ML18040A254

Forwards Proprietary & non-proprietary Repts from GE Re GL 94-03, Intergranular Stress Corrosion Cracking in Bwrs. List of Repts,Encl.Encls Withheld,Per 10CFR2.790(b)(i)

ML18040A254
Person / Time
Site:	Nine Mile Point
Issue date:	04/08/1997
From:	MCCORMICK M J NIAGARA MOHAWK POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML17059B487	List: ML17059B486 ML17059B488 ML17059B489 ML17059B493 ML18040A254
References
GL-94-03, GL-94-3, NMP1L-1200, NUDOCS 9704100242
Download: ML18040A254 (94)

Text

4,~+rI-CATEGORY2REGULATZNPORMATZON DISTRIBUTION'STEM (RIDE)ACCESSION NBR:9704100242 DOC.DATE:

97/04/08NOTARIZED:

YESFACIL:50-220 NineMilePoint.,Nuclear Station,Unit1,NiagaraPoweAUTH;NAME

-AUTHORAFFIL'I'ATION IMCCORMICK,M.J.

NiagaraMohawkPowerCorp.RECIP.NAME RECIPIENT AFFILIATION DocumentControlBranch(Document ControlDesk)DOCKET05000220

SUBJECT:

Forwardsproprietary anon-proprietary reptsfromGEreGL94-03,"Intergranular StressCorrosion CrackinginBWRs."Listofrepts,encl.Encls withheld,per C10CFR2.790(b)(i).

~ADISTRIBUTION CODE:APOIDCOPIESRECEIVED:LTR

/ENCLLSIZE:TITLE:Proprietary ReviewDistribution

-PreOperating License&Operating RTNOTES:RECIPIENT IDCODE/NAME PDl-1LAHOOD,DCOPIESLTTRENCL1111RECIPIENT

.IDCODE/NAME PD1-1PDCOPIESLTTRENCL11INTERNAL:

ACRSOGC/HDS3EXTERNAL:

NRCPDRILECENTER011110S1Z(.Prop11DC.ENNOTETOALL"RIDS"RECIPIENTS:

PLEASEHELPUSTOREDUCEWASTE.TOHAVEYOURNAMEORORGANIZATION REMOVEDFROMDISTRIBUTION LISTSORREDUCETHENUMBEROFCOPIESRECEIVEDBYYOUORYOURORGANIZATION, CONTACTTHEDOCUMENTCONTROLDESK(DCD)ONEXTENSION 415-2083(PTOTALNUMBEROFCOPIESREQUIRED:

LTTR7ENCL

NIAGARAMOHAWKCENERATI0NBUSINESSCROUPNINEMILEPOINTNUCLEARSTATION/LAKE ROAD,P.O.BOX63,LYCOMING, NEWYORK13093/TELEPHONE (315)349-2660FAX(315)349-2605MARTINJ.McCORMICK JR.P.E.VicePresident NuclearEngineering April8,1997NMP1L1200U.S.NuclearRegulatory Commission Attn:DocumentControlClerkWashington, DC20555RE:NineMilePointUnit1Docket50-220

Subject:

GenericLetter94-03"Intergranular StressCorrosion Cracking(IGSCC)inBoilingWaterReactors" Gentlemen:

BylettersdatedJanuary6,1995andJanuary23,1995,NiagaraMohawkPowerCorporation (NMPC)submitted anapplication forrepairstotheNineMilePointUnit1(NMP1)coreshroud.Theshroudrepairsanduseofstabilizer assemblies (tierods)weresubmitted asanalternate totherequirements oftheASMECode,SectionXI,asallowedby10CFR50.55a (a)(3)(i).

Thestaffprovidedapprovaloftheproposedalternate repairbyletterdatedMarch31,1995.Theapprovalletterandattachedsafetyevaluation requiredNMPCtosubmitre-inspection plansfortheshroudandrepairassemblies priortothenextrefueling outageplannedfor1997.ByletterdatedFebruary7,1997,NMPCsubmitted plansforre-inspection ofthecoreshroudverticalweldsandrepairassemblies inaccordance withthecriteriaprovidedbythe"BWRVesselandInternals Program"(BWRVIP)documentBWRVIP-07.

Duringthe1997refueling outage,NMPCconducted coreshroudverticalweldinspections pertheapproveddocuments andobservedverticalweldcrackingwhichexceededthescreening criteria.

Additionally, inspections ofthefourtierodassemblies foundthetierodnutstohavelostsomepreloadandidentified damagetothelowerwedgeretainerclipsonthreetierods.Furtherdetailsoftheasfoundconditions areprovidedinEnclosures 1and2.l(ByphonecallsonMarch20,1997andApril2,1997,NMPCinformedthestaffoftheinspection findingsandindicated thatanalysisoftheverticalweldcrackingandrestoration planoftheshroudtierodassemblies wouldbesubmitted totheNRCpriortorestartoftheunit.Thisletterandtheattachedenclosures providerootcause,corrective actionsandthefinaldesigndocumentation whichestablishes theacceptability oftheasfoundverticalweld$5OOigoAl3.3,llll3ll]llllGlllllll3lllllK'Illl',tlHllll, Wo'ILQo2Llg,.

ti(IR,(s(ist'p lg.t Page2crackingforaminimumof10,600operating hours(above200'F),determines anappropriate weldre-inspection

schedule, providesdetailsoftheactionstakentorestorethetierodstotheasdesignedcondition anddescribes amodification ofthelowerwedgeretainerclipdesign.Themodifiedlowerwedgeretainerclipsarepartofthetierodassemblies which,asnotedabove,arenotincludedundertheASMECodeSectionXIdefinition forrepairorreplacement.

Assuch,thedesigndetailsofthemodifiedretainerclipsarebeingsubmitted tothestaffforreviewandapprovalasanalternative repairpursuantto10CFR50.55a (a)(3)(i).

Theenclosedanalysesprovidejustification'for continued operation ofNMP1duringtheupcomingcycleutilizing theupdated10CFR50.55a approvalasproposedherein.Enclosures 1,2and5areconsidered bytheirpreparer, GeneralElectric(GE),tocontainproprietary information exemptfromdisclosure pursuantto10CFR2.790.

Therefore, onbehalfofGE,NMPCherebymakesapplication towithholdthesedocuments frompublicdisclosure inaccordance with10CFR2.790 (b)(1).Anaffidavit executedbyGEdetailing thereasonsfortherequesttowithholdtheproprietary information hasbeenincludedinEnclosure 7.Anon-proprietary versionofthesedocuments hasbeenincludedwiththisletterasEnclosure 8.I.CoreShroudTheNMP1coreshroudhasfourGEcoreshroudstabilizer assemblies installed.

Theseassemblies wereinstalled duringtheRFO-13(1995)refueling outage.Theinstallation wasdoneasapre-emptive repairofthecoreshroudhorizontal weldsHlthroughH7inlieuofbaselineshroudinspection ofthesehorizontal welds.TheGEshroudstabilizer designrequiresverticalweldintegrity inorderfortheshroudstabilizers tosatisfythedesignbasisassumption ofhorizontal weldsHlthroughH7beingthroughwallcracked360'.Thepre-andpost-shroudrepairinstallation inspection scopeduringRFO-13,includedasampleinspection oftheverticalweldsattheintersection ofaselectedhighfluenceweld(theH5weld).Theinspection included6inchesaboveandbelowtheH5locationalongtheV9,V10,V11andV12welds.Theinspection wasanenhancedvisualexamination performed fromtheinsidediameter(ID).Thisvisualexamination wasintendedasasampleinspection.

Thisinspection scopewasapprovedbytheNRCaspartofthesafetyevaluation report(SER)issuedfortheNMP1coreshroudstabilizer design.Theinspection oftheNMP1verticalweldsinthecurrentrefueling outage(RFO-14)wasperformed consistent withtheBWRVIP-07 guidelines forthereinspection ofBWRcoreshrouds.Theseguidelines alsoutilizedasampling

Page3approachfortheverticalcoreshroudwelds.TheoptionselectedbyNMPCwastocompleteavisualinspection of25%oftheequivalent totalverticalweldlengthfromeithertheoutsidediameter(OD)orID.Aspartoftheinspection plan,GEdefinedscreening criterion forminimumrequireduncracked verticalweldsonaperweldbasis.Theringsegmentweldswereexcludedfromtheverticalweldsrequiring inspection basedonGEanalysisoftheringsegmentweldssubmitted tothestaffforreviewbyletterdatedFebruary7,1997.Asaresultofinspection

findings, theinspection scopewasexpandedusinganenhancedvisualinspection methodsupplemented byultrasonic inspection (UT).B.TheinitialRFO-14inspection oftheverticalweldsidentified crackingovertheentireODlengthoftheV10weldusingenhancedvisualinspection techniques.

Theinspection planswerethenexpandedtoestablish minimumrequireduncracked ligamentontheverticalweldswhicharerequiredtomeettheshroudstabilizer repairdesignbasisassumptions.

TheverticalweldcrackingevidentontheODofboththeV9andV10weldswasextensive.

Theextentofcrackingidentified ontheODhadnotpreviously beenidentified atotherBWRs.Asaresult,acompletebaselineinspection oftheNMP1accessible portionsofcertaincoreshroudhorizontal andverticalweldswasperformed inordertoestablish anoverallmaterialcondition assessment oftheNMP1coreshroud.Detaileddescriptions ofbothverticalandhorizontal weldscrackingisprovidedinEnclosure 1.Theindividual inspection resultshavereceivedN.D.E.LevelIIIreviewbyGEandNMPCpersonnel.

Thedocumentation ofinspection resultsisbeingcompiledforfinalqualityassurance review.Thisreviewwillbecompleted byApril20,1997.C.Thisshroudbaselineinspection hasenabledNMPCtoestablish thatthecrackingattheverticalweldsV9andV10isconsistent withtheexpectedIGSCCcrackingofBWRcoreshrouds.Boththehorizontal weldcrackinginthebeltlineH4weldandtheverticalweldcrackinginthebeltlineV9andV10weldsisoccurring intheheataffectedzone(HAZ)ofthewelds.Theassessment oftheIGSCCcrackingisincludedinenclosedanalysesandreports.Severalindependent evaluations werealsoperformed forNMPCtoobtainanaccurateassessment ofthecauseandacceptability ofverticalweldcracking.

Theseevaluations haveconcluded thatthecrackingnotedontheverticalweldsV9andV10isIGSCC.Thestressesthatcausecrackingintheverticalweldsareweldresidualandfabrication stressesandtoalesserextentthestressresulting frominternalpressure(hoopstress).TheNMP1shroudhorizontal andverticalweldsareclearlysusceptible toIGSCC.ThehighcarbonType304 t

Page4stainless steelmaterialwasinitially sensitized bytheweldingprocess.Thematerial's susceptibility wasfurtherenhancedbysurfacecoldworkandsurfacestrainsfromthefabrication process.Irradiation wouldalsoaddtothesusceptibility overtheoperating time.Finally,thetensilesurfaceresidualstressesandsurfacefabrication stressesledtotheIGSCCinitiation.

Theinspection datafromUToftheseweldshasestablished thecrackingdepth.Thepatternofcrackdepthisconsistent withthecalculated fluenceaxialandradialprofiles, Theestimated fluencefortheseweldsisinthe2to4.5x10"n/cm~()1MEV).Thisfluenceplacestheseweldsinarangeforwhichtheradiation enhancedIGSCCconditions exist.Theevaluations performed haveconcluded thattheobservedcrackingisassociated eitherwithweldHAZorsiteswherefabrication relatedweldingorgrindingwasapparent.

Theoverallconclusion isthatthiscrackingisnotuniqueandcanbeattributed toweldingresidualstressesandfabrication fitupinducedstresses.

D.Thebaselineinspection hasidentified onelocationattheintersection ofH5andV9whereahorizontal crackintheHAZofH5haslinkedwithaverticalcrackintheHAZofV9.Thiscaseisisolatedandhasnotbeenidentified inotherlocations.

Infact,themajorityofthecrackingappearstostartapproximately 6to10inchesdownfromthehorizontal H4weldHAZ.Theshroudhorizontal andverticalweldbaselineinspection oftheNMP1coreshroudwhichhasbeenperformed providesapointofreference forfuturesampleinspection ofthecoreshroud.Thisbaselineandfuturesampleinspections willallowNMPCtomonitortheactualIGSCCcrackgrowthratewhichwillbeusedtomaintaintherequireddesignbasismargins.GEhascompleted analysesregarding thepotential impactthecoreshroudstabilizer assemblies couldhaveonverticalweldcracking.

