ML17059C550

Rev 0 to MPR-1966(NP), NMP Unit 1 Core Shroud Vertical Weld Repair Design Rept.

ML17059C550
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Site:	Nine Mile Point
Issue date:	01/31/1999
From:	MCCURDY H W MPR ASSOCIATES, INC.
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ML17059C551	List: ML17059C550 ML18040A360
References
MPR-1966(NP), MPR-1966(NP)-R, MPR-1966(NP)-R00, NUDOCS 9902100204
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ENCLOSUKE31%1NEMHEPOINTUI.'GTl(NMPl)CORESHROUDVERTICALWELDREPAIRDESIGNREPORTNON-PROPMKTARYVERSION9902i00204990203'DRADOCK05000220PPDR 4~4'J raqMpRASSOCIATESINC.ENGINEERSNineMilePointUnit1CoreShroudVerticalWeldRepairDesignReportMPR-1966(NP)Non-ProprietaryVersionRevision0January1999Preparedby:H.illiamMurdyReviewedby:-aiB.%wannerApprovedby:WilliamR.SchmidtPrincipalContributorsH.WilliamMcCurdy,MPRAssociatesCraigB.Swanner,MPRAssociates,BenjaminR.Lane,MPRAssociatesQUALITYASSURANCEDOCUMENTThisdocumenthasbeenprepared,reviewed,andapprovedinaccordancewiththeQualityAssurancerequirementsof10CFR50AppendixB,asspecifiedintheMPRQualityAssuranceManual.320KINGSTREE'TALEXANDRIA,VA22314-3230703.519-0200FAX:703-519-0224

TableofContents1IntroductionandSummary.~.~~....~.........~......~..~..~1-11.1Introduction1.2Summary............~~.1.2.1RepairOverview.......................................1-11.2.2StructuralandDesignEvaluations,.......................1-11.2.3SystemEvaluations..........1.2.4MaterialandFabrication1-21-21.2.5Pre-ModificationandPost-ModificationInspection......2Background2.1ReactorInternalsDesignBases...........~....~........2.2FunctionalRequirements1-22-12-13DescriptionofRepair.............~...~~...........~......~3-13.1DesignObjectives.3.2DesignCriteria...........3-13-13.3DescriptionofRepairComponentsandDesignFeatures....4StructuralandDesignEvaluation.~~...~~~..~~.....~....4.1DesignLoadsandLoadCombinations4.2AnalysisModelsandMethods4.3RepairHardwareEvaluation~4.3.1RepairHardwareStructuralEvaluation4.3.2FlowInducedVibration4.3.3RadiationEffects.3-14-14-14-14-14-14-24.4ShroudEvaluation......4-34.5ImpactonTie-RodRepair....4-3MPR-1966(NP)Revision0n

4.6LoosePartsConsiderations.444.7InstallationCleanliness~445SystemsEvaluation.......................................5-15.1BypassFlowforNormalOperation.5.2BypassFlowforOtherConditions..~~~~~~~~~5-25.3DowncomerFlowandOtherEffects............~..,........5-26MaterialsandFabrication................................6-16.1MaterialSelection6-16.2MaterialProcurementSpecifications6.3MaterialFabrication~~~~~~~~~~~~~~6-27Pre-ModificationandPost-Modificationinspection7.1Pre-ModificationInspection7.2Post-ModificationInspection~~~~~~~~~~~~~7-1~~~~~~~~717.2.1PriortoRPVReassembly.7.2.2DuringSubsequentRefuelingOutages~~~~~~~~~~~~~7-18References..............................................8~MPR-1966(NP)Revision0

Tables4-1CoreShroudVerticalWeldRepairDesignLoadsandLoadCombinations............................................464-2LimitingStressesintheRepairClampAssembly...............4-74-3ShroudStressRatioSummary..............................4-86-1RepairClampMaterials...................................6-3MPR-1966(NP)Revision01V

Figures1-1NineMilePointUnit1CoreShroudWelds...~...~~.~..~..~...1-31-2NineMilePointUnit1Assembly.~~...~..1-3NineMilePointUnit1Assembly1-4NineMitePointUnit1ClampAssembly1-5NineMilePointUnit1Assembly....~..~~ExplodedViewofV4VerticalWeldClamp~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~InstalledV4VerticalWeldClamp~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ExplodedViewofV9/V10VerticalWeld~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~InstalledV9V/10VerticalWeldClamp~~~~~~~~~MPR-1966(NP)Revision0

introductionandSummary1.1IntroductionThisreportdocumentsthedesignofthecoreshroudverticalweldrepairfortheNineMilePointNuclearStationUnit1(NMP-1).ThereportfollowstheguidelinesinBWRVIP-04[1],"GuideforFormatandContentofCoreShroudRepairSubmittals."Asummaryoftherepairdesign,supportingevaluations,material,fabricationandinspectionrequirementsisprovidedinthisreport.1.2SummaryTheNMP-1coreshroudverticalweldrepairaddressesthecrackingofverticalweldsV4,V9andV10(seeFigure1-1).TherepairisnotincludedundertheASMEBoilerandPressureVesselCodeSectionXIdefinitionforrepairorreplacement.Rather,therepairisdevelopedasanalternativerepairpursuantto10CFR50.55a(a)(3).Assummarizedbelow,therepairsatisfiestherequirementsspecifiedinBWRVIP-02[2],"CoreShroudRepairDesignCriteria."Therepairisconsistentwiththecurrentplantlicensingbasisandensuresthattheshroudwillsatisfyitsoperationalandsafetyfunctions.1.2.1RepairOverviewAsshowninFigures1-2through1-5,therepairconsistsofrepairclampswhichholdtheshroudtogetheratthefailedverticalweldlocations.TherepairdesignspecificationisprovidedinReference3.1.2.2SfrucfuralandDesignEvaluationsAssummarizedbelow,therepairsatisfiesthestructuralrequirementsspecifiedinReferences2,3and4.~Ridl-TPpIIpdIpIIIdcriteriafortherepairhardware.Inparticular,althoughtherepairisnotconsideredanASMEB&PVCoderepair,therepairsatisfiestheDesignbyAnalysisstressandfatiguecriteriaoftheASMEBoiler&MPR-1966(NP)Revision0

PressureVesselCode,SectionIII,SubsectionNG[4].SeeSection4.3ofthisreportforadditionalinformationontherepairassemblystructuralevaluation.~Shroud-ThestressesintheshroudresultingfromtherepairarewithinthestressallowablesofSectionIII,SubsectionNGoftheASMEBoiler&PressureVesselCode[4].SeeSection4.4ofthisreportforadditionalinformationontheshroudstructuralevaluation.1.2.3SystemEvaiuafionsTheleakagethroughthefailedverticalweldswiththerepairclampsinstalledwascalculatedandfoundtobewithintheacceptancecriteria.Thisincludedtheleakagethroughtherepairclampshroudattachments.SeeSection5ofthisreportforadditionalinformationontheseevaluations.1.2.4MaferiaiandFabricationThematerialsspecifiedforuseintherepairassembliesareresistanttostresscorrosioncrackingandhavebeenusedsuccessfullyintheBWRreactorcoolantsystemenvironment.TherepairassembliesarefabricatedfromsolutionannealedType304or316stainlesssteelorsolutionannealedTypeXM-19stainlesssteel.Noweldingispermittedinthefabricationorinstallationoftherepair,andspecialcontrolsandprocessqualificationsareimposedinthefabricationoftherepairtoassureacceptablematerialsurfaceconditionsaftermachining.SeeSection6ofthisreportforadditionalinformationonrepairhardwarematerialsandfabrication.1.2.5Pre-ModificationandPost-ModificationInspectionsTheinspectionstobeperformedtosupporttherepairaresummarizedbelow.Pre-ModificationInsection-Priortoinstallationoftheshroudrepair,visualinspectionswillbeperformedtosupporttherepairinstallation.TheseinspectionsarelistedinSection7.1.PostModificationInsection-Priortoreactorpressurevesselreassembly,visualinspectionswillbeperformedtoverifytheproperinstallationofrepair.ThescopeoftheseinspectionsisdiscussedinSection7.2.InspectionoftheshroudandtherepairinfuturerefuelingoutageswillbebasedontheBWRVIP-07[6],"GuidelinesforReinspectionofCoreShrouds."MPR-1966(NP)Revision01-2

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ShroudLockingScrew"t14VerticalWeldV4PlateCutoutlnShroudlWallLeftBayonetEccentric'8RightBayonetEccentricThreadedPln199SNPRASSOCIATESU.S.PATENTPENONG5BMPR)slOl~OS00)l0/l1/N(AD)Figure1-2.NineMilePoint-Unit1ExplodedViewofV4VerticalWeldClampAssembly

V4VerticalWeldLoctdngScrewShroudRightBayonetEccentricLeftBayonetEccentricV4PlateThreadedPinldMPR/tieOllOl0$/21/$4(JSI)Figure1-3.NineMilePoint-Unit1InstalledV4VerticalWeldClampAssemblyI998IIPRASSOCAIESU.S.PAIEIITPEIIOIIIC

