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{{#Wiki_filter:CATEGORY1REGULATO~ | {{#Wiki_filter:CATEGORY1REGULATO~ | ||
INFORMATION DISTRIBUTION SYSTEM(RIDS)ACCESSION NBR:9606260254 DOC.DATE: | |||
U.S. | 96f06fl9NOTARIZED: | ||
YESDOCKET:FACIL:50-315 DonaldC.CookNuclearPowerPlant,Unit1,IndianaM05000315AUTH.NAMEAUTHORAFFILIATION FITZPATR:.CK,E. | |||
AmericanElectricPowerCo.,Inc.RECIP.NAME RECIPIENT AFFILIATION Document'ontrol Branch(Document ControlDesk)SUBJE!T:Application foramendtoLicenseDPR-58,addressing applicable requirements ofNRCGL95-05,"Voltage-Based C.RepairCriteriaforRepairofWestinghouse SGTubesAffectedby,OutsideDiameterStressCorrosion Cracking." | |||
ADISTRIBUTION CODE:ADOIDCOPIESRECEIVED:LTR IENCL/SIZE:TITLE:ORSubmittal: | |||
GeneralDistribution ENOTES:RECIPIENT IDCODE/NAME PD3-1LAHICKMAN,J INTERNAL,~IEl. | |||
HE~NTE1%RR/DRCH~HICB NRR/DSSA/SRXB OGC/HDS2EXTERNAL: | |||
NOACCOPIESLTTRENCL11111111111011RECIPIENT IDCODE/NAME PD3-1PDNRR/DE/EMCB NRR/DSSA/SPLB NUDOCS-ABSTRACT NRCPDRCOPIESLTTRENCL11111111D0NOTETOALL"RIDS"RECIPIENTS: | |||
PLEASEHELPUSTOREDUCEWASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMOWFN5D-5(EXT. | |||
415-2083) | |||
TOELIMINATE YOURNAMEFROMDISTRIBUTION LISTSFORDOCUMENTS YOUDON'TNEED!ITOTALNUMBEROFCOPIESREQUIRED: | |||
LTTR,12ENCLll eRf4>~4.1~'l4,C AmericanElectricP~1Riverside PlazaColumbus, OH4321523736142231000June19,1996AEP:NRC:1166AA DocketNos.:50-315U.S.NuclearRegulatory Commission ATTN:DocumentControlDeskWashington, D.C.20555Gentlemen: | |||
DonaldC.CookNuclearPlantUnit1TECHNICAL SPECIFICATION CHANGESTOINCORPORATE 2VOLTSTEAMGENERATOR TUBESUPPORTPLATEREPAIRCRITERION Thisletteranditsattachments provideapplication foramendment tothetechnical specifications (T/Ss)ofDonaldC.CookNuclearPlantUnit1.Specifically, thisinformation addresses theapplicable requirements ofNRCGenericLetter(GL)95-05"Voltage-BasedRepairCriteriafortheRepairofWestinghouse SteamGenerator TubesAffectedbyOutsideDiameterStressCorrosion Cracking." | |||
Attachment 1providesatechnical summaryoft:hespecificinspection practices andcalculation methodologies outlinedinGL95-05andthe10CFR50.92nosignificant hazardsevaluation. | |||
Theevaluation andresultssupportcontinued useofthe2voltpluggingcriteriaasallowedbyGL95-05forfutureoperating cycles.Attachment 2containsexistingT/Spagesmarkedtoreflecttherequested changes.Attachment 3providestheproposedrevisedT/Spages.Webelievetheproposedchangeswillnotresultin(1)asignificant changeinthetypesofanyeffluentthatmaybereleasedoffsite,or(2)asignificant increaseinindividual orcumulative occupat.i.onal radiation exposure. | |||
9606260254';.9606 19'DR''ADOCK.050003i5 P.PDR U.S.NuclearRegulatory Commission Page2AEP:NRC:1166AA TheseproposedchangeshavebeenreviewedbythePlantNuclearSafetyReviewCommittee andtheNuclearSafetyandDesignReviewCommittee. | |||
Incompliance withtherequirements of10CFR50.91(b)(1), | |||
copiesofthisletteranditsattachments havebeentransmitted totheMichiganPublicServiceCommission andtotheMichiganDepartment ofPublicHealth.Sincerely, VicePresident SWORNTOANDSUBSCRIBED BEFOREMETHIS~~~4DAYOF1996teryPublicllgAttachments cc:A.A.BlindG.CharnoffH.J.MillerNFEMSectionChiefNRCResidentInspector | |||
-BridgmanJ.R.Padgett U.S.NuclearRegulatory Commission Page3AEP:NRC:1166AA bc: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/attachment PRONET-w/attachment DC-N-6015.1 J' | |||
AmericanElectric1Riverside PlazaColumbus, OH4321523736142231000ANERlCAMELECfRICPOWERJune19,1996AEP:NRC:1166AA DocketNos~:50-315U.S.NuclearRegulatory Commission ATTN:DocumentControlDeskWashington, D.C.20555Gentlemen: | |||
DonaldC.CookNuclearPlantUnit1TECHNICAL SPECIFICATION CHANGESTOINCORPORATE 2VOLTSTEAMGENERATOR TUBESUPPORTPLATEREPAIRCRITERION Thisletteranditsattachments provideapplication foramendment tothetechnical specifications (T/Ss)ofDonaldC.CookNuclearPlantUnit1.Specifically, thisinformation addresses theapplicable requirements ofNRCGenericLetter(GL)95-05"Voltage-BasedRepairCriteriafortheRepairofWestinghouse SteamGenerator TubesAffectedbyOutsideDiameterStressCorrosion Cracking." | |||
Attachment 1providesatechnical summaryofthespecificinspection practices andcalculation methodologies outlinedinGL95-05andthe10CFR50.92nosignificant hazardsevaluation. | |||
Theevaluation andresultssupportcontinued useofthe2voltpluggingcriteriaasallowedbyGL95-05forfutureoperating cycles.Attachment 2containsexistingT/Spagesmarkedtoreflecttherequested changes.Attachment 3providestheproposedrevisedT/Spages.Webelievetheproposedchangeswillnotresultin(1)asignificant changeinthetypesofanyeffluentthatmaybereleasedoffsite,or(2)asignificant increaseinindividual orcumulative occupational radiation exposure. | |||
U.S.NuclearRegulatory Commission Page2AEP:NRC:1166AA TheseproposedchangeshavebeenreviewedbythePlantNuclearSafetyReviewCommittee andtheNuclearSafetyandDesignReviewCommittee. | |||
Incompliance withtherequirements of10CFR50.91(b)(l), | |||
copiesofthisletteranditsattachments havebeentransmitted totheMichiganPublicServiceCommission andtotheMichiganDepartment ofPublicHealth.Sincerely, PgM.~,xi) | |||
E.E.Fitzpatrick VicePresident SWOP'OANDSUBSCRIBED BEFOREMETHIS~cP4'AYOF1996.CotaryPublicw"llgAttachments cc:A.A.BlindG.CharnoffH.J~MillerNFEMSectionChiefNRCResidentInspector | |||
-BridgmanJ.R.Padgett U.S.NuclearRegulatory Commission Page3AEP:NRC:1166AA bc: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/attachment PRONET-w/attachment DC-N-6015.1 ATTACHMENT 1TOAEP:NRC:1166AA DESCRIPTION OFCHANGESTOTHEDONALDC.COOKNUCLEARPLANTUNIT1TECHNICAL SPECIFICATIONS 10CFR50.92EVALUATION Attachment 1toAEP:NRC:1166AA Page1INTRODUCTION Thisamendment requestproposesachangetoCookNuclearPlantUnit1steamgenerators (SG)T/Ss4.4.5.2,4.4.5.4,4.4'.5,3.4.6.2andBases3/4.4.5and3/4.4.6.2 toallowuseofGL95-05voltage-based SGtubesupportplate(TSP)pluggingcriteria. | |||
ThechangeallowsSGtubeswithbobbincoileddycurrentindications lessthanorequalto2voltsatTSPintersections toremaininservice,regardless oftheapparentdepthoftubewallpenetration if,asaresult,theprojected end-of-cycle (EOC)distribution ofcrackindications isshowntoresultinprimary-to-secondary leakagelessthan8.4gpminthefaultedloopduringapostulated steamlinebreak(SLB)event.Indications greaterthan2voltsbutlessthanorequaltotheuppervoltagerepairlimit(VU<L)mayremaininserviceifamotorized rotatingpancakecoil(MRPC)probeinspection doesnotdetectdegradation. | |||
TheVUgLwillbedetermined eachoutageusingthemostrecent,NRC-approved industrytubeburstdatabasetodetermine thevoltagecorresponding tothetubestructural limit(VSL).Thisamendment wouldreducethenumberofSGtubespluggedduetoindications atsupportplateintersections. | |||
ReducingthenumberofpluggedtubesprovidesALARAbenefitsandmaintains reactorcoolantsystem(RCS)flowmargin.Assessment reportsaddressing theeffectiveness ofthevoltage-based pluggingcriteriamethodology aredescribed inWCAP-13187, Revision0,whichwascompleted following fuelcycles13and14.Thisinformation wasreportedinsubmittal documents AEP:NRC:1166J andAEP:NRC:1166AC. | |||
Thereportsconcluded thatthevoltagedistribution foundbyinspection atEOC13andEOC14,in1994and1995,respectively, wereingoodagreement withtheprojections'he voltagegrowthratescontinuetobeverysmall.Noin-service tubeswerefoundforwhichthebobbincoilvoltageexceededthe2voltpluggingcriteriarepairlimitatEOC13orEOC14.Considering theresultsoftheaforementioned reports,continued useofthe2voltpluggingcriteriaisjustified. | |||
Similarassessment andprojection reportsbasedonGL95-05reporting requirements willbepreparedateachEOC. | |||
Attachment 1toAEP:NRC:1166AA Page2APPLICATION OFGL95-05TOTHECOOKNUCLEARPLANTUNIT1SG'ICENSE AMENDMENT TheCookNuclearPlantUnit1,2voltpluggingcriteriawillbeimplemented pertheguidanceofGL95-05alongwiththelatestindustrydatafortubeburstandleakage.NRCGL95-05willbefactoredintotheCookNuclearPlantUnit1pluggingcriteriaasfollows:Analystswillbebriefedregarding thepossibility ofprimarywaterstresscorrosion cracking(PWSCC)atTSPintersections. | |||
II | IfPWSCCisfoundatthesupportplateintersections itwillbereportedtotheNRCstaffpriortostartup.2)Theuseofsupporting datasetsforcalculation ofburstprobability andestimation ofprimary-to-secondary leakageduringapostulated mainSLBforeachoutagewillbebasedonthemostcurrent,NRC-approved industrydatabase.Thelatestindustrydatabasewastransmitted totheNRCunderBeaverValleyPowerStation', | ||