Theresultshaveshownthatanyhoopstressinducedattheverticalweldsduetoshroudstabilizer thermalpreloadisnegligible.

Theoverallconclusion isthattheshroudstabilizers hadnoeffectontheshroudverticalweldcrackingidentified atV9andV10.Theverticalweld9andV10crackingwasreviewedbyindependent expertsinIGSCCcrackingofBWRcoreshrouds.Enclosure 3containstheresultsofaqualitative assessment ofthevisuallyobservedcrackingontheH4,V9,V10andH5welds.Thisevaluation hasconcluded thattheIGSCCcrackingissimilarinnaturetothecracksseeninotherBWRsandthatthespecificconditions fortheparticular crackingpatternscanbeexplained bynormalfabrication practices usedinmanufacturing thecoreshroud.Inanefforttobetterdefinehowthesefabrication processes canexplainthecracking, detailedfiniteelementmodelinghavebeenperformed.

Overalltheresultsshowthatthe

Page5weldingandfabrication processcanexplainthecrackingpatternobservedontheverticalwelds.Theseanalysescalculated through-thickness stressintensity solutions andcrackgrowthstudies.Theresultsclearlysupporttheboundinganalysisapproachbeingusedtodefinetheproposedoperating intervalbetweeninspections.

E.Ananalysisoftheverticalweldsusedtodefinetheproposedshroudverticalweldreinspection intervalhasbeenperformed consistent withapprovedBWRVIPshroudanalysismethods.ThecriteriaappliedarethosesetforthintheBWRVIPcoreshroudinspection andevaluation document.

Theapproachbeingappliedfortheverticalweldsanalysisassumedthatallhorizontal weldsarecracked360'hrough wallconsistent withthecoreshroudstabilizer designbasis.Theassumption ofhorizontal weld360'racking requiressufficient verticalweldintegrity toensurethatthedesignbasisassumption ofstackedrightcylinders ismaintained.

TheanalysisapproachreliesuponsizingofthethroughwallverticalweldcrackingwithUT.Thesethroughthickness crackshavebeenanalyzedconsistent withtheBWRVIPcoreshroudinspection andevaluation guidelines accounting forASMECodeSectionXIsafetyfactors,designbasisloads,inspection uncertainty consistent withtheBWRVIP-03 guidelines, andthecurrently boundingNRCcoreshroudcrackgrowthassumption of5x10~inches/hr.

Basedontheseassumptions, therequiredcoreshroudre-inspection intervalhasbeendetermined tobeatleast10,600operating hoursasdescribed inEnclosure 1.Theattachedanalysisoftheverticalweldsincludesanassessment ofthepotential leakagefrompostulated throughwallverticalcracking.

Theoverallthermalhydraulics assessment hasconcluded thattheleakagewouldbenegligible.

Theoverallconclusion isthatthisleakagehasnoimpactonthedesignbasisfornormalupsetoraccidentconditions.

TheattachedEnclosure 1providestherequireddetaileddiscussion onthissubject.Inconclusion, theverticalweldcrackingcondition hasbeenreviewedandbeendetermined tonotrepresent anunreviewed safetyquestionbasedonapplyingtheNRCapprovedcoreshroudinspection andevaluation guidelines.

Theseguidelines providetheanalysisbasistodefineanacceptable inspection intervalbasedonasfoundIGSCCcrackingofcoreshrouds.Therequiredintervalestablished bytheattachedanalysesis10,600hoursofoperation.

Page6II.CoreShroudStabBizer Assemblies (TieRods)A.Duringthecurrentrefueling outage,post-operational inspections wereconducted onthecoreshroudstabilizer (tierod)assemblies, Tieroddeficiencies werefound,including improperasfoundtorqueonthetierodnuts,anddamagetotheretainerclipsonthelowerspringwedges.Thesefindingsresultedinrootcauseevaluations andadditional inspections andtestingofthetierods.B.~~Enclosure 2containsthedetaileddataontheas-foundcondition, rootcauseofthosedeficiencies, validation oftherootcauseandcorrective actionstaken.Gapswereidentified ontheclevispintolowersupporthookcontactandunderthetierodnuttotopsupportcontact.Itwasdetermined thatpreloadofthetierodshadbeenlost,tosomedegree,oneachtierod.Also,thelowerspringwedgeretainerclipwasbrokenatthe90'ierodlocationandvisiblydamagedatthe270'nd350'ierodlocations.

The90'ierodlowerspringwedgewasfoundbottomedonitsguiderod,notincontactwiththevesselasoriginally installed.

Theremaining contactpoints,springsandretainerclipswerefoundintheirproperpositions.

C.Therootcauseforthetieroddegradation isattributed torecognition thatthetieroddesigndidnotconsidertheeffectofinstallation tolerances forthelowersupportboltholes.Becauseofthis,theinstallation procedures didnotcontainspecificcriteriaforthelocationofthetoggleboltsduringinstallation ofthelowersupport.Thelowersupporttoggleboltsarenominally 4.000"indiameter.

Themeasuredelectricdischarge machining (EDM)holesintheshroudconerangedfrom4.090"to4.110".Sincethepositionofthelowersupportboltswithinthemachinedholeswasnotprocedurally controlled duringinstallation, therelativepositionoftheboltswithintheholeswasvariable.

Duringheatup,theexpansion oftheshroudandtierodsgenerates aforcesufficient enoughtoovercometheinstalled frictionforcesandmovethelowersupportuptheshroudcone.Thistranslates intoaverticalmovementofthetierod.Thismovementwassufficient toapplyaloadonthelowerspringwedgeretainerclipsuchthatitfailedwithinonecycleofoperation.

Additionally, thelowerspringwedgeretainerclipwasnotdesignedtoaccommodate differential movementgiventhefrictional loadsbetweenthevesselwallandthelowerspringwedgeduringnormalandtransient conditions.

Page7D.Subsequent tothesefindingsandrootcauseevaluation, aninstallation procedure wasdeveloped torestorethetierodstotheiroriginaldesignbasiscondition.

Eachtierodwasjackedatthreelocations duringtierodnuttorquingtoremoveanygapsassociated withinstallation tolerances.

Jackswereplacedunderthelowersupport,onthevesselsideofthelowersupporttopushituptheshroudconetoremovetheclearances betweenthetoggleboltsandtheshroudsideoftheconeholes.Following performance oftherevisedinstallation procedure inspections werecompleted oneachtierodtoverifytheabsenceofgaps,propercontactandposition.

Asaresultoftheseinspections, itwasdiscovered thatthemiddlesupportwasnolongerincontactwiththevesselonthe90'nd166'ierod.Thiswascausedasaresultofthelowersupportassemblybeingmoveduptheconetowardstheshroud.Themiddlesupportdimensions arebeingretakenandnewmiddlesupportswillbeinstalled priortoreload.Otherlocations onthetierodassemblies withthepotential forgapsandnon-conforming conditions wereinspected.

Noadditional deficiencies werenoted.AsummaryofNMPC's10CFR50.59 safetyevaluation concerning modification tothecoreshroudrepairtierodassemblies isprovidedinEnclosure 4.E.Calculations wereperformed toevaluatethemaximumpotential displacements ofthetierodrelativetothelowerspringwedge.Thisresultedinaredesignofthelowerwedgeretainerclip.Themodifieddesignisdescribed belowandaccommodates expectedmovements.

Thenewretainerclipswillbeinstalled duringthecurrentrefueling outage.Theclipshavebeenfabricated fromX-750,analyzedinaccordance withtheASMECode,andmeetoriginaldesigncriteriaforthetierods.F.Thefunctionofthelowerwedgeretainerclipistoretainthelowerwedgeintheproperpositionduringinstallation.

Itwasnotdesignedtoexperience operational loads.Lowerwedgetovesselcontactwasassumedtomoveandaccommodate differential thermalexpansion betweenthetierodassemblyandthevessel.Asexplained inEnclosure 2,thefrictionforcebetweenthewedgeandthevesselwassufficient topreventmovementofthewedgeduringthermalgrowthofthetierodassembly.

Thelatchportionoftheretainerclipbecameloadedresulting intheoverstressed condition oftheretainerclipanditssubsequent failure.

Page8Theretainercliphasbeenredesigned toaccommodate movementduringnormalandtransient conditions.

Theredesigned retainerclipswillbeinstalled priortoreload.Enclosure 5,"DesignReportforImprovedShroudRepairLowerSupportLatches,"

providestheresultsofanevaluation performed fortheredesigned latchanddemonstrates acceptability oftheredesigned latchanditsuseintheoriginaltierodassembly.

III.FurtherActionsNMPChasanalyzedtheasfoundcondition oftheshroudverticalweldsandhasestablished thattheplantcanbeoperatedsafely.Aconservative intervalforre-inspection oftheweldshasbeenestablished asdescribed inEnclosure 1.Re-inspection, including tightness checksofthetierodnuts,willbeperformed afterapproximately 10,600hoursofoperation andNMPCwillhaveplansforacontingency repairshouldonebeneededatthattime.NMPCplansadditional

analyses, duringtheupcomingcycle,whichmayjustifyextension ofthere-inspection intervalfortheshroudverticalwelds.Theresultsoftheseanalyseswillbesubmitted totheNRC,ifappropriate.

Aboatsampleofcrackedmaterialwillbemechanically removedfromashroudweldHAZatanappropriate locationpriortorestartfromRFO-14.Asalongertermaction,NMPCplanstoperformanalysisonthesampletoestablish thepresenceofIGSCC,theageofthecracking, whethercrackgrowthhasarrestedandtoinvestigate anyotherpotential contributing mechanisms.

Thismetallurgical sampleistobeusedtohelpNMPCandtheindustrybetterunderstand theIGSCCcrackingoftheBWRcoreshroudverticalwelds.IV.Inspection ofOtherInternals NMPChasperformed inspections overtheoperating lifeoftheplanttomeetseveralASMECode,industry, BWRVIPandAugmented Regulatory requirements.

Theseinspections providethebasisforanoverallcondition assessment oftheRPVinternals.

Specifically, theinspections performed duringthecurrentrefueloutageontheinternalcoresprayannuluspipingandcoresprayspargers, showednocrackgrowthofpreviously identified indications onthespargers.

Theannuluspipingwasfoundtobewithoutflaws,including thecriticalweldsatcrevicedlocations.

Asummaryofinspections performed todateofotherinternals isprovidedinEnclosure 6.NMPChasperformed anevaluation ofthetierodrestoration activities andtheasfoundcondition oftheverticalweldsandfoundthemacceptable forcontinued service.NMPCrequestsapprovalofthefinaldesigndocumentation fortheproposedmodification ofthetierodretainerclipsbyarevisiontotheexistingNRCshroudrepairsafetyevaluation

Page9submitted asanalternate repairunder10CFR50.55 (a)(2)(i).

