ML17331B238
| ML17331B238 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 02/15/1994 |
| From: | FITZPATRICK E INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML17331B239 | List: |
| References | |
| AEP:NRC:1166K, NUDOCS 9402250130 | |
| Download: ML17331B238 (16) | |
Text
.-,ACCELERATEDDISf/'TIONDEMONSATIONSYSTEMREGULATORYINFORMATIONDISTRIBUTIONSYSTEM(RIDS)ACCESSIONNBR:9402250130DOC.DATE:94/02/15NOTARIZED:YESDOCKETFACIL:50-315DonaldC.CookNuclearPowerPlant,Unit1,IndianaM05000315AUTH.NAMEAUTHORAFFILIATIONFITZPATRICK,E.IndianaMichiganPowerCo.(formerlyIndiana6MichiganEleRECIP.NAMERECIPIENTAFFILIATIONDocumentControlBranch(DocumentControlDesk)R
SUBJECT:
ApplicationforexigentamendtolicenseDPR-58,revisingTSI4.4.5,"SGs"toincorporateacceptancecriterionforSGtubedegradationintubesheetregionknownasF*.WestinghuseDreptsWCAP-139706WCAP-13971encl.WCAP-13970withheld.SDISTRIBUTIONCODE:AP01DCOPIESRECEIVED:LTRENCLSIZE:TITLE:ProprietaryReviewDistribution-PreOperatingLicense6OperatingR/NOTES:ghJCIPP~31'IlA>P4ICA'Pl3$40-RECIPIENTIDCODE/NAMEPD3-1LAHICKMAN,JINTERNAL:QD~OREGFILE01EXTERNALNRCPDRCOPIESLTTRENCL11331i1110IhrP)RECIPIENTIDCODE/NAMEPD3-,1PDOGC/HDS2COPIESLTTRENCL1110DDDNOTETOALL"RIDS"RECIPIENTS:PLEASEHELPUSlOREDUCEWASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMPl-37(EXT.20079)TOELIMINATEYOURNAMEFROMDISTRIBUTIONLISTSFORDOCUMENTSYOUDON'TNEED!TOTALNUMBEROFCOPIESREQUIRED:LTTR9ENCL7DD
/*0I'1e~FjfIIcI IndianainlchlganPo'warCompanyP.O.Box16631Coiumbus,OH43216AEP:NRC:1166KDonaldC.CookNuclearPlantUnit1DocketNo.50-315LicenseNo.DPR-58TECHNICALSPECIFICATIONCHANGESTOINCORPORATEMSTEAMGENERATORTUBEPLUGGINGCRITERIONU.S.NuclearRegulatoryCommissionDocumentControlDeskWashington,D.C.20555Attn:T.E.MurleyFebruary15,1994
DearDr.Murley:
ThisletteranditsattachmentsconstituteanapplicationforanexigentamendmenttotheTechnicalSpecifications(T/Ss)forDonaldC.CookNuclearPlantUnit1.Specifically,wearerequestingachangetoT/S4.4.5(SteamGenerators)toincorporateanacceptancecriterionforsteamgeneratortubedegradationinthetubesheetregionknownasM.Thiscriterionhasbeenlicensedandsuccessfullyimplementedatanumberofoperatingplants.AsdiscussedwithyourstaffonFebruary9,1994,thereasonforrequestingthisonanexigentbasisisthatthechangeisassociatedwithsteamgeneratorrepairsduringthecurrentUnit1refuelingoutage.TherepairsarecurrentlyscheduledtobeginMarch6,1994.Therefore,werequestapprovalofthisamendmentrequestbyMarch4,inordertoavoidoutagedelays.Attachment1containsadescriptionoftheproposedT/Schangesaswellasthe10CFR50.92nosignificanthazardsevaluation.Attachment2containstheexistingT/Spagesmarkedtoreflectthechanges.Attachment3containstheproposedrevisedT/Spages.Attachment4containsWestinghouseElectricCorporation'sreportWCAP-13970,entitled"WTubePluggingCriterionforTubeswithDegradationintheTubesheetRollExpansionRegionofCookNuclearPlantUnit1SteamGenerators."Thisreportsupportsthe10CFR50.92evaluationcontainedinAttachment1.ThereportisconsideredproprietarytoWestinghouseElectricCorporation.Assuch,anaffidavitforwithholdingfrompublicdisclosureisprovidedinAttachment4.Anon-proprietaryversionoftheWCAP(WCAP-13971)isprovidedinAttachment5.)81~.689402250130940215PDRADOCK05000315,PDR~pg.00pic,PDpi~~g5~c.(pealf-y.V
.~~V.