hh0 | Unit1,March27,1996,lettertransmitting supplemental information insupportofarequested T/Schange,foravoltage-based SGtuberepaircriteria, originally proposedintheirletterdatedDecember7,1995.Thatdatabasewasusedinthepreparation ofthissubmittal. | ||
3)Mainsteamlineburstprobability andleakagecalculations willbeperformed following theguidanceofGL95-05,Section2,"TubeIntegrity Evaluation." | |||
I | Calculations performed insupportofthevoltage-based repaircriteriawillfollowthemethodology described inWCAP-14277, "SteamLineBreakLeakRateandTubeBurstProbability AnalysisMethodsforOutsideDiameterStressCorrosion CrackingatTubeSupportPlateIntersections,'" | ||
datedJanuary1995.Thecalculations, usingtheas-foundvoltagedistribution, willbeperformed priortoreturning theSGstoservice.Theprojected EOCvoltagedistribution resultswillbereportedinthe90dayreport.4)Inspection scope,dataacquisition, anddataanalysiswillbeperformed following theguidanceofGL95-05,Section3,"Inspection Criteria" andreferenced AppendixA,'DEDataAcquisition andAnalysisGuidelines." | |||
AnMRPCinspection willbedoneonallindications exceeding 2volts.AnMRPCinspection willalsobedoneonallintersections wherecoppersignals,largemixedresiduals, ordentslargerthan5voltsinterfere withdetection offlaws. | |||
II Attachment 1toAEP:NRC:1166AA Page3Probewearinspections andre-inspections willbeperformed usingthefolloOing guidelines: | |||
Ifanyofthelastprobewearstandardsignalamplitudes, priortoprobereplacement, exceedthe215Xlimitbyavalueof"XX,"thenanyindications measuredsincethelastacceptable probewearmeasurement thatarewithin"XX"oftheplugginglimitwillbereinspected withthenewprobe.Forexample,ifanyofthelastprobewearsignalamplitudes priortoprobereplacement were17Xaboveorbelowtheinitialamplitude, thentheindications thatarewithin2X(17X-15X) oftheplugginglimitmustbereinspected withthenewprobe.Alternatively, thevoltagecriterion maybeloweredtocompensate fortheexcessvariation; forthecaseabove,amplitudes | |||
)0.98timesthevoltagecriterion couldbesubjecttorepair.5)Tuberemovalandexamination willbeperformed basedontheguidancecontained inGL95-05,Section4,"TubeRemovalandExamination/Testing." | |||
Plansaretopullatubespecimenwithatleasttwointersections duringthe1997refueling outage.6)Application ofGL95-05,Section5,"Operational LeakageRequirements," | |||
wi,llbecontinued. | |||
TheSGtubeleakagelimitof150gallonsperdaythrougheachSGwillbemaintained aspreviously approvedbytheNRCforourpresentfuelcycle.CookNuclearPlantleakagemonitoring methodsprovidetimelyleakdetection, | |||
: trending, andresponsetorapidlyincreasing leaks.7)GL95-05,Section6,"Reporting Requirements," | |||
willbeimplemented. | |||
Asstatedpreviously forSection2,thecalculation ofleakageandburstprobability requiredpriortoreturning theSGstoservicewillbeperformed usingoftheas-foundEOCvoltagedistribution. | |||
hh0 Attachment 1toAEP:NRC:1166AA Page4III.AEPCOMMENTSTOGL95-05ANDASSOCIATED IMPACTTOAEPLICENSEAMENDMENT REUESTFORSGPLUGGINGCRITERIA1)GL95-05,Sectionl.b:Analysesperformed byWestinghouse haveshownthatnotubesintheCookNuclearPlantUnit1SGswouldbesubjecttocollapseduringalossofcoolantaccident(LOCA)plussafeshutdownearthquake (SSE)eventsTherefore, notubesareexcludedbasedonthiscriteria. | |||
Series51SGs,designedbyWestinghouse, donothaveflowdistribution baffleplates;therefore, Sectionl.b.5isnotapplicable. | |||
2)GL95-05,Section3.c.3:Therequirement toreinspect alltubespriortothelastprobechangeout ifthewearmeasurement exceeds15/isunnecessary. | |||
Reinspection ofindications necessitated byout-of-specification probewearwillbeconducted according toitem4ofpage2ofthisattachment. | |||
IV.10CFR5092EVALUATION BACKGROUND CookNuclearPlantUnit1T/SAmendment 200permitted theimplementation ofa2voltSGtubepluggingcriteria. | |||
Thatlicenseamendment, applicable onlyforthecurrentoperating cycle(cycle15),requirestherepairofflaw-like bobbinindications above2volts.Weareproposing useofasimilar2voltrepaircriterion withoutthecycle-specific limitation. | |||
TheproposedpluggingcriteriaprogramfortheCookNuclearPlantUnit1SGsfollowstheguidanceandgeneralintentofGL95-05tomaintaintubestructural andleakageintegrity. | |||
DESCRIPTION OFTHEPLUGGINGCRITERIAREQUESTAsrequiredby10CFR50.91(a)(1),ananalysisisprovidedtodemonstrate thattheproposedlicenseamendment toimplement apluggingcriteriafortheTSPelevation OutsideDiameterStressCorrosion Cracking(ODSCC)occurring intheCookNuclearPlantUnit1SGsinvolvesanosignificant hazardsconsideration. | |||
Thepluggingcriteriautilizescorrelations betweeneddycurrentbobbincoilprobesignalamplitude (voltage) andtubeburstandleakagecapability. | |||
Thepluggingcriterion isbasedontestingoflaboratory inducedODSCCspecimens andonextensive examination of Attachment 1toAEP:NRC:1166AA Page5pulledtubesfromoperating SGs(industry wide--including threetubespulledin1992'epresenting nineintersections fromCookNuclearPlantUnit1).Consistent withGL95-05,thepluggingcriteriaprogramforCookNuclearPlantUnit1willincludethefollowing elementsaslistedunder"1.OverviewoftheVoltageRepairLimitApproach," | |||
page3ofGL95-05.Performanenhancedinspection oftubes,particularly attheTSPintersections. | |||
A100Kbobbincoilinspection ofhotlegTSPintersections andcoldlegintersections, downtothelowestcoldlegsupportplatewithknownODSCCindications, willbeperformed. | |||
Allflawindications withbobbinvoltagesgreaterthan2voltswillbeinspected byMRPC.UtilizeNondestructive Examination (NDE)dataacquisition andanalysisprocedures thatareconsistent withthemethodology usedtodevelopthevoltage-based repairlimits.Theinspection scope,dataaquisistion, anddata-analysiswillbeperformed usingtheguidanceofSection3oftheGL.Repairtubesthatexceedthevoltagelimits.Flaw-like signalsadjacenttotheTSP,withbobbinvoltageslessthanorequalto2volts,willbeallowedtoremaininservice.Flaw-like indications adjacenttotheTSP,withabobbinvoltageofgreaterthan2voltsbutlessthanorequaltouppervoltagerepairlimit,mayremaininserviceifMRPCinspection doesnotdetectaflaw.Flawindications withavoltageofgreaterthantheuppervoltagerepairlimitwillberepaired. | |||
Determine theBeginning ofCycle(BOC)voltagedistribution. | |||
Beginning ofCyclevoltagedistribution willbeestablished fromtheactualtubeinspections tobeperformed andwillbeestablished usingcurrentprogrammethodology. | |||
ProjecttheEOCdistribution. | |||
AnEOCvoltagedistribution willbeestablished basedontheEOCeddycurrenttestdata.EOCvoltagedistribution willbeprojected usingMonteCarlotechniques asdescribed inWCAP-hI1 Attachment 1toAEP:NRC:1166AA Page614277andwillincludeallowance foreddycurrentuncertainty asdefinedinGL95-05andaconservative voltagegrowthrateallowance. | |||
Fortheprojected EOCvoltagedistribution, calculate boththeprimary-to-secondary leakageunderpostulated accidentconditions andtheconditional tubeburstprobabili ty.Asanalternative, theactualmeasuredEOCvoltagedistribution canbeusedwhenitisimpractical tocompletethe,projected EOCcalculation priortoreturning theSGstoserviceforthepurposeofdetermining whetherthereporting criteriainGI95-05Sections6.a.land6.a.3apply.Steamlinebreakleakagewillbecalculated, asdescribed inWCAP-14277,basedontheEOCprojected voltagedistribution. | |||
Projected leakagemustremainbelow8.4gpminthefaultedloopforpermissible offsitedoseestimates toremainacceptable within10Xofthe10CFR100guidelines. | |||
The8.4gpmleakageforoffsitedoseestimates issmallerthantheleakagenumbercalculated foracceptable controlroomdoseperGeneralDesignCriteria(GDC)19.Therefore, theoffsitedoseismorelimiting. | |||
Conditional tubeburstprobability willbecalculated according tothemethodology described inWCAP-14277. | |||
Consistent withGL95-05,ifburstprobability isfoundtobegreaterthan1x10~theNRCwillbeconsulted. | |||
Asprescribed inGL95-05,anevaluation ofprimary-to-secondary leakage(andsubsequently offsitedose)isrequiredforallplantsimplementing thepluggingcriteria. | |||
Allbobbincoilindications areincludedintheSLBleakageanalyses, alongwithconsideration oftheprobability ofdetection. | |||
Iftheprojected leakageexceeds8.4gpminthefaultedloopduringapostulated SLBevent,thenumberofindications towhichthepluggingcriteriaareappliedisreduced,throughtuberepair,untiltheprimary-to-secondary leakagelimitsaresatisfied. | |||