ReceiptofNRCapprovalisrequested byApril20,1997.Verytrulyyours,MartinJ.McCormick Jr.VicePresident

-NuclearEngineering MJM/MSL/lmc Enclosures xc:Mr.H.J.Miller,NRCRegionalAdministrator, RegionIMr.S.S.Bajwa,ActingDirector, ProjectDirectorate I-l,NRRMr.B.S.Norris,SeniorResidentInspector Mr.D.S.Hood,SeniorProjectManager,NRRRecordsManagement

UNITEDSTATESNUCLEARREGULATORY COMMISSION IntheMatterofNiagaraMohawkPowerCorporation NineMilePointUnitj.DocketNo.50-220MartinJ.McCormick Jr.,beingdulysworn,statesthatheisVicePresident

-NuclearEngineering ofNiagaraMohawkPowerCorporation; thatheisauthorized onthepartofsaidCorporation tosignandfilewiththeNuclearRegulatory Commission thedocumentattachedhereto;andthatthedocumentistrueandcorrecttothebestofhisknowledge, information andbelief.MartinJ.cCormickJr.VicePresident

-NuclearEngineering Subscribed andswornbeforeme,inandfortheStateofNewYorkandtheCountyofQ~~ethis8-dayofApril,997.NOTARYPUBLICJOHNCJOSHNoteyPublic,8tete ofSeeYo4No.4837303 CueINedInGsveeoCemtyCommission ExpfresFeb.28,19qe 88QL0ftHOt,CmY+wN4etatBAYRRytafaHaacrm~xigampo"~~0nlt."PiiHeuQ Pf<E~~3U"DOXIEfi

INDEXOFENCIOSURESENCLOSURE 1Assessment oftheVerticalWeldCrackingontheNMP1ShroudENCLOSURE 2ShroudRepairAnomalies, NineMgePointUnit1,RFO14ENCLOSURE 3NineMilePointUnit1CoreShroudCrackingEvaluation ENCLOSURE 410CFR50.59 SafetyEvaluation 96-018,Revision1ENCLOSURE 5DesignReportforImprovedShroudRepairLowerSupportLatchesENCLOSURE 6Inspection HistoryENCLOSURE 7Affidavit (GE)ENCLOSURE 8Non-Proprietary VersionofReports ENCLOSURE2 SHROUDREPAIRANOMALIES NINEMILEPOINTUNIT1RFO14..9704100242

ENCLOSURE 410CFRSO.59SAFETYEVALUATION 96-018,REVISION1 0

1050.59SAFETYEVALUATION SURYMODIFICATION TOTHECORESHROUDREPAIRSTABILIZER ASSEMBLIES Ashroudrepairmodification wasinstalled inNineMilePoint1NuclearPowerPlanttoprovideanalternate loadpathfortheType304stainless steelcircumferential welds,HlthroughH7.Themodification ensuresthestructural integrity ofthecoreshroudbyreplacing thefunctionofweldsHlthroughH7with4stabilizer assemblies andfourcoreplatewedges.Inthecourseofthepost-installation inspection oftheshroudrepair,threedeviations wereidentified, evaluated andwerefoundacceptable forcontinued plantoperation throughthenextcycle.Afteradditional reviewandevaluation, additional modifications areproposedtoprovidethelongtermcorrective actions.Duringthespring1997refueling outage,twoadditional deficiencies werefoundontheshroudrepairhardware.

Eachofthefourshroudrepairstabilizer assemblies werefoundtohavelessthantheoriginalinstallation preloadandoneofthelowerwedgelatcheshadfailedinservice.

Twootherlowerwedgelatchesalsoappearedtobedegraded.

Thelatchisawishboneshapedpiece,thatisintendedtopreventrelativemotionbetweenthelowerwedgeandthelowerspringwiththeassumption thatslidingwouldoccurbetweenthelowerwedgeandtheRPVwall.Thedeviations werefoundduringrequiredaugmented In-service Inspections gSI)anddu'ringtheplannedreplacement oftheshroudstabilizer assemblyat270'.Therootcauseofthestabilizer verticallossofpreloadwasduetoclearances betweenthelowersupporttoggleboltsandtheholesintheshroudsupportcone.Theimportance oftheclearance betweenthetoggleboltsandtheholewasnotrecognized andnotincorporated intotheinstallation engineering documentation.

Thisallowedthelowersupporttomoveuptheshroudsupportconetowardtheshroudwhentheplantreachednormaloperating conditions.

Therootcauseofthelatchfailureisanincorrect designassumption regarding slidingatthevesseltolowerwedgeinterface.

Adetaileddiscussion oftheas-foundcondition ofthestabilizer assemblies andtherootcauseofthedeviations isincludedinReference 27.Thisevaluation considers theadditionofthethreemodifications described belowandhowthesemodifications afreettheSafetyEvaluation fortheCoreShroudRepairDesign,Reference 23,31and32.Thereferences inPartEretainthesamenumberswithadditional references applicable tothemodifications.

~difzatiga 3.Thelowerspringofonestabilizer assemblybearsontheblendradiusofthe270'ecirculation nozzle.Theproposedmodifications istoreplacethetierodandspringassemblywithonehavingthespringontheoppositesideofthetierod.Thisproposedmodification relocates thespringtobearontheRPVasintended.

Madii@~2ThelowerspringcontactwiththeshrouddonotextendbeyondweldH6Aatanyofthefourlocations.

Asresult,thebarrelsectionbetweenweldsH5andH6Aisnotlaterally restrained duringasteamlineLOCAcombinedwithaDBEaswasintended.

Theproposedmodification addsanextension piecetoextendthespringcontactbeyondweldH6Aandrestorethisfeaturetoitsintendedfunction.

Theextendedcontactandthecoreplatewedgesalsoprovideanredundant loadpathbetweenthecoreplateandthelowerspringaswasintendedintheintheoriginaldesign.Page1of17 0'i TheabovetwonotedmoacationshavebeenreviewedandapprovebytheNRCinReference 32.ggg*PIPg*gglPlddIdppPIPtheaxialtightness ofthestabilizer assemblies.

Thelowerwedgelatchesmaybecomeloadedduetodifferential verticaldisplacement greaterthanintendedbytheoriginaldesignofthelatches.Therearetwocorrective actions.Thefirstistoremovetheclearance betweenthetoggleboltsandtheshroudsupportcone.Thishasbeenaccomplished withtheReference 28procedure.

Theremovaloftheclearances restoresthestabilizer assemblies totheiroriginally intendeddesignanddoesnotrepresent amodification.

Thesecondcorrective actionwastoinstallnewmodifiedlatcheswhicharemoretolerantofdifferential verticaldisplacement.

A.l~0'ollowing theinstallation ofthecoreshroudrepairavisualinspection oftheas-installed assemblyhardwareshowedthelowerspringwedgeonthe270'tabilizer assemblybearingontheblendradiusoftherecirculation nozzle.ThewedgewasintendedtobearontheRPVwall.Theproposedmodification istoreplacethetierodandspringassemblywithonehavingthespringontheoppositeside.Themodification movesthespringsufficiently suchthatitwillbearontheRPVoriginally asintended.

Themodification utilizes.

existinghardwarewhichwasbuiltasasparealongwiththeotherstabilizer assemblies.

Onlyminorreworkisrequiredtorelocatethelowerspringandthereworkhasnoaffectonthehardwarefunction.

Themodification doesnotrequireadditional penetrations throughtheshroudsupportconeoranyadditional EDMwork.Themodification usesthesamelowersupportandupperspringassemblies andthereisnochangetotheactualtierodlocation.

Additional analysishasbeendonetoaddressthedesignwherethelowerspringsarenolongerlocated90'part.Thenon-uniform lowerspringspacingaffectsthenetspringcharacteristic whenthehorizontal seismicloadisdirectedbetweentwosprings.Theanalysisshowtheloadsanddisplacements remainacceptable forallconditions.

A.2~6QQQQ~ThelowerspringcontactswiththeshrouddonotextendabovetheH6Aweldaswasintended.

ThedesignfunctioncanberestoredbyaddingaUshapedextension piecetoextendbeyondweldH6A.Theextension piecefitsovertheexistinglowercontactwiththelegsoftheUextending aroundthesidesoftheexistinglowercontact.Thestepsattheendsofthelegsfitunderthelowercontacttopreventaxialmovement.

Atangatthetopextension fitsinthegapbetweenthelowercontactandthelowerspringtorestrictthehorizontal movement.

Theaddedextension pieceiscapturedinalldirections ontheexistinglowercontact.Thelegsoftheextension arespringloadedtoprovideapositiveclampingforceagainstthesidesofthelowercontact.Thespringforceisnotrequiredtocapturethepartbutissufficient topreventanyfreemovementorvibrations.

Withthisarrangement, theaddedextension pieceiscapturedinalldirections andisheldsecurebythespringloadedclampingforce.Thehardwareforbothmodifications isdesignedandfabricated tothesamedesignbasis(Ref.1)astheoriginalshroudrepairhardware.

Thedesignlifeofallrepairhardwarewillbefortwenty-five years(theremaining lifeoftheplant,pluslifeextension beyondthecurrentoperating license),

toinclude20Effective FullPowerYears.Themodifiedstabilizer assemblyincludesthesamedesignfeaturesastheoriginalhardware.

Allpartsarelockedinplaceorcapturedbymechanical devices.Thestressesinthestabilizer donotchangeandPage2of17 0h~'If4 remainlessthantheallowestresses.

Therepairhardwareisfabricated fromintergranular stresscorrosion resistant material.

Thereisnoweldingintheconstruction orinstallation oftheshroudrepairhardware.

Thefastfluxlevelsatthestabilizers arewellbelowthedamagethreshold whichcouldresultinthedegradation ofmaterialproperties.

After25yearsofoperation, themaximumfastfluenceattheshroudrepaircomponents willbewellbelowthevaluetocausedamage.Therefore, itisveryunlikelythatacomponent willfail.A>LAXCEThedesignofthenewimprovedshroudrepairlowersupportlatcheshavebeenanalyzedindetailinReference 30.Thedesignofthenewlatchesmaintains theoriginaldesignfunction.

Thefunctionoftheoriginallatchwastosecurethewedgetothelowerspring.Thisis'primarily neededwhenthewedgeloosescontactwiththereactorvesselwall.Thisisanimportant functionsincethewedgewillotherwise slidedownandcreateexcessive gaps.Thenewlatchdesignmaintains thewedgesupportcapability andcanreadilysupportthedeadweightandflowforceswhichcouldacttopushthewedgedown.Thenewlatchdesignincorporates anotherspringwhichcantolerateverticaldisplacements.

Therefore, theoriginalfunctional requirement isaccomplished whileaddingmoreflexibility intheverticaldirection toaccommodate verticaldisplacements.

Underthemostprobableoperating andslidingconditions thenewlatchdesignisexpectedtoperformsatisfactorily fortheremaining lifeoftheplant.Evenforworstcasepostulated conditions, thelatchiscapableofoperating withoutfailurethroughout thenextoperating cycle.ThenewlatchescantolerateadifFerential verticaldisplacement fortheworstcasethermaltransient event(lossoffeedwater event)withoutexperiencing anoverstress condition.

Alsofornormalplantoperation, themaximumverticaldifFerential displacement underprobablewedgeinteraction conditions (assuming noslippagebetweentheRPVandthewedge)is0.10inches.Underthisdeflection thestressesinthenewlatcheswillbelessthanthestresslimitestablished topreventstresscorrosion inX-750materialfora40yearlifetime.

Acomparison oftheoriginallatchdesigntothenewdesignhasbeenperformed usingcommonfiniteelementmodelingmethods.Theresultsshowthatthenewlatchis8to12timesmorecapableoftolerating verticaldisplacements thantheoriginaldesign.Thisorderofmagnitude improvement inthedesignprovidesassurance thatthenewlatchwillperformsatisfactorily inthenextoperating cycle.The'removal oftheclearance betweenthetoggleboltsandtheshroudsupportconewillassurethatthetierodverticalforceswillbeasintendedintheoriginaldesign.Theverticalclearances inthestabilizer assemblies wereeliminated usingtheprocedure includedinReference 28.Eachofthefourstabilizer assemblies werethentorquedtotheoriginalrequiredinstallation value.Withthetierodinatightcondition atstartup,theproperverticalthermalexpansion loads.canbeaccomplished duringtheheatupofthereactor,andmaintaintheholddownforcesontheshroudthroughsubsequent heatupsandcooldowns.A.4Theinstalled stabilizers tierodsarefabricated entirelyfromthetype316,316Lstainless steel(bothwithacarboncontentlessthan0.02%)oralloyX-750.Theaddedcontactextension andmodifiedlatchesarefabricated fromalloyX-750.Thereplacement components forthe270'ierodmodification willbefabricated usingthesamematerials asthecurrently installed stabilizers.

Thefabrication requirements forthetwoproposedtierodmodifications willbeinaccordance withthepreviously approvedfabrication requirements fortheNMP-1coreshroudstabilizers.

Thereisnoweldingrequiredduringfabrication orinstallation.

Fage3of17

BhKLLYSIS:

Theapplicable criteriaandconformance forthisanalysisisasfollows.ThecriteriaisthesamecriteriathatwasusedfortheoriginalShroudRepairDesignSafetyEvaluation, Reference 23.Theconformance sectionsspecifically addressthethreeproposedmodifications.

B.1IhsigaLifeKritaig:Thedesignlifeofallrepairhardwarewillbefortwenty-five years(theremaining lifeoftheplant,pluslifeextension beyondthecurrentoperating license),

toinclude20Effective FullPowerYears.B.1.1RgmizIhsignLiRThehardwareforthethreemodifications isfabricated tothesamedesignbasis,including materialrequirements, astheoriginalshroudrepairhardware.

Allrepairhardwarehasbeendesignedforadesignlifeoftwenty-five years(theremaining lifeoftheplant,pluslifeextension beyondthecurrentoperating license),

toinclude20Effective FullPowerYears.Thisrequirement isdocumented inreference l.Assuringanadequatedesignlifeismainlyamaterialselection andprocesscontroleffort,forthisequipment.