ShroudIV9jV10VerticalWeldLockingScrewCutoutinShroudWallV9/V10PlateLeftBayonetEccentricThreadedPinRightBayonetEccentricFAHMPR/N$01~01ol/c4/ssIAu)Figure1%.NineMilePoint-Unit1ExplodedViewofV9/V10VerticalWeldClampAssemblyPCI99SMPRASSOCNTESU.S.PAIENrPENQNG

V4VerticalWeldShroudLockingScrewRightBayonetEccentricLeftBayonetEccentricV9jV10PlateThreadedPinQMPRtlnOl~C4IN/4I/nIAJTFigure0-5.NineMilePoint-UnitIInstalledV9/V10VerticalWeldClampAssemblyPC199SIJPRASSOCIATESIAS.PATEtITPEIITNNO

2Backround2.1ReactorinternalsDesignBasesFromtheNMP-1FinalSafetyAnalysisReport(Updated)[5],thereactorinternalsaredesignedto:1.Providesupportforthefuel,steamseparators,dryers,etc.,duringnormaloperationandaccidentcondition.2.Maintainrequiredconfigurationsandclearancesduringnormaloperationandaccidentconditions.3.Circulatereactorcoolanttocoolthefuel.4.Provideadequateseparationofsteamfromwater.2.2FunctionalRequirementsfortheRepairThefunctionalrequirementsfortherepairareidentifiedinBWRVIP-02[2].Therequirementsare:1.StructurallyreplacetheverticalweldsandmaintainthestressesoftheaffectedshroudcylinderwithinASMESectionIIIstressallowablesforallloadcombinationsandservicelevels.2.Limitcoolantleakagethroughthecrackedverticalweldstoacceptablelevelsfornormaloperationandtransientplantconditions.NotethattheNMP-1plantdoesnotrequireafloodablevolumetobemaintainedforaccidentconditionstoprovidefoxadequatecorecooling.MPR-1966(NP)Revision02-1

DescritionofReair3.1DesignObjectivesThefunctionoftherepairistostructurallyreplacefailedV4,V9andV10(seeFigure1-1)coreshroudwelds.3.2.DesignCriteriaTherepairisdevelopedasanalternativerepairpursuantto10CFR50.55a(a)(3).TherepairisconsistentwithandmeetsthecriteriadevelopedbytheBoilingWaterReactorVesselandInternalsProject,asstatedinBWRVIP-02[2].ThedesignspecificationfortherepairisprovidedinReference3.TherepairisdesignedtosatisfythestructuralrequirementsofSectionIII,SubsectionNG,"CoreSupportStructures,"oftheASMEBoiler&PressureVesselCode[4].3.3.DescriptionofRepairComponentsandDesignFeaturesTherepairclampisillustratedinFigures1-2through1-5:~Figures1-2and1-3showexplodedandinstalledviewsoftherepairclampforverticalweldV4.~Figures1-4and1-5showexplodedandinstalledviewsoftherepairclampforverticalweldsV9andV10.Eachrepairclampconsistsofaclampplateandtwobayoneteccentric/threadedpinassemblies.Theclampisinstalledinthrough-wallholesmachinedintheshroudbyEDMprocessesoneachsideoftherepairedverticalweld.Therepairweldclamptransmitstheshroudhooppressureforcewhichwouldnormallybetransmittedthroughtheshroudverticalweld.Thestructuralloadpathisfromtheshroudthroughabayoneteccentric/threadedpintotheclampplateandthroughtheclampplateandotherbayoneteccentric/threadedpinassemblybacktotheshroud.MPR-1966(NP)Revision03-1

Theinstallationstepsfortherepairclampareasfollows:~Therepairclampisassembledwith:Thepinsretractedwiththeirflangesurfacesflushwiththeplateinnersurfaces.Thebayoneteccentricsrotatedtothepositionwherethepinaxisisalignedwiththecenterofthe1.563inchradiusportionoftheshroudhole.FortheV4clamp,therightbayoneteccentric/threadedpinassemblyisinsertedintheclampplateaftertheclampplatehasbeenmovedinpositionbetweenthecoreshroudandthecorespraypipe.~Thepinsarethreadedinwarduntiltheirflangesextendbeyondtheshroudinsidesurfaces.~Thebayoneteccentricsarerotatedtobringthepinshaftsintothe1.265inchradiusportionoftheshroudholeandintocontactwiththeshroudholesurfaces.~Thebayoneteccentricsarefixedintopositionwiththelockingscrewswhichextendintomatingslotsintheeccentrics.Thelockingscrewsarefixedinpositionbycrimpingattwolocations.~Thepinsarethreadedoutwardtobringtheirflangesurfacesintocontactwiththeshroudinnersurfaceandtorquedtoprovideaspecifiedpreload.Anallowableof50percentforrelaxationofpreloadduetocombinedthermalandirradiationeffectsisprovidedinthepreloaddetermination.~Thepinsarelockedinpositionbycrimpingtotheeccentricattwolocations.Notethattheclampinstallationprovidesthefollowingfeatures:Theleakagepathsthroughtheshroudholesareeffectivelysealedbytheextendedsealringportionsoftheclampplatewhicharemachinedtoaradiusequaltotheshroudradiusandseatontheshroudsurface.Thepreloadbetweenthepinflanges,theclampplateandtheshroudpreventsrelativedisplacementbetweentherepairclampandshroudduetoflowinducedvibrationloading.PerReference10,clamploadingduetoshroudvibrationisnegligible.MPR-1966(NP)Revision03-2

TherepairdesignhasconsideredcrevicesandtheirimpactonstresscorrosioncrackingbyusingmaterialswhicharehighlyresistanttoIntergranularStressCorrosionCracking(IGSCC).Thematerial'sIGSCCresistanceisverifiedbytestingperrequirementsofASTMA262PracticeE.SeeSection6ofthisdesignsummaryreportforfurtherdiscussiononmaterialsandfabrication.MPR-1966(NP)Revision03-3

StructuralandDesinEvaluation4.1DesignLoadsandLoadCombinationsTheloadsandloadcombinationsarelistedintheDesignSpecificationfortherepair[3].TheseloadsandloadcombinationsaresummarizedinTable4-1.Acombinationofhandcalculationsandfiniteelementanalysesareusedtodefinethedesignloads.ThecoreshroudpressuredifferentialslistedintheDesignSpecificationareusedinthedesignoftherepair.Theonlydesignloadsofsignificancetotherepairarethoseduetodifferentialpressureacrosstheshroudandthoseduetodifferentialthermalexpansionbetweentheshroudandrepairclamp.4.2AnalysisModelsandMethodologyAnalysismodelsandmethodsusedtoevaluatetherepairhardwareandexistingstructuresarediscussedbelow.Acombinationofhandcalculationsandfiniteelementanalyseswereusedtoevaluatetherepairhardwareandexistingstructures.Three-dimensionalfiniteelementanalysesusingtheANSYScodewereusedtodeterminethestructuralresponseoftheshroud.Handcalculationswereusedintheevaluationsoftherepairhardware.4.3RepairHardwareEvaluation4.3.7RepairHardwareStructuralEvaluationTherepairhardwaresatisfiesthestructuralcriteria.Inparticular:~TheDesignbyAnalysisstressandfatiguecriteriaoftheASMEBoiler8r,PressureVesselCode,SectionIII,SubsectionNGaresatisfied.MPR-1966(NP)Revision04-1

~Themaximumfatigueusageintherepairassemblyduetothermalexpansion(includingstartupandshutdown)loadsoccurinthebayonetholeintherepairclampplate.Thefatigueusageatthislocationislessthan3%.~Themaximumfatigueusageintheshroudattherepairattachmentsisnegligible.~Thefatigueusagefromflowinducedvibrationisnegligible.~ThereisnonetsectionyieldingforServiceLevelsA/8loads.TheratioofthecalculatedstresstotheallowablestressforthelimitingloadcasesissummarizedinTable4-2fortheclampcomponents.4.3.2FlowInducedVibrationTherepairclampswereanalyzedtoensurethatreactorcoolantflowwouldnotinduceunacceptablevibration.Thefollowingbasicapproachwasfollowedtoprovideresistancetoflow-inducedvibrationloading:~Theflow-inducedloadperunitareaoftherepairclampisconservativelycalculatedbasedonadifferenceinpressureequaltoone-timestheflowvelocityheadacrosstheclampplate.~Theclampispreloadedbytighteningthethreadedpinstoaforcewhichisgreaterthanthesumoftheflow-inducedloadplusthepressureleadactingtoejecttheclampfromtheshroud.Theminimumpreloadisincreasedbyafactorof50%toaccountforrelaxationduetocombinedthermalandirradiationeffects.Thisapproachprovidesassurancethatnoclampdisplacementsandnoalternatingstresswillresultfromtheflow-inducedvibrationloading.NotethatperTableB.6.1ofReference10,theshroudvibrationamplitudeisonlyonemilandthereforehasanegligibleeffectontherepairclampvibration.4.3.3RadiationEffectsTheeffectsofradiationwereconsideredintheselectionoftherepairmaterialsandfabricationprocesses.Relaxationduetothermalandirradiationseffectswasconsideredinthedeterminationofthreadedpinpreload.AsdiscussedinSection6,allmaterialsusedintherepairhavebeenusedsuccessfullyforyearsintheBWRenvironment.MPR-1966(NP)Revision04-2