Dr.T~E.Hurley2AEP:NRC:1166KWebelievetheproposedchangeswillnotresultin(1)asignificantchangeinthetypesofanyeffluentthatmaybereleasedoffsite,or(2)asignificantincreaseinindividualorcumulativeoccupationalradiationexposure.TheseproposedchangeshavebeenreviewedbythePlantNuclearSafetyReviewCommitteeandbytheNuclearSafetyandDesignReviewCommittee.Incompliancewiththerequirementsof10CFR50.91(b)(l),copiesofthisletteranditsattachmentshavebeentransmittedtotheMichiganPublicServiceCommissionandtotheMichiganDepartmentofPublicHealth.Thisletterissubmittedpursuantto10CFR50.30(b),and,assuch,anoathstatementisattached.Sincerely,E.EDFitztrickVicePresidentdrAttachmentscc:A.A.BlindG.CharnoffJ.B.Martin-RegionIIINFEMSectionChiefNRCResidentInspector-BridgmanJ.R.Padgett STATEOFOHIO)COUNTYOFFRANKLIN)E.E.Fitzpatrick,beingdulysworn,deposesandsaysthatheistheVicePresidentoflicenseeIndianaMichiganPowerCompany,thathehasreadtheforgoingTECHNICALSPECIFICATIONCHANGESTOINCORPORATEWSTEAMGENERATORTUBEPLUGGINGCRITERIONandknowsthecontentsthereof;andthatsaidcontentsaretruetothebestofhisknowledgeandbelief.Subscribedandsworntobeforemethis~~dayof19~.NOTARYPUBLICRlrhD.HILLlfoTARYPUBS.'lt'TATEOFpH[pN
ATTACHMENT1TOAEP:NRC:1166KDESCRIPTIONANDJUSTIFICATIONOFCHANGES10CFR50.92ANALYSISFORCHANGESTOTHEDONALDC.COOKNUCLEARPLANTUNIT1TECHNICALSPECIFICATIONS ATTACHMENT1TOAEP:NRC:1166KPage1I.INTRODUCTIONThisamendmentrequestproposesachangetoTechnicalSpecification(TS)4.4.5(SteamGenerators)toincorporatearevisedacceptancecriterionforsteamgeneratortubeswithdegradationinthetubesheetrollexpansionregion.ThiscriterionforsteamgeneratortubeacceptancewasdevelopedbyWestinghouseElectricCorporationandisknownasW("F-Star").Thiscriterionwasdevelopedtoavoidunnecessarypluggingofsteamgeneratortubes.TheexistingT/Stuberepairingandpluggingcriteriaapplythroughoutthetubelength,butdonottakeintoaccountthereinforcingeffectofthetubesheetontheexternalsurfaceofthetubeintherollexpansionregion.Thepresenceofthetubesheetwillconstrainthetubeandwillcomplementitsintegrityinthatregionbyessentiallyprecludingtubedeformationbeyonditsexpandedoutsidediameter.Theresistancetobothtuberuptureandtubecollapseissignificantlystrengthenedbythetubesheet.Inaddition,theproximityofthetubesheetsignificantlyaffectstheleakbehaviorofthroughwalltubecracksinthisregion,i.e.,nosignificantleakagerelativetoplantT/Slimitsistobeexpected.TheWmethodologyanddeterminationoftheWdistanceareincludedinWCAP13970,entitled"WTubePluggingCriterionforTubesWithDegradationintheTubesheetRollExpansionRegionoftheDonaldC.CookUnit1SteamGenerators."Thisreport,preparedbyWestinghouseElectricCorporation,iscontainedinAttachment4.Anon-proprietaryversionofthereportisincludedinAttachment5.II.ESCRIPTIONOFTHECHANGESTheproposedchangesarethosenecessarytoincorporatetheWtubesheetregionpluggingcriterionintotheT/Ss.Thespecificchangesareasfollows:Arequirementisaddedtoinspect(intherollexpandedregion)alltubeswhichhavehadtheWcriteriaapplied.TherollexpandedregionofthesetubesmaybeexcludedfromtherequirementsofT/S4.4.5.2.b.l.DefinitionsforWdistanceandanWtubeareadded.Wdistanceisthedistancefromthebottomofthehardrolltransitiontowardthebottomofthetubesheetthathasbeenconservativelydeterminedtobe1.11inches(notincludingeddycurrentuncertainty).An,&tubeisatubewithdegradation,belowtheWdistance,equaltoorgreaterthan40$,andnotdegraded(i.e.,noindicationsofcracking)withintheWdistance.Thedefinitionof"Repair/PluggingLimit"(T/S4.4.5.4.a.6)ismodifiedtonotethatthe408repair/plugginglimitdoesnotapplytotheportionofthetubeinthetubesheetbelowtheWdistanceforWtubes.
ATTACHMENT1TOAEP:NRC:1166KPage2ArequirementisaddedtoreporttotheNRCtheresultsofinspectionsperformedunderT/S4.4.5.2foralltubesthathavedefectsbelowtheWdistanceandwerenotplugged.III.10CFR5092EVALUATIONTheamendmenthasbeenproposedtoaddresseddycurrentindicationsoftubedegradationwhichcanoccurintherollexpandedportionofthetubeswithinthetubesheetinthesteamgeneratorsattheCookNuclearPlantUnit1.Thesesteamgeneratorswerefabricatedwitha2.75inchpartialdepthrollexpansioninthetubesheet.InterpretationofeddycurrentdatafromtheCookNuclearPlantUnit1andsimilarplantshasshownapotentialforprimarywaterstresscorrosioncracking(PWSCC)withintherollexpandedportionofthetubeinthetubesheet.Itcanbeshownthattubepluggingorsleevingisnotrequiredinmanysuchcasestomaintainsteamgeneratortubeintegrity.UsingexistingT/Stubepluggingcriteriaforthelengthoftubewithinthetubesheet,manyofthetubeswithpotentialindicationswouldhavetoberepairedorremovedfromservice.Theproposedamendmentwouldprecludeoccupationalradiationexposurethatwouldotherwisebeincurredbyplantworkersinvolvedintubepluggingorsleevingoperations.Theproposedamendmentwouldalsoavoidlossofmargininreactorcoolantsystemflowandthereforeassistinassuringthatminimumflowratesaremaintainedinexcessofthatrequiredforoperationatfullpower.Reductionintheamountoftubepluggingorsleevingrequiredcanreducethelengthofplantoutagesandreducethetimethatthesteamgeneratorisopentothecontainmentenvironmentduringanoutage.Thepossibilityoftuberepairbysleevingshouldnotbeconsideredareasontoexcludeuseofthisproposedtubesheetpluggingcriterion,butshouldbeconsideredoneoftheoptionsusedtoaddressdegradationintheexpandedregionofthetube.Thedisadvantagesoftubeplugsnotedabovealsoapplytosomeextenttosleeves.Theproposedamendmentaddressestheactionrequiredwhendegradationhasbeendetectedinthemechanicallyexpandedportionofsteamgeneratortubeswithinthesteamgeneratortubesheet.Existingtuberepairorpluggingcriteriadonottakeintoaccounttheeffectofthetubesheetontheexternalsurfaceofthetube.Thepresenceofthetubesheetwillenhancetheintegrityofpotentiallydegradedtubesinthatregionbyprecludingtubedeformationbeyondtheexpandedoutsidediameter.Structural(burst)integrityoftubeswithsignificantthroughwallaxialpenetrationlengthisprovidedintherollexpandedarea.AnaxiallengthofrollexpansionequaltotheWlengthatthetopoftherollexpansionofthetubeintothetubesheetprovidessufficientstructuralintegritytoprecludepulloutofthetubeduetopressureeffects,evenafter
ATTACHMENT1TOAEP:NRC:1166KPage3assumingthatthetubehasexperiencedacompletecircumferentialseparationatorbelowthebottomoftheF+distance.ThissameaxiallengthofrollexpansionofthetubeintothetubesheetprovidesabarriertoleakageduringallplantconditionsforthroughwallcrackingofthetubeintheexpandedregionbelowW.TheproposedchangedesignatesaportionofthetubeforwhichtubedegradationofadefinedtypedoesnotnecessitateremedialactionexceptasdictatedforcompliancewithtubeleakagelimitsassetforthintheT/Ss.Asnotedabove,theareasubjecttothischangeisintheexpandedportionofthetubewithinthetubesheetofthesteamgenerators.TheWlengthhasbeendeterminedtobe1.11inches.Soundrollexpansionof1.11incheswillsatisfyallapplicablerecommendationsofRegulatoryGuide1.121,withregardtotubeburstcapability.Conformanceoftheproposedamendmentstothestandardsforadeterminationofnosignificanthazardasdefinedin10CFR50.92(threefactortest)isshowninthefollowing:1)OperationofDonaldC.CookNuclearPlantUnit1inaccordancewiththeproposedlicenseamendmentdoesnotinvolveasignificantincreaseintheprobabilityorconsequencesofanaccidentpreviouslyevaluated.Thesupportingtechnicalandsafetyevaluationsofthesubjectcriteriondemonstratethatthepresenceofthetubesheetwillenhancethetubeintegrityintheregionofthehardrollbyprecludingtubedeformationbeyonditsinitialexpandedoutsidediameter.Theresistancetobothtuberuptureandtubecollapseisstrengthenedbythepresenceofthetubesheetinthatregion.Theresultofhardrollingofthetubeintothetubesheetisaninterferencefitbetweenthetubeandthetubesheet.Tuberupturecannotoccurbecausethecontactbetweenthetubeandtubesheetdoesnotpermitsufficientmovementoftubematerial.Theradialpreloaddevelopedbytherollingprocesswillsecureapostulatedseparatedtubeendwithinthetubesheetduringallplantconditions.Inasimilarmanner,thetubesheetdoesnotpermitsufficientmovementoftubematerialtopermitbucklingcollapseofthetubeduringpostulatedLOCAloadings.Thetypeofdegradationforwhich,theWcriterionhasbeendeveloped(crackingwithacircumferentialorientation)cantheoreticallyleadtoapostulatedtuberuptureeventprovidedthatthepostulatedthrough-wallcircumferentialcrackexistsnearthetopofthetubesheet.Anevaluationincludinganalysisandtestinghasbeendonetodeterminetheresistivestrengthofrollexpandedtubeswithinthetubesheet.ThisevaluationprovidesthebasisfortheacceptancecriteriafortubedegradationsubjecttotheWcriterion.