Theselection oflowcarbonstainless steelsandhighnickelalloysassures'the bestavailable materials forthenuclearreactorenvironment.

Solutionannealing andsensitization testingareimposedtoguardagainstintergranularstresscorrosion cracking(IGSCC).Processchemicalcontrolsareimposedtoassurethatcontamination byheavymetalandchlorineorsulfurcompounds willnotoccur.Thisisthesamedesignselections andcontrolsimposedforastandardfortyyearphntlife.Thereisnothingintheequipment orinstallation thatputsaspecificlimitonhowlongitcanbeused,suchascreeporradiation degradation.

ThestressesinthelatcharewithinASMEcodelimitsandthelatchisanalyzedtoberesistant tostresscorrosion foraminimumof2yearsassumingconservative worstcasedisplacements intheretainer.

Itisfullyexpectedthattheretainerwilllastforasignificantly longertimebasedonthefactorofimprovement whichhasbeendemonstrated fromtheoriginaldesign.Fortheexpectedslidingcasewherethemovementisalwaysalongthewedgdspring interface, theretainerwilllastforaleasttheremaining lifeoftheplant.Theretainers willbeinspected atthenextoutagetodetermine whichtypeofslidingisoccurring inordertovalidatetheservicelifetimeoftheretainers.

B2Saki'eHgu Bmh{Crhczig:

IToassurethesafetydesignbasisissatisfied andthatthesafeshutdownoftheplantandremovalofdecayheatarenotimpaired, therepairhardwareshallassurethatthecoreshroudwillmaintainthefollowing basicsafetyfunctions:

Tolimitdeflections anddeformation toassurethattheEmergency CoreCoolingSystems(ECCS)canperformtheirsafetyfunctions duringanticipated operational occurrences andaccidents.

Maintainpartitions betweenregionswithinthereactorvesseltoprovidecorrectcoolantdistribution, forallnormalplantoperating modes..Providepositioning andsupportforthefuelassemblies, controlrods,incorefluxmonitors, andothervesselinternals andtoensurethatnormalcontrolrodmovementisnotimpaired.

Page4of17

.0l'I ThechangesinthelowerspringspacingaQectsthesystemspringcharacteristics forloadsactingbetweentwocontacts.

Additional seismicanalysis(Reference 24)calculated coresupportdisplacements fortheboundingconditions.

Thesectionbelowisrevisedtoincludethemaximumdisplacements basedonmodifiedlowerspringspacingandincludesthegapbetweentheshroudandthecontactextension.

Alldisplacements remainacceptable.

Thenewmodifiedlatchdesignonthelowerspringwedgedoesnote6ectthemaximumdisplacements below.Thecorespraypipinganalysisperformed tosupporttheshroudrepairincludedashrouddisplacement of0.904in.horizontally and0.65in.vertically, causedbyafaultcondition.

Thisdisplacement willnotcreateanunacceptable loadingcondition intheECCSpipingandtherefore willperformitsintendedsafetyfunction.

Theproposedmodifications donotchangethemaximumdisplacements calculated fortheoriginalshroudrepairattheuppershroud.Therefore thereisnochangeinloadingofthecorespraypiping.Theproperdecayheatremovalrequiresthattheshroudtoremainasaflowboundarytoforcewaterthroughthefuelandnotallowalargeleakageintothedowncomer region.Themaximumpermanent horizontal ofFsetofadjacentshellsections, thatarenotdirectlysupported byeithertheupperorlowersprings,islimitedbystructural stopsto0.75in.Sincethewall'oftheshroudis1.5in.thick,theshroudwillstillfunctionproperlyasaflowboundarywithinthereactor.ThesafeshutdownoftheplantisafunctionoftheSCRAMcapability.

Thecoresupportplateandthetopguidemustbekeptalignedwithintestlimitssothatfrictionbetweenthecontrolrodsandfuelbundleswillnotimpairpropermotion.Theworstcasecondition existswhenthetopguidemovesonedirection andthecoresupportmovestheopposite.

Thiscreatesthemaximumanglebetweenthefuelbundlesandtheguidetubes.Themaximumtemporary calculated horizontal displacement ofthetopguideis0.904in.andthemaximumforthecoresupportis0.85in.Thecorresponding allowable displacement are1.87in.and1.49in.Thereisnocalculated permanent horizontal displacement ofthetopguideandthemaximumpermanent displacement forthecoresupportis0.48inches.Thecorresponding allowable coresupportpermanent displacements is0.67inches.B.3ZbmDr~iKCilain):

Repairstothecoreshroudarenotrequiredtototallypreventleakagefromthecoreregionintothedowncomer annulus.However,thedesignshallensurethatcrackedweldsdonotseparateundernormaloperations asaminimum.Designwillaccountforleakagefrom.theregioninsidetheshroudintotheannulusregionduringnormaloperation.

Theleakageshouldnotexceedtheminimumsubcooling requiredforproperrecirculation pumpoperation andthecorebypassflowleakagerequirements assumedinthereloadsafetyanalysisshallbemaintained.

Thedesignwillalsoverifyacceptable leakagethroughtheflowpartition resulting fromweldseparation duringaccidentandtransient events.B31Elm2'ztithuTheoriginalshroudrepairdesignensuredthatcrackedweldswillnotseparateundernormaloperations.

Theoriginalshroudrepairdesignaccounted forleakagefromtheregioninsidetheshroudintotheannulusregionduringnormaloperation.

Theleakagedoesnotexceedtheminimumsubcooling requiredforproperrecirculation pumpoperation andthecorebypassflowleakagerequirements assumedinreloadsafetyanalysesismaintained.

Page5of17 05 Therearenorequiremen rallowable leakageduringtheaccidentOCAand/orseismic).

Aftertheaccident, theleakageislimitedbytheallowable deflections suchthattheshroudsectiondoesnotdisplacesuf5ciently toopenanyverticalflowareas.Themaximumpermanent horizontal displacement ofashroudcylindrical sectionthatisnotdirectlysupported byeithertheupperorlowerspringsislessthan0.75inch,whichisequaltoonehalfofthethickness oftheshroud.Thus,leakageafteranaccidentwillbelimitedtotheleakagethroughacrack.Sincethepressuredifference acrosstheshroudissmall,theleakagewillbesmall.Thethreeproposedmodifications havenoaffectonthepotential weldcrackseparation oranypotential leakagepath.Thethreemodifications donotrequireanynewholesorpenetrations throughtheshroud/shroud support.Therefore theleakagecalculations andperformance predictions inReferences 23and29remainvalid.Theaddedcontactextension providesassurance themaximumpermanent displacement oftheshroudcylinderbetweenweldHSandH6Aremainslessthan0.75inch.8.4ZhxImimaiXihzafhgCdbxig:Therepairshallbedesignedtoaddressthepotential forvibration, andtokeepvibration toanacceptable level.Thenaturalfrequency oftherepairedshroud,including therepairhardware, shallbedetermined.

Thevibratory stressesshallbelessthantheallowable stressesoftherepairmaterials.

Forcingfunctions tobeconsidered includethecoolantflowandthevibratory forcestransmitted viathe'endpointattachments fortherepair.Testingmaybeusedasanalternative ortosupplement thevibration analysis.

UB4lBBSIYB~U'KEl{~

Theoriginalshroudrepairwasdesignedtoaddressthepotential forvibration, andtokeepvibration toaminimum.Thenaturalfrequency oftherepairedshroud,including therepairhardware, hasbeendetermined.

Theusagefactorduetocyclicstressescausedbyvibration willbelessthan1.0forthedesignlifeoftherepairhardware.

Forcingfunctions considered includedthecoolantflowandthevibratory forcestransmitted viatheendpointattachments fortherepair.Detailsoftheoriginalvibration analysisareprovidedinReference 23.Thethreerepairmodifications havenoaffectonthenatural&equencyofthestabilizer assemblyoronthevortexsheddingfrequency.

Therefore theoriginalvibration evaluation inReference 23remainsvalidforthestabilizer assemblies.

Thepotential forvibration ofthenewextension pieceshasbeenconsidered.

Forcingfunctions considered, includedthevibratory forcestransmitted fromthestabilizer assemblies andcoolantflow.Thestabilizer vibratory forcesarelow,asdemonstrated intheoriginalvibration

analysis, therefore vibratory forcesimposedontheextension piecesarelow.Thecoolantflowwillnotvibratethelowercontactextensions becausetheextensions arecapturedinalldirections ontheexistinglowerspringassembly.

Thelowercontactextension isa"U"shapedpartwhichfitsaroundtheexistinglowercontact.Stepsattheendsofitslegsextendunderthelowercontacttopreventaxialmovement.

Atangtowardsthetopfitsinthegapbetweenthelowercontactandthelowerspringtopreventhorizontal movement.

Apositivespringforcefromthelegskeeptheparttightandpreventrandomvibrations.

TheonlytimethatFIVisofinterestiswhenthelowerwedgelosescontactwiththevesselwall.Thiscanoccurduringhydrotest, maximumseismicconditions, andduringthelimitingupsetthermalfeedwater event.Theseeventshaveshortdurationwiththelongestpotential durationbeing8hoursforthehydrotest event.Thelossofcontactatthelowerspringsupportisnotaconcernineitherthetierodassemblyor-thesubassembly ofthelatchandlowerwedgeforthefollowing reasons:Page6of17

.0' Thetimewhencontislostisarelativeshortdurationandteassociated numberofcyclesislimited.Anindependent calculation ofthenewlatchandlowerwedgeassemblyshowsthatthenatural&equencyissuKciently hightoavoidflowinducedvibration.

Theclearance whichiscreatedbetweenthewedgeandthevesselwallislessthan0.050"whichwilllimitthemotionofthelowerwedgeinthelateraldirection.

Thispreventsanysignificant contactforcesfrombeingproduced, andcontactwoulddampenoutanyexcitation ofthelowerwedge.Therelativeradialmovements betweenthevesselandtheshroudaresuchthatsurfacecontactislikelytoremainatoneofthetwosurfacesduringthepostulated events.Evenpostulating thatnosupportispresentatthelowerspring,analysishasbeenperformed forthe'ierodassemblywhichdemonstrates thatflowinducedvibration willnotoccur.)Inconclusion, noneoftheshroudrepaircomponents aresusceptible toflowinducedvibration whencontactislostatthelowerspringcontact.B.SLmliugmExidiugIaimmlIncreased stressonexistinginternalcomponents, usedintherepair,isacceptable aslongasthecurrentplantlicensing basisaremet.Increases inappliedloadshallbedemonstrated tobeacceptable.

Therepairshallbedesigned'so astoproduceacceptable loadingontheoriginalstructure oftheshroud,consistent withthecriteriaprovidedherein.Therepairshouldminimizestressesintroduced intotheshroudconsistent withthecriteriaprovidedsoastonotaggravate furthershroudcracking.

Therepairshouldminimizetheloadingonthesupporting structures oftheshroud,suchastheshroudsupportconeandtheRPVwall,tostaywithintheoriginaldesignallowable stressesofthesestructures.

~Supplemental seismicanalysisfortheproposedmodifications shallconformtothesamemethodology andcriteriausedintheoriginalshroudrepairseismicanalysisasdocumented intheFSAR.~~ILQKIJHlg911EXhfhlgI1lfCKBBl Stressesontheoriginalstructure oftheshroud,whicharedirectlyimpactedbytheshroudrepairhardware, havebeendemonstrated tobeacceptable.

Theresultsofthisevaluation aredocumented inreferences 4,5and11forallofthepostulated accidents.

Theoriginalshroudrepairwasdesignedtominimizestressesintroduced intotheshroudconsistent withthecriteriaprovidedsoastonotaggravate furthershroudcracking.

Theadditionofthecontactextensions, themodification tothe270'ierodandtheadditionofmodifiedlowerwedgelatcheshasaninsignificant afFectonthecomponent loadsandstresses.

InadditionanalysesincludedinReference 29havebeencompleted regarding thepotential impacttheshroudstabilizer assemblies couldhaveonverticalweldcracking.

Theresultshaveshownthatanyhoopstressinducedattheverticalweldsduetoshroudstabilizer thermalpr'eloadisnegligible.

TheoverallPage7of17 0e~I~

conclusion isthattshroudstabilizers hadnoaffectonthesoudverticalweldcrackingidentified atV9andV10.Therefore theevaluation inReference 23remainsvalid.~Theoriginalshroudrepairdesignminimized theloadingonthesupporting structures oftheshroud,suchastheshroudsupportconeandtheRPVwall,tostaywithintheoriginaldesignallowable stressesofthesestructures.

