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{{#Wiki_filter:LERATEDDI,UTIONDEMONS' | {{#Wiki_filter:LERATEDDI,UTIONDEMONS'ION SYSTEMREGULATORY INFORMATION DISTRIBUTION SYSTEM(RIDS)ACCESSION NBR:9402240387 DOC.DATE: | ||
94/02/15NOTARIZED: | |||
YESDOCKETFACIL:50-315 DonaldC.CookNuclearPowerPlant,Unit1,IndianaM05000315AUTH.NAMEAUTHORAFFILIATION FITZPATRICK,E. | |||
IndianaMichiganPowerCo.(formerly Indiana6MichiganEleRECIP.NAME RECIPIENT AFFILIATION MURLEY,T.E. | |||
DocumentControlBranch(Document ControlDesk)R | |||
==SUBJECT:== | ==SUBJECT:== | ||
Application foramendtoLicenseDPR-58,incorporating | |||
==2.0 voltsteamgenerator== | |||
tubesupportplateinterimpluggingcriteriaforCycle14.DISTRIBUTION CODE:A001DCOPIESRECEIVED:LTR ENCLSIZETITLE:ORSubmittal: | |||
GeneralDistribution NOTES:RECIPIENT IDCODE/NAME PD3-1LAHICKMAN,J INTERNALNRR/DE/EELB NRR/DRCH/HICB NRR/DSSA/SPLB NUDOCS-ABSTRACT OGC/HDS2EXTERNAL: | |||
NRCPDRCOPIESLTTRENCL1122111111111011RECIPIENT IDCODE/NAME PD3-1PDNRR/DORS/OTS BNRR/DRPWNRR/DSSA/SRXB | |||
-e/"BPBCBEGFI01NSICCOPIESLTTRENCL11111111101111DDDNOTETOALL"RIDS"RECIPIENTS: | |||
DDPLEASEHELPUSTOREDUCEWASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMPl-37(EXT.20079)TOELIMINATE YOURNAMEFROMDISTRIBUTION LINISFORDOCUMENTS YOUDON'TNEED!TOTALNUMBEROFCOPIESREQUIRED: | |||
LTTR16ENCL14 0414 IndianaNlchiganPowerCompanyP.O.Box16631Columbus, OH43216IAEP:NRC:1166L DonaldC.CookNuclearPlantUnit1DocketNo.50-315LicenseNo,DPR-58TECHNICAL SPECIFICATION CHANGESTOINCORPORATE | |||
==2.0 VOLTINTERIMSTEAMGENERATOR== | |||
TUBESUPPORTPLATEPLUGGINGCRITERION FORFUELCYCLE14U.S.NuclearRegulatory Commission DocumentControlDeskWashington, D.C.20555Attn:T.EDMurleyFebruary15,1994 | |||
==DearDr.Murley:== | ==DearDr.Murley:== | ||
Thisletteranditsattachments constitute anapplication foranexigentamendment totheTechnical Specifications (T/Ss)fortheDonaldC.CookNuclearPlantUnit1,Specifically, wearerequesting toincorporate a2.0voltsteamgenerator tubesupportplateinterimpluggingcriterion forFuelCycle14.Asdiscussed withyourstaffonFebruary9,1994,thereasonformakingtherequestonanexigentbasisisthatthechangeisassociated withsteamgenerator repairsduringthecurrentUnit1refueling outage.Therepairsarecurrently scheduled tobeginMarch6,1994.Therefore, werequestapprovalofthisamendment requestbyMarch4inordertoavoidoutagedelays.ByletterdatedDecember15,1993(AEP:NRC:1166H), | |||
werequested similarsteamgenerator tubeinterimpluggingcriteriaT/Schanges.Thisletterdoesnotsupersede theprevioussubmittal. | |||
Thechangesdifferfromourprevioussubmittal inthatthissubmittal incorporates a2.0voltcriterion versustheprevious1.0voltlimit.Theuppervoltagelimitfordisposition ofindications byrotatingpancakecoilinspection isalsochangedfrom3.1voltsto3.6volts.Additionally, predicted end-of-cycle leakageinthefaultedloopforapostulated steamline breakislimitedto12.6gpm,versus1.0gpm.Thisisbasedonaradiological analysisperformed inaccordance withtheStandardReviewPlan,including iodinespikingandT/Sreactorcoolantsystemactivitylimits.TheT/Schangesrequested inthissubmittal aresimilartoaDecember9,1993,requestmadebytheFarleyNuclearPlantUnit1.9402240387 940215PDRADOCK05000315I;.P.PDRgdOlI(I IIIpI Dr.T.E.Murley2AEP:NRC:1166L Asdiscussed withyourstaffonFebruary9,arotatingpancakecoilinspection willbeperformed foralltubeswithanindication above1.0volt,despitethechangeintheinterimpluggingcriteriato2.0volts.Itisanticipated thatthestandardbobbinprobe(0.720inches)willbetheprobeusedfortubepluggingdetermination inconjunction withtheinterimpluggingcriteria. | |||
Ifasmallerbobbinprobeisused,itisourunderstanding thatitsusemustbesupported byarigorousstatistical analysis. | |||
Ifthesmallerbobbinprobeistobeused,thedetailsofthestatistical analysiswillbethesubjectofseparatecorrespondence. | |||
Asdiscussed inoursubmittal AEP:NRC:1166H, westatedourpositionregarding notremovingtubesduringthe1994refueling outage.Changingtheinterimpluggingcriteriafrom1.0to2.0voltsdoesnotchangethebasisforourposition. | |||
~~~~~ | Also,thatsubmittal providedanappendixentitled"NDEDataAcquisition andAnalysisGuidelines." | ||
AlthoughthisappendixwaswrittenspecifictoanIPCof1.0volts,itisstillapplicable inthegeneralsensewithanIPCof2.0volts,andtherefore, perdiscussions withyourstaffofFebruary9,1994,willnotberevisedforthisletter.Attachment 1containsadescription oftheproposedT/Schangesaswellasthe10CFR50.92nosignificant hazardsevaluation. | |||
Attachment 2containstheexistingT/Spagesmarkedtoreflectthechanges.Attachment 3containstheproposedrevisedT/Spages.Attachment 4containstheradiological analysisthatsupportsthe12.6gpmend-of-cycle leakagelimitdiscussed above.Webelievetheproposedchangeswillnotresultin(1)asignificant changeinthetypesofanyeffluentthatmaybereleasedoffsite,or(2)asignificant increaseinindividual orcumulative occupational radiation exposure. | |||
TheseproposedchangeshavebeenreviewedbythePlantNuclearSafetyReviewCommittee andbytheNuclearSafetyandDesignReviewCommittee. | |||
Incompliance withtherequirements of10CFR50.91(b)(l), | |||
copiesofthisletteranditsattachments havebeentransmitted totheMichiganPublicServiceCommission andtotheMichiganDepartment ofPublicHealth.Thisletterissubmitted pursuantto10CFR50.30(b), | |||
and,assuch,anoathstatement isattached. | |||
Sincerely, EFE.E.Fitzpatrick VicePresident Dr.T.E.Murley3AEP:NRC:1166L drAttachments cc:A.A.BlindG.CharnoffJ.B.Martin-RegionIIINFEMSectionChiefNRCResidentInspector J.R.Padgett STATEOFOHIO)COUNTYOFFRANKLIN) | |||
E.E.Fitzpatrick, beingdulysworn,deposesandsaysthatheistheVicePresident oflicenseeIndianaMichiganPowerCompany,thathehasreadtheforgoingTECHNICAL SPECIFICATION CHANGESTOINCORPORATE | |||
==2.0 VOLTINTERIMSTEAMGENERATOR== | |||
TUBESUPPORTPLATEPLUGGINGCRITERION FORFUELCYCLE14andknowsthecontentsthereof;andthatsaidcontentsaretruetothebestofhisknowledge andbelief.Subscribed andsworntobeforemethis/W~dayofNOTARYPUBLICRITAD.HILLSOTARYPUBLIC.STATOFOHIOaVCOhIh'IISSIOH EXPIRE-~X r4I/ | |||
ATTACHMENT 1TOAEP:NRC:1166L DESCRIPTION ANDJUSTIFICATION OFCHANGES10CFR50.92ANALYSISFORCHANGESTOTHEDONALDC.COOKNUCLEARPLANTUNIT1TECHNICAL SPECIFICATIONS Attachment 1toAEP:NRC:1166L Page1I.INTRODUCTION Thisamendment requestproposesachangetoT/S4.4.5(SteamGenerators) toincorporate arevisedcriterion forsteamgenerator tubesupportplateinterimpluggingcriterion (IPC).Thechangesallowsteamgenerator tubeswithindications lessthanorequalto2.0voltstoremaininservice,regardless ofdepthoftubewallpenetration, ifasaresult,theprojected end-of-cycle (EOC)distribution ofcrackindications isverifiedtoresultinprimary-to-secondary leakagelessthan12.6gpminthefaultedloopduringapostulated steamline breakevent.Indications greaterthan2.0voltsbutlessthanorequalto3.6voltscanremaininserviceifarotatingpancakecoilprobe(RPC)inspection doesnotdetectdegradation. | |||
Theamendment requestisspecifictoFuelCycle14only.Thepurposeoftheamendment istoreducethenumberoftubesrequiredtobeplugged.ThishasbenefitsbothfromanALARAperspective aswellastheperspective ofmaximizing RCSflowmargin.A1.0voltIPCwasgrantedforCookNuclearPlantUnit1,viaT/SAmendment 166,forthepreviousfuelcycle(Cycle13).ByletterdatedDecember15,1993(AEP:NRC:1166H), | |||
werequested similarsteamgenerator tubeinterimpluggingcriteriaT/SchangesforCycle14.Thisletterdoesnotsupersede theprevioussubmittal. | |||
Thechangesdifferfromourprevioussubmittal inthatthissubmittal incorporates a2.0voltcriteriaversustheprevious.1.0voltlimit.TheuppervoltagelimitforRPCconfirmation ischangedfrom3.1voltsto3.6volts.Additionally, predicted end-of-cycle leakageinthefaultedloopforapostulated steamline breakislimitedto12.6gpm,versus1.0gpm.Thisisbasedon'aradiological analysisperformed inaccordance withtheStandardReviewPlan,including iodinespikingandT/Slimitsonreactorcoolantsystemactivity. | |||
(Theprevioussubmittal didnotincludetheeffectsofiodinespikingonthedoseanalysisandassumedreactorcoolantactivitycorresponding to1%failedfuel.)TheT/Schangesrequested inthissubmittal aresimilartoaDecember9,1993,requestmadebytheFarleyNuclearPlantUnit1.Asdiscussed withyourstaffonFebruary9,anRPCinspection willbeperformed foralltubeswithanindication above1.0volt,despitethechangeintheinterimpluggingcriteriafrom1.0voltto2.0volts.Itisanticipated thatthestandardbobbinprobe(0.720inches)willbetheprobeusedfortubepluggingdetermination inconjunction withtheinterimpluggingcriteria. | |||
Ifasmallerbobbinprobeisused,itisourunderstanding thatitsusemustbesupported byarigorousstatistical analysis. | |||
Ifthesmallerbobbinprobeistobeused,thedetailsofthestatistical analysiswillbethesubjectofseparatecorrespondence. | |||
