ML17334B590
| ML17334B590 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 06/19/1996 |
| From: | FITZPATRICK E AMERICAN ELECTRIC POWER CO., INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML17333A478 | List: |
| References | |
| AEP:NRC:1166AA, GL-95-05, GL-95-5, NUDOCS 9606260254 | |
| Download: ML17334B590 (34) | |
Text
CATEGORY1REGULATO~INFORMATIONDISTRIBUTIONSYSTEM(RIDS)ACCESSIONNBR:9606260254DOC.DATE:96f06fl9NOTARIZED:YESDOCKET:FACIL:50-315DonaldC.CookNuclearPowerPlant,Unit1,IndianaM05000315AUTH.NAMEAUTHORAFFILIATIONFITZPATR:.CK,E.AmericanElectricPowerCo.,Inc.RECIP.NAMERECIPIENTAFFILIATIONDocument'ontrolBranch(DocumentControlDesk)SUBJE!T:ApplicationforamendtoLicenseDPR-58,addressingapplicablerequirementsofNRCGL95-05,"Voltage-BasedC.RepairCriteriaforRepairofWestinghouseSGTubesAffectedby,OutsideDiameterStressCorrosionCracking."ADISTRIBUTIONCODE:ADOIDCOPIESRECEIVED:LTRIENCL/SIZE:TITLE:ORSubmittal:GeneralDistributionENOTES:RECIPIENTIDCODE/NAMEPD3-1LAHICKMAN,JINTERNAL,~IEl.HE~NTE1%RR/DRCH~HICBNRR/DSSA/SRXBOGC/HDS2EXTERNAL:NOACCOPIESLTTRENCL11111111111011RECIPIENTIDCODE/NAMEPD3-1PDNRR/DE/EMCBNRR/DSSA/SPLBNUDOCS-ABSTRACTNRCPDRCOPIESLTTRENCL11111111D0NOTETOALL"RIDS"RECIPIENTS:PLEASEHELPUSTOREDUCEWASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMOWFN5D-5(EXT.415-2083)TOELIMINATEYOURNAMEFROMDISTRIBUTIONLISTSFORDOCUMENTSYOUDON'TNEED!ITOTALNUMBEROFCOPIESREQUIRED:LTTR,12ENCLll eRf4>~4.1~'l4,C AmericanElectricP~1RiversidePlazaColumbus,OH4321523736142231000June19,1996AEP:NRC:1166AADocketNos.:50-315U.S.NuclearRegulatoryCommissionATTN:DocumentControlDeskWashington,D.C.20555Gentlemen:DonaldC.CookNuclearPlantUnit1TECHNICALSPECIFICATIONCHANGESTOINCORPORATE2VOLTSTEAMGENERATORTUBESUPPORTPLATEREPAIRCRITERIONThisletteranditsattachmentsprovideapplicationforamendmenttothetechnicalspecifications(T/Ss)ofDonaldC.CookNuclearPlantUnit1.Specifically,thisinformationaddressestheapplicablerequirementsofNRCGenericLetter(GL)95-05"Voltage-BasedRepairCriteriafortheRepairofWestinghouseSteamGeneratorTubesAffectedbyOutsideDiameterStressCorrosionCracking."Attachment1providesatechnicalsummaryoft:hespecificinspectionpracticesandcalculationmethodologiesoutlinedinGL95-05andthe10CFR50.92nosignificanthazardsevaluation.Theevaluationandresultssupportcontinueduseofthe2voltpluggingcriteriaasallowedbyGL95-05forfutureoperatingcycles.Attachment2containsexistingT/Spagesmarkedtoreflecttherequestedchanges.Attachment3providestheproposedrevisedT/Spages.Webelievetheproposedchangeswillnotresultin(1)asignificantchangeinthetypesofanyeffluentthatmaybereleasedoffsite,or(2)asignificantincreaseinindividualorcumulativeoccupat.i.onalradiationexposure.9606260254';.960619'DRADOCK.050003i5P.PDR U.S.NuclearRegulatoryCommissionPage2AEP:NRC:1166AATheseproposedchangeshavebeenreviewedbythePlantNuclearSafetyReviewCommitteeandtheNuclearSafetyandDesignReviewCommittee.Incompliancewiththerequirementsof10CFR50.91(b)(1),copiesofthisletteranditsattachmentshavebeentransmittedtotheMichiganPublicServiceCommissionandtotheMichiganDepartmentofPublicHealth.Sincerely,VicePresidentSWORNTOANDSUBSCRIBEDBEFOREMETHIS~~~4DAYOF1996teryPublicllgAttachmentscc:A.A.BlindG.CharnoffH.J.MillerNFEMSectionChiefNRCResidentInspector-BridgmanJ.R.Padgett U.S.NuclearRegulatoryCommissionPage3AEP:NRC:1166AAbc:S.J.Brewer/M.S.Ackerman/K.J.TothJ.A.KobyraD.R.Hafer/J.R.JensenJ.B.ShinnockJ.S.WiebeJ.B.Hickman,NRC-Washington,D.C.-w/attachmentPRONET-w/attachmentDC-N-6015.1 J'
