ML18040A226
| ML18040A226 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 05/31/1994 |
| From: | ECONOMOS C, LEHNER J, LIN C C BROOKHAVEN NATIONAL LABORATORY |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML17059A382 | List: |
| References | |
| CON-FIN-L-1331 NUDOCS 9408100168 | |
| Download: ML18040A226 (106) | |
Text
TECHNICALEVALUATIONREPORTTECHNICALBASISFORREDUCTIONOFTORUSSHELLCONDENSATIONOSCILLATIONLOADSFORTHENIAGARAMOHAWKPOWERCORPORATIONNINEMILEPOINTUNIT1byC.Economos,J.Lehner,andC.C.LinAccidentAnalysisGroupSafetyandRiskEvaluationDivisionDepartmentofAdvancedTechnologyBrookhavenNationalLaboratoryUpton,NewYork11973January1994RevisedMay1994PreparedforOfficeofNuclearReactorRegulationNuclearRegulatoryCommissionWashington,D.C.20555UnderContractNo.DE-AC02-76CH00016NRCFINL-13119408i001689408051PDRADQCN05000220PDR,
'P4 LISTOFFIGURESFigure1.Figure2.Figure3.MOIpredictedVariationofPressureinComputationCellPlaneofSymmetry-P(x,0,ZO/2).................................19ComparisonofBNLandNMPCEstimatesforPressureAmplitudeReductionFactors...............................~.....20.ResultsofSensitivityStudiesforNMPviatheBNLMethodfImages.............................................210 P
ABSTRACTBNL'sevaluationofthetechnicalbasissubmittedbyNMPCtojustifyareductionintheNMPtorusCOloadsisdocumentedinthisreport.ThereductionwasrequestedbecausethinningoftheNMPtorusshellduetocorrosionimpliesthatstresslevelsinducedbytheseDBAloadswouldexceedallowables.ThetechnicalbasisutilizedinBNL'sreviewincludesaseriesoftopicalreportsprovidedbytheapplicantaswellasresponsestoRAIsgeneratedduringthecourseoftheevaluation.Inaddition,theevaluationinvolvedreviewof.documentsinwhichdevelopmentoftheoriginalCOloadspecificationanditsbasisaredescribed.AlsofactoredintotheevaluationaretheresultsofindependentcalculationsperformedbyBNLtoconfirmtheadequacyoftheapplicant'sanalyticalresults.Finally,thereview'sscopewasexpandedtoincludetheimpactofshellthinningonallDBA-relatedhydrodynamicloads.BNL'sfindingsbasedontheaboveisthattherequestedreductioninCOloadsisappropriateandhasasoundtechnicalbasis.
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TABLEOFCONTENTSSTRACT~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ABLISTOFFIGURES.................,...............0Vl~~LISTOFTABLES.....................................,..........vllLISTOFACRONYMSANDABBREVIATIONS...,.....~~~~~~~~~~~~VillACKNOWLEDGEMENT...........................................lx
1.0INTRODUCTION
ANDBACKGROUND.......................12.0DESCRIPTIONOFTHEPROPOSEDMETHODOLOGY3.0EVALUATIONOFTHEPROPOSEDMETHODOLOGY......~~~~~~~~53.13.2EvaluationBasedontheInitialSublnittal...EvaluationBasedonOtherConsiderations.,3.2.1AcceptabilityofTotalStructuralResponseMethod.........,.....3.2.2BNLConfirmationofGeometryEffectonCOBoundaryPressures........3.221DescriptionoftheMethodology.3.Z2.2GeometricConsiderations.....3.2.Z3PresentationofResults.......3.22.4DiscussionofResults..........5~.5.6..6..7..7..8..94.0IMPACTOFSHELLTHINNINGONOTHERDBA-RELATEDHYDRODYNAMICLOADS.................................,.115.0CONCLUDINGREMARKS...............................,....136.0REFERENCES.............................................14APPENDIXATHEBNLTECHNICALLETTERREPORT...............A-1APPENDIXBTHEBNLINTERNALMEMORANDUM.................B-1APPENDIXCTHEDESCRIBINGEQUATIONSFORTHEBNLMETHODOFIMAGES..e~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~oC-1APPENDIXDTHENRCREQUESTFORADDITIONALINFORMATIONANDTHENMPCRESPONSE~..................,...D-1
LISTOFTABLESTable1.ValuesofParametersUsedtoDefineCalculationCellGeometry....17Table2.ResultsofBNLMOICalculations...........................18 y~v LISTOFACRONYMSANDABBREVIATIONSACABSSBNLBWRBWROGCDICODBADNEFSTFIBALDRMOINEPNMPNMPCNRCPCPUARRAIRFSERSRSSSRVTERTESTLRTSAcceptanceCriteriaAbsoluteSumBrookhavenNationalLaboratoryBoilingWaterReactorBWROwnersGroupContinuumDynamics,Inc.CondensationOscillationDesignBasisAccidentDepartmentofNuclearEnergyFullScaleTestFacilityIntermediateBreakAccidentLoadDefinitionReportMethodofImagesNon-ExceedanceProbabilityNineMilePointNuclearStationUnit1NiagaraMohawkPowerCorporationNuclearRegulatoryCommissionPersonalComputerPlantUniqueAnalysisReportRequestforAdditionalInformationReductionFactor(forpressureamplitude)SafetyEvaluationReportSquareRootoftheSumofSquaresSafety/ReliefValveTechnicalEvaluationReportTeledyneEngineeringServicesTechnicalLetterReportTechnicalSpecification g~I ACKNOWLEDGEMENTTheauthorswouldliketoexpresstheirappreciationtoA.D'Angelo,theNRCLeadEngineerforthisproject.Theguidanceandsuggestionsheprovidedwereinsightfulandconstructive.Hiscontributionswereessentialtothesuccessfulcompletionoftheevaluationdocumentedinthisreport.
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1.0INTRODUCTION
ANDBACKGROUNDThegenericCOloaddefinitionanditsgenesisaredescribedintheMarkILDR.'twassynthesizedfrompressuresrecordedduringtheworstcaseblowdown(TestNumberMS)fromthefirstFSTFtestseries.'histestsimulatedalargeliquidbreakbutwasconductedatapooltemperaturebelowthecurrentTechnicalSpecification(TS)forcontinuousoperation(70'Fvs90-95'F).TheseloadswereapprovedbytheNRC,subjecttotheresultsofadditionalconfirmatorytests.'ncreasedpressureswereobservedintheselatertests'hichwereconductedathigherpooltemperatures(95'FforTestM12).However,theoriginalloadspecificationwasdeemedacceptable'asedonafavorablecomparisonbetweenpredictionsandthestresslevelsobservedduringthehightemperaturetest,Insomecases,thepredictionexceededmeasurementsbyasmuchas150%.TounderstandwhytheLDRloadsexhibitthisconservatismitisnecessarytodescribehowtheloadspecificationisderivedandhowitistobeapplied.Reference6providesadetaileddescriptionofthedesignload'sdevelopment.Herewenoteonlythefollowing:asinglepressuresignaturewasselectedforprocessing(Figure2-6ofReference6).AFourierseriesrepresentationofthissignalwasthendeveloped.ThiswasfollowedbyasomewhatcomplexprocedurethatconvertedtheFouriercoefficientstocorresponding"rigidwall"values.Fromthese,atableofrigidwallFouriercoefficients/pressureamplitudeswasgeneratedasafunctionofdiscretefrequencybands(Table4.4.1-2ofReference1).TheLDRthendirectsthattheseharmonicexcitationsbeapplied,withineachfrequencyband,tostructuralmodelsthatrepresenteachplant-specifictorus,toestablishthestructure'sresponse.Becausethedesignforcingfunctionhasbeendecomposedintoaseriesofdiscreteharmonicexcitations,awayofcombiningthecorrespondingstresseshastobeprescribed.Wenotethatiftheexcitationwasgivenasasingle,continuouspressurewaveformas,forexample,isspecifiedfortheMarkISRVload(Section5.2.2oftheLDR),thisrequirementdoesnotarise.Thus,tocompletetheCOloadspecifi...tion,theLDRrequiresthatthestressesbecombinedbytheABSSmethodwhichisthesimplestandmostconservativeapproach.Thelargemarginsbetweenmeasuredandpredictedstressesnotedaboveareadirectresultofthisapproach.TheexcessiveconservatismofthisapproachwasrecognizedbytheBWROGevenbeforetheLDRloadswereappliedtospecificplants.Accordingly,aseriesofstudieswerecommissionedtodevelopimprovedproceduresthatreducedtheexcessivemarginsbutretainedanappropriatelevelofconservatism.7@'asedonareviewofthesestudies,theNRCstaffagreedthatstrictapplicationoftheABSSmethodwasnotrequiredandrelaxeditsoriginalAC,ForNMP,inparticular,amodifiedCOloadwas,approvedduringreviewoftheirPUAR."ThismodificationinvolvedapplicationoftheABSSmethodtoonlythefourhighestharmonicresponsesandaddition,byaSRSSmethod,oftheremainingones.Notethatthisproceduredoesnotmodifytheforcingfunctionitselfwhichconsistsofthepressureloadsthatareappliedtothewettedtorusboundaries.Therevisedmethoddoes, lrfP however,reducethetotalstressexperiencedbyanyparticularstructuralelementrelativetothatresultingfromfullABSSapplication.FormostBWRplants,useoftheLDRspecifiedABSSmethodwasacceptabledespiteitsinherentconservatism.InthecaseofNMP,however,theneedtoreducetheloadsaroseduetoNMP'snon-prototypicallythintorusshell.Withthepassageoftime,therehasbeenafurtherreductionintheshellthicknessduetocorrosion.ThiscorrosionisacontinuingprocesswhichNMPCanditsconsultantestimateoccursatarateof0.00126inchesperyear."IftheCOloadsarenotreducedevenfurther,controllingstresslevelsareexpectedtoexceedallowablesduring1994.Todelaytheneedtostructurallyreinforcethetorus,NMPChasproposedafurtherreductionintheloadspecification.Thetechnicaljustificationforthisreductionisdescribedandevaluatedintheensuingsections.