EVALUATION TubeDegradation Characterization Ingeneral,thedegradation morphology occurring attheTSPintersections atplantsintheU.S.canbedescribed asaxiallyorientedODSCC.Thedegradation morphology atCookNuclearPlantUnit1isentirelycompatible withtheoverallindustrydatabase. | |||
Attachment 1toAEP:NRC:1166AA Page7SteamGenerator TubeIntegrity Inthedevelopment ofapluggingcriteriaforCookNuclearPlantUnit1,Regulatory Guide(RG)1.121,"BasesforPluggingDegradedPWRSteamGenerator Tubes"andRGl.'83,"In-service Inspection ofPWRSteamGenerator Tubes"areusedasthebasesfordetermining thatSGtubeintegrity ismaintained withinacceptable limits.Regulatory Guide1.121describes amethodacceptable totheNRCstaffformeetingGDC14,15,31,and32byreducingtheprobability andconsequences ofSGtuberupturebydetermining thelimitingsafeconditions oftubewalldegradation beyondwhichtubeswithunacceptable | |||
: cracking, asestablished byin-service inspection, shouldberemovedfromservicebyplugging. | |||
Thisregulatory guideusessafetyfactorsonloadsfortubeburststhatareconsistent withtherequirements ofSectionIIIoftheASMECode.FortheTSPelevation degradation occurring intheCookNuclearPlantUnit1SGs,tubeburstcriteriaareinherently satisfied duringnormaloperating conditions bythepresenceoftheTSP.ThepresenceoftheTSPenhancestheintegrity ofthedegradedtubesinthatregionbyprecluding tubedeformation beyondthediameterofthedrilledhole,thusprecluding tubeburst.Conservatively, nocreditistakeninthedevelopment ofthepluggingcriteriaforthepresenceoftheTSPduringaccidentconditions. | |||
Basedontheexistingdatabasefor7/8inchtubing,bursttestingindicates thatthesafetyrequirements fortubeburstmarginsduringaccidentcondition loadingcanbesatisfied withEOCbobbincoilsignalamplitudes lessthan8.8volts,regardless ofthedepthoftubewallpenetration ofthecracking. | |||
Uponimplementation oftheproposedpluggingcriteriaprogram,tubeleakageconsiderations mustalsobeaddressed. | |||
Itmustbedetermined thatthecrackswillnotleakexcessively duri~gallplantconditions. | |||
Forthe2voltinterimtubepluggingcriteriadeveloped fortheCookNuclearPlantUnit1SGtubes,noleakageisanticipated duringnormaloperating conditions evenwiththepresenceofpotential throughwall cracks.Noprimary-to-secondary leakageattheTSPhasbeendetectedinU.S.plants.Relativetotheexpectedleakageduringaccidentcondition loading,thelimitingeventwithrespecttodifferential pressureexperienced acrosstheSGtubesisapostulated SLBevent.For7/8inchtubing,pulledtubedatasupportsnoleakageupto2.81voltsandlowprobability ofleakagebetween2.81and6.0volts,forbothpulledtubesandmodelboilerspecimens, attheboundingSLBpressuredifferential of2560psi.Steamlinebreakprimary-to-secondary leakagewillbecalculated asprescribed inGL95-05andWCAP14277,usingprojected EOCeddycurrentdata.Thiscalculated leakagemustbeshowntobelessthan8.4gpminthefaultedloop. | |||
I Attachment 1toAEP:NRC:1166AA Page8Additional Considerations | |||
~*Theproposedamendment wouldprecludeoccupational radiation exposurethatwouldotherwise beincurredbypersonnel involvedintubepluggingorrepairoperations. | |||
Byreducingnon-essential tubeplugging, theproposedamendment wouldminimizethelossofmargininthereactorcoolantflow,throughtheSGs,usedinLOCAanalyses. | |||
Theproposedamendment wouldavoidlossofmargininreactorcoolantsystemflowand,therefore, assistinmaintaining minimumflowratesinexcessofthatrequiredforoperation atfullpower.Reduction intheamountoftuberepairrequiredcanreducethelengthofplantoutagesandreducethetimethattheSGsareopentothecontainment environment duringanoutage.A100Xeddycurrentbobbincoilprobeinspection associated withimplemen'tation ofthepluggingcriteriaprogramwillhelptoidentifynewareasofconcernwhichmayarise,byproviding alevelofin-service inspection whichisfarinexcessoftheT/Srequirements utilizing the40Xdepth-based plugginglimitforacceptable tubewalldegradation. | |||
SIGNIFICANT HAZARDSANALYSISInaccordance withthethreefactortestof10CFR50.92(c), | |||
implementation oftheproposedlicenseamendment isanalyzedusingthefollowing standards andfoundnotto:1)involveasignificant increaseintheprobability orconsequences ofanaccidentpreviously evaluated; 2)createthepossibility ofanewordifferent kindofaccidentfromanyaccidentpreviously evaluated; or3)involveasignificant reduction inmarginofsafety.Conformance oftheproposedamendment tothestandards foradetermination ofnosignificant hazardsasdefinedin10CFR50.92(threefactortest)isshowninthefollowing paragraphs: | |||
1)Operation ofCookNuclearPlaneUnit1,inaccordance withtheproposedlicenseamendment, doesnotinvolveasignificant increaseintheprobability orconsequences ofanaccidentpreviously evaluated. | |||
Testingofmodelboilerspecimens forfreespantubing(noTSPrestraint) atroomtemperature conditions showburstpressures inexcessof5000psiforindications ofouterdiameterstresscorrosion crackingwithvoltagemeasurements ashighas19volts.Bursttestingperformed onpulledtubesfromCookNuclearPlantUnit1withuptoa2.02voltindication showsmeasuredburstpressureinexcessof10,000psiatroomtemperature. | |||
Bursttestingperformed onpulledtubesfromotherplantsshowburstpressures inexcessof5,300psiatroomtemperatures. | |||
Correcting fortheeffectsoftemperature onmaterialproperties andminimumstrengthlevels(astheburst | |||
Attachment 1toAEP:NRC:1166AA Page9testingwasdoneatroomtemperature), | |||
tubeburstresistance significantly exceedsthesafetyfactorrequirements ofRG1.121.Asstatedearlier,tubeburstcriteriaareinherently satisfied duringnormaloperating conditions duetotheproximity oftheTSP.Testdataindicates thattubeburstcannotoccurwithintheTSP,evenfortubeswhichhave100Xthroughwall electric-discharge machinednotches0.75inchlong,providedtheTSPisadjacenttothenotchedarea,Sincetube-to-tube supportplateproximity precludes tubeburstduringnormaloperating conditions, itfollowsthatuseoftheproposedpluggingcriteriamust,therefore, retaintubeintegrity characteristics whichmaintaintheRG1.121marginofsafetyof1.43timestheboundingfaultedcondition (steamlinebreak)pressuredifferential. | |||
Duringapostulated mainSLB,theTSPhasthepotential todeflectduringblowdown, therebyuncovering theintersection. | |||
Basedontheexistingdatabase,theRG1.121criterion requiring maintenance ofasafetyfactorof1.43timestheSLBpressuredifferential ontubeburstissatisfied by7/8inchdiametertubingwithbobbincoilindications withsignalamplitudes lessthanV><,regardless oftheindicated depthmeasurement. | |||
A2voltpluggingcriteriacomparesfavorably withthecurrentV><(8.8volt)structural limit,considering thepreviously calculated growthratesforODSCCwithinCookNuclearPlantUnit1SGs.Considering avoltagegrowthcomponent of0.8volts(40Xvoltagegrowthbasedon2voltsBOC)andanondestructive examination uncertainty of0.40volts(20Xvoltageuncertainty basedon2voltsBOC),whenaddedtotheBOCpluggingcriteriaof2volts,resultsinaboundingEOCvoltageofapproximately 3.2voltsforacycleoperation. | |||
A5.6voltsafetymarginexists(8.8-3.2voltEOC-5.6voltmargin).Forthevoltage/burst correlation, theEOCstructural limitissupported byavoltageof8.8volts.UsingthisVz<of8.8volts,aBOCmaximumallowable repairlimitcanbeestablished usingtheguidanceofRG1.121.TheBOCmaximumallowable repairlimitshouldnotpermitasignificant numberofEOCindications toexceedtheVz<andshouldassurethatacceptable tubeburstprobabilities areattained. | |||
ByaddingNDEuncertainty allowances andanallowance forcrackgrowthtotherepairlimit,thestructural limitcanbevalidated. | |||
Thepreviouspluggingcriteriasubmittal established theconservative NDEuncertainty limit(V<><)of20XoftheBOCrepair-limit.Forconsistency, a40Xvoltagegrowthallowance (V<<)totheBOCrepairlimitisalsoincluded. | |||
Thisallowance isextremely conservative forCookNuclear | |||
Attachment 1toAEP:NRC:1166AA Page10PlantUnit1.Therefore, themaximumallowable uppervoltagerepairlimitV<<<forBOC,basedontheV><of8.8volts,canberepresented bytheexpression: | |||
VURL+(VADExVURL)+(VMxVuRL)=8.8volts,or,themaximumallowable BOCrepairlimitcanbeexpressed as,Vz<<=8.8voltstructural limit/1.6 | |||
=5.5volts.Thisstructural repairlimitsupportsthisapplication forpluggingcriteriaimplementation torepairbobbinindications greaterthan2voltsbasedonRPCconfirmation oftheindication. | |||
Conservatively, anupperlimitof5.5voltswillbeusedtorepairbobbincoilindications whichareabove2voltsbutdonothaveconfirming RPCcalls.Relativetotheexpectedleakageduringaccidentcondition | |||
: loadings, ithasbeenpreviously established thatapostulated mainSLBoutsideofcontainment, butupstreamofthemainsteamisolation valve,represents themostlimitingradiological condition relativetothepluggingcriteria. | |||