AmericanElectric1RiversidePlazaColumbus,OH4321523736142231000ANERlCAMELECfRICPOWERJune19,1996AEP:NRC:1166AADocketNos~:50-315U.S.NuclearRegulatoryCommissionATTN:DocumentControlDeskWashington,D.C.20555Gentlemen:DonaldC.CookNuclearPlantUnit1TECHNICALSPECIFICATIONCHANGESTOINCORPORATE2VOLTSTEAMGENERATORTUBESUPPORTPLATEREPAIRCRITERIONThisletteranditsattachmentsprovideapplicationforamendmenttothetechnicalspecifications(T/Ss)ofDonaldC.CookNuclearPlantUnit1.Specifically,thisinformationaddressestheapplicablerequirementsofNRCGenericLetter(GL)95-05"Voltage-BasedRepairCriteriafortheRepairofWestinghouseSteamGeneratorTubesAffectedbyOutsideDiameterStressCorrosionCracking."Attachment1providesatechnicalsummaryofthespecificinspectionpracticesandcalculationmethodologiesoutlinedinGL95-05andthe10CFR50.92nosignificanthazardsevaluation.Theevaluationandresultssupportcontinueduseofthe2voltpluggingcriteriaasallowedbyGL95-05forfutureoperatingcycles.Attachment2containsexistingT/Spagesmarkedtoreflecttherequestedchanges.Attachment3providestheproposedrevisedT/Spages.Webelievetheproposedchangeswillnotresultin(1)asignificantchangeinthetypesofanyeffluentthatmaybereleasedoffsite,or(2)asignificantincreaseinindividualorcumulativeoccupationalradiationexposure.
U.S.NuclearRegulatoryCommissionPage2AEP:NRC:1166AATheseproposedchangeshavebeenreviewedbythePlantNuclearSafetyReviewCommitteeandtheNuclearSafetyandDesignReviewCommittee.Incompliancewiththerequirementsof10CFR50.91(b)(l),copiesofthisletteranditsattachmentshavebeentransmittedtotheMichiganPublicServiceCommissionandtotheMichiganDepartmentofPublicHealth.Sincerely,PgM.~,xi)E.E.FitzpatrickVicePresidentSWOP'OANDSUBSCRIBEDBEFOREMETHIS~cP4'AYOF1996.CotaryPublicw"llgAttachmentscc:A.A.BlindG.CharnoffH.J~MillerNFEMSectionChiefNRCResidentInspector-BridgmanJ.R.Padgett U.S.NuclearRegulatoryCommissionPage3AEP:NRC:1166AAbc:S.J.Brewer/M.S.Ackerman/K.J.TothJ.A.KobyraD.R.HaEer/J.R.JensenJ.B.ShinnockJ.S.WiebeJ.B.Hickman,NRC-Washington,D.C.-w/attachmentPRONET-w/attachmentDC-N-6015.1 ATTACHMENT1TOAEP:NRC:1166AADESCRIPTIONOFCHANGESTOTHEDONALDC.COOKNUCLEARPLANTUNIT1TECHNICALSPECIFICATIONS10CFR50.92EVALUATION Attachment1toAEP:NRC:1166AAPage1INTRODUCTIONThisamendmentrequestproposesachangetoCookNuclearPlantUnit1steamgenerators(SG)T/Ss4.4.5.2,4.4.5.4,4.4'.5,3.4.6.2andBases3/4.4.5and3/4.4.6.2toallowuseofGL95-05voltage-basedSGtubesupportplate(TSP)pluggingcriteria.ThechangeallowsSGtubeswithbobbincoileddycurrentindicationslessthanorequalto2voltsatTSPintersectionstoremaininservice,regardlessoftheapparentdepthoftubewallpenetrationif,asaresult,theprojectedend-of-cycle(EOC)distributionofcrackindicationsisshowntoresultinprimary-to-secondaryleakagelessthan8.4gpminthefaultedloopduringapostulatedsteamlinebreak(SLB)event.Indicationsgreaterthan2voltsbutlessthanorequaltotheuppervoltagerepairlimit(VU<L)mayremaininserviceifamotorizedrotatingpancakecoil(MRPC)probeinspectiondoesnotdetectdegradation.TheVUgLwillbedeterminedeachoutageusingthemostrecent,NRC-approvedindustrytubeburstdatabasetodeterminethevoltagecorrespondingtothetubestructurallimit(VSL).ThisamendmentwouldreducethenumberofSGtubespluggedduetoindicationsatsupportplateintersections.ReducingthenumberofpluggedtubesprovidesALARAbenefitsandmaintainsreactorcoolantsystem(RCS)flowmargin.Assessmentreportsaddressingtheeffectivenessofthevoltage-basedpluggingcriteriamethodologyaredescribedinWCAP-13187,Revision0,whichwascompletedfollowingfuelcycles13and14.ThisinformationwasreportedinsubmittaldocumentsAEP:NRC:1166JandAEP:NRC:1166AC.ThereportsconcludedthatthevoltagedistributionfoundbyinspectionatEOC13andEOC14,in1994and1995,respectively,wereingoodagreementwiththeprojections'hevoltagegrowthratescontinuetobeverysmall.Noin-servicetubeswerefoundforwhichthebobbincoilvoltageexceededthe2voltpluggingcriteriarepairlimitatEOC13orEOC14.Consideringtheresultsoftheaforementionedreports,continueduseofthe2voltpluggingcriteriaisjustified.SimilarassessmentandprojectionreportsbasedonGL95-05reportingrequirementswillbepreparedateachEOC.