~lJt14" 2.0DESCRIPTIONOFTHEPROPOSEDMETHODOLOGYTheinformationsuppliedbytheapplicanttojustifyaloadreductionwastransmittedinavarietyofformsandatvarioustimes.Thegiveandtakebetweenthesesubmittalsandthestaffsresponsesextendedoveraconsiderablechronologicalperiod.Inthissectionwewilldescribetheapplicant'smethodanditsbasisinawaythatparallelsthishistoricaldevelopment.ThemethodsproposedbyNMPCtodemonstratethatareductioninCOloadsisjustifiedwerefirstdescribedintwodocumentspreparedbyaconsultingfirm.'~'hismaterial,aswellasthatprovidedinReference11,constitutedtheinitialsubmittaltotheNRCstaff.Thekeyelementsoftheinformationsuppliedtherewereasfollows:FSTFdataareusedtodemonstratethatsignificantcorrelationoftheCOprocessattheexitoftheeightdowncomersoccursonlyinthe5-6Hzfrequencyrangeandthat,atotherfrequencies,theprocessanditscontributiontoboundarypressuresisrandom.2.ItisnotedthattheFSTFgeometry,whichconsistsofasingle,torus-likebaywitheightdowncomers(cf:Figure3.2-5ofReference2),doesnotcorrectlysimulatetheNMPtorussince,inthelatter,fourdowncomerbaysalternatewitheightdowncomerbays(cf:Figure3ofReference13).TheconsequenceofthisgeometricfeatureisthattheFSTFpressuresareexcessiveforboththefourandeightdowncomerNMPbays.Thisistrueovertheentirefrequencyrangeofthepressuresignatureincludingthesynchronous5-6Hzvalue.3.ItisalsonotedthattheFSTFdoesnotcorrectlysimulateanactualMarkItorusbecauseoftherelativelyrigidendcapswhichactasplanesofsymmetrybetweenadjacentbays.InadditiontoimplyingthatadjacentbayshavethesamenumberofdowncomersastheFSTFasnotedabove,anotherconsequenceofthisgeometricfeatureisthatasynchronouscontributionstothemeasuredpressuresareamplified.4.AnacousticmodelappliedtoanidealizedversionoftheNMPtorus(horizontalcylinderhalffilledwithwater)isdevelopedandutilizedtoquantifytheeffectsenumeratedabove.Theresultsofthisanalysisarepresentedasreductionfactors(cf:Table1ofReference13)thataretobeappliedtotheLDRpressureamplitudes(cf:Table4.4.1-2ofReference1).ThesefactorsdependprimarilyonbaygeometryandthenatureoftheCOprocess:i.e.:whetheritiscoherentorrandom.Thereductionfactorsalsoexhibitaslightdependenceonfrequency.ForuncorrelatedCOtheirvaluesareabout60%and80%forthefourandeightdowncomerarrangements,respectively.ThecorrespondingvaluesforcoherentCOare70%and95%%uo.Theseallrepresentbayaveragedvalues.
J~~I1Jz' 5.Thecorrelatedreductionfactorsaretobeappliedonlyforthe5to6Hzpressureamplitude(about3psia).Forthebalanceofthefrequencyspectrumtheuncorrelatedvaluesaretobeutilized.6.Theproceduretodevelopthestructuralresponse(stresses)totherevisedhydrodynamicloadsisalsoaddressed.Reference13states(p.14)that"thestructuralanalysisshouldbeundertakenaspertheLoadDefinitionReport".TheanalogouscitationfromReference11appearsonpage11.Itstates"total...stresswasdonebyaddingtheabsolutevalueofthefourhighestharmoniccontributorstotheSRSScombinationoftheothers...".SincetheLDRdictatestheuseoftheABSSmethodforcombiningstresses,twocontradictoryproceduresforcombiningstressesarespecifiedinthisoriginalsubmittalaccordingtowhatiscitedinItem6.Thus,inBNL'soriginalevaluation'4thedistinctionbetweentheLDR'sABSSmethodandthealternativeofcombiningonlythefourpeakresponsesbyABSSandtheremainingresponsesbySRSS'ashighlightedandtheacceptabilityoftheproposedmethodmadecontingentontheassumptionthattheABSSmethodwastobeused.ThispositioncarriedoverintotheSERissuedbytheNRC.'ollowingtheissuanceoftheSER,theNMPCtookexceptiontotherequirementthatABSSbeusedtocomputetotalstructuralresponse."ItclarifiedtheambiguityimpliedinItem6bystatingthattheintentwastoutilizethe4ABSS+SRSSmethodaswasdoneintheiroriginalPUAR.'dditionalinformationinsupportofthisapproachwasalsoincludedinthissubmittal.AdescriptionandevaluationofthislaterinformationisincludedinSection3.2.1below.Insummary,therevisedmethodologyconsistsofasetofmuttipliers(Table1ofReference13)thatareusedtoreducetheLDRpressureamplitudes(Table4.4.1-2ofReference1).AllotheraspectsofthemethodareidenticaltothoseusedintheoriginalNMPPUAR."Forconvcnicnccinthcensuingdiscussion,thismethodofcombiningthcindividualharmonicresponseswillbedenotedbythcacronym4ABSS+SRSS.
V~Cgl 3.0EVALVATIONOFTHEPROPOSEDMETHODOLOGY3.1EvaluationBasedontheInitialSubmittalAsindicatedabove,anevaluationbasedontheinitialsubmittalwascompletedanddocumentedviaaBNLTLRearlyin1992.AcopyofthisTLRisincludedinthisreportasAppendixA.Itwasfoundthattheproposedreductionwas"reasonable,conservativeandtechnicallydefensible".ThebasisforthisconclusionrestedprimarilyonBNL'sconcurrencethattheLDRpressureloadswereoverlyconservativeforthereasonscited(therandomnessoftheexcitationformostoftheobservedfrequencyspectrumandthegeometricdifferencesbetweentheFSTFandtheNMPtorus)andtheacceptabilityoftheanalyticalprocedureutilizedtodevelopanappropriatereduction.However,theincorrectassumptionthatitwasNMPC/YES'sintenttodeveloptotalstressesviaanABSSmethodalsoplayedapartindevelopingtheoverallfindinginthatitimpliedasourceofadditionalconservatism.ThispositionwasevenmoreemphaticallystatedintheNRCstaff'sSER.Finally,theTLRhighlightedthefactthatBNLdidnotcriticallyreviewimplementationoftheanalyticalmethodnoraccuracyofthenumericalresultsthatweregenerated.TheconfirmatoryanalysispresentedinSection3.2.2representsanindirectwayofevaluatingthecorrectnessoftheNMPCmethodandresults.Summarizingthissection,thefindingsfromtheinitialevaluationregardingthepressureamplitudereductionfactorsremainqualitativelyvalidbutrequireadditionalconfirmationoftheirquantitativeacceptability.Thisadditionalrequirementaswellasotherconsiderationsthathaveevolvedsincetheissuanceofthestaff'sSER'saddressedinSection3.2.3.2EvaluationBasedonOtherConsiderationsAsaresultofNMPC'sresponsetotheTER,furtherevaluationwasundertakenbasedontheadditionalinformationthatwassuppliedthereandinReferences8,18,19,and20.Themainfocusofthisnewinitiativewastoestablishthesuitabilityofusingthe4ABSS+SRSSmethodincombinationwiththereducedpressureloads.However,becauseitcouldbeanticipatedthatacceptanceofthiscombinationinevitablywouldreduceexistingmargins,thestafffeltthatamorethoroughexaminationofthenewlydevelopedexcitationwasappropriate.Specifically,theNRCformallyrequestedBNLtoexpandthescopeofitsefforttoincludeanindependent,confirmatorysetofcalculationstodemonstratetheloadreducingeffectofthegeometrydifferencescitedearlier(ie:Items2and3listedinSection2.0).Forcompleteness,thedecisionwasalsomadetoincludeanexaminationoftheimpactofreducedshellthicknessontheabilityoftheNMPtorustowithstandallotherhydrodynamic(ie:besidesCO)loads.Inthenextsub-section,theacceptabilityofthemethodproposedtodeveloptorusstructuralresponse(the4ABSS+SRSSmethod)isaddressed.Then,theBNLmethodforestimating 1~lytt, theeffectofgeometryonpressureisdescribedandnumericalresultspresented.Finally,BNL'sfindingsresultingfromexaminationoftheNMPtorusstructuralcapabilityvis-a-visallDBAhydrodynamicloadsarediscussed.3.2.1AcceptabilityofTotalStructuralResponseMethodInSection1.0itwasnotedthattheNRCstaff'soriginalACwererelaxedregardinguseoftheLDRABSSmethodforcombiningstresses.ThebasisforacceptingalessconservativeversionwasdocumentedinanAugust1983BNLInternalMemorandum."AcopyofthismemohasbeenincludedhereasAppendixB.ThemethodapprovedtherewasintendedtobegenericallyapplicabletoallMarkIplantsbuthasbeenutilizedbyrelativelyfewutilitiesotherthanNMPC.TheevaluationwascarriedoutbythelateG.Bienkowski,ofPrincetonUniversityactingasconsultanttotheContainmentSystemsGroupofBNL'sDNE.ItreviewedessentiallythesamedocumentationNMPCsuppliedmorerecently.Usingconventional,industryacceptedstatisticalconsiderations,methodsweredevelopedtheretoobtainimprovedagreementbetweenmeasuredFSTFstructuralresponses(stresses,displacements,forces)andthosepredictedusingtheLDRharmonicpressure".CommontoallthesemethodswasthenotionthatsomewherebetweenpureABSSandpureSRSSexistsawayofcombiningtheresponsesinamorerealisticway.The"NavalSum"P~whichcombinesthetwohighestpeaksbyABSSandtheremainderbySRSS(2ABSS+SRSS)isoneexample.InReference7therecommendedprocedurewas3ABSS+SRSSimplyinganon-exceedanceprobability(NEP)of84%%uo.Althoughimprovedagreementwasdemonstrated,someexceedanceswerefound,primarilyintheareaofmembranestresses.Toprovidesufficientconservatismtoboundallthemeasuredresponses,itwasrecommendedinReference21thattheproposedmethodbemodifiedtothe4ABSS+SRSSmethodthatwasacceptedbythestaffandapprovedforusebyNMPCintheNMPPUAR.Insummary,the4ABSS+SRSSmethodthatNMPChasusedtodeveloptotalstructuralresponsetotheCOexcitationwasapprovedbythestaffearlier.Nothingthathastranspiredsincethatapprovalwarrantswithdrawalofthisapprovaland/ormodificationoftheprocedure.3.2.2BNLConfirmationofGeometryEffectonCOBoundaryPressuresThemethodologyusedbyBNLtocomputeboundaryloadsonsimulatedversionsoftheNMPtorusandtheFSTFduetoCOatdowncomerexitsisdescribedinthissection.Numericalresultsarealsopresentedhere.TheyincludecomparisonswithcorrespondingNMPCresultsandsensitivitystudiesthatexhibitthedependenceoftheloadsonkeygeometricparametersthatcharacterizetheNMPsuppressionpool.