Attachment 1toAEP:NRC:1166L Page2Our1.0voltIPCsubmittal (AEP:NRC:1166H) providedanappendixentitled"NDEDataAcquisition andAnalysisGuidelines." | |||
AlthoughthisappendixwaswrittenspecifictoanIPCof1.0volt,itisstillapplicable inthegeneralsensewithanIPCof2.0volts,andtherefore, perdiscussions withyourstaffofFebruary9,1994,willnotberevisedforthissubmittal. | |||
Assessment ofIPCMethodolo Anassessment ofthemethodology described inWCAP-13187, Revision0willbeconducted fortheIPC.Itwilladdressdiscrepancies betweenpredicted andactualEOCvoltagedistributions. | |||
Theassessment willinclude:a.EOC12voltagedistribution | |||
-indications foundduringtheinspection regardless ofRPCverification results.b.Cycle12growthrate(i.e.frombeginning ofcycle(BOC)12toEOC12).c~EOC12repairedindications voltagedistribution distribution ofindications presented in(a)abovethatwererepaired(ifpluggedorsleeved). | |||
d.Voltagedistribution forindications leftinserviceattheBOC13regardless ofRPCconfirmation | |||
-obtainedfrom(a)and(c)above.e.Voltagedistribution forindications leftinserviceattheBOC13thatwereconfirmed byRPCtobecrack-like ornotRPCinspected. | |||
Non-destructive examination uncertainty distribution usedinpredicting theEOC13voltagedistribution. | |||
goProjected EOC13voltagedistribution usingthemethodology inWCAP-13187, Revision0.h.ActualEOC13voltagedistribution | |||
-indications foundduringtheinspection regardless ofRPCconfirmation. | |||
Cycle13growthrate(i.e.fromBOC13toEOC13).EOC13repairedindications voltagedistribution distribution ofindications presented in(h)abovethatwererepaired(i.e.pluggedorsleeved). | |||
Attachment 1toAEP:NRC:1166L Page3k.Voltagedistribution forindications leftinserviceattheBOC14regardless ofRPCconfirmation | |||
-obtainedfrom(h)and(j)above.1.Voltagedistribution forindications leftinserviceattheBOC14thatwereconfirmed byRPCtobecrack-like ornotRPCinspected. | |||
m.Nondestructive examination uncertainty distribution usedinpredicting theEOC14voltagedistribution. | |||
n.Projected EOC14voltagedistribution usingthemethodology inWCAP-13187, Revision0.Thetotalassessment, (a)through(n)willbesubmitted approximately 10weeksfromcompletion ofsteamgenerator inspections. | |||
However,perT/Srequirements thesteamline breakleakageanalysisperformed underT/S4.4.5.4.a.10 willbereportedtotheNRCStaffpriortorestartforFuelCycle14.II.SCTIONOFTHECHANGESTheproposedchangesarethosenecessary toincorporate a2.0voltIPCforCookNuclearPlantUnit1FuelCycle14.Thespecificchangesareasfollows:1.TS4452d4455e3462cBases3445Bases34462Reference toFuelCycle13fortheIPCischangedtoFuelCycle14.Thedefinition ofIPCismodifiedsuchthatsteamgenerator tubeswithindications lessthanorequalto2.0volts(vs.1.0volt)canremaininservice,regardless ofdepthoftubewallpenetration, ifasaresult,theprojected end-of-cycle distribution ofcrackindications isverifiedtoresultinprimary-to-secondary leakagelessthan12.6gpm(vs.1.0gpm)inthefaultedloopduringapostulated steamline breakevent.Indications greaterthan2.0voltsbutless'hanorequalto3.6volts(vs.1.0voltand4.0volts)canremaininserviceifaRPCinspection doesnotdetectdegradation. | |||
Attachment 1toAEP:NRC:1166L Page4Theend-of-cycle primarytosecondary leakagemustbelessthan12.6gpminthefaultedloop,versusthepresent1.0gpm,forapostulated steamline breakevent.Theleakageassumedintheaccidentanalysisischangedfrom120gpmto12.6gpm(fortheCycle14IPConly).III.10CFR5092EVALUATION BACKGROUND CookNuclearPlantUnit1T/SAmendment 166permitted theimplementation ofa1.0voltsteamgenerator tubeinterimpluggingcriteria(IPC)forthe13thoperating cycleoftheCookNuclearPlantUnit1steamgenerators. | |||
Thislicenseamendment wasapplicable onlyforthepreviouscycle(Cycle13),andrequiredtherepairofflaw-like bobbinindications above1.0volt.BasedupontubepullresultsfromCookNuclearPlantUnit1andotherplantsgatheredsincethestartofCycle13,weareproposing useofa2.0voltinterimrepaircriterion fortheupcomingCycle14.DESCRIPTION OFTHEIPCREQUESTAsrequiredby10CFR50.91(a)(l),ananalysisisprovidedtodemonstrate thattheproposedlicenseamendment toimplement aninterimtubepluggingcriteriaforthetubesupportplateelevation outerdiameterstresscorrosion cracking(ODSCC)occurring intheCookNuclearPlantUnit1steamgenerators involvesanosignificant hazardsconsideration. | |||
TheIPCutilizescorrelations betweeneddycurrentbobbinprobesignalamplitude (voltage) andtubeburstandleakagecapability. | |||
Thepluggingcriteriaisbasedontestingoflaboratory inducedODSCCspecimens, andextensive examination ofpulledtubesfromoperating steamgenerators (industry wideincluding 3tubesrepresenting 6intersections fromtheCookNuclearPlantUnit1steamgenerators.) | |||
Theinterimpluggingcriteriacanbedescribed bythefollowing elements: | |||
A1008bobbincoilinspection ofhotlegtubesupportplateintersections andcoldlegintersections downtothelowestcoldlegtubesupportplatewithknownODSCCindications willbeperformed. | |||
2.Flaw-like signalsadjacenttothetubesupportplateswithbobbinvoltageslessthanorequalto2.0voltswil'1beallowedtoremaininservice. | |||
Attachment 1toAEP:NRC:1166L Page53.Flaw-like signalsadjacenttothetubesupportplatewithabobbinvoltageofgreaterthan2.0voltswillberepairedexceptasnotedinItem4.4.Flaw-like signalsadjacenttothetubesupportplatewithabobbinvoltagegreaterthan2.0voltsbutlessthanorequalto3.6voltsmayremaininserviceifRPCinspection doesnotdetectaflaw.Flawindications withabobbinvoltagegreaterthan3.6voltswillberepaired. | |||
5.Aspartofasampleinspection programtohelpensurethatadditional degradation modesarenotoccurring, allflawindications withbobbinvoltagesgreaterthan1.0voltbutlessthanorequalto2.0voltswillbeinspected byRPC.6.Anend-of-cycle voltagedistribution willbeestablished basedupontheend-of-Cycle 13eddycurrentdata.Baseduponthisdistribution, postulated steamline breakleakagewillbeestimated basedontheguidanceofdraftNUREG1477.Projected leakagemustremainbelow12.6gpminthefaultedloopinorderforoffsitedoseestimates toremainwithin10%ofthe10CFR100guidelines. | |||
Asprescribed indraftNUREG-1477, anevaluation ofprimarytosecondary leakage(andsubsequently offsitedose)isrequiredforallplantsimplementing theinterimpluggingcriteria(IPC).PerdraftNUREG-1477, allbobbinindications areincludedinthesteamline breakleakageanalysesalongwiththeconsideration ofprobability ofdetection (POD).Iftheprojected leakageexceeds12.6gpminthefaultedloopduringapostulated steamline breakevent,thenumberofindications inwhichtheinterimpluggingcriteriaareappliedisreducedthroughtuberepairuntiltheprimarytosecondary leakagelimitsaresatisfied. | |||
EVALUATION TubeDegradation Characterization Ingeneral,thedegradation morphology occurring atthetubesupportplateintersections atplantsintheU.S.canbedescribed asaxiallyorientedODSCC.Thedegradation morphology atCookNuclearPlantUnit1isentirelycompatible withtheoverallindustrydatabase.SteamGenerator TubeIntegrity Inthedevelopment ofaninterimpluggingcriteriaforCookNuclearPlantUnit1,Regulatory Guide(RG)1.121,"BasesforPluggingDegradedPWRSteamGenerator Tubes"andRG1.83"Inservice Inspection ofPWRSteamGenerator Tubes"areusedasthebasesfordetermining thatsteam Attachment 1toAEP:NRC:1166L Page6generator tubeintegrity considerations aremaintained withinacceptable limits.RG1.121describes amethodacceptable totheNRCstaffformeetingGeneralDesignCriteria14,15,31,and32byreducingtheprobability andconsequences ofsteamgenerator tuberupturethroughdetermining thelimitingsafeconditions oftubewalldegradation beyondwhichtubeswithunacceptable | |||
: cracking, asestablished byinservice inspection, shouldberemovedfromservicebyplugging. | |||
Thisregulatory guideusessafetyfactorsonloadsfortubeburstthatareconsistent withtherequirements ofSectionIIIoftheASMECode.Forthetubesupportplateelevation degradation occurring intheCookNuclearPlantUnit1steamgenerators, tubeburstcriteriaareinherently satisfied duringnormaloperating conditions bythepresenceofthetubesupportplate.Thepresenceofthetubesupportplateenhancestheintegrity ofthedegradedtubesinthatregionbyprecluding tubedeformation beyondthediameterofthedrilledhole,thusprecluding tubeburst.Conservatively, nocreditistakeninthedevelopment ofthepluggingcriteriaforthepresenceofthetubesupportplateduringaccidentconditions. | |||
Basedontheexistingdatabasefor7/8inchtubing,bursttestingshowsthatthesafetyrequirements fortubeburstmarginsduringaccidentcondition loadingscanbesatisfied withendofcyclebobbincoilsignalamplitudes lessthan9.6volts,regardless ofthedepthoftubewallpenetration ofthecracking. | |||
Uponimplementation ofthepluggingcriteria, tubeleakageconsiderations mustalsobeaddressed. | |||
Itmustbedetermined thatthecrackswillnotleakexcessively duringallplantconditions. | |||