Insupportofimplementation ofthepluggingcriteria, itwillbedetermined whetherthedistribution ofcrackindications attheTSPintersections attheEOCareprojected tobesuchthatprimary-to-secondary leakagewouldresultinsiteboundarydoseswithinasmallfractionofthe10CFR100guidelines. | |||
Aseparatecalculation hasdetermined thisallowable SLBleakagelimittobe8.4gpm.AlthoughnotrequiredbytheCookNuclearPlantdesignbasis,thiscalculation usestherecommended Iodine-131 transient spikingvaluesconsistent withNUREG-0800, andtheT/Sreactorcoolantsystemactivitylimi,tof1microcuriepergramdoseequivalent Iodine-131. | |||
Controlroomdosecalculations werealsoperformed andfoundtobelesslimitingthantheoffsitedosecalculation leakrate. | |||
Therefore, themoreconservative offsitedoseleakrateisused.Theprojected SLBleakageratecalculation methodology prescribed inGL95-05andWCAP14277willbeusedtocalculate EOCleakage,basedonactualEOCdistributions andEOCprojected distributions. | |||
Duetotherelatively lowvoltagegrowthratesatCookNuclearPlantUnit1andtherelatively smallnumberofindications affectedbythepluggingcriteria, SLBleakageprediction perGL95-05isexpectedtobesignificantly lessthanthepermissible level.of8.4gpminthefaultedloop.Theinclusion ofallintersections intheleakagemodel,alongwithapplication ofaprobability ofdetection of0.6, | |||
Attachment 1toAEP:NRC:1166AA Page11willresultinextremely conservative leakageestimations. | |||
Closeexaminat'ion oftheavailable datashowsthatindications oflessthan2.8voltswillnotbeexpectedtoleakduringSLBconditions. | |||
Theproposedamendment doesnotresultinanyincreaseintheprobability orconsequences ofanaccidentpreviously evaluated withintheCookNuclearPlantUnit1FinalSafetyAnalysisReport(FSAR).2)Theproposedlicenseamendment doesnotcreatethepossibility ofanewordifferent kindofaccidentfromanyaccidentpreviously evaluated. | |||
Implementation oftheproposedSGtubepluggingcriteriadoesnotintroduce anysignificant changestotheplantdesignbasis.Useofthecriteriadoesnotprovideamechanism whichcouldresultinanaccidentoutsideoftheregionoftheTSPelevations. | |||
Neitherasinglenoramultipletuberuptureeventwould,underanyplantconditions, beexpectedinaSGinwhichthepluggingcriteriahasbeenapplied.Specifically, wewillcontinuetoimplement amaximumleakageratelimitof150gpd(0.1gpm)perSGtohelpprecludethepotential forexcessive leakageduringallplantconditions. | |||
TheT/Slimitsimposedonprimary-to-secondary leakageatoperating conditions areamaximumof0.4gpm(600gpd)forallSGswithamaximumof150gpdallowedforanyoneSG~TheRG1.121criteriaforestablishing operational leakageratelimitsthatrequireplantshutdownarebaseduponleak-before-break (LBB)considerations todetectafreespancrackbeforepotential tuberuptureduringfaultedplantconditions. | |||
The150gpdlimitshouldprovideforleakagedetection andplantshutdownintheeventoftheoccurrence ofanunexpected singlecrackresulting inleakagethatisassociated withthelongestpermissible cracklength.Regulatory Guide1.121acceptance criteriaforestablishing operating leakagelimitsarebasedonLBBconsiderations suchthatplantshutdownisinitiated iftheleakageassociated withthelongestpermissible crack,isexceeded. | |||
Thelongestpermissible crackisthelengththatprovidesafactorofsafetyof1.43againstburstingatfaultedconditions maximumpressuredifferential. | |||
Avoltageamplitude of8.8voltsfortypicalODSCCcorresponds tomeetingthistubeburstrequirement atalower95/prediction limitontheburstcorrelation coupledwith95/95lowertolerance limitmaterialproperties. | |||
Alternate crackmorphologies cancorrespond to | |||
Attachment 1toAEP:NRC:1166AA Page128.8voltssothatauniquecracklengthisnotdefinedbytheburstpressure"versusvoltagecorrelation. | |||
Consequently, typicalburstpressureversusthrough-wall cracklengthcorrelations wereusedtodefinethe"longestpermissible crack"forevaluating operating leakagelimits.Consistent withthecycle13,14and15licenseamendment requestsforpluggingcriteria, andSection5ofEnclosure 1oftheGL,operational leakagelimitswillremainat150gpd.perSG.AxialcracksleakingatthislevelareexpectedtoprovideLBBprotection atboththeSLBpressuredifferential of2560psiand,whilenotpartofanyestablished LBBmethodology, LBBprotection willalsobeprovidedatavalueof1.43timestheSLBpressuredifferential. | |||
Thus,the150gpdlimitprovidesforplantshutdownpriortoreachingcriticalcracklengthsforSLBconditions. | |||
Additionally, thisLBBevaluation assumesthattheentirecreviceareaisuncovered duringblowdown. | |||
Partialuncoverywillprovidebenefittotheburstcapacityoftheintersection. | |||
3)Theproposedlicenseamendment doesnotinvolveasignificant reduction inmarginofsafety.Theuseofthevoltage-based bobbinprobeinterimTSPelevation pluggingcriteriaatCookNuclearPlantUnit1isdemonstrated tomaintainSGtubeintegrity commensurate withthecriteriaofRG1.121.Regulatory Guide1~121describes amethodacceptable totheNRCstaffformeetingGDC14,15,31,and32byreducingtheprobability ortheconsequences ofSGtuberupture.Thisisaccomplished bydetermining thelimitingconditions ofdegradation ofSGtubing,asestablished byin-service inspection, forwhichtubeswithunacceptable crackingshouldberemovedfromservice.Uponimplementation ofthecriteria, evenundertheworstcaseconditions, theoccurrence ofODSCCattheTSPelevations isnotexpectedtoleadtoaSGtuberuptureeventduringnormal,orfaultedplantconditions. | |||
Itwillbeconfirmed byanalysisandcalculation thatEOCdistribution ofcrackindications attheTSPelevations willresultinacceptable primary-to-secondary leakageduringallplantconditions andthatradiological consequences arenotadversely impacted. | |||
Inaddressing thecombinedeffectsofaLOCAandSSEontheSGcomponent (asrequiredbyGDC2),ithasbeendetermined thattubecollapsemayoccurintheSGsatsomeplants.Thepostulated tubecollapseresultsfromadeformation ofTSPsasaresultoflateralloadsatthewedgesupportsattheperiphery oftheplate.Thelateralloadsresultfromthe l | |||
Attachment 1toAEP:NRC:1166AA Page13combinedeffectsoftheLOCArarefaction waveandSSEloadings. | |||
Theresulting pressuredifferential onthedeformedtubesmaythencausesomeofthetubestocollapse. | |||
Therearetwoissuesassociated withapostulated SGtubecollapse. | |||
First,thecollapseofSGtubingreducestheRCSflowareathroughthetubes.Thereduction inflowareaincreases theresistance toflowofsteamfromthecoreduringaLOCAwhich,inturn,maypotentially increasepeakcladtemperature. | |||
Second,thereisapotential thatpartialthrough-wall cracksintubescouldprogresstothrough-wall cracksduringtubedeformation orcollapse. | |||
Consequently, sincetheLBBmethodology isapplicable totheCookNuclearPlantUnit1reactorcoolantlooppiping,theprobability ofbreaksintheprimarylooppipingissufficiently lowthattheyneednotbeconsidered inthestructural designoftheplant.ThelimitingLOCAeventbecomeseithertheaccumulator linebreakorthepressurizer surgelinebreak.LossofcoolantaccidentloadsfortheprimarypipebreakswereusedtoboundtheCookNuclearPlantUnit1smallerbreaks.TheresultsoftheanalysisusingthelargerbreakinputsshowthattheLOCAloadswerefoundtobeofinsufficient magnitude toresultinSGtubecollapseorsignificant deformation. | |||
Addressing RG1.83considerations, implementation of,thebobbincoilprobe,voltage-based interimtubepluggingcriteriaof2voltsissupplemented byenhancededdycurrent,inspection guidelines toprovideconsistency involtagenormalization, a100Xeddycurrentinspection samplesizeattheTSPelevations perT/S,andMRPCinspection requirements forthelargerindications leftin-service tocharacterize theprincipal degradation asODSCC.Asnotedpreviously, implementation oftheTSPelevation pluggingcriteriawilldecreasethenumberoftubeswhichmustberepaired. | |||
Theinstallation ofSGtubeplugsreducestheRCSflowmargin.Thus,implementation ofthepluggingcriteriawillmaintainthemarginofflowthatwouldotherwise bereducedintheeventofincreased tubeplugging. | |||
Basedontheabove,itisconcluded thattheproposedlicenseamendment requestdoesnotresultinasignificant reduction inmarginwithrespecttoplantsafetyasdefinedintheFSARoranyBasesoftheplantT/Ss. | |||
I,}} | I,}} |
Revision as of 07:17, 29 June 2018
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~
INFORMATION DISTRIBUTION SYSTEM(RIDS)ACCESSION NBR:9606260254 DOC.DATE:
96f06fl9NOTARIZED:
YESDOCKET:FACIL:50-315 DonaldC.CookNuclearPowerPlant,Unit1,IndianaM05000315AUTH.NAMEAUTHORAFFILIATION FITZPATR:.CK,E.
AmericanElectricPowerCo.,Inc.RECIP.NAME RECIPIENT AFFILIATION Document'ontrol Branch(Document ControlDesk)SUBJE!T:Application foramendtoLicenseDPR-58,addressing applicable requirements ofNRCGL95-05,"Voltage-Based C.RepairCriteriaforRepairofWestinghouse SGTubesAffectedby,OutsideDiameterStressCorrosion Cracking."
ADISTRIBUTION CODE:ADOIDCOPIESRECEIVED:LTR IENCL/SIZE:TITLE:ORSubmittal:
GeneralDistribution ENOTES:RECIPIENT IDCODE/NAME PD3-1LAHICKMAN,J INTERNAL,~IEl.
HE~NTE1%RR/DRCH~HICB NRR/DSSA/SRXB OGC/HDS2EXTERNAL:
NOACCOPIESLTTRENCL11111111111011RECIPIENT IDCODE/NAME PD3-1PDNRR/DE/EMCB NRR/DSSA/SPLB NUDOCS-ABSTRACT NRCPDRCOPIESLTTRENCL11111111D0NOTETOALL"RIDS"RECIPIENTS:
PLEASEHELPUSTOREDUCEWASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMOWFN5D-5(EXT.
415-2083)
TOELIMINATE YOURNAMEFROMDISTRIBUTION LISTSFORDOCUMENTS YOUDON'TNEED!ITOTALNUMBEROFCOPIESREQUIRED:
LTTR,12ENCLll eRf4>~4.1~'l4,C AmericanElectricP~1Riverside PlazaColumbus, OH4321523736142231000June19,1996AEP:NRC:1166AA DocketNos.:50-315U.S.NuclearRegulatory Commission ATTN:DocumentControlDeskWashington, D.C.20555Gentlemen:
DonaldC.CookNuclearPlantUnit1TECHNICAL SPECIFICATION CHANGESTOINCORPORATE 2VOLTSTEAMGENERATOR TUBESUPPORTPLATEREPAIRCRITERION Thisletteranditsattachments provideapplication foramendment tothetechnical specifications (T/Ss)ofDonaldC.CookNuclearPlantUnit1.Specifically, thisinformation addresses theapplicable requirements ofNRCGenericLetter(GL)95-05"Voltage-BasedRepairCriteriafortheRepairofWestinghouse SteamGenerator TubesAffectedbyOutsideDiameterStressCorrosion Cracking."
Attachment 1providesatechnical summaryoft:hespecificinspection practices andcalculation methodologies outlinedinGL95-05andthe10CFR50.92nosignificant hazardsevaluation.
Theevaluation andresultssupportcontinued useofthe2voltpluggingcriteriaasallowedbyGL95-05forfutureoperating cycles.Attachment 2containsexistingT/Spagesmarkedtoreflecttherequested changes.Attachment 3providestheproposedrevisedT/Spages.Webelievetheproposedchangeswillnotresultin(1)asignificant changeinthetypesofanyeffluentthatmaybereleasedoffsite,or(2)asignificant increaseinindividual orcumulative occupat.i.onal radiation exposure.
9606260254';.9606 19'DRADOCK.050003i5 P.PDR U.S.NuclearRegulatory Commission Page2AEP:NRC:1166AA TheseproposedchangeshavebeenreviewedbythePlantNuclearSafetyReviewCommittee andtheNuclearSafetyandDesignReviewCommittee.
Incompliance withtherequirements of10CFR50.91(b)(1),
copiesofthisletteranditsattachments havebeentransmitted totheMichiganPublicServiceCommission andtotheMichiganDepartment ofPublicHealth.Sincerely, VicePresident SWORNTOANDSUBSCRIBED BEFOREMETHIS~~~4DAYOF1996teryPublicllgAttachments cc:A.A.BlindG.CharnoffH.J.MillerNFEMSectionChiefNRCResidentInspector
-BridgmanJ.R.Padgett U.S.NuclearRegulatory Commission Page3AEP:NRC:1166AA bc: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/attachment PRONET-w/attachment DC-N-6015.1 J'
AmericanElectric1Riverside PlazaColumbus, OH4321523736142231000ANERlCAMELECfRICPOWERJune19,1996AEP:NRC:1166AA DocketNos~:50-315U.S.NuclearRegulatory Commission ATTN:DocumentControlDeskWashington, D.C.20555Gentlemen:
DonaldC.CookNuclearPlantUnit1TECHNICAL SPECIFICATION CHANGESTOINCORPORATE 2VOLTSTEAMGENERATOR TUBESUPPORTPLATEREPAIRCRITERION Thisletteranditsattachments provideapplication foramendment tothetechnical specifications (T/Ss)ofDonaldC.CookNuclearPlantUnit1.Specifically, thisinformation addresses theapplicable requirements ofNRCGenericLetter(GL)95-05"Voltage-BasedRepairCriteriafortheRepairofWestinghouse SteamGenerator TubesAffectedbyOutsideDiameterStressCorrosion Cracking."
Attachment 1providesatechnical summaryofthespecificinspection practices andcalculation methodologies outlinedinGL95-05andthe10CFR50.92nosignificant hazardsevaluation.
Theevaluation andresultssupportcontinued useofthe2voltpluggingcriteriaasallowedbyGL95-05forfutureoperating cycles.Attachment 2containsexistingT/Spagesmarkedtoreflecttherequested changes.Attachment 3providestheproposedrevisedT/Spages.Webelievetheproposedchangeswillnotresultin(1)asignificant changeinthetypesofanyeffluentthatmaybereleasedoffsite,or(2)asignificant increaseinindividual orcumulative occupational radiation exposure.
U.S.NuclearRegulatory Commission Page2AEP:NRC:1166AA TheseproposedchangeshavebeenreviewedbythePlantNuclearSafetyReviewCommittee andtheNuclearSafetyandDesignReviewCommittee.
Incompliance withtherequirements of10CFR50.91(b)(l),
copiesofthisletteranditsattachments havebeentransmitted totheMichiganPublicServiceCommission andtotheMichiganDepartment ofPublicHealth.Sincerely, PgM.~,xi)
E.E.Fitzpatrick VicePresident SWOP'OANDSUBSCRIBED BEFOREMETHIS~cP4'AYOF1996.CotaryPublicw"llgAttachments cc:A.A.BlindG.CharnoffH.J~MillerNFEMSectionChiefNRCResidentInspector
-BridgmanJ.R.Padgett U.S.NuclearRegulatory Commission Page3AEP:NRC:1166AA bc: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/attachment PRONET-w/attachment DC-N-6015.1 ATTACHMENT 1TOAEP:NRC:1166AA DESCRIPTION OFCHANGESTOTHEDONALDC.COOKNUCLEARPLANTUNIT1TECHNICAL SPECIFICATIONS 10CFR50.92EVALUATION Attachment 1toAEP:NRC:1166AA Page1INTRODUCTION Thisamendment requestproposesachangetoCookNuclearPlantUnit1steamgenerators (SG)T/Ss4.4.5.2,4.4.5.4,4.4'.5,3.4.6.2andBases3/4.4.5and3/4.4.6.2 toallowuseofGL95-05voltage-based SGtubesupportplate(TSP)pluggingcriteria.
ThechangeallowsSGtubeswithbobbincoileddycurrentindications lessthanorequalto2voltsatTSPintersections toremaininservice,regardless oftheapparentdepthoftubewallpenetration if,asaresult,theprojected end-of-cycle (EOC)distribution ofcrackindications isshowntoresultinprimary-to-secondary leakagelessthan8.4gpminthefaultedloopduringapostulated steamlinebreak(SLB)event.Indications greaterthan2voltsbutlessthanorequaltotheuppervoltagerepairlimit(VU<L)mayremaininserviceifamotorized rotatingpancakecoil(MRPC)probeinspection doesnotdetectdegradation.
TheVUgLwillbedetermined eachoutageusingthemostrecent,NRC-approved industrytubeburstdatabasetodetermine thevoltagecorresponding tothetubestructural limit(VSL).Thisamendment wouldreducethenumberofSGtubespluggedduetoindications atsupportplateintersections.
ReducingthenumberofpluggedtubesprovidesALARAbenefitsandmaintains reactorcoolantsystem(RCS)flowmargin.Assessment reportsaddressing theeffectiveness ofthevoltage-based pluggingcriteriamethodology aredescribed inWCAP-13187, Revision0,whichwascompleted following fuelcycles13and14.Thisinformation wasreportedinsubmittal documents AEP:NRC:1166J andAEP:NRC:1166AC.