)~lyi15,AqV<<P' 3.2.2.1DescriptionoftheMethodologyThemethodusedderivesfromanapplicationoftheclassicalMethodOfImages(MOI)technique.ThetechniqueisparticularlysuitablefordescribingthehydrodynamicphenomenonoccurringduringtheCOphaseofaDBAblowdown.BNL'smethodisvirtuallyidenticaltothatemployedbytheGeneralElectricCo.toestimateramsheadrelated,SRVhydrodynamicloads(Section3.3.1,ofReference23),ThesoledifferenceisthatarectangulararrayofimagesisusedbyBNLratherthanGE'sdiamondpattern.Thisisbecausecomputerstoragecapacityandexecutiontimeshaveimprovedconsiderablysincethen(1978).Thus,thegreaterefficiencyprovidedbythediamondshapedarrayisunnecessary.WewereabletocarryoutthesecalculationsonaPC(Gateway2000).AbriefdescriptionoftherelevantdescribingequationsusedherearepresentedinAppendixC.Itshouldbenotedthatthesegivethealgorithmfordevelopingthepressureatanypoint(x,y,z)duetotheexcitationinducedbya~siniedowncomer/source.Tocomputethepressureduetomultiplesources,thecomputercodeloopsoverallsourcesandcombinesthepressurecontributionfromeacheitherbyABSSfor"correlated"pressureorbySRSSfor"uncorrelated"results,3.2.2.2GeometricConsiderationsThegeometryoftheFSTFwasmodelledasasingle,rectangularparallelopipedwithplatformXObyZOanddepthYO(seeFigure1).ThespecificvaluesusedfortheseparametersaregiveninTable1andweredevelopedusingtheinformationgiveninReference20asfollows:YOwastakenequaltotheFSTFtorusradius(aofReference20);XO,correspondingtothecircumferentiallengthoftheFSTFbay,wastakentobefourtimesthedowncomerpairspacing(lofReference20);ZO,thelateralwidthofthecomputationcell,wasselectedsothatthecross-sectionalareaofthecellsequaledthatoftheFSTF;ie:wetookZOsuchthat(YO)(ZO)=m(YO)~/2.Fourpairsofsourceswithlateral/radialspacingDS,weresymmetricallylocatedwithinthecelladistanceHOabovethetorusbottom.HOandDSderivefromthevaluesgivenforrand0inReference20todefinethelocation/submergenceofthedowncomerexitplanes.Thissinglecomputationalcellwasutilizedtodevelopestimatesofboththecorrelatedanduncorrelatedpressureloads.ThisisvalidfortheFSTFsince,asnotedearlier,therigidendcapsrepresentplanesofsymmetrysothatasynchronyoftheCOpulsescanonlyoccuramongtheeightdowncomerscontainedwithinthesinglecell.ModellingoftheNMPgeometrydifferedfromthatfortheFSTFbecauseoftheneedtocorrectlyrepresentconditionswhentheCOprocessisasynchronous.IncontrasttothesituationfortheFSTF,whenthisconditionprevailsintheNMPtorusitimpliesthattheCOpulsesatall120downcomers(10bayswith4pairs;10bayswith2pairs)areoutofphaseratherthanjustatthefouroreightlocatedinasinglebay.Theloadreductionthatwouldresultfromsuchalimitednumberofuncorrelatedsourceswouldbeunrealistic.
I~
Inviewoftheabove,twotypesofgeometrywereemployedfortheNMPsimulations.Forthecorrelatedcase,asinglecomputationalcellwasemployedanalogoustothatusedfortheFSTFexceptforthenumberandlocationofthesources/downcomers.Thesewerearrangedsothatthecalculationcellextendedfromthecenter(hence,planeofsymmetry)ofanon-vent,eightdowncomerbaytothecenterofafourdowncomerbay.Thus,onlythreepairsofsourceswereusedforthissimulation.Allotherpertinentdimensionsforthesingle,NMPcomputationalcellaregiveninTable1.ThesevaluesalsoderivefromtheinformationgiveninReference20.ReferringtoTable1,itisinterestingtonotethattheFSTFandNMPgeometriesarecomparableexceptfordowncomerpairclearance(HO)andspacing(DS).Ascanbeseen,theNMPdowncomerexitsaresignificantlyclosertoeachotherandtothebottomofthetorus.ThesegeometricdifferenceshaveasignificantimpactontheboundarypressuresaswillbediscussedinSection3.2.2.4.ForthecaseofuncorrelatedsourcesintheNMP,thegeometrymustreflectthefactthatincoherencebetweendowncomersisnotlimitedtothoseresidentinasingleoreveninapairofbays.Solongasrigidwallsarespecifiedattheendsoftheselectedcalculationcell,coherencebetweenthesourcesinthatcellandthearrayofimagesthatareemployedbytheMOIisimposed.Unlessthiseffectisproperlyaccountedfor,misleadingresultscanbeobtained.ThisisaccomplishedherebymodelingtheNMPtorusasrealisticallyaspossiblewithrespecttothetotalnumberofdowncomers,Asnotedabove,forNMPthisnumberis120.Ourmodellinghasutilizedhalfthisnumberwhichwouldyieldconservativeresults;i.e.:thepressureatanyparticularspatiallocationdecreasesastherigidboundarieswithinwhichincreasingnumbersofuncorrelatedsourcesareembeddedrecedefromthatlocation.Insummary,twotypesofgeometriesareemployedinBNL'scalculations.Forcorrelatedpressures,asinglecellinwhicheitherfourorthreepairsofsources/downcomersarelocatedisused.ForuncorrelatedpressurescorrespondingtoNMP,thecellextendsinthecircumferential(X)directionapproximately180feetcorrespondingto10bays.'achofthesecellshasthreepairsofsourcesclusteredinsuchawaythatthealternating8 8-4patternintheNMPisreproduced(cf:Figure3ofReference13)~TheoriginoftheXcoordinateisatthecenterofoneortheotherofthesebays(bothcalculationsweremadewithnosignificantdifferencefound)correspondingtoaplaneofsymmetry.ForFSTFpressures,thecalculationcellforbothcorrelatedanduncorrelatedresultsisidentical.Thisisconsistentwiththeactualgeometricconfigurationofthefacilityandcorrectlymodelsthepresenceoftherigidwalls.3.2.2.3PresentationofResultsItwasnotedinSection2.0thattheNMPCmethodultimatelyinvolvesreductionoftheLDRCOpressureamplitudesbywhatarereferredtoinReference13as"HarmonicAmplitudeLoadReductionFactors".ThecalculationsperformedhereprovideanalogousreductionfactorsbygeneratingboundarypressuresforthemodeledFSTFduetoaunitexcitationateachsourceandformingtheratiowiththecorrespondingvaluesobtainedwhenidenticalstrengthsourcesarelocatedinasimulatedNMPtorusgeometry.
