ML17264A824
| ML17264A824 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 02/10/1997 |
| From: | MECREDY R C ROCHESTER GAS & ELECTRIC CORP. |
| To: | VISSING G S NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-M97313, NUDOCS 9702200011 | |
| Download: ML17264A824 (13) | |
Text
CATEGORYj.REUULATOINPORNATZONDISTRIBUTION+TEN(RIDE)ACCESS1,0k!.NPP:,9702200011DOC.DATE:97/02/10NOTARIZED:NODOCKETFACIL:'.IO-244Rober'tEmmetGinnaNuclearplant,Unit1,RochesterG05000244AUTH.N~MRAUTHORAFFILIATIONMECREDK,R.C.RochesterGas6ElectricCorp.RECIP.NAMERECIPIENTAFFILIATIONVISSING,G.S.
SUBJECT:
Requestsexemptionto10CFR50.60touseASMECodeCaseN-514indeterminationofLTOPenabletempinplaceofmethodologycurrentlyrequiredby10CFR50.60.DISTRIBUTIONCODE:A047DCOPIES'RECEIVED:LTRLENCLIISIZE:TITLE:ORSubmittal:Inservice/Testing/RelieffromASMECode-GL-89-04TNOTES:LicenseExpdateinaccordancewithlOCFR2,2.109(9/19/72).05000244E,RECIPIENTIDCODE/NAME'PD1-1LAVISSING,G.INTERNAL:AEOD/SPD/RABNRR/DE/EMEBOGC/HDS3RES/DET/EMMEBEXTERNAL:LITCOANDERSONNRCPDRCOPIESLTTRENCL1111111110111111RECIPIENTIDCODE/NAME,PD1-1PDBILE.CENTE~R01NUDOCS-ABSTRACTRES/DET/EIBZNOACCOPIESLTTRENCL11111111,11DUENOTETOALL"RIDS"RECIPIENTS:PLEASEHELPUSTOREDUCEWASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMOWFNSD-5(EXT.415-2083)TOELIMINATEYOURNAMEFROMDISTRIBUTIONLISTSFORDOCUMENTSYOUDON'TNEED!TOTALNUMBEROFCOPIESREQUIRED:LTTR13ENCL12 ANDROCHESTERGASANDEtECTR1CCORRORAT1ON~89FASTAYENUE,ROCHESTER,N.Y14649-0001ARFACODE7165'-2700ROBERTC.MECREDYVicePresidentNvcleorOperotionsFebruary10,1997U.S.NuclearRegulatoryCommissionDocumentControlDeskAttn:GuyS.VissingProjectDirectorateI-1Washington,D.C.20555,
Subject:
RequestforExemptionto10CFR50.60touseAmericanSocietyofMechanicalEngineers(ASME)CodeCaseN-514intheDeterminationofLowTemperatureOverpressureProtection(LTOP)EnableTemperatureRochesterGas&ElectricCorporationR.E.GinnaNuclearPowerPlantDocketNo.50-244
References:
(a)LetterfromR.C.Mecredy,RG&E,toG.S.Vissing,NRC,RequesttoUseASMECodeCaseN-514intheDeterminationofLovttTemperatureOverpressureProtection,datedDecember18,1996.(b)LetterfromG.S.Vissing,NRC,toR.C.Mecredy,RG&E,R.EGinna-AcceptanceofRequesttoExtendTimeforApprovalofRevisionofPressureandTemperatureLimitsReport(PTLR)(TACNo.M97313),datedDecember10,1996.