Theresultsofthisevaluation aredocumented inreferences 4,5and11forallofthepostulated accidents.

Relocating the270'owerspringassemblychangesthespacingbetweentheadjacentlowerspringassemblies.

Thechangeinspacingaffectsthenetspringcharacteristics andloaddistribution whentwospringssharethehorizontal seismicload.Analysisshowtheloadonanyonespringdoesnotexceedtheloadsusedintheoriginalstressevaluation, Reference 24.Thestressevaluation remainsvalidforthemodified270'tabilizer modification.

B.5.1.1RimehaalzshThemodifications addingthecontactextensions andmodifiedlowerwedgelatchesh'avenoaffectontheseismicanalysis.

Relocating thelowerspringaffectstheoriginalseismicanalysis.

Supplemental seismicanalysiswasmadeusingthesamemethodology andcriteriaaswasusedintheoriginalseismicanalysis.

Thechangesinthespacingbetweenlowerspringsandaffectstheeffective springcharacteristics whentwospringssharethehorizontal seismicloads.Springslessthan90'partincreasetheeffective springconstantandspringsgreaterthan90'endtolowerthespringconstant.

Equivalent springconstants weredetermined fortheboundingconditions andadditional seismiccalculations weremadetodetermine loadsanddisplacements (Reference 24).Theindividual springloadsdonotexceedtheloadsusedintheoriginalstressevaluation (Reference 25)andthecalculated displacements remainacceptable (PartB.2.1).B6A4H~IGBThedesignshallnotadversely affectthenormalflowofwaterintheannulusregion,orthenormalbalanceofflowinthisregion.Thedesignshallnotadversely restricttheflowofwaterintotherecirculation suctioninlet.B61AUHNoneofthethreemodifications adversely affectthenormalflowofwaterintheannulusregion,orrestricttheflowinanywaythatwouldadversely affectnormalbalanceofflowinthisregion.Thedesigndoesnotadversely restricttheflowofwaterintotherecirculation suctioninlet.B.7Bwzgazy.RwzatheZramluzeQZ2QIC81:InputstotheEOPcalculations, suchasbulksteelresidualheatcapacityandreduction ofreactorwaterinventory shallbeaddressed basedonrepairhardwaremassandwaterdisplacement.

IB.7.1Z~zgcmy.~m~ggZzm~ig~)nTheadditionofthespringcontactextensions andnewlatcheshaveaninsignificant affectontheEOPcalculations, suchasbulksteelresidualheatcapacityandreduction ofreactorwaterinventory sincethequantityofsteeladdedisnegligible ascomparedtothemassandvolumeoftheexistingshroudrepairhardwareandreactorinternals.

Page8of17 O.V0 Thedesignoftherepairshallaccountfortheaffectsofirradiation relaxation utilizing end-of-life fluenceonthematerials.

B81RUWEII RcoBTheoriginaldesignoftherepairaccountsfortheaffectsofirradiation relaxation utilizing end-of-life fluenceonthematerials.

Inaccordance withReference 1,thedesignconsiders anEnd-of-Life preloadrelaxation fortheupperandlowersprings.Theradiation levelislessthanthelimitcontained intheUFSAR.Thebasisforthisisdocumented inreference 11(designbasisforreference 1).Thecontactextension hasapositivespringloadedclampingforcearoundthelowercontact.Theinitialinstallation clampingforceisnotrequiredtokeepthepartcapturedorfortheparttoremainfunctional.

Radiation relaxation mayreduce,butwillnoteliminate thepositiveclampingload.Apostulated reduction intheinitialclampingloadduetoradiation relaxation isnotaconcernbecausetheextension piecesarecapturedinalldirections asdiscussed inPartB.4.1andanyamountofpositiveclampingloadwillpreventfreemovementorrandomvibrations oftheextension pieces.Apositivespringforceinthelatchisachievedbycompressing thelatchpriortoinsertion intotheholewithinthelowerwedge.Apostulated reduction intheinitialcompression loadduetoradiation relaxation isalsonotaconcernforthelatchesastheyarecapturedbyrecessedareasinthewedgeandthelowerspring.B9TimbaltychoKdtcria):

Therepairhardwareshallconsidertheeffectsofthermalcyclesfortheremaining lifeoftheplant.AnalysisshalluseoriginalplantRPVthermalcyclediagrams.

ThedesignshallassumeanumberofthermalcyclesequaltoorgreaterthanthenumberassumedintheoriginalRPVdesign.Alternatively, thermalcyclesdefinedbyactualplantoperating datamaybeemployediftechnically justified.

Usingthisthermalcycleinformation repaircomponents andtherepairedshroudshallbeevaluated forfatigueloadingalongwithanyotherdesignvibratory loads.B91XhezmalCychz Theoriginalshroudrepairhardwareanalysisconsidered theeffectsofthermalcyclesfortheremaining lifeoftheplantasdocumented inReference 5.Theanalysisconsidered thermalexpansion forthevaryingtemperatures andmaterialcombinations oftheshroud,shroudsupportcone,reactorvesselandtheshroudrepairstabilizers fornormalandupsetthermalconditions.

Thestressesresulting fromthethermalcycleshavebeenevaluated byafatigueanalysis.

Theresultsshowthatitseffectonfatiguelifeoftheplantisnegligible.

Thethreemodifications haveaninsignificant effectonpreviousfatigueanalysis.

TheanalysisprovidedinReference 30hasevaluated themodifiedlowerwedgelatchesfortheircapability towithstand loadingconditions duetothermaldifferential verticaldisplacements betweentheRPVandthestabilizer lowerspring.Theanalysisconcluded thatfornormalplantthermalcyclesaswellastransient thermalcycles(lossoffeedwater event),thenewlatcheswhenconsidering themostprobableloadingconditions willhandlethesethermalcyclessatisfactorily foratleasttheremaining plantlife.Theremovaloftheclearance betweenthetoggleboltsandtheshroudsupportconewillassurethatthedifFerential verticaldisplacements arelimitedtothedesignvaluesusedintheReference 30analysis.

Page9of17

'k Thedesignshallrecognize theuseofexistingandanticipated waterchemistry controlmeasuresforBWRsandshallconsidertheaffectsofneutronfluxonanymaterials usedintherepair.B.10.1Sincethematerials forthethreemodifications arethesameaswasusedfortheinstalled shroudrepairhardware, existingandanticipated waterchemistry controlmeasuresandtheaffectsofneutronfluxonthematerials havebeenaddressed andwillhavenoeffectontherepairhardware.

B.11L~~KIhl:Repairhardwaremechanical components shallbedesignedtominimizethepotential forloosepartsinsidethevessel.Thedesignrepairshallusemechanical lockingmethodsforthreadedconnections.

Allpartsshallbecapturedandheldinplacebyamethodthatwilllastforthedesignlifeoftherepair.B~IThemodifiedstabilizer assemblyhasbeendesignedtominimizethepotential forloosepartsinsidethevessel.Thedesignrepairusesmechanical lockingmethods(suchascrimpedjamnuts)forthreadedconnections.

Allpartsarecapturedandheldinplacebyamethodsuchaspinning,staking,springretainers, interference fits,andcrimpingthatwilllastforthedesignlifeoftherepair.Thelowercontactextension iscapturedinalldirections ontheexistinglowerspringassembly.

Thelowercontactextension isa"U"shapedpartwhichfitsaroundtheexistinglowercontact.Stepsattheendsofitslegsextendunderthelowercontacttopreventaxialmovement.

Atangtowardsthetopfitsinthegapbetweenthelowercontactandthelowerspringtopreventhorizontal movement.

Apositivespringforcefromthelegskeeptheparttightandpreventrandomvibrations.

Thespringforceisnotrequiredtoensuretheextension issecuredtotheexistinglowercontact.Apositivespringforceinthelatchisachievedbycompressing thelatchpriortoinsertion intotheholewithinthelowerwedge.Thelatchesarecapturedbyrecessedareasinthewedgeandthelowerspringsotheycannotbecomealoosepart.LmmEachGcauxbdhztheRepaizZxmzm:Specialtooling/equipment isbeingprovidedthatwillbetestedandpersonnel willbetrainedonfullscalemockupstoassureadequatecontrolsexisttominimizethepotential forvesselinternals damageorlooseparts.Protective shieldshavebeendesignedthatcanbeinstalled asneededtoprotecttheFeedwater Sparger,CoreSprayLineandtheRecirculation nozzles.NMPCandGEinstallation procedures/travelers willbeusedtoestablish ForeignMaterialExclusion (FME)controls.

Alltoolsandequipment usedintheVesselandSpentFuelPoolwillbeproperlysecured.B.12IaquxthuhuemKdhzig:Therepairdesignshallbesuchthatinspection ofreactorinternals, reactorvessel,ECCScomponents andrepairhardwareisfacilitated.

Theinstalled repairhardwareshallnotinterfere withrefueling operations andshallpermitservicing ofinternalcomponents.

Allpartsshallbedesignedsothattheycanberemovedandreplaced.

Thisistoprovidefullaccesstotheannulusareaforotherpossiblefutureinspections and/ormaintenance/repair activities thatmayprovenecessary inthefuture.Page10of17

Noneofthethreemodifications affecttheaccessforinspections.

Allpartshavebeendesignedsothattheycanberemovedandreplaced.

CuximKdtezia):

Therepairdesignshallbereviewedforcrevicestoassurethatcriteriaforcrevicesimmunetostresscorrosion crackingacceleration aresatisfied.

B.13.1Qyg~Theselection ofthematerials forthemodification hardwareisthesameastheoriginalhardwareandassuresthatcriteriaforcrevicesshowntobeimmunetostresscorrosion crackingacceleration aresatisfied.

B14M&xinhKribxe}:Allmaterials usedshallbeinconformance withtheBWRVIPrequirements.

B14.1IHatcriah Materials forthethreemodifications havethesamerequirements astheoriginalshroudrepairhardwareandareinconformance withtheBWRVIPrequirements.

B.15{Cribxig:

Thedesignedrepairshallminimizetheneedforfutureinspections andmaintenance oftherepaircomponents.

Thedesignedrepairshallminimizetherequirement forfutureinspections oftheaffectedshroudjoints.B.15.1Thestabilizer assemblies including thethreemodifications arecurrently inspected undertheNMP1Augmented Inservice Inspection Program(LDCRNo.1-94-ISI-009, Rev.3).B16ImtaE&III.

JmmKdbxig:Tooling/equipment usedforinstallation ofrepaircomponents shallbeevaluated inaccordance withReference 9andshallconsiderthefollowing:

HeavyloadsShutdownSystemStatus(N+1)RiggingHoleCuttingMethodB.16.1gi~~iI11~i~Themodifiedstabilizer assemblies havethesameinstallation requirements astheoriginalstabilizer assemblywiththeexception thataspecialprocedure (Reference 28)wasdeveloped andperformed toPageIIof17 0

lensuretheclearances werVFemoved betweenthetoggleboltsandtheholesontheshroudsideofthesupportcone.Thisprocedure ensuresthatthetierodsremaintightandarerestoredtotheiroriginaldesignmechanical preload.Noholecuttingisrequiredforeithermodification.

Theinstallation activities associated withtheproposedmodifications wereevaluated inaseparatesafetyevaluation (Ref.26).8.17ExhfingReaderInhraah(Czitezi;9:

Thedesignshallnotrelyonexistingreactorinternals orcomponents tocarryloadsthathaveexperienced crackingintheindustry(e.g.shroudheadboltlugs,stubtubes).B.17.lExhiiagRuat'abnmh Noneofthethreemodification relyonexistingreactorinternals orcomponents tocarryloadsthathaveexperienced crackingintheindustry(e.g.shroudheadboltlugs,stubtubes).Page12of17

'N~e C.Couldtheproposedchangeoractivityincreasetheprobability ofoccurrence ofanaccidentpreviously evaluated intheSAR?No.Theaffectedplantsystemsandcomponents willbecapableofperforming theirintendedfunctions withthethreecoreshroudstabilizer modifications installed.

Thesemodifications restoretheshroudrepairstabilizers totheirintendeddesigncondition.

Asthemodifications arebeingprovidedtotheplant'ssafety-related designrequirements, theprobability ofacomponent failureisnotincreased.

Thethreemodifications imposeanegligible changetotheplantoperating conditions.