4' ResultsofBNL'scalculationsaregiveninthreedistinctways.First,themaximumpressurecomputedwithinagivencomputationalcell(PMAX)istabulatedasinTable2.ThetableincludestheresultsofasensitivitystudywherekeygeometricparametershavebeenvariedfromthebasecasevaluesgiveninTable1.Byfocusingonthesepeakvalues,improvedinsightregardingthetrendsassociatedwithchangesingeometryisprovided.InadditiontotabulatingPMAX,thespatialvariationofpressureatthebottomofthecellattheverticalplaneofsymmetrybetweenpairsofdowncomershasbeengeneratedandisplottedinFigure1,Notethatthisfigureincludesanindicationofthecalculationcellgeometryasithasbeensimulatedhere.Figure2comparestheNMPCreductionfactors(RF)withthosedevelopedbyBNL.ThelatterderivefromtheresultsshowninFigure1byformingtheappropriateratios.Finally,graphicalrepresentationofthefindingsfromthesensitivitystudiesisshowninFigure3.3.2.2.4DiscussionofResultsFromtheperspectiveofjustifyingaloadreductionforNMPrelativetotheloadsderivedfromFSTFtests,thekeyfindingisthecomparisonbetweenthevaluesofPMAXobtainedforCasesN1andF1forcorrelatedresultsandN1(U)andF1(U)foruncorrelatedCOsources,Thereductionfactor(RF)impliedbythefirstoftheseisessentiallyunity;thatis,PMAX=1.45forbothCaseF1andCaseN1asindicatedinTable2.Foruncorrelatedsources,RF=0.76sincePMAX=0.42forCaseN1(U)andPMAX=0.55forCaseF1(U).ThecorrespondingvaluesproposedbyNMPC(fromTable1ofReference13)are0.98and0.83.WeconsiderthistobereasonableagreementparticularlywhenthecomparisonshowninFigure2isalsofactoredin,ReferringnowtoFigure1,themostsignificantoftheresultsshownthereisthelargereductioninpressurethatisobtainedwhenthesourcesarenolongercorrelated.EvenfortheFSTF,thepressuresarereducedtoonlyaboutonethirdofthecorrelatedvalues.Interestinglyenough,thisismoreorlesstheArderofmagnitudeofreductioninpressureamplitudebetweenthefundamentalfrequency(about3psifor5Hz)andtheothernon-synchronousvalues(1psimaximum)asindicatedinTable4.4.1-2ofReference1.ComparisonoftheBNLandNMPCvaluesoftheRFsshowninFigure2indicateclearlythattheyareinverygoodagreement.NoteespeciallythattheNMPC'suncorrelatedRFsaremoreconservativethanBNL's.Thatis,theLDRpressureamplitudesarereducedlesswhentheNMPCRF'sareused.SomenonconservatismisexhibitedforcorrelatedRF'sbutthisdifferenceis,atmost,6%.Thesedifferencesareconsideredminorand,inourjudgement,donotinvalidatetheacceptabilityoftheproposedmodifications.Withrespecttothesensitivitystudiesthatwereperformed,wenotefirstthattheyweremotivatedbytheresultobtainedforCaseN2ofTable2correspondingtoacomputationalcellwiththeNMPgeometrybutwithfourratherthanthreepairsofdowncomers.Although Jtr~
thiscasedoesnothavedirectapplicabilityhere,itwasperformedoutofacademicinterestandforthesakeofcompleteness.AscanbeseenbyreferringtoTable2,thevalueofPMAXcorrespondingtoCaseN2(1.66)notonlyexceedsthatforCaseN1(1.45),whichistobeexpected,butalsoexceedsthevaluepredictedforthebasicFSTFcase(CaseF1).Thisincreasecanonlybeattributedtogeometricdifferencessincesourcenumberandstrengthareidenticalforthosetwocases.ThesamesortofdifferenceisexhibitedbetweentheCaseF2(PMAX=1.24)andtheCaseN1(PMAX=1.45)results.Notethattheselattertwocasescorrespondto8 8-4typeconfigurations.Thesefindingswerethemotivationforthesensitivitystudiesthatwereconducted;ie:todeterminewhatfeatureoftheNMPtorusgeometrygivesrisetopressureloadshigherthanthoseexpectedintheFSTFforthesamenumberofdowncomers.AscanbeseenfromtheresultsshowninFigure3,thenotedincreasesareprimarilytheresultofthesignificantlysmallerclearance(7vs7.8ft)thatprevailsintheNMPtorus.OneimplicationofthisfindingisthattheFSTFgeometrywasnotstrictlyapplicableforNMPbothwithrespecttothelatter's8 8downcomerarrangement(aconservatism),butalsowithregardtodowncomerclearance(anon-conservatism)~Thetrade-offbetweenthesetwoopposingeffectssuggeststhattheoriginalNMPdesignloadsweresuitable,notwithstandingthat,totheauthors'nowledge,noadjustmentfortheeffectofreducedclearancewasmadeorconsidered.AmorepositiveinterpretationofthisfindingwouldbethatCOloadscouldbereducedbyanincreaseinclearanceatNMP;ie:byshorteningthelengthofthedowncomers.AccordingtoTable2(CaseN8vsCaseN1),adecreaseinPMAXofalmost20%couldbeachievedbyremoving12inchesfromthedowncomerends.Ofcourse,suchamodificationwouldinvolvesignificantexpensebutmightbeacost-effectivealternativetothestructuralmodificationscurrentlyunderconsiderationbyNMPCintheeventtheybecomenecessary.NotethatareductionofHOimpliesacorrespondingreductionindowncomersubmergencewhichtendstomitigatepoolswellloads(Section3ofReference3)~However,italsopotentiallyreducesthesteamcondensingperformanceofthesuppressionpool.Thusatotalsystemanalysiswouldberequiredtodeterminethemeritofthisconcept.10 I
4.4IMPACTOFSHELLTHINNINMi&RODYNAMICLOADS6ONOTHERDBA-RELATEDTheapproachherewastore-reviewtheNMPCPUARfortheNMPToruswiththefocusonhowthinningofthetorusshellcouldpotentiallyeffecttheearlierevaluation.~Asaresultofthisreview,anRAIwasdevelopedandtransmittedtoNMPC.~NMPC'sresponsetothisRAIwasprovidedtotheNRCstaffvialetterdatedSeptember28,1993.BNLreceivedandreviewedthisinformationinOctoberof1993.Itsfindings"werethat"itwasresponsiveandcomplete.Noopenissuesorconcernsrelatedtothissubmittalwere'dentified."ThecontentoftheRAIandNMPC'sresponseareincludedinthisreportasAppendixD.ThegeneralthrustofthequestionsposedintheRAIwastoconfirmthatsufficientmarginwasavailabletoaccommodatetheincreaseinstresslevelsassociatedwithreducedshellthicknessforalltheloadcasesmandatedbytheNRCstaff'sAC.Atotalof27suchloadcasesarespecifiedasenumeratedinFigures4.3-1,4.3-2and4.3-3ofReference3.TheRAIalsorequestedthatthecontributiontostresslevelduetoeachevent(eg:theDBACOload)beitemizedtodeterminetheirrelativeimportance.Examplesoftheinformationobtainedinthiswayissummarizedbelow.InresponsetothefirstRAIquestion,theapplicantindicatedthatforEventCombination20(thecontrollingloadcase)onlyabout30%ofthetotalstressisduetotheCOload.Mostofthestress(almost60%)stemsfromtheDBAinternalpressureload.Thus,anyreductionintotalstresscanonlybeasmallfractionofthecorrespondingreductioninCOload.Thisclarifiestheseeminglyanomalousresultthatupto60%reductionsinthelatterleadto,atmost,a10%reductionintotalmembranestressasreportedinNMPC'soriginalsubmittal."Anotherquestionaskedthattheloadcombinationinducingthenexthigheststressbeidentified.TheresponseindicatedthistobeEventCombination14,Thiseventcombines,amongotherloads,thosestemmingfromSRVactuationandtheIBACOload."ConsiderablereductionintotalstressrelativetoEventCombination20isreported(from16ksitoabout13ksi)withtheinternalpressurebeingevenmoredominant(almost75%ofthetotal).TheIBACOloadcontributionisonly6%,anamountequaltothatfromSRVactuation,asurprisinglysmallvalue.Insummary,theresponsesindicatethatthemarginbetweenexpectedandallowablestresslevelsforallotherEventCombinationsaremuchgreaterthanforthatcitedasthelimitingcase.Basedonthisinformation,itcanbeconcludedthatthecapabilityoftheNMPtorusItisimportanttonotethattheoriginalIBACOloadisusedherc.ThemodificationrcriucstcdbyNMPCappliesonlytotheDBACOload.11 I4 tomaintainitsintegrityduringpostulatedDBAeventsisassuredprovidedthatthisisdemonstratedforEventCombination20.Finally,duringreviewoftheNMPtorusPUAR,aconcernrelatingtothewayinwhichtheCOloadsareappliedtodeveloptheringgirderstructuralresponse(Section5.0ofReference24)wasidentified.Thisconcernarisesduetotheasymmetryintroducedbythe8 8downcomerarrangement.Specifically,thePUARstatesthatthehalfbaystructuralmodeloftheNMPtorus(Figure3-3ofReference24)isusedfortheringgirderresponsefor"allshelldynamicloads."SincetheaverageCOpressureamplitudesthatareappliedinalternatebaysdifferbymorethan20%,thequestionofhowthegradientacrosstheringgirderwasaccommodatedarose.TheissuewasraisedandresolvedviatelephoneconferencewithNMPCpersonnelandconsultants.Firstitwasestablishedthattheissuehadnotbeenaddressed.Toresolvetheissue,theapplicantcommittedtoutilizingaboundingapproach~whereinthehigher,non-ventbayloadswouldbeappliedonbothsidesoftheringgirdertodevelopthestresseswithintheregionimmediatelyadjacenttothetorusmiterjointandmiteroffset.Sincethisloadingcreatesthehighestbendingmomentacrosswhatis,ineffectarigidconnection,thestructuralresponsewillbemaximized.Weconsiderthisaconservativeand,therefore,acceptableapproach.12 