Attachment1toAEP:NRC:1166AAPage2APPLICATIONOFGL95-05TOTHECOOKNUCLEARPLANTUNIT1SG'ICENSEAMENDMENTTheCookNuclearPlantUnit1,2voltpluggingcriteriawillbeimplementedpertheguidanceofGL95-05alongwiththelatestindustrydatafortubeburstandleakage.NRCGL95-05willbefactoredintotheCookNuclearPlantUnit1pluggingcriteriaasfollows:Analystswillbebriefedregardingthepossibilityofprimarywaterstresscorrosioncracking(PWSCC)atTSPintersections.IfPWSCCisfoundatthesupportplateintersectionsitwillbereportedtotheNRCstaffpriortostartup.2)Theuseofsupportingdatasetsforcalculationofburstprobabilityandestimationofprimary-to-secondaryleakageduringapostulatedmainSLBforeachoutagewillbebasedonthemostcurrent,NRC-approvedindustrydatabase.ThelatestindustrydatabasewastransmittedtotheNRCunderBeaverValleyPowerStation',Unit1,March27,1996,lettertransmittingsupplementalinformationinsupportofarequestedT/Schange,foravoltage-basedSGtuberepaircriteria,originallyproposedintheirletterdatedDecember7,1995.Thatdatabasewasusedinthepreparationofthissubmittal.3)MainsteamlineburstprobabilityandleakagecalculationswillbeperformedfollowingtheguidanceofGL95-05,Section2,"TubeIntegrityEvaluation."Calculationsperformedinsupportofthevoltage-basedrepaircriteriawillfollowthemethodologydescribedinWCAP-14277,"SteamLineBreakLeakRateandTubeBurstProbabilityAnalysisMethodsforOutsideDiameterStressCorrosionCrackingatTubeSupportPlateIntersections,'"datedJanuary1995.Thecalculations,usingtheas-foundvoltagedistribution,willbeperformedpriortoreturningtheSGstoservice.TheprojectedEOCvoltagedistributionresultswillbereportedinthe90dayreport.4)Inspectionscope,dataacquisition,anddataanalysiswillbeperformedfollowingtheguidanceofGL95-05,Section3,"InspectionCriteria"andreferencedAppendixA,'DEDataAcquisitionandAnalysisGuidelines."AnMRPCinspectionwillbedoneonallindicationsexceeding2volts.AnMRPCinspectionwillalsobedoneonallintersectionswherecoppersignals,largemixedresiduals,ordentslargerthan5voltsinterferewithdetectionofflaws.
II Attachment1toAEP:NRC:1166AAPage3Probewearinspectionsandre-inspectionswillbeperformedusingthefolloOingguidelines:Ifanyofthelastprobewearstandardsignalamplitudes,priortoprobereplacement,exceedthe215Xlimitbyavalueof"XX,"thenanyindicationsmeasuredsincethelastacceptableprobewearmeasurementthatarewithin"XX"oftheplugginglimitwillbereinspectedwiththenewprobe.Forexample,ifanyofthelastprobewearsignalamplitudespriortoprobereplacementwere17Xaboveorbelowtheinitialamplitude,thentheindicationsthatarewithin2X(17X-15X)oftheplugginglimitmustbereinspectedwiththenewprobe.Alternatively,thevoltagecriterionmaybeloweredtocompensatefortheexcessvariation;forthecaseabove,amplitudes)0.98timesthevoltagecriterioncouldbesubjecttorepair.5)TuberemovalandexaminationwillbeperformedbasedontheguidancecontainedinGL95-05,Section4,"TubeRemovalandExamination/Testing."Plansaretopullatubespecimenwithatleasttwointersectionsduringthe1997refuelingoutage.6)ApplicationofGL95-05,Section5,"OperationalLeakageRequirements,"wi,llbecontinued.TheSGtubeleakagelimitof150gallonsperdaythrougheachSGwillbemaintainedaspreviouslyapprovedbytheNRCforourpresentfuelcycle.CookNuclearPlantleakagemonitoringmethodsprovidetimelyleakdetection,trending,andresponsetorapidlyincreasingleaks.7)GL95-05,Section6,"ReportingRequirements,"willbeimplemented.AsstatedpreviouslyforSection2,thecalculationofleakageandburstprobabilityrequiredpriortoreturningtheSGstoservicewillbeperformedusingoftheas-foundEOCvoltagedistribution.