Thereportsconcluded thatthevoltagedistribution foundbyinspection atEOC13andEOC14,in1994and1995,respectively, wereingoodagreement withtheprojections'he voltagegrowthratescontinuetobeverysmall.Noin-service tubeswerefoundforwhichthebobbincoilvoltageexceededthe2voltpluggingcriteriarepairlimitatEOC13orEOC14.Considering theresultsoftheaforementioned reports,continued useofthe2voltpluggingcriteriaisjustified.
Similarassessment andprojection reportsbasedonGL95-05reporting requirements willbepreparedateachEOC.
Attachment 1toAEP:NRC:1166AA Page2APPLICATION OFGL95-05TOTHECOOKNUCLEARPLANTUNIT1SG'ICENSE AMENDMENT TheCookNuclearPlantUnit1,2voltpluggingcriteriawillbeimplemented pertheguidanceofGL95-05alongwiththelatestindustrydatafortubeburstandleakage.NRCGL95-05willbefactoredintotheCookNuclearPlantUnit1pluggingcriteriaasfollows:Analystswillbebriefedregarding thepossibility ofprimarywaterstresscorrosion cracking(PWSCC)atTSPintersections.
IfPWSCCisfoundatthesupportplateintersections itwillbereportedtotheNRCstaffpriortostartup.2)Theuseofsupporting datasetsforcalculation ofburstprobability andestimation ofprimary-to-secondary leakageduringapostulated mainSLBforeachoutagewillbebasedonthemostcurrent,NRC-approved industrydatabase.Thelatestindustrydatabasewastransmitted totheNRCunderBeaverValleyPowerStation',
Unit1,March27,1996,lettertransmitting supplemental information insupportofarequested T/Schange,foravoltage-based SGtuberepaircriteria, originally proposedintheirletterdatedDecember7,1995.Thatdatabasewasusedinthepreparation ofthissubmittal.
3)Mainsteamlineburstprobability andleakagecalculations willbeperformed following theguidanceofGL95-05,Section2,"TubeIntegrity Evaluation."
Calculations performed insupportofthevoltage-based repaircriteriawillfollowthemethodology described inWCAP-14277, "SteamLineBreakLeakRateandTubeBurstProbability AnalysisMethodsforOutsideDiameterStressCorrosion CrackingatTubeSupportPlateIntersections,'"
datedJanuary1995.Thecalculations, usingtheas-foundvoltagedistribution, willbeperformed priortoreturning theSGstoservice.Theprojected EOCvoltagedistribution resultswillbereportedinthe90dayreport.4)Inspection scope,dataacquisition, anddataanalysiswillbeperformed following theguidanceofGL95-05,Section3,"Inspection Criteria" andreferenced AppendixA,'DEDataAcquisition andAnalysisGuidelines."
AnMRPCinspection willbedoneonallindications exceeding 2volts.AnMRPCinspection willalsobedoneonallintersections wherecoppersignals,largemixedresiduals, ordentslargerthan5voltsinterfere withdetection offlaws.
II Attachment 1toAEP:NRC:1166AA Page3Probewearinspections andre-inspections willbeperformed usingthefolloOing guidelines:
Ifanyofthelastprobewearstandardsignalamplitudes, priortoprobereplacement, exceedthe215Xlimitbyavalueof"XX,"thenanyindications measuredsincethelastacceptable probewearmeasurement thatarewithin"XX"oftheplugginglimitwillbereinspected withthenewprobe.Forexample,ifanyofthelastprobewearsignalamplitudes priortoprobereplacement were17Xaboveorbelowtheinitialamplitude, thentheindications thatarewithin2X(17X-15X) oftheplugginglimitmustbereinspected withthenewprobe.Alternatively, thevoltagecriterion maybeloweredtocompensate fortheexcessvariation; forthecaseabove,amplitudes
)0.98timesthevoltagecriterion couldbesubjecttorepair.5)Tuberemovalandexamination willbeperformed basedontheguidancecontained inGL95-05,Section4,"TubeRemovalandExamination/Testing."
Plansaretopullatubespecimenwithatleasttwointersections duringthe1997refueling outage.6)Application ofGL95-05,Section5,"Operational LeakageRequirements,"
wi,llbecontinued.
TheSGtubeleakagelimitof150gallonsperdaythrougheachSGwillbemaintained aspreviously approvedbytheNRCforourpresentfuelcycle.CookNuclearPlantleakagemonitoring methodsprovidetimelyleakdetection,
- trending, andresponsetorapidlyincreasing leaks.7)GL95-05,Section6,"Reporting Requirements,"
willbeimplemented.
Asstatedpreviously forSection2,thecalculation ofleakageandburstprobability requiredpriortoreturning theSGstoservicewillbeperformed usingoftheas-foundEOCvoltagedistribution.
hh0 Attachment 1toAEP:NRC:1166AA Page4III.AEPCOMMENTSTOGL95-05ANDASSOCIATED IMPACTTOAEPLICENSEAMENDMENT REUESTFORSGPLUGGINGCRITERIA1)GL95-05,Sectionl.b:Analysesperformed byWestinghouse haveshownthatnotubesintheCookNuclearPlantUnit1SGswouldbesubjecttocollapseduringalossofcoolantaccident(LOCA)plussafeshutdownearthquake (SSE)eventsTherefore, notubesareexcludedbasedonthiscriteria.
Series51SGs,designedbyWestinghouse, donothaveflowdistribution baffleplates;therefore, Sectionl.b.5isnotapplicable.
2)GL95-05,Section3.c.3:Therequirement toreinspect alltubespriortothelastprobechangeout ifthewearmeasurement exceeds15/isunnecessary.
Reinspection ofindications necessitated byout-of-specification probewearwillbeconducted according toitem4ofpage2ofthisattachment.
IV.10CFR5092EVALUATION BACKGROUND CookNuclearPlantUnit1T/SAmendment 200permitted theimplementation ofa2voltSGtubepluggingcriteria.
Thatlicenseamendment, applicable onlyforthecurrentoperating cycle(cycle15),requirestherepairofflaw-like bobbinindications above2volts.Weareproposing useofasimilar2voltrepaircriterion withoutthecycle-specific limitation.
TheproposedpluggingcriteriaprogramfortheCookNuclearPlantUnit1SGsfollowstheguidanceandgeneralintentofGL95-05tomaintaintubestructural andleakageintegrity.
DESCRIPTION OFTHEPLUGGINGCRITERIAREQUESTAsrequiredby10CFR50.91(a)(1),ananalysisisprovidedtodemonstrate thattheproposedlicenseamendment toimplement apluggingcriteriafortheTSPelevation OutsideDiameterStressCorrosion Cracking(ODSCC)occurring intheCookNuclearPlantUnit1SGsinvolvesanosignificant hazardsconsideration.
Thepluggingcriteriautilizescorrelations betweeneddycurrentbobbincoilprobesignalamplitude (voltage) andtubeburstandleakagecapability.
Thepluggingcriterion isbasedontestingoflaboratory inducedODSCCspecimens andonextensive examination of Attachment 1toAEP:NRC:1166AA Page5pulledtubesfromoperating SGs(industry wide--including threetubespulledin1992'epresenting nineintersections fromCookNuclearPlantUnit1).Consistent withGL95-05,thepluggingcriteriaprogramforCookNuclearPlantUnit1willincludethefollowing elementsaslistedunder"1.OverviewoftheVoltageRepairLimitApproach,"
page3ofGL95-05.Performanenhancedinspection oftubes,particularly attheTSPintersections.
A100Kbobbincoilinspection ofhotlegTSPintersections andcoldlegintersections, downtothelowestcoldlegsupportplatewithknownODSCCindications, willbeperformed.
Allflawindications withbobbinvoltagesgreaterthan2voltswillbeinspected byMRPC.UtilizeNondestructive Examination (NDE)dataacquisition andanalysisprocedures thatareconsistent withthemethodology usedtodevelopthevoltage-based repairlimits.Theinspection scope,dataaquisistion, anddata-analysiswillbeperformed usingtheguidanceofSection3oftheGL.Repairtubesthatexceedthevoltagelimits.Flaw-like signalsadjacenttotheTSP,withbobbinvoltageslessthanorequalto2volts,willbeallowedtoremaininservice.Flaw-like indications adjacenttotheTSP,withabobbinvoltageofgreaterthan2voltsbutlessthanorequaltouppervoltagerepairlimit,mayremaininserviceifMRPCinspection doesnotdetectaflaw.Flawindications withavoltageofgreaterthantheuppervoltagerepairlimitwillberepaired.
Determine theBeginning ofCycle(BOC)voltagedistribution.
Beginning ofCyclevoltagedistribution willbeestablished fromtheactualtubeinspections tobeperformed andwillbeestablished usingcurrentprogrammethodology.
ProjecttheEOCdistribution.
AnEOCvoltagedistribution willbeestablished basedontheEOCeddycurrenttestdata.EOCvoltagedistribution willbeprojected usingMonteCarlotechniques asdescribed inWCAP-hI1 Attachment 1toAEP:NRC:1166AA Page614277andwillincludeallowance foreddycurrentuncertainty asdefinedinGL95-05andaconservative voltagegrowthrateallowance.
Fortheprojected EOCvoltagedistribution, calculate boththeprimary-to-secondary leakageunderpostulated accidentconditions andtheconditional tubeburstprobabili ty.Asanalternative, theactualmeasuredEOCvoltagedistribution canbeusedwhenitisimpractical tocompletethe,projected EOCcalculation priortoreturning theSGstoserviceforthepurposeofdetermining whetherthereporting criteriainGI95-05Sections6.a.land6.a.3apply.Steamlinebreakleakagewillbecalculated, asdescribed inWCAP-14277,basedontheEOCprojected voltagedistribution.
Projected leakagemustremainbelow8.4gpminthefaultedloopforpermissible offsitedoseestimates toremainacceptable within10Xofthe10CFR100guidelines.