Forthe2.0voltinterimtubepluggingcriteriadeveloped fortheCookNuclearPlantUnit1steamgenerator tubes,noleakageisanticipated duringnormaloperating conditions evenwiththepresenceofpotentially throughwall cracks.Noleakageduringnormaloperating conditions hasbeenobservedinthefieldforcrackindications withsignalamplitudes upto7.7volts(3/4inchtubes).Voltagecorrelation to7/8inchtubingsizewouldresultinanexpectedvoltageofabout10volts.Noprimarytosecondary leakageatthetubesupportplates(TSP)hasbeendetectedinU.S.plants.Relativetotheexpectedleakageduringaccidentcondition | |||
: loadings, thelimitingeventwithrespecttodifferential pressureexperienced acrosstheSGtubesisapostulated steamline breakevent.For7/8inchtubing,pulledtubedatasupportsnoleakageupto2.81volts,andlowprobability ofleakagebetween2.81and6.0volts,forbothpulledtubesandmodelboilerspecimens attheboundingsteamline breakpressuredifferential of2560psi.Steamline breakprimarytosecondary leakagewillbecalculated asprescribed inSection3.3ofdraftNUREG-1477 (usingaprimary-to-secondary pressuredifferential of2560psid)onceEOC13eddycurrentdataisreduced.Thiscalculated leakagemustbeshowntobelessthan12.6gpminthefaultedloop. | |||
~~~~~Attachment 1toAEP;NRC:1166L Page7Additional Considerations Theproposedamendment wouldprecludeoccupational radiation exposurethatwouldotherwise beincurredbypersonnel involvedintubepluggingorrepairoperations. | |||
Byreducingnon-essential tubeplugging, theproposedamendment wouldminimizethelossofmargininthereactorcoolantflowthroughthesteamgenerator inLOCAanalyses. | |||
Theproposedamendment wouldavoidlossofmargininreactorcoolantsystemflowand,therefore, assistindemonstrating thatminimumflowratesaremaintained inexcessofthatrequiredforoperation atfullpower.Reduction intheamountoftuberepairrequiredcanreducethelengthofplantoutagesandreducethetimethatthesteamgenerator isopentothecontainment environment duringanoutage.The1008eddycurrentbobbinprobeinspection associated withimplementation oftheIPCwillhelptoidentifynewareasofconcernwhichmayarisebyproviding alevelofinservice inspection whichisfarinexcessoftheT/Srequirements utilizing the40$depth-based plugginglimitforacceptable tubewalldegradation. | |||
SIGNIFICANT HAZARDSANALYSISInaccordance withthethreefactortestof10CFR50,92(c), | |||
implementation oftheproposedlicenseamendment isanalyzedusingthefollowing standards andfoundnotto1)involveasignificant increaseintheprobability orconsequences ofanaccidentpreviously evaluated; 2)createthepossibility ofanewordifferent kindofaccidentfromanyaccidentpreviously evaluated; or3)involveasignificant reduction inmarginofsafety.Conformance oftheproposedamendment tothestandards foradetermination ofnosignificant hazardsasdefinedin10CFR50.92(threefactortest)isshowninthefollowing: | |||
1)Operation oftheDonaldC.CookNuclearPlantUnit1inaccordance withtheproposedlicenseamendment doesnotinvolveasignificant increaseintheprobability orconsequences ofanaccidentpreviously evaluated. | |||
Testingofmodelboilerspecimens forfreespantubing(notubesupportplaterestraint) atroomtemperature conditions showburstpressures inexcessof5000psiforindications ofouterdiameterstresscorrosion crackingwithvoltagemeasurements ashighas19volts.Bursttestingperformed onpulledtubesfromCookNuclearPlantUnit1withuptoa2.02voltindication showsmeasuredburstpressureinexcessof10,000psiatroomtemperature, Bursttestingperformed onpulledtubesfromotherplantswithupto7.5voltindications showburstpressures inexcessof6,300psiatroomtemperatures. | |||
Correcting fortheeffectsoftemperature onmaterialproperties andminimumstrengthlevels(asthebursttestingwasdoneatroomtemperature), | |||
tubeburstcapability significantly exceedsthesafetyfactorrequirements ofRG1.121.Asstatedearlier,tubeburstcriteriaareinherently satisfied duringnormaloperating conditions duetotheproximity ofthetubesupportplate.Testdataindicates thattubeburstcannotoccurwithinthetubesupport Attachment 1toAEP:NRC:1166L Page8plate,evenfortubeswhichhave100%throughwall electric-discharge machined(EDM)notches0.75inchlong,providedthatthetubesupportplateisadjacenttothenotchedarea.Sincetubetotubesupportplateproximity precludes tubeburstduringnormaloperating conditions, useofthecriteriamustretaintubeintegrity characteristics whichmaintains theR.G.1.121marginofsafetyof1.43timestheboundingfaultedcondition (steamline break)pressuredifferential. | |||
Duringapostulated mainsteamline break,theTSPhasthepotential todeflectduringblowdown, therebyuncovering theintersection. | |||
Basedontheexistingdatabase,theRG1.121criterion requiring maintenance ofasafetyfactorof1.43timesthesteamline breakpressuredifferential ontubeburstissatisfied by7/8inchdiametertubingwithbobbincoilindications withsignalamplitudes lessthan9.6volts,regardless oftheindicated depthmeasurement. | |||
A2.0voltpluggingcriteriacomparesfavorably withthe9.6voltstructural limitconsidering thepreviously calculated growthratesforODSCCwithintheCookNuclearPlantUnit1steamgenerators. | |||
Considering avoltagegrowthcomponent of0,8volts(40%voltagegrowthbasedon2.0voltsBOC)andanNDEuncertainty of0.40volts(20%voltageuncertainty basedon2.0voltsBOC),whenaddedtotheBOCinterimpluggingcriteriaof2.0voltsresultsinaboundingEOCvoltageofapproximately 3.2voltsforCycle14operation. | |||
A6.4voltsafetymarginexists(9.6structural limit-3.2voltEOC-6.4voltmargin).Forthevoltage/burst correlation, theEOCstructural limitissupported byavoltageof9.6volts.Usingthisstructural limitof9.6volts,abeginning ofcycle(BOC)maximumallowable repairlimitcanbeestablished usingtheguidanceofRG1.121.TheBOCmaximumallowable repairlimitshouldnotpermittheexistence ofEOCindications whichexceedthe9.6voltstructural limit.ByaddingNDEuncertainty allowances andanallowance forcrackgrowthtotherepairlimit,thestructural limitcanbevalidated. | |||
PreviousIPCsubmittals haveestablished theconservative NDEuncertainty limitof20$oftheBOCrepairlimit.Forconsistency, a408voltagegrowthallowance totheBOCrepairlimitisalsoincluded. | |||
Thisallowance isextremely conservative forCookNuclearPlantUnit1.Therefore, themaximumallowable BOCrepairlimit(RL)basedonthestructural limitof9.6voltscanberepresented bytheexpression: | |||
RL+(0.2xRL)+(0.4xRL)-9.6volts,or,themaximumallowable BOCrepairlimit(RL)canbeexpressed as,RL9.6voltstructural limit/1.6 6.0volts.Thisstructural repairlimitsupportsthisapplication forCycle14IPCimplementation torepairbobbinindications greaterthan2.0voltsindependent ofRPCconfirmation oftheindication. | |||
Conservatively, anupperlimitof3.6voltswillbeusedtoassesstubeintegrity forthose Attachment 1toAEP:NRC:1166L Page9bobbinindications whichareabove2.0voltsbutdonothaveconfirming RPCcalls.Theconservatism ofthisrepairlimitisshownbytheEOC12(Summer1992)eddycurrentdata.Theoverallaveragevoltagegrowthwasdetermined tobeonly2.2%(oftheBOCvoltage), | |||
witha12%averagevoltagegrowthforindications lessthan1.0voltBOCanda1$averagevoltagegrowthforindications greaterthan0.75voltsattheBOC.Inaddition, theEOC12maximumobservedvoltageincreasewasfoundtobe0.49volts,andoccurredinatubeinitially lessthan1.0voltBOC.Theapplicability ofCycle13growthratesforCycle14operation willbeconfirmed priortoreturntoserviceofCookNuclearPlantUnit1.Similarlargestructural marginsareanticipated. | |||
Relativetotheexpectedleakageduringaccidentcondition | |||
: loadings, ithasbeenpreviously established thatapostulated mainsteamline breakoutsideofcontainment butupstreamofthemainsteamisolation valverepresents themostlimitingradiological condition relativetotheIPC.Insupportofimplementation oftheinterimpluggingcriteria, itwillbedetermined whetherthedistribution ofcrackindications atthetubesupportplateintersections attheendofCycle14areprojected tobesuchthatprimarytosecondary leakagewouldresultinsiteboundarydoseswithinasmallfractionofthe10CFR100guidelines. | |||
Aseparatecalculation hasdetermined thisallowable steamline breakleakagelimittobe12.6gpm.AlthoughnotrequiredbytheCookNuclearPlantdesignbasis,thiscalculation usestherecommended Iodine-131 transient spikingvaluesconsistent withNUREG-0800, andtheT/Sreactorcoolantsystemactivitylimitof1.0microcuriepergramdoseequivalent Iodine-131.Theprojected steamline breakleakageratecalculation methodology prescribed inSection3.3ofdraftNUREG-1477 willbeusedtocalculate EOC14leakage.Duetotherelatively lowvoltagegrowthratesatCookNuclearPlantUnit1andtherelatively smallnumberofindications affectedbytheIPC,steamline breakleakageprediction perdraftNUREG<<1477 isexpectedtobelessthantheacceptance limitof12.6gpminthefaultedloop.Application ofthecriteriarequirestheprojection ofpostulated steamline breakleakage,basedontheEOCvoltagedistribution. | |||
EOCvoltagedistribution isdeveloped usingEOC-13eddycurrentresultsandavoltagemeasurement uncertainty. | |||