Neithermodification willinteractwithanycomponent assumedtoinitiateanaccidentintheUFSAR.Norwillthefailureorpresenceofthemodifications initiateanaccidentevaluated intheUFSAR.2.Couldtheproposedchangeoractivityincreasetheconsequences ofanaccidentevaluated previously intheSAR?No.Thecalculated PeakCladTemperature (PCT)willremainbelow2200'F,andallstructures, systemsandcomponents (SSC)usedtomitigatethe(radiological) consequences oftheaccidents intheSARareindependent ofthethreeproposedmodifications, andthus,theconsequences oftheaccidents willnotbeaffected.

TheabnormaleventsintheUFSARthatpotentially couldbeaffectedbytheinstallation ofthestabilizers wereevaluated, andtheyremainunchanged.

Thethreeproposedmodifications imposenochangetotheplantoperating conditions, andthus,thereisnoaffectonanyLOCAandtransient analyses.

LOCA-Radiological analysisisbasedontheplant'sengineered safetyfeatures(ESF)functioning withindesignparameters, andtheradioactive materialsourceterms.Thethreemodifications willnotadversely affectanyESF,andthus,theESFfunctions willnotbeaffected.

Theradioactive materialsourcetermsarebasedontheregulatory limitPCTof2200'F.AsthePCTforNineMilePointIwillremainbelowthisregulatory limit,thesourcetermswillnotbeaffected.

Therefore, theconsequences oftheLOCA-Radiological analysiswillnotchange.TheMSLBanalysisreleaseislimitedbythecapacityoftheMSLFlowRestrictors, andusesUFSARallowables forsourceterms.Asthethreemodifications willnotaffecteitherofthese,theconsequences oftheMSLBanalysiswillnotchange.Seismicanalyses(Ref.6)showthatthestabilizers willremainfunctional following anearthquake 3.Couldtheproposedchangeoractivityincreasetheprobability ofoccurrence ofamalfunction ofequipment important tosafetyevaluated previously intheSAR?No.Thethreemodifications aredesignedandconstructed assafetyrelatedcomponents.

Noadverseequipment interactions willbecreatedbyinstalling thethreemodifications.

TheInstallation Processes andToolingwillnotadversely effectanyinternalcomponents important tosafetydiscussed intheSAR.Therefore, theprobability ofequipment malfunctions isnotincreased.

4.Couldtheproposedactivityincreasetheconsequences ofamalfunction ofequipment important tosafetyevaluated previously intheSAR?No.Theinstallation ofthethreemodifications ensuresthattheshroudstabilizer assemblies willperformtheirintendedfunctions.

Thus,consequences ofamalfunction ofequipment important tosafetyisnotincreased.

Thethreemodifications andtheshroudstabilizers performapassivefunctionthatdoesnotinterface withanyPage13of17 0

equipment thatisutomitigatetheradiological consequences ofamalfunction intheUFSAR.Theeffectsoftheshroudrepairstabilizer assemblies ontheconsequences ofpotentially affectedtransients arenegligible.

Asthestabilizer assemblies, including thethreemodifications, donotadversely affectequipment "Important toSafety,"theconsequences ofalltransients willnotchange.TheInstallation Processes andToolingwillnotadversely eFectanyequipment important tosafety,asdiscussed previously.

Therefore, thereisnoincreasetotheconsequences ofcomponent malfunctions.

5.Couldtheproposedactivitycreatethepossibility ofanaccidentofadifferent typethananyevaluated previously intheSAR.No.Thestabilizers, including thethreemodifications, aredesignedtothestructural criteriaspecified'in theNineMilePoint1UFSAR.Alloftheloadsandloadcombinations specified intheUFSAR,thatarerelevant'to thecoreshroud,havebeenevaluated, andarewithindesignallowables.

Thestabilizers, including Thethreemodifications, donotaddanynewoperational/failure modeorcreateanynewchallenge tosafety-related equipment orotherequipment whosefailurecouldcauseanewtypeofaccident.

Inaddition, thestabilizers orthethreemodifications donotcreateanynewcomponent/system interactions orsequenceofeventsthatleadtoanewtypeofaccident.

Ithasbeenpostulated thatifacoreshroudhada360'rackandaMSLBaccidentoccurred, theuppershroudandthetopfuelsupportcouldlift.Ifthetopfuelsupportlifteds'ufficiently, thetopsofthefuelbundlescouldmove(shift),whichmightpreventthecontrolbladesfromcompletely inserting (partialscram).Thiseventwouldbeanaccidentofadifferent'type.

However,thecoreshroudstabilizers wouldlimittheshroudfrommoving,andthus,preventthetopfuelsupportfromlifting.Theproposedchangestothelowerspring,theadditionofthelowerextensions andnewmodifiedlatcheshavenoaffectontheabilityofthestabilizer toperformthisfunction.

Thethreemodifications alsoensurethatthebarrelsectionoftheshroudbetweenweldsH5andH6Aandthecoresupportdisplacements arelimitedduringaMSLBorrecirculation LOCAwhencombinedwithanearthquake.

Therefore, themodifications donotincreasetheprobability ofoccurrence ofanaccidentofadiFerenttypethananyevaluated previously intheSAR.6.Couldtheproposedactivitycreatethepossibility ofamalfunction ofequipment important tosafetyofadifferent typethananyevaluated previously intheSAR.No.Thestabilizers, including thethreemodifications, structurally replacetheshroudhorizontal welds.Thethreemodifications includethesamedesignfeaturesastheas-installed stabilizers.

Allequipment assumedtooperateinthetransient

analyses, andthesafety-related structures, systemsandcomponents willnotbeadversely affectedbythestabilizers, including thethreemodifications.

Allcomponents interacting withthestabilizers willperformtheirintendedfunctions.

Thestabilizers, including thethreemodifications, donotincreasechallenges toorcreateanynewchallenge toequipment.

Thestabilizers, including thethreemodifications, donotcreateanynewsequenceofeventsthatleadtoanewtypeofmalfunction.

Therefore, thepossibility ofadiFerenttypeofcomponent malfunction thanevaluated intheSARisnotcreated.7.DoestheproposedactivityreducethemarginofsafetyasdefinedinthebasisforanyTechnical Specification.

No.TheTechnical Specifications Bases,theUFSAR(including theshroudrepairdesignbasisdocuments listedintheUFSAR)andtheNRCsafetyevaluation (SE)oftheNMP1shroudrepairwerereviewed.

TheUSFARandtheNRCSEdefinetheacceptance limitsforcalculated displacements

/stressesasthe"designallowable" displacement

/stresses.

Thatis,neithertheUSFARnortheNRCSEdefinethesafetymarginasthedifference betweenthePage14of17 00 previously calculat&edisplacements

/stressesandthedesignaiiowables.

Therefore, increases indisplacements

/stressesasaresultoftheproposedmodifications willnotreducethemarginofsafetyasdefinedbytheUSFARandtheNRCSE,providedthecalculated displacements/stresses remainlessthantheoriginaldesignallowables.

Theanalysiscompleted forthe270'ierodmodification, thelowerspringcontactmodification andthelowerwedgelatchmodification demonstrated thattheoriginalshroudrepaircalculated reactorinternals andrepairhardwarestressesarebounding, therefore themarginofsafetyisnotreduced.Theanalysisfortheproposedmodifications alsoindicatethatthecalculated maximumcoresupporttemporary (0.85")andpermanent (0.48")horizontal displacements increased.

Theseincreases donotreducethemarginofsafetyasdefinedabove,becausethedisplacements remainbelowthedesignallowable temporary (1.49")andpermanent (0.67")displacements.

Thisevaluation hasinvestigated modifications totheshroudrepairstabilizers atNineMilePoint1whichwillrestorethemtotheirintendeddesignfunction.

Themodifications includerelocating alowerspringassemblytoproperlybearagainsttheRPV,addingextensions toassurethespringcontactsontheshroudextendbeyondweldH6Aandinstalling newlatcheswhicharemoretolerantofdifferential verticaldisplacement.

Additionally newinstallation requirements wereimplemented toensure'the tightness ofthestabilizer assemblies.

Theplantlicensing baseshavebeenreviewed.

Thisreviewdemonstrates thatthesemodifications canbeinstalled (1)withoutanincreaseintheprobability orcons'equences ofanaccidentormalfunction previously evaluated, (2)withoutcreatingthepossibility ofanaccidentormalfunction ofanewordifferent kindfromanypreviously evaluated, (3)andwithoutreducingthemarginofsafetyinthebasesofaTechnical Specification.

Therefore, installation ofthesethreemodifications donotinvolveanunreviewed safetyquestion.

1.GE-NESpecification:

25A5583,Rev.2,"ShroudRepairHardware, DesignSpecification" 2.GE-NESpecification:

25A5586,Rev.1,"ShroudRepairCode,DesignSpecification" 3.UFSAR,Rev.12,NineMilePoint14.GE-NEDocument:

24A6426,Rev.1,"ReactorPressureVesselStressReport"5.GE-NE-B13-01739-04, Rev.0,"ShroudRepairHardwareStressAnalysis" 6.GE-NE-B13-01739-03, Rev.0,"SeismicDesignReportofShroudRepairforNineMilePoint1NuclearPowerPlant"7.NRCGenericLetter94-03,July25,1994,"Intergranular StressCorrosion CrackingofCoreShroudsinBoilingWaterReactors" 8.NiagaraMohawkProcedure:

Nl-MMP-GEN-914, "LiRingofMiscellaneous HeavyLoads"9.GE-NESpecification:

386HA852, "ReactorServicing Tools"Pagel5of17

10.GE-NEDocument:

~DO-10909, Rev.7,"SAPG07,StaticDynamicAnalysisofMechanical andPipingComponents byFiniteElementMethod"GE-NEDocument:

DRFB13-01739, "NineMilePoint1ShroudStabilization" 12.GE-NEProcedure:

NM-SM-TP&P-04, "EDMActuators" 13.NiagaraMohawkProcedure:

Nl-ODG-11, "OutageSafetyAssessment" 14.NiagaraMohawkProcedure:

NIP-OUT-01, "Shutdown Safety"15.16.GE-NE"PostInspection Plan"GE-NESpecification:

21A1104,Rev.0,"Specification forReactorPressureVessel"17.18.BWROGVIPCoreShroudRepairDesignCriteria, Rev.1,September 12,1994GE-NESpecification:

25A5584,Rev.1,"Fabrication ofShroudRepairComponents" 19.20.GE-NEDrawing:237E434,Rev.5,"ReactorVesselLoadings" GEDrawingGE-NESpecification:

383HA718, ThermalCycles,ReactorVesselandNozzle,Description BasisandAssumptions 21.GE-NE-A0003981-1-13, Rev.1,"Performance ImpactofShroudRepairLeakageforNMPI",I2/15/9422.NiagaraMohawkDocument:

SO-EOP-M018, 23.GE-NE-B13-01739-05, Rev.1,SAFETYEVALUATION, GECoreShroudRepairDesign24.Supplement 1,GENE-B13-01739-03, Rev.0,NineMilePoint1,SeismicAnalysis, CoreShroudRepairModification 25.Supplement 4,GENE-B13-01739-04, NineMilePoint1,ShroudRepairHardwareStressAnalysis26.27.28.NMPCSafetyEvaluation No.95-007Rev.1,NineMilePoint'1,CoreShroudRepairInstallation.

GENE-B13-0173940, ShroudRepairAnomalies, NineMilePointUnit1,RFO14.NMP-SHD-003, LowerWedgeLatchReplacement andTieRodTorqueChecks.29.GENE-523-B13-01869-043, Assessment oftheVerticalWeldCrackingontheNMP1Shroud,April1997.30.GENEB13-01739-22, DesignReportforImprovedShroudRepairLowerSupportLatches.31.NRCSafetyEvaluation oftheNMP1CoreShroudRepairDated3/31/95.Page16of17

.00 32.NRCSafetyEvaluateRelatedtoModifications toCorrectShroudRepairDeviations, Dated3/3/97.Page17of17 ENCLOSURE 5.--DESIGNREPORTFORIMPROVEDSHROUDREPAIRLOWERSUPPORTLATCHES~..9704100242.