4.4ShroudEvaluationThestresses1nthecoreshroudwereevaluatedtothestresscriteriaoftheASMEB&PVCode,SectionIII,SubsectionNG[4].TheratioofcalculatedshroudstressestotheallowablestressforthelimitingloadcasesissummarizedinTable4-3.Asshowninthetable,theshroudcancarrytheappliedloadswithinthecodestressallowablesforalldefinedloadings.4.5ImpactonTie-RodRepairThesafety,stressandseismicanalysesforthecoreshroudtie-rodrepair(References7,8and9)werereviewedandevaluatedtodetermineifthereisanyimpactfromtheverticalweldrepair.Resultsofthereview/evaluationare:NospecificdiscussionofrequirementsfortheshroudverticalweldswasfoundinReferences7,8and9.However,itisclearthatthedesignandtheanalysesofthetie-rodrepairarebasedontheshroudretainingacylindricalconfigurationintheeventofcrackingintheverticalwelds.Accordingly,theverticalweldrepairisrequiredtopreservethecylindricalshroudconfigurationforallappliedloadsandloadcombinations.AsidentifiedinSection2.2above,thisisoneofthefunctionalrequirementsfortheverticalweldrepair.Noallowanceforcoolantleakagethroughcrackedverticalweldsisconsideredinthesafetyanalysisforthetie-rodrepair(Reference7).Therefore,theverticalweldrepairisrequiredtolimitverticalweldleakage,incombinationwithotherleakagesources,towithinacceptablelevelsforallplantconditions.ThisisafunctionalrequirementfortheverticalweldrepairasstatedinSection2.2above.PerReference9,theseismicfuelloadsaretransmitteddirectlythroughthetopguideorcoresupportplateringstothetie-rodradialrestraints.Therefore,itisthestiffnessoftheseringsandnotthestiffnessoftheshroudcylindersthataffectsthefuelseismicresponse.Forashroudcylinderwithfullycrackedverticalweldsandendconditionsthatprovidenolateralshearrestraint,thelateralstiffnesswouldbereduced.Sinceshroudstiffnessisaparameterintheshroudseismicmodel,thisreductioncouldimpacttheseismicanalysisresults.However,thispotentialimpactisnotsignificantsinceforalloftheseismiccasesconsideredinSection5ofReference9,theH1-H2andH4-H5shroudcylindershavehingedconnectionstotheadjacentcylinders.ThishingedconnectionMPR-1966(NP)Revision04-3

providessheartransferbetweentheshroudcylindersandpermitstheshroudcylinderstoretaintheiruncrackedmomentofinertiaandrotationalstiffness.Forthetie-roddesignbasisconfigurationwithaclearanceof0.75inchbetweentheshroudandthemid-supports,Reference9determinesthattherearenolateralseismicloadsappliedtotheshroudduringaseismicevent.However,withtheas-installedclearanceof0.375inchbetweentheshroudandthemid-supports,thereareseveralLevelDloadcombinationswheretherelativeseismicdisplacementatthemid-supportexceedsthe0.375inchclearance.Theresultingmid-supportloadwasevaluatedasaprimaryload,andtheloadsreactedbytheverticalweldrepairweredeterminedtobeacceptable.Basedontheabove,theverticalweldrepairhasnoimpactonthetie-rodrepairandthesupportingsafety,stressandseismicanalyses.4.6.LoosePartsConsiderationThevariouspiecesthatmakeuptherepairassembliesarecapturedandrestrainedbyappropriatelockingdevicessuchaslockingcupsandcrimping.Theselockingdevicedesignshavebeenusedsuccessfullyformanyyearsinreactorinternals.Loosepiecescannotoccurwithoutfailureofthelockingdevicesorrepairassemblycomponents.Suchlockingdevicesandthestressesinthepieceswhichmakeuptherepairclampsarewellwithinallowablelimitsfornormalplantoperation.4.7.InstallationCleanlinessAlltoolingusedforinstallationwillbeinventoriedandsubjectedtoforeignmaterialexclusionprocedureswheninthereactorvesselarea.Toolingwillbecheckedforloosepartspriortoinstallationintothecanal.Furthermore,thetoolingwillbeextensivelyfieldhardenedpriortositedeploymenttoreducethepossibilityoftoolfailuresand/orbreakswhichcouldpotentiallyresultinloosepartsremaininginthevessel.Iffailuresoccur,thepartswillberetrievedfromthereactorvesselorcavity.Foreachrepairclamp,through-thicknessholesaremachinedintheshroudsupportusingtheEDMprocess.Thisprocessresultsinaveryfinedebris(swarf'einggenerated.Thisdebrisisprimarilycomprisedofcarbon,nickel,iron,chromium,etc.,whicharetheprimaryelementscontainedintheshroudandEDMelectrodematerial.Thisswarfisflushedandvacuumedfromthecutduringthemachiningoperation,thenfilteredpriortodischargebackintothecavity.TheEDMelectrodeisdesignedtoonlygenerateswarf.Aslugisnotgeneratedastheelectrodebreaksthroughtheinsidesurfaceoftheshroud.Also,adebriscollectionsystemisMPR-1966(NP)Revision044

positionedontheshroudinsidesurfacetocollecttheEDMswarfgeneratedwhentheEDMelectrodebreaksthroughtheinsidesurfaceoftheshroud.TheEDMdebrissystemhasa10micronanda2micronfilterinseries.Eachfilterhas200sq.ft.ofeffectivesurfacearea.The10micronfilterisratedat99%efficientfor10micronsand80%efficientforjustbelow2.5microns.The2micronfilteris99%efficientfor2micronsand90to93%efficientfor1micron.Asthesefiltersareloaded,theirefficiencywillgreatlyincrease.ThetotalamountofswarfcollectedbythisEDMdebriscollectionsystemhasbeenqualified.Thedebrissystemcollectedover95%ofthedebristhatwasgenerated.Thisqualificationwasperformedwithoutaninternaldebriscup.Therefore,thetestwasconservative.ThesmallamountofswarfnotcollectedbytheEDMdebrissystemisnotdetrimentaltotheBWRsystem.'ISubsequenttocompletionoftherepairhardwareinstallationactivities,afinalvideoinspectioninthereactorvesselandcavitywillbeperformedtoverifynoforeignobjectentryduringtherepair.MPR-1966(NP)Revision04-5

Table4-1CoreShroudVerticalWeldRepairDesignLoadsandLoadCombinationsNo.EventNormalOperationUpsetNo.1UpsetNo.2EmergencyNo.1EmergencyNo.2EmergencyNo.3FaultedNo.1FaultedNo.2FaultedNo.3LoadCombination<'1't'1'<'1NormalPressure+DW+SteadyStateThermalUpsetPressure+DW+UpsetThermalUpsetPressure+DW+OBE+SteadyStateThermal"'ormalPressure+DW+DBESteamLineLOCA+DWRecirculationOutletLineLOCA+DWSteamLineLOCA+DW+DBERecirculationInletLineLOCA+DW+DBERecirculationOutletLineLOCA+DW+DBENotes:(1)LoadcombinationsasspecifiedinTable2-2ofGENE-B13-01739-04[8].(2)DW=Deadweight,LOCA=LossofCoolantAccident,DBE=DesignBasisEarthquake,OBE=OperatingBasisEarthquake.(3)Alleventsincludeflowloads.(4)OBEloadsareequivalenttoDBEloads.(5)Theonlydesignloadsfortherepairclampareexpectedtobethoseduetodifferentialpressureacrosstheshroudandthoseduetodifferentialthermalexpansionbetweentheshroudandrepairclamp.Otherloadsshallbeevaluatedtoconfirmthattheyneednotbeconsideredasdesign-basisloads.MPR-1966(NP)Revision04-6

Table4-2LimitingStressesintheRepairClampAssemblyRepairLocationLimitingStressLocationServiceLevel:ServiceConditionStresstypeStressLimitStressRatioV9orV10BayonetConnectionBayonetConnectionBayonetConnectionA:NormalOperationB:UpsetPressureB:LossofFeedwaterThermalTransientBearingBearingBearing1.0Sy0.4001.0Sy0.6041.0Sy0.636BayonetConnectionC:SteamLineBreakBearing1.5Sy0.994PlateatBayonetHoleA:NormalOperationMembranePlusBending1.5Sm0.367PlateatBayonetHoleB:UpsetPressureMembranePlusBending1.5Sm0.555V4BayonetConnectionB:LossofFeedwaterThermalTransientBearing1.0Sy0.479PlateatBayonetHoleC:SteamLineBreakMembranePlusBending2.25Sm0.915MPR-1966(NP)Revision04-7