Thedataindicates thatathreshold voltageof2.81voltswouldresultinthroughwall crackslongenoughtoleakatsteamline breakconditions. | |||
DraftNUREG-1477 requiresthatallindications towhichtheIPCareappliedmustbeincludedintheleakageprojection. | |||
TubepullresultsfromCookNuclearPlantUnit1indicatethattubewalldegradation ofgreaterthan40%throughwall wasdetectable eitherbythebobbinorRPCprobe.Thetubewithmaximumthroughwall penetration of56%(42%average)hadavoltageof2.02volts.Thisindication alsowasthelargestrecordedbobbinvoltagefromtheEOC12 Attachment 1toAEP:NRC:1166L Page10leakageof2.81volts,inclusion ofallIPCintersections intheleakagemodelisquiteconservative. | |||
Therefore, asimplementation ofthe2.0voltinterimpluggingcriteriaduringCycle14doesnotadversely affectsteamgenerator tubeintegrity andresultsinacceptable doseconsequences theproposedamendment doesnotresultinanyincreaseintheprobability orconsequences ofanaccidentpreviously evaluated withintheCookNuclearPlantUnit1FSAR.2)Theproposedlicenseamendment doesnotcreatethepossibility ofanewordifferent kindofaccidentfromanyaccidentpreviously evaluated. | |||
Implementation oftheproposedsteamgenerator tubeinterimpluggingcriteriadoesnotintroduce anysignificant changestotheplantdesignbasis.Useofthecriteriadoesnotprovideamechanism whichcouldresultinanaccidentoutsideoftheregionofthetubesupportplateelevations; noODSCCisoccurring outsidethethickness ofthetubesupportplates.Neitherasingleormultipletuberuptureeventwouldbeexpectedinasteamgenerator inwhichthepluggingcriteriahasbeen.applied(duringallplantconditions). | |||
Specifically, wewillcontinuetoimplement amaximumleakageratelimitof150gpd(0.1gpm)persteamgenerator tohelpprecludethepotential forexcessive leakageduringallplantconditions. | |||
TheCycle14T/Slimitsonprimarytosecondary leakageatoperating conditions isamaximumof0.4gpm(600gpd)forallsteamgenerators, or,amaximumof150gpdforanyonesteamgenerator. | |||
TheRG1.121criterion forestablishing operational leakageratelimitsthatrequireplantshutdownarebaseduponleak-before-break considerations todetectafreespancrackbeforepotential tuberuptureduringfaultedplantconditions. | |||
The150gpdlimitshouldprovideforleakagedetection andplantshutdownintheeventoftheoccurrence ofanunexpected singlecrackresulting inleakagethatisassociated withthelongestpermissible cracklength.RG1.121acceptance criteriaforestablishing operating leakagelimitsarebasedonleak-before-break considerations suchthatplantshutdownisinitiated iftheleakageassociated withthelongestpermissible crackisexceeded. | |||
Thelongestpermissible crackisthelengththatprovidesafactorofsafetyof1.43againstburstingatfaultedconditions maximumpressuredifferential. | |||
Avoltageamplitude of9.6voltsfortypicalODSCCcorresponds tomeetingthistubeburstrequirement atalower95%prediction limitontheburstcorrelation coupledwith95/95lowertolerance limit(LTL)materialproperties. | |||
Alternate crackmorphologies cancorrespond to9.6voltssothatauniquecracklengthisnotdefinedbytheburstpressureversusvoltagecorrelation. | |||
Consequently, typicalburstpressureversusthrough-wall cracklengthcorrelations areusedbelowtodefinethe"longestpermissible crack"forevaluating operating leakagelimits. | |||
~~ | ~~ | ||
(~~~ | (~~~Attachment 1toAEP:NRC:1166L Page11thatauniquecracklengthisnotdefinedbytheburstpressureversusvoltagecorrelation. | ||
Consequently, typicalburstpressureversusthrough-wall cracklengthcorrelations areusedbelowtodefinethe"longestpermissible crack"forevaluating operating leakagelimits.Thesinglethrough-wall cracklengthsthatresultintubeburstat1.43timesthesteamline breakpressuredifferential (1.43x2560psi-3660psi)andthesteamline breakpressuredifferential alone(2560psi)areapproximately 0.53inchand0.84inch,respectively. | |||
Aleakrateof150gpdwillprovidefordetection of0.42inchlongcracksatnominalleakratesand0.61inchlongcracksatthelower95%confidence levelleakrates.Sincetubeburstisprecluded duringnormaloperation duetotheproximity oftheTSPtothetubeandthepotential existsforthecrevicetobecomeuncovered duringsteamline breakconditions, theleakagefromthemaximumpermissible crackmustprecludetubeburstatsteamline breakconditions. | |||
Thus,the150gpdlimitprovidesforplantshutdownpriortoreachingcriticalcracklengthsforsteamline breakconditions. | |||
Additionally, thisleak-before-break evaluation assumesthattheentirecreviceareaisuncovered duringblowdown. | |||
Partialuncoverywillprovidebenefittot'eburstcapacityoftheintersection. | |||
3)Theproposedlicenseamendment doesnotinvolveasignificant reduction inmarginofsafety.Theuseofthevoltagebasedbobbinprobeinterimtubesupportplateelevation pluggingcriteriaatCookNuclearPlantUnit1isdemonstrated tomaintainsteamgenerator tubeintegrity commensurate withthecriteriaofRG1.121.RG1.121describes amethodacceptable totheNRCstaffformeetingGDCs14,15,31,and32byreducingtheprobability ortheconsequences ofsteamgenerator tuberupture.Thisisaccomplished bydetermining thelimitingconditions ofdegradation ofsteamgenerator tubing,asestablished byinservice inspection, forwhichtubeswithunacceptable crackingshouldberemovedfromservice.Uponimplementation ofthecriteria, evenundertheworstcaseconditions, theoccurrence ofODSCCatthetubesupportplateelevations isnotexpectedtoleadtoasteamgenerator tuberuptureeventduringnormalorfaultedplantconditions. | |||
TheEOC14distribution ofcrackindications att'etubesupportplateelevations willbeconfirmed toresultinacceptable primarytosecondary leakageduringallplantconditions andthatradiological consequences arenotadversely impacted. | |||
Inaddressing thecombinedeffectsofalossofcoolantaccident(LOCA)+safeshutdownearthquake (SSE)onthesteamgenerator component (asrequiredbyGDC2),ithasbeendetermined thattubecollapsemayoccurinthesteamgenerators atsomeplants.Thisisthecaseasthetubesupportplatesmaybecomedeformedasaresultoflateralloadsatthewedge | |||
~~ | ~~ | ||
Attachment 1toAEP:NRC:1166L Page12supportsattheperiphery oftheplateduetothecombinedeffectsoftheLOCArarefaction waveandSSEloadings. | |||
Then,theresulting pressuredifferential onthedeformedtubesmaycausesomeofthetubestocollapse. | |||
Therearetwoissuesassociated withsteamgenerator tubecollapse. | |||
First,thecollapseofsteamgenerator tubingreducestheRCSflowareathroughthetubes.Thereduction inflowareaincreases theresistance toflowofsteamfromthecoreduringaLOCAwhich,inturn,maypotentially increasePeakCladTemperature (PCT).Second,thereisapotential thatpartialthrough-wall cracksintubescouldprogresstothrough-wall cracksduringtubedeformation orcollapse. | |||
Consequently, sincetheleak-before-break methodology isapplicable totheCookNuclearPlantUnit1reactorcoolantlooppiping,theprobability ofbreaksintheprimarylooppipingissufficiently lowthattheyneednotbeconsidered inthestructural designoftheplant.ThelimitingLOCAeventbecomeseithertheaccumulator linebreakorthepressurizer surgelinebreak.LOCAloadsfortheprimarypipebreakswereusedtoboundtheCookNuclearPlantUnit1smallerbreaks.TheresultsoftheanalysisusingthelargerbreakinputsshowthattheLOCAloadswerefoundtobeofinsufficient magnitude toresultinsteamgenerator tubecollapseorsignificant deformation. | |||
Addressing RG1.83considerations, implementation ofthebobbinprobevoltagebasedinterimtubepluggingcriteriaof2.0voltsissupplemented byenhancededdycurrentinspection guidelines toprovideconsistency involtagenormalization, a1008eddycurrentinspection samplesizeatthetubesupportplateelevations perT/S,andRPCinspection requirements forthelargerindications leftinservicetocharacterize theprincipal degradation asODSCC.'Asnotedpreviously, implementation ofthetubesupportplateelevation pluggingcriteriawilldecreasethenumberoftubeswhichmustberepaired. | |||
Theinstallation ofsteamgenerator tubeplugsreducestheRCSflowmargin.Thus,implementation oftheinterimpluggingcriteriawillmaintainthemarginofflowthatwouldotherwise bereducedintheeventofincreased tubeplugging. | |||
Basedontheabove,itisconcluded thattheproposedlicenseamendment requestdoesnotresultinasignificant reduction inmarginwithrespecttoplantsafetyasdefinedintheFinalSafetyAnalysisReportoranyBasesoftheplantT/Ss. | |||
k~I}} | k~I}} | ||
Revision as of 08:13, 29 June 2018
| ML17331B235 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 02/15/1994 |
| From: | FITZPATRICK E INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG |
| To: | MURLEY T E NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML17331B236 | List: |
| References | |
| AEP:NRC:1166L, NUDOCS 9402240387 | |
| Download: ML17331B235 (24) | |
Text
LERATEDDI,UTIONDEMONS'ION SYSTEMREGULATORY INFORMATION DISTRIBUTION SYSTEM(RIDS)ACCESSION NBR:9402240387 DOC.DATE:
94/02/15NOTARIZED:
YESDOCKETFACIL:50-315 DonaldC.CookNuclearPowerPlant,Unit1,IndianaM05000315AUTH.NAMEAUTHORAFFILIATION FITZPATRICK,E.