The8.4gpmleakageforoffsitedoseestimates issmallerthantheleakagenumbercalculated foracceptable controlroomdoseperGeneralDesignCriteria(GDC)19.Therefore, theoffsitedoseismorelimiting.
Conditional tubeburstprobability willbecalculated according tothemethodology described inWCAP-14277.
Consistent withGL95-05,ifburstprobability isfoundtobegreaterthan1x10~theNRCwillbeconsulted.
Asprescribed inGL95-05,anevaluation ofprimary-to-secondary leakage(andsubsequently offsitedose)isrequiredforallplantsimplementing thepluggingcriteria.
Allbobbincoilindications areincludedintheSLBleakageanalyses, alongwithconsideration oftheprobability ofdetection.
Iftheprojected leakageexceeds8.4gpminthefaultedloopduringapostulated SLBevent,thenumberofindications towhichthepluggingcriteriaareappliedisreduced,throughtuberepair,untiltheprimary-to-secondary leakagelimitsaresatisfied.
EVALUATION TubeDegradation Characterization Ingeneral,thedegradation morphology occurring attheTSPintersections atplantsintheU.S.canbedescribed asaxiallyorientedODSCC.Thedegradation morphology atCookNuclearPlantUnit1isentirelycompatible withtheoverallindustrydatabase.
Attachment 1toAEP:NRC:1166AA Page7SteamGenerator TubeIntegrity Inthedevelopment ofapluggingcriteriaforCookNuclearPlantUnit1,Regulatory Guide(RG)1.121,"BasesforPluggingDegradedPWRSteamGenerator Tubes"andRGl.'83,"In-service Inspection ofPWRSteamGenerator Tubes"areusedasthebasesfordetermining thatSGtubeintegrity ismaintained withinacceptable limits.Regulatory Guide1.121describes amethodacceptable totheNRCstaffformeetingGDC14,15,31,and32byreducingtheprobability andconsequences ofSGtuberupturebydetermining thelimitingsafeconditions oftubewalldegradation beyondwhichtubeswithunacceptable
- cracking, asestablished byin-service inspection, shouldberemovedfromservicebyplugging.
Thisregulatory guideusessafetyfactorsonloadsfortubeburststhatareconsistent withtherequirements ofSectionIIIoftheASMECode.FortheTSPelevation degradation occurring intheCookNuclearPlantUnit1SGs,tubeburstcriteriaareinherently satisfied duringnormaloperating conditions bythepresenceoftheTSP.ThepresenceoftheTSPenhancestheintegrity ofthedegradedtubesinthatregionbyprecluding tubedeformation beyondthediameterofthedrilledhole,thusprecluding tubeburst.Conservatively, nocreditistakeninthedevelopment ofthepluggingcriteriaforthepresenceoftheTSPduringaccidentconditions.
Basedontheexistingdatabasefor7/8inchtubing,bursttestingindicates thatthesafetyrequirements fortubeburstmarginsduringaccidentcondition loadingcanbesatisfied withEOCbobbincoilsignalamplitudes lessthan8.8volts,regardless ofthedepthoftubewallpenetration ofthecracking.
Uponimplementation oftheproposedpluggingcriteriaprogram,tubeleakageconsiderations mustalsobeaddressed.
Itmustbedetermined thatthecrackswillnotleakexcessively duri~gallplantconditions.
Forthe2voltinterimtubepluggingcriteriadeveloped fortheCookNuclearPlantUnit1SGtubes,noleakageisanticipated duringnormaloperating conditions evenwiththepresenceofpotential throughwall cracks.Noprimary-to-secondary leakageattheTSPhasbeendetectedinU.S.plants.Relativetotheexpectedleakageduringaccidentcondition loading,thelimitingeventwithrespecttodifferential pressureexperienced acrosstheSGtubesisapostulated SLBevent.For7/8inchtubing,pulledtubedatasupportsnoleakageupto2.81voltsandlowprobability ofleakagebetween2.81and6.0volts,forbothpulledtubesandmodelboilerspecimens, attheboundingSLBpressuredifferential of2560psi.Steamlinebreakprimary-to-secondary leakagewillbecalculated asprescribed inGL95-05andWCAP14277,usingprojected EOCeddycurrentdata.Thiscalculated leakagemustbeshowntobelessthan8.4gpminthefaultedloop.
I Attachment 1toAEP:NRC:1166AA Page8Additional Considerations
~*Theproposedamendment wouldprecludeoccupational radiation exposurethatwouldotherwise beincurredbypersonnel involvedintubepluggingorrepairoperations.
Byreducingnon-essential tubeplugging, theproposedamendment wouldminimizethelossofmargininthereactorcoolantflow,throughtheSGs,usedinLOCAanalyses.
Theproposedamendment wouldavoidlossofmargininreactorcoolantsystemflowand,therefore, assistinmaintaining minimumflowratesinexcessofthatrequiredforoperation atfullpower.Reduction intheamountoftuberepairrequiredcanreducethelengthofplantoutagesandreducethetimethattheSGsareopentothecontainment environment duringanoutage.A100Xeddycurrentbobbincoilprobeinspection associated withimplemen'tation ofthepluggingcriteriaprogramwillhelptoidentifynewareasofconcernwhichmayarise,byproviding alevelofin-service inspection whichisfarinexcessoftheT/Srequirements utilizing the40Xdepth-based plugginglimitforacceptable tubewalldegradation.
SIGNIFICANT HAZARDSANALYSISInaccordance withthethreefactortestof10CFR50.92(c),
implementation oftheproposedlicenseamendment isanalyzedusingthefollowing standards andfoundnotto:1)involveasignificant increaseintheprobability orconsequences ofanaccidentpreviously evaluated; 2)createthepossibility ofanewordifferent kindofaccidentfromanyaccidentpreviously evaluated; or3)involveasignificant reduction inmarginofsafety.Conformance oftheproposedamendment tothestandards foradetermination ofnosignificant hazardsasdefinedin10CFR50.92(threefactortest)isshowninthefollowing paragraphs:
1)Operation ofCookNuclearPlaneUnit1,inaccordance withtheproposedlicenseamendment, doesnotinvolveasignificant increaseintheprobability orconsequences ofanaccidentpreviously evaluated.
Testingofmodelboilerspecimens forfreespantubing(noTSPrestraint) atroomtemperature conditions showburstpressures inexcessof5000psiforindications ofouterdiameterstresscorrosion crackingwithvoltagemeasurements ashighas19volts.Bursttestingperformed onpulledtubesfromCookNuclearPlantUnit1withuptoa2.02voltindication showsmeasuredburstpressureinexcessof10,000psiatroomtemperature.
Bursttestingperformed onpulledtubesfromotherplantsshowburstpressures inexcessof5,300psiatroomtemperatures.
Correcting fortheeffectsoftemperature onmaterialproperties andminimumstrengthlevels(astheburst
Attachment 1toAEP:NRC:1166AA Page9testingwasdoneatroomtemperature),
tubeburstresistance significantly exceedsthesafetyfactorrequirements ofRG1.121.Asstatedearlier,tubeburstcriteriaareinherently satisfied duringnormaloperating conditions duetotheproximity oftheTSP.Testdataindicates thattubeburstcannotoccurwithintheTSP,evenfortubeswhichhave100Xthroughwall electric-discharge machinednotches0.75inchlong,providedtheTSPisadjacenttothenotchedarea,Sincetube-to-tube supportplateproximity precludes tubeburstduringnormaloperating conditions, itfollowsthatuseoftheproposedpluggingcriteriamust,therefore, retaintubeintegrity characteristics whichmaintaintheRG1.121marginofsafetyof1.43timestheboundingfaultedcondition (steamlinebreak)pressuredifferential.
Duringapostulated mainSLB,theTSPhasthepotential todeflectduringblowdown, therebyuncovering theintersection.
Basedontheexistingdatabase,theRG1.121criterion requiring maintenance ofasafetyfactorof1.43timestheSLBpressuredifferential ontubeburstissatisfied by7/8inchdiametertubingwithbobbincoilindications withsignalamplitudes lessthanV><,regardless oftheindicated depthmeasurement.
A2voltpluggingcriteriacomparesfavorably withthecurrentV><(8.8volt)structural limit,considering thepreviously calculated growthratesforODSCCwithinCookNuclearPlantUnit1SGs.Considering avoltagegrowthcomponent of0.8volts(40Xvoltagegrowthbasedon2voltsBOC)andanondestructive examination uncertainty of0.40volts(20Xvoltageuncertainty basedon2voltsBOC),whenaddedtotheBOCpluggingcriteriaof2volts,resultsinaboundingEOCvoltageofapproximately 3.2voltsforacycleoperation.
A5.6voltsafetymarginexists(8.8-3.2voltEOC-5.6voltmargin).Forthevoltage/burst correlation, theEOCstructural limitissupported byavoltageof8.8volts.UsingthisVz<of8.8volts,aBOCmaximumallowable repairlimitcanbeestablished usingtheguidanceofRG1.121.TheBOCmaximumallowable repairlimitshouldnotpermitasignificant numberofEOCindications toexceedtheVz<andshouldassurethatacceptable tubeburstprobabilities areattained.
ByaddingNDEuncertainty allowances andanallowance forcrackgrowthtotherepairlimit,thestructural limitcanbevalidated.
Thepreviouspluggingcriteriasubmittal established theconservative NDEuncertainty limit(V<><)of20XoftheBOCrepair-limit.Forconsistency, a40Xvoltagegrowthallowance (V<<)totheBOCrepairlimitisalsoincluded.
Thisallowance isextremely conservative forCookNuclear
Attachment 1toAEP:NRC:1166AA Page10PlantUnit1.Therefore, themaximumallowable uppervoltagerepairlimitV<<<forBOC,basedontheV><of8.8volts,canberepresented bytheexpression:
VURL+(VADExVURL)+(VMxVuRL)=8.8volts,or,themaximumallowable BOCrepairlimitcanbeexpressed as,Vz<<=8.8voltstructural limit/1.6
=5.5volts.Thisstructural repairlimitsupportsthisapplication forpluggingcriteriaimplementation torepairbobbinindications greaterthan2voltsbasedonRPCconfirmation oftheindication.
Conservatively, anupperlimitof5.5voltswillbeusedtorepairbobbincoilindications whichareabove2voltsbutdonothaveconfirming RPCcalls.Relativetotheexpectedleakageduringaccidentcondition
- loadings, ithasbeenpreviously established thatapostulated mainSLBoutsideofcontainment, butupstreamofthemainsteamisolation valve,represents themostlimitingradiological condition relativetothepluggingcriteria.
Insupportofimplementation ofthepluggingcriteria, itwillbedetermined whetherthedistribution ofcrackindications attheTSPintersections attheEOCareprojected tobesuchthatprimary-to-secondary leakagewouldresultinsiteboundarydoseswithinasmallfractionofthe10CFR100guidelines.
Aseparatecalculation hasdetermined thisallowable SLBleakagelimittobe8.4gpm.AlthoughnotrequiredbytheCookNuclearPlantdesignbasis,thiscalculation usestherecommended Iodine-131 transient spikingvaluesconsistent withNUREG-0800, andtheT/Sreactorcoolantsystemactivitylimi,tof1microcuriepergramdoseequivalent Iodine-131.
Controlroomdosecalculations werealsoperformed andfoundtobelesslimitingthantheoffsitedosecalculation leakrate.
Therefore, themoreconservative offsitedoseleakrateisused.Theprojected SLBleakageratecalculation methodology prescribed inGL95-05andWCAP14277willbeusedtocalculate EOCleakage,basedonactualEOCdistributions andEOCprojected distributions.
Duetotherelatively lowvoltagegrowthratesatCookNuclearPlantUnit1andtherelatively smallnumberofindications affectedbythepluggingcriteria, SLBleakageprediction perGL95-05isexpectedtobesignificantly lessthanthepermissible level.of8.4gpminthefaultedloop.Theinclusion ofallintersections intheleakagemodel,alongwithapplication ofaprobability ofdetection of0.6,
Attachment 1toAEP:NRC:1166AA Page11willresultinextremely conservative leakageestimations.
Closeexaminat'ion oftheavailable datashowsthatindications oflessthan2.8voltswillnotbeexpectedtoleakduringSLBconditions.
Theproposedamendment doesnotresultinanyincreaseintheprobability orconsequences ofanaccidentpreviously evaluated withintheCookNuclearPlantUnit1FinalSafetyAnalysisReport(FSAR).2)Theproposedlicenseamendment doesnotcreatethepossibility ofanewordifferent kindofaccidentfromanyaccidentpreviously evaluated.
Implementation oftheproposedSGtubepluggingcriteriadoesnotintroduce anysignificant changestotheplantdesignbasis.Useofthecriteriadoesnotprovideamechanism whichcouldresultinanaccidentoutsideoftheregionoftheTSPelevations.
Neitherasinglenoramultipletuberuptureeventwould,underanyplantconditions, beexpectedinaSGinwhichthepluggingcriteriahasbeenapplied.Specifically, wewillcontinuetoimplement amaximumleakageratelimitof150gpd(0.1gpm)perSGtohelpprecludethepotential forexcessive leakageduringallplantconditions.
TheT/Slimitsimposedonprimary-to-secondary leakageatoperating conditions areamaximumof0.4gpm(600gpd)forallSGswithamaximumof150gpdallowedforanyoneSG~TheRG1.121criteriaforestablishing operational leakageratelimitsthatrequireplantshutdownarebaseduponleak-before-break (LBB)considerations todetectafreespancrackbeforepotential tuberuptureduringfaultedplantconditions.
The150gpdlimitshouldprovideforleakagedetection andplantshutdownintheeventoftheoccurrence ofanunexpected singlecrackresulting inleakagethatisassociated withthelongestpermissible cracklength.Regulatory Guide1.121acceptance criteriaforestablishing operating leakagelimitsarebasedonLBBconsiderations suchthatplantshutdownisinitiated iftheleakageassociated withthelongestpermissible crack,isexceeded.
Thelongestpermissible crackisthelengththatprovidesafactorofsafetyof1.43againstburstingatfaultedconditions maximumpressuredifferential.
Avoltageamplitude of8.8voltsfortypicalODSCCcorresponds tomeetingthistubeburstrequirement atalower95/prediction limitontheburstcorrelation coupledwith95/95lowertolerance limitmaterialproperties.
Alternate crackmorphologies cancorrespond to
Attachment 1toAEP:NRC:1166AA Page128.8voltssothatauniquecracklengthisnotdefinedbytheburstpressure"versusvoltagecorrelation.
Consequently, typicalburstpressureversusthrough-wall cracklengthcorrelations wereusedtodefinethe"longestpermissible crack"forevaluating operating leakagelimits.Consistent withthecycle13,14and15licenseamendment requestsforpluggingcriteria, andSection5ofEnclosure 1oftheGL,operational leakagelimitswillremainat150gpd.perSG.AxialcracksleakingatthislevelareexpectedtoprovideLBBprotection atboththeSLBpressuredifferential of2560psiand,whilenotpartofanyestablished LBBmethodology, LBBprotection willalsobeprovidedatavalueof1.43timestheSLBpressuredifferential.
Thus,the150gpdlimitprovidesforplantshutdownpriortoreachingcriticalcracklengthsforSLBconditions.
Additionally, thisLBBevaluation assumesthattheentirecreviceareaisuncovered duringblowdown.
Partialuncoverywillprovidebenefittotheburstcapacityoftheintersection.
3)Theproposedlicenseamendment doesnotinvolveasignificant reduction inmarginofsafety.Theuseofthevoltage-based bobbinprobeinterimTSPelevation pluggingcriteriaatCookNuclearPlantUnit1isdemonstrated tomaintainSGtubeintegrity commensurate withthecriteriaofRG1.121.Regulatory Guide1~121describes amethodacceptable totheNRCstaffformeetingGDC14,15,31,and32byreducingtheprobability ortheconsequences ofSGtuberupture.Thisisaccomplished bydetermining thelimitingconditions ofdegradation ofSGtubing,asestablished byin-service inspection, forwhichtubeswithunacceptable crackingshouldberemovedfromservice.Uponimplementation ofthecriteria, evenundertheworstcaseconditions, theoccurrence ofODSCCattheTSPelevations isnotexpectedtoleadtoaSGtuberuptureeventduringnormal,orfaultedplantconditions.
Itwillbeconfirmed byanalysisandcalculation thatEOCdistribution ofcrackindications attheTSPelevations willresultinacceptable primary-to-secondary leakageduringallplantconditions andthatradiological consequences arenotadversely impacted.
Inaddressing thecombinedeffectsofaLOCAandSSEontheSGcomponent (asrequiredbyGDC2),ithasbeendetermined thattubecollapsemayoccurintheSGsatsomeplants.Thepostulated tubecollapseresultsfromadeformation ofTSPsasaresultoflateralloadsatthewedgesupportsattheperiphery oftheplate.Thelateralloadsresultfromthe l
Attachment 1toAEP:NRC:1166AA Page13combinedeffectsoftheLOCArarefaction waveandSSEloadings.
Theresulting pressuredifferential onthedeformedtubesmaythencausesomeofthetubestocollapse.
Therearetwoissuesassociated withapostulated SGtubecollapse.
First,thecollapseofSGtubingreducestheRCSflowareathroughthetubes.Thereduction inflowareaincreases theresistance toflowofsteamfromthecoreduringaLOCAwhich,inturn,maypotentially increasepeakcladtemperature.
Second,thereisapotential thatpartialthrough-wall cracksintubescouldprogresstothrough-wall cracksduringtubedeformation orcollapse.
Consequently, sincetheLBBmethodology isapplicable totheCookNuclearPlantUnit1reactorcoolantlooppiping,theprobability ofbreaksintheprimarylooppipingissufficiently lowthattheyneednotbeconsidered inthestructural designoftheplant.ThelimitingLOCAeventbecomeseithertheaccumulator linebreakorthepressurizer surgelinebreak.LossofcoolantaccidentloadsfortheprimarypipebreakswereusedtoboundtheCookNuclearPlantUnit1smallerbreaks.TheresultsoftheanalysisusingthelargerbreakinputsshowthattheLOCAloadswerefoundtobeofinsufficient magnitude toresultinSGtubecollapseorsignificant deformation.
Addressing RG1.83considerations, implementation of,thebobbincoilprobe,voltage-based interimtubepluggingcriteriaof2voltsissupplemented byenhancededdycurrent,inspection guidelines toprovideconsistency involtagenormalization, a100Xeddycurrentinspection samplesizeattheTSPelevations perT/S,andMRPCinspection requirements forthelargerindications leftin-service tocharacterize theprincipal degradation asODSCC.Asnotedpreviously, implementation oftheTSPelevation pluggingcriteriawilldecreasethenumberoftubeswhichmustberepaired.
Theinstallation ofSGtubeplugsreducestheRCSflowmargin.Thus,implementation ofthepluggingcriteriawillmaintainthemarginofflowthatwouldotherwise bereducedintheeventofincreased tubeplugging.
Basedontheabove,itisconcluded thattheproposedlicenseamendment requestdoesnotresultinasignificant reduction inmarginwithrespecttoplantsafetyasdefinedintheFSARoranyBasesoftheplantT/Ss.
I,