hh0 Attachment1toAEP:NRC:1166AAPage4III.AEPCOMMENTSTOGL95-05ANDASSOCIATEDIMPACTTOAEPLICENSEAMENDMENTREUESTFORSGPLUGGINGCRITERIA1)GL95-05,Sectionl.b:AnalysesperformedbyWestinghousehaveshownthatnotubesintheCookNuclearPlantUnit1SGswouldbesubjecttocollapseduringalossofcoolantaccident(LOCA)plussafeshutdownearthquake(SSE)eventsTherefore,notubesareexcludedbasedonthiscriteria.Series51SGs,designedbyWestinghouse,donothaveflowdistributionbaffleplates;therefore,Sectionl.b.5isnotapplicable.2)GL95-05,Section3.c.3:Therequirementtoreinspectalltubespriortothelastprobechangeoutifthewearmeasurementexceeds15/isunnecessary.Reinspectionofindicationsnecessitatedbyout-of-specificationprobewearwillbeconductedaccordingtoitem4ofpage2ofthisattachment.IV.10CFR5092EVALUATIONBACKGROUNDCookNuclearPlantUnit1T/SAmendment200permittedtheimplementationofa2voltSGtubepluggingcriteria.Thatlicenseamendment,applicableonlyforthecurrentoperatingcycle(cycle15),requirestherepairofflaw-likebobbinindicationsabove2volts.Weareproposinguseofasimilar2voltrepaircriterionwithoutthecycle-specificlimitation.TheproposedpluggingcriteriaprogramfortheCookNuclearPlantUnit1SGsfollowstheguidanceandgeneralintentofGL95-05tomaintaintubestructuralandleakageintegrity.DESCRIPTIONOFTHEPLUGGINGCRITERIAREQUESTAsrequiredby10CFR50.91(a)(1),ananalysisisprovidedtodemonstratethattheproposedlicenseamendmenttoimplementapluggingcriteriafortheTSPelevationOutsideDiameterStressCorrosionCracking(ODSCC)occurringintheCookNuclearPlantUnit1SGsinvolvesanosignificanthazardsconsideration.Thepluggingcriteriautilizescorrelationsbetweeneddycurrentbobbincoilprobesignalamplitude(voltage)andtubeburstandleakagecapability.ThepluggingcriterionisbasedontestingoflaboratoryinducedODSCCspecimensandonextensiveexaminationof Attachment1toAEP:NRC:1166AAPage5pulledtubesfromoperatingSGs(industrywide--includingthreetubespulledin1992'epresentingnineintersectionsfromCookNuclearPlantUnit1).ConsistentwithGL95-05,thepluggingcriteriaprogramforCookNuclearPlantUnit1willincludethefollowingelementsaslistedunder"1.OverviewoftheVoltageRepairLimitApproach,"page3ofGL95-05.Performanenhancedinspectionoftubes,particularlyattheTSPintersections.A100KbobbincoilinspectionofhotlegTSPintersectionsandcoldlegintersections,downtothelowestcoldlegsupportplatewithknownODSCCindications,willbeperformed.Allflawindicationswithbobbinvoltagesgreaterthan2voltswillbeinspectedbyMRPC.UtilizeNondestructiveExamination(NDE)dataacquisitionandanalysisproceduresthatareconsistentwiththemethodologyusedtodevelopthevoltage-basedrepairlimits.Theinspectionscope,dataaquisistion,anddata-analysiswillbeperformedusingtheguidanceofSection3oftheGL.Repairtubesthatexceedthevoltagelimits.Flaw-likesignalsadjacenttotheTSP,withbobbinvoltageslessthanorequalto2volts,willbeallowedtoremaininservice.Flaw-likeindicationsadjacenttotheTSP,withabobbinvoltageofgreaterthan2voltsbutlessthanorequaltouppervoltagerepairlimit,mayremaininserviceifMRPCinspectiondoesnotdetectaflaw.Flawindicationswithavoltageofgreaterthantheuppervoltagerepairlimitwillberepaired.DeterminetheBeginningofCycle(BOC)voltagedistribution.BeginningofCyclevoltagedistributionwillbeestablishedfromtheactualtubeinspectionstobeperformedandwillbeestablishedusingcurrentprogrammethodology.ProjecttheEOCdistribution.AnEOCvoltagedistributionwillbeestablishedbasedontheEOCeddycurrenttestdata.EOCvoltagedistributionwillbeprojectedusingMonteCarlotechniquesasdescribedinWCAP-hI1 Attachment1toAEP:NRC:1166AAPage614277andwillincludeallowanceforeddycurrentuncertaintyasdefinedinGL95-05andaconservativevoltagegrowthrateallowance.FortheprojectedEOCvoltagedistribution,calculateboththeprimary-to-secondaryleakageunderpostulatedaccidentconditionsandtheconditionaltubeburstprobability.Asanalternative,theactualmeasuredEOCvoltagedistributioncanbeusedwhenitisimpracticaltocompletethe,projectedEOCcalculationpriortoreturningtheSGstoserviceforthepurposeofdeterminingwhetherthereportingcriteriainGI95-05Sections6.a.land6.a.3apply.Steamlinebreakleakagewillbecalculated,asdescribedinWCAP-14277,basedontheEOCprojectedvoltagedistribution.Projectedleakagemustremainbelow8.4gpminthefaultedloopforpermissibleoffsitedoseestimatestoremainacceptablewithin10Xofthe10CFR100guidelines.The8.4gpmleakageforoffsitedoseestimatesissmallerthantheleakagenumbercalculatedforacceptablecontrolroomdoseperGeneralDesignCriteria(GDC)19.Therefore,theoffsitedoseismorelimiting.ConditionaltubeburstprobabilitywillbecalculatedaccordingtothemethodologydescribedinWCAP-14277.ConsistentwithGL95-05,ifburstprobabilityisfoundtobegreaterthan1x10~theNRCwillbeconsulted.AsprescribedinGL95-05,anevaluationofprimary-to-secondaryleakage(andsubsequentlyoffsitedose)isrequiredforallplantsimplementingthepluggingcriteria.AllbobbincoilindicationsareincludedintheSLBleakageanalyses,alongwithconsiderationoftheprobabilityofdetection.Iftheprojectedleakageexceeds8.4gpminthefaultedloopduringapostulatedSLBevent,thenumberofindicationstowhichthepluggingcriteriaareappliedisreduced,throughtuberepair,untiltheprimary-to-secondaryleakagelimitsaresatisfied.EVALUATIONTubeDegradationCharacterizationIngeneral,thedegradationmorphologyoccurringattheTSPintersectionsatplantsintheU.S.canbedescribedasaxiallyorientedODSCC.ThedegradationmorphologyatCookNuclearPlantUnit1isentirelycompatiblewiththeoverallindustrydatabase.
