1ard2...ResponsetaRequestforNitfanalInfonaatian fargenerfcletter92-OtRevisicnt."NovaluefarICuafveld5-442@aspravided, therefore thedefaultvalueof0.35NasUsed.DatLd, SumaryFileforPressurized ThermalShockPlantXaaaO.C.Cook2EOL:12/23/2017Beltlfneident.int.SheLL10-1int.Shell10-2LrwerShell9-1Lo~erSheLL9-2int.ShelLAxialVeldsL~rShellAxial'MeldsCfrcus.'MeldHeatXo.ident.C5556-205521-2C55402C5592-153986S398610Xeut.FluenceatEOLIEFPY'1.71E191.71E19~~0<iViEl+9.0ZE186.63E18171E1958'F'8'F20'F20'F-35'F.35'F-35'FXethodofOeterain.
LRTPlantSoecificPlantSpecificPlantSpecificPlantSpecificPlantSpecificPlantSpecificPlantSoecificChemistry Factor108.910Z.6174.664.464.4methodofOeterain.
CFTableCalculated TableTabl~Calculated CaLculated Calculated0.15O.LZ,S0.110.140.050.050.050.$)0.580.640.970.970.97~RAinitiaLRTandchcceicsL ccapositicn fortheplatesandarefreetheJuly13,1992letterfrommE.E...Fit~trick toT.E.Hurley,"OcnaldC.CookXuclearPlantUnits1arxl2...GenericLetter92-01,Revision1,ReactorVesselS'tructuraL integrity."
Updatedflvences, chemicalccaposition, initialRT,andcalculated chesistry factorsarefreetheApril12,1993letterfrcceE.E.Fit-patrick toT.E:Hurley,CcnaldC.CookXu=learplantUnitZ...Updated Reference TeeperaureandPressurized The~iShockAnalyses."
1>
~~~i)1l~~%~~C~TC',.'~eL,I,,~~4'C',,~RtWRSl%tI8 SLfmflary FileforUpperShelfEnergyPLantNateBeltlfneident.HeatNo.Natarial1/4TUSEacEOL1/4TXeutranFluenceatEOLUnirred.USEHethadofDetermfn.
Unirrad.USE~RfoneD.C.CaakLAlldata'xŽcapt asnotedbalanuerefrcatheJuly13,1992LetterfreeE.E.Flttpatrfck taT.E.Hurley,49onaldC.CookNuclearPlantUnits,'1and2...GenericLetter92-0t,Revision1,ReactorVesseLStructuraL integrity."
"Infarnatfon regardfng WSEandeethodalogy ofdetersinatfcn fortheLOSEfarthemfdsarefrytheXavier29,1993LetterfrcaE.E.Fit~trick toT.E.Hurley,DonaldC.CookNuclear'PlantUnits1and2...ResponsetoRequestforAhfftfcnal fnfomatfan forGcnerfcLetter92.01,Revisicn1.5O8~~used'he LJJSEvaluesfarsidst-442,2-442and3442represent theNRCstaffcalculated averageofD.C.CaakandSfstarPLantdata<NcGufre, Unit1andDiabloCanyon,Unit2)forveLdufreheatscontaining heatnas.13253andf20'.TheNSEfaruelds9-44ZfsfreeMCAP.12519, "Analysis oftheNafneYankeeReactorVesselSecondMattCapsulelocatedat253',"Narch1991.TheQJSEforzelda0-442fafreeCAP.10756, theReportforSurvefLlance Capauf~UfreeNcafreUnitt.
~~III'CI~ItI~aI'tt:..ISII~a'L;~~S'L~RMR55~RR~'I~~~III r.".'J~e-IIPt4'