DearMr.Vissing:
ByReference(a),RG&Erequestedper10CFR50.55a(a)(3)tousetheASMESectionXICodeCaseN-514inlieuof10CFR50,60forcalculatingtheLTOPenabletemperature.UponfurtherconsultationwithNRCStaff,RG&Ewasaskedtosubmitthisrequestasanexemptioninaccorandancewith10CFR50.12.Therefore,includedasAttachmentItothisletterisarequestforexemptionperthecriteriaof10CFR50.12(a)(2)(iii).ThisrequestistoallowuseofASMECodeCaseN-514,"LowTemperatureOverpressureProtectionSectionXI,Division1"(seeAttachmentIl)inthedeterminationoftheLTOPenabletemperatureinplaceofthemethodologycurrentlyrequiredby10CFR50.60.Therefore,thisdocumentsupercedesthatprovidedinReference(a)initsentirety.97022000ii970210PDRADQCK05000244PPDR
'I4If'WP ThecodecasehasbeenapprovedbytheASMEbasedonconservatismsalreadyincludedwithintheLTOPsetpointcalculations.ApprovalofthisexemptionrequestisrequiredbyMay1,1997inordertosupportissuanceofarevisedPTLRbyJuly1,1997perReference(b).PleasecontactGeorgeWrobel,ManagerofNuclearSafetyandLicensingat(716)724-8070ifyouhavefurtherquestions.Verytrulyyours,RobertC.MecredyMDFi903Attachmentsxc:U.S.NuclearRegulatoryCommissionMr.GuyS.Vissing(MailStop14C7)PWRProjectDirectorateI-1Washington,D.C.20555U.S.NuclearRegulatoryCommissionRegionI475AllendaleRoadKingofPrussia,PA19406GinnaSeniorResidentInspector 0h AttachmentIRochesterGasandElectric(RG&E)requestsanexemptionto10CFR50.60basedonthecriteriaof10CFR50.12(a)(2)(iii)whichallowstheNuclearRegulatoryCommission(NRC)tograntanexemptionfromtherequirementsoftheregulationscontainedin10CFRPart50ifcompliancewiththeregulationresultsinunduehardshiporothercoststhataresignificantlyinexcessofthosecontemplatedwhentheregulationwasadopted.Specifically,theexemptionisbeingrequestedwithrespectto10CFR50.60whichrequiresthatalllightwaternuclearpowerreactorsmeetthefracturetoughnessandmaterialsurveillanceprogramrequirementsforthereactorcoolantpressureboundarycontainedin10CFRPart50,AppendicesGandH.AppendixGSectionIV.A.2.brequiresthatthepressure-temperature(P/T)limitsandminimumtemperaturerequirementsforthereactorvesselbeatleastasconservativeasthelimitsobtainedthroughuseofthemethodsofanalysisandmarginsofsafetyofAppendixGtoSectionXIoftheAmericanSocietyofMechanicalEngineers(ASME)Code.Inaddition,Table1ofAppendixGrequiresthat40'Fbeaddedtothisvaluetoobtainadditionalmargin.IncludedwithinAppendixGofASMESectionXI(seeparagraphG-2215)isthedeterminationofthelowtemperatureoverpressureprotection(LTOP)systemenabletemperature.TheLTOPsystemisusedbyplantstoautomaticallyprotectthereactorcoolantsystemboundaryfromServiceAorBlowtemperatureoverpressureevents(i.e.,normalandanticipatedoperationaloccurrences)duringreactorstartupandshutdownoperations.TheenabletemperatureisthetemperaturebelowwhichtheLTOPsystemmustbeinserviceinordertolimitthemaximumpressureinthereactorvesselto110%ofthepressurelimitnecessarytosatisfytheremainingrequirementsofAppendixGofASMESectionXI.AppendixGofASMESectionXIspecifiesthattheLTOPenabletemperaturemustbe200F,orthereactorcoolantsystem(RCS)temperaturecorrespondingtoareactorvesselmetaltemperatureofRT>>~"'50'F,whicheverisgreater.Therefore,10CFRPart50,AppendixGeffectivelyrequiresaLTOPenabletemperatureof240ForRT>>>+90'F,whicheverisgreater(with40'Fmarginincluded).BasedonFigures1and2containedwithinReference1,theLTOPenabletemperatureforGinnaStationwouldbe322'F(i.e.,RT>>~at1/4T+90F).However,thisdoesnotincludeinstrumentuncertainty.Thatis,theNRCrequiresthatinstrumentuncertaintybeincludedbeyondthe40'Fmarginaddedby10CFRPart50,AppendixGtoaddressthereactorcoolanttemperature"correspondingtoareactorvesselmetaltemperature"ofRT>>Y+50'FasspecifiedinAppendixGtoASMESectionXI.BasedonRG&Einstrumentuncertaintycalculations,theLTOPenabletemperatureforGinnaStationwouldbe356'F(i.e.,19FuncertaintyfromRCST,.widerangeindicationplusestimated15'F1/4TtoRCSfluidtemperatureuncertainty).Thisnewenabletemperaturevaluecreatesseveralproblemsasdescribedbelow.RT>>YisdefinedinRegulatoryGuide1.99,Revision2asthehighestadjustedreferencetemperature(forweldorbasemetalinthebeltlineregion)atadistanceofonefourthofthevesselsectionthickness(1/4T)fromthevesselwettedinnersurface.