ENCLOSURE6 INSPECTION HISTORY I

KineMilePointUnit1InvesselVisualInspection SummaryofInspections Performed Refueling Outage'97Thefollowing identifies theinvesselvisualinspections duringthe1997refueling outage:"A"corespraypiping,welds,andbrackets(attachment welds)"B"corespraypiping,welds,andbrackets(attachment welds)Therewerenorelevantindications noted:Upperspargers"A"and"C"lookingatthespargers, spargerwelds,including theteeboxwelds,nozzles,nozzleweldsandbrackets(attachment) welds.Lowerspargers"B"and"D"lookingatthespargers, spargerwelds,including theteewelds,nozzles,nozzleweldsandbrackets(attachment) welds.Twoindications wererecorded(1)crackatnozzle23Aandoneonnozzle26Abothindications wereobservedonpreviousdat'a.Thereisnoapparentdifference inthecracklengthRom1995until1997.Allofthesteamdryer,banksandskirts,liftinglugs.Closeattention toclips,lowerstiffener, andareaswithpreviousindications asnotedbelow:Bank2,Clip5Bank2,Clip2LockingChannelat225'ank2,LowerStiffener, 1"HoleBank4,Clip5Thepreviously identified indication wasnotedwithnogrowthorchange.Thepreviously identified indication wasnotedwithnogrowthorchange.Thepreviously identified indication wasnotedwithnogrowthorchange.Thepreviously identified indication wasnotedwithnogrowthorchange.Thepreviously identified indication wasnotedwithnogrowthorchange.

J Examination ofthemoistureseparator showednonewindications andnogrowthorchangeinindications locatedonthe102standpipe bracket.Examinedbolting,wedgesandverifiedgeneralcleanliness.

SIIA09-IDTC 1245norecordable indications notedSIIA09-IDTC 3645oneindication wasnotedandrecordedonthedrytubeshaftjustbelowthecollar.Evaluated variousareasduringexamination ofallcomponents withinthevesselthisoutage.Allfeedwater

spargers, endbrackets, pins,wedgeblocksandQowholeswereexaminedwithnoindications noted.Inaddition, theblendradiusofallfourfeedwater nozzleswereexaminedandfoundacceptable.

ChuL2aiah Locatedat180degrees,77"downthevesselwall.Severalaccessible corelocations wereinspected fordebris,erosioncorrosion andseatingsurfaces.

(wXivirfo97.v~

ENCLOSURE 7AFFIDAVIT (GE)

P1 GeneralElectricCompanyI,GeorgeB.Stramba~beingdulysworn,deposeandstateasfollows:(1)IamProjectManager,Regulatory

Services, GeneralElectricCompany("GE")andhavebeendelegated thefunctionofreviewing theinformation described inparagraph (2)whichissoughttobewithheld, andhavebeenauthorized toapplyforitswithholding.

(2)Theinformation soughttobewithheldiscontained intheGEproprietary reportsGE-NE523-B13-01869-043, Assessment oftheVertical8'eldCraclangontheNMPIShroud,Revision0,ClassIII(GENuclearEnergyProprietary Information),

datedApril1997,GENEB13-01739-40, ShroudRepairAnomalies NineMilePointUnitI,RFOI4,Revision0,ClassIII(GENuclearEnergyProprietary Information),

datedApril1997,andGENEB13-01739-22, DesignReportforImprovedShroudRepairLowerSupportRetainers, Revision0,ClassIII(GENuclearEnergyProprietary Information),

datedApril1997.Theproprietary information isdelineated bybarsmarkedinthemarginadjacenttothespecificmaterial.

(3)Inmakingthisapplication forwithholding ofproprietary information ofwhichitistheowner,GEreliesupontheexemption

&omdisclosure setforthintheFreedomofInformation Act("FOIA"),

5USCSec.552(b)(4),

andtheTradeSecretsAct,18USCSec.1905,andNRCregulations 10CFR9.17(a)(4),

2.790(a)(4),

and2.790(d)(1) for"tradesecretsandcommercial orfinancial information obtainedRomapersonandprivileged orconfidential" (Exemption 4).Thematerialforwhich'xemption fromdisclosure isheresoughtisall"confidential commercial information",

andsomeportionsalsoqualifyunderthenarrowerdefinition of"tradesecret",withinthemeaningsassignedtothosefermsforpurposesofFOIAExemption 4in,respectively, ecvC'2171QCC'.9~v~,704F2d1280 (DCCir.1983).(4)'omeexamplesofcategories ofinformation whichfitintothedefinition ofproprietary information are:aInformation thatdiscloses aprocess,method,orapparatus, including supporting dataandanalyses, whereprevention ofitsusebyGeneralElectric's competitors withoutlicenseRomGeneralElectricconstitutes acompetitive economicadvantage overothercompanies; GBS-97-3-ahunp1 l.docAffidavit PagoI

v'14'vVv~>i+los~y~svIe1v+VV~b.Information winch,ifusedbyacompetitor, wouldreducehisexpenditure ofresources orimprovehiscompetitive positioninthedesign,manufacture,

shipment, installation, assurance ofquality,orlicensing ofasimilarproduct;c.Information whichrevealscostorpriceinformation, production capacities, budgetlevels,orcommercial strategies ofGeneralElectric, itscustomers, oritssuppliers; d.Information whichrevealsaspectsofpast,present,orfutureGeneralElectriccustomer-funded development plansandprograms, ofpotential commercial valuetoGeneralElectxic; e.Information whichdiscloses patentable subjectmatterforwhichitmaybedesirable toobtainpatentprotection.

Theinformation soughttobewithheldisconsidered tobeproprietary forthereasonssetforthinbothparagraphs (4)a.aud(4)b.,above.(S)Theinfozmation soughttobewithheldisbeingsubmitted toNRCinconfidence.

Theinformation isofasortcustomazily heldinconfidence byGE,andisinfactsoheld.Theinformation soughttobewithheldhas,tothebestofmyknowledge andbelief,consistently beenheldinconfidence byGE,nopublicdisclosuxe hasbeenmade,anditisnotavailable inpublicsources.Alldisclosures tothirdpartiesincluding anyrequiredtraxisxxiittals toNRC,havebeenmade,ormustbemade,pursuanttoregulatory provisions or'roprietaxy agreements whichprovideformaintenance oftheinfozxnation inconfidence.

Itsinitialdesignation aspropzietazy information, andthesubsequent stepstakentopreventitsunauthorized disclosure, areassetforthinparagraphs (6)and(7)following.

(6)Initialapprovalofproprietary treatment ofadocumentismadebythemanageroftheoriginating component, thepersonmostlikelytobeacquainted withthevalueandsensitivity oftheinformation inrelationtoindustryknowledge, Accesstosuchdocuments withinGEislimitedona"needtoknow"basis.(7)Theprocedure forapprovalofexternalreleaseofsuchadocumenttypically requiresreviewbythestaffmanager,projectmanager,principal scientist orotherequivalent authority, bythemanagerofthecognizant marketing function(orhisdelegate),

andbytheLegalOperation, fortechnical content,competitive effect,anddetermination oftheaccuracyoftheproprietary designation.

Disclosures outsideGEarelnnitedtoregulatory bodies,customers, andpotential customers, andtheiragents,suppliers, andlicensees, andotherswithalegitimate needfortheinformation, andthenonlyinaccordance withappropriate regulatory provisions orproprietaxy agreements.

(8)Theinformation identified inparagraph (2),above,isclassified asproprietary becauseitcontainsdetailedresultsofanalytical models,methodsandprocesses, GBS-97-3-ahmpl l.doc~Affidavit Page2

.41 including computercodes,whichGEhasdeveloped andappliedtoperformevaluations ofindications inthecoreshroudfortheBWR.Thedevelopment andapprovaloftheBWRShroudRepairProgramwasachicvcdatasignificant cost,ontheorderofonemilliondollars,toGE.Thedevelopment oFtheevaluation processcontained intheparagraph (2)documentalongwiththeinterpretation and,application oftheanalytical resultsisderived&omthccxtcnsivc cxpcricncc databasethatconstitutes amajorGEasset.(9)Publicdisclosure oftheinformation soughttobewithheldislikelytocausesubstantial harmtoGE'scompetitive positionandforeclose orreducetheavailability ofprofit-making opportunities.

'Iheinformation ispartofGEscomprehensive BWRsafetyand'technology base,anditscommercial valueextendsbeyondtheoriginaldevelopment cost.Thevalueofthetechnology basegoesbeyondtheextensive physicaldatabaseandanalytical methodology andincludesdevelopment oftheexpntisetodetermine andapplytheappropriate evaluation process.Inaddition, thetechnology.

baseincludesthevaluederived&omproviding analysesdonewithNRC-approved methods.Theresearch, development, engineering, analytical andNRCreviewcostscompriseasubstantial investment oftimeandmoneybyGE.Theprecisevalueoftheexpertise todeviseanevaluation processandapplythecorrectanalytical methodology isdifBculttoquantify, butitclearlyissubstantial.

GE'scompetitive advantage willbelostifitscompetitors areabletousetheresultsoftheGEexperience tonormalize orverifytheirownprocessoriftheyareabletoclaimanequivalent understanding bydemonstrating thattheycanarriveatthesameorsimilarconclusions.

Thevalueofthisinformation toGEwouldbelostiftheinformation weredisclosed tothepublic.Makingsuchinformation available tocompetitors withouttheirhavingbeenrequiredtoundertake asimilarexpenditure ofresources wouldunfairlyprovidecompetitors withawindfall, anddepriveGEoftheopportunity toexerciseitscompetitive advantage toseekanadequatereturnonitslargeinvestment indeveloping theseveryvaluableanalytical tools.GBS-97-3-ahmp11.doc AQidavitPage3

~0 tlt-r(tJ<4(PsaJC(aswfII'0ftV(tst(flltV(V(o~STATEOFCALIFORNIA

))ss:COUNTYOFSANTACLARA)GeorgeB.Stramback, beingdulysworn,deposesandsays:Thathehasreadtheforegoing a6idavitapdthemattersstatedthereinaretrueandcorrecttothebestofhisknowledge, information, andbelief.ExecutedatSauJose,Cahfomia, this~dayof1991.orgeB.trambackGeneralElectricCompanySubscribed andswornbefore methis7~~dayof1997.otaryPublic,StateofCQKACNOOomnMeP)it3RQg.SektCheCeely

&COaaSISIIOet20,3M GBS-97-3-a&

mp11.doeAfBfhvitPage4s

GeneralElectricCompanyAIFIDAVXX'GeorgeB.Stramback, beingdulysworn,deposeandstateasfollows:(1)IamProjectMazuzgcr, Regulatory

Services, GeneralElectricCompany("GE")andhavebeendelegated thefunctionofreviewing theinfozmauon described inpazagraph (2)whichissoughttobewithheld, andhavebeenauthonzed toapplyforitswithholding.

(2)Thcinformation soughttobcwithheldiscontained intheGEproprietary drawingsReactorModification!Installation Drawing,107E5679, Revision7,andthosedrawingslistedintheattachment.

Thesedocuments, takenasawhole,constitutes aproprietary compilation ofinfozmation, someofitalsoindependently proprietary, preparedbyGeneralElectricCompany.Theindependently proprietazy elementsthataxcdrawingsaremarkedasproprietar information.

(3)Inmakingthisapplication forwithholding ofproprietazy information ofwhichitistheowner,GEreliesupontheexemption Romdisclosure setforthintheFxeedomofInformation Act("FOIA"),

5USCSec.552(b)(4),

andtheTradeSecretsAct,18USCSec.1905,andNRCregulations 10CFR9.17(a)(4),

2.790(a)(4),

and2.790(d)(l) for"tradesecretsandcommercial orfinancial infozmation obtained&omapersonandpzivilcged orconfidential" (Exemption 4).Thematerialforwhichexemption

&undisclosure isheresoughtisall"confidential commercial information",

andsomepoztionsalsoqualifyunderthenarrowerdefinition of"tradesecret",withinthemeaningsassignedtothosetermsforpurposesofFOIAExemption 4in,respectively, VC'9dWCC'.199),

z~Q704F2d1280 (DCCir.1983).(4)Someexamplesofcategories ofiufozznation whichQtintothcdefinition ofproprietary information are:.a.Infozmation thatdiscloses aprocess,method,orapparatus, including suppoiting dataandanalyses, whereprevention ofitsusebyGeneralElectric's competitors withoutlicenseRomGeneralElectricconstitutes acompetitive economicadvantage overothercompanies; b.Infozmation which,ifusedbyacompetitor, wouldzeducehisexpezuHture ofresources orimprovehiscompetitive positioninthedesign,manufactuze,

shipment, installation, assurance ofquality,orlicensing ofasimilarproduct;GBS-97-3-afNMP12.doc Af5davitPage1 NI c.Information whichrevealscostorpriceinformation, production capacities, budgetlevels,orcommercial stxategies ofGeneralEcctric,itscustomers, oritssuppliers; d.Information whichrevealsaspectsofpast,present,orfutureGeneralElectriccustomer-Sided development plansandprograms, ofpotential commercial valuetoGeneralHectric;e.Information whichdiscloses patentable subjectmatterforwhichitmaybedesirable toobtainpatentprotection.

Theinformation soughttobcwithheldisconsidered tobeproprietary forthereasonssetforthinbothparagapbs (4)a.,(4)b.and(4)e.,above.Theinformation soughttobcwithheldisbeingsubmitted toNRCincon6dencc.

Theinformation isofasortcustomarily held.incon6dcncc byGE,andisinfactsoheld.Theinformation soughttobewithheldhas,tothebestofmyknowledge andbelief,consistently beenheldinconfidence byGE,nopublicdisclosure hasbeenmade,anditisnotavaihbleinpublicsources.Alldisclosures tothirdpazticsincluding anyrequiredtraasmittals toNRC,havebccnmade,ormustbomade,pursuanttoregulatory pzovisions orpropzietary agreements whichprovideformaintenance oftheinfozznation incon6dence.

Itsinitialdesignation asproprietary information, andthesubsequent stepstakentopreventitsunauthorized disclosure, azeassetfozthinparagraphs (6)and(7)following.

hitialapprovalofpxopxzctazy treatxnent ofadoemM:ntismadebythczmuugczoftheoriginating component, thepersonmostlikelytobeacquainted withthevalueandsensitivity oftheiafozxnaxion inrehtiontoindustryknowledge.

Accesstosuchdocuments withinGEishmitedona"needtoknow"basis.'Iheprocedure forapprovalofexternalreleaseofsuchadocumenttypically xectuircs reviewbythestaffmanager,projectmanager,pxincipal scicxxtist orotherequivalent authority, bythemanagerofthccognizant marketing Rncnon(orhisdelegate),

andbytheLegalOperation, fortechnical content,competitive eEcct,anddctemhetion ofthcaccuracyofthepxopxictazy designation.

Disclosures outsideGEarelimitedtoregulatory bodies,custormm, andpotential customers, andtheiragents,suppliers, andlicensees, andotherswithalegitimate need.forthcinformation, andthenonlyinaccordance withappzoyciate regulatory provisions orproprietary agrccmcxxts.

Theinfozxnation identified inparagraph (2),above,isclassiGcd aspxopxietaxy becauseitconstitutes acon6dential compilation ofinformation, including detaileddesigndrawingresultsofahardwaredesignmodiGcatioa (stabilizer fortheshroudhorizontal welds)intetMled tobeinstalled inareactortoresolvethereactorpressurevesselcoreshroudweMcrackingconcern.Thedevelopment andapprovalofthisGBS-97-3wfNMp) 2.docA6idavitPage2

designmodification utilmxisystems,components, andmodelsandcomputercodesthatweredeveloped atasiyCificant costtoGE,ontheorderofseveralhundredthousanddollars.Thedetailedresultsoftheanalytical models,methods,andprocesses, including computercodes,andconclusions

&omtheseapplications, represent, asawhole,anintegrated processorapproachwhichGEhasdeveloped, andappliedtothisdesignmodification.

Thedevelopment ofthesupporting processes wasatasignificant additional costtoGE,inexcessofamilliondollars,overandabovethelargecostofdeveloping theunderlying individual proprietary rcportanddrawingsinformation.

(9)Publicdisclosure oftheinfoanation soughttobewithheldislikelytocausesubstantial harmtoGE'scompetitive positionandforeclose orreducetheavailabiTity ofprofit-mahng opportunities.

Theinformation ispartofGE'scomprehensive BWRsafetyandtechnology base,anditscommercial valueextendsbeyondtheoriginaldevelopment cost.Thevalueofthetechnology basegoesbeyondtheextensive physicaldatabaseandanalytical methodology andincludesdevelopment oftheexpertise todetermine andapplytheappropriate evaluation process.Inaddition, thetechnology baseincludesthevaluederivedRomproviding analysesdonewithNRC~vedmethods.tTheresearch, development, etgineering, analytical andNRCreviewcostscompriseasubstantial investment oftimeandmoneybyGE.'IheprecisevalueoftheLyeztisetodeviseanevaluation processandapplythecorrectanalytical methodology isdiKculttoquantify, butitclearlyissubstantiaL GE'scompetitive advantage willbelostifitscompetitors areabletousetheresultsoftheGEexperience tonormallize orverifytheirownprocessoriftheyareabletoclaimanequivalent understanding bydemonstrating thattheycanarriveat.thesame,orsimilarconclusions.

Thevalueofthisinformation toGEwouldbelostiftheinformation weredisclosed tothepublic.Makingsuchinformation availabIe tocompetitors withouttheirhavingbeenrequiredtoundertake asimilarexpenditure ofresources wouldunSurlyprovidecompetitors withawindfall, anddepriveGEoftheopportunity toexerciseitscompetitive advantage toseekanadequatereturn,on,itslargeinveshnent indeveloping theseveryvaluableanalytical tools.*GBS-97-3-aSMP12.doc AfDdavitPago3

eeCIt,cJI2IuJD'WII'Ixsc.asxxt,IC.~~II~CD~CDSTATEOFCALIFORNIA

))ss:CORIYOFSANTACUBA)Geog@B.Strarnback, beingduly~rn@Posesandsay:Thathchasreadtheforegoing aQbhvitandthemLttcrsstaredthcremaretrueandcorrecttothebestofhishnowIcdgc, inforrnations andbelief.ExeurtcdatSanJose,California, this'~dayofl997.rgeB.backGeneralElectricCompanySubsenbexi sutisexoxubefoxexutehis

~XtbsfofI997:.otazyPublic,Stateo4l5hCoasgym~OIt~~NcCevPC~a~~~sgesnN3Caeet

~amatpeeaOctm

~GBS-97-3-aSMP12.doc Af6davitPage4 t

nremvi'bi88:18i'pl GEBNRTECHNOLOGY

~~,'.j-P.26/26ATTACHMENT

~Drawin112D6546, Rev.3,TieRod,SpringAssembly112D6573, Rcv.3,UpperSupportAssemblyGB&97-3wfNMP12.doc A6idavitPagoS 1J CATEGORY1.REGULATINFORMATION DISTRIBUTION.

STEM(RIDS)ACCESSION

'NBR:9704100242 DOC.DATE:

97/04/08NOTARIZED:

YESDOCKETIFACIL:50-220 NineMilePointNuclearStation,Unit1,NiagaraPowe05000220AUTH.NAMEAUTHORAFE'LIATIONMCCORMICK,M.J.

NiagaraMohawkPowerCorp.RECIP.NAME RECIPIENT AFFILIATION DocumentControlBranch(Document ControlDesk)

SUBJECT:

Forwardsproprietary

&non-proprietary reptsfromGEreGL94-03,"Intergranular StressCorrosion CrackinginBWRs."Listofrepts,encl.Encls withheld,per 10CFR2.790(b)(i).

DISTRIBUTION CODE:AP01DCOPIESRECEIVED:LTR ENCLSIZE:TITLE:Proprietary ReviewDistribution

-PreOperating License&Operating RENOTES:RECIPIENT IDCODE/NAME PD1-1LAHOOD,DINTERNAL:

ACRSOGC/HDS3EXTERNAL:

NRCPDRCOPIESLTTRENCL11111110RECIPIENT IDCODE/NAME PD1-1PDLECENTER01COPIESLTTRENCL11110DUENNOTETOALL"RIDS"RECIPIENTS:

PLEASEHELPUSTOREDUCEWASTE.TOHAVEYOURNAMEORORGANIZATION REMOVEDFROMDISTRIBUTION LISTSORREDUCETHENUMBEROFCOPIESRECEIVEDBYYOUORYOURORGANIZATION, CONTACTTHEDOCUMENTCONTROLDESK(DCD)ONEXTENSION 415-2083TOTALNUMBEROFCOPIESREQUIRED:

LTTR7ENCLP

~~~W~I$'vCf,kII,f CATEGORY2REGULATORY INFORMATION DISTRIBUTION SYSTEM(RIDS)ACCESSION NBR:9704100242 DQC.DATE:9'7/04/08 NOTARIZED:

YES.DOCKETFACIL:50-220NineMilePointNuclearStationsUnitiiNiagaraPowe05000220AUTH.NAMEAUTHORAFFILIATION "MCCORMICK'.

J.NiagaraMohawkPowerCorp.'-~RECIP.NAMERECIPIENT AFFILIATION DocumentControlBranch(Document ControlDesk)

SUBJECT:

Forwardsproprietary 5non-proprietary reptsfromGEreGL94-03'Intergranular StressCorrosion CrackinginBMRs."Listofrepts>encl.Enclswithheldi per1OCFR2.7'VO(b)(i).DISTRIBUTION CODE:AP01DCOPIESRECEIVED:

LTRENCLSIZE:TlTLE:Proprietary ReviewDistribution

-PreOperating License';cNOTES:l+38Operating RRECIPIENT lDCODE/NAME PDi-1LAHOQDiDINTERNAL:ACRSQGC/HDS3EXTERNAL:

NRCPDRCOPIESLTTRENCL1111.111010RECIPIENT IDCODE/NAME PDi-1PDFILECENTER01COPIESLTTRENCL110Y,DCENOTETOALL"RIDS"RECIPIENTS:

PLEASEHELPUSTOREDUCEWASTE.TOHAVEYOURNAMEORORGANIZATION REMOVEDFROMDISTRIBUTION LISTSORREDUCETHENUMBEROFCOPIESRECEIVEDBYYOUORYOURORGANIZATION, CONTACTTHEDOCUMENTCONTROLDESK(DCD)ONEXTENSION 415-2083TOTALNUMBERQFCOPIESREQUIRED:

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NiAGARAMOHAWKGENERATI0NBUSiNESSCROUPMARTINJ.McCORMICK JR.P.E.VicePresident NuciearEngineering NINEMILEPOINTNUQI.EARBTATIONJLAKE ROAD.P.O.BOX63.LYCOMING, NEWYORK13093/TELEPHONE (3I5)349.2660FAX(3(5)349-2605April8,1997NMPIL1200U.S.NuclearRegulatory Commission Attn:DocumentControlClerkWashington, DC20555RE:NineMilePointUnit1Docket50-220

Subject:

GenericLetter94-03"Intergranular StressConosionCracking(IGSCClinBoiling8'aterReactors" Gentlemen:

BylettersdatedJanuary6,1995andJanuary23,1995,NiagaraMohawkPowerCorporation (NMPC)submitted anapplication forrepairstotheNineMilePointUnit1(NMP1)coreshroud.Theshroudrepairsanduseofstabilizer assemblies (tierods)weresubmitted asanalternate totherequirements oftheASMECode,SectionXI,asallowedby10CFR50.55a (a)(3)(i).

Thestaffprovidedapprovaloftheproposedalternate repairbyletterdatedMarch31,1995.Theapprovalletterandattachedsafetyevaluation requiredNMPCtosubmitre-inspection plansfortheshroudandrepairassemblies priortothenextrefueling outageplannedfor1997.ByletterdatedFebruary7,1997,NMPCsubmitted plansforre-inspection ofthecoreshroudverticalweldsandrepairassemblies inaccordance withthecriteriaprovidedbythe"BWRVesselandInternals Program"(BWRVIP)documentBWRVIP-07.

Duringthe1997refueling outage,NMPCconducted coreshroudverticalweldinspections pertheapproveddocuments andobservedverticalweldcrackingwhichexceededthescreening criteria.

Additionally, inspections ofthefourtierodassemblies foundthetierodnutstohavelostsomepreloadandidentified damagetothelowerwedgeretainerclipsonthreetierods.Furtherdetailsoftheasfoundconditions areprovidedinEnclosures 1and2.ByphonecallsonMarch20,1997andApril2,1997,NMPCinformedthestaffoftheinspection findingsandindicated thatanalysisoftheverticalweldcrackingandrestoration planoftheshroudtierodassemblies wouldbesubmitted totheNRCpriortorestartoftheunit.Thisletterandtheattachedenclosures providerootcause,corrective actionsandthefinaldesigndocumentation whichestablishes theacceptability oftheasfoundverticalweld9704100242 970408PDRADOCK05000220P'DR

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