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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ENCLOSUKE3 1%1NEMHEPOINTUI.'GTl(NMPl)CORESHROUDVERTICALWELDREPAIRDESIGNREPORTNON-PROPMKTARY VERSION9902i00204 990203'DR ADOCK05000220PPDR 4~4'J raqMpRASSOCIATES INC.ENGINEERSNineMilePointUnit1CoreShroudVerticalWeldRepairDesignReportMPR-1966(NP)Non-Proprietary VersionRevision0January1999Preparedby:H.illiamMurdyReviewedby:-aiB.%wanner Approvedby:WilliamR.SchmidtPrincipal Contributors H.WilliamMcCurdy,MPRAssociates CraigB.Swanner,MPRAssociates, BenjaminR.Lane,MPRAssociates QUALITYASSURANCE DOCUMENTThisdocumenthasbeenprepared,

reviewed, andapprovedinaccordance withtheQualityAssurance requirements of10CFR50AppendixB,asspecified intheMPRQualityAssurance Manual.320KINGSTREE'TALEXANDRIA, VA22314-3230 703.519-0200 FAX:703-519-0224

TableofContents1Introduction andSummary.~.~~....~.........

~......~..~..~1-11.1Introduction 1.2Summary............

~~.1.2.1RepairOverview.......................................

1-11.2.2Structural andDesignEvaluations,.......................

1-11.2.3SystemEvaluations

..........

1.2.4MaterialandFabrication 1-21-21.2.5Pre-Modification andPost-Modification Inspection

......2Background 2.1ReactorInternals DesignBases...........

~....~........

2.2Functional Requirements 1-22-12-13Description ofRepair.............

~...~~...........

~......~3-13.1DesignObjectives

.3.2DesignCriteria...........3-13-13.3Description ofRepairComponents andDesignFeatures....4Structural andDesignEvaluation

.~~...~~~..~~.....~....4.1DesignLoadsandLoadCombinations 4.2AnalysisModelsandMethods4.3RepairHardwareEvaluation

~4.3.1RepairHardwareStructural Evaluation 4.3.2FlowInducedVibration 4.3.3Radiation Effects.3-14-14-14-14-14-14-24.4ShroudEvaluation

......4-34.5ImpactonTie-RodRepair....

4-3MPR-1966(NP)Revision0n

4.6LoosePartsConsiderations

.444.7Installation Cleanliness

~445SystemsEvaluation

.......................................

5-15.1BypassFlowforNormalOperation

.5.2BypassFlowforOtherConditions

..~~~~~~~~~5-25.3Downcomer FlowandOtherEffects............

~..,........

5-26Materials andFabrication

................................

6-16.1MaterialSelection 6-16.2MaterialProcurement Specifications 6.3MaterialFabrication

~~~~~~~~~~~~~~6-27Pre-Modification andPost-Modification inspection 7.1Pre-Modification Inspection 7.2Post-Modification Inspection

~~~~~~~~~~~~~7-1~~~~~~~~717.2.1PriortoRPVReassembly

.7.2.2DuringSubsequent Refueling Outages~~~~~~~~~~~~~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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Installed V4VerticalWeldClamp~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ExplodedViewofV9/V10VerticalWeld~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Installed V9V/10VerticalWeldClamp~~~~~~~~~MPR-1966(NP)Revision0

introduction andSummary1.1Introduction Thisreportdocuments thedesignofthecoreshroudverticalweldrepairfortheNineMilePointNuclearStationUnit1(NMP-1).Thereportfollowstheguidelines inBWRVIP-04

[1],"GuideforFormatandContentofCoreShroudRepairSubmittals."

Asummaryoftherepairdesign,supporting evaluations,

material, fabrication andinspection requirements isprovidedinthisreport.1.2SummaryTheNMP-1coreshroudverticalweldrepairaddresses thecrackingofverticalweldsV4,V9andV10(seeFigure1-1).TherepairisnotincludedundertheASMEBoilerandPressureVesselCodeSectionXIdefinition forrepairorreplacement.

Rather,therepairisdeveloped asanalternative repairpursuantto10CFR50.55a(a)(3).

Assummarized below,therepairsatisfies therequirements specified inBWRVIP-02

[2],"CoreShroudRepairDesignCriteria."

Therepairisconsistent withthecurrentplantlicensing basisandensuresthattheshroudwillsatisfyitsoperational andsafetyfunctions.

1.2.1RepairOverviewAsshowninFigures1-2through1-5,therepairconsistsofrepairclampswhichholdtheshroudtogetheratthefailedverticalweldlocations.

Therepairdesignspecification isprovidedinReference 3.1.2.2Sfrucfural andDesignEvaluations Assummarized below,therepairsatisfies thestructural requirements specified inReferences 2,3and4.~Ridl-TPpIIpdIpIIIdcriteriafortherepairhardware.

Inparticular, althoughtherepairisnotconsidered anASMEB&PVCoderepair,therepairsatisfies theDesignbyAnalysisstressandfatiguecriteriaoftheASMEBoiler&MPR-1966(NP)Revision0

PressureVesselCode,SectionIII,Subsection NG[4].SeeSection4.3ofthisreportforadditional information ontherepairassemblystructural evaluation.

~Shroud-Thestressesintheshroudresulting fromtherepairarewithinthestressallowables ofSectionIII,Subsection NGoftheASMEBoiler&PressureVesselCode[4].SeeSection4.4ofthisreportforadditional information ontheshroudstructural evaluation.

1.2.3SystemEvaiuafions Theleakagethroughthefailedverticalweldswiththerepairclampsinstalled wascalculated andfoundtobewithintheacceptance criteria.

Thisincludedtheleakagethroughtherepairclampshroudattachments.

SeeSection5ofthisreportforadditional information ontheseevaluations.

1.2.4MaferiaiandFabrication Thematerials specified foruseintherepairassemblies areresistant tostresscorrosion crackingandhavebeenusedsuccessfully intheBWRreactorcoolantsystemenvironment.

Therepairassemblies arefabricated fromsolutionannealedType304or316stainless steelorsolutionannealedTypeXM-19stainless steel.Noweldingispermitted inthefabrication orinstallation oftherepair,andspecialcontrolsandprocessqualifications areimposedinthefabrication oftherepairtoassureacceptable materialsurfaceconditions aftermachining.

SeeSection6ofthisreportforadditional information onrepairhardwarematerials andfabrication.

1.2.5Pre-Modification andPost-Modification Inspections Theinspections tobeperformed tosupporttherepairaresummarized below.Pre-Modification Insection-Priortoinstallation oftheshroudrepair,visualinspections willbeperformed tosupporttherepairinstallation.

Theseinspections arelistedinSection7.1.PostModification Insection-Priortoreactorpressurevesselreassembly, visualinspections willbeperformed toverifytheproperinstallation ofrepair.Thescopeoftheseinspections isdiscussed inSection7.2.Inspection oftheshroudandtherepairinfuturerefueling outageswillbebasedontheBWRVIP-07

[6],"Guidelines forReinspection ofCoreShrouds."

MPR-1966(NP)Revision01-2

~I~~s~~+~0S~R~~~o~~~o~~~~~~~~~I

ShroudLockingScrew"t14VerticalWeldV4PlateCutoutlnShroudlWallLeftBayonetEccentric

'8RightBayonetEccentric ThreadedPln199SNPRASSOCIATES U.S.PATENTPENONG5BMPR)slOl~OS00)l0/l1/N(AD)Figure1-2.NineMilePoint-Unit1ExplodedViewofV4VerticalWeldClampAssembly

V4VerticalWeldLoctdngScrewShroudRightBayonetEccentric LeftBayonetEccentric V4PlateThreadedPinldMPR/tieOllOl0$/21/$4(JSI)Figure1-3.NineMilePoint-Unit1Installed V4VerticalWeldClampAssemblyI998IIPRASSOCAIES U.S.PAIEIITPEIIOIIIC

ShroudIV9jV10VerticalWeldLockingScrewCutoutinShroudWallV9/V10PlateLeftBayonetEccentric ThreadedPinRightBayonetEccentric FAHMPR/N$01~01ol/c4/ssIAu)Figure1%.NineMilePoint-Unit1ExplodedViewofV9/V10VerticalWeldClampAssemblyPCI99SMPRASSOCNTES U.S.PAIENrPENQNG

V4VerticalWeldShroudLockingScrewRightBayonetEccentric LeftBayonetEccentric V9jV10PlateThreadedPinQMPRtlnOl~C4IN/4I/nIAJTFigure0-5.NineMilePoint-UnitIInstalled V9/V10VerticalWeldClampAssemblyPC199SIJPRASSOCIATES IAS.PATEtITPEIITNNO

2Backround2.1Reactorinternals DesignBasesFromtheNMP-1FinalSafetyAnalysisReport(Updated)

[5],thereactorinternals aredesignedto:1.Providesupportforthefuel,steamseparators, dryers,etc.,duringnormaloperation andaccidentcondition.

2.Maintainrequiredconfigurations andclearances duringnormaloperation andaccidentconditions.

3.Circulate reactorcoolanttocoolthefuel.4.Provideadequateseparation ofsteamfromwater.2.2Functional Requirements fortheRepairThefunctional requirements fortherepairareidentified inBWRVIP-02

[2].Therequirements are:1.Structurally replacetheverticalweldsandmaintainthestressesoftheaffectedshroudcylinderwithinASMESectionIIIstressallowables forallloadcombinations andservicelevels.2.Limitcoolantleakagethroughthecrackedverticalweldstoacceptable levelsfornormaloperation andtransient plantconditions.

NotethattheNMP-1plantdoesnotrequireafloodable volumetobemaintained foraccidentconditions toprovidefoxadequatecorecooling.MPR-1966(NP)Revision02-1

DescritionofReair3.1DesignObjectives Thefunctionoftherepairistostructurally replacefailedV4,V9andV10(seeFigure1-1)coreshroudwelds.3.2.DesignCriteriaTherepairisdeveloped asanalternative repairpursuantto10CFR50.55a(a)(3).

Therepairisconsistent withandmeetsthecriteriadeveloped bytheBoilingWaterReactorVesselandInternals Project,asstatedinBWRVIP-02

[2].Thedesignspecification fortherepairisprovidedinReference 3.Therepairisdesignedtosatisfythestructural requirements ofSectionIII,Subsection NG,"CoreSupportStructures,"

oftheASMEBoiler&PressureVesselCode[4].3.3.Description ofRepairComponents andDesignFeaturesTherepairclampisillustrated inFigures1-2through1-5:~Figures1-2and1-3showexplodedandinstalled viewsoftherepairclampforverticalweldV4.~Figures1-4and1-5showexplodedandinstalled viewsoftherepairclampforverticalweldsV9andV10.Eachrepairclampconsistsofaclampplateandtwobayoneteccentric/threaded pinassemblies.

Theclampisinstalled inthrough-wall holesmachinedintheshroudbyEDMprocesses oneachsideoftherepairedverticalweld.Therepairweldclamptransmits theshroudhooppressureforcewhichwouldnormallybetransmitted throughtheshroudverticalweld.Thestructural loadpathisfromtheshroudthroughabayoneteccentric/threaded pintotheclampplateandthroughtheclampplateandotherbayoneteccentric/threaded pinassemblybacktotheshroud.MPR-1966(NP)Revision03-1

Theinstallation stepsfortherepairclampareasfollows:~Therepairclampisassembled with:Thepinsretracted withtheirflangesurfacesflushwiththeplateinnersurfaces.

Thebayoneteccentrics rotatedtothepositionwherethepinaxisisalignedwiththecenterofthe1.563inchradiusportionoftheshroudhole.FortheV4clamp,therightbayoneteccentric/threaded pinassemblyisinsertedintheclampplateaftertheclampplatehasbeenmovedinpositionbetweenthecoreshroudandthecorespraypipe.~Thepinsarethreadedinwarduntiltheirflangesextendbeyondtheshroudinsidesurfaces.

~Thebayoneteccentrics arerotatedtobringthepinshaftsintothe1.265inchradiusportionoftheshroudholeandintocontactwiththeshroudholesurfaces.

~Thebayoneteccentrics arefixedintopositionwiththelockingscrewswhichextendintomatingslotsintheeccentrics.

Thelockingscrewsarefixedinpositionbycrimpingattwolocations.

~Thepinsarethreadedoutwardtobringtheirflangesurfacesintocontactwiththeshroudinnersurfaceandtorquedtoprovideaspecified preload.Anallowable of50percentforrelaxation ofpreloadduetocombinedthermalandirradiation effectsisprovidedinthepreloaddetermination.

~Thepinsarelockedinpositionbycrimpingtotheeccentric attwolocations.

Notethattheclampinstallation providesthefollowing features:

Theleakagepathsthroughtheshroudholesareeffectively sealedbytheextendedsealringportionsoftheclampplatewhicharemachinedtoaradiusequaltotheshroudradiusandseatontheshroudsurface.Thepreloadbetweenthepinflanges,theclampplateandtheshroudpreventsrelativedisplacement betweentherepairclampandshroudduetoflowinducedvibration loading.PerReference 10,clamploadingduetoshroudvibration isnegligible.

MPR-1966(NP)Revision03-2

Therepairdesignhasconsidered crevicesandtheirimpactonstresscorrosion crackingbyusingmaterials whicharehighlyresistant toIntergranular StressCorrosion Cracking(IGSCC).Thematerial's IGSCCresistance isverifiedbytestingperrequirements ofASTMA262PracticeE.SeeSection6ofthisdesignsummaryreportforfurtherdiscussion onmaterials andfabrication.

MPR-1966(NP)Revision03-3

Structural andDesinEvaluation 4.1DesignLoadsandLoadCombinations Theloadsandloadcombinations arelistedintheDesignSpecification fortherepair[3].Theseloadsandloadcombinations aresummarized inTable4-1.Acombination ofhandcalculations andfiniteelementanalysesareusedtodefinethedesignloads.Thecoreshroudpressuredifferentials listedintheDesignSpecification areusedinthedesignoftherepair.Theonlydesignloadsofsignificance totherepairarethoseduetodifferential pressureacrosstheshroudandthoseduetodifferential thermalexpansion betweentheshroudandrepairclamp.4.2AnalysisModelsandMethodology Analysismodelsandmethodsusedtoevaluatetherepairhardwareandexistingstructures arediscussed below.Acombination ofhandcalculations andfiniteelementanalyseswereusedtoevaluatetherepairhardwareandexistingstructures.

Three-dimensional finiteelementanalysesusingtheANSYScodewereusedtodetermine thestructural responseoftheshroud.Handcalculations wereusedintheevaluations oftherepairhardware.

4.3RepairHardwareEvaluation 4.3.7RepairHardwareStructural Evaluation Therepairhardwaresatisfies thestructural criteria.

Inparticular:

~TheDesignbyAnalysisstressandfatiguecriteriaoftheASMEBoiler8r,PressureVesselCode,SectionIII,Subsection NGaresatisfied.

MPR-1966(NP)Revision04-1

~Themaximumfatigueusageintherepairassemblyduetothermalexpansion (including startupandshutdown) loadsoccurinthebayonetholeintherepairclampplate.Thefatigueusageatthislocationislessthan3%.~Themaximumfatigueusageintheshroudattherepairattachments isnegligible.

~Thefatigueusagefromflowinducedvibration isnegligible.

~ThereisnonetsectionyieldingforServiceLevelsA/8loads.Theratioofthecalculated stresstotheallowable stressforthelimitingloadcasesissummarized inTable4-2fortheclampcomponents.

4.3.2FlowInducedVibration Therepairclampswereanalyzedtoensurethatreactorcoolantflowwouldnotinduceunacceptable vibration.

Thefollowing basicapproachwasfollowedtoprovideresistance toflow-induced vibration loading:~Theflow-induced loadperunitareaoftherepairclampisconservatively calculated basedonadifference inpressureequaltoone-timestheflowvelocityheadacrosstheclampplate.~Theclampispreloaded bytightening thethreadedpinstoaforcewhichisgreaterthanthesumoftheflow-induced loadplusthepressureleadactingtoejecttheclampfromtheshroud.Theminimumpreloadisincreased byafactorof50%toaccountforrelaxation duetocombinedthermalandirradiation effects.Thisapproachprovidesassurance thatnoclampdisplacements andnoalternating stresswillresultfromtheflow-induced vibration loading.NotethatperTableB.6.1ofReference 10,theshroudvibration amplitude isonlyonemilandtherefore hasanegligible effectontherepairclampvibration.

4.3.3Radiation EffectsTheeffectsofradiation wereconsidered intheselection oftherepairmaterials andfabrication processes.

Relaxation duetothermalandirradiations effectswasconsidered inthedetermination ofthreadedpinpreload.Asdiscussed inSection6,allmaterials usedintherepairhavebeenusedsuccessfully foryearsintheBWRenvironment.

MPR-1966(NP)Revision04-2

4.4ShroudEvaluation Thestresses1nthecoreshroudwereevaluated tothestresscriteriaoftheASMEB&PVCode,SectionIII,Subsection NG[4].Theratioofcalculated shroudstressestotheallowable stressforthelimitingloadcasesissummarized inTable4-3.Asshowninthetable,theshroudcancarrytheappliedloadswithinthecodestressallowables foralldefinedloadings.

4.5ImpactonTie-RodRepairThesafety,stressandseismicanalysesforthecoreshroudtie-rodrepair(References 7,8and9)werereviewedandevaluated todetermine ifthereisanyimpactfromtheverticalweldrepair.Resultsofthereview/evaluation are:Nospecificdiscussion ofrequirements fortheshroudverticalweldswasfoundinReferences 7,8and9.However,itisclearthatthedesignandtheanalysesofthetie-rodrepairarebasedontheshroudretaining acylindrical configuration intheeventofcrackingintheverticalwelds.Accordingly, theverticalweldrepairisrequiredtopreservethecylindrical shroudconfiguration forallappliedloadsandloadcombinations.

Asidentified inSection2.2above,thisisoneofthefunctional requirements fortheverticalweldrepair.Noallowance forcoolantleakagethroughcrackedverticalweldsisconsidered inthesafetyanalysisforthetie-rodrepair(Reference 7).Therefore, theverticalweldrepairisrequiredtolimitverticalweldleakage,incombination withotherleakagesources,towithinacceptable levelsforallplantconditions.

Thisisafunctional requirement fortheverticalweldrepairasstatedinSection2.2above.PerReference 9,theseismicfuelloadsaretransmitted directlythroughthetopguideorcoresupportplateringstothetie-rodradialrestraints.

Therefore, itisthestiffness oftheseringsandnotthestiffness oftheshroudcylinders thataffectsthefuelseismicresponse.

Forashroudcylinderwithfullycrackedverticalweldsandendconditions thatprovidenolateralshearrestraint, thelateralstiffness wouldbereduced.Sinceshroudstiffness isaparameter intheshroudseismicmodel,thisreduction couldimpacttheseismicanalysisresults.However,thispotential impactisnotsignificant sinceforalloftheseismiccasesconsidered inSection5ofReference 9,theH1-H2andH4-H5shroudcylinders havehingedconnections totheadjacentcylinders.

Thishingedconnection MPR-1966(NP)Revision04-3

providessheartransferbetweentheshroudcylinders andpermitstheshroudcylinders toretaintheiruncracked momentofinertiaandrotational stiffness.

Forthetie-roddesignbasisconfiguration withaclearance of0.75inchbetweentheshroudandthemid-supports, Reference 9determines thattherearenolateralseismicloadsappliedtotheshroudduringaseismicevent.However,withtheas-installed clearance of0.375inchbetweentheshroudandthemid-supports, thereareseveralLevelDloadcombinations wheretherelativeseismicdisplacement atthemid-support exceedsthe0.375inchclearance.

Theresulting mid-support loadwasevaluated asaprimaryload,andtheloadsreactedbytheverticalweldrepairweredetermined tobeacceptable.

Basedontheabove,theverticalweldrepairhasnoimpactonthetie-rodrepairandthesupporting safety,stressandseismicanalyses.

4.6.LoosePartsConsideration Thevariouspiecesthatmakeuptherepairassemblies arecapturedandrestrained byappropriate lockingdevicessuchaslockingcupsandcrimping.

Theselockingdevicedesignshavebeenusedsuccessfully formanyyearsinreactorinternals.

Loosepiecescannotoccurwithoutfailureofthelockingdevicesorrepairassemblycomponents.

Suchlockingdevicesandthestressesinthepieceswhichmakeuptherepairclampsarewellwithinallowable limitsfornormalplantoperation.

4.7.Installation Cleanliness Alltoolingusedforinstallation willbeinventoried andsubjected toforeignmaterialexclusion procedures wheninthereactorvesselarea.Toolingwillbecheckedforloosepartspriortoinstallation intothecanal.Furthermore, thetoolingwillbeextensively fieldhardenedpriortositedeployment toreducethepossibility oftoolfailuresand/orbreakswhichcouldpotentially resultinloosepartsremaining inthevessel.Iffailuresoccur,thepartswillberetrieved fromthereactorvesselorcavity.Foreachrepairclamp,through-thickness holesaremachinedintheshroudsupportusingtheEDMprocess.Thisprocessresultsinaveryfinedebris(swarf'eing generated.

Thisdebrisisprimarily comprised ofcarbon,nickel,iron,chromium, etc.,whicharetheprimaryelementscontained intheshroudandEDMelectrode material.

Thisswarfisflushedandvacuumedfromthecutduringthemachining operation, thenfilteredpriortodischarge backintothecavity.TheEDMelectrode isdesignedtoonlygenerateswarf.Aslugisnotgenerated astheelectrode breaksthroughtheinsidesurfaceoftheshroud.Also,adebriscollection systemisMPR-1966(NP)Revision044

positioned ontheshroudinsidesurfacetocollecttheEDMswarfgenerated whentheEDMelectrode breaksthroughtheinsidesurfaceoftheshroud.TheEDMdebrissystemhasa10micronanda2micronfilterinseries.Eachfilterhas200sq.ft.ofeffective surfacearea.The10micronfilterisratedat99%efficient for10micronsand80%efficient forjustbelow2.5microns.The2micronfilteris99%efficient for2micronsand90to93%efficient for1micron.Asthesefiltersareloaded,theirefficiency willgreatlyincrease.

Thetotalamountofswarfcollected bythisEDMdebriscollection systemhasbeenqualified.

Thedebrissystemcollected over95%ofthedebristhatwasgenerated.

Thisqualification wasperformed withoutaninternaldebriscup.

Therefore, thetestwasconservative.

Thesmallamountofswarfnotcollected bytheEDMdebrissystemisnotdetrimental totheBWRsystem.'ISubsequent tocompletion oftherepairhardwareinstallation activities, afinalvideoinspection inthereactorvesselandcavitywillbeperformed toverifynoforeignobjectentryduringtherepair.MPR-1966(NP)Revision04-5

Table4-1CoreShroudVerticalWeldRepairDesignLoadsandLoadCombinations No.EventNormalOperation UpsetNo.1UpsetNo.2Emergency No.1Emergency No.2Emergency No.3FaultedNo.1FaultedNo.2FaultedNo.3LoadCombination<'1't'1'<'1 NormalPressure+DW+SteadyStateThermalUpsetPressure+DW+UpsetThermalUpsetPressure+DW+OBE+SteadyStateThermal"'ormal Pressure+DW+DBESteamLineLOCA+DWRecirculation OutletLineLOCA+DWSteamLineLOCA+DW+DBERecirculation InletLineLOCA+DW+DBERecirculation OutletLineLOCA+DW+DBENotes:(1)Loadcombinations asspecified inTable2-2ofGENE-B13-01739-04

[8].(2)DW=Deadweight, LOCA=LossofCoolantAccident, DBE=DesignBasisEarthquake, OBE=Operating BasisEarthquake.

(3)Alleventsincludeflowloads.(4)OBEloadsareequivalent toDBEloads.(5)Theonlydesignloadsfortherepairclampareexpectedtobethoseduetodifferential pressureacrosstheshroudandthoseduetodifferential thermalexpansion betweentheshroudandrepairclamp.Otherloadsshallbeevaluated toconfirmthattheyneednotbeconsidered asdesign-basis loads.MPR-1966(NP)Revision04-6

Table4-2LimitingStressesintheRepairClampAssemblyRepairLocationLimitingStressLocationServiceLevel:ServiceCondition StresstypeStressLimitStressRatioV9orV10BayonetConnection BayonetConnection BayonetConnection A:NormalOperation B:UpsetPressureB:LossofFeedwater ThermalTransient BearingBearingBearing1.0Sy0.4001.0Sy0.6041.0Sy0.636BayonetConnection C:SteamLineBreakBearing1.5Sy0.994PlateatBayonetHoleA:NormalOperation MembranePlusBending1.5Sm0.367PlateatBayonetHoleB:UpsetPressureMembranePlusBending1.5Sm0.555V4BayonetConnection B:LossofFeedwater ThermalTransient Bearing1.0Sy0.479PlateatBayonetHoleC:SteamLineBreakMembranePlusBending2.25Sm0.915MPR-1966(NP)Revision04-7

Table4-3ShroudStressRatioSummaryRepairLocationV9orV10V4ServiceLevel:ServiceCondition A:NormalOperation B:UpsetPressureB:LossofFeedwater Transient C:MainSteamLineBreakA:NormalOperation B:UpsetPressureB:LossofFeedwater Transient StressTypePrimaryMembranePrimaryMembranePlusBendingPrimaryPlusSecondary MembraneatHolePrimaryMembranePrimaryMembranePlusBendingPrimaryPlusSecondary MembraneatHolePrimaryPlusSecondary MembranePlusBendingPrimaryPlusSecondary MembraneatHolePrimaryMembranePrimaryMembranePlusBendingPrimaryMembranePrimaryMembranePlusBendingPrimaryPlusSecondary MembraneatHolePrimaryMembranePrimaryMembranePlusBendingPrimaryPlusSecondary MembraneatHolePrimaryPlusSecondary MembranePlusBendingPrimaryPlusSecondary MembraneatHoleStressLimitSm1.5Sm3SmSm1.5Sm3Sm3Sm3Sm1.5Sm2.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

5.2BypassFlowforOtherConditions Asdiscussed inPartB.3ofReference 7,therearenodetrimental effectsofshroudbypassfloweitheronplantanticipated abnormaltransients oronemergency corecoolingsystemperformance.

5.3Downcomer FlowandOtherEffectsThe'effects oftherepairclampassemblyontheflowinthereactorvesseldowncomer regionare:~TheV4repairclampreducestheflowareainthedowncomer atthetopofthecoreshroudbyapproximately 2.5percent.TheV9/VOclampswouldreducetheflowareabyalesseramountbecausetheyarepositioned atalowerelevation wherethedowncomer flowareaisgreater.~Thepressuredropassociated withtheV4clampisapproximately

0.0 06psidfornormaloperation

and0.044psidfortherecirculation linebreakcondition.

FortheV9/V10clamps,thepressuredropislessthanfortheV4clamp.FortheV4,V9andV10clamps,thetotalweightislessthan1000lbswhichisnegligible comparedtothetotalshroudweight.Thedisplaced reactorwaterinventory islessthantwocubicfeetofwater,whichisalsonegligible.

MPR-1966(NP)Revision05-2

Materials andFabrication 6.1MaterialSelection Thematerials specified foruseintherepairclampsareresistant tostresscorrosion crackingandhavebeenusedsuccessfully intheBWRreactorcoolantsystemenvironment.

AsshowninTable6-1,therepairclampsarefabricated fromsolutionannealedType304or316orTypeXM-19stainless steel.XM-19materialisusedforallpartsexceptthelockingscrewwhereType304/316orTypeXM-19stainless steelisused.AsrequiredbytheDesignSpecification, allmaterials specified foruseintheshroudrepairareinaccordance withASMEorASTMapprovedspecifications.

Allmaterials havebeenpreviously usedintheBWRenvironment similartothatexperienced bytherepairclamps.Thematerials arenotsusceptible togeneralcorrosion andareresistant toIntergranular StressCorrosion Cracking(IGSCC)inaBWRenvironment.

Additional information onmaterialspecification, procurement andfabrication requirements implemented toensurethattherepairhardwareishighlyresistant toIGSCCisprovidedinSections6.2and6.3.Materialproperties andallowable stressesforrepaircomponents areasspecified intheASMEB&PVCode,SectionsIIandIII,1989EditionforClass1components.

6.2MaterialProcurement Specifications Allhardwareisconstructed fromaustenitic stainless steelmaterial.

Weldingonthesematerials isprohibited bytheprocurement requirements.

Thesematerials asprocured, arehighlyresistant toIGSCC.NDEofmaterialusedforload-bearing membersisperformed inaccordance withASMECodeSectionIII,Subsection NG-2000.Specificmaterialrequirements aresummarized belowforthematerialusedintherepair.Allstainless steelmaterialisprocuredinaccordance withtheapplicable ASMEorASTMstandards supplemented bythefollowing:

~Type304/316alloyshave0.03%maximumcarbon.TypeXM-19alloyhas0.04%maximumcarbon.Allstainless steelmaterials arefullcarbidesolutionannealedandeitherwaterorforcedairquenchedfromthesolutionannealing MPR-1966(NP)Revision06-1

temperature sufficient tosuppresschromiumcarbideprecipitation tothegrainboundaries inthecenterofthematerialcrosssection.Solutionannealing ofthematerialisthefinalprocessstepinmaterialmanufacture.

ASTMA262PracticeEtestsareperformed oneachheat/lotofstainless steelmaterialtoverifyresistance tointergranular attackandthatanon-sensitized microstructure exists(nograinboundarycarbidedecoration).

Pickling, passivation oracidcleaningofloadbearingmembersisprohibited aftersolutionannealing unlessanadditional

0.0 10inchesmaterialthickness

isremovedbymechanical methods.Forothernon-loadbearingitems,metallography at500Xisperformed onmaterials fromeachheat,similarly processed, toverifyexcessive intergranular attackhasnotoccurred.

Controlsarealsospecified intheprocurement documents toprecludematerialcontamination duringmaterialprocessing andhandlingfromlowmeltingpointmetals,theiralloysandcompounds, aswellassulfurandhalogens.

6.3MaterialFabrication Noweldingorthermalcuttingisusedinthefabrication andassemblyoftheitems.Cuttingfluidsandlubricants areapprovedpriortouse.Controlsarealsospecified toprecludematerialcontamination duringprocessing andhandlingfromlowmeltingpointmetals,theiralloysandcompounds, aswellassulfurandhalogens.

Passivation, picklingoracidcleaningoftheitemsisprohibited.

Liquidpenetrant testingafterfinalmachining orgrindingoncriticalsurfacesisperformed.

Abusivemachining andgrindingpractices areavoided.Machining andgrindingprocessparameters andoperations arecontrolled.

Additionally, machining processparameters incriticalloadbearingthreadedareasarecontrolled, basedonqualification samples,whichhavebeensubjected tomacroscopic andmetallographic examinations andmicrohardness testing.Evaluations includehardnessmagnitudes anddepths,depthofseveremetaldistortion, depthofvisibleevidenceofslipplanesanddepthofcoldwork.MPR-1966(NP)Revision06-2 t

Table6-1RepairClampMaterials Parti'PlateBaonetEccentric ThreadedPinV4ClamXM-19XM-19XM-19Material'"

V9/V10ClamXM-19XM-19XM-19LockingScrewType304/316orXM-19@Type304/316orXM-19"'otes:(1)SeeFigures1-2and1Aforidentification ofparts.(2)Allmaterialissolutionannealed.

(3)XM-19materialisusedforthelockingscrewsfortheNMP-1repairclamps.MPR-1966(NP)Revision06-3

Pre-Modification andPost-Modification Insection7.1Pre-Modification Inspection Thefollowing visualinspections willbeperformed tosupporttherepairinstallation:

Theazimuthal locations oftheV4,V9andV10verticalweldswillbeidentified usingvisual,ultrasonic oreddycurrentmethods.Ifweldscannotbeidentified

visually, amethodforvisuallyidentifying theweldlocations willbedeveloped whichinvolvesmarkingtheshroudorindexingtotheweldfromotherinternals.

Following identification oftheV4weld,measurements willbemadetoverifythatadequateclearance existsbetweentheverticalweldandthecoresprayverticalpipingtoallowinstallation oftherepairclamp.TVvisualinspection willbeperformed attheV4,V9and/orV10verticalweldswheretheverticalrepairclampswillbeinstalled toassurethattherearenointerferences oradditional cracking.

Anengineering evaluation willbeperformed toaddressanyinterferences oradditional crackingidentified.

7.2Post-Modification Inspection 7.2.1PriortoRPVReassembly Properinstallation ofeachverticalweldrepairclampassemblywillbeconfirmed andrecordedbyTVvisualinspection fromboththeinsideandoutsideoftheshroud.Theinspection willverif'ythatallpartsareinstalled asrequiredandnoforeignobjectsremain.Asaminimum,thefollowing areaswillbeinspected:

Thetopandbottomoftherepairclamptoverifythattheclearance betweentheplateandtheshroudsurfaceisconsistent withthedesignclearance.

Theslotsintheplateandtheeccentrics toverif'ythattheeccentrics areproperlyalignedwiththeplate.Thetopofthelockingscrewtoverifythatthelockingscrewisfullyengagedwiththeeccentric.

MPR-1966(NP)Revision07-1

~Thepinliptoverifythatthepinlipareaoverlapping theshroudinsidesurfaceisconsistent withthedesignconfiguration.

~Theaxiallocationofthethreadedpinrelativetotheeccentric toqualitatively verifythatthethreadedpinisengagedwiththeshroudinnerdiameter.

~Thelockingscrewsandthreadedpinstoconfirmcrimping.

~Afinalvideoinspection inthereactorvesselandcavitywillbeperformed toverifynoforeignobjectentryduringtherepair.7.2.2DuringSubsequent Refueling OutagesInspection oftherepairclampsinfuturerefueling outageswillbebasedontherequirements inSection4.2ofBWRVIP-07

[6],"Guidelines forReinspection ofCoreShrouds."

Theinspection willinvolvethevisualinspection oftheoverallclampandthethreadedpin-to-eccentric andlockingscrew-to-eccentric crimpareastoconfirmnochangefromtheircondition duringthepost-installation inspection.

Inspection frequency willbeinaccordance withBWRVIP-07 requirements.

MPR-1966(NP)Revision07-2 0

References 1.EPRIReportTR-105692, "BWRVIPVesselandInternals Project,GuideforFormatandContentofCoreShroudRepairDesignSubmittals (BWRVIP-04),"

October1995.2.EPRIReport,"BWRVIPVesselandInternals Project,CoreShroudRepairDesignCriteria(BWRVIP-02),"

Revision2,FifthDraftReport,April1988.3.MPRSpecification No.249014-001, "DesignSpecification forNineMilePointNuclearStationUnit1(NMP1)CoreShroudVerticalWeldRepair,"Revision1,October12,1998.4.ASMEBoilerandPressureVesselCode,SectionIII,Division1-Subsection NG,"CoreSupportStructures,"

1989Edition.5.NineMilePointNuclearStationUnit1FinalSafetyAnalysisReport(Updated),

Revision15,November1997.6.EPRIReportTR-105747, "BWRVesselandInternals Project,Guidelines forReinspection ofBWRCoreShrouds(BWRVIP-07),"

February1996.7.NineMilePointUnit1SafetyEvaluation Number94-080,Rev.1forModification N1-94-003, ReactorCoreShroudRepair.8.GENE-B13-01739-04, "NineMilePointUnit1ShroudRepairHardwareStressAnalysis(NMPCCalculation No.SO-Vessel-M028),"

Revision0.9.GENE-B13-01739-03, "NineMilePointUnit1NuclearPowerStation,SeismicAnalysis, CoreShroudRepairModification (NMPCCalculation No.SO-Vessel-M027),"

Revision0.10.NEDE-13109, "OysterCreekStartupTestResults,"

July1970.MPR-1966(NP)Revision08-1

ENCLOSURE4 YOFNIAGARAMOHAWK10CFR50.59 SAFETYEVALUTION

CORESHROUDVERTICALWELDREPAIRCLAMPSSAFETYEVALUATION SUMMARYDI<'.SCRIPTION tTheNMP-1coreshroudverticalweldrepairaddresses thecrackingofverticalweldsV4,V9andV10(seeFigure1-1).Therepairbasically consistsofaclampwithaplatewithattachedpinswhichareinsertedintoholeswhicharemachinedbytheElectricDischarge Machining (EDM)processoneithersideoftheflawedverticalweld.Theclampsbridgeacrosstheflawedverticalweldandtransmitthepressureloadnormallytransmitted throughtheverticalweld.TwoclampsareusedfortheV9weld,twoclampsfortheV10w'eldandoneclampisusedfortheshorterV4weld.Therepairclampscanbeinstalled oneachweldindependently, thatisanyone,twoorthreeweldscanberepairedwiththeserepairclamps.Priortothisrepairbeingutilizedasastructural replacement forthewelds,anNRCapprovalwillberequired.

Assummarized below,therepairsatisfies therequirements specified inBWRVIP-02

[1],"CoreShroudRepairDesignCriteria."

Therepairisconsistent withthecurrentplantlicensing basisandensuresthattheshroudwillsatisfyitsoperational andsafetyfunctions.

Fordetailsoftherepairclampevaluations, whicharesummarized below,seethedesignreportfortherepair,reference 9.PARTA.1-GE<NERAL Therepairclampdesignisillustrated iriFigures1-2through1-5:~Figures1-2and1-3showexplodedandinstalled viewsoftherepairclampforverticalweldV4.~Figures1-4and1-,5showexplodedandinstalled viewsoftherepairclampsforverticalweldsV9andV10.Eachrepairclampconsistsofaclampplateandtwobayoneteccentric/threaded pinassemblies.

Theclampsareinstalled inthrough-wall holesmachinedintheshroudbyEDMprocesses oneachsideoftherepairedverticalweld.Therepairweldclampstransmittheshroudhooppressureforcewhichwouldnormallybetransmitted throughtheshroudverticalweld.Thestructural loadpathisfromtheshroudthroughabayoneteccentric/threaded pintotheclampplateandthroughtheclampplateandotherbayoneteccentric/threaded pinassemblybacktotheshroud.Theinstallation stepsfortherepairclampsareasfollows:~Therepairclampsareassembled with:Thepinsretracted withtheirflangesurfacesflushwiththeplateinnersurfacesThebayoneteccentrics rotatedtothepositionwherethepinaxisisalignedwiththecenterofthelargerportionoftheshroudhole.FortheV4clamp,therightbayoneteccentric/threaded pinassemblyisinsertedintheclampplateaftertheclampplatehasbeenmovedinposition.

~Thepinsarethreadedinwarduntiltheirflangesextendbeyondtheshroudinsidesurfaces.

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~Thebayoneteccentrics arerotatedtobringthepinshaftsintothesmallerradiusportionoftheshroudholeandintocontactwiththeshroudholesurfaces.

I~Thebayoneteccentrics arefixedintopositionwiththelockingscrewswhichextendintomatingslotsintheeccentrics.

Thelockingscrewsarefixedinpositionbycrimpingattwolocations.

~Thepinsarethreadedoutwardtobringtheirflangesurfacesintocontactwiththeshroudinnersurfaceandtorquedtoprovideaspecified preload.~Thepinsarelockedinpositionbycrimpingtotheeccentric attwolocations.

Notethattheclampinstallation providesthefollowing features:

~Theleakagepathsthroughtheshroudholesareeffectively sealedbytheextendedsealringportionsoftheclampplate,whicharemachinedtoaradiusequaltotheshroudradiusandseatontheshroudsurface.~Thepreloadbetweenthepinflanges,theclampplateandtheshroudpreventsrelativedisplacement betweentherepairclampandshroudduetoflowinducedvibration loading.PARTA.2-MATERIALS PARTA.2.1-MATERIALSELECTION Thematerials specified foruseintherepairclampsareresistant tostresscorrosion crackingandhavebeenusedsuccessfully intheBWRreactorcoolantsystemenvironment.

Therepairclampsarefabricated fromsolutionannealedTypeXM-19stainless steel~AsrequiredbytheDesignSpecification

[2],allmaterials specified foruseintheshroudrepairareinaccordance withASMEorASTMapprovedspecifications.

Allmaterials havebeenpreviously usedintheBWRenvironment similartothatexperienced bytherepairclamps.Thematerials arenotsusceptible togeneralcorrosion andareresistant toIntergranular StressCorrosion'Cracking (IGSCC)inaBWRenvironment.

Additional information onmaterialspecification, procurement andfabrication requirements implemented toensurethattherepairhardwareishighlyresistant toIGSCCisprovidedinA.2.2andA.2.3below.Materialproperties andallowable stressesforrepaircomponents areasspecified intheASMEB&PVCode,SectionsIIandIII,1989EditionforClass1components, MPR-1966[9].PARTA.2.2-MATERIALPROCUREMENT SPECII'ICATIONS Allhardwareisconstructed fromaustenitic stainless steelmaterial.

Weldingonthesematerials isprohibited bytheprocurement requirements.

Thesematerials asprocured, arehighlyresistant toIGSCC.NDEofmaterialusedforload-bearing membersisperformed inaccordance withASMECodeSectionIII,Subsection NG-2000.Specificmaterialrequirements aresummarized belowforthematerialusedintherepair.Allstainless steelmaterialisprocuredinaccordance withtheapplicable ASMEorASTMstandards supplemented bythefollowing:

~Type304/316alloyshave0.03%maximumcarbon.TypeXM-19alloyhas0.04%maximumcarbon.Allstainless steelmaterials arefullcarbidesolutionannealedandeitherwaterorforcedairquenchedfromthesolutionannealing temperature sufficient tosuppresschromiumcarbideprecipitation tothegrainboundaries inthecenterofthematerialcrosssection.2of14 0

~Solutionannealing ofthematerialisthefinalprocessstepinmaterialmanufacture.

ASTMA262PracticeEtestsareperformed oneachheat/lotofstainless steelmaterialtoverifyresistance tointergranular attackandthatanon-sensitized microstructure exists(nograinboundarycarbidedecoration).

~Pickling, passivation oracidcleaningofload-bearing membersisprohibited aftersolutionannealing unlessanadditional

0.0 10inchesmaterialthickness

isremovedbymechanical methods.Forothernon-loadbearingitems,metallography at500Xisperformed onmaterials fromeachheat,similarly processed, toverifyexcessive intergranular attackhasnotoccurred.

~Controlsarealsospecified intheprocurement documents toprecludematerialcontamination duringmaterialprocessing andhandlingfromlowmeltingpointmetals,theiralloysandcompounds, aswellassulfurandhalogens.

PARTA.2.3-MATERIALFABRICATION Noweldingorthermalcuttingisusedinthefabrication andassemblyoftheitems.Cuttingfluidsandlubricants areapprovedpriortouse.Controlsarealsospecified toprecludematerialcontamination duringprocessing andhandlingfromlowmeltingpointmetals,theiralloysandcompounds, aswellassulfurandhalogens.

Passivation, picklingoracidcleaningoftheitemsisprohibited.

Liquidpenetrant testingafterfinalmachining orgrindingoncriticalsurfacesisperformed.

Abusivemachining andgrindingpractices areavoided.Machining andgrindingprocessparameters andoperations arecontrolled.

Additionally, machining processparameters incriticalloadbearingthreadedareasarecontrolled, basedonqualification samples,whichhavebeensubjected tomacroscopic andmetallographic examinations andmicrohardness testing.Evaluations includehardnessmagnitudes anddepths,depthofseveremetaldistortion, depthofvisibleevidenceofslipplanesanddepthofcoldwork.Themachining practices usedinthefabrication processfortheclampswillbequalified toensurethecoldworklayeratthesurfacehasbeenmaintained toreducethepotential forIGSCCinitiation sites.PART8-ANALYSISPART8.1-REPAIRDESIGNLIFECRITERIAThedesignlifeoftherepairshallbefor25calendaryears(remaining lifeoftheplantincluding lifeextension) toinclude20effective fullpoweryears.PART8.1.1-REPAIRDESIGNLIFECONFORMANCE Allrepairhardwarehasbeendesignedfor25calendaryearstoinclude20effective fullpoweryears.Thisincludes:

~Selection of.stainless steelrepairmaterials whichhavebeensuccessfully usedinaboiling,waterreactorenvironment andwhichareresistant toIGSCC.~Consideration ofplanttransients representative of20effective fullpoweryearsofoperation (i.e.,120 thermaltransients fromstartupsandshutdowns and30scramswithlossoffeedwater pumps.)~Consideration ofradiation fluenceinducedrelaxation ofrepairhardwarepreload.3of14

PART8.2-FUNCTIONAL REUIREMENTS CRITERIAThefunctional requirements fortherepairareidentified inBWRVIP-02

[1].Therequirements are:1.Structurally replacetheverticalweldsandmaintainthestressesoftheaffectedshroudcylinders withinASMESectionIIIstressallowables forallloadcombinations andservicelevels.2.Limitcoolantleakagethroughthecrackedverticalweldstoacceptable levelsfornormaloperation andtransient plantconditions.

NotethattheNMP-1plantdoesnotrequireafloodable volumetobemaintained foraccidentconditions toprovideforadequatecorecooling.PART8.2.1-FUNCTIONAL REUIREMENTS CONFORMANCE Therepairhardwaresatisfies thestructural criteriafortherepairhardware.

Inparticular:

~TheDesignbyAnalysisstressandfatiguecriteriaoftheASMEBoiler8r,PressureVesselCode,SectionIII,Subsection NGaresatisfied fortheshroudandfortherepairclamps.Acomparison ofthecalculated andallowable stressintensities fortherepairclampsisshowninthefollowing table:4of14

LimitingStressesintheRepairClampAssemblyRepairLocationLimitingStressLocationBayonetConnection BayonetConnection ServiceLevel:ServiceCondition A:NormalOperation B:UpsetPressureStresstypeBearingBearingStressLimit1.0Sy1.0SyStressRatio0.4000.604BayonetConnection B:LossofFeedwaterThermalTransient Bearing1.0Sy0.636V9orV10BayonetConnection C:SteamLineBreakBearing1.5Sy0.994PlateatBayonetHolePlateatBayonetHoleBayonetConnection A:NormalOperation B:UpsetPressureB:LossofFeedwater ThermalTransient MembranePlusBendingMembranePlusBendingBearing1.5Sm1.5Sm1.0Sy0.3670.5550.479V4PlateatBayonetHoleC:SteamLineBreakMembranePlusBending2.25Sm0.915~Themaximumfatigueusageintherepairassemblyduetothermalexpansion (including startupandshutdown) loadsoccurinthethreadedpins.Thefatigueusageatthislocationislessthan3%.~Themaximumfatigueusageintheshroudattherepairattachments isnegligible.

~Thefatigueusagefromflowinducedvibration isnegligible.

Coolantleakagecriteriaandconformance arediscussed inPartsB.3,B.3.1,B.3.1.1andB.3.1.2below.PARTB.3-FLOWPARTITION CRITERIASof14

TherepairsshallconsiderleakagethroughtherepairedverticalweldsV4,V9andV10aswellasthroughtheattachment holesinthecoreshroud.Theleakageshallbelessthanallowables whicharedetermined basedonconsideration ofleakagefromothersources(crackedhorizontal welds,tie-rodlowerconnection, etc.).PART8.3.1-FLOWPARTITION CONI'ORMANCE Therepairdesignlimitsshroudleakagetotheallowables definedinReference 2forallplantoperating conditions.

Specifically, theleakageiswithinlimitsestablished forcorebypassleakageandsteamcarry-under asdiscussed inPartB.3.1.1below.Asdiscussed inPartB.3.1.2,theeffectsofleakageoncoremonitoring, anticipated abnormaltransients, emergency corecoolantandfuelcyclelengtharenegligible.

PART8.3.1.1-LEAKAGEFLOWEVALUATION AsstatedinPartB.2(Functional Requirements (Criteria))

ofthisreport,therepairisrequiredtolimitleakageofreactorcoolantthroughtherepairedverticalweldsduringnormalplantoperation.

Thisincludestheleakagethroughtheverticalweldsandtheleakagethroughtheholesmachinedthroughtheshroudwallfortherepairclampinstallation.

Considering leakagefromallothersources,allowable leakagerateswereestablished forthevertical'weld repairasdescribed inSection6.2oftheDesignSpecification

[2].Theselimitsare:~ThecombinedleakageratethroughweldsV9andV10andtheirrepairclampsshallbelessthan0.25%ofthetotalcoreflow(2%ofthecorebypassflow)fornormaldifferential pressure.

~ThecombinedleakagerateofsteamthroughweldV4anditsrepairclampshallbelessthan0.08%oftherecirculation (coreminussteam)flowfornormaldifferential pressure.

Thecalculated leakageflowratesthroughrepairedverticalweldsV4,V9andV10aresummarized asfollows:RepairedVerticalWeldLeakageLeakageFlowRate(gpm)RepairedWeldsCalculated Allowable V41.6396V9andV10247337PART8.3.1.2-COREMONITORING ANTICIPATED ABNORMALTRANSIENTS EMERGENCY CORECOOLINGSYSTEMANDFUELCYCLELENGTHAsdiscussed inPartsB.3.1.3throughB.3.1.6ofReference 6,theeffectofshroudleakageoncoremonitoring, anticipated abnormaltransients, emergency corecoolingandfuelcyclelengthareconsidered tonotbesignificant.

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PART8.3.1.3-CONCLUSION Theimpactoftheleakagethroughtherepairedshroudverticalweldsonplantoperation hasbeenevaluated asdiscussed aboveandfoundtobeacceptable.,

PART8.4-FLOW-INDUCED VIBRATION CRITERIAEvaluations shallbeperformed ofrepairclampvibration andwearforflow-induced vibration.

Thealternating stressfromtherepairclampvibration shallbelimitedtothematerialendurance stressortheASMECodeallowable stressforthenumberofvibration cycles.PART8.4.1-FLOW-INDUCED VIBRATION CONFORMANCE Therepairclampswereanalyzedtoensurethatreactorcoolantflowwouldnotinduceunacceptable vibration.

Thefollowing basicapproachwas'followed toprovideresistance toflow-inducedvibration loading:~Theflow-induced loadperunitareaoftherepairclampisconservatively calculated basedonadifference inpressureequaltoone-times theflowvelocityheadacrosstheclampplate.~Theclampispreloaded bytightening thethreadedpinstoaforcewhichisgreaterthanthesumoftheflow-induced loadplusthepressureloadactingtoejecttheclampfromtheshroud.Thisapproachprovidesassurance thatnoclampdisplacements andnoalternating stresswillresultfromtheflow-induced vibration loadingfornormalplantconditions.

PART8.5-LOADINGONEXISTINGINTE<RNAL COMPONENTS CRITERIATheloadingandresulting stressesfortheshroudshallbeevaluated andshowntobewithinallowables, asspecified inReferences 1,2and3.PART8.5.1-LOADINGONE<XISTING INTE<RNAL COMPONENTS

~CONFORM*NCR Thestressesinthecoreshroudwereevaluated tothestresscriteriaoftheASMEBEcPVCode,SectionIII,Subsection NG[3].Theshroudcancarrytheappliedloadswithinthecodestressallowables forallloadcasesasshowninthefollowing table.l7of14 0

ShroudStressRatioSummaryRepairLocationServiceLevel:ServiceCondition StressTypeStressLimitStressRatioA:NormalOperation PrimaryMembranePrimaryMembranePlusBendingSm0.201.5Sm0.19IPrimaryPlusSecondary MembraneatHole3Sm0.41B:UpsetPressurePrimaryMembranePrimaryMembranePlusBendingPrimaryPlusSecondary MembraneatHoleSm0.303Sm0.541.5Sm0.29V9orV10B:LossofFeedwater Transient C:MainSteamLineBreakPrimaryPlusSecondary MembranePlusBendingPrimaryPlusSecondary MembraneatHolePrimaryMembranePrimaryMembranePlusBending3Sm0663Sm0.551.5Sm0.472.25Sm0.46A:NormalOperation PrimaryMembraneSm0.07PrimaryMembranePlusBending1.5Sm0.08PrimaryPlusSecondary MembraneatHole3Sm0.31B:UpsetPressurePrimaryMembraneSm0.11PrimaryMembranePlusBendingPrimaryPlusSecondary MembraneatHole1.5Sm0.113Sm0.41B:LossofFeedwater Transient PrimaryPlusSecondary MembranePlusBendingPrimaryPlusSecondary MembraneatHole3Sm3Sm0.570.49V4C:MainSteamLineBreakIPrimaryMembranePrimaryMembranePlusBending1.5Sm0.172.25Sm0.188of14 0

PART8.6-SEISMICANALYSISCRITE<RIA Theexistingseismicevaluations ofthecoreshroudandhorizontal weldrepairhardwareshallbereviewedtodetermine iftheverticalweldrepairhardwareneedstoaddressanyseismicloadsordisplacements.

Stressesforanyverticalweldrepairseismicloadingshallbecalculated andcomparedwithallowables asspecified inReferences 1,2and3.PART8.6.1-SEISMICANALYSISCONFORMANCE Existingseismicevaluations werereviewedandseveralloadingcasesidentified whereaseismicloadwasappliedtotheH4-H5shroudcylinderbythemid-support ofthecoreshroudrepair.Theresulting loadsandstressesontheverticalweldrepairclampswereevaluated andfoundtobeacceptable.

PART8.7-ANNULUSFLOWDISTRIBUTION CRITERIAAnalysesshallbeperformed toshowthattherepairdesigndoesnotadversely affectthein-vessel flowcharacteristics inthedowncomer annulusregion.PART8.7.1-ANNULUSFLOWDISTRIBUTION CONFORMANCE Theevaluation oftheeffectsoftherepairclampassemblyontheflowinthereactorvesseldowncomer regiondetermined that:~TheV4repairclampreducestheflowareainthedowncomer atthetopofthecoreshroudbyapproximately 2.5percent.TheV9/V10clampswouldreducetheflowareabyalesseramountbecausetheyarepositioned atalowerelevation wherethedowncomer flowareaisgreater.~Thepressuredropassociated withtheV4clampisapproximately

0.0 06psidfornormaloperation

and0.044psidfortherecirculation linebreakcondition.

FortheV9/V10clamps,thepressuredropislessthanfortheV4clamp.Theflowarearestriction andpressuredropincreaseareconcluded tohaveanegligible effectontheannulusflowdistribution.

PART8.8-E<ME<RGE<NCY OPE<RATING PROCEDURE<S'<OPs'ALCULATIONS CRITERIAInputstotheEOPcalculations suchasbulksteelresidualheatcapacityandreduction ofreactorwaterinventory shallbeaddressed basedonrepairhardwaremassandwaterdisplacement.

PART8.8.1-EME<RGENCY OPERATING PROCE<DURES' OPs'ALCULATIONS CONFORMANCE Theweightforeachrepairclampwasdetermined.

FortheV4,V9andV10clamps,thetotalweightislessthan1000Ibswhichisnegligible comparedtothetotalshroudweight.Thedisplaced reactorwaterinventory islessthantwocubicfeetwhichisalsonegligible.

Thesearenegligible effectsontheEOPcalculations.

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PART8.9-RADIATION E<F<FE<CTS ONREPAIRDESIGNCRITE<RIA Therepairdesignshallconsidertheeffectsofradiation onmaterials andonradiation fluenceinducedrelaxation ofpreloads.

PART8.9.1-RADIATION EFFECTSONREPAIRDESIGNCONFORMANCE Theeffectsofradiation wereconsidered intheselection oftherepairmaterials and'abrication processes.

Asdiscussed inPartA.2.1,allmaterials usedintherepairhavebeenusedsuccessfully foryearsintheBWRenvironment.

Also,theeffectofrelaxation ofthepinpreloadduetoradiation fluencewasconsidered inthepreloadselection.

PART8.10-THERMALCYCLESCRITERIATherepairanalysesshallconsidertheplantthermalcyclesovertheremaining lifeasspecified inAppendixAofReference 2.PART8.10.1-THE<RMALCYCLE<SCONFORMANCE Therepairanalysesshowthatthefatigueusagesintheshroudandrepairhardwareareacceptable forthespecified plantthermalcycles.PART8.11-CHE<MISTRY/FLUX CRITERIATherepairdesignshallusematerials whicharesuitableforusewiththeexistingandanticipated reactorwaterchemistry controlmeasures.

Anyeffectsofneutronfluxonmaterials usedintherepairshallbeconsidered.

PART8.11.1-CHE<MISTRY/FLUX CONFORMANCE The300seriesandXM-19materials selectedfortherepairaresuitableforusewiththeexistingandanticipated reactorwaterchemistry controlmeasures.

Thematerials arenotsusceptible togeneralcorrosion andareresistant toIntergranular StressCorrosion Cracking(IGSCC)inaBWRenvironment.

Also,themaximumradiation fluenceswillhavenoeffectonrepairmaterialproperties.

PART8.12-LOOSEPARTSCONSIDE<RATION DURINGOPERATION CRITERIAThedesignedrepairshallhavefeatureswhichensureallpartsaresecuredsoastopreventpartsfrombecominglooseandenteringthecoreorbeingcarriedintodownstream systems.PART8.12.1-LOOSEPARTSCONSIDERATION DURINGOPE<RATION

~CC'CMANC'hevariouspartsthatmakeuptherepairclampassemblies aresecuredandrestrained byappropriate lockingdevicessuchaslockingcupsandcrimping.

Theselockingdevicedesignshavebeenusedsuccessfully formanyyearsinreactorinternals.

Loosepiecescannotoccurwithoutfailureofthelockingdevicesorrepairassemblycomponents.

Suchlockingdevicesandthestressesinthepartswhichmakeuptherepairclampsarewellwithinallowable limitsforallplantoperating conditions.

IfanyofthelockingcuppartsI10of14 1'I weretofail,anyofthepartswhichweresubsequently releasedwouldhavetopassthroughtherecirculation pumpsandlowerreactorinternals toreachthecore.Largepartswouldnotbeabletopassthroughtherecirculation pumps.Althoughnotspecifically

analyzed, theconsequences ofthesmallerpartswouldbeconsistent withtheconsequences ofotherpostulated loosepieces.PART8.13-INSPECTION ACCE<SSCRITERIAThedesignshallconsiderthefollowing inspection accessrequirements:

~Therepairhardwareshallnotadversely impacttheaccesstootherreactorinternals, reactorvesselorECCScomponents.

~Therepairhardwareshallnotinterfere withrefueling operations orotherin-vessel activities.

~Therepairshallberemovable asfrequently aseachoutagewithoutpermanent damagetotherepaircomponents and/orexistinginternals.

~Allrepairpartsshallbereadilyremovable andreplaceable.

~Therepairdesignshallpermitfutureinspection oftherepairhardwarepertherequirements ofReference 5.PART8.13.1-INSPECTION ACCESSCONFORMANCE Thedesignoftherepairisinconformance withallcriterialistedinPartB.13abovebasedonthefollowing:

~Therepairclampshavealowprofileandfitsnuglyagainstthecor'eshroud.~Therepairclampscanberemovedinastraightforward mannerbyreversing theinstallation stepsdiscussed inPartA.1above.PART8.14-CREVICE<SCRITE<RIA Therepairdesignshallbereviewedforcrevicesbetweenrepaircomponents andbetweenrepaircomponents andoriginalstructures toassurethatcriteriaforcrevicesimmunetostresscorrosion crackingacceleration aresatisfied.

PART8.14.1-CREVICESCONIORMANCETherepairdesignhasconsidered crevicesandtheirimpactonstresscorrosion crackingbyusingmaterials whicharehighlyresistant toIntergranular StressCorrosion Cracking(IGSCC).Thematerial's IGSCCresistance isverifiedbytestingperrequirements ofASTMA262PracticeE.PART8.15-MATERIALS CRITE<RIA Allmaterials shallbeinconformance withBWRVIP-02 (Reference 1)requirements.

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PART8.15.1-MATERIALS CONFORMANCE Allmaterials areusedinconformance withBWRVIP-02 (Reference 1)requirements.

Specifically, allrequirements forstainless steelmaterials asspecified inBWRVIP-02 aremetfortherepairmaterials asdiscussed inPartA.2above.PART8.16-MAINTE<NANCE/INSPECTION OFREPAIRHARDWARE~CRITRRIA Thedesignedrepairshallminimizefutureinspections andmaintenance ofrepaircomponents andpermitfutureinspection oftherepairhardware.

PART8.16.1-MAINTENANCE/INSPECTION OFREPAIRHARDWARECONFORMANCE Inspection oftherepairclampsinfuturerefueling outageswillbebasedontherequirements inSection4.2ofBWRVIP-07

[5],"BWRVesselInternals Project,Guidelines forReinspection ofCoreShrouds."

Theinspection willinvolvethevisualinspection oftheoverallclampsandthethreadedpin-to-eccentric andlockingscrew-to-eccentric crimpareastoconfirmnochangefromtheircondition duringthepost-installation inspection PART8.17-IMPACTONTIE-RODHORIZONTAL WELDRE<PAIR~CRITRRITheverticalweldrepairshallnotimpactthecoreshroudtie-rodrepairandthesupporting safety,stressandseismicanalyses(References 6,7and8).PART8.17.1-IMPACTONTIE-RODHORIZONTAL WE<LDRE<PAIR~CONRORMANCR Thesafety,stressandseismicanalysesforthecoreshroudtie-rodrepair(References 6,7and8)werereviewedandevaluated todetermine ifthereisanyimpactfromtheverticalweldrepair.Resultsofthereview/evaluation are:~Nospecificdiscussion ofrequirements fortheshroudverticalweldswasfoundinReferences 6,7and8.However,itisclearthatthedesignandtheanalysesofthetie-rodrepairarebasedontheshroudretaining acylindrical configuration intheeventofcrackingintheverticalwelds.Accordingly, theverticalweldrepairisrequiredtopreservethecylindrical shroudconfiguration forallappliedloadsandloadcombinations.

Asidentified inPartB.2above,thisisoneofthefunctional requirements fortheverticalweldrepair.~Noallowance forcoolantleakagethroughcrackedverticalweldsisconsidered inthesafetyanalysisforthetie-rodrepair(Reference 6).Therefore, theverticalweldrepairisrequiredtolimitverticalweldleakage,incombination withotherleakagesources,towithinacceptable levelsforallplantconditions.

Thisisafunctional requirement fortheverticalweldrepairasstatedinPartB.2above.12of14

~PerReference 8,theseismicfuelloadsaretransmitted directlythroughthetopguideorcoresupportplateringstothetie-rodradialrestraints.

Therefore, itisthestiffness oftheseringsandnotthestiffness oftheshroudcylinders thataffectsthefuelseismicresponse.

~Forashroudcylinderwithfullycrackedverticalweldsandendconditions thatprovidenolateralshearrestraint, thelateralstiffness wouldbereduced.Sinceshroudstiffness isaparameter intheshroudseismicmodel,thisreduction couldimpacttheseismicanalysisresults.However,thispotential impactisnotsignificant sinceforalloftheseismiccasesconsidered inSection5ofReference 8,theHl-H2andH4-H5shroudcylinders havehingedconnections totheadjacentcylinders.

Thishingedconnection providessheartransferbetweentheshroudcylinders andpermitstheshroudcylinders toretaintheiruncracked momentofinertiaandrotational stiffness.

Basedontheabove,theverticalweldrepairhasnoimpactonthetie-rodrepairandthesupporting safety,stressandseismicanalyses.

PARTC-CONCLUSIONS Thissafetyevaluation hasdetermined thattheadditionofverticalweldrepairtotheNMP-1coreshrouddoesnotincreasetheprobability ofoccurrence orconsequences ofanaccidentpreviously evaluated intheNMP-1UpdatedFinalSafetyAnalysisReport(UFSAR)(Ref.

4),doesnotincreasetheprobability ofoccurrence orconsequences ofamalfunction ofequipment important tosafetyevaluated previously intheUFSAR,doesnotcreatethepossibility ofanaccidentormalfunction ofequipment important tosafetyofadifferent typeevaluated previously intheUFSARorreducethemarginofsafetyasdefinedinthebasisforanytechnical specification.

Therefore, itisconcluded thattheadditionofaverticalweldrepairdoesnotconstitute anunreviewed safetyquestion.

PARTD-REFERENCES l.EPRIReport,"BWRVIPVesselandInternals Project,CoreShroudRepairDesignCriteria(BWRVIP-02),"

Revision2,FifthDraftReport,April1988.2.MPRSpecification No.249014-001, "DesignSpecification forNineMilePointNuclearStationUnit1(NMP1)CoreShroudVerticalWeldRepair,"Revision2,December28,1998.13.ASMEBoilerandPressureVesselCode,SectionIII,Division1-Subsection NG,"CoreSupportStructures,"

1989Edition.4.NineMilePointNuclearStationUnit1UpdatedFinalSafetyAnalysisReport,Revision15,November1997.5.EPRIReportTR-105747, "BWRVesselandInternals Project,Guidelines forReinspection ofBWRCoreShrouds(BWRVIP-07),"

February1996.13of14

6.NineMilePointUnit1SafetyEvaluation Number94-080,Rev.1forModification N1-94-003, ReactorCoreShroudRepair.7.GENE-B13-01739-04, "NineMilePointUnit1ShroudRepairHardwareStressAnalysis(NMPCCalculation No.SO-,Vessel-M028),"

Revision0.8.GENE-B13-01739-03, "NineMilePointUnit1NuclearPowerStation,SeismicAnalysis, CoreShroudRepairModification (NMPCCalculation No.SO-Vessel-M027),"Revision0.9.MPR-1966, "NineMilePointUnit1CoreShroudVerticalWeldRepairDesignReport,"December1998,Revision1.PARTE<-ATTACHME<NTS 1.Figures1-1through1-5.14of14 0

6.0I31.25I2.018.501H1HHV5V1V3V6V2Y4'00V8SHROUDHEADFlANGETOPGUIDESUPPORT90.120000V9Y1100V10REPAIRCLAMP{nP)V1263.50.50H6222.13H6A4V13V15V1416COREPLATESUPPORTSHROUDSUPPORTRINGL~ma/144@)l+Wl S1/61/66(~)FigureMNMP-1CoreShroud%'clds

ShroudLocidngScrew"V4VerticalWeldV4PlateCutoutlnShroudiWallLeftBayonetEccentric IIIIIRightBayonetEccentric ThreadedPinl99SNPRASSOCIATES U.S.PATENTPENO9ICMMPR/NlOll0$IXIl0/N/NIMIFigure1-2.NineMilePoint-Unit1ExplodedViewofV4VerticalWeldClampAssembly

'h~t V4VerticalWeldLockingScrewShroudRightBayonetEccentric LeftBayonetEccentric ThreadedPinlalMPRIlnonlyOl/1$/l41ALI)Figure0-3.NineMilePoint-UnitiInstalled V4VerticalWeldClampAssembly1998LIPRASSOOAIES U.S.PA1ENrPEtlDNG 0

VcChzShroudV9/V10'I/eNcalWeldIIjLockingScrew-CutoutinShroud'allV9/V10PlateLeftBayonetEccentric ThreadedPinAightBayonetEccentric LLMPR/N%Ol~01ol/04/00I~Figure1R.NineMilePoint-Unit1ExplodedViewofV9/V10VerticalWeldClampAssemblyl998IIPRASSOCIATES U,S.PAIENrPENOINC

V4VerticalWeldShroudLockingScrewRightBayonetEccentric LeftBayonetEccentric V9/Vt0PlateThreadedPinQMPRtI<0OllOIot/ol/04IMtFigure1-5.NineMilePoint-Unit1Installed V9/V10VerticalWeldClampAssemblyPC199SllPRASSOCIAIES U.S.PATOllPEIIDIIIG

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