Table4-3ShroudStressRatioSummaryRepairLocationV9orV10V4ServiceLevel:ServiceConditionA:NormalOperationB:UpsetPressureB:LossofFeedwaterTransientC:MainSteamLineBreakA:NormalOperationB:UpsetPressureB:LossofFeedwaterTransientStressTypePrimaryMembranePrimaryMembranePlusBendingPrimaryPlusSecondaryMembraneatHolePrimaryMembranePrimaryMembranePlusBendingPrimaryPlusSecondaryMembraneatHolePrimaryPlusSecondaryMembranePlusBendingPrimaryPlusSecondaryMembraneatHolePrimaryMembranePrimaryMembranePlusBendingPrimaryMembranePrimaryMembranePlusBendingPrimaryPlusSecondaryMembraneatHolePrimaryMembranePrimaryMembranePlusBendingPrimaryPlusSecondaryMembraneatHolePrimaryPlusSecondaryMembranePlusBendingPrimaryPlusSecondaryMembraneatHoleStressLimitSm1.5Sm3SmSm1.5Sm3Sm3Sm3Sm1.5Sm2.KSmSm1.5Sm3SmSm1.5Sm3Sm3Sm3SmStressRatio0.200.190.410.300.290.540.660.55O.e70.460.070.080.310.110.110.410.570.49C:MainSteamLineBreakPrimaryMembranePrimaryMembranePlusBending1.5Sm2.25Sm0.170.18MPR-1966(NP)Revision04-8

5.2BypassFlowforOtherConditionsAsdiscussedinPartB.3ofReference7,therearenodetrimentaleffectsofshroudbypassfloweitheronplantanticipatedabnormaltransientsoronemergencycorecoolingsystemperformance.5.3DowncomerFlowandOtherEffectsThe'effectsoftherepairclampassemblyontheflowinthereactorvesseldowncomerregionare:~TheV4repairclampreducestheflowareainthedowncomeratthetopofthecoreshroudbyapproximately2.5percent.TheV9/VOclampswouldreducetheflowareabyalesseramountbecausetheyarepositionedatalowerelevationwherethedowncomerflowareaisgreater.~ThepressuredropassociatedwiththeV4clampisapproximately0.006psidfornormaloperationand0.044psidfortherecirculationlinebreakcondition.FortheV9/V10clamps,thepressuredropislessthanfortheV4clamp.FortheV4,V9andV10clamps,thetotalweightislessthan1000lbswhichisnegligiblecomparedtothetotalshroudweight.Thedisplacedreactorwaterinventoryislessthantwocubicfeetofwater,whichisalsonegligible.MPR-1966(NP)Revision05-2

MaterialsandFabrication6.1MaterialSelectionThematerialsspecifiedforuseintherepairclampsareresistanttostresscorrosioncrackingandhavebeenusedsuccessfullyintheBWRreactorcoolantsystemenvironment.AsshowninTable6-1,therepairclampsarefabricatedfromsolutionannealedType304or316orTypeXM-19stainlesssteel.XM-19materialisusedforallpartsexceptthelockingscrewwhereType304/316orTypeXM-19stainlesssteelisused.AsrequiredbytheDesignSpecification,allmaterialsspecifiedforuseintheshroudrepairareinaccordancewithASMEorASTMapprovedspecifications.AllmaterialshavebeenpreviouslyusedintheBWRenvironmentsimilartothatexperiencedbytherepairclamps.ThematerialsarenotsusceptibletogeneralcorrosionandareresistanttoIntergranularStressCorrosionCracking(IGSCC)inaBWRenvironment.Additionalinformationonmaterialspecification,procurementandfabricationrequirementsimplementedtoensurethattherepairhardwareishighlyresistanttoIGSCCisprovidedinSections6.2and6.3.MaterialpropertiesandallowablestressesforrepaircomponentsareasspecifiedintheASMEB&PVCode,SectionsIIandIII,1989EditionforClass1components.6.2MaterialProcurementSpecificationsAllhardwareisconstructedfromausteniticstainlesssteelmaterial.Weldingonthesematerialsisprohibitedbytheprocurementrequirements.Thesematerialsasprocured,arehighlyresistanttoIGSCC.NDEofmaterialusedforload-bearingmembersisperformedinaccordancewithASMECodeSectionIII,SubsectionNG-2000.Specificmaterialrequirementsaresummarizedbelowforthematerialusedintherepair.AllstainlesssteelmaterialisprocuredinaccordancewiththeapplicableASMEorASTMstandardssupplementedbythefollowing:~Type304/316alloyshave0.03%maximumcarbon.TypeXM-19alloyhas0.04%maximumcarbon.AllstainlesssteelmaterialsarefullcarbidesolutionannealedandeitherwaterorforcedairquenchedfromthesolutionannealingMPR-1966(NP)Revision06-1

temperaturesufficienttosuppresschromiumcarbideprecipitationtothegrainboundariesinthecenterofthematerialcrosssection.Solutionannealingofthematerialisthefinalprocessstepinmaterialmanufacture.ASTMA262PracticeEtestsareperformedoneachheat/lotofstainlesssteelmaterialtoverifyresistancetointergranularattackandthatanon-sensitizedmicrostructureexists(nograinboundarycarbidedecoration).Pickling,passivationoracidcleaningofloadbearingmembersisprohibitedaftersolutionannealingunlessanadditional0.010inchesmaterialthicknessisremovedbymechanicalmethods.Forothernon-loadbearingitems,metallographyat500Xisperformedonmaterialsfromeachheat,similarlyprocessed,toverifyexcessiveintergranularattackhasnotoccurred.Controlsarealsospecifiedintheprocurementdocumentstoprecludematerialcontaminationduringmaterialprocessingandhandlingfromlowmeltingpointmetals,theiralloysandcompounds,aswellassulfurandhalogens.6.3MaterialFabricationNoweldingorthermalcuttingisusedinthefabricationandassemblyoftheitems.Cuttingfluidsandlubricantsareapprovedpriortouse.Controlsarealsospecifiedtoprecludematerialcontaminationduringprocessingandhandlingfromlowmeltingpointmetals,theiralloysandcompounds,aswellassulfurandhalogens.Passivation,picklingoracidcleaningoftheitemsisprohibited.Liquidpenetranttestingafterfinalmachiningorgrindingoncriticalsurfacesisperformed.Abusivemachiningandgrindingpracticesareavoided.Machiningandgrindingprocessparametersandoperationsarecontrolled.Additionally,machiningprocessparametersincriticalloadbearingthreadedareasarecontrolled,basedonqualificationsamples,whichhavebeensubjectedtomacroscopicandmetallographicexaminationsandmicrohardnesstesting.Evaluationsincludehardnessmagnitudesanddepths,depthofseveremetaldistortion,depthofvisibleevidenceofslipplanesanddepthofcoldwork.MPR-1966(NP)Revision06-2 t

Table6-1RepairClampMaterialsParti'PlateBaonetEccentricThreadedPinV4ClamXM-19XM-19XM-19Material'"V9/V10ClamXM-19XM-19XM-19LockingScrewType304/316orXM-19@Type304/316orXM-19"'otes:(1)SeeFigures1-2and1Aforidentificationofparts.(2)Allmaterialissolutionannealed.(3)XM-19materialisusedforthelockingscrewsfortheNMP-1repairclamps.MPR-1966(NP)Revision06-3

Pre-ModificationandPost-ModificationInsection7.1Pre-ModificationInspectionThefollowingvisualinspectionswillbeperformedtosupporttherepairinstallation:TheazimuthallocationsoftheV4,V9andV10verticalweldswillbeidentifiedusingvisual,ultrasonicoreddycurrentmethods.Ifweldscannotbeidentifiedvisually,amethodforvisuallyidentifyingtheweldlocationswillbedevelopedwhichinvolvesmarkingtheshroudorindexingtotheweldfromotherinternals.FollowingidentificationoftheV4weld,measurementswillbemadetoverifythatadequateclearanceexistsbetweentheverticalweldandthecoresprayverticalpipingtoallowinstallationoftherepairclamp.TVvisualinspectionwillbeperformedattheV4,V9and/orV10verticalweldswheretheverticalrepairclampswillbeinstalledtoassurethattherearenointerferencesoradditionalcracking.Anengineeringevaluationwillbeperformedtoaddressanyinterferencesoradditionalcrackingidentified.7.2Post-ModificationInspection7.2.1PriortoRPVReassemblyProperinstallationofeachverticalweldrepairclampassemblywillbeconfirmedandrecordedbyTVvisualinspectionfromboththeinsideandoutsideoftheshroud.Theinspectionwillverif'ythatallpartsareinstalledasrequiredandnoforeignobjectsremain.Asaminimum,thefollowingareaswillbeinspected:Thetopandbottomoftherepairclamptoverifythattheclearancebetweentheplateandtheshroudsurfaceisconsistentwiththedesignclearance.Theslotsintheplateandtheeccentricstoverif'ythattheeccentricsareproperlyalignedwiththeplate.Thetopofthelockingscrewtoverifythatthelockingscrewisfullyengagedwiththeeccentric.MPR-1966(NP)Revision07-1