IndianaMichiganPowerCo.(formerly Indiana6MichiganEleRECIP.NAME RECIPIENT AFFILIATION MURLEY,T.E.
DocumentControlBranch(Document ControlDesk)R
SUBJECT:
Application foramendtoLicenseDPR-58,incorporating
2.0 voltsteamgenerator
tubesupportplateinterimpluggingcriteriaforCycle14.DISTRIBUTION CODE:A001DCOPIESRECEIVED:LTR ENCLSIZETITLE:ORSubmittal:
GeneralDistribution NOTES:RECIPIENT IDCODE/NAME PD3-1LAHICKMAN,J INTERNALNRR/DE/EELB NRR/DRCH/HICB NRR/DSSA/SPLB NUDOCS-ABSTRACT OGC/HDS2EXTERNAL:
NRCPDRCOPIESLTTRENCL1122111111111011RECIPIENT IDCODE/NAME PD3-1PDNRR/DORS/OTS BNRR/DRPWNRR/DSSA/SRXB
-e/"BPBCBEGFI01NSICCOPIESLTTRENCL11111111101111DDDNOTETOALL"RIDS"RECIPIENTS:
DDPLEASEHELPUSTOREDUCEWASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMPl-37(EXT.20079)TOELIMINATE YOURNAMEFROMDISTRIBUTION LINISFORDOCUMENTS YOUDON'TNEED!TOTALNUMBEROFCOPIESREQUIRED:
LTTR16ENCL14 0414 IndianaNlchiganPowerCompanyP.O.Box16631Columbus, OH43216IAEP:NRC:1166L DonaldC.CookNuclearPlantUnit1DocketNo.50-315LicenseNo,DPR-58TECHNICAL SPECIFICATION CHANGESTOINCORPORATE
2.0 VOLTINTERIMSTEAMGENERATOR
TUBESUPPORTPLATEPLUGGINGCRITERION FORFUELCYCLE14U.S.NuclearRegulatory Commission DocumentControlDeskWashington, D.C.20555Attn:T.EDMurleyFebruary15,1994
DearDr.Murley:
Thisletteranditsattachments constitute anapplication foranexigentamendment totheTechnical Specifications (T/Ss)fortheDonaldC.CookNuclearPlantUnit1,Specifically, wearerequesting toincorporate a2.0voltsteamgenerator tubesupportplateinterimpluggingcriterion forFuelCycle14.Asdiscussed withyourstaffonFebruary9,1994,thereasonformakingtherequestonanexigentbasisisthatthechangeisassociated withsteamgenerator repairsduringthecurrentUnit1refueling outage.Therepairsarecurrently scheduled tobeginMarch6,1994.Therefore, werequestapprovalofthisamendment requestbyMarch4inordertoavoidoutagedelays.ByletterdatedDecember15,1993(AEP:NRC:1166H),
werequested similarsteamgenerator tubeinterimpluggingcriteriaT/Schanges.Thisletterdoesnotsupersede theprevioussubmittal.
Thechangesdifferfromourprevioussubmittal inthatthissubmittal incorporates a2.0voltcriterion versustheprevious1.0voltlimit.Theuppervoltagelimitfordisposition ofindications byrotatingpancakecoilinspection isalsochangedfrom3.1voltsto3.6volts.Additionally, predicted end-of-cycle leakageinthefaultedloopforapostulated steamline breakislimitedto12.6gpm,versus1.0gpm.Thisisbasedonaradiological analysisperformed inaccordance withtheStandardReviewPlan,including iodinespikingandT/Sreactorcoolantsystemactivitylimits.TheT/Schangesrequested inthissubmittal aresimilartoaDecember9,1993,requestmadebytheFarleyNuclearPlantUnit1.9402240387 940215PDRADOCK05000315I;.P.PDRgdOlI(I IIIpI Dr.T.E.Murley2AEP:NRC:1166L Asdiscussed withyourstaffonFebruary9,arotatingpancakecoilinspection willbeperformed foralltubeswithanindication above1.0volt,despitethechangeintheinterimpluggingcriteriato2.0volts.Itisanticipated thatthestandardbobbinprobe(0.720inches)willbetheprobeusedfortubepluggingdetermination inconjunction withtheinterimpluggingcriteria.
Ifasmallerbobbinprobeisused,itisourunderstanding thatitsusemustbesupported byarigorousstatistical analysis.
Ifthesmallerbobbinprobeistobeused,thedetailsofthestatistical analysiswillbethesubjectofseparatecorrespondence.
Asdiscussed inoursubmittal AEP:NRC:1166H, westatedourpositionregarding notremovingtubesduringthe1994refueling outage.Changingtheinterimpluggingcriteriafrom1.0to2.0voltsdoesnotchangethebasisforourposition.
Also,thatsubmittal providedanappendixentitled"NDEDataAcquisition andAnalysisGuidelines."
AlthoughthisappendixwaswrittenspecifictoanIPCof1.0volts,itisstillapplicable inthegeneralsensewithanIPCof2.0volts,andtherefore, perdiscussions withyourstaffofFebruary9,1994,willnotberevisedforthisletter.Attachment 1containsadescription oftheproposedT/Schangesaswellasthe10CFR50.92nosignificant hazardsevaluation.
Attachment 2containstheexistingT/Spagesmarkedtoreflectthechanges.Attachment 3containstheproposedrevisedT/Spages.Attachment 4containstheradiological analysisthatsupportsthe12.6gpmend-of-cycle leakagelimitdiscussed above.Webelievetheproposedchangeswillnotresultin(1)asignificant changeinthetypesofanyeffluentthatmaybereleasedoffsite,or(2)asignificant increaseinindividual orcumulative occupational radiation exposure.
TheseproposedchangeshavebeenreviewedbythePlantNuclearSafetyReviewCommittee andbytheNuclearSafetyandDesignReviewCommittee.
Incompliance withtherequirements of10CFR50.91(b)(l),
copiesofthisletteranditsattachments havebeentransmitted totheMichiganPublicServiceCommission andtotheMichiganDepartment ofPublicHealth.Thisletterissubmitted pursuantto10CFR50.30(b),
and,assuch,anoathstatement isattached.
Sincerely, EFE.E.Fitzpatrick VicePresident Dr.T.E.Murley3AEP:NRC:1166L drAttachments cc:A.A.BlindG.CharnoffJ.B.Martin-RegionIIINFEMSectionChiefNRCResidentInspector J.R.Padgett STATEOFOHIO)COUNTYOFFRANKLIN)
E.E.Fitzpatrick, beingdulysworn,deposesandsaysthatheistheVicePresident oflicenseeIndianaMichiganPowerCompany,thathehasreadtheforgoingTECHNICAL SPECIFICATION CHANGESTOINCORPORATE
2.0 VOLTINTERIMSTEAMGENERATOR
TUBESUPPORTPLATEPLUGGINGCRITERION FORFUELCYCLE14andknowsthecontentsthereof;andthatsaidcontentsaretruetothebestofhisknowledge andbelief.Subscribed andsworntobeforemethis/W~dayofNOTARYPUBLICRITAD.HILLSOTARYPUBLIC.STATOFOHIOaVCOhIh'IISSIOH EXPIRE-~X r4I/
ATTACHMENT 1TOAEP:NRC:1166L DESCRIPTION ANDJUSTIFICATION OFCHANGES10CFR50.92ANALYSISFORCHANGESTOTHEDONALDC.COOKNUCLEARPLANTUNIT1TECHNICAL SPECIFICATIONS Attachment 1toAEP:NRC:1166L Page1I.INTRODUCTION Thisamendment requestproposesachangetoT/S4.4.5(SteamGenerators) toincorporate arevisedcriterion forsteamgenerator tubesupportplateinterimpluggingcriterion (IPC).Thechangesallowsteamgenerator tubeswithindications lessthanorequalto2.0voltstoremaininservice,regardless ofdepthoftubewallpenetration, ifasaresult,theprojected end-of-cycle (EOC)distribution ofcrackindications isverifiedtoresultinprimary-to-secondary leakagelessthan12.6gpminthefaultedloopduringapostulated steamline breakevent.Indications greaterthan2.0voltsbutlessthanorequalto3.6voltscanremaininserviceifarotatingpancakecoilprobe(RPC)inspection doesnotdetectdegradation.
Theamendment requestisspecifictoFuelCycle14only.Thepurposeoftheamendment istoreducethenumberoftubesrequiredtobeplugged.ThishasbenefitsbothfromanALARAperspective aswellastheperspective ofmaximizing RCSflowmargin.A1.0voltIPCwasgrantedforCookNuclearPlantUnit1,viaT/SAmendment 166,forthepreviousfuelcycle(Cycle13).ByletterdatedDecember15,1993(AEP:NRC:1166H),
werequested similarsteamgenerator tubeinterimpluggingcriteriaT/SchangesforCycle14.Thisletterdoesnotsupersede theprevioussubmittal.