Attachment1toAEP:NRC:1166AAPage7SteamGeneratorTubeIntegrityInthedevelopmentofapluggingcriteriaforCookNuclearPlantUnit1,RegulatoryGuide(RG)1.121,"BasesforPluggingDegradedPWRSteamGeneratorTubes"andRGl.'83,"In-serviceInspectionofPWRSteamGeneratorTubes"areusedasthebasesfordeterminingthatSGtubeintegrityismaintainedwithinacceptablelimits.RegulatoryGuide1.121describesamethodacceptabletotheNRCstaffformeetingGDC14,15,31,and32byreducingtheprobabilityandconsequencesofSGtuberupturebydeterminingthelimitingsafeconditionsoftubewalldegradationbeyondwhichtubeswithunacceptablecracking,asestablishedbyin-serviceinspection,shouldberemovedfromservicebyplugging.ThisregulatoryguideusessafetyfactorsonloadsfortubeburststhatareconsistentwiththerequirementsofSectionIIIoftheASMECode.FortheTSPelevationdegradationoccurringintheCookNuclearPlantUnit1SGs,tubeburstcriteriaareinherentlysatisfiedduringnormaloperatingconditionsbythepresenceoftheTSP.ThepresenceoftheTSPenhancestheintegrityofthedegradedtubesinthatregionbyprecludingtubedeformationbeyondthediameterofthedrilledhole,thusprecludingtubeburst.Conservatively,nocreditistakeninthedevelopmentofthepluggingcriteriaforthepresenceoftheTSPduringaccidentconditions.Basedontheexistingdatabasefor7/8inchtubing,bursttestingindicatesthatthesafetyrequirementsfortubeburstmarginsduringaccidentconditionloadingcanbesatisfiedwithEOCbobbincoilsignalamplitudeslessthan8.8volts,regardlessofthedepthoftubewallpenetrationofthecracking.Uponimplementationoftheproposedpluggingcriteriaprogram,tubeleakageconsiderationsmustalsobeaddressed.Itmustbedeterminedthatthecrackswillnotleakexcessivelyduri~gallplantconditions.Forthe2voltinterimtubepluggingcriteriadevelopedfortheCookNuclearPlantUnit1SGtubes,noleakageisanticipatedduringnormaloperatingconditionsevenwiththepresenceofpotentialthroughwallcracks.Noprimary-to-secondaryleakageattheTSPhasbeendetectedinU.S.plants.Relativetotheexpectedleakageduringaccidentconditionloading,thelimitingeventwithrespecttodifferentialpressureexperiencedacrosstheSGtubesisapostulatedSLBevent.For7/8inchtubing,pulledtubedatasupportsnoleakageupto2.81voltsandlowprobabilityofleakagebetween2.81and6.0volts,forbothpulledtubesandmodelboilerspecimens,attheboundingSLBpressuredifferentialof2560psi.Steamlinebreakprimary-to-secondaryleakagewillbecalculatedasprescribedinGL95-05andWCAP14277,usingprojectedEOCeddycurrentdata.Thiscalculatedleakagemustbeshowntobelessthan8.4gpminthefaultedloop.