TheGinnaStationImprovedTechnicalSpecifications(ITS)arewrittenaroundplantoperatingconditions(i.e.,modes)foreaseofuse.Amodechangeoccursatareactorcoolantsystemtemperatureof350F(i.e.,Mode4isbelow350'FwhileMode3isabove350'F).ThecurrentLTOPenabletemperature(seeLCO3.4.12)is328'FwhichisinMode4.Avalueof356'FwouldrequiretheLTOPsystemtoalsobeoperableinMode3andimpactLCOs3.3.2(ESFASInstrumentation),3.4.11(PressurizerPORVs),3.4.12(LTOPSystem),and3.5.2(ECCS-Modes1,2and3).Specifically,LCO3.4.12wouldhavetoberevisedtoincludepartofMode3initsModeofApplicabilityrequirements,whileLCOs3.3.2,3.4.11,and3.5.2wouldhavetoberevisedtoremovepartofMode3fromtheirModeofApplicability.RevisingtheModeofApplicabilityforLCOs3.3.2,3.4.11,and3.5.2hasseveralundesirableeffects.First,theITSbasesforLCO3.4.11statethatthepressurizerPORVsarerequiredtooperableformanualoperationinModes1,2,and3tomitigatetheconsequencesofasteamgeneratortuberupture(SGTR)eventandpreventchallengestothepressurizersafetyvalves.RequiringthePORVstobeintheirLTOPconfigurationwithaliftsetpointofM411psig(seeReference1)uptoaRCStemperatureof356'Fprovidesverylittleoperatingmarginduringstartupandshutdownconditions.WhilethenewenabletemperaturedoesnotpreventthecapabilityofthepressurizerPORVstomitigateaSGTReventorpreventchallengestothepressurizersafeties,itdoesincreasethepotentialofaninadvertentliftofthePORVs(i.e,,aPORVloss-of-coolant-accident(LOCA)).TheinadvertentPORVliftisduetothelimitedoperatingmarginavailableasRCSpressureandtemperaturecloselyfollowoneanotherundertheseconditions.Assuch,withtheadditionofinstrumentdrift,asetpointof~411psigcouldresultinaPORVliftbelow400psig(ornear356'F).Inaddition,therewouldbenomarginbetweenconfiguringthePORVsforLTOPconditionsandforpoweroperationconditionsascurrentlyexists(i.e.,withanenabletemperatureof328'F,thereisa22FwindowtoconfigurethePORVsforLTOPandpoweroperatio'n).Second,LCOs3.3.2and3.5.2requirethehighpressuresafetyinjection(SI)pumps(includingactuationsignalstothepumps)tobeoperableinModes1,2,and3.TheSIpumpsprovideprotectionwithrespecttopreventingareturntocriticalityfollowingamainsteamlinebreak,andRCSinventorycontrolandcorecoolingfollowingaLOCAandSGTRevent.LCO3.4.12requiresthattheSIpumpsbeincapableofinjectingintotheRCSwheneverthePORVsareprovidingLTOPprotection(whichtheywouldbewithRCS)350F).ThebasesforSRs3.4.12.1,3.12.1.2,3.4.12.3defineincapableofinjectingas:a.placingthepumpcontrolswitchinthepull-stoppositionandclosingatleastonevalveinthedischargeflowpath;b.lockingclosedamanualisolationvalveintheinjectionpath;orc.closingamotoroperatedisolationvalveintheinjectionpathandremovingtheACpowersource.
l Whilethereisnospecificanalysisofamainsteamlinebreak,LOCA,orSGTRataRCStemperatureof356'Fsincethisisanon-limitingcondition(versushotzeropowerorfullpower),theaccidentanalysisassumesthatSIisavailableveryrapidly(e.g.,within5secondsofgeneratingaSIsignal).ImplementinganyoneoftheabovethreemeansforrenderingaSIpumpincapableofinjectionintotheRCSwouldobviouslytakeseveralminutesorevenlongertoprovideSIinjectioncapability.Consequently,theadditionaltimepriortotheavailabilityofSIwouldhavetobeconfirmedwithintheaccidentanalysisasbeingacceptable,SinceRG&EdoesnothaveLOCAanalysiscapabilities,avendorwithanapprovedmethodologywouldhavetobeusedatanexpectedminimumcostof$100,000forthisLOCAevaluation.Furthermore,NRCreviewandapprovalofthisanalysiswouldbecostlyandtime-consuming.Insummary,requiringtheLTOPenabletemperaturetobe240'ForRT>>~+90F,whicheverisgreater,withanadditionalrequirementtoaddrelevantinstrumentuncertaintiesresultsinatemperatureforGinnaStationthat:(1)significantlyincreasesthepotentialforaPORVLOCAduringstartupandshutdownactivities,(2)requiresplacingthehighpressureSIpumpsincapableofinjectingintotheRCSduringmodesofoperationwhentheSIpumpsarecurrentlyrequiredtobeavailableforautomaticinjection(i.e.,adegradationininstalledsafetycapability),and(3)wouldrequireRG&Etore-performtheaccidentanalysisforLOCAs,SGTRs,andmainsteamlinebreaksatsignificantcost.Therefore,per10CFR50.12(a)(2)(iii),RG&Erequestsanexemptionfromtherequirementsoftheregulationscontainedin10CFR50.60withrespecttotheLTOPenabletemperatureasaresultofunduehardship.Initsplace,RG&ErequeststouseASMESectionXI,CodeCaseN-514,"LowTemperatureOverpressureProtectionSectionXI,.Division1"(AttachmentII)toremovetheadditional40'Fconserativism.TherearemanyconservatismsincorporatedintheP/TlimitscalculatedusingthecurrentmethodologyofASMECodeSectionXI,AppendixG,ASMEexplicitlyrecognizedtheamountofmargininherentintheAppendixGP/TlimitsbyapprovingCodeCaseN-514onFebruary12,1992andincorporatingitintothe1993AddendatoASMECodeSectionXI,AppendixG.CodeCaseN-514effectivelyremovesthe40'Fmarginaddedby10CFRPart50,AppendixGsuchthattheLTOPenabletemperaturewouldbe200'ForRT>>~+50'F,whicheverisgreaterwithrelevantinstrumentuncertaintiesadded.Usingthesamevaluesasabove,thiswouldresultinaLTOPenabletemperatureof316'FforGinnaStationwhichiswithinthesameoperatingmodeastheexistingenabletemperature.FollowingtheuseofASMECodeCaseN-514,theLTOPsystemwillstillfunctiontomeetthefracturetoughnessrequirementsofthepressure-retainingcomponentsofthereactorcoolantpressureboundaryandprovideadequatemarginofsafetyduringaconditionofnormaloperation,includinganticipatedoperationaloccurrences,towhichthepressureboundarymaybesubjectedoveritslifetime.Assuch,useofCodeCaseN-514willstillmeettheunderlyingpurposeof10CFR50,60.Thiscodecasehasbeengrantedforotherlicensees(Reference2)~
~~ References2.LetterfromR.C.Mecredy,RG&E,toG.S.Vissing,NRC,ReactorCoolantSystem(RCS)PressureandTemperatureLimitsReport(PTLR),datedDecember30,1996.LetterfromC.Y.Shiraki,NRC,toD.L.Farrar,CommonwealthEdisonCompany,ExemptionfromRequirementsof10CFR50.60,AcceptanceCriteriaforFracturePreventionforLightwaterNuclearPowerReactorsforNormalOperation-ZionNuclearPowerStation,Units1and2(TACNosM95119andM95120),datedJuly30,1996.3.LetterfromG.F.Dick,NRC,toLM.Johnson,CommonwealthEdisonCo.,ExemptionfromRequirementsof10CFR50,60UsingSafetyMarginsRecommendedinASMEBoiler&PressureVesselCodeCaseN-514-ByronStationUnits1and2,datedNovember29,1996.4.LetterfromD.B,Matthews,toJ.PO'Hanlon,VirginiaElectric&PowerCo.,Exemptionto10CFR50.60PermittingUseofSafetyMarginsRecommendedinASMECodeCaseN-514,"LowTemperatureOverpressureProtection,"inLieuofSafetyMarginsRequiredbyAppendixGto10CFR50-SurryPowerStationUnits1and2,datedOctober31,1995.LetterfromH.N.Berkow,NRC,toC.K.McCoy,GeorgiaPowerCo.,ExemptionPomRequirementsoflOCFR50.60,"AcceptanceCriteriaforFracturePreventionforLight-WaterNuclearPowerReactorsforNormalOperation,"UsingSafetyMarginsRecommendedinASMECodeCaseN-514-VogtleNuclearPlant,Units1and2,datedJune5,1995.6.LetterfromJ.N.Hannon,NRC,toK.M.Hass,ConsumersPowerCo.,ExemptionPomRequirementsof10CFR50.60,"AcceptanceCriteriaforFracturePreventionforLWRNuclearPowerReactorsforNormalOperation,"UsingSafetyMarginsRecommendedinASMECodeCaseN-514-PalisadesNuclearPlant,datedMarch3,1995.
Attachnent2CASEN-5l4CASESOFASMEBOILERANDPRESSUREVESSELCODEApprovalDate:February12,1992SeeNumericalIndexforexpirationendenyreaffirmationdotes.CaseN-514LowTemperatureOverprcssureProtectionSectionXI,DivisionlInquiry:SectionXI,Division1,IWB-3730,re-quiresthatduringreactoroperation,loadandtem-peratureconditionsbemaintainedtoprovidepro-tectionagainstfailureduetothepresenceofpostulatedflawsintheferriticportionsofthereactorcoolantpressureboundary.Forthoseplantshavinglowtemperatureoverpressureprotection(LTOP)systems,whatloadandtemperatureconditionsunderIWB-3730m'aybeusedtoprovideprotectionagainstfailureduringreactorstart-upandshutdownopera-tionduetolowtemperatureoverpressureeventsthathavebeenclassifiedasServiceLevelAorBeventsfReply:ItistheopinionoftheCommitteethatforthoseplantshavingLTOPsystemsthefollowingloadandtemperatureconditionsmaybeusedtoprovideprotectionagainstfailureduringreactorstart-upandshutdownoperationduetolowtemperatureover-pressureeventsthathavebeenclassifiedasServiceLevelAorBevents.LTOPsystemsshallbeeffectiveatcoolanttemperatureslessthan200'Foratcoolanttemperatures'orrespondingtoareactorvesselmetaltemperature'essthanRT>>+50'F,which-everisgreater.LTOPsystemsshalllimit.themaxi-mumpressureinthevesselto110%ofthepressuredeterminedtosatisfyAppendixG,para.6-2215ofSectionXI,Division1.'hecoolanttemperatureisthereactorcoolantinlettempera-ture.'hevesselmetaltcmpcratureisthctempcraturcatadistanceonc.fourthofthcvcssclsectionthicknessfromtheinsidesurfaceinthevesselbcltlineregion.RT,isthehighestadjustedrcfc-rcncetcmpcraturcforweldorbasemetalinthcbcltlincregionatadistanceonc-fourthofthcvcssclsectionthicknessfromthcvcssclinsidesurface,asdetcrrnincdbyRegulatoryGuide1.99,Rcv.2.893SUPP.4-NC 0,4<ppre