Thechangesdifferfromourprevioussubmittal inthatthissubmittal incorporates a2.0voltcriteriaversustheprevious.1.0voltlimit.TheuppervoltagelimitforRPCconfirmation ischangedfrom3.1voltsto3.6volts.Additionally, predicted end-of-cycle leakageinthefaultedloopforapostulated steamline breakislimitedto12.6gpm,versus1.0gpm.Thisisbasedon'aradiological analysisperformed inaccordance withtheStandardReviewPlan,including iodinespikingandT/Slimitsonreactorcoolantsystemactivity.
(Theprevioussubmittal didnotincludetheeffectsofiodinespikingonthedoseanalysisandassumedreactorcoolantactivitycorresponding to1%failedfuel.)TheT/Schangesrequested inthissubmittal aresimilartoaDecember9,1993,requestmadebytheFarleyNuclearPlantUnit1.Asdiscussed withyourstaffonFebruary9,anRPCinspection willbeperformed foralltubeswithanindication above1.0volt,despitethechangeintheinterimpluggingcriteriafrom1.0voltto2.0volts.Itisanticipated thatthestandardbobbinprobe(0.720inches)willbetheprobeusedfortubepluggingdetermination inconjunction withtheinterimpluggingcriteria.
Ifasmallerbobbinprobeisused,itisourunderstanding thatitsusemustbesupported byarigorousstatistical analysis.
Ifthesmallerbobbinprobeistobeused,thedetailsofthestatistical analysiswillbethesubjectofseparatecorrespondence.
Attachment 1toAEP:NRC:1166L Page2Our1.0voltIPCsubmittal (AEP:NRC:1166H) providedanappendixentitled"NDEDataAcquisition andAnalysisGuidelines."
AlthoughthisappendixwaswrittenspecifictoanIPCof1.0volt,itisstillapplicable inthegeneralsensewithanIPCof2.0volts,andtherefore, perdiscussions withyourstaffofFebruary9,1994,willnotberevisedforthissubmittal.
Assessment ofIPCMethodolo Anassessment ofthemethodology described inWCAP-13187, Revision0willbeconducted fortheIPC.Itwilladdressdiscrepancies betweenpredicted andactualEOCvoltagedistributions.
Theassessment willinclude:a.EOC12voltagedistribution
-indications foundduringtheinspection regardless ofRPCverification results.b.Cycle12growthrate(i.e.frombeginning ofcycle(BOC)12toEOC12).c~EOC12repairedindications voltagedistribution distribution ofindications presented in(a)abovethatwererepaired(ifpluggedorsleeved).
d.Voltagedistribution forindications leftinserviceattheBOC13regardless ofRPCconfirmation
-obtainedfrom(a)and(c)above.e.Voltagedistribution forindications leftinserviceattheBOC13thatwereconfirmed byRPCtobecrack-like ornotRPCinspected.
Non-destructive examination uncertainty distribution usedinpredicting theEOC13voltagedistribution.
goProjected EOC13voltagedistribution usingthemethodology inWCAP-13187, Revision0.h.ActualEOC13voltagedistribution
-indications foundduringtheinspection regardless ofRPCconfirmation.
Cycle13growthrate(i.e.fromBOC13toEOC13).EOC13repairedindications voltagedistribution distribution ofindications presented in(h)abovethatwererepaired(i.e.pluggedorsleeved).
Attachment 1toAEP:NRC:1166L Page3k.Voltagedistribution forindications leftinserviceattheBOC14regardless ofRPCconfirmation
-obtainedfrom(h)and(j)above.1.Voltagedistribution forindications leftinserviceattheBOC14thatwereconfirmed byRPCtobecrack-like ornotRPCinspected.
m.Nondestructive examination uncertainty distribution usedinpredicting theEOC14voltagedistribution.
n.Projected EOC14voltagedistribution usingthemethodology inWCAP-13187, Revision0.Thetotalassessment, (a)through(n)willbesubmitted approximately 10weeksfromcompletion ofsteamgenerator inspections.
However,perT/Srequirements thesteamline breakleakageanalysisperformed underT/S4.4.5.4.a.10 willbereportedtotheNRCStaffpriortorestartforFuelCycle14.II.SCTIONOFTHECHANGESTheproposedchangesarethosenecessary toincorporate a2.0voltIPCforCookNuclearPlantUnit1FuelCycle14.Thespecificchangesareasfollows:1.TS4452d4455e3462cBases3445Bases34462Reference toFuelCycle13fortheIPCischangedtoFuelCycle14.Thedefinition ofIPCismodifiedsuchthatsteamgenerator tubeswithindications lessthanorequalto2.0volts(vs.1.0volt)canremaininservice,regardless ofdepthoftubewallpenetration, ifasaresult,theprojected end-of-cycle distribution ofcrackindications isverifiedtoresultinprimary-to-secondary leakagelessthan12.6gpm(vs.1.0gpm)inthefaultedloopduringapostulated steamline breakevent.Indications greaterthan2.0voltsbutless'hanorequalto3.6volts(vs.1.0voltand4.0volts)canremaininserviceifaRPCinspection doesnotdetectdegradation.
Attachment 1toAEP:NRC:1166L Page4Theend-of-cycle primarytosecondary leakagemustbelessthan12.6gpminthefaultedloop,versusthepresent1.0gpm,forapostulated steamline breakevent.Theleakageassumedintheaccidentanalysisischangedfrom120gpmto12.6gpm(fortheCycle14IPConly).III.10CFR5092EVALUATION BACKGROUND CookNuclearPlantUnit1T/SAmendment 166permitted theimplementation ofa1.0voltsteamgenerator tubeinterimpluggingcriteria(IPC)forthe13thoperating cycleoftheCookNuclearPlantUnit1steamgenerators.
Thislicenseamendment wasapplicable onlyforthepreviouscycle(Cycle13),andrequiredtherepairofflaw-like bobbinindications above1.0volt.BasedupontubepullresultsfromCookNuclearPlantUnit1andotherplantsgatheredsincethestartofCycle13,weareproposing useofa2.0voltinterimrepaircriterion fortheupcomingCycle14.DESCRIPTION OFTHEIPCREQUESTAsrequiredby10CFR50.91(a)(l),ananalysisisprovidedtodemonstrate thattheproposedlicenseamendment toimplement aninterimtubepluggingcriteriaforthetubesupportplateelevation outerdiameterstresscorrosion cracking(ODSCC)occurring intheCookNuclearPlantUnit1steamgenerators involvesanosignificant hazardsconsideration.
TheIPCutilizescorrelations betweeneddycurrentbobbinprobesignalamplitude (voltage) andtubeburstandleakagecapability.
Thepluggingcriteriaisbasedontestingoflaboratory inducedODSCCspecimens, andextensive examination ofpulledtubesfromoperating steamgenerators (industry wideincluding 3tubesrepresenting 6intersections fromtheCookNuclearPlantUnit1steamgenerators.)
Theinterimpluggingcriteriacanbedescribed bythefollowing elements:
A1008bobbincoilinspection ofhotlegtubesupportplateintersections andcoldlegintersections downtothelowestcoldlegtubesupportplatewithknownODSCCindications willbeperformed.
2.Flaw-like signalsadjacenttothetubesupportplateswithbobbinvoltageslessthanorequalto2.0voltswil'1beallowedtoremaininservice.
Attachment 1toAEP:NRC:1166L Page53.Flaw-like signalsadjacenttothetubesupportplatewithabobbinvoltageofgreaterthan2.0voltswillberepairedexceptasnotedinItem4.4.Flaw-like signalsadjacenttothetubesupportplatewithabobbinvoltagegreaterthan2.0voltsbutlessthanorequalto3.6voltsmayremaininserviceifRPCinspection doesnotdetectaflaw.Flawindications withabobbinvoltagegreaterthan3.6voltswillberepaired.
5.Aspartofasampleinspection programtohelpensurethatadditional degradation modesarenotoccurring, allflawindications withbobbinvoltagesgreaterthan1.0voltbutlessthanorequalto2.0voltswillbeinspected byRPC.6.Anend-of-cycle voltagedistribution willbeestablished basedupontheend-of-Cycle 13eddycurrentdata.Baseduponthisdistribution, postulated steamline breakleakagewillbeestimated basedontheguidanceofdraftNUREG1477.Projected leakagemustremainbelow12.6gpminthefaultedloopinorderforoffsitedoseestimates toremainwithin10%ofthe10CFR100guidelines.
Asprescribed indraftNUREG-1477, anevaluation ofprimarytosecondary leakage(andsubsequently offsitedose)isrequiredforallplantsimplementing theinterimpluggingcriteria(IPC).PerdraftNUREG-1477, allbobbinindications areincludedinthesteamline breakleakageanalysesalongwiththeconsideration ofprobability ofdetection (POD).Iftheprojected leakageexceeds12.6gpminthefaultedloopduringapostulated steamline breakevent,thenumberofindications inwhichtheinterimpluggingcriteriaareappliedisreducedthroughtuberepairuntiltheprimarytosecondary leakagelimitsaresatisfied.
EVALUATION TubeDegradation Characterization Ingeneral,thedegradation morphology occurring atthetubesupportplateintersections atplantsintheU.S.canbedescribed asaxiallyorientedODSCC.Thedegradation morphology atCookNuclearPlantUnit1isentirelycompatible withtheoverallindustrydatabase.SteamGenerator TubeIntegrity Inthedevelopment ofaninterimpluggingcriteriaforCookNuclearPlantUnit1,Regulatory Guide(RG)1.121,"BasesforPluggingDegradedPWRSteamGenerator Tubes"andRG1.83"Inservice Inspection ofPWRSteamGenerator Tubes"areusedasthebasesfordetermining thatsteam Attachment 1toAEP:NRC:1166L Page6generator tubeintegrity considerations aremaintained withinacceptable limits.RG1.121describes amethodacceptable totheNRCstaffformeetingGeneralDesignCriteria14,15,31,and32byreducingtheprobability andconsequences ofsteamgenerator tuberupturethroughdetermining thelimitingsafeconditions oftubewalldegradation beyondwhichtubeswithunacceptable
- cracking, asestablished byinservice inspection, shouldberemovedfromservicebyplugging.