I Attachment1toAEP:NRC:1166AAPage8AdditionalConsiderations~*Theproposedamendmentwouldprecludeoccupationalradiationexposurethatwouldotherwisebeincurredbypersonnelinvolvedintubepluggingorrepairoperations.Byreducingnon-essentialtubeplugging,theproposedamendmentwouldminimizethelossofmargininthereactorcoolantflow,throughtheSGs,usedinLOCAanalyses.Theproposedamendmentwouldavoidlossofmargininreactorcoolantsystemflowand,therefore,assistinmaintainingminimumflowratesinexcessofthatrequiredforoperationatfullpower.ReductionintheamountoftuberepairrequiredcanreducethelengthofplantoutagesandreducethetimethattheSGsareopentothecontainmentenvironmentduringanoutage.A100Xeddycurrentbobbincoilprobeinspectionassociatedwithimplemen'tationofthepluggingcriteriaprogramwillhelptoidentifynewareasofconcernwhichmayarise,byprovidingalevelofin-serviceinspectionwhichisfarinexcessoftheT/Srequirementsutilizingthe40Xdepth-basedplugginglimitforacceptabletubewalldegradation.SIGNIFICANTHAZARDSANALYSISInaccordancewiththethreefactortestof10CFR50.92(c),implementationoftheproposedlicenseamendmentisanalyzedusingthefollowingstandardsandfoundnotto:1)involveasignificantincreaseintheprobabilityorconsequencesofanaccidentpreviouslyevaluated;2)createthepossibilityofanewordifferentkindofaccidentfromanyaccidentpreviouslyevaluated;or3)involveasignificantreductioninmarginofsafety.Conformanceoftheproposedamendmenttothestandardsforadeterminationofnosignificanthazardsasdefinedin10CFR50.92(threefactortest)isshowninthefollowingparagraphs:1)OperationofCookNuclearPlaneUnit1,inaccordancewiththeproposedlicenseamendment,doesnotinvolveasignificantincreaseintheprobabilityorconsequencesofanaccidentpreviouslyevaluated.Testingofmodelboilerspecimensforfreespantubing(noTSPrestraint)atroomtemperatureconditionsshowburstpressuresinexcessof5000psiforindicationsofouterdiameterstresscorrosioncrackingwithvoltagemeasurementsashighas19volts.BursttestingperformedonpulledtubesfromCookNuclearPlantUnit1withuptoa2.02voltindicationshowsmeasuredburstpressureinexcessof10,000psiatroomtemperature.Bursttestingperformedonpulledtubesfromotherplantsshowburstpressuresinexcessof5,300psiatroomtemperatures.Correctingfortheeffectsoftemperatureonmaterialpropertiesandminimumstrengthlevels(astheburst
Attachment1toAEP:NRC:1166AAPage9testingwasdoneatroomtemperature),tubeburstresistancesignificantlyexceedsthesafetyfactorrequirementsofRG1.121.Asstatedearlier,tubeburstcriteriaareinherentlysatisfiedduringnormaloperatingconditionsduetotheproximityoftheTSP.TestdataindicatesthattubeburstcannotoccurwithintheTSP,evenfortubeswhichhave100Xthroughwallelectric-dischargemachinednotches0.75inchlong,providedtheTSPisadjacenttothenotchedarea,Sincetube-to-tubesupportplateproximityprecludestubeburstduringnormaloperatingconditions,itfollowsthatuseoftheproposedpluggingcriteriamust,therefore,retaintubeintegritycharacteristicswhichmaintaintheRG1.121marginofsafetyof1.43timestheboundingfaultedcondition(steamlinebreak)pressuredifferential.DuringapostulatedmainSLB,theTSPhasthepotentialtodeflectduringblowdown,therebyuncoveringtheintersection.Basedontheexistingdatabase,theRG1.121criterionrequiringmaintenanceofasafetyfactorof1.43timestheSLBpressuredifferentialontubeburstissatisfiedby7/8inchdiametertubingwithbobbincoilindicationswithsignalamplitudeslessthanV><,regardlessoftheindicateddepthmeasurement.A2voltpluggingcriteriacomparesfavorablywiththecurrentV><(8.8volt)structurallimit,consideringthepreviouslycalculatedgrowthratesforODSCCwithinCookNuclearPlantUnit1SGs.Consideringavoltagegrowthcomponentof0.8volts(40Xvoltagegrowthbasedon2voltsBOC)andanondestructiveexaminationuncertaintyof0.40volts(20Xvoltageuncertaintybasedon2voltsBOC),whenaddedtotheBOCpluggingcriteriaof2volts,resultsinaboundingEOCvoltageofapproximately3.2voltsforacycleoperation.A5.6voltsafetymarginexists(8.8-3.2voltEOC-5.6voltmargin).Forthevoltage/burstcorrelation,theEOCstructurallimitissupportedbyavoltageof8.8volts.UsingthisVz<of8.8volts,aBOCmaximumallowablerepairlimitcanbeestablishedusingtheguidanceofRG1.121.TheBOCmaximumallowablerepairlimitshouldnotpermitasignificantnumberofEOCindicationstoexceedtheVz<andshouldassurethatacceptabletubeburstprobabilitiesareattained.ByaddingNDEuncertaintyallowancesandanallowanceforcrackgrowthtotherepairlimit,thestructurallimitcanbevalidated.ThepreviouspluggingcriteriasubmittalestablishedtheconservativeNDEuncertaintylimit(V<><)of20XoftheBOCrepair-limit.Forconsistency,a40Xvoltagegrowthallowance(V<<)totheBOCrepairlimitisalsoincluded.ThisallowanceisextremelyconservativeforCookNuclear