~Thepinliptoverifythatthepinlipareaoverlappingtheshroudinsidesurfaceisconsistentwiththedesignconfiguration.~Theaxiallocationofthethreadedpinrelativetotheeccentrictoqualitativelyverifythatthethreadedpinisengagedwiththeshroudinnerdiameter.~Thelockingscrewsandthreadedpinstoconfirmcrimping.~Afinalvideoinspectioninthereactorvesselandcavitywillbeperformedtoverifynoforeignobjectentryduringtherepair.7.2.2DuringSubsequentRefuelingOutagesInspectionoftherepairclampsinfuturerefuelingoutageswillbebasedontherequirementsinSection4.2ofBWRVIP-07[6],"GuidelinesforReinspectionofCoreShrouds."Theinspectionwillinvolvethevisualinspectionoftheoverallclampandthethreadedpin-to-eccentricandlockingscrew-to-eccentriccrimpareastoconfirmnochangefromtheirconditionduringthepost-installationinspection.InspectionfrequencywillbeinaccordancewithBWRVIP-07requirements.MPR-1966(NP)Revision07-2 0

References1.EPRIReportTR-105692,"BWRVIPVesselandInternalsProject,GuideforFormatandContentofCoreShroudRepairDesignSubmittals(BWRVIP-04),"October1995.2.EPRIReport,"BWRVIPVesselandInternalsProject,CoreShroudRepairDesignCriteria(BWRVIP-02),"Revision2,FifthDraftReport,April1988.3.MPRSpecificationNo.249014-001,"DesignSpecificationforNineMilePointNuclearStationUnit1(NMP1)CoreShroudVerticalWeldRepair,"Revision1,October12,1998.4.ASMEBoilerandPressureVesselCode,SectionIII,Division1-SubsectionNG,"CoreSupportStructures,"1989Edition.5.NineMilePointNuclearStationUnit1FinalSafetyAnalysisReport(Updated),Revision15,November1997.6.EPRIReportTR-105747,"BWRVesselandInternalsProject,GuidelinesforReinspectionofBWRCoreShrouds(BWRVIP-07),"February1996.7.NineMilePointUnit1SafetyEvaluationNumber94-080,Rev.1forModificationN1-94-003,ReactorCoreShroudRepair.8.GENE-B13-01739-04,"NineMilePointUnit1ShroudRepairHardwareStressAnalysis(NMPCCalculationNo.SO-Vessel-M028),"Revision0.9.GENE-B13-01739-03,"NineMilePointUnit1NuclearPowerStation,SeismicAnalysis,CoreShroudRepairModification(NMPCCalculationNo.SO-Vessel-M027),"Revision0.10.NEDE-13109,"OysterCreekStartupTestResults,"July1970.MPR-1966(NP)Revision08-1

ENCLOSURE4YOFNIAGARAMOHAWK10CFR50.59SAFETYEVALUTION

CORESHROUDVERTICALWELDREPAIRCLAMPSSAFETYEVALUATIONSUMMARYDI<'.SCRIPTIONtTheNMP-1coreshroudverticalweldrepairaddressesthecrackingofverticalweldsV4,V9andV10(seeFigure1-1).TherepairbasicallyconsistsofaclampwithaplatewithattachedpinswhichareinsertedintoholeswhicharemachinedbytheElectricDischargeMachining(EDM)processoneithersideoftheflawedverticalweld.Theclampsbridgeacrosstheflawedverticalweldandtransmitthepressureloadnormallytransmittedthroughtheverticalweld.TwoclampsareusedfortheV9weld,twoclampsfortheV10w'eldandoneclampisusedfortheshorterV4weld.Therepairclampscanbeinstalledoneachweldindependently,thatisanyone,twoorthreeweldscanberepairedwiththeserepairclamps.Priortothisrepairbeingutilizedasastructuralreplacementforthewelds,anNRCapprovalwillberequired.Assummarizedbelow,therepairsatisfiestherequirementsspecifiedinBWRVIP-02[1],"CoreShroudRepairDesignCriteria."Therepairisconsistentwiththecurrentplantlicensingbasisandensuresthattheshroudwillsatisfyitsoperationalandsafetyfunctions.Fordetailsoftherepairclampevaluations,whicharesummarizedbelow,seethedesignreportfortherepair,reference9.PARTA.1-GE<NERALTherepairclampdesignisillustratediriFigures1-2through1-5:~Figures1-2and1-3showexplodedandinstalledviewsoftherepairclampforverticalweldV4.~Figures1-4and1-,5showexplodedandinstalledviewsoftherepairclampsforverticalweldsV9andV10.Eachrepairclampconsistsofaclampplateandtwobayoneteccentric/threadedpinassemblies.Theclampsareinstalledinthrough-wallholesmachinedintheshroudbyEDMprocessesoneachsideoftherepairedverticalweld.Therepairweldclampstransmittheshroudhooppressureforcewhichwouldnormallybetransmittedthroughtheshroudverticalweld.Thestructuralloadpathisfromtheshroudthroughabayoneteccentric/threadedpintotheclampplateandthroughtheclampplateandotherbayoneteccentric/threadedpinassemblybacktotheshroud.Theinstallationstepsfortherepairclampsareasfollows:~Therepairclampsareassembledwith:ThepinsretractedwiththeirflangesurfacesflushwiththeplateinnersurfacesThebayoneteccentricsrotatedtothepositionwherethepinaxisisalignedwiththecenterofthelargerportionoftheshroudhole.FortheV4clamp,therightbayoneteccentric/threadedpinassemblyisinsertedintheclampplateaftertheclampplatehasbeenmovedinposition.~Thepinsarethreadedinwarduntiltheirflangesextendbeyondtheshroudinsidesurfaces.1of14

~Thebayoneteccentricsarerotatedtobringthepinshaftsintothesmallerradiusportionoftheshroudholeandintocontactwiththeshroudholesurfaces.I~Thebayoneteccentricsarefixedintopositionwiththelockingscrewswhichextendintomatingslotsintheeccentrics.Thelockingscrewsarefixedinpositionbycrimpingattwolocations.~Thepinsarethreadedoutwardtobringtheirflangesurfacesintocontactwiththeshroudinnersurfaceandtorquedtoprovideaspecifiedpreload.~Thepinsarelockedinpositionbycrimpingtotheeccentricattwolocations.Notethattheclampinstallationprovidesthefollowingfeatures:~Theleakagepathsthroughtheshroudholesareeffectivelysealedbytheextendedsealringportionsoftheclampplate,whicharemachinedtoaradiusequaltotheshroudradiusandseatontheshroudsurface.~Thepreloadbetweenthepinflanges,theclampplateandtheshroudpreventsrelativedisplacementbetweentherepairclampandshroudduetoflowinducedvibrationloading.PARTA.2-MATERIALSPARTA.2.1-MATERIALSELECTIONThematerialsspecifiedforuseintherepairclampsareresistanttostresscorrosioncrackingandhavebeenusedsuccessfullyintheBWRreactorcoolantsystemenvironment.TherepairclampsarefabricatedfromsolutionannealedTypeXM-19stainlesssteel~AsrequiredbytheDesignSpecification[2],allmaterialsspecifiedforuseintheshroudrepairareinaccordancewithASMEorASTMapprovedspecifications.AllmaterialshavebeenpreviouslyusedintheBWRenvironmentsimilartothatexperiencedbytherepairclamps.ThematerialsarenotsusceptibletogeneralcorrosionandareresistanttoIntergranularStressCorrosion'Cracking(IGSCC)inaBWRenvironment.Additionalinformationonmaterialspecification,procurementandfabricationrequirementsimplementedtoensurethattherepairhardwareishighlyresistanttoIGSCCisprovidedinA.2.2andA.2.3below.MaterialpropertiesandallowablestressesforrepaircomponentsareasspecifiedintheASMEB&PVCode,SectionsIIandIII,1989EditionforClass1components,MPR-1966[9].PARTA.2.2-MATERIALPROCUREMENTSPECII'ICATIONSAllhardwareisconstructedfromausteniticstainlesssteelmaterial.Weldingonthesematerialsisprohibitedbytheprocurementrequirements.Thesematerialsasprocured,arehighlyresistanttoIGSCC.NDEofmaterialusedforload-bearingmembersisperformedinaccordancewithASMECodeSectionIII,SubsectionNG-2000.Specificmaterialrequirementsaresummarizedbelowforthematerialusedintherepair.AllstainlesssteelmaterialisprocuredinaccordancewiththeapplicableASMEorASTMstandardssupplementedbythefollowing:~Type304/316alloyshave0.03%maximumcarbon.TypeXM-19alloyhas0.04%maximumcarbon.Allstainlesssteelmaterialsarefullcarbidesolutionannealedandeitherwaterorforcedairquenchedfromthesolutionannealingtemperaturesufficienttosuppresschromiumcarbideprecipitationtothegrainboundariesinthecenterofthematerialcrosssection.2of14 0

~Solutionannealingofthematerialisthefinalprocessstepinmaterialmanufacture.ASTMA262PracticeEtestsareperformedoneachheat/lotofstainlesssteelmaterialtoverifyresistancetointergranularattackandthatanon-sensitizedmicrostructureexists(nograinboundarycarbidedecoration).~Pickling,passivationoracidcleaningofload-bearingmembersisprohibitedaftersolutionannealingunlessanadditional0.010inchesmaterialthicknessisremovedbymechanicalmethods.Forothernon-loadbearingitems,metallographyat500Xisperformedonmaterialsfromeachheat,similarlyprocessed,toverifyexcessiveintergranularattackhasnotoccurred.~Controlsarealsospecifiedintheprocurementdocumentstoprecludematerialcontaminationduringmaterialprocessingandhandlingfromlowmeltingpointmetals,theiralloysandcompounds,aswellassulfurandhalogens.PARTA.2.3-MATERIALFABRICATIONNoweldingorthermalcuttingisusedinthefabricationandassemblyoftheitems.Cuttingfluidsandlubricantsareapprovedpriortouse.Controlsarealsospecifiedtoprecludematerialcontaminationduringprocessingandhandlingfromlowmeltingpointmetals,theiralloysandcompounds,aswellassulfurandhalogens.Passivation,picklingoracidcleaningoftheitemsisprohibited.Liquidpenetranttestingafterfinalmachiningorgrindingoncriticalsurfacesisperformed.Abusivemachiningandgrindingpracticesareavoided.Machiningandgrindingprocessparametersandoperationsarecontrolled.Additionally,machiningprocessparametersincriticalloadbearingthreadedareasarecontrolled,basedonqualificationsamples,whichhavebeensubjectedtomacroscopicandmetallographicexaminationsandmicrohardnesstesting.Evaluationsincludehardnessmagnitudesanddepths,depthofseveremetaldistortion,depthofvisibleevidenceofslipplanesanddepthofcoldwork.ThemachiningpracticesusedinthefabricationprocessfortheclampswillbequalifiedtoensurethecoldworklayeratthesurfacehasbeenmaintainedtoreducethepotentialforIGSCCinitiationsites.PART8-ANALYSISPART8.1-REPAIRDESIGNLIFECRITERIAThedesignlifeoftherepairshallbefor25calendaryears(remaininglifeoftheplantincludinglifeextension)toinclude20effectivefullpoweryears.PART8.1.1-REPAIRDESIGNLIFECONFORMANCEAllrepairhardwarehasbeendesignedfor25calendaryearstoinclude20effectivefullpoweryears.Thisincludes:~Selectionof.stainlesssteelrepairmaterialswhichhavebeensuccessfullyusedinaboiling,waterreactorenvironmentandwhichareresistanttoIGSCC.~Considerationofplanttransientsrepresentativeof20effectivefullpoweryearsofoperation(i.e.,120thermaltransientsfromstartupsandshutdownsand30scramswithlossoffeedwaterpumps.)~Considerationofradiationfluenceinducedrelaxationofrepairhardwarepreload.3of14

PART8.2-FUNCTIONALREUIREMENTSCRITERIAThefunctionalrequirementsfortherepairareidentifiedinBWRVIP-02[1].Therequirementsare:1.StructurallyreplacetheverticalweldsandmaintainthestressesoftheaffectedshroudcylinderswithinASMESectionIIIstressallowablesforallloadcombinationsandservicelevels.2.Limitcoolantleakagethroughthecrackedverticalweldstoacceptablelevelsfornormaloperationandtransientplantconditions.NotethattheNMP-1plantdoesnotrequireafloodablevolumetobemaintainedforaccidentconditionstoprovideforadequatecorecooling.PART8.2.1-FUNCTIONALREUIREMENTSCONFORMANCETherepairhardwaresatisfiesthestructuralcriteriafortherepairhardware.Inparticular:~TheDesignbyAnalysisstressandfatiguecriteriaoftheASMEBoiler8r,PressureVesselCode,SectionIII,SubsectionNGaresatisfiedfortheshroudandfortherepairclamps.Acomparisonofthecalculatedandallowablestressintensitiesfortherepairclampsisshowninthefollowingtable:4of14

LimitingStressesintheRepairClampAssemblyRepairLocationLimitingStressLocationBayonetConnectionBayonetConnectionServiceLevel:ServiceConditionA:NormalOperationB:UpsetPressureStresstypeBearingBearingStressLimit1.0Sy1.0SyStressRatio0.4000.604BayonetConnectionB:LossofFeedwaterThermalTransientBearing1.0Sy0.636V9orV10BayonetConnectionC:SteamLineBreakBearing1.5Sy0.994PlateatBayonetHolePlateatBayonetHoleBayonetConnectionA:NormalOperationB:UpsetPressureB:LossofFeedwaterThermalTransientMembranePlusBendingMembranePlusBendingBearing1.5Sm1.5Sm1.0Sy0.3670.5550.479V4PlateatBayonetHoleC:SteamLineBreakMembranePlusBending2.25Sm0.915~Themaximumfatigueusageintherepairassemblyduetothermalexpansion(includingstartupandshutdown)loadsoccurinthethreadedpins.Thefatigueusageatthislocationislessthan3%.~Themaximumfatigueusageintheshroudattherepairattachmentsisnegligible.~Thefatigueusagefromflowinducedvibrationisnegligible.CoolantleakagecriteriaandconformancearediscussedinPartsB.3,B.3.1,B.3.1.1andB.3.1.2below.PARTB.3-FLOWPARTITIONCRITERIASof14

TherepairsshallconsiderleakagethroughtherepairedverticalweldsV4,V9andV10aswellasthroughtheattachmentholesinthecoreshroud.Theleakageshallbelessthanallowableswhicharedeterminedbasedonconsiderationofleakagefromothersources(crackedhorizontalwelds,tie-rodlowerconnection,etc.).PART8.3.1-FLOWPARTITIONCONI'ORMANCETherepairdesignlimitsshroudleakagetotheallowablesdefinedinReference2forallplantoperatingconditions.Specifically,theleakageiswithinlimitsestablishedforcorebypassleakageandsteamcarry-underasdiscussedinPartB.3.1.1below.AsdiscussedinPartB.3.1.2,theeffectsofleakageoncoremonitoring,anticipatedabnormaltransients,emergencycorecoolantandfuelcyclelengtharenegligible.PART8.3.1.1-LEAKAGEFLOWEVALUATIONAsstatedinPartB.2(FunctionalRequirements(Criteria))ofthisreport,therepairisrequiredtolimitleakageofreactorcoolantthroughtherepairedverticalweldsduringnormalplantoperation.Thisincludestheleakagethroughtheverticalweldsandtheleakagethroughtheholesmachinedthroughtheshroudwallfortherepairclampinstallation.Consideringleakagefromallothersources,allowableleakagerateswereestablishedforthevertical'weldrepairasdescribedinSection6.2oftheDesignSpecification[2].Theselimitsare:~ThecombinedleakageratethroughweldsV9andV10andtheirrepairclampsshallbelessthan0.25%ofthetotalcoreflow(2%ofthecorebypassflow)fornormaldifferentialpressure.~ThecombinedleakagerateofsteamthroughweldV4anditsrepairclampshallbelessthan0.08%oftherecirculation(coreminussteam)flowfornormaldifferentialpressure.ThecalculatedleakageflowratesthroughrepairedverticalweldsV4,V9andV10aresummarizedasfollows:RepairedVerticalWeldLeakageLeakageFlowRate(gpm)RepairedWeldsCalculatedAllowableV41.6396V9andV10247337PART8.3.1.2-COREMONITORINGANTICIPATEDABNORMALTRANSIENTSEMERGENCYCORECOOLINGSYSTEMANDFUELCYCLELENGTHAsdiscussedinPartsB.3.1.3throughB.3.1.6ofReference6,theeffectofshroudleakageoncoremonitoring,anticipatedabnormaltransients,emergencycorecoolingandfuelcyclelengthareconsideredtonotbesignificant.6of14

PART8.3.1.3-CONCLUSIONTheimpactoftheleakagethroughtherepairedshroudverticalweldsonplantoperationhasbeenevaluatedasdiscussedaboveandfoundtobeacceptable.,PART8.4-FLOW-INDUCEDVIBRATIONCRITERIAEvaluationsshallbeperformedofrepairclampvibrationandwearforflow-inducedvibration.ThealternatingstressfromtherepairclampvibrationshallbelimitedtothematerialendurancestressortheASMECodeallowablestressforthenumberofvibrationcycles.PART8.4.1-FLOW-INDUCEDVIBRATIONCONFORMANCETherepairclampswereanalyzedtoensurethatreactorcoolantflowwouldnotinduceunacceptablevibration.Thefollowingbasicapproachwas'followedtoprovideresistancetoflow-inducedvibrationloading:~Theflow-inducedloadperunitareaoftherepairclampisconservativelycalculatedbasedonadifferenceinpressureequaltoone-timestheflowvelocityheadacrosstheclampplate.~Theclampispreloadedbytighteningthethreadedpinstoaforcewhichisgreaterthanthesumoftheflow-inducedloadplusthepressureloadactingtoejecttheclampfromtheshroud.Thisapproachprovidesassurancethatnoclampdisplacementsandnoalternatingstresswillresultfromtheflow-inducedvibrationloadingfornormalplantconditions.PART8.5-LOADINGONEXISTINGINTE<RNALCOMPONENTSCRITERIATheloadingandresultingstressesfortheshroudshallbeevaluatedandshowntobewithinallowables,asspecifiedinReferences1,2and3.PART8.5.1-LOADINGONE<XISTINGINTE<RNALCOMPONENTS~CONFORM*NCRThestressesinthecoreshroudwereevaluatedtothestresscriteriaoftheASMEBEcPVCode,SectionIII,SubsectionNG[3].Theshroudcancarrytheappliedloadswithinthecodestressallowablesforallloadcasesasshowninthefollowingtable.l7of14 0