Thisregulatory guideusessafetyfactorsonloadsfortubeburstthatareconsistent withtherequirements ofSectionIIIoftheASMECode.Forthetubesupportplateelevation degradation occurring intheCookNuclearPlantUnit1steamgenerators, tubeburstcriteriaareinherently satisfied duringnormaloperating conditions bythepresenceofthetubesupportplate.Thepresenceofthetubesupportplateenhancestheintegrity ofthedegradedtubesinthatregionbyprecluding tubedeformation beyondthediameterofthedrilledhole,thusprecluding tubeburst.Conservatively, nocreditistakeninthedevelopment ofthepluggingcriteriaforthepresenceofthetubesupportplateduringaccidentconditions.
Basedontheexistingdatabasefor7/8inchtubing,bursttestingshowsthatthesafetyrequirements fortubeburstmarginsduringaccidentcondition loadingscanbesatisfied withendofcyclebobbincoilsignalamplitudes lessthan9.6volts,regardless ofthedepthoftubewallpenetration ofthecracking.
Uponimplementation ofthepluggingcriteria, tubeleakageconsiderations mustalsobeaddressed.
Itmustbedetermined thatthecrackswillnotleakexcessively duringallplantconditions.
Forthe2.0voltinterimtubepluggingcriteriadeveloped fortheCookNuclearPlantUnit1steamgenerator tubes,noleakageisanticipated duringnormaloperating conditions evenwiththepresenceofpotentially throughwall cracks.Noleakageduringnormaloperating conditions hasbeenobservedinthefieldforcrackindications withsignalamplitudes upto7.7volts(3/4inchtubes).Voltagecorrelation to7/8inchtubingsizewouldresultinanexpectedvoltageofabout10volts.Noprimarytosecondary leakageatthetubesupportplates(TSP)hasbeendetectedinU.S.plants.Relativetotheexpectedleakageduringaccidentcondition
- loadings, thelimitingeventwithrespecttodifferential pressureexperienced acrosstheSGtubesisapostulated steamline breakevent.For7/8inchtubing,pulledtubedatasupportsnoleakageupto2.81volts,andlowprobability ofleakagebetween2.81and6.0volts,forbothpulledtubesandmodelboilerspecimens attheboundingsteamline breakpressuredifferential of2560psi.Steamline breakprimarytosecondary leakagewillbecalculated asprescribed inSection3.3ofdraftNUREG-1477 (usingaprimary-to-secondary pressuredifferential of2560psid)onceEOC13eddycurrentdataisreduced.Thiscalculated leakagemustbeshowntobelessthan12.6gpminthefaultedloop.
~~~~~Attachment 1toAEP;NRC:1166L Page7Additional Considerations Theproposedamendment wouldprecludeoccupational radiation exposurethatwouldotherwise beincurredbypersonnel involvedintubepluggingorrepairoperations.
Byreducingnon-essential tubeplugging, theproposedamendment wouldminimizethelossofmargininthereactorcoolantflowthroughthesteamgenerator inLOCAanalyses.
Theproposedamendment wouldavoidlossofmargininreactorcoolantsystemflowand,therefore, assistindemonstrating thatminimumflowratesaremaintained inexcessofthatrequiredforoperation atfullpower.Reduction intheamountoftuberepairrequiredcanreducethelengthofplantoutagesandreducethetimethatthesteamgenerator isopentothecontainment environment duringanoutage.The1008eddycurrentbobbinprobeinspection associated withimplementation oftheIPCwillhelptoidentifynewareasofconcernwhichmayarisebyproviding alevelofinservice inspection whichisfarinexcessoftheT/Srequirements utilizing the40$depth-based plugginglimitforacceptable tubewalldegradation.
SIGNIFICANT HAZARDSANALYSISInaccordance withthethreefactortestof10CFR50,92(c),
implementation oftheproposedlicenseamendment isanalyzedusingthefollowing standards andfoundnotto1)involveasignificant increaseintheprobability orconsequences ofanaccidentpreviously evaluated; 2)createthepossibility ofanewordifferent kindofaccidentfromanyaccidentpreviously evaluated; or3)involveasignificant reduction inmarginofsafety.Conformance oftheproposedamendment tothestandards foradetermination ofnosignificant hazardsasdefinedin10CFR50.92(threefactortest)isshowninthefollowing:
1)Operation oftheDonaldC.CookNuclearPlantUnit1inaccordance withtheproposedlicenseamendment doesnotinvolveasignificant increaseintheprobability orconsequences ofanaccidentpreviously evaluated.
Testingofmodelboilerspecimens forfreespantubing(notubesupportplaterestraint) atroomtemperature conditions showburstpressures inexcessof5000psiforindications ofouterdiameterstresscorrosion crackingwithvoltagemeasurements ashighas19volts.Bursttestingperformed onpulledtubesfromCookNuclearPlantUnit1withuptoa2.02voltindication showsmeasuredburstpressureinexcessof10,000psiatroomtemperature, Bursttestingperformed onpulledtubesfromotherplantswithupto7.5voltindications showburstpressures inexcessof6,300psiatroomtemperatures.
Correcting fortheeffectsoftemperature onmaterialproperties andminimumstrengthlevels(asthebursttestingwasdoneatroomtemperature),
tubeburstcapability significantly exceedsthesafetyfactorrequirements ofRG1.121.Asstatedearlier,tubeburstcriteriaareinherently satisfied duringnormaloperating conditions duetotheproximity ofthetubesupportplate.Testdataindicates thattubeburstcannotoccurwithinthetubesupport Attachment 1toAEP:NRC:1166L Page8plate,evenfortubeswhichhave100%throughwall electric-discharge machined(EDM)notches0.75inchlong,providedthatthetubesupportplateisadjacenttothenotchedarea.Sincetubetotubesupportplateproximity precludes tubeburstduringnormaloperating conditions, useofthecriteriamustretaintubeintegrity characteristics whichmaintains theR.G.1.121marginofsafetyof1.43timestheboundingfaultedcondition (steamline break)pressuredifferential.
Duringapostulated mainsteamline break,theTSPhasthepotential todeflectduringblowdown, therebyuncovering theintersection.
Basedontheexistingdatabase,theRG1.121criterion requiring maintenance ofasafetyfactorof1.43timesthesteamline breakpressuredifferential ontubeburstissatisfied by7/8inchdiametertubingwithbobbincoilindications withsignalamplitudes lessthan9.6volts,regardless oftheindicated depthmeasurement.
A2.0voltpluggingcriteriacomparesfavorably withthe9.6voltstructural limitconsidering thepreviously calculated growthratesforODSCCwithintheCookNuclearPlantUnit1steamgenerators.
Considering avoltagegrowthcomponent of0,8volts(40%voltagegrowthbasedon2.0voltsBOC)andanNDEuncertainty of0.40volts(20%voltageuncertainty basedon2.0voltsBOC),whenaddedtotheBOCinterimpluggingcriteriaof2.0voltsresultsinaboundingEOCvoltageofapproximately 3.2voltsforCycle14operation.
A6.4voltsafetymarginexists(9.6structural limit-3.2voltEOC-6.4voltmargin).Forthevoltage/burst correlation, theEOCstructural limitissupported byavoltageof9.6volts.Usingthisstructural limitof9.6volts,abeginning ofcycle(BOC)maximumallowable repairlimitcanbeestablished usingtheguidanceofRG1.121.TheBOCmaximumallowable repairlimitshouldnotpermittheexistence ofEOCindications whichexceedthe9.6voltstructural limit.ByaddingNDEuncertainty allowances andanallowance forcrackgrowthtotherepairlimit,thestructural limitcanbevalidated.
PreviousIPCsubmittals haveestablished theconservative NDEuncertainty limitof20$oftheBOCrepairlimit.Forconsistency, a408voltagegrowthallowance totheBOCrepairlimitisalsoincluded.
Thisallowance isextremely conservative forCookNuclearPlantUnit1.Therefore, themaximumallowable BOCrepairlimit(RL)basedonthestructural limitof9.6voltscanberepresented bytheexpression:
RL+(0.2xRL)+(0.4xRL)-9.6volts,or,themaximumallowable BOCrepairlimit(RL)canbeexpressed as,RL9.6voltstructural limit/1.6 6.0volts.Thisstructural repairlimitsupportsthisapplication forCycle14IPCimplementation torepairbobbinindications greaterthan2.0voltsindependent ofRPCconfirmation oftheindication.
Conservatively, anupperlimitof3.6voltswillbeusedtoassesstubeintegrity forthose Attachment 1toAEP:NRC:1166L Page9bobbinindications whichareabove2.0voltsbutdonothaveconfirming RPCcalls.Theconservatism ofthisrepairlimitisshownbytheEOC12(Summer1992)eddycurrentdata.Theoverallaveragevoltagegrowthwasdetermined tobeonly2.2%(oftheBOCvoltage),
witha12%averagevoltagegrowthforindications lessthan1.0voltBOCanda1$averagevoltagegrowthforindications greaterthan0.75voltsattheBOC.Inaddition, theEOC12maximumobservedvoltageincreasewasfoundtobe0.49volts,andoccurredinatubeinitially lessthan1.0voltBOC.Theapplicability ofCycle13growthratesforCycle14operation willbeconfirmed priortoreturntoserviceofCookNuclearPlantUnit1.Similarlargestructural marginsareanticipated.
Relativetotheexpectedleakageduringaccidentcondition
- loadings, ithasbeenpreviously established thatapostulated mainsteamline breakoutsideofcontainment butupstreamofthemainsteamisolation valverepresents themostlimitingradiological condition relativetotheIPC.Insupportofimplementation oftheinterimpluggingcriteria, itwillbedetermined whetherthedistribution ofcrackindications atthetubesupportplateintersections attheendofCycle14areprojected tobesuchthatprimarytosecondary leakagewouldresultinsiteboundarydoseswithinasmallfractionofthe10CFR100guidelines.