Attachment1toAEP:NRC:1166AAPage10PlantUnit1.Therefore,themaximumallowableuppervoltagerepairlimitV<<<forBOC,basedontheV><of8.8volts,canberepresentedbytheexpression:VURL+(VADExVURL)+(VMxVuRL)=8.8volts,or,themaximumallowableBOCrepairlimitcanbeexpressedas,Vz<<=8.8voltstructurallimit/1.6=5.5volts.Thisstructuralrepairlimitsupportsthisapplicationforpluggingcriteriaimplementationtorepairbobbinindicationsgreaterthan2voltsbasedonRPCconfirmationoftheindication.Conservatively,anupperlimitof5.5voltswillbeusedtorepairbobbincoilindicationswhichareabove2voltsbutdonothaveconfirmingRPCcalls.Relativetotheexpectedleakageduringaccidentconditionloadings,ithasbeenpreviouslyestablishedthatapostulatedmainSLBoutsideofcontainment,butupstreamofthemainsteamisolationvalve,representsthemostlimitingradiologicalconditionrelativetothepluggingcriteria.Insupportofimplementationofthepluggingcriteria,itwillbedeterminedwhetherthedistributionofcrackindicationsattheTSPintersectionsattheEOCareprojectedtobesuchthatprimary-to-secondaryleakagewouldresultinsiteboundarydoseswithinasmallfractionofthe10CFR100guidelines.AseparatecalculationhasdeterminedthisallowableSLBleakagelimittobe8.4gpm.AlthoughnotrequiredbytheCookNuclearPlantdesignbasis,thiscalculationusestherecommendedIodine-131transientspikingvaluesconsistentwithNUREG-0800,andtheT/Sreactorcoolantsystemactivitylimi,tof1microcuriepergramdoseequivalentIodine-131.Controlroomdosecalculationswerealsoperformedandfoundtobelesslimitingthantheoffsitedosecalculationleakrate.Therefore,themoreconservativeoffsitedoseleakrateisused.TheprojectedSLBleakageratecalculationmethodologyprescribedinGL95-05andWCAP14277willbeusedtocalculateEOCleakage,basedonactualEOCdistributionsandEOCprojecteddistributions.DuetotherelativelylowvoltagegrowthratesatCookNuclearPlantUnit1andtherelativelysmallnumberofindicationsaffectedbythepluggingcriteria,SLBleakagepredictionperGL95-05isexpectedtobesignificantlylessthanthepermissiblelevel.of8.4gpminthefaultedloop.Theinclusionofallintersectionsintheleakagemodel,alongwithapplicationofaprobabilityofdetectionof0.6,
Attachment1toAEP:NRC:1166AAPage11willresultinextremelyconservativeleakageestimations.Closeexaminat'ionoftheavailabledatashowsthatindicationsoflessthan2.8voltswillnotbeexpectedtoleakduringSLBconditions.TheproposedamendmentdoesnotresultinanyincreaseintheprobabilityorconsequencesofanaccidentpreviouslyevaluatedwithintheCookNuclearPlantUnit1FinalSafetyAnalysisReport(FSAR).2)Theproposedlicenseamendmentdoesnotcreatethepossibilityofanewordifferentkindofaccidentfromanyaccidentpreviouslyevaluated.ImplementationoftheproposedSGtubepluggingcriteriadoesnotintroduceanysignificantchangestotheplantdesignbasis.UseofthecriteriadoesnotprovideamechanismwhichcouldresultinanaccidentoutsideoftheregionoftheTSPelevations.Neitherasinglenoramultipletuberuptureeventwould,underanyplantconditions,beexpectedinaSGinwhichthepluggingcriteriahasbeenapplied.Specifically,wewillcontinuetoimplementamaximumleakageratelimitof150gpd(0.1gpm)perSGtohelpprecludethepotentialforexcessiveleakageduringallplantconditions.TheT/Slimitsimposedonprimary-to-secondaryleakageatoperatingconditionsareamaximumof0.4gpm(600gpd)forallSGswithamaximumof150gpdallowedforanyoneSG~TheRG1.121criteriaforestablishingoperationalleakageratelimitsthatrequireplantshutdownarebaseduponleak-before-break(LBB)considerationstodetectafreespancrackbeforepotentialtuberuptureduringfaultedplantconditions.The150gpdlimitshouldprovideforleakagedetectionandplantshutdownintheeventoftheoccurrenceofanunexpectedsinglecrackresultinginleakagethatisassociatedwiththelongestpermissiblecracklength.RegulatoryGuide1.121acceptancecriteriaforestablishingoperatingleakagelimitsarebasedonLBBconsiderationssuchthatplantshutdownisinitiatediftheleakageassociatedwiththelongestpermissiblecrack,isexceeded.Thelongestpermissiblecrackisthelengththatprovidesafactorofsafetyof1.43againstburstingatfaultedconditionsmaximumpressuredifferential.Avoltageamplitudeof8.8voltsfortypicalODSCCcorrespondstomeetingthistubeburstrequirementatalower95/predictionlimitontheburstcorrelationcoupledwith95/95lowertolerancelimitmaterialproperties.Alternatecrackmorphologiescancorrespondto