ATTACHMENT1TOAEP:NRC:1166KPage4TheWlengthofrollexpansionissufficienttoprecludetubepulloutfromtubedegradationlocatedbelowtheWdistance,regardlessoftheextentofthetubedegradation.TheexistingT/Sleakageraterequirementsandaccidentanalysisassumptionsremainunchangedintheunlikelyeventthatsignificantleakagefromthisregiondoesoccur.Asnotedabove,tuberuptureandpulloutisnotexpectedfortubesusingtheWcriterion.AnyleakageoutofthetubefromwithinthetubesheetatanyelevationinthetubesheetisfullyboundedbytheexistingsteamgeneratortuberuptureanalysisincludedintheCookNuclearPlantFSAR.ForplantswithpartialdepthrollexpansionlikeCookNuclearPlantUnit1,apostulatedtubeseparationwithinthetubenearthetopoftherollexpansion(withsubsequentlimitedtubeaxialdisplacement)wouldnotbeexpectedtoresultincoolantreleaseratesequaltothoseassumedintheFSARforasteamgeneratortuberuptureeventduetothelimitedgapbetweenthetubeandtubesheet(approximately0.013inchdiametralgap).Theproposedpluggingcriteriondoesnotadverselyimpactanyotherpreviouslyevaluateddesignbasisaccident.LeakagetestingofrollexpandedtubesindicatesthatforrolllengthsapproximatelyequaltotheWdistance,anypostulatedfaultedconditionprimarytosecondaryleakagefromWtubeswouldbeinsignificant.2)Theproposedlicenseamendmentdoesnotcreatethepossibilityofanewordifferentkindofaccidentfromanyaccidentpreviouslyevaluated.ImplementationoftheproposedWcriteriondoesnotintroduceanysignificantchangestotheplantdesignbasis.Useofthecriteriondoesnotprovideamechanismtoinitiateanaccidentoutsideoftheregionoftheexpandedportionofthetube.Anyhypotheticalaccidentasaresultofanytubedegradationintheexpandedportionofthetubewouldbeboundedbytheexistingtuberuptureaccidentanalysis.Tubebundlestructuralintegritywillbemaintained.TubebundleleaktightnesswillbemaintainedsuchthatanypostulatedaccidentleakagefromWtubeswillbenegligiblewithregardtooffsitedoses.3)Theproposedlicenseamendmentdoesnotinvolveasignificantreductioninamarginofsafety.TheuseoftheWcriterionhasbeendemonstratedtomaintainthe,integrityofthetubebundlecommensuratewiththerequirementsofRegGuide1.121(intendedforindicationsinthefreespanoftubes)andtheprimarytosecondarypressureboundaryundernormalandpostulatedaccidentconditions.AcceptabletubedegradationfortheWcriterionisanydegradationindicationinthetubesheetregion,morethanthedistancebelowthebottomofthetransitionbetweentherollexpansionandtheunexpandedtube.ThesafetyfactorsusedintheverificationofthestrengthofthedegradedtubeareconsistentwiththesafetyfactorsintheASMEBoilerandPressureVesselCodeusedinsteamgeneratordesign.TheWdistancehasbeenverifiedbytestingtobegreaterthanthelengthofrollexpansionrequiredtoprecludebothtubepulloutand
ATTACHMENT1TOAEP:NRC:1166KPage5significantleakageduringnormalandpostulatedaccidentconditions.Resistancetotubepulloutisbasedupontheprimarytosecondarypressuredifferentialasitactsonthesurfaceareaofthetube,whichincludesthetubewallcross-section,inadditiontotheinnerdiameterbasedareaofthetube.TheleaktestingacceptancecriteriaarebasedontheprimarytosecondaryleakagelimitintheT/SsandtheleakageassumptionsusedintheFSARaccidentanalyses.Implementationofthetubesheetpluggingcriterionwilldecreasethenumberoftubeswhichmustbetakenoutofservicewithtubeplugsorrepairedwithsleeves.BothplugsandsleevesreducetheRCSflowmargin;thus,implementationoftheWcriterionwillmaintainthemarginofflowthatwouldotherwisebereducedintheeventofincreasedpluggingorsleeving.Basedontheabove,itisconcludedthattheproposedchangedoesnotresultinasignificantreductioninmarginwithrespecttoplantsafetyasdefinedintheFSARortheT/SBases.