Aseparatecalculation hasdetermined thisallowable steamline breakleakagelimittobe12.6gpm.AlthoughnotrequiredbytheCookNuclearPlantdesignbasis,thiscalculation usestherecommended Iodine-131 transient spikingvaluesconsistent withNUREG-0800, andtheT/Sreactorcoolantsystemactivitylimitof1.0microcuriepergramdoseequivalent Iodine-131.Theprojected steamline breakleakageratecalculation methodology prescribed inSection3.3ofdraftNUREG-1477 willbeusedtocalculate EOC14leakage.Duetotherelatively lowvoltagegrowthratesatCookNuclearPlantUnit1andtherelatively smallnumberofindications affectedbytheIPC,steamline breakleakageprediction perdraftNUREG<<1477 isexpectedtobelessthantheacceptance limitof12.6gpminthefaultedloop.Application ofthecriteriarequirestheprojection ofpostulated steamline breakleakage,basedontheEOCvoltagedistribution.
EOCvoltagedistribution isdeveloped usingEOC-13eddycurrentresultsandavoltagemeasurement uncertainty.
Thedataindicates thatathreshold voltageof2.81voltswouldresultinthroughwall crackslongenoughtoleakatsteamline breakconditions.
DraftNUREG-1477 requiresthatallindications towhichtheIPCareappliedmustbeincludedintheleakageprojection.
TubepullresultsfromCookNuclearPlantUnit1indicatethattubewalldegradation ofgreaterthan40%throughwall wasdetectable eitherbythebobbinorRPCprobe.Thetubewithmaximumthroughwall penetration of56%(42%average)hadavoltageof2.02volts.Thisindication alsowasthelargestrecordedbobbinvoltagefromtheEOC12 Attachment 1toAEP:NRC:1166L Page10leakageof2.81volts,inclusion ofallIPCintersections intheleakagemodelisquiteconservative.
Therefore, asimplementation ofthe2.0voltinterimpluggingcriteriaduringCycle14doesnotadversely affectsteamgenerator tubeintegrity andresultsinacceptable doseconsequences theproposedamendment doesnotresultinanyincreaseintheprobability orconsequences ofanaccidentpreviously evaluated withintheCookNuclearPlantUnit1FSAR.2)Theproposedlicenseamendment doesnotcreatethepossibility ofanewordifferent kindofaccidentfromanyaccidentpreviously evaluated.
Implementation oftheproposedsteamgenerator tubeinterimpluggingcriteriadoesnotintroduce anysignificant changestotheplantdesignbasis.Useofthecriteriadoesnotprovideamechanism whichcouldresultinanaccidentoutsideoftheregionofthetubesupportplateelevations; noODSCCisoccurring outsidethethickness ofthetubesupportplates.Neitherasingleormultipletuberuptureeventwouldbeexpectedinasteamgenerator inwhichthepluggingcriteriahasbeen.applied(duringallplantconditions).
Specifically, wewillcontinuetoimplement amaximumleakageratelimitof150gpd(0.1gpm)persteamgenerator tohelpprecludethepotential forexcessive leakageduringallplantconditions.
TheCycle14T/Slimitsonprimarytosecondary leakageatoperating conditions isamaximumof0.4gpm(600gpd)forallsteamgenerators, or,amaximumof150gpdforanyonesteamgenerator.
TheRG1.121criterion forestablishing operational leakageratelimitsthatrequireplantshutdownarebaseduponleak-before-break considerations todetectafreespancrackbeforepotential tuberuptureduringfaultedplantconditions.
The150gpdlimitshouldprovideforleakagedetection andplantshutdownintheeventoftheoccurrence ofanunexpected singlecrackresulting inleakagethatisassociated withthelongestpermissible cracklength.RG1.121acceptance criteriaforestablishing operating leakagelimitsarebasedonleak-before-break considerations suchthatplantshutdownisinitiated iftheleakageassociated withthelongestpermissible crackisexceeded.
Thelongestpermissible crackisthelengththatprovidesafactorofsafetyof1.43againstburstingatfaultedconditions maximumpressuredifferential.
Avoltageamplitude of9.6voltsfortypicalODSCCcorresponds tomeetingthistubeburstrequirement atalower95%prediction limitontheburstcorrelation coupledwith95/95lowertolerance limit(LTL)materialproperties.
Alternate crackmorphologies cancorrespond to9.6voltssothatauniquecracklengthisnotdefinedbytheburstpressureversusvoltagecorrelation.
Consequently, typicalburstpressureversusthrough-wall cracklengthcorrelations areusedbelowtodefinethe"longestpermissible crack"forevaluating operating leakagelimits.
~~
(~~~Attachment 1toAEP:NRC:1166L Page11thatauniquecracklengthisnotdefinedbytheburstpressureversusvoltagecorrelation.
Consequently, typicalburstpressureversusthrough-wall cracklengthcorrelations areusedbelowtodefinethe"longestpermissible crack"forevaluating operating leakagelimits.Thesinglethrough-wall cracklengthsthatresultintubeburstat1.43timesthesteamline breakpressuredifferential (1.43x2560psi-3660psi)andthesteamline breakpressuredifferential alone(2560psi)areapproximately 0.53inchand0.84inch,respectively.
Aleakrateof150gpdwillprovidefordetection of0.42inchlongcracksatnominalleakratesand0.61inchlongcracksatthelower95%confidence levelleakrates.Sincetubeburstisprecluded duringnormaloperation duetotheproximity oftheTSPtothetubeandthepotential existsforthecrevicetobecomeuncovered duringsteamline breakconditions, theleakagefromthemaximumpermissible crackmustprecludetubeburstatsteamline breakconditions.
Thus,the150gpdlimitprovidesforplantshutdownpriortoreachingcriticalcracklengthsforsteamline breakconditions.
Additionally, thisleak-before-break evaluation assumesthattheentirecreviceareaisuncovered duringblowdown.
Partialuncoverywillprovidebenefittot'eburstcapacityoftheintersection.
3)Theproposedlicenseamendment doesnotinvolveasignificant reduction inmarginofsafety.Theuseofthevoltagebasedbobbinprobeinterimtubesupportplateelevation pluggingcriteriaatCookNuclearPlantUnit1isdemonstrated tomaintainsteamgenerator tubeintegrity commensurate withthecriteriaofRG1.121.RG1.121describes amethodacceptable totheNRCstaffformeetingGDCs14,15,31,and32byreducingtheprobability ortheconsequences ofsteamgenerator tuberupture.Thisisaccomplished bydetermining thelimitingconditions ofdegradation ofsteamgenerator tubing,asestablished byinservice inspection, forwhichtubeswithunacceptable crackingshouldberemovedfromservice.Uponimplementation ofthecriteria, evenundertheworstcaseconditions, theoccurrence ofODSCCatthetubesupportplateelevations isnotexpectedtoleadtoasteamgenerator tuberuptureeventduringnormalorfaultedplantconditions.
TheEOC14distribution ofcrackindications att'etubesupportplateelevations willbeconfirmed toresultinacceptable primarytosecondary leakageduringallplantconditions andthatradiological consequences arenotadversely impacted.
Inaddressing thecombinedeffectsofalossofcoolantaccident(LOCA)+safeshutdownearthquake (SSE)onthesteamgenerator component (asrequiredbyGDC2),ithasbeendetermined thattubecollapsemayoccurinthesteamgenerators atsomeplants.Thisisthecaseasthetubesupportplatesmaybecomedeformedasaresultoflateralloadsatthewedge
~~
Attachment 1toAEP:NRC:1166L Page12supportsattheperiphery oftheplateduetothecombinedeffectsoftheLOCArarefaction waveandSSEloadings.
Then,theresulting pressuredifferential onthedeformedtubesmaycausesomeofthetubestocollapse.
Therearetwoissuesassociated withsteamgenerator tubecollapse.
First,thecollapseofsteamgenerator tubingreducestheRCSflowareathroughthetubes.Thereduction inflowareaincreases theresistance toflowofsteamfromthecoreduringaLOCAwhich,inturn,maypotentially increasePeakCladTemperature (PCT).Second,thereisapotential thatpartialthrough-wall cracksintubescouldprogresstothrough-wall cracksduringtubedeformation orcollapse.
Consequently, sincetheleak-before-break methodology isapplicable totheCookNuclearPlantUnit1reactorcoolantlooppiping,theprobability ofbreaksintheprimarylooppipingissufficiently lowthattheyneednotbeconsidered inthestructural designoftheplant.ThelimitingLOCAeventbecomeseithertheaccumulator linebreakorthepressurizer surgelinebreak.LOCAloadsfortheprimarypipebreakswereusedtoboundtheCookNuclearPlantUnit1smallerbreaks.TheresultsoftheanalysisusingthelargerbreakinputsshowthattheLOCAloadswerefoundtobeofinsufficient magnitude toresultinsteamgenerator tubecollapseorsignificant deformation.
Addressing RG1.83considerations, implementation ofthebobbinprobevoltagebasedinterimtubepluggingcriteriaof2.0voltsissupplemented byenhancededdycurrentinspection guidelines toprovideconsistency involtagenormalization, a1008eddycurrentinspection samplesizeatthetubesupportplateelevations perT/S,andRPCinspection requirements forthelargerindications leftinservicetocharacterize theprincipal degradation asODSCC.'Asnotedpreviously, implementation ofthetubesupportplateelevation pluggingcriteriawilldecreasethenumberoftubeswhichmustberepaired.
Theinstallation ofsteamgenerator tubeplugsreducestheRCSflowmargin.Thus,implementation oftheinterimpluggingcriteriawillmaintainthemarginofflowthatwouldotherwise bereducedintheeventofincreased tubeplugging.
Basedontheabove,itisconcluded thattheproposedlicenseamendment requestdoesnotresultinasignificant reduction inmarginwithrespecttoplantsafetyasdefinedintheFinalSafetyAnalysisReportoranyBasesoftheplantT/Ss.
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