Attachment1toAEP:NRC:1166AAPage128.8voltssothatauniquecracklengthisnotdefinedbytheburstpressure"versusvoltagecorrelation.Consequently,typicalburstpressureversusthrough-wallcracklengthcorrelationswereusedtodefinethe"longestpermissiblecrack"forevaluatingoperatingleakagelimits.Consistentwiththecycle13,14and15licenseamendmentrequestsforpluggingcriteria,andSection5ofEnclosure1oftheGL,operationalleakagelimitswillremainat150gpd.perSG.AxialcracksleakingatthislevelareexpectedtoprovideLBBprotectionatboththeSLBpressuredifferentialof2560psiand,whilenotpartofanyestablishedLBBmethodology,LBBprotectionwillalsobeprovidedatavalueof1.43timestheSLBpressuredifferential.Thus,the150gpdlimitprovidesforplantshutdownpriortoreachingcriticalcracklengthsforSLBconditions.Additionally,thisLBBevaluationassumesthattheentirecreviceareaisuncoveredduringblowdown.Partialuncoverywillprovidebenefittotheburstcapacityoftheintersection.3)Theproposedlicenseamendmentdoesnotinvolveasignificantreductioninmarginofsafety.Theuseofthevoltage-basedbobbinprobeinterimTSPelevationpluggingcriteriaatCookNuclearPlantUnit1isdemonstratedtomaintainSGtubeintegritycommensuratewiththecriteriaofRG1.121.RegulatoryGuide1~121describesamethodacceptabletotheNRCstaffformeetingGDC14,15,31,and32byreducingtheprobabilityortheconsequencesofSGtuberupture.ThisisaccomplishedbydeterminingthelimitingconditionsofdegradationofSGtubing,asestablishedbyin-serviceinspection,forwhichtubeswithunacceptablecrackingshouldberemovedfromservice.Uponimplementationofthecriteria,evenundertheworstcaseconditions,theoccurrenceofODSCCattheTSPelevationsisnotexpectedtoleadtoaSGtuberuptureeventduringnormal,orfaultedplantconditions.ItwillbeconfirmedbyanalysisandcalculationthatEOCdistributionofcrackindicationsattheTSPelevationswillresultinacceptableprimary-to-secondaryleakageduringallplantconditionsandthatradiologicalconsequencesarenotadverselyimpacted.InaddressingthecombinedeffectsofaLOCAandSSEontheSGcomponent(asrequiredbyGDC2),ithasbeendeterminedthattubecollapsemayoccurintheSGsatsomeplants.ThepostulatedtubecollapseresultsfromadeformationofTSPsasaresultoflateralloadsatthewedgesupportsattheperipheryoftheplate.Thelateralloadsresultfromthe l
Attachment1toAEP:NRC:1166AAPage13combinedeffectsoftheLOCArarefactionwaveandSSEloadings.Theresultingpressuredifferentialonthedeformedtubesmaythencausesomeofthetubestocollapse.TherearetwoissuesassociatedwithapostulatedSGtubecollapse.First,thecollapseofSGtubingreducestheRCSflowareathroughthetubes.ThereductioninflowareaincreasestheresistancetoflowofsteamfromthecoreduringaLOCAwhich,inturn,maypotentiallyincreasepeakcladtemperature.Second,thereisapotentialthatpartialthrough-wallcracksintubescouldprogresstothrough-wallcracksduringtubedeformationorcollapse.Consequently,sincetheLBBmethodologyisapplicabletotheCookNuclearPlantUnit1reactorcoolantlooppiping,theprobabilityofbreaksintheprimarylooppipingissufficientlylowthattheyneednotbeconsideredinthestructuraldesignoftheplant.ThelimitingLOCAeventbecomeseithertheaccumulatorlinebreakorthepressurizersurgelinebreak.LossofcoolantaccidentloadsfortheprimarypipebreakswereusedtoboundtheCookNuclearPlantUnit1smallerbreaks.TheresultsoftheanalysisusingthelargerbreakinputsshowthattheLOCAloadswerefoundtobeofinsufficientmagnitudetoresultinSGtubecollapseorsignificantdeformation.AddressingRG1.83considerations,implementationof,thebobbincoilprobe,voltage-basedinterimtubepluggingcriteriaof2voltsissupplementedbyenhancededdycurrent,inspectionguidelinestoprovideconsistencyinvoltagenormalization,a100XeddycurrentinspectionsamplesizeattheTSPelevationsperT/S,andMRPCinspectionrequirementsforthelargerindicationsleftin-servicetocharacterizetheprincipaldegradationasODSCC.Asnotedpreviously,implementationoftheTSPelevationpluggingcriteriawilldecreasethenumberoftubeswhichmustberepaired.TheinstallationofSGtubeplugsreducestheRCSflowmargin.Thus,implementationofthepluggingcriteriawillmaintainthemarginofflowthatwouldotherwisebereducedintheeventofincreasedtubeplugging.Basedontheabove,itisconcludedthattheproposedlicenseamendmentrequestdoesnotresultinasignificantreductioninmarginwithrespecttoplantsafetyasdefinedintheFSARoranyBasesoftheplantT/Ss.
I,