ML17254A294

Responds to NRC Request for Review of Certain Concerns Re Exxon Nuclear Corp ECCS Evaluation Model.Based on Listed Review W/Exxon & Westinghouse,Stated Concerns Inapplicable to Facility

ML17254A294
Person / Time
Site:	Ginna
Issue date:	03/26/1985
From:	KOBER R W ROCHESTER GAS & ELECTRIC CORP.
To:	ZWOLINSKI J A Office of Nuclear Reactor Regulation
References
NUDOCS 8504030076
Download: ML17254A294 (5)

Text

REGULATORYFORMATIONDISTRIBUTIONSM(RIDS)

SUBJECT:

RespondstoNRCr'equestforreviewofcertainconcernsreExxonnuclearCor'pECCSevaluationmodelsBasedonlistedrevieww/Exxon8'riestinghouse<statedconcernsinapplicabletofacility,SIZE:DISTRIBUTIONCODE+A001DCOPIESRECEIVED:LTRENCLTITLE:ORSubmittal:GeneralDistributionACCESSIONNBR;8504030076DOC~DATE:85/03/26NOTARIZED;NODOCKETFACIL:50244RobertEmmetGinnaNuclearPlantgUnitiiRochesterG05000244AUTHINANE'UTHORAFFILIATIONKOBERgR,HERochesterGas8ElectricCorp.RECIP~NAME>>RECIPIENTAFFILIATIONZNOLINSKI'iJ.AOperatingReactorsBranch5NOTES;NRR/DL/SEP1cy,OL:09/19/6905000244RECIPIENTIDCODE/NAME'RRORB5BC01INTERNAL:ACRS'9ELD/HDS4NRR/DLDIRNRR/DL/TSRG.NRR/DSI/RABRGN1COPIESLTTRENCL7611111RECIPIENTIDCODE/NAMEADM/LFMBNRR/DE/MTEBNRR/Dl/ORABETBREFILE04COPIESLTTRENCLEXTERNAL:EGSGBRUSKE,SNRCPDR02NOTES:LPDRNSIC0305TOTALNUMBEROFCOPIESREQUIRED:LTTR28ENCL H(IIIII~~'IlgllI'Pt~

t///////////////////////////II/El)7/IIII//////8'vis//ROCHESTERGASANDIstAtCELECTRICCORPORATIONo69EASTAVENUE,ROCHESTER,N.Y.14649-0001ROGERtN.KOBERVICePRESIDSNTELECTRIC6STEAMPttODVCTIONMarch26>1985TSI.CPHONCARCACODETld546-2700DirectorofNuclearReactorRegulationAttention:Mr.JohnA.Zwolinski>ChiefOperatingReactorsBranchNo.5U.S.NuclearRegulatoryCommissionWashington<D.C.20555

Subject:

LossofCoolantAccidentAnalysisR.E.GinnaNuclearPowerPlantDocketNo.50-244

DearMr.Zwolinski:

ThisletterisinresponsetoarequestfrommembersoftheNRCstafftoaddresscertainconcernsregardingExxonNuclearCorporation's(ENC)emergencycorecoolingsystemevaluationmodel.WehavereviewedtheseconcernswithExxonNuclearandwithourcurrentfuelvendorandcoredesignerWestinghouseElectricCorporationand>asdescribedbelow<havereachedtheconclusionthatthestatedconcernsarenotapplicabletoGinnaFrom1978through1983>GinnareloadfuelwassuppliedbyENC.ThemostrecentENClossofcoolantaccidentanalysisforGinnawasperformedinSpring1982andwassubmittedtotheNRCwithourletterdatedAugust9<1982.Thatanalysisresultedinacalculatedpeakcladtemperature(PCT)of1928F.ENChasconfirmedtousthatthespecificmodelsusedfortheGinnaanalysisdidnotcontainanyofthethreeerrorswhichtheNRCStaffhasidentifiedtousregardingheattransfercorrelationsandaugmentationfactorsandmixingassumptions.RegardingthefourthconcernraisedbytheNRCStaff>thefollowingbackgroundinformationandconclusionsareprovided.In1984<RG6EbeganatransitiontoWestinghousefuel.IntheanalysisperformedbyWestinghouseforthattransition<theyevaluatedtheplantresponsetoalltransientswhichmaybeaffectedbyfueltype>includingthelossofcoolantaccident.Westinghousewasprovidedwithdetailedfuelparameterssuchasdimensions>densitiesandenrichments.WestinghouseperformeddetailedpressuredropmeasurementsonWestinghouseoptimizedfuelassembly(OFA)designfuelandENCfuelassemblies.WestinghouseconcludedthatanalyzingacompletecoreofOFAunderLOCAconditionswasconservativewithrespecttoanypotentialcombinationandconfigurationofWestinghouseandENCassemblytypes.TheassumptionofmodelingafullcoreofOFAwasdeterminedtobeconservativefortransitioncyclesfortwomajorreasons:8504OSOO7S850S2SlPDRADOCK05000244PPDRADO),)O ROCHESTERGASANDELECTRICCORP.DATEMarch26>1985TOMr.JohnA.ZwolinskiSHEETNO.2TheincreaseincoreflowareaassociatedwithOFAduetothesmallerroddiameterhasanimportantimpactonfloodingratesduringreflood.AfullOFAcoreconfigurationdecreasescorefloodingrateswhichreducesheattransfercoefficientsandresultsinearliersteamcooling.2.TheOFAhasahighervolumetricheatgenerationratethantheENCfuel.Theanalysisassumestha'tanOFAassemblyhasthehottestrodandmaximumFHwhichmaximizesthecalculatedPCT.Westinghousealsoevaluatedtheimpactofanyhydraulicresistancedifference.TheonlyportionoftheLOCAevaluationmodelimpactedbythesmallhydraulicresistancedifferencewhichexistsbetweentheENCandOFAfuelisthecorerefloodtransient.Sincethehydraulicmismatchissosmall>onlycrossflowsduetosmallerrodsizeandgriddesignsneedtobeevaluated.ThemaximumrefloodaxialflowreductionfortheOFAatanypossiblepeakcladtemperaturelocationinthecore<resultingfromcrossflowstoadjacentENCassemblies<hasbeenconservativelycalculatedtobeonepercent.AnalyseswereperformedwhichdemonstratedthatthemaximumPCTpenaltypossibleofOFAfuelduringthetransitionperiodis4F.Afterthistransition>the0WestinghouseECCSanalysiswillapplytoafull-coreOFAwithoutthecrossflowpenalty.Inadditiontothefactorsidentifiedabove<theburnuplevelsand/orpowerlevelsoftheENCfuelfurtherassurethatthelimitingfuelistheOFAfuel.ThelastregionofENCfuelwasloadedin1983.Fourofthesefuelassemblieshaveburnupsofatleast11,000MWD/MTU<whiletheotherassembliesinthisregionhaveburnuplevelsinexcessof20>000MWD/MTU.EightfreshENCfuelassemblieswereloadedduringtheSpring1984refuelingout-ageandcurrentlyhaveburnupsinexcessofll>000MWD/MTU.Maxi-mumburnupswillremainbelowthedesignlimitsestablishedbyENC.TheENCassembliesarenotlocatedinpeakpowerlocationsforCycle15buthaveFvaluesatleast5%belowthatinthelimitingOFAlocations.TheminimummargintotheFlimitpre-0dietedforanENCassemblyoccursatanelevationwheretheFlimitis2.29andthepredictedFis2.125.Itshouldben8tedthatthisvalueispredictedb2sedonloadfollowoperation<whileGinnatypicallyoperatesbaseloaded.AsdescribedinourletterdatedApril10<1984<wehaveloadedfourENCannularfuelpelletdemonstrationassembliesduringthecurrentCycle14-15refuelingoutage.Inadditiontothefueltemperatureandstoredenergybenefitswhichderivefromtheuseofanannularfuelpellet,theseassembliesareloadedinthecoreperipheryandhaveassemblypowerlevelslessthan0.8timescoreaveragepower.TheseassemblieshavebeenexplicitlymodeledinthemostrecentWestinghousereloadanalysis.Thus>theseassembliesalsoareboundedbytheOFAfuelanalysis.

ROCHESTERGASANPELECTRICCORP.pATENarch26,l985ToNr.JohnA.zwolinskiSHEETNO.ForthereasonsstatedaboveiwehaveconcludedthattheanalysesperformedbyWestinghousewiththeapprovedWestinghouseevaluationmodelsboundallfuelcurrentlyloadedintheGinnareactor.ThisevaluationdemonstratesthatthelimitingfueltypeistheWestinghouseOFAfuel.Thus<norelianceiscurrentlymadebytheENCLOCAmodelsandpotentialconcernsregardingthosecodesdonotapplytoGinna.ytrulyyoursiRogerW.Kober