I4 5.0CONCLUDINGREMARKSBasedontheevaluationdocumentedhere,BNLconcludesthatthereductionintheDBACOloadsthathasbeenrequestedbyNMPCisappropriateandtechnicallyjustified.ThegeometricrestraintsimposedbytheFSTFfromwhichtheLDRloadsderivedidintroduceconservatismsthatcansafelybereduced.Theabsenceofcoherenceformostofthefrequencyspectrumisalsoclear.TheCDIanalysisbasedonacousticsrepresentsarationalprocedureforestimatingandquantifyingtheseeffects.Ourindependentcalculationsconfirmthatthisanalysiswascorrectlyimplemented.ThesoleconcernthatwewouldhighlighthererelatestoBWRplantoperatingprocedures/technicalspecifications/emergencyoperatingprocedures.Specifically,itwasnotedintheintroductoryremarksthattheFSTFtestresultsexhibitedanincreasingtrendoftheCOloadswithincreasingpooltemperature.AlthoughtheLDRloadsandtheNMPmodifiedversioncanaccommodatetheobservedincrease,anyfurtherincreaseintheTSfortheinitiationofsuppressionpoolcooling~canpotentiallyinvalidatetheiracceptability.InthisconnectionwenotethatarequesttopermitasubstantialincreaseinthisTSisnowbeingconsideredbytheNRCstaff."WewanttoemphasizeheretheneedtokeeptheconnectionbetweenDBAloadsandplantoperatingconditionsintheforefrontwhenconsideringanyfurthermodificationstocurrentlyacceptabledesignhydrodynamicloads.Additionalevaluationand/oraugmentationoftheexistingsuppressionpoolhydrodynamicdatabasetogetherwithadditionalanalysiscouldverywellbeneededtoprovidesoundjustificationforsuchmodifications.13 I4 6.0REFERENCESGeneralElectricCompany,"MarkIContainmentProgramLoadDefinitionReport,"GETopicalReportNEDO-21888,Revision2,November1981.2.Fitzsimmons,G.W.,etal.,"MarkIContainmentProgramFull-ScaleTestProgramFinalReport,TaskNo.5.11,"GEProprietaryReportNEDE-24539-P,April1979.3.U.S.NuclearRegulatoryCommission,"SafetyEvaluationReport,MarkILongTermProgram,ResolutionofGenericTechnicalActivityA-7,"NUREG-0661,July1980.GeneralElectricCompany,"MarkIContainmentProgramLetterReport:SupplementalFull-ScaleCondensationTestResultsandLoadConfirmation,"MI-LR-81-01-P,April1981.U.S.NuclearRegulatoryCommission,"SafetyEvaluationReport,MarkILongTermProgram,ResolutionofGenericTechnicalActivityA-7,"NUREG-0661,Supplement1,August1982.6.GeneralElectricCompany,"MarkIContainmentProgramAnalysisofFullScaleTestFacilityforCondensationOscillationLoading,"GEReportNEDE-24645,July1979.7.GeneralElectricCompany,"MarkIContainmentProgramEvaluationofHarmonicPhasingforMarkITorusShellCondensationOscillationLoads,"GEReportNEDE-24840(preparedbyStructuralMechanicsAssociates),October1980.8.Kennedy,R.P.,"ResponseFactorsAppropriateforUsewithCOHarmonicResponseCombinationDesignRules,"SMAReport12101.04-R002D,preparedbyStructuralMechanicsAssociatesforGeneralElectric,March1982.9.Kennedy,R.P.,"AStatisticalBasisforLoadFactorsforUsewithCOHarmonicResponseCombinationDesignRules,"SMAReport12101.04-R003D,preparedbyStructuralMechanicsAssociatesforGeneralElectric,March1982.10.Bienkowski,G.,Lehner,J.R.,andEconomos,C.,"TechnicalEvaluationoftheNineMilePointUnit1NuclearGeneratingStationPlantUniqueAnalysisReport,"BNL-04243,September1984.TeledyneEngineeringService,"NineMilePointUnit1ReductioninMarkITorusProgramCondensationOscillationLoadDefinitionandResultingEffectonMinimumShellThicknessRequirements,"TESTR-7353-1,Revision1,April1991.14 lI~,
12.Bliss,D.B.andTeske,M.E.,"FSTFShellCondensationOscillationCorrectionFactors-UncorrelatedVents,"CDIReport79-1,Revision2,preparedbyContinumDynamics,Inc.forGeneralElectric,August1980.13.ContinuumDynamics,Inc.,"ReductionofTorusShellCondensationOscillationHydrodynamicLoadsforNineMilePointUnit1,"CDITechnicalNote90-11,preparedforTeledyneEngineeringServices,November1990.14.Economos,C.,Lehner,J.andLin,C.C.,"EvaluationofNMCTechnicalBasisforReductionofNMPTorusCOLoads,"BNLTechnicalLetterReport,February1992.15.U.S.NuclearRegulatoryCommission,"SafetyEvaluationbytheOfficeofNuclearRegulationRelatedtoProposedDefermentofTorusModificationsNiagaraMohawkPowerCorporationNineMilepointNuclearStationUnitNo.1,DocketNo.50-220,"August1992.16.TeledyneEngineeringServices,"TechnicalResponsetoSafetyEvaluationbytheOfficeofNuclearRegulationRelatedtoProposedDefermentofTorusModificationsNiagaraMohawkPowerCorporationNineMilepointNuclearStationUnitNo.1,DocketNo.50-220,"November1992.17.TeledyneEngineeringServices,"MarkIContainmentProgram,Plant-UniqueAnalysisReportoftheTorusSuppressionChamberforNineMilePointUnit1NuclearGeneratingStation",TESTR-5320-1,Revision1,OctoberSeptember1984.18.NiagaraMohawkPowerCorporation,"ReductioninMarkITorusProgramCondensationOscillationLoadDefinitionandResultingEffectonMinimumShellThicknessRequirements,"PresentationtoNRC,March23,1993.19.Kennedy,R.P.,etal,"StudytoDemonstratetheSRSSCombinedResponsehasgreaterthan84PercentNonexceedanceProbabilityWhentheNewmark-KennedyAcceptanceCriteriaareSatisfied,"GEReportNEDO-24010-03,Supplement3,August1979.20.Bilanin,A.J.,"NRCRequestforDocumentationoftheNineMileCondensationOscillationAcousticTorusLoadReductionAnalysisLimits,"ContinuumDynamicsLetterReportNo.TELEDYNE/0073,April1993.21.Bienkowski,G.,"ReviewoftheValidityofRandomPhasingRulesasAppliedtoCOTorusLoads",InternalBNLMemorandum,August1983.22.Scanlon,R.,ProfessorEmeritus,PrincetonUniversity,PersonalCommunication.15 ItkAll'I 23.GeneralElectricCompany,"MarkIIContainmentDynamicForcingFunctionsInformationReport,"GEReportNEDO-21061,Revision3,June1978.24.TeledyneEngineeringServices,"PlantUniqueAnalysisReportoftheTorusSuppressionChamberforNineMilePointUnit1NuclearGeneratingStation,"TESTechnicalReportTR-5320-1,October1983.25.Triolo,S.andLe,A.,"AuditforMarkIContainmentLongTermProgram-StructuralAnalysisforOperatingReactors,NiagaraMohawkPowerCorporationNineMilePointNuclearStationUnit1",FranklinResearchCenterTechnicalEvaluationReportTER-C5506-331,September1984.26.U.S.NuclearRegulatoryCommission,"RequestforAdditionalInformationRegardingRe-ReviewofNineMilePointNuclearStationUnit1TorusLoadReductionSubmittalofMay14,1991.",August1993.27.TeledyneEngineeringServices,"ResponsetotheNRCRequestforAdditionalInformationRegardingRe-ReviewofMay14,1991TorusLoadReductionSubmittalNiagaraMohawkPowerCorporationNineMilePointNuclearStationUnit1,DocketNo.50-220",TESLetterReport7519-28,September1993.28.BrookhavenNationalLaboratory,"MonthlyBusinessReportforOctober1993-NineMilePoint,Unit1:SuppressionPoolDynamicLoadsRevisedMethodology."29.Attachment1toNMPCLetterDatedNovember30,1993fromC.D.Terry,NMPCtoUSNRCDocumentControlDeskUnderDocketNo.50-220.30.Mintz,S.,"BWRSuppressionPoolTemperatureTechnicalSpecificationLimits.",GeneralElectricReportNEDO-31695.31.U.S.NuclearRegulatoryCommission,"StandardTechnicalSpecificationsGeneralElectricPlant,BWR/4,"NUREG-1433,January1991.16 f/
Table1ValuesofParametersUsedtoDefineCalculationCellGeometryITEMXOYOZODSHOFSTFVALUE19.513.821.78.07.84.956.37.2NMPVALUE19.6(176.4)13.521.26.07.04.965.27.2NOMENCLATUREDSHOlNDPMAXp/XOYOZOeUNITSSPACINGBETWEENDOWNCOMERPAIRSINTHEZDIRECTIONVERTICALDISTANCEBETWEENTORUSBOTTOMANDDOWNCOMEREXITSPACINGBETWEENDOWNCOMERPAIRSINTHEXDIRECTIONNUMBEROFDOWNCOMERPAIRS(SEETABLE2)MAXIMUMPRESSUREIN8DOWNCOMERBAYINFLUENCECOEFFICIENTS-dPMAX/dDS,dPMAX/dYO,etc.RADIALDISTANCETORUSCENTERTODOWNCOMEREXITCENTERSIMULATEDLENGTHOFTORUSBAYDEPTHOFSUPPRESSIONPOOL=TORUSRADIUSSIMULATEDTORUSDIAMETERPOLARCOORDINATEANGLEMEASUREDFROMHORIZONTALTODOWNCOMEREXITCENTERPMAX-SOURCEUNITS(SU)P-SU/FTDS,HO,I,r,XO,YO,ZO-FEET8-DEGREES17 I
Table2ResultsofBNLMOICalculationsCASEF1F1(U)F2YO13.8ZO21.7ND8.0HO7.8PMAX1.450.551.24N1(U)N2N3N4N5N6N7N8N9N1013.512.514.513.521.2176.43021.224.027.06.07.08.06.07.06.08.07.01.450.421.661.251,631.421.391.701.211.341.27Notes:SeeTable1fornomenclatureandunits.Allresultsareforcorrelatedsourcesunlessotherwiseindicatedbythenotation(U)followingtheCaseIdentifierNumber.
