ML13056A601

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

SOUTHERN CALIFORNIA EDISONRichard J.St.Onge Director, Nucle ar Regulatory Affair s and Emergency Pl anning An EDISON INTERNATIONAL Company February 25, 2013 U.S.Nuclear Regulatory Commission ATTN: DocumentControlDesk Washington

, DC

Subject:

DocketNo.50-361 Response to Request for Additional Information(RAI32)Regarding Confirmatory Action Letter Response(TACNo.ME9727)

San Onofre Nuclear Generating Station,Unit210CFR50.4

References:

1.LetterfromMr.ElmoE

.Collins(USNRC)toMr.PeterT

.Dietrich(SCE),datedMarch27,2012, ConfirmatoryActionLetter4-12-001,SanOnofre Nuclear Generating Station ,Units2and3, Commitments to Address Steam Generator Tube Degradation2.LetterfromMr.Peter 1.Dietrich(SCE)toMr.Elmo E.Collins(USNRC),dated October3,2012, ConfirmatoryActionLetter-Actionsto Address Steam Generator Tube Deqradation, San Onofre Nuclear GeneratingStation,Unit2

,3.Letter from Mr.JamesR.Hall(USNRC)toMr.Peter 1.Dietrich(SCE)

, dated December 26,2012,Requestfor Additional Information Regarding Response to ConfirmatoryActionLetter,San Onofre Nuclear GeneratingStation,Unit2

DearSirorMadam,

OnMarch 27,2012 , the Nuclear Regulatory Commission(NRC)issueda Confirmatory ActionLetter(CAL)(Reference1)toSouthern CaliforniaEdison(SCE) describingactionsthattheNRCandSCEagreedwouldbe completedtoaddressissuesidentifiedinthesteam generator tubesofSanOnofre Nuclear Generating Station (SONGS)Units2and3.InalettertotheNRCdated October3,2012 (Reference2),SCEreported completionoftheUnit2CALactionsandincludedaReturntoServiceReport(RTSR)thatprovideddetailsof their completion.Byletterdated December26,2012 (Reference3),theNRCissuedRequestsfor Additional

.Information (RAls)regardingtheCALresponse

.Enclosure2ofthisletterprovidestheresponsetoRAI32,whichrelatesto compliance with Technical Specification(TS)5.5.2.11.P.O.Bo x 128SanCl emente , CA 92672 Document Control Desk-2-February 25, 2013 Enclosure 1 providesanew commitment identifiedinthisletter.Ifyouhaveany questions or require additional information, pleasecallmeat(949) 368-6240.Sincerely ,

Enclosures:

1.Commitments 2.ResponsetoRAI32cc:E.E.Collins, Regional Administrator, NRC Region IV J.R.Hall , NRC Project Manager, SONGS Units2and3G.G.Warnick , NRC Senior Resident Inspector, SONGSUnits2and3 R.E.Lantz, Branch Chief, Division of Reactor Projects, NRC Region IV ENCLOSURE 1 CommitmentsPage1of7 CommitmentsThistable identifiestheaction discussedinthis letterthatSouthern California Edison (SeE)commitstoperform

.Anyotheractions discussedinthissubmittalare describedfortheNRC's informationandarenot commitments.

Description of Commitments Scheduled Completion Date 1SCEwill provideanOAthat includes an evaluationofsteamMarch15,2013 generator TTWforoperationuptotheRTP.ThisOAwillbeprovidedtotheNRCforreviewbyMarch15

,2013.InthisOA,SCEwill supplement the Intertek OA (Enclosure 2, Attachment 6 , Appendix CoftheCAL ResponseLetter)whichisbasedon

'traditional' industry guidelines.TheOA supplement will demonstratethatthe Structural Integrity PerformanceCriteria(SIPC)andthe Accident Induced Leakage PerformanceCriteria(AILPC)aresatisfiedfor100%Rated Thermal Power (RTP).Page2of7 ENCLOSURE 2 SOUTHERN CALIFORNIA EDISON RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDINGRESPONSETO CONFIRMATORY ACTION LETTERDOCKETNO.50-361TACNO.ME9727ResponsetoRAI32Page3of7 RAI32SONGSUnit2TechnicalSpecification(TS)3.4

.17requiresthatsteam generator structural integr ity be maintainedinModes1 ,2,3,and4(PowerOperation

,Startup,HotStandby,andHot Shutdown, respectively).LimitingConditionfo rOperation(LCO)3.4

.17,"Steam Generator (SG)TubeIntegrity,"requiresthatsteam generator tube integrityshallbe maintainedandallsteam generatortubessatisfyingthetuberepaircriteriashallbepluggedin accordancewiththeSteam GeneratorPrograminMODES1,2

,3,and4.Thesteam generatortuberupture (SGTR)accidentisthelimitingdesignbasiseventforSGtubesandavoidinganSGTRisthebas is forLCO3.4.17.Surveillance Requirement(SR)3.4.17.1requires"VerifySGtube integrity in accordancewiththeSteam Generator Program." The structural integrity performancecriterionisdescribedinSONGSUnit2TS5.5.2.11.b.1as follows: All in-service steam generatortubesshallretainstructural integrityoverthefullrangeofnormaloperatingconditions(includingstartup, operationinthepowerrange,hotstandby,cooldownandall anticipatedtransientsincludedinthedesign specification)anddesignbasisaccidents.Thisincludesretaininga safety factorof3.0againstburstundernormalsteadystatefullpower operation primary-to-secondarypressuredifferentialandasafety factorof1.4 againstburstappliedtothedesignbasis accident primary-to-secondary pressure differentials.Apartfromtheaboverequirements,additionalloading conditions associatedwiththedesignbasisaccidents,or combination of accidents in accordancewiththedesignandlicensingbasis,shallalsobeevaluatedtodetermineiftheassociatedloads contribute significantlytoburstorcollapse.Inthe assessmentoftubeintegrity,thoseloadsthatdo significantlyaffectburstorcollapseshallbe determinedandassessedin combinationwiththeloadsduetopressurewithasafety factorof1.2onthe combined primaryloadsand1.0onaxial secondary loads.[emphasis added]As describedintheSONGSUnit2license,SCE"isauthorizedto operatethefacilityatreactorcorepowerlevelsnotinexcessoffullpower(3438 megawatts thermal),"whichisalsodefinedasRated ThermalPower(RTP)

.InSCE's operational assessment(OA)thatevaluatedtube degradationcausedby mechanismsotherthan tube-to-tube wear (Reference3),onPage30of32

,SCEconcludedthat"thereis reasonable assurancethatthe performancecriteriaforthe non-[tube-to-tubewear]TTW degradationwillbemetifUnit2weretooperateforafullfuelcycleof1.577EFPY[effectivefullpoweryears]at100%

reactorpower."ThusitappearsthatinRAI Reference3,SCEconsideredthe requirementsofTS5.5.2.11.b.1by addressingthelicensedfullpowercondition.Incontrast,SCEperformedthreeother operational assessments that evaluated tube degradationdueto tube-to-tube wear (References 4-6),butitappearsthatintheseOAs,SCE addressed structural integrity requirementsforTTWonlyat70%

reactorpower,insteadofat 100%reactorpower.Forexample,inReference4,Section10.0,"Conclusions,"page117of129,SCEstates

"A70%operatingpowerlevelreturnstheUnit2steam generatorstowithinthe operational envelope of demonstrated successfuloperation...Operationat70%powerassures in-plane stability (SR<1)without dependenceonanyeffectivein-plane supportsforU-bends."Page4of7 Therefore ,itappearsthatSCEhasnotprovidedanoperational assessment that addresses compliancewithTS 5.5.2.11.b for tube-to-tube wear, withoutrelianceon compensatory measures (e.g., limiting reactorpowerto70%RTP).Pleaseclarifyhowthe informationsubmittedbySCE demonstratesthatthestructural integrity performancecriterioninTS5.5.2.11.b.1ismetforoperationwithincurrentlicensedlimitsuptothelicensedRTP,orprovidean operational assessmentthatincludesanevaluationofsteam generatorTTWforoperationuptotheRTP.

RESPONSEThisRAIresponseistoclarifytheinformationpreviouslysubmittedinthe October 3,2012 ConfirmatoryActionLetter(CAL)responseandtoexplain compliance with Technical Specification(TS)5.5.2.11.b.1overthefullrangeofnormaloperatingconditionsuptoandincluding"normal steady-statefullpoweroperation.

