ML13056A601

San Onofre, Unit 2 - Response to Request for Additional Information (RAI 32) Regarding Confirmatory Action Letter Response

ML13056A601
Person / Time
Site:	San Onofre
Issue date:	02/25/2013
From:	St.Onge R J Southern California Edison Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC ME9727
Download: ML13056A601 (9)

Text

SOUTHERNCALIFORNIAEDISONRichardJ.St.OngeDirector,NuclearRegulatoryAffairsandEmergencyPlanningAnEDISONINTERNATIONALCompanyFebruary25,2013U.S.NuclearRegulatoryCommissionATTN:DocumentControlDeskWashington,DC

Subject:

DocketNo.50-361ResponsetoRequestforAdditionalInformation(RAI32)RegardingConfirmatoryActionLetterResponse(TACNo.ME9727)SanOnofreNuclearGeneratingStation,Unit210CFR50.4

References:

1.LetterfromMr.ElmoE.Collins(USNRC)toMr.PeterT.Dietrich(SCE),datedMarch27,2012,ConfirmatoryActionLetter4-12-001,SanOnofreNuclearGeneratingStation,Units2and3,CommitmentstoAddressSteamGeneratorTubeDegradation2.LetterfromMr.Peter1.Dietrich(SCE)toMr.ElmoE.Collins(USNRC),datedOctober3,2012,ConfirmatoryActionLetter-ActionstoAddressSteamGeneratorTubeDeqradation,SanOnofreNuclearGeneratingStation,Unit2,3.LetterfromMr.JamesR.Hall(USNRC)toMr.Peter1.Dietrich(SCE),datedDecember26,2012,RequestforAdditionalInformationRegardingResponsetoConfirmatoryActionLetter,SanOnofreNuclearGeneratingStation,Unit2

DearSirorMadam,

OnMarch27,2012,theNuclearRegulatoryCommission(NRC)issuedaConfirmatoryActionLetter(CAL)(Reference1)toSouthernCaliforniaEdison(SCE)describingactionsthattheNRCandSCEagreedwouldbecompletedtoaddressissuesidentifiedinthesteamgeneratortubesofSanOnofreNuclearGeneratingStation(SONGS)Units2and3.InalettertotheNRCdatedOctober3,2012(Reference2),SCEreportedcompletionoftheUnit2CALactionsandincludedaReturntoServiceReport(RTSR)thatprovideddetailsoftheircompletion.ByletterdatedDecember26,2012(Reference3),theNRCissuedRequestsforAdditional.Information(RAls)regardingtheCALresponse.Enclosure2ofthisletterprovidestheresponsetoRAI32,whichrelatestocompliancewithTechnicalSpecification(TS)5.5.2.11.P.O.Box128SanClemente,CA92672 DocumentControlDesk February25,2013Enclosure1providesanewcommitmentidentifiedinthisletter.Ifyouhaveanyquestionsorrequireadditionalinformation,pleasecallmeat(949)368-6240.Sincerely,

Enclosures:

1.Commitments2.ResponsetoRAI32cc:E.E.Collins,RegionalAdministrator,NRCRegionIVJ.R.Hall,NRCProjectManager,SONGSUnits2and3G.G.Warnick,NRCSeniorResidentInspector,SONGSUnits2and3R.E.Lantz,BranchChief,DivisionofReactorProjects,NRCRegionIV ENCLOSURE1CommitmentsPage1of7 Enclosure1CommitmentsThistableidentifiestheactiondiscussedinthisletterthatSouthernCaliforniaEdison(SeE)commitstoperform.AnyotheractionsdiscussedinthissubmittalaredescribedfortheNRC'sinformationandarenotcommitments.DescriptionofCommitmentsScheduledCompletionDate1SCEwillprovideanOAthatincludesanevaluationofsteamMarch15,2013generatorTTWforoperationuptotheRTP.ThisOAwillbeprovidedtotheNRCforreviewbyMarch15,2013.InthisOA,SCEwillsupplementtheIntertekOA(Enclosure2,Attachment6,AppendixCoftheCALResponseLetter)whichisbasedon'traditional'industryguidelines.TheOAsupplementwilldemonstratethattheStructuralIntegrityPerformanceCriteria(SIPC)andtheAccidentInducedLeakagePerformanceCriteria(AILPC)aresatisfiedfor100%RatedThermalPower(RTP).Page2of7 ENCLOSURE2SOUTHERNCALIFORNIAEDISONRESPONSETOREQUESTFORADDITIONALINFORMATIONREGARDINGRESPONSETOCONFIRMATORYACTIONLETTERDOCKETNO.50-361TACNO.ME9727ResponsetoRAI32Page3of7 RAI32SONGSUnit2TechnicalSpecification(TS)3.4.17requiresthatsteamgeneratorstructuralintegritybemaintainedinModes1,2,3,and4(PowerOperation,Startup,HotStandby,andHotShutdown,respectively).LimitingConditionforOperation(LCO)3.4.17,"SteamGenerator(SG)TubeIntegrity,"requiresthatsteamgeneratortubeintegrityshallbemaintainedandallsteamgeneratortubessatisfyingthetuberepaircriteriashallbepluggedinaccordancewiththeSteamGeneratorPrograminMODES1,2,3,and4.Thesteamgeneratortuberupture(SGTR)accidentisthelimitingdesignbasiseventforSGtubesandavoidinganSGTRisthebasisforLCO3.4.17.SurveillanceRequirement(SR)3.4.17.1requires"VerifySGtubeintegrityinaccordancewiththeSteamGeneratorProgram."ThestructuralintegrityperformancecriterionisdescribedinSONGSUnit2TS5.5.2.11.b.1asfollows:Allin-servicesteamgeneratortubesshallretainstructuralintegrityoverthefullrangeofnormaloperatingconditions(includingstartup,operationinthepowerrange,hotstandby,cooldownandallanticipatedtransientsincludedinthedesignspecification)anddesignbasisaccidents.Thisincludesretainingasafetyfactorof3.0againstburstundernormalsteadystatefullpoweroperationprimary-to-secondarypressuredifferentialandasafetyfactorof1.4againstburstappliedtothedesignbasisaccidentprimary-to-secondarypressuredifferentials.Apartfromtheaboverequirements,additionalloadingconditionsassociatedwiththedesignbasisaccidents,orcombinationofaccidentsinaccordancewiththedesignandlicensingbasis,shallalsobeevaluatedtodetermineiftheassociatedloadscontributesignificantlytoburstorcollapse.Intheassessmentoftubeintegrity,thoseloadsthatdosignificantlyaffectburstorcollapseshallbedeterminedandassessedincombinationwiththeloadsduetopressurewithasafetyfactorof1.2onthecombinedprimaryloadsand1.0onaxialsecondaryloads.[emphasisadded]AsdescribedintheSONGSUnit2license,SCE"isauthorizedtooperatethefacilityatreactorcorepowerlevelsnotinexcessoffullpower(3438megawattsthermal),"whichisalsodefinedasRatedThermalPower(RTP).InSCE'soperationalassessment(OA)thatevaluatedtubedegradationcausedbymechanismsotherthantube-to-tubewear(Reference3),onPage30of32,SCEconcludedthat"thereisreasonableassurancethattheperformancecriteriaforthenon-[tube-to-tubewear]TTWdegradationwillbemetifUnit2weretooperateforafullfuelcycleof1.577EFPY[effectivefullpoweryears]at100%reactorpower."ThusitappearsthatinRAIReference3,SCEconsideredtherequirementsofTS5.5.2.11.b.1byaddressingthelicensedfullpowercondition.Incontrast,SCEperformedthreeotheroperationalassessmentsthatevaluatedtubedegradationduetotube-to-tubewear(References4-6),butitappearsthatintheseOAs,SCEaddressedstructuralintegrityrequirementsforTTWonlyat70%reactorpower,insteadofat100%reactorpower.Forexample,inReference4,Section10.0,"Conclusions,"page117of129,SCEstates:"A70%operatingpowerlevelreturnstheUnit2steamgeneratorstowithintheoperationalenvelopeofdemonstratedsuccessfuloperation...Operationat70%powerassuresin-planestability(SR<1)withoutdependenceonanyeffectivein-planesupportsforU-bends."Page4of7 Therefore,itappearsthatSCEhasnotprovidedanoperationalassessmentthataddressescompliancewithTS5.5.2.11.bfortube-to-tubewear,withoutrelianceoncompensatorymeasures(e.g.,limitingreactorpowerto70%RTP).PleaseclarifyhowtheinformationsubmittedbySCEdemonstratesthatthestructuralintegrityperformancecriterioninTS5.5.2.11.b.1ismetforoperationwithincurrentlicensedlimitsuptothelicensedRTP,orprovideanoperationalassessmentthatincludesanevaluationofsteamgeneratorTTWforoperationuptotheRTP.RESPONSEThisRAIresponseistoclarifytheinformationpreviouslysubmittedintheOctober3,2012ConfirmatoryActionLetter(CAL)responseandtoexplaincompliancewithTechnicalSpecification(TS)5.5.2.11.b.1overthefullrangeofnormaloperatingconditionsuptoandincluding"normalsteady-statefullpoweroperation."TheRAIusesthetermRatedThermalPower(RTP)inreferringtocompliancewithTS5.5.2.11;however,thisTSprovisiondoesnotusethatterm.Asdetailedbelow,SCE'spositionisthatcompliancewithTS5.5.2.11requiresdemonstrationthatthestructuralintegrityperformancecriterionmustbemetuptoandincludingthenormaloperatingconditionsinthecurrentlicensingbasis,whichinthiscaseisdistinctfromRatedThermalPower.Inaddition,asrequestedbytheRAI,SCEwillprovideanOperationalAssessmentofTTWforoperationuptotheRTP(100%power).Inthisresponse,SCEisalsoprovidingadescriptionoftheactionsitintendstotakefollowingreturntoserviceofUnit2forCycle17relevanttotheissuesinthisRAI.CompliancewithTechnicalSpecificationRequirementsLimitingConditionforOperation(LCO)3.4.17requiresthatsteamgenerator(SG)tubeintegritybemaintained.ThebasesforTS3.4.17statethat:SGtubeintegritymeansthatthetubesarecapableofperformingtheirintendedRCPBsafetyfunctionconsistentwiththelicensingbasis,includingapplicableregulatoryrequirements.TheBasesforTS3.4.17alsostatethattheSCESGProgramisthemeansbywhichSGtubeintegrityismaintainedandthattheSGProgramisbasedonNEI97-06,"SteamGeneratorProgramGuidelines."TS5.5.2.11specifiesthattheSGprogramisestablishedandimplementedtoensurethatSGtubeintegrityismaintained.InadditiontheSGProgramincludesprovisionsforconditionmonitoring,performancecriteriafortubeintegrity,tuberepair,tubeinspections,andmonitoringoperationalprimarytosecondaryleakage.TheprovisionsforSGtubeintegrityarecontainedinTS5.5.2.11.b.1.Thedefinitionoftubeintegrityincludesstructuralintegrity,whichmustbemaintainedoverthefullrangeofnormaloperatingconditions.Asafetyfactorof3.0mustbemaintainedagainstburstundernormalsteadystatefullpoweroperationprimarytosecondarypressuredifferentialandasafetyfactorof1.4againstburstappliedtodesignbasisaccidentprimarytosecondarypressuredifferentials.AccidentinducedleakageandoperationalleakagearealsoassessedaspartofTS5.5.2.11.b.1.Page5of7 TS5.5.2.11doesnotrefertoRatedThermalPowerastheupperboundonthe"fullrangeofnormaloperatingconditions."Itrefersonlyto"normalsteadystatefullpoweroperation."TheabsenceofthetermRatedThermalPowerinTS5.5.2.11issignificant,giventhatthereareanumberofotherprovisionsintheTSsthatusethetermRatedThermalPower,includingTSTable1.1-1,SurveillanceRequirement3.1.4.2,Figure3.4.16-1,andSection5.7.1.5.c.Instead,TS5.5.2.11refersto"normalsteadystatefullpoweroperation."TheclearpurposeofTS5.5.2.11istoensurethattheSGtubeswillretaintheirintegrityovertherangeofoperatingconditionstowhichtheywillbesubjected.Inthiscase,thatrangeislimitedto70%power.Therefore,SCE'sGAs,whichdemonstratethattubeintegritywillbemaintaineduptothatlevel,meettheliteralwordsandpurposeofthisTSprovision.Inaddition,"normalsteadystatefullpoweroperation"isthemaximumpowerlevelinaccordancewiththecurrentlicensingbasis,whichbasedonthecommitmentmadeinresponsetotheCALis70%powerfortheproposedoperatingperiod.The70%powercommitmentisanadministrativerestrictionproposedbySCEbasedontheoperatingassessmentsfortheoperatingperiod.Oncemade,thiscommitmentbecomespartoftheSCEUnit2CurrentLicensingBasis.TheNRCdefinesCurrentLicensingBasis(CLB)in10CFR54.3asfollows:Currentlicensingbasis(CLB)isthesetofNRCrequirementsapplicabletoaspecificplantandalicensee'swrittencommitmentsforensuringcompliancewithandoperationwithinapplicableNRCrequirementsandtheplant-specificdesignbasis(includingallmodificationsandadditionstosuchcommitmentsoverthelifeofthelicense)thataredocketedandineffect.AsaresultofSCE'sformalcommitmentestablishedintheCALresponseandUnit2ReturntoServiceReport,the."normalsteadystatefullpower"intheCurrentLicensingBasisforUnit2is70%powerfortheproposedoperatingperiod.SincealloftheOperationalAssessments(OAs)wereperformedforoperationatorabove70%power,TS5.5.2.11complianceisdemonstrated.OperationalAssessmentat100%RatedThermalPower(RTP)OperationalAssessments(OAs)areperformedinaccordancewiththeSCESGProgramtoensureSGtubeintegrityandleakageintegritywillbemaintainedduringtheoperatingperiodpriortothenextplannedSGinspection.SCEprovidedanumberofOAsforrestartofUnit2.TheOAthataddressestubewearmechanismsotherthantube-to-tubewear(TTW)wasperformedat100%power.ThreeadditionalOAswereperformedindependentlyusingdiversemethodstoaddressTTW.ThethreeOAsaddressingTTWwereperformedusingthethermal-hydraulicconditionsat70%power.AsrequestedintheRAI,SCEwillprovideanOAthatincludesanevaluationofsteamgeneratorTTWforoperationuptotheRTP.ThisOAwillbeprovidedtotheNRCforreviewbyMarch15,2013.InthisOA,SCEwillsupplementtheIntertekOA(Enclosure2,Attachment6,AppendixCoftheCALResponseLetter)whichisbasedon'traditional'industryguidelines.TheOAsupplementwilldemonstratethattheStructuralIntegrityPerformanceCriteria(SIPC)andtheAccidentInducedLeakagePerformanceCriteria(AILPC)aresatisfiedfor100%RatedThermalPower(RTP).[NewCommitment]Page6of7 TheremainingTTWOAswillcontinuetobeusedinourdecisiontorestrictoperationto70%power.TheseOAsdemonstratethatsufficientmargintotheonsetoffluidelasticinstabilityexistsat70%power.ActionstobetakenfollowingreturntoserviceforUnit2SCE'sCALresponseprovidedseveralinterimactionsregardingoperationfortheinitial150dayperiodfollowingstartupfromthecurrentoutage.Followingthatinitial150dayperiod,SCEintendstotakethefollowingactionsonaninterimbasisuntilalong-termpowerlevelforUnit2isestablished:1.Operationwillbelimitedto70%powerunlessapprovalforahigherpowerlevelisobtainedfromtheNRC.IfSCErepairstheexistingsteamgeneratorsforUnit2,orifadditionaltubeinspectionsoranalysesprovidenewinformationdemonstratingthatUnit2isnotsusceptibletoTTWbyin-planeFEIatahigherpowerlevel,SCEmayprovidetheNRCwithjustification(s)foroperatingathigherpowerlevelsupto100%power.SCEwillnotoperateUnit2atpowerlevelshigherthan70%untiltheNRChasauthorizedoperationathigherpowerlevels.2.Followingrestartfromthecurrentoutage,operationofSONGSUnit2willberestrictedto150cumulativedaysofoperationatorabove15%ofRTPof3438MWt.After150daysofcumulativeoperationatorabove15%power,SCEwillshutdownUnit2foracyclesteamgeneratortubeinspectionoutageandwillperformtubeinspectionsinaccordancewithTechnicalSpecification5.5.2.11andSection8.3oftheUnit2ReturntoService(RTS)Report.Steamgeneratortubeinspectionsperformedduringsubsequentinspectionoutageswillbeperformedusingthesameinspectionscopeandmethods.3.Usingtheresultsofthetubeinspectionduringthefirstmid-cycleoutageduringCycle17,SCEwillprepareanupdatedOAforUnit2.TheOAwillbeperformedforoperationat70%ofRTPandwilldeterminethedurationofthesubsequentoperatingperioduntilthenextinspectionoutage.Followinganysubsequentoutagewithsteamgeneratortubeinspections,SCEwillupdatethisOAasneededtosupportoperationattheintendedpowerlevel.4.Ateachinspection,SGtubewearindicationswillbeevaluatedinaccordancewiththeConditionMonitoringrequirementsoftheSONGSTechnicalSpecificationsandindustryguidelinesforstructuralandleakageintegrity.ConfirmednewTTWindicationslegacy)orconfirmedincreasesinsizeofexisting(previouslyidentified)TTWindicationswillbeassessedtodetermineiftheyaretheresultofin-planeFE!.SCEwillrestartUnit2whentheinspectionprogramdemonstratesreasonableassurancethatTTWcausedbyin-planeFEIdidnotoccurandconditionmonitoringdemonstratestubeintegrityperformancecriteriaaresatisfied.SCEwilloperateuptothesamepowerlevelallowedforthepreviousoperatingperiodandfortheintervalspecifiedintheupdatedOA.ThisupdatetotheOAwillbepreparedwithin90daysafterMode4entryasrequiredbyindustryguidelines.Ifin-planeFEIisobserved,SCEwillnotrestartUnit2withoutspecificdiscussionswiththeNRC.SCEintendstousetheaboveapproachuntilitdeterminesthelong-termoperationallimitsfortheUnit2SG's.SCEwillinformtheNRCwhenthedeterminationismadeofwhetherUnit2canbereturnedto100%poweroperationorlong-termoperationatreducedpowerisneeded.Page7of7