ShroudStressRatioSummaryRepairLocationServiceLevel:ServiceConditionStressTypeStressLimitStressRatioA:NormalOperationPrimaryMembranePrimaryMembranePlusBendingSm0.201.5Sm0.19IPrimaryPlusSecondaryMembraneatHole3Sm0.41B:UpsetPressurePrimaryMembranePrimaryMembranePlusBendingPrimaryPlusSecondaryMembraneatHoleSm0.303Sm0.541.5Sm0.29V9orV10B:LossofFeedwaterTransientC:MainSteamLineBreakPrimaryPlusSecondaryMembranePlusBendingPrimaryPlusSecondaryMembraneatHolePrimaryMembranePrimaryMembranePlusBending3Sm0663Sm0.551.5Sm0.472.25Sm0.46A:NormalOperationPrimaryMembraneSm0.07PrimaryMembranePlusBending1.5Sm0.08PrimaryPlusSecondaryMembraneatHole3Sm0.31B:UpsetPressurePrimaryMembraneSm0.11PrimaryMembranePlusBendingPrimaryPlusSecondaryMembraneatHole1.5Sm0.113Sm0.41B:LossofFeedwaterTransientPrimaryPlusSecondaryMembranePlusBendingPrimaryPlusSecondaryMembraneatHole3Sm3Sm0.570.49V4C:MainSteamLineBreakIPrimaryMembranePrimaryMembranePlusBending1.5Sm0.172.25Sm0.188of14 0

PART8.6-SEISMICANALYSISCRITE<RIATheexistingseismicevaluationsofthecoreshroudandhorizontalweldrepairhardwareshallbereviewedtodetermineiftheverticalweldrepairhardwareneedstoaddressanyseismicloadsordisplacements.StressesforanyverticalweldrepairseismicloadingshallbecalculatedandcomparedwithallowablesasspecifiedinReferences1,2and3.PART8.6.1-SEISMICANALYSISCONFORMANCEExistingseismicevaluationswerereviewedandseveralloadingcasesidentifiedwhereaseismicloadwasappliedtotheH4-H5shroudcylinderbythemid-supportofthecoreshroudrepair.Theresultingloadsandstressesontheverticalweldrepairclampswereevaluatedandfoundtobeacceptable.PART8.7-ANNULUSFLOWDISTRIBUTIONCRITERIAAnalysesshallbeperformedtoshowthattherepairdesigndoesnotadverselyaffectthein-vesselflowcharacteristicsinthedowncomerannulusregion.PART8.7.1-ANNULUSFLOWDISTRIBUTIONCONFORMANCETheevaluationoftheeffectsoftherepairclampassemblyontheflowinthereactorvesseldowncomerregiondeterminedthat:~TheV4repairclampreducestheflowareainthedowncomeratthetopofthecoreshroudbyapproximately2.5percent.TheV9/V10clampswouldreducetheflowareabyalesseramountbecausetheyarepositionedatalowerelevationwherethedowncomerflowareaisgreater.~ThepressuredropassociatedwiththeV4clampisapproximately0.006psidfornormaloperationand0.044psidfortherecirculationlinebreakcondition.FortheV9/V10clamps,thepressuredropislessthanfortheV4clamp.Theflowarearestrictionandpressuredropincreaseareconcludedtohaveanegligibleeffectontheannulusflowdistribution.PART8.8-E<ME<RGE<NCYOPE<RATINGPROCEDURE<S'<OPs'ALCULATIONSCRITERIAInputstotheEOPcalculationssuchasbulksteelresidualheatcapacityandreductionofreactorwaterinventoryshallbeaddressedbasedonrepairhardwaremassandwaterdisplacement.PART8.8.1-EME<RGENCYOPERATINGPROCE<DURES'OPs'ALCULATIONSCONFORMANCETheweightforeachrepairclampwasdetermined.FortheV4,V9andV10clamps,thetotalweightislessthan1000Ibswhichisnegligiblecomparedtothetotalshroudweight.Thedisplacedreactorwaterinventoryislessthantwocubicfeetwhichisalsonegligible.ThesearenegligibleeffectsontheEOPcalculations.9of14

PART8.9-RADIATIONE<F<FE<CTSONREPAIRDESIGNCRITE<RIATherepairdesignshallconsidertheeffectsofradiationonmaterialsandonradiationfluenceinducedrelaxationofpreloads.PART8.9.1-RADIATIONEFFECTSONREPAIRDESIGNCONFORMANCETheeffectsofradiationwereconsideredintheselectionoftherepairmaterialsand'abricationprocesses.AsdiscussedinPartA.2.1,allmaterialsusedintherepairhavebeenusedsuccessfullyforyearsintheBWRenvironment.Also,theeffectofrelaxationofthepinpreloadduetoradiationfluencewasconsideredinthepreloadselection.PART8.10-THERMALCYCLESCRITERIATherepairanalysesshallconsidertheplantthermalcyclesovertheremaininglifeasspecifiedinAppendixAofReference2.PART8.10.1-THE<RMALCYCLE<SCONFORMANCETherepairanalysesshowthatthefatigueusagesintheshroudandrepairhardwareareacceptableforthespecifiedplantthermalcycles.PART8.11-CHE<MISTRY/FLUXCRITERIATherepairdesignshallusematerialswhicharesuitableforusewiththeexistingandanticipatedreactorwaterchemistrycontrolmeasures.Anyeffectsofneutronfluxonmaterialsusedintherepairshallbeconsidered.PART8.11.1-CHE<MISTRY/FLUXCONFORMANCEThe300seriesandXM-19materialsselectedfortherepairaresuitableforusewiththeexistingandanticipatedreactorwaterchemistrycontrolmeasures.ThematerialsarenotsusceptibletogeneralcorrosionandareresistanttoIntergranularStressCorrosionCracking(IGSCC)inaBWRenvironment.Also,themaximumradiationfluenceswillhavenoeffectonrepairmaterialproperties.PART8.12-LOOSEPARTSCONSIDE<RATIONDURINGOPERATIONCRITERIAThedesignedrepairshallhavefeatureswhichensureallpartsaresecuredsoastopreventpartsfrombecominglooseandenteringthecoreorbeingcarriedintodownstreamsystems.PART8.12.1-LOOSEPARTSCONSIDERATIONDURINGOPE<RATION~CC'CMANC'hevariouspartsthatmakeuptherepairclampassembliesaresecuredandrestrainedbyappropriatelockingdevicessuchaslockingcupsandcrimping.Theselockingdevicedesignshavebeenusedsuccessfullyformanyyearsinreactorinternals.Loosepiecescannotoccurwithoutfailureofthelockingdevicesorrepairassemblycomponents.Suchlockingdevicesandthestressesinthepartswhichmakeuptherepairclampsarewellwithinallowablelimitsforallplantoperatingconditions.IfanyofthelockingcuppartsI10of14 1'I weretofail,anyofthepartswhichweresubsequentlyreleasedwouldhavetopassthroughtherecirculationpumpsandlowerreactorinternalstoreachthecore.Largepartswouldnotbeabletopassthroughtherecirculationpumps.Althoughnotspecificallyanalyzed,theconsequencesofthesmallerpartswouldbeconsistentwiththeconsequencesofotherpostulatedloosepieces.PART8.13-INSPECTIONACCE<SSCRITERIAThedesignshallconsiderthefollowinginspectionaccessrequirements:~Therepairhardwareshallnotadverselyimpacttheaccesstootherreactorinternals,reactorvesselorECCScomponents.~Therepairhardwareshallnotinterferewithrefuelingoperationsorotherin-vesselactivities.~Therepairshallberemovableasfrequentlyaseachoutagewithoutpermanentdamagetotherepaircomponentsand/orexistinginternals.~Allrepairpartsshallbereadilyremovableandreplaceable.~TherepairdesignshallpermitfutureinspectionoftherepairhardwarepertherequirementsofReference5.PART8.13.1-INSPECTIONACCESSCONFORMANCEThedesignoftherepairisinconformancewithallcriterialistedinPartB.13abovebasedonthefollowing:~Therepairclampshavealowprofileandfitsnuglyagainstthecor'eshroud.~TherepairclampscanberemovedinastraightforwardmannerbyreversingtheinstallationstepsdiscussedinPartA.1above.PART8.14-CREVICE<SCRITE<RIATherepairdesignshallbereviewedforcrevicesbetweenrepaircomponentsandbetweenrepaircomponentsandoriginalstructurestoassurethatcriteriaforcrevicesimmunetostresscorrosioncrackingaccelerationaresatisfied.PART8.14.1-CREVICESCONIORMANCETherepairdesignhasconsideredcrevicesandtheirimpactonstresscorrosioncrackingbyusingmaterialswhicharehighlyresistanttoIntergranularStressCorrosionCracking(IGSCC).Thematerial'sIGSCCresistanceisverifiedbytestingperrequirementsofASTMA262PracticeE.PART8.15-MATERIALSCRITE<RIAAllmaterialsshallbeinconformancewithBWRVIP-02(Reference1)requirements.11of14 0

PART8.15.1-MATERIALSCONFORMANCEAllmaterialsareusedinconformancewithBWRVIP-02(Reference1)requirements.Specifically,allrequirementsforstainlesssteelmaterialsasspecifiedinBWRVIP-02aremetfortherepairmaterialsasdiscussedinPartA.2above.PART8.16-MAINTE<NANCE/INSPECTIONOFREPAIRHARDWARE~CRITRRIAThedesignedrepairshallminimizefutureinspectionsandmaintenanceofrepaircomponentsandpermitfutureinspectionoftherepairhardware.PART8.16.1-MAINTENANCE/INSPECTIONOFREPAIRHARDWARECONFORMANCEInspectionoftherepairclampsinfuturerefuelingoutageswillbebasedontherequirementsinSection4.2ofBWRVIP-07[5],"BWRVesselInternalsProject,GuidelinesforReinspectionofCoreShrouds."Theinspectionwillinvolvethevisualinspectionoftheoverallclampsandthethreadedpin-to-eccentricandlockingscrew-to-eccentriccrimpareastoconfirmnochangefromtheirconditionduringthepost-installationinspectionPART8.17-IMPACTONTIE-RODHORIZONTALWELDRE<PAIR~CRITRRITheverticalweldrepairshallnotimpactthecoreshroudtie-rodrepairandthesupportingsafety,stressandseismicanalyses(References6,7and8).PART8.17.1-IMPACTONTIE-RODHORIZONTALWE<LDRE<PAIR~CONRORMANCRThesafety,stressandseismicanalysesforthecoreshroudtie-rodrepair(References6,7and8)werereviewedandevaluatedtodetermineifthereisanyimpactfromtheverticalweldrepair.Resultsofthereview/evaluationare:~NospecificdiscussionofrequirementsfortheshroudverticalweldswasfoundinReferences6,7and8.However,itisclearthatthedesignandtheanalysesofthetie-rodrepairarebasedontheshroudretainingacylindricalconfigurationintheeventofcrackingintheverticalwelds.Accordingly,theverticalweldrepairisrequiredtopreservethecylindricalshroudconfigurationforallappliedloadsandloadcombinations.AsidentifiedinPartB.2above,thisisoneofthefunctionalrequirementsfortheverticalweldrepair.~Noallowanceforcoolantleakagethroughcrackedverticalweldsisconsideredinthesafetyanalysisforthetie-rodrepair(Reference6).Therefore,theverticalweldrepairisrequiredtolimitverticalweldleakage,incombinationwithotherleakagesources,towithinacceptablelevelsforallplantconditions.ThisisafunctionalrequirementfortheverticalweldrepairasstatedinPartB.2above.12of14

~PerReference8,theseismicfuelloadsaretransmitteddirectlythroughthetopguideorcoresupportplateringstothetie-rodradialrestraints.Therefore,itisthestiffnessoftheseringsandnotthestiffnessoftheshroudcylindersthataffectsthefuelseismicresponse.~Forashroudcylinderwithfullycrackedverticalweldsandendconditionsthatprovidenolateralshearrestraint,thelateralstiffnesswouldbereduced.Sinceshroudstiffnessisaparameterintheshroudseismicmodel,thisreductioncouldimpacttheseismicanalysisresults.However,thispotentialimpactisnotsignificantsinceforalloftheseismiccasesconsideredinSection5ofReference8,theHl-H2andH4-H5shroudcylindershavehingedconnectionstotheadjacentcylinders.Thishingedconnectionprovidessheartransferbetweentheshroudcylindersandpermitstheshroudcylinderstoretaintheiruncrackedmomentofinertiaandrotationalstiffness.Basedontheabove,theverticalweldrepairhasnoimpactonthetie-rodrepairandthesupportingsafety,stressandseismicanalyses.PARTC-CONCLUSIONSThissafetyevaluationhasdeterminedthattheadditionofverticalweldrepairtotheNMP-1coreshrouddoesnotincreasetheprobabilityofoccurrenceorconsequencesofanaccidentpreviouslyevaluatedintheNMP-1UpdatedFinalSafetyAnalysisReport(UFSAR)(Ref.4),doesnotincreasetheprobabilityofoccurrenceorconsequencesofamalfunctionofequipmentimportanttosafetyevaluatedpreviouslyintheUFSAR,doesnotcreatethepossibilityofanaccidentormalfunctionofequipmentimportanttosafetyofadifferenttypeevaluatedpreviouslyintheUFSARorreducethemarginofsafetyasdefinedinthebasisforanytechnicalspecification.Therefore,itisconcludedthattheadditionofaverticalweldrepairdoesnotconstituteanunreviewedsafetyquestion.PARTD-REFERENCESl.EPRIReport,"BWRVIPVesselandInternalsProject,CoreShroudRepairDesignCriteria(BWRVIP-02),"Revision2,FifthDraftReport,April1988.2.MPRSpecificationNo.249014-001,"DesignSpecificationforNineMilePointNuclearStationUnit1(NMP1)CoreShroudVerticalWeldRepair,"Revision2,December28,1998.13.ASMEBoilerandPressureVesselCode,SectionIII,Division1-SubsectionNG,"CoreSupportStructures,"1989Edition.4.NineMilePointNuclearStationUnit1UpdatedFinalSafetyAnalysisReport,Revision15,November1997.5.EPRIReportTR-105747,"BWRVesselandInternalsProject,GuidelinesforReinspectionofBWRCoreShrouds(BWRVIP-07),"February1996.13of14

6.NineMilePointUnit1SafetyEvaluationNumber94-080,Rev.1forModificationN1-94-003,ReactorCoreShroudRepair.7.GENE-B13-01739-04,"NineMilePointUnit1ShroudRepairHardwareStressAnalysis(NMPCCalculationNo.SO-,Vessel-M028),"Revision0.8.GENE-B13-01739-03,"NineMilePointUnit1NuclearPowerStation,SeismicAnalysis,CoreShroudRepairModification(NMPCCalculationNo.SO-Vessel-M027),"Revision0.9.MPR-1966,"NineMilePointUnit1CoreShroudVerticalWeldRepairDesignReport,"December1998,Revision1.PARTE<-ATTACHME<NTS1.Figures1-1through1-5.14of14 0

6.0I31.25I2.018.501H1HHV5V1V3V6V2Y4'00V8SHROUDHEADFlANGETOPGUIDESUPPORT90.120000V9Y1100V10REPAIRCLAMP{nP)V1263.50.50H6222.13H6A4V13V15V1416COREPLATESUPPORTSHROUDSUPPORTRINGL~ma/144@)l+WlS1/61/66(~)FigureMNMP-1CoreShroud%'clds

ShroudLocidngScrew"V4VerticalWeldV4PlateCutoutlnShroudiWallLeftBayonetEccentricIIIIIRightBayonetEccentricThreadedPinl99SNPRASSOCIATESU.S.PATENTPENO9ICMMPR/NlOll0$IXIl0/N/NIMIFigure1-2.NineMilePoint-Unit1ExplodedViewofV4VerticalWeldClampAssembly

'h~t V4VerticalWeldLockingScrewShroudRightBayonetEccentricLeftBayonetEccentricThreadedPinlalMPRIlnonlyOl/1$/l41ALI)Figure0-3.NineMilePoint-UnitiInstalledV4VerticalWeldClampAssembly1998LIPRASSOOAIESU.S.PA1ENrPEtlDNG 0

VcChzShroudV9/V10'I/eNcalWeldIIjLockingScrew-CutoutinShroud'allV9/V10PlateLeftBayonetEccentricThreadedPinAightBayonetEccentricLLMPR/N%Ol~01ol/04/00I~Figure1R.NineMilePoint-Unit1ExplodedViewofV9/V10VerticalWeldClampAssemblyl998IIPRASSOCIATESU,S.PAIENrPENOINC

V4VerticalWeldShroudLockingScrewRightBayonetEccentricLeftBayonetEccentricV9/Vt0PlateThreadedPinQMPRtI<0OllOIot/ol/04IMtFigure1-5.NineMilePoint-Unit1InstalledV9/V10VerticalWeldClampAssemblyPC199SllPRASSOCIAIESU.S.PATOllPEIIDIIIG

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