ML17331B235

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Application for Amend to License DPR-58,incorporating 2.0 Volt Steam Generator Tube Support Plate Interim Plugging Criteria for Cycle 14
ML17331B235
Person / Time
Site: Cook American Electric Power icon.png
Issue date: 02/15/1994
From: FITZPATRICK E
INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To: MURLEY T E
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML17331B236 List:
References
AEP:NRC:1166L, NUDOCS 9402240387
Download: ML17331B235 (24)
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LERATEDDI,UTIONDEMONS'IONSYSTEMREGULATORYINFORMATIONDISTRIBUTIONSYSTEM(RIDS)ACCESSIONNBR:9402240387DOC.DATE:94/02/15NOTARIZED:YESDOCKETFACIL:50-315DonaldC.CookNuclearPowerPlant,Unit1,IndianaM05000315AUTH.NAMEAUTHORAFFILIATIONFITZPATRICK,E.IndianaMichiganPowerCo.(formerlyIndiana6MichiganEleRECIP.NAMERECIPIENTAFFILIATIONMURLEY,T.E.DocumentControlBranch(DocumentControlDesk)R

SUBJECT:

ApplicationforamendtoLicenseDPR-58,incorporating2.0voltsteamgeneratortubesupportplateinterimpluggingcriteriaforCycle14.DISTRIBUTIONCODE:A001DCOPIESRECEIVED:LTRENCLSIZETITLE:ORSubmittal:GeneralDistributionNOTES:RECIPIENTIDCODE/NAMEPD3-1LAHICKMAN,JINTERNALNRR/DE/EELBNRR/DRCH/HICBNRR/DSSA/SPLBNUDOCS-ABSTRACTOGC/HDS2EXTERNAL:NRCPDRCOPIESLTTRENCL1122111111111011RECIPIENTIDCODE/NAMEPD3-1PDNRR/DORS/OTSBNRR/DRPWNRR/DSSA/SRXB-e/"BPBCBEGFI01NSICCOPIESLTTRENCL11111111101111DDDNOTETOALL"RIDS"RECIPIENTS:DDPLEASEHELPUSTOREDUCEWASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMPl-37(EXT.20079)TOELIMINATEYOURNAMEFROMDISTRIBUTIONLINISFORDOCUMENTSYOUDON'TNEED!TOTALNUMBEROFCOPIESREQUIRED:LTTR16ENCL14 0414 IndianaNlchiganPowerCompanyP.O.Box16631Columbus,OH43216IAEP:NRC:1166LDonaldC.CookNuclearPlantUnit1DocketNo.50-315LicenseNo,DPR-58TECHNICALSPECIFICATIONCHANGESTOINCORPORATE2.0VOLTINTERIMSTEAMGENERATORTUBESUPPORTPLATEPLUGGINGCRITERIONFORFUELCYCLE14U.S.NuclearRegulatoryCommissionDocumentControlDeskWashington,D.C.20555Attn:T.EDMurleyFebruary15,1994

DearDr.Murley:

ThisletteranditsattachmentsconstituteanapplicationforanexigentamendmenttotheTechnicalSpecifications(T/Ss)fortheDonaldC.CookNuclearPlantUnit1,Specifically,wearerequestingtoincorporatea2.0voltsteamgeneratortubesupportplateinterimpluggingcriterionforFuelCycle14.AsdiscussedwithyourstaffonFebruary9,1994,thereasonformakingtherequestonanexigentbasisisthatthechangeisassociatedwithsteamgeneratorrepairsduringthecurrentUnit1refuelingoutage.TherepairsarecurrentlyscheduledtobeginMarch6,1994.Therefore,werequestapprovalofthisamendmentrequestbyMarch4inordertoavoidoutagedelays.ByletterdatedDecember15,1993(AEP:NRC:1166H),werequestedsimilarsteamgeneratortubeinterimpluggingcriteriaT/Schanges.Thisletterdoesnotsupersedetheprevioussubmittal.Thechangesdifferfromourprevioussubmittalinthatthissubmittalincorporatesa2.0voltcriterionversustheprevious1.0voltlimit.Theuppervoltagelimitfordispositionofindicationsbyrotatingpancakecoilinspectionisalsochangedfrom3.1voltsto3.6volts.Additionally,predictedend-of-cycleleakageinthefaultedloopforapostulatedsteamlinebreakislimitedto12.6gpm,versus1.0gpm.ThisisbasedonaradiologicalanalysisperformedinaccordancewiththeStandardReviewPlan,includingiodinespikingandT/Sreactorcoolantsystemactivitylimits.TheT/SchangesrequestedinthissubmittalaresimilartoaDecember9,1993,requestmadebytheFarleyNuclearPlantUnit1.9402240387940215PDRADOCK05000315I;.P.PDRgdOlI(I IIIpI Dr.T.E.Murley2AEP:NRC:1166LAsdiscussedwithyourstaffonFebruary9,arotatingpancakecoilinspectionwillbeperformedforalltubeswithanindicationabove1.0volt,despitethechangeintheinterimpluggingcriteriato2.0volts.Itisanticipatedthatthestandardbobbinprobe(0.720inches)willbetheprobeusedfortubepluggingdeterminationinconjunctionwiththeinterimpluggingcriteria.Ifasmallerbobbinprobeisused,itisourunderstandingthatitsusemustbesupportedbyarigorousstatisticalanalysis.Ifthesmallerbobbinprobeistobeused,thedetailsofthestatisticalanalysiswillbethesubjectofseparatecorrespondence.AsdiscussedinoursubmittalAEP:NRC:1166H,westatedourpositionregardingnotremovingtubesduringthe1994refuelingoutage.Changingtheinterimpluggingcriteriafrom1.0to2.0voltsdoesnotchangethebasisforourposition.Also,thatsubmittalprovidedanappendixentitled"NDEDataAcquisitionandAnalysisGuidelines."AlthoughthisappendixwaswrittenspecifictoanIPCof1.0volts,itisstillapplicableinthegeneralsensewithanIPCof2.0volts,andtherefore,perdiscussionswithyourstaffofFebruary9,1994,willnotberevisedforthisletter.Attachment1containsadescriptionoftheproposedT/Schangesaswellasthe10CFR50.92nosignificanthazardsevaluation.Attachment2containstheexistingT/Spagesmarkedtoreflectthechanges.Attachment3containstheproposedrevisedT/Spages.Attachment4containstheradiologicalanalysisthatsupportsthe12.6gpmend-of-cycleleakagelimitdiscussedabove.Webelievetheproposedchangeswillnotresultin(1)asignificantchangeinthetypesofanyeffluentthatmaybereleasedoffsite,or(2)asignificantincreaseinindividualorcumulativeoccupationalradiationexposure.TheseproposedchangeshavebeenreviewedbythePlantNuclearSafetyReviewCommitteeandbytheNuclearSafetyandDesignReviewCommittee.Incompliancewiththerequirementsof10CFR50.91(b)(l),copiesofthisletteranditsattachmentshavebeentransmittedtotheMichiganPublicServiceCommissionandtotheMichiganDepartmentofPublicHealth.Thisletterissubmittedpursuantto10CFR50.30(b),and,assuch,anoathstatementisattached.Sincerely,EFE.E.FitzpatrickVicePresident Dr.T.E.Murley3AEP:NRC:1166LdrAttachmentscc:A.A.BlindG.CharnoffJ.B.Martin-RegionIIINFEMSectionChiefNRCResidentInspectorJ.R.Padgett STATEOFOHIO)COUNTYOFFRANKLIN)E.E.Fitzpatrick,beingdulysworn,deposesandsaysthatheistheVicePresidentoflicenseeIndianaMichiganPowerCompany,thathehasreadtheforgoingTECHNICALSPECIFICATIONCHANGESTOINCORPORATE2.0VOLTINTERIMSTEAMGENERATORTUBESUPPORTPLATEPLUGGINGCRITERIONFORFUELCYCLE14andknowsthecontentsthereof;andthatsaidcontentsaretruetothebestofhisknowledgeandbelief.Subscribedandsworntobeforemethis/W~dayofNOTARYPUBLICRITAD.HILLSOTARYPUBLIC.STATOFOHIOaVCOhIh'IISSIOHEXPIRE-~X r4I/

ATTACHMENT1TOAEP:NRC:1166LDESCRIPTIONANDJUSTIFICATIONOFCHANGES10CFR50.92ANALYSISFORCHANGESTOTHEDONALDC.COOKNUCLEARPLANTUNIT1TECHNICALSPECIFICATIONS Attachment1toAEP:NRC:1166LPage1I.INTRODUCTIONThisamendmentrequestproposesachangetoT/S4.4.5(SteamGenerators)toincorporatearevisedcriterionforsteamgeneratortubesupportplateinterimpluggingcriterion(IPC).Thechangesallowsteamgeneratortubeswithindicationslessthanorequalto2.0voltstoremaininservice,regardlessofdepthoftubewallpenetration,ifasaresult,theprojectedend-of-cycle(EOC)distributionofcrackindicationsisverifiedtoresultinprimary-to-secondaryleakagelessthan12.6gpminthefaultedloopduringapostulatedsteamlinebreakevent.Indicationsgreaterthan2.0voltsbutlessthanorequalto3.6voltscanremaininserviceifarotatingpancakecoilprobe(RPC)inspectiondoesnotdetectdegradation.TheamendmentrequestisspecifictoFuelCycle14only.Thepurposeoftheamendmentistoreducethenumberoftubesrequiredtobeplugged.ThishasbenefitsbothfromanALARAperspectiveaswellastheperspectiveofmaximizingRCSflowmargin.A1.0voltIPCwasgrantedforCookNuclearPlantUnit1,viaT/SAmendment166,forthepreviousfuelcycle(Cycle13).ByletterdatedDecember15,1993(AEP:NRC:1166H),werequestedsimilarsteamgeneratortubeinterimpluggingcriteriaT/SchangesforCycle14.Thisletterdoesnotsupersedetheprevioussubmittal.Thechangesdifferfromourprevioussubmittalinthatthissubmittalincorporatesa2.0voltcriteriaversustheprevious.1.0voltlimit.TheuppervoltagelimitforRPCconfirmationischangedfrom3.1voltsto3.6volts.Additionally,predictedend-of-cycleleakageinthefaultedloopforapostulatedsteamlinebreakislimitedto12.6gpm,versus1.0gpm.Thisisbasedon'aradiologicalanalysisperformedinaccordancewiththeStandardReviewPlan,includingiodinespikingandT/Slimitsonreactorcoolantsystemactivity.(Theprevioussubmittaldidnotincludetheeffectsofiodinespikingonthedoseanalysisandassumedreactorcoolantactivitycorrespondingto1%failedfuel.)TheT/SchangesrequestedinthissubmittalaresimilartoaDecember9,1993,requestmadebytheFarleyNuclearPlantUnit1.AsdiscussedwithyourstaffonFebruary9,anRPCinspectionwillbeperformedforalltubeswithanindicationabove1.0volt,despitethechangeintheinterimpluggingcriteriafrom1.0voltto2.0volts.Itisanticipatedthatthestandardbobbinprobe(0.720inches)willbetheprobeusedfortubepluggingdeterminationinconjunctionwiththeinterimpluggingcriteria.Ifasmallerbobbinprobeisused,itisourunderstandingthatitsusemustbesupportedbyarigorousstatisticalanalysis.Ifthesmallerbobbinprobeistobeused,thedetailsofthestatisticalanalysiswillbethesubjectofseparatecorrespondence.

Attachment1toAEP:NRC:1166LPage2Our1.0voltIPCsubmittal(AEP:NRC:1166H)providedanappendixentitled"NDEDataAcquisitionandAnalysisGuidelines."AlthoughthisappendixwaswrittenspecifictoanIPCof1.0volt,itisstillapplicableinthegeneralsensewithanIPCof2.0volts,andtherefore,perdiscussionswithyourstaffofFebruary9,1994,willnotberevisedforthissubmittal.AssessmentofIPCMethodoloAnassessmentofthemethodologydescribedinWCAP-13187,Revision0willbeconductedfortheIPC.ItwilladdressdiscrepanciesbetweenpredictedandactualEOCvoltagedistributions.Theassessmentwillinclude:a.EOC12voltagedistribution-indicationsfoundduringtheinspectionregardlessofRPCverificationresults.b.Cycle12growthrate(i.e.frombeginningofcycle(BOC)12toEOC12).c~EOC12repairedindicationsvoltagedistributiondistributionofindicationspresentedin(a)abovethatwererepaired(ifpluggedorsleeved).d.VoltagedistributionforindicationsleftinserviceattheBOC13regardlessofRPCconfirmation-obtainedfrom(a)and(c)above.e.VoltagedistributionforindicationsleftinserviceattheBOC13thatwereconfirmedbyRPCtobecrack-likeornotRPCinspected.Non-destructiveexaminationuncertaintydistributionusedinpredictingtheEOC13voltagedistribution.goProjectedEOC13voltagedistributionusingthemethodologyinWCAP-13187,Revision0.h.ActualEOC13voltagedistribution-indicationsfoundduringtheinspectionregardlessofRPCconfirmation.Cycle13growthrate(i.e.fromBOC13toEOC13).EOC13repairedindicationsvoltagedistributiondistributionofindicationspresentedin(h)abovethatwererepaired(i.e.pluggedorsleeved).

Attachment1toAEP:NRC:1166LPage3k.VoltagedistributionforindicationsleftinserviceattheBOC14regardlessofRPCconfirmation-obtainedfrom(h)and(j)above.1.VoltagedistributionforindicationsleftinserviceattheBOC14thatwereconfirmedbyRPCtobecrack-likeornotRPCinspected.m.NondestructiveexaminationuncertaintydistributionusedinpredictingtheEOC14voltagedistribution.n.ProjectedEOC14voltagedistributionusingthemethodologyinWCAP-13187,Revision0.Thetotalassessment,(a)through(n)willbesubmittedapproximately10weeksfromcompletionofsteamgeneratorinspections.However,perT/SrequirementsthesteamlinebreakleakageanalysisperformedunderT/S4.4.5.4.a.10willbereportedtotheNRCStaffpriortorestartforFuelCycle14.II.SCTIONOFTHECHANGESTheproposedchangesarethosenecessarytoincorporatea2.0voltIPCforCookNuclearPlantUnit1FuelCycle14.Thespecificchangesareasfollows:1.TS4452d4455e3462cBases3445Bases34462ReferencetoFuelCycle13fortheIPCischangedtoFuelCycle14.ThedefinitionofIPCismodifiedsuchthatsteamgeneratortubeswithindicationslessthanorequalto2.0volts(vs.1.0volt)canremaininservice,regardlessofdepthoftubewallpenetration,ifasaresult,theprojectedend-of-cycledistributionofcrackindicationsisverifiedtoresultinprimary-to-secondaryleakagelessthan12.6gpm(vs.1.0gpm)inthefaultedloopduringapostulatedsteamlinebreakevent.Indicationsgreaterthan2.0voltsbutless'hanorequalto3.6volts(vs.1.0voltand4.0volts)canremaininserviceifaRPCinspectiondoesnotdetectdegradation.

Attachment1toAEP:NRC:1166LPage4Theend-of-cycleprimarytosecondaryleakagemustbelessthan12.6gpminthefaultedloop,versusthepresent1.0gpm,forapostulatedsteamlinebreakevent.Theleakageassumedintheaccidentanalysisischangedfrom120gpmto12.6gpm(fortheCycle14IPConly).III.10CFR5092EVALUATIONBACKGROUNDCookNuclearPlantUnit1T/SAmendment166permittedtheimplementationofa1.0voltsteamgeneratortubeinterimpluggingcriteria(IPC)forthe13thoperatingcycleoftheCookNuclearPlantUnit1steamgenerators.Thislicenseamendmentwasapplicableonlyforthepreviouscycle(Cycle13),andrequiredtherepairofflaw-likebobbinindicationsabove1.0volt.BasedupontubepullresultsfromCookNuclearPlantUnit1andotherplantsgatheredsincethestartofCycle13,weareproposinguseofa2.0voltinterimrepaircriterionfortheupcomingCycle14.DESCRIPTIONOFTHEIPCREQUESTAsrequiredby10CFR50.91(a)(l),ananalysisisprovidedtodemonstratethattheproposedlicenseamendmenttoimplementaninterimtubepluggingcriteriaforthetubesupportplateelevationouterdiameterstresscorrosioncracking(ODSCC)occurringintheCookNuclearPlantUnit1steamgeneratorsinvolvesanosignificanthazardsconsideration.TheIPCutilizescorrelationsbetweeneddycurrentbobbinprobesignalamplitude(voltage)andtubeburstandleakagecapability.ThepluggingcriteriaisbasedontestingoflaboratoryinducedODSCCspecimens,andextensiveexaminationofpulledtubesfromoperatingsteamgenerators(industrywideincluding3tubesrepresenting6intersectionsfromtheCookNuclearPlantUnit1steamgenerators.)Theinterimpluggingcriteriacanbedescribedbythefollowingelements:A1008bobbincoilinspectionofhotlegtubesupportplateintersectionsandcoldlegintersectionsdowntothelowestcoldlegtubesupportplatewithknownODSCCindicationswillbeperformed.2.Flaw-likesignalsadjacenttothetubesupportplateswithbobbinvoltageslessthanorequalto2.0voltswil'1beallowedtoremaininservice.

Attachment1toAEP:NRC:1166LPage53.Flaw-likesignalsadjacenttothetubesupportplatewithabobbinvoltageofgreaterthan2.0voltswillberepairedexceptasnotedinItem4.4.Flaw-likesignalsadjacenttothetubesupportplatewithabobbinvoltagegreaterthan2.0voltsbutlessthanorequalto3.6voltsmayremaininserviceifRPCinspectiondoesnotdetectaflaw.Flawindicationswithabobbinvoltagegreaterthan3.6voltswillberepaired.5.Aspartofasampleinspectionprogramtohelpensurethatadditionaldegradationmodesarenotoccurring,allflawindicationswithbobbinvoltagesgreaterthan1.0voltbutlessthanorequalto2.0voltswillbeinspectedbyRPC.6.Anend-of-cyclevoltagedistributionwillbeestablishedbasedupontheend-of-Cycle13eddycurrentdata.Baseduponthisdistribution,postulatedsteamlinebreakleakagewillbeestimatedbasedontheguidanceofdraftNUREG1477.Projectedleakagemustremainbelow12.6gpminthefaultedloopinorderforoffsitedoseestimatestoremainwithin10%ofthe10CFR100guidelines.AsprescribedindraftNUREG-1477,anevaluationofprimarytosecondaryleakage(andsubsequentlyoffsitedose)isrequiredforallplantsimplementingtheinterimpluggingcriteria(IPC).PerdraftNUREG-1477,allbobbinindicationsareincludedinthesteamlinebreakleakageanalysesalongwiththeconsiderationofprobabilityofdetection(POD).Iftheprojectedleakageexceeds12.6gpminthefaultedloopduringapostulatedsteamlinebreakevent,thenumberofindicationsinwhichtheinterimpluggingcriteriaareappliedisreducedthroughtuberepairuntiltheprimarytosecondaryleakagelimitsaresatisfied.EVALUATIONTubeDegradationCharacterizationIngeneral,thedegradationmorphologyoccurringatthetubesupportplateintersectionsatplantsintheU.S.canbedescribedasaxiallyorientedODSCC.ThedegradationmorphologyatCookNuclearPlantUnit1isentirelycompatiblewiththeoverallindustrydatabase.SteamGeneratorTubeIntegrityInthedevelopmentofaninterimpluggingcriteriaforCookNuclearPlantUnit1,RegulatoryGuide(RG)1.121,"BasesforPluggingDegradedPWRSteamGeneratorTubes"andRG1.83"InserviceInspectionofPWRSteamGeneratorTubes"areusedasthebasesfordeterminingthatsteam Attachment1toAEP:NRC:1166LPage6generatortubeintegrityconsiderationsaremaintainedwithinacceptablelimits.RG1.121describesamethodacceptabletotheNRCstaffformeetingGeneralDesignCriteria14,15,31,and32byreducingtheprobabilityandconsequencesofsteamgeneratortuberupturethroughdeterminingthelimitingsafeconditionsoftubewalldegradationbeyondwhichtubeswithunacceptablecracking,asestablishedbyinserviceinspection,shouldberemovedfromservicebyplugging.ThisregulatoryguideusessafetyfactorsonloadsfortubeburstthatareconsistentwiththerequirementsofSectionIIIoftheASMECode.ForthetubesupportplateelevationdegradationoccurringintheCookNuclearPlantUnit1steamgenerators,tubeburstcriteriaareinherentlysatisfiedduringnormaloperatingconditionsbythepresenceofthetubesupportplate.Thepresenceofthetubesupportplateenhancestheintegrityofthedegradedtubesinthatregionbyprecludingtubedeformationbeyondthediameterofthedrilledhole,thusprecludingtubeburst.Conservatively,nocreditistakeninthedevelopmentofthepluggingcriteriaforthepresenceofthetubesupportplateduringaccidentconditions.Basedontheexistingdatabasefor7/8inchtubing,bursttestingshowsthatthesafetyrequirementsfortubeburstmarginsduringaccidentconditionloadingscanbesatisfiedwithendofcyclebobbincoilsignalamplitudeslessthan9.6volts,regardlessofthedepthoftubewallpenetrationofthecracking.Uponimplementationofthepluggingcriteria,tubeleakageconsiderationsmustalsobeaddressed.Itmustbedeterminedthatthecrackswillnotleakexcessivelyduringallplantconditions.Forthe2.0voltinterimtubepluggingcriteriadevelopedfortheCookNuclearPlantUnit1steamgeneratortubes,noleakageisanticipatedduringnormaloperatingconditionsevenwiththepresenceofpotentiallythroughwallcracks.Noleakageduringnormaloperatingconditionshasbeenobservedinthefieldforcrackindicationswithsignalamplitudesupto7.7volts(3/4inchtubes).Voltagecorrelationto7/8inchtubingsizewouldresultinanexpectedvoltageofabout10volts.Noprimarytosecondaryleakageatthetubesupportplates(TSP)hasbeendetectedinU.S.plants.Relativetotheexpectedleakageduringaccidentconditionloadings,thelimitingeventwithrespecttodifferentialpressureexperiencedacrosstheSGtubesisapostulatedsteamlinebreakevent.For7/8inchtubing,pulledtubedatasupportsnoleakageupto2.81volts,andlowprobabilityofleakagebetween2.81and6.0volts,forbothpulledtubesandmodelboilerspecimensattheboundingsteamlinebreakpressuredifferentialof2560psi.SteamlinebreakprimarytosecondaryleakagewillbecalculatedasprescribedinSection3.3ofdraftNUREG-1477(usingaprimary-to-secondarypressuredifferentialof2560psid)onceEOC13eddycurrentdataisreduced.Thiscalculatedleakagemustbeshowntobelessthan12.6gpminthefaultedloop.

~~~~~Attachment1toAEP;NRC:1166LPage7AdditionalConsiderationsTheproposedamendmentwouldprecludeoccupationalradiationexposurethatwouldotherwisebeincurredbypersonnelinvolvedintubepluggingorrepairoperations.Byreducingnon-essentialtubeplugging,theproposedamendmentwouldminimizethelossofmargininthereactorcoolantflowthroughthesteamgeneratorinLOCAanalyses.Theproposedamendmentwouldavoidlossofmargininreactorcoolantsystemflowand,therefore,assistindemonstratingthatminimumflowratesaremaintainedinexcessofthatrequiredforoperationatfullpower.Reductionintheamountoftuberepairrequiredcanreducethelengthofplantoutagesandreducethetimethatthesteamgeneratorisopentothecontainmentenvironmentduringanoutage.The1008eddycurrentbobbinprobeinspectionassociatedwithimplementationoftheIPCwillhelptoidentifynewareasofconcernwhichmayarisebyprovidingalevelofinserviceinspectionwhichisfarinexcessoftheT/Srequirementsutilizingthe40$depth-basedplugginglimitforacceptabletubewalldegradation.SIGNIFICANTHAZARDSANALYSISInaccordancewiththethreefactortestof10CFR50,92(c),implementationoftheproposedlicenseamendmentisanalyzedusingthefollowingstandardsandfoundnotto1)involveasignificantincreaseintheprobabilityorconsequencesofanaccidentpreviouslyevaluated;2)createthepossibilityofanewordifferentkindofaccidentfromanyaccidentpreviouslyevaluated;or3)involveasignificantreductioninmarginofsafety.Conformanceoftheproposedamendmenttothestandardsforadeterminationofnosignificanthazardsasdefinedin10CFR50.92(threefactortest)isshowninthefollowing:1)OperationoftheDonaldC.CookNuclearPlantUnit1inaccordancewiththeproposedlicenseamendmentdoesnotinvolveasignificantincreaseintheprobabilityorconsequencesofanaccidentpreviouslyevaluated.Testingofmodelboilerspecimensforfreespantubing(notubesupportplaterestraint)atroomtemperatureconditionsshowburstpressuresinexcessof5000psiforindicationsofouterdiameterstresscorrosioncrackingwithvoltagemeasurementsashighas19volts.BursttestingperformedonpulledtubesfromCookNuclearPlantUnit1withuptoa2.02voltindicationshowsmeasuredburstpressureinexcessof10,000psiatroomtemperature,Bursttestingperformedonpulledtubesfromotherplantswithupto7.5voltindicationsshowburstpressuresinexcessof6,300psiatroomtemperatures.Correctingfortheeffectsoftemperatureonmaterialpropertiesandminimumstrengthlevels(asthebursttestingwasdoneatroomtemperature),tubeburstcapabilitysignificantlyexceedsthesafetyfactorrequirementsofRG1.121.Asstatedearlier,tubeburstcriteriaareinherentlysatisfiedduringnormaloperatingconditionsduetotheproximityofthetubesupportplate.Testdataindicatesthattubeburstcannotoccurwithinthetubesupport Attachment1toAEP:NRC:1166LPage8plate,evenfortubeswhichhave100%throughwallelectric-dischargemachined(EDM)notches0.75inchlong,providedthatthetubesupportplateisadjacenttothenotchedarea.Sincetubetotubesupportplateproximityprecludestubeburstduringnormaloperatingconditions,useofthecriteriamustretaintubeintegritycharacteristicswhichmaintainstheR.G.1.121marginofsafetyof1.43timestheboundingfaultedcondition(steamlinebreak)pressuredifferential.Duringapostulatedmainsteamlinebreak,theTSPhasthepotentialtodeflectduringblowdown,therebyuncoveringtheintersection.Basedontheexistingdatabase,theRG1.121criterionrequiringmaintenanceofasafetyfactorof1.43timesthesteamlinebreakpressuredifferentialontubeburstissatisfiedby7/8inchdiametertubingwithbobbincoilindicationswithsignalamplitudeslessthan9.6volts,regardlessoftheindicateddepthmeasurement.A2.0voltpluggingcriteriacomparesfavorablywiththe9.6voltstructurallimitconsideringthepreviouslycalculatedgrowthratesforODSCCwithintheCookNuclearPlantUnit1steamgenerators.Consideringavoltagegrowthcomponentof0,8volts(40%voltagegrowthbasedon2.0voltsBOC)andanNDEuncertaintyof0.40volts(20%voltageuncertaintybasedon2.0voltsBOC),whenaddedtotheBOCinterimpluggingcriteriaof2.0voltsresultsinaboundingEOCvoltageofapproximately3.2voltsforCycle14operation.A6.4voltsafetymarginexists(9.6structurallimit-3.2voltEOC-6.4voltmargin).Forthevoltage/burstcorrelation,theEOCstructurallimitissupportedbyavoltageof9.6volts.Usingthisstructurallimitof9.6volts,abeginningofcycle(BOC)maximumallowablerepairlimitcanbeestablishedusingtheguidanceofRG1.121.TheBOCmaximumallowablerepairlimitshouldnotpermittheexistenceofEOCindicationswhichexceedthe9.6voltstructurallimit.ByaddingNDEuncertaintyallowancesandanallowanceforcrackgrowthtotherepairlimit,thestructurallimitcanbevalidated.PreviousIPCsubmittalshaveestablishedtheconservativeNDEuncertaintylimitof20$oftheBOCrepairlimit.Forconsistency,a408voltagegrowthallowancetotheBOCrepairlimitisalsoincluded.ThisallowanceisextremelyconservativeforCookNuclearPlantUnit1.Therefore,themaximumallowableBOCrepairlimit(RL)basedonthestructurallimitof9.6voltscanberepresentedbytheexpression:RL+(0.2xRL)+(0.4xRL)-9.6volts,or,themaximumallowableBOCrepairlimit(RL)canbeexpressedas,RL9.6voltstructurallimit/1.66.0volts.ThisstructuralrepairlimitsupportsthisapplicationforCycle14IPCimplementationtorepairbobbinindicationsgreaterthan2.0voltsindependentofRPCconfirmationoftheindication.Conservatively,anupperlimitof3.6voltswillbeusedtoassesstubeintegrityforthose Attachment1toAEP:NRC:1166LPage9bobbinindicationswhichareabove2.0voltsbutdonothaveconfirmingRPCcalls.TheconservatismofthisrepairlimitisshownbytheEOC12(Summer1992)eddycurrentdata.Theoverallaveragevoltagegrowthwasdeterminedtobeonly2.2%(oftheBOCvoltage),witha12%averagevoltagegrowthforindicationslessthan1.0voltBOCanda1$averagevoltagegrowthforindicationsgreaterthan0.75voltsattheBOC.Inaddition,theEOC12maximumobservedvoltageincreasewasfoundtobe0.49volts,andoccurredinatubeinitiallylessthan1.0voltBOC.TheapplicabilityofCycle13growthratesforCycle14operationwillbeconfirmedpriortoreturntoserviceofCookNuclearPlantUnit1.Similarlargestructuralmarginsareanticipated.Relativetotheexpectedleakageduringaccidentconditionloadings,ithasbeenpreviouslyestablishedthatapostulatedmainsteamlinebreakoutsideofcontainmentbutupstreamofthemainsteamisolationvalverepresentsthemostlimitingradiologicalconditionrelativetotheIPC.Insupportofimplementationoftheinterimpluggingcriteria,itwillbedeterminedwhetherthedistributionofcrackindicationsatthetubesupportplateintersectionsattheendofCycle14areprojectedtobesuchthatprimarytosecondaryleakagewouldresultinsiteboundarydoseswithinasmallfractionofthe10CFR100guidelines.Aseparatecalculationhasdeterminedthisallowablesteamlinebreakleakagelimittobe12.6gpm.AlthoughnotrequiredbytheCookNuclearPlantdesignbasis,thiscalculationusestherecommendedIodine-131transientspikingvaluesconsistentwithNUREG-0800,andtheT/Sreactorcoolantsystemactivitylimitof1.0microcuriepergramdoseequivalentIodine-131.TheprojectedsteamlinebreakleakageratecalculationmethodologyprescribedinSection3.3ofdraftNUREG-1477willbeusedtocalculateEOC14leakage.DuetotherelativelylowvoltagegrowthratesatCookNuclearPlantUnit1andtherelativelysmallnumberofindicationsaffectedbytheIPC,steamlinebreakleakagepredictionperdraftNUREG<<1477isexpectedtobelessthantheacceptancelimitof12.6gpminthefaultedloop.Applicationofthecriteriarequirestheprojectionofpostulatedsteamlinebreakleakage,basedontheEOCvoltagedistribution.EOCvoltagedistributionisdevelopedusingEOC-13eddycurrentresultsandavoltagemeasurementuncertainty.Thedataindicatesthatathresholdvoltageof2.81voltswouldresultinthroughwallcrackslongenoughtoleakatsteamlinebreakconditions.DraftNUREG-1477requiresthatallindicationstowhichtheIPCareappliedmustbeincludedintheleakageprojection.TubepullresultsfromCookNuclearPlantUnit1indicatethattubewalldegradationofgreaterthan40%throughwallwasdetectableeitherbythebobbinorRPCprobe.Thetubewithmaximumthroughwallpenetrationof56%(42%average)hadavoltageof2.02volts.ThisindicationalsowasthelargestrecordedbobbinvoltagefromtheEOC12 Attachment1toAEP:NRC:1166LPage10leakageof2.81volts,inclusionofallIPCintersectionsintheleakagemodelisquiteconservative.Therefore,asimplementationofthe2.0voltinterimpluggingcriteriaduringCycle14doesnotadverselyaffectsteamgeneratortubeintegrityandresultsinacceptabledoseconsequencestheproposedamendmentdoesnotresultinanyincreaseintheprobabilityorconsequencesofanaccidentpreviouslyevaluatedwithintheCookNuclearPlantUnit1FSAR.2)Theproposedlicenseamendmentdoesnotcreatethepossibilityofanewordifferentkindofaccidentfromanyaccidentpreviouslyevaluated.Implementationoftheproposedsteamgeneratortubeinterimpluggingcriteriadoesnotintroduceanysignificantchangestotheplantdesignbasis.Useofthecriteriadoesnotprovideamechanismwhichcouldresultinanaccidentoutsideoftheregionofthetubesupportplateelevations;noODSCCisoccurringoutsidethethicknessofthetubesupportplates.Neitherasingleormultipletuberuptureeventwouldbeexpectedinasteamgeneratorinwhichthepluggingcriteriahasbeen.applied(duringallplantconditions).Specifically,wewillcontinuetoimplementamaximumleakageratelimitof150gpd(0.1gpm)persteamgeneratortohelpprecludethepotentialforexcessiveleakageduringallplantconditions.TheCycle14T/Slimitsonprimarytosecondaryleakageatoperatingconditionsisamaximumof0.4gpm(600gpd)forallsteamgenerators,or,amaximumof150gpdforanyonesteamgenerator.TheRG1.121criterionforestablishingoperationalleakageratelimitsthatrequireplantshutdownarebaseduponleak-before-breakconsiderationstodetectafreespancrackbeforepotentialtuberuptureduringfaultedplantconditions.The150gpdlimitshouldprovideforleakagedetectionandplantshutdownintheeventoftheoccurrenceofanunexpectedsinglecrackresultinginleakagethatisassociatedwiththelongestpermissiblecracklength.RG1.121acceptancecriteriaforestablishingoperatingleakagelimitsarebasedonleak-before-breakconsiderationssuchthatplantshutdownisinitiatediftheleakageassociatedwiththelongestpermissiblecrackisexceeded.Thelongestpermissiblecrackisthelengththatprovidesafactorofsafetyof1.43againstburstingatfaultedconditionsmaximumpressuredifferential.Avoltageamplitudeof9.6voltsfortypicalODSCCcorrespondstomeetingthistubeburstrequirementatalower95%predictionlimitontheburstcorrelationcoupledwith95/95lowertolerancelimit(LTL)materialproperties.Alternatecrackmorphologiescancorrespondto9.6voltssothatauniquecracklengthisnotdefinedbytheburstpressureversusvoltagecorrelation.Consequently,typicalburstpressureversusthrough-wallcracklengthcorrelationsareusedbelowtodefinethe"longestpermissiblecrack"forevaluatingoperatingleakagelimits.

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(~~~Attachment1toAEP:NRC:1166LPage11thatauniquecracklengthisnotdefinedbytheburstpressureversusvoltagecorrelation.Consequently,typicalburstpressureversusthrough-wallcracklengthcorrelationsareusedbelowtodefinethe"longestpermissiblecrack"forevaluatingoperatingleakagelimits.Thesinglethrough-wallcracklengthsthatresultintubeburstat1.43timesthesteamlinebreakpressuredifferential(1.43x2560psi-3660psi)andthesteamlinebreakpressuredifferentialalone(2560psi)areapproximately0.53inchand0.84inch,respectively.Aleakrateof150gpdwillprovidefordetectionof0.42inchlongcracksatnominalleakratesand0.61inchlongcracksatthelower95%confidencelevelleakrates.SincetubeburstisprecludedduringnormaloperationduetotheproximityoftheTSPtothetubeandthepotentialexistsforthecrevicetobecomeuncoveredduringsteamlinebreakconditions,theleakagefromthemaximumpermissiblecrackmustprecludetubeburstatsteamlinebreakconditions.Thus,the150gpdlimitprovidesforplantshutdownpriortoreachingcriticalcracklengthsforsteamlinebreakconditions.Additionally,thisleak-before-breakevaluationassumesthattheentirecreviceareaisuncoveredduringblowdown.Partialuncoverywillprovidebenefittot'eburstcapacityoftheintersection.3)Theproposedlicenseamendmentdoesnotinvolveasignificantreductioninmarginofsafety.TheuseofthevoltagebasedbobbinprobeinterimtubesupportplateelevationpluggingcriteriaatCookNuclearPlantUnit1isdemonstratedtomaintainsteamgeneratortubeintegritycommensuratewiththecriteriaofRG1.121.RG1.121describesamethodacceptabletotheNRCstaffformeetingGDCs14,15,31,and32byreducingtheprobabilityortheconsequencesofsteamgeneratortuberupture.Thisisaccomplishedbydeterminingthelimitingconditionsofdegradationofsteamgeneratortubing,asestablishedbyinserviceinspection,forwhichtubeswithunacceptablecrackingshouldberemovedfromservice.Uponimplementationofthecriteria,evenundertheworstcaseconditions,theoccurrenceofODSCCatthetubesupportplateelevationsisnotexpectedtoleadtoasteamgeneratortuberuptureeventduringnormalorfaultedplantconditions.TheEOC14distributionofcrackindicationsatt'etubesupportplateelevationswillbeconfirmedtoresultinacceptableprimarytosecondaryleakageduringallplantconditionsandthatradiologicalconsequencesarenotadverselyimpacted.Inaddressingthecombinedeffectsofalossofcoolantaccident(LOCA)+safeshutdownearthquake(SSE)onthesteamgeneratorcomponent(asrequiredbyGDC2),ithasbeendeterminedthattubecollapsemayoccurinthesteamgeneratorsatsomeplants.Thisisthecaseasthetubesupportplatesmaybecomedeformedasaresultoflateralloadsatthewedge

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Attachment1toAEP:NRC:1166LPage12supportsattheperipheryoftheplateduetothecombinedeffectsoftheLOCArarefactionwaveandSSEloadings.Then,theresultingpressuredifferentialonthedeformedtubesmaycausesomeofthetubestocollapse.Therearetwoissuesassociatedwithsteamgeneratortubecollapse.First,thecollapseofsteamgeneratortubingreducestheRCSflowareathroughthetubes.ThereductioninflowareaincreasestheresistancetoflowofsteamfromthecoreduringaLOCAwhich,inturn,maypotentiallyincreasePeakCladTemperature(PCT).Second,thereisapotentialthatpartialthrough-wallcracksintubescouldprogresstothrough-wallcracksduringtubedeformationorcollapse.Consequently,sincetheleak-before-breakmethodologyisapplicabletotheCookNuclearPlantUnit1reactorcoolantlooppiping,theprobabilityofbreaksintheprimarylooppipingissufficientlylowthattheyneednotbeconsideredinthestructuraldesignoftheplant.ThelimitingLOCAeventbecomeseithertheaccumulatorlinebreakorthepressurizersurgelinebreak.LOCAloadsfortheprimarypipebreakswereusedtoboundtheCookNuclearPlantUnit1smallerbreaks.TheresultsoftheanalysisusingthelargerbreakinputsshowthattheLOCAloadswerefoundtobeofinsufficientmagnitudetoresultinsteamgeneratortubecollapseorsignificantdeformation.AddressingRG1.83considerations,implementationofthebobbinprobevoltagebasedinterimtubepluggingcriteriaof2.0voltsissupplementedbyenhancededdycurrentinspectionguidelinestoprovideconsistencyinvoltagenormalization,a1008eddycurrentinspectionsamplesizeatthetubesupportplateelevationsperT/S,andRPCinspectionrequirementsforthelargerindicationsleftinservicetocharacterizetheprincipaldegradationasODSCC.'Asnotedpreviously,implementationofthetubesupportplateelevationpluggingcriteriawilldecreasethenumberoftubeswhichmustberepaired.TheinstallationofsteamgeneratortubeplugsreducestheRCSflowmargin.Thus,implementationoftheinterimpluggingcriteriawillmaintainthemarginofflowthatwouldotherwisebereducedintheeventofincreasedtubeplugging.Basedontheabove,itisconcludedthattheproposedlicenseamendmentrequestdoesnotresultinasignificantreductioninmarginwithrespecttoplantsafetyasdefinedintheFinalSafetyAnalysisReportoranyBasesoftheplantT/Ss.

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