"TheRAIusesthetermRated ThermalPower(RTP)inreferringto compliancewithTS5.5.2.11;however,thisTSprovisiondoesnot usethatterm.Asdetailedbelow,SCE'spositionisthat compliancewithTS5.5.2

.11 requires demonstrationthatthestructural integrity performancecriterionmustbemetuptoandincludingthenormaloperatingconditionsinthecurrentlicensingbasis,whichinthiscaseis distinct from Rated Thermal Power.Inaddition,asrequestedbytheRAI,SCEwillprovideanOperational AssessmentofTTWfor operationuptotheRTP(100%power).Inthisresponse,SCEisalsoprovidingadescriptionoftheactionsitintendstotakefollowingreturntoserviceofUnit2forCycle17relevanttotheissuesinthisRAI.

Compliance with Technical Specification RequirementsLimitingConditionforOperation(LCO)3.4.17requiresthatsteam generator(SG)tube integritybemaintained.ThebasesforTS3.4.17statethat:SGtube integritymeansthatthetubesarecapableofperformingtheirintendedRCPBsafetyfunct ion consistentwiththelicensingbasis, including applicable regulatory requirements.TheBasesforTS3.4.17alsostatethattheSCESGProgramisthemeansbywhichSGtube integrityismaintainedandthattheSGProgramisbasedonNEI97-06,"Steam GeneratorProgramGuidelines.

"TS5.5.2.11specifiesthattheSGprogramis established and implementedtoensurethatSGtube integrityismaintained.InadditiontheSGProgram includes provisionsforconditionmonitoring, performancecriteriafortubeintegrity,tuberepair, tube inspections

,andmonitoring operationalprimaryto secondary leakage.The provisionsforSGtube integrityarecontainedinTS5.5.2.11.b.1.The definitionoftube integrityincludesstructuralintegrity,whichmustbemaintainedoverthefullrangeofnormaloperatingconditions.Asafety factorof3.0mustbemaintained against burst under normalsteadystatefullpoweroperation primary to secondary pressure differentialandasafety factorof1.4 againstburstappliedtodesignbasisaccident primary to secondary pressure differentials.

AccidentinducedleakageandoperationalleakagearealsoassessedaspartofTS5.5.2.11.b.1.Page5of7 TS5.5.2.11doesnotrefertoRatedThermalPowerasthe upperboundonthe "fullrangeofnormaloperatingconditions.

"Itrefersonlyto "normalsteadystatefullpoweroperation." The absenceofthetermRated ThermalPowerinTS5.5.2.11 is significant

,giventhattherearea number of other provisionsintheTSsthatusethetermRatedThermalPower,includingTSTable1.1-1, Surveillance Requirement 3.1.4.2 ,Figure3.4.16-1

,andSection5.7.1.5.c.Instead,TS5.5.2.11refersto"normalsteadystatefullpoweroperation.

"TheclearpurposeofTS5.5.2.11istoensurethattheSGtubeswillretaintheir integrityovertherangeofoperating conditionstowhichtheywillbesubjected.Inthiscase,thatrangeislimitedto70%power.

Therefore ,SCE'sGAs,which demonstratethattube integritywillbe maintaineduptothatlevel,meettheliteralwordsandpurposeofthisTSprovision

.Inaddition,"normal steadystatefullpoweroperation "isthemaximumpowerlevelin accordancewiththe currentlicensingbasis,whichbasedonthe commitmentmadeinresponsetotheCALis70%powerfortheproposedoperatingperiod

.The70%power commitmentisan administrativerestrictionproposedbySCEbasedonthe operating assessmentsfortheoperatingperiod.Oncemade,this commitment becomespartoftheSCEUnit2 CurrentLicensingBasis.TheNRCdefinesCurrentLicensingBasis(CLB)in 10CFR54.3asfollows:Currentlicensingbasis(CLB)isthesetofNRC requirements applicable toaspecificplantanda licensee's written commitmentsforensuring compliancewithandoperationwithin applicable NRC requirementsandthe plant-specific design basis (including all modifications and additionstosuch commitmentsoverthelifeofthelicense)thataredocketedandineffect.AsaresultofSCE

's formal commitmentestablishedintheCALresponseandUnit2ReturntoServiceReport,the

."normal steadystatefullpower "inthe CurrentLicensingBasisforUnit2is70%powerfortheproposedoperatingperiod

.Sinceallofthe Operational Assessments (OAs)wereperformedfor operationatorabove70%power,TS5.5.2.11 compliance is demonstrated.

Operational Assessmentat100%RatedThermalPower(RTP)

Operational Assessments(OAs)areperformedin accordancewiththeSCESGProgramtoensureSGtube integrityandleakage integritywillbe maintainedduringthe operating periodpriortothenextplannedSGinspection.SCEprovideda numberofOAsforrestartofUnit2

.TheOAthat addresses tube wear mechanisms other than tube-to-tube wear (TTW)wasperformedat100%power.

ThreeadditionalOAswere performed independentlyusingdiversemethodstoaddressTTW.ThethreeOAs addressingTTWwere performedusingthe thermal-hydraulic conditions at70%power.AsrequestedintheRAI

,SCEwillprovideanOAthatincludesan evaluationofsteam generatorTTWforoperationuptotheRTP.ThisOAwillbeprovidedtotheNRCforreviewbyMarch15,2013.InthisOA,SCEwill supplementtheIntertekOA (Enclosure 2, Attachment 6, Appendix CoftheCALResponseLetter)whichisbasedon

'traditional' industry guidelines.TheOA supplement will demonstratethatthe Structural Integrity PerformanceCriteria(SIPC)andthe AccidentInducedLeakage Performance Criteria (AILPC)aresatisfiedfor100%RatedThermalPower(RTP).[New Commitment]Page6of7 TheremainingTTWOAswillcontinuetobeusedinourdecisiontorestrictoperationto70%power.TheseOAs demonstrate that sufficientmargintotheonsetoffluidelastic instabilityexistsat70%power.ActionstobetakenfollowingreturntoserviceforUnit2 SCE'sCALresponseprovidedseveralinterimactionsregardingoperationfortheinitial150dayperiodfollowingstartupfromthe current outage.Followingthatinitial150dayper iod, SCEintendstotakethefollowingactionsonaninterimbasisuntilalong-termpowerlevelforUnit2isestablished:

1.Operationwillbelimitedto70%powerunlessapprovalforahigherpowerlevelisobtainedfromtheNRC.IfSCErepairstheexistingsteam generatorsforUnit2 ,orifadditionaltube inspectionsoranalysesprovidenew information demonstrating thatUnit2isnot susceptibletoTTWbyin-planeFEIatahigherpowerlevel,SCE mayprovidetheNRCwith justification(s)foroperatingathigherpowerlevelsupto100%power.SCEwillnot operateUnit2atpowerlevelshigherthan70%untiltheNRChasauthorizedoperationathigherpowerlevels.2.Followingrestartfromthe currentoutage,operationofSONGSUnit2willberestrictedto150cumulativedaysofoperationatorabove15%ofRTPof3438MWt.After150daysofcumulative operationatorabove15%power,SCEw illshutdownUnit2foracyclesteam generatortubeinspectionoutageandwillperformtube inspections in accordance with Technical Specification5.5.2.11andSection8.3oftheUnit2ReturntoService(RTS)Report.Steam generatortubeinspectionsperformedduring subsequentinspectionoutageswillbe performedusingthesameinspectionscopeandmethods.3.Usingtheresultsofthetubeinspectionduringthefirst mid-cycleoutageduringCycle17,SCEwillprepareanupdatedOAforUnit2

.TheOAwillbeperformedforoperationat70%ofRTPandwill determinethedurationofthe subsequentoperatingperioduntilthenextinspectionoutage.Followingany subsequentoutagewithsteam generator tubeinspections,SCEwillupdatethisOAasneededtosupportoperationattheintendedpowerlevel.4.Ateachinspection

,SGtube wear indicationswillbeevaluatedin accordancewiththeConditionMonitoring requirementsoftheSONGS Technical Specifications and industry guidelinesforstructuralandleakageintegrity.ConfirmednewTTW indicationslegacy)orconfirmed increasesinsizeofexisting (previously identified)

TTW indicationswillbeassessedto determineiftheyaretheresultofin-planeFE!.SCEwillrestartUnit2whentheinspectionprogram demonstrates reasonable assurancethatTTWcausedbyin-planeFEIdidnotoccurandconditionmonitoring demonstrates tube integrity performancecriteriaaresatisfied.SCEwilloperateuptothesamepowerlevelallowedforthepreviousoperatingperiodandfortheintervalspecifiedintheupdatedOA.ThisupdatetotheOAwillbepreparedwithin90daysafterMode4entryasrequiredby industryguidelines.Ifin-planeFEIisobserved,SCEwillnotrestartUnit2 without specific discussionswiththeNRC.SCEintendstousetheabove approachuntilitdeterminesthelong-term operationallimitsfortheUnit2SG's.SCEwillinformtheNRCwhenthe determinationismadeof whetherUnit2canbereturnedto100%power operationorlong-termoperationatreducedpowerisneeded

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