I III1~NonventBayA2XOVentBay(NMP)DS:FSTFIPjO+O+O++,'ypicalComputationCell+a+++,s+,'I,--,IIIOnly0+Y=Z=Ox=z=o2.0P'.an~HO~YOSectionA-A1.61.2~CaseN2~CaseF1~CaseN1P0.80.4~CaseF1(U)~CaseN1(U)0.000.51.0X/XO2.0Figure1-BNLMethodofImagesPredictedVariationofPressureintheComputationCellPlaneofSymmetry-P(X,O,ZO/2)19!II l4
'.0BNLRF080.6CorrelatedNMPC////r/X/XO1.0RF0.80.6NMPC~\~srBNLUncorrelatedrr//I/////0.40.00.51.0X/XO1.52.0Figure2-ComparisonofBNLandNMPCEstimatesforPressureAmplitudeReductionFactors20 IJC 2.0PMAX1.00.0125~ppWP'=0.1914YO2.01.00.0P'=-0.037DS2.02.0PMAX1.01.0~~ppP'=-0.25P'=-0.030.07HO0.02024ZO28Figure3-ResultsofSensitivityStudiesforNMPviatheBNLMethodofImagesSolidSymbolsDenoteCaseN1ParametersSeeTable1forNomenclatureandUnits21
I4A-1 4
a~~EvaluationofNMCTechnicalBasisfor~ReductionofNMPTorusCOLoadsC.Economos,J.Lehner,andC.C.Linjanuary1992RevisedFebruary1992~r~SummaBNL'sevaluationofthetechnicalbasissubmittedbyNMCtojustifyareductionintheNMPTorusCOloadsisdocumentedviathisletter.report.Theevaluationincludesareviewofthehistoricaldevelopmentsthatprecededthecurrentsubmittal.ThesearepertinentbecausetheyrepresentthepointofdeparturefortheproposedmodiGcations.BNL'sGndingisthatthemethodologyusedtodemonstratethatareductionintheseloadsisappropriateis,technicallysoundandjustiGestherequestedmodiGcations.BackroundThegenericCOloaddeGnitionanditsgenesisaredescribedintheMarkILDR'.Itwassynthesizedfromthepressuresrecordedduringtheworstcaseblowdown(TestNumberM8)fromtheGrstFSTFtestseries'.Thistestsimulatedalargeliquidbreakbutwasconductedattherelativelylowpooltemperatureof70'F,avalueless'hanthecurrentTechnicalSpeciQcation(TS)forcontinuousoperation(theLCO).TheseloadswereapprovedbytheNRC,subjecttotheresultsofaddi~analconGrmatorytests3.Thepressuresobservedintheselatertests'erehigherforliquidblowdownsconductedatsomewhathigherpooltemperatures.SpeciGcally,TestNumberM12,conductedataninitialpooltemperatureof95F,gaverisetopressuresthatwereabout15%higherthanpeakM8values.Notethatthistemperaturelevelisroughl~eualtothecurrentTSontheLCO(90to95'F)andissomewhatlessIt)anthemohiGedValueof100FthattheBWROGhasrequestedtheNRCtoapprove.Notwithstandingtheincreasedloadsobsertj'edduringTestM12,theoriginalloads'peciQcationwasWundacceptable6basedonafavorablecomparisonbetweenthemeasuredand'.predictedstressNvelsfortheFSTF.Insomecases,thepredictionexceededmeasurementsbyasmuch.as150%%uo'.I'heconservatismoftheLDRloadspeciGcationstemsprimarilyfromtherequirementthatalloftheharmoniccomponentresponsesbeaddedbyabsolutesum.Thisisequivalenttoassumingthattheexcitationcreatedbyoscillationofthesteam-waterinterfaceattheendofeachoftheeightdowncomersissynchronizedovertheentirefrequencyrangethatwasobserved(upto50Hz).ThestaffrecognizedthatthisapproachisconservativeandrelaxedtheACbasedonseverallaterstudiessubmittedbyGEanditsconsultants"9.ForNMP,inparticular,amodiQedCOloadwasapprovedduringreviewoftheirPUAR'.ThismodificationaccountedfortheabsenceofcompletecorrelationbetweenventsbytakingtheabsolutesumofonlythefourhighestharmonicresponsesandaddingtheSRSSof'the~~'SeeListofAbbreviationsfordetinitiono(neronyms.A-2 II
~remainingones.Notethatthisprocedurereducescriticalstressesbutdoesnotexplicitlychangetheforcingfunctionitselfwhichconsistsofthepressureloadingonthesubmergedboundaries.ThebasisforapprovingthisapproachwasthatitstillboundedthemeasuredresponsewhenappliedtotheFSTF..WhenappliedtoNMP,thecriticalstressesintheshellremainedbelowallowables.l/TheneedtoreducetheCOloadsbelowthegenericLDRvaluesarose'becauseofNMP'sthintorusshell.Withthepassageoftime,therehasbeenafurtherreductionintheshellthicknessduetocorrosion.ThisreductionisacontinuingprocesswhichNMCanditsconsultantestimateoccursatarateof.00126inchesperyear".IftheCOloadsarenotchanged,criticalstresslevelsareexpectedtoexceedallowablesduring1994.Todelaytheneedtostructurallyreinforcethetorus,NMChasproposedareductionintheloadspeciGcation.ThetechnicaljustiGcationforthisreductionisdescribedandevaluatedintheensuingsections.DescritionoftheProosedMethodoloThemethodsproposedbyNMCtodemonstratethatareductioninCOloadsisjustiGedaredescribedintwodocumentspreparedbyaconsultingGrm'~".Keyelementsofthepresentationareasfollows:1.FSTFtestdataareusedtodemonstratethatsigniGcantcorrelationoftheCOprocessattheexitoftheeightdowncomersoccursonlyinthe5-6Hzfrequencyrangeandthat,atotherfrequencies,theprocessanditscontributiontothepressuresignatureisrandom.2.3.ItisnotedthattheFSTFtestfacilityisnotprototypicalofanactualMarkItorusbecauseoftheendcapswhich'actasplanesofsymmetrybetweenadjacentbays.ItisclaimedthattheconsequenceofthisgeometricfeatureistiiattheincoherentcontributionstotheobservedpressuresareampliGed.Itisfurther-notedthattheFSTFfacilityisalsonotprototypicaloftheNMPtorussince,inthelatter,fourdowncomerbaysalternatewitheightdowncomerbays".Inthiscaseitisclaimedthattliisgeometricdiscrepancyimpliesthatthe'FSTFpressuresareexcessiveforboththefourandeightdowncomerNMPbays,andthatthisistrueovertheentirefrequencyrangeincludingthesynchronous5-6Hzvalue.4.AnacousticmodelappliedtoanidealizedversionoftheNMPtorus(horizontalcylinderhalffilledwithwater)isdevelopedandutilizedtoquantifytheeffectsenumeratedabove.Theresultsfrom'thisanalysisarepresentedasreductionfactors'hataretobeappliedtotheLDRpressureamplitudes".ThesefactorsdependprimarilyonbaygeometryandthenatureoftheCOprocess,ie.,coherentorrandom.Theyalsoexhibitaslightdependenceonfrequency.Thereductionfactors'reabout60%forthefourdowncomergeometiyand80%fortheeightdowncomerbayconGgurationforuncorrelatedCO,Thecorrespondingfactorsforthecorrelatedcaseareapproximately70%and95%,-respectively.Theserepresentbayaveragedvalues.'Theterm"reductionfactor"isusedhereandinReference12toindicateamultiplieroftheoriginalvalue.A-3 lIt'Ay'4II5'
~5.Correlatedreductionfactorsaretobeappliedonlytothe5-6Hzpressureamplitude.Fortheremainingfrequencyspectrum,uncorrelatedvaluesaretobeutilized.AftertheLDRpressuresarereducedbythesefactors,thestructuralanalysisisto"be.undertakenaspertheLDR.""/~Withrespecttotheoriginalanalysis",theseproceduresyielda4%%uoreductionofthecontrollingstress(membrane)foraneightdowncomerbayanda10%%uoreductionforafourdowncomerbay".Intermsofshellthickness,thesecorrespondtoreductionsof16and44mils,respectively.Thecorrespondingvaluesgiveninamorerecentsubmittal're18and37mils.Itisstatedthere,thatthesecorrespondtoa17%and30%reductionintheLDRCOloads,respectively.EvaluationoftheProosedMethodoloInBNL'sjudgement,thereductionintheCOloadsthatNMChasrequestedare,reasonable,conservative,andtechnicallydefensible.Thebasisforthisconclusionareasfollows:1.TheFSTFdatasupportthenotionthattheCOprocessisrandomovermostofthefrequencyspectrumconsideredintheloadmethods,2.Becauseofthegeometricdifferences,particularlythe4 4downcomerarrangement,thepressureloadsduringaCOblowdownwilltendtobegreaterintheFSTFrelativetotheNMPtorusforthesamethermodynamicQowconditions.3.TheprocedureusedtoquantifytheeffectofItems1and2representsastraightforwardapplicationofaconventionalhydrodynamicmethod.Theresultsarereasonableandprobablyconservativebecauseofthehighsoundspeedusedinthenumerics.WealsoconsidertheassumptionthatacorrelationexistsbetweenbaystobeasigniQcantconservatism.4.TheoverallreductionoftheloadsfromLDRvaluesissigniQcantlylessthanthatapprovedearlierbythestafP.ThisreductionwasfoundacceptablebecauseitwasabletoaccommodateallofthestressesobservedduringtheFSTFtests.ConcludinRemarksTherearethreepointswewanttoemphasizehere.Thefirstisthattheprocedurewehaveevaluatedrepresentsamorerigorous,almostQrstprinciplesway,toaccomplishwhatwasdonebeforeinanapproximateway.Aswealreadynotedinourbackgrounddiscussion,themodificationthatwasutilizedbyNMPearlierdidnotinvolveanychangeintheLDRpressures.ReliefwasobtainedbynotsummingthestressesinducedbyeachandeveryoneoftheQftyharmonicexcitationsbyabsolutesumasrequiredbytheLDRmethodology.ThatthiswasanacceptableprocedurecouldonlybedemonstratedbycomparingpredictedFSTFPe~=Modelingofthetorusashalffilledwithwaterisaminornonconservatism(NWLinMarkIplantsiswellbelowthetoruscenterline),bui.isareasonablesimplificationofananalysiswhichisalreadyquitecomplex.A-4
'lld>>;,'
~stresseswithmeasuredFSTFstresses.Indistinctcontrast,thepresentmethodprovidesreliefbyreducingtheexcitation(pressures)itself.ThesecondpointisthatthebasisforItem4restsonourassumptionthatwhentheapplicantrefersto"LDRvalues"whatismeantarethestressesthatresultbyapplyingthe,LDRpressureamplitudesandthencombiningalloftheindividualpeakstressesbyabsolutesum.Thedocumentsthatwehaveinhandaresomewhatambiguousonthispointanditwould.beprudenttoobtaindocumentedconGrmationthatourinterpretationiscorrect.Finally,wenotethatourreviewoftheanalysisdoesnotincludedirectconfirmationofanyofthenumericalresultsthatwerepresented,e.g.,the:reductionfactors.Itisassumedthatthesederivefromacorrectapplicationofthemethodology.A-5
'IIIS.r References1.GeneralElectricCompany,"MarkIContainmentProgramLoadDefinitionReport,"GeneralElectricTopicalReportNEDO-21888,Revision2,November1981.~r~2.Fitzsimmons,G.W.,etal.,"MarkIContainmentProgramFull-ScaleTestProgramFinalReport,TaskNumber5.11,"GeneralElectricProprietaryReportNEDE-24539-P,April1979.3.U.S.NuclearRegulatoryCommission,"SafetyEvaluationReport,MarkILongTermProgram,ResolutiohofGenericTechnicalActivityA-7,"NUREG-0661,July1980.4GeneralElectricCompany,"MarkIContainmentProgramLetterReport:SupplementalFull-ScaleCondensationTestResultsandLoadConfirmation,"MI-LR-81-01-P,April1981.5.Mintz,S.,"BWRSuppressionPoolTemperatureTechnicalSpecificationLimits,"GeneralElectricReportNEDO-31695,May1989.6.U.S,NuclearRegulatoryCommission,"SafetyEvaluationReport,MarkILongTermProgram,ResolutionofGenericTechnicalActivityA-7,"NUREG-0661,Supplement1,August1982.7."MarkIContainmentProgramEvaluationofHarmonicPhasingforMarkITorusShellCondensationOscillationLoads,"NEDE-24840,preparedbyStructuralMechanicsAssociatesforGeneralElectricCompany,October1980.8.9.Kennedy,R.P.,"ResponseFactorsAppropriateforUsewithCOHarmonicResponseCombinationDesignRules,"SMA12101.04-R002D,preparedbyStructuralMechanicsAssociatesforGeneralElectricCompany,March1982.IKennedy,R.P.,"AStatisticalBasisforLoadFactorsAppropriateforUsewithCOHarmonicResponseCombination'DesignRules,"SMA12101.04-R003D,preparedbyStructuralMechanicsAssociatesforGeneralElectricCompany,March1982.10.11.Bienkowski,G.,Lehner,J.R.andEconomos,C.,"TechnicalEvaluationoftheNineMilePointUnit1NuclearGeneratingStationPlantUniqueAnalysisReport,"BNL-04243,September1984.7"NineMilePointUnit1ReductioninMarkITorusProgramCondensationOscillationLoadDefinitionandResultingEffectonMinimumShellThicknessRequirements,"TechnicalReportTR-7353-1,Revision1,preparedbyTeledyneEngineeringServicesforNiagaraMohawkPowerCorporation,April1991.12."ReductionofTorusShellCondensationOscillationHydrodynamicLoadsforNineMilePointUnit1,"C.D.I.TechnicalNoteNo.90-11,preparedbyContinuumDynamics,Inc.forTeledyneEngineeringServices,November1990.A-6 I
13."FSTFShellCondensationOscillationLoadingCorrectionFactors-UncorrelatedVents,"C.D.I.ReportNo.79-1,Revision2,preparedbyD.B.BlissandM.E.TeskeofContinuumDynamics,Inc.forGeneralElectricCompany,August1980.14.Figure3ofReference12.15.Table1ofReference12.16.Table4.4.1-2ofReference1.17.p.14ofReference12.18.TESReportTR-5230-1,Rev.1,"MarkIContainmentProgram,Plant-UniqueAnalysisReportoftheTorusSuppressionChamberforNineMilePointUnit1NuclearGeneratingStation,"datedSeptember21,1984.19.NMCletterNMP1L-0628fromC.D.Terry(VPNuclearEngineering)toU.S.NRC,datedDecember13,1991.20.Bienkowski,G.,"ReviewoftheValidityofRandomPhasingRulesasAppliedtoCOTorusLoads,"InternalBNLMemo,August1983.A-7 I
LISTOFACRONYMSACBNLAcceptanceCriteriaBrookhavenNationalLaboratoryBWROGBoilingWaterReactorOwnersGroupCOFSTFGELCOLDRNMCNMPNRCPUARSRSSTSCondensationOscillationFullScaleTestFacilityGeneralElectricLimitingConditionforOperationLoadDefinitionReportNiagaraMohawkPowerCorporationNineMilePoint-Unit1NuclearRegulatoryCommissionNormalWaterLevelPlantUniqueAnalysisReportSquareRootoftheSumofSqaresTechnicalSpecificationA-8 Ilf4
'B-1 I
ReviewoftheValidityofRandomPhasingRulesasAppliedtoCOTorusLoadsGeorgeBienkowskiAugust25,1983ContainmentSystemsGroupDepartmentofNuclearEnergyBrookhavenNationalLaboratoryUpton,NewYork11973B-2 l4lS INTRODUCTIONTheLDR<'>specificationforCOTorusloadsisbasedonFSTFdata(primarilytestM-8).Inordertoresolvepotentialuncertaintiesintheconservatismofthedata,supplementarytestsM-11BandM-12wereconductedintheFSTFfacility.WhileM-12wasnottotallyboundedbytheLDRspecification,thestafffeltthattheLDRprocedureofsummingtheabsolutevaluesoftheharmoniccomponentswassufficientlyconservativetoboundanyuncertaintiesinthedata(SupplementtoMarkISER-NUREG-0661).<'>ManyoftheindividualMarkIplantshavechosentodeviatefromtheLDRprocedureandhavereducedtheconservatisminherentintheabsolutesumloadapplicationthroughsomeuseofrandomphasingbetweenharmonicsoftheLDRCOrigid-wallpressurespecification.ThebasisforallofthesealternateloadapplicationprocedurescomesfromGEreportNEDE-24840<'~andsomesubsequentreportsbyStructuralMechanicAssociates(SMA12101.04-RODID,SMA12101.04-ROOZD,SMA12101,04-R003D).<4">Whileindividualplantsobtainareductioninloadduetotheeifectofrandomphasingindifferentmatter,agenericevaluationofthebasefortheseproceduresisnecessaryinordertoestablishtheadequacyofeachplant'sexceptiontotheAcceptanceCriteria.A.ReviewofGENEDE24840,"EvaluationofHarmonicPhasingforMarkITorus"Theprimaryobjectiveofthisreportistoreducetheexcessiveconservatisminthetorusshellresponseduetotheuseoftheabsolutesumofharmonicamplitudes.Thereportdemonstrates,byexaminingthroughMonteCarlocalculationboththeFSTFdataandanactualfacility(OysterCreek),thatrandomphasingleadstoamorerealisticresponse.Thereportfurtherproposesadesignrulethatisrelativelyeasytoapplyandprovides90%confidenceof50%non-exceedanceprobability.Thereportfurtherjustifiesthischoiceasbeingappropriatetopreserve,attheresponselevel,thenon-exceedanceprobabilityorthedegreeofconservatismcontainedwithintheloaddata.Sevenresponses(BDCaxialandhoopstress,BDCradialdisplacement,andfourcolumnforces)attheFSTFfacilityareanalyzedonthreedifferentbases:(a)Fouriercomponentsofthemeasuredspatially-averagedpressuretimehistoriesover5(second)intervalsofRunNumberM-8areusedasloadinput;(b)MonteCarlotrialsbasedonrandomphasingbetweenthe50harmoniccomponentsrepresentingthehistoriesin(a)areapplied;(c)MonteCarlotrialsusingrandomphasingamongthe50harmonicsoftheLDRloadspecificationareused.ThepeakresponsesresultingfromthesesanalysesarethencomparedtothemeasuredpeaksintheFSTFtests.Acomparisonoftheresultsof(a)tothemeasuredresponsessuggeststhatthemodellingofthefacilityandarepresentationofthedataisadequatetomatchthecolumnforcesandradialdisplacementbutyieldspeakmembranestressesthatarefrom13%to30%(hoop)toolow.Thereportgoesintoanumberofexplanationsforthereasonsforthisdiscrepancy.Whilemostofthesuggestedcauseswouldnotbeapplicableinarealfacility,thesuggestionB-3
\I~
thatshellmembranestresseswillrespondtolocalpressureswhiletheinputloadhasbeenaveraged,canbeassumedtobetransferabletoaplantcalculation.Thispotentialnon-conservatismiseventuallyrecognizedinthefinaldesignrule.Thepeakresponsesatthe50%NEPlevelresultingfrom200MonteCarlotrialswithrandomphasingbetweenharmonics(optionb)generallyeitherboundtheresultsusingactualphasingorareveryclosetothem.Theratiooftheresponses,basedon(a)dividedbythe50%NEPresultof(b)rangesfrom0.88forthecolumnforcesto1.03fortheradialdisplacement,withthemembranestressesat0.94.The50%NEPresultof(b)comesclosertoboundingtheexperimentaldatabutthemembranestressesarestilllow(9%axialand15%hoop).The200MonteCarlotrialsarealsoperformedfortheLDRspecification.Becauseofsomeadditionalconservatismsintheloadharmonicamplitudes,the50%NEPnowboundsthecolumnforcesandradialdisplacementsubstantially,essentiallymatchestheaxialmembranestress,andunderpredictstheFSTFpeakhoopstressbyonlyabout6%.Thereportthenproceedstoperform200MonteCarloresponsecalculationsforthemodelofarealfacility(OysterCreek).ClearlyinthisexerciseonlytheLDRharmonicscanreasonablybeappliedandnodirectcomparisontoexperimentscanbeperformed.Theresults,however,suggestthatthecumulativeprobabilitydistributions(CDP's)fortherealfacilityareverysimilartothosefortheFSTFfacility.Theratioofthe50%NEPleveltotheabsolutesumisaboutthesameasinFSTFandliesinthevicinityof50%forthemonitoredresponses.Thereport'ssubsequentdiscussionoftheproperwaytocombinestressesisoutsidethescopeofthisreviewandnotdirectlyrelevanttotheloadspecificationissue.Onthebasisoftheinformationsummarizedabove,thereportrecommendsasimpledesignrulethatwillyield90%confidenceof50%NEP,Theresultsof(b)and(c)forFSTF,andthecalculationsforOysterCreekdemonstratethattakinganabsolutesumofthethreehighestharmonics(atresponselevel)coupledtoasquarerootofthesumofthesquares(SRSS)oftheremainingharmonicsalwaysboundsandcloselyapproximatesthe50%NEPlevel.Thereport,therefore,suggeststheuseofthissimplealgorithmfortheadditionoftheharmoniccomponentsinthefrequencydomain.Inordertoprovideadditionalconservatisminarealfacility,theharmonicloadcomponentsthatspanastructuralnaturalfrequencyaretunedtothenaturalfrequencyratherthanappliedattheaveragefrequencyintheinterval.AcomparisonoftheapplicationofthisdesignruletotheFSTFfacility(wherefrequencytuningisnotused)tothemeasureddatashowsthatallpeakresponsesarebound,except'hehoopstresswhichisabout5%low.Thereportsuggestsanumberofconservatismsintheloadingthatwouldcompensateforthissmalldiscrepancy.Theprimaryeffectsuggestedisrelatedtothedampingof2%usedinanalysis.Inarealfacility,whereloadsarecombinedandarethushigher,the2%dampingisaconservativerepresentationofthestructureandwouldthusleadtoconservativeresponses.B-4
/
B.ReviewofSMAreport12101.04-R001D,R002DandR003DReportSMA12101.04-R001D,"EvaluationofFSTFtestsM12andM11BCondensationLoadsandResponses,"wasnotavailableandthusnotdirectlyreviewed.Themajorresultsandconclusionsofthatreportare,however,summarizedinSMA12101.04R002D,andwerefoundtobeconsistentwithboththeoriginalreportNEDE-24840andtheFSTFSupplementalTestLetterReportM1-LR-81-01P.ReportSMA12101.04-R002D,"ResponseFactorsAppropriateforUsewithCOHarmonicResponseCombinationDesignRules,"summarizesalloftheconclusionofNEDE-24820andupdatesthecomparisontoincludeFSTFtestsM12andM11B.WhentestM12isincludedinthecomparison,thedesignruleapplicationoftheLDRharmonicstotheFSTFtorusunderestimatespeakmeasuredmembraneaxialstressby11%andunderestimatesthehoopstressby14%,whileboundingtheotherresponses.Onthebasisofthiscomparison,thereportsuggestsmodifyingthedesignrulebyusinga"responsefactor:R,=1.0forotherresponses.Inaddition,thereportaddsanadditionaldesignruleforthosecircumstanceswherethecombinationofabsolutesumandSRSSisnotconvenient,suchasinthetimedomain.Inthiscasethereportstatesthata90%confidenceof50%NEPlevelcanbeachievedbymultiplyingthepeakresponseresultingfromasinglerandomphasedtrialby1.15.Notethatformembranestressesandstrainsthereisanadditional1.15"responsefactor"describedabove,Theconclusionsprovidecriteriafordesignanalysesalongthelinesjustdiscussed,butanadditionalsimplificationofneglectingharmoniccomponentsabove30HZissuggestedforstructureswithsimilarnaturalfrequencycontenttotheFSTForOysterCreek.ReportSMA12101.04-R003D,"StatisticalBasisforLoadFactorsAppropriateforUsewithCOHarmonicResponseCombinationRules,"reiteratesthedesignrulesdescribedabove.Inaddition,recognizingpotentialuncertaintiesinthedata,thereportattemptstoprovidesomejustificationforneglectinganyadditionalfactortoprovideadequateconservatism.Thereportshowsthat,consideringthespecificationisaresultofthreedatapoints(M8,M12,M11B),theincreaseinresponsetoachieve75%confidenceof84%NEPrangesfrom2%forinsidecolumnforceto33%forthehoopstress.ThereportfurtherquotesanunreferencedcommunicationfromDr.AlanBilaninasstatingafactorof1.33fortheratiooftheFSTFdatatothatexpectedinarealfulltorus.Thiseffectispurportedtobetheresultoftherigidendeffects,butnofurtherexplanationisprovided.InAppendixA,thiseffectisexamined.Weconcludethatforthesefrequenciesthatarenotcorrelatedbetweenbays,theFSTFshouldproduce32%to35%higherloadsthanwouldexistinarealfacility.AnexaminationoftheFSTFdata(inSupplementedLetterReportM1-LR-81-01-P)showsthatonlythefundamentalfrequencynear6Hzshowsanycorrelationbetweendowncomers.Ifoneassumescorrelationbetweenbaysatthatfrequencyandrandomphasingbetweenbaysatallotherfrequencies,theoverallconservatismfortheaveragepressuremaybeaslowas17%,whileattheresponseleveltheFSTFconservatismwillrangeform18%forthehoopstressto38%%uofortheaxialstress.Ifwenowbalancethisversusthemaximumexpecteduncertaintyfactorforhoopstress(1.33)asinreportR003D,wecouldexpectaB-5 I~~)~t%~
maximumdegreeofnonconservatismofabout13%.Thisisnotseriousfortwodistinctreasons.Theadditionalconservatismsassociatedwiththerealstructureduetothetuningofharmoniccomponentstothenaturalfrequenciesandtheclosermatchtothe2%dampingfactorcaneasilycompensatefortheslightnonconservatism.Secondly,theuncertaintyestimate,usingonlythreepeakresponsesformthetestsM8,M11BandM12isprobablyexcessivelyconservative.Ifoneused1secondaveragedRMSpressuresfrom8-secondhighmassflowintervals,aswasdoneintheSERSupplement,theratioofmeantopeakR=0.72andthestandarddeviationiso,=0.172.Theresultantloadorresponseat2o,fromthemean(nowprovidingaveryhighconfidencelevelofnon-exceedence)isonly7%abovethedesignruleandcanbeeasilycompensatedbythe1.18conservatismfactorfortheFSTF.C.SummaryandConclusionsOnthebasisofthereviewofthesereportsthestaffconcludesthatadirectapplicationofdesignrulesasgiveninreportSMA12101.04R002Donpage41orinreportSMA12101.04-R003Donpages1-2isacceptable.Ifharmonicsabove30Hzareneglected,assuggestedforstructuressimilartoFSTForOysterCreek,aspecificjustificationintheformtorusresponsefrequencycharacteristicmustbepresented.AnyvariationthatproducesatleastashigharatioofresponsetothatproducedbyabsolutesumasthehighestobservedintheFSTFandOysterCreekanalyses(63%)isalsoacceptable.UsingthedesignruleasinitiallystatedonNEDE-24840(withoutthe1.15factorforshellstresses)isnotacceptable,butamodificationusing4harmonicssummedabsolutelyaddedtotheremainingsummedSRSSismarginallyacceptable,providedthereportedshellstressesarenotwithinafewpercentofallowables.Theadditionof1harmonic,tobesummedabsolutely,providesonlyabouta10%increaseintheresponsesratherthanthe15%neededtoboundFSTFmeasurements.Theeffectissufficientlysmall,however,thatfurtherevaluationwouldbenecessaryonlyintheeventtheresultantstressesapproachedallowablevaluesveryclosely.Insummary,thestafffindstheanalysispresentedintheseriesofreportsreasonable.Anyconservativeapplicationofthoseresultsisthusacceptable.Thedirectapplicationofthedesignrules,asstatedinthefinalreportSMA12101-04-R003Disconsideredadequatelyconservative.Anyalternateisacceptable,provideditsapplicationtoFSTFdatawouldboundallthemeasuredstresses.B-6 1'I I~IC-1 IR METHODOFIMAGESBythemethodofimages,theimagelocationsaredefinedbyx;=2L~x,y;=2H;~y,z),=2'zgi,j,k=0,~1,+2...ThetankdimensionsareL,H,Dinthex,yandzdirectionrespectively.yistheverticaldirection,y=0isthetankbottomandy=Histhefreesurface.Theoriginofthecoordinatesystemisatthelowerleftcorner.xyandz,definethelocationofthesourcewithstrengthP,.Thepotentialatanypoint(x,y,z)canbeexpressedasDefine$g=x0-xpg,=-x0-x,g,=-x,+x,g4=xa+xgi=-yo+ygz--2H-y,-y,7t,=y,+y,g,=2H+y0-y1=zoz>(20z03="0-z04=0+ZandliiBnan(&,.4,)'+(4Hj+g)'2D1yklmn~(2L,Q,)+(4H,.+2H+g)+(2D~Q)C-2 4~~l sothatNNKLNlP=P.ZZZZAWheii+lilhi4EZ(4i-I;;up(1)-"jsOmal+aihhlPJ,!asiMilPJWwhereNI=4NI=2NK=4NK=2ifififi~1ifi=1kw1k=1andL,MandNdefinethenumberofimagesusedintheimagearray.C-3
~e~f~'~E APPENDIXDTHENRC.REQUESTFORADDITIONALINFORMATION--'::-',;'.A'ND'THENMPCRESPONSE I'aji gVN~IAAII$HIAOAIIAICWhWkMWR5COlfPOllAYIONl30IPLAINFIELDROAD.SYRAE.NY.I3212'ELEPHONEI3'I5I47*15IISeptember29,lNMPrr.0VU.B.NuclearReguhgozyCommissionAttn:DociunentContxolDesk%aswzlgton,DC35'B:NineMilePointUzIh1DoclretNo.$0-220DPR43S~ed:MCRcqucdfarAAQheati+onzzcofozzBeguSaBe~&wqfAVqrMltPorcNuclearSafesVn01ToneLoadctfazsSubmittalq/"MtyX4gNNByletterdatedAuguat26,l993,theNRCnqIIestodadditional'nnecessarytocompletethere-mvievofam'ayl4,1991re@estfoeducethecondensationoscillationloadsintheNineMihPointUnitITorus.Attachmezltltothislprovidesourresponsetotherequestedinfarntatha.pyoiI+~anyquestimIs~QgthezIMponsctpleasecontact~DavidELh5rat(315)428-7029.VerytrulyyorC.D;-TerryVicepzeideat-NuclearipzlecrizIgxc:RcgiolQ1Adlni51tslzatorRcg4ÃiIMr.B.Norris,SeniorReaMentInspectorMr.R.A.Capra,Director,projectNzeetorateX-i,NRRMr.D.3.BzinRznan,8caiorprojectManatpr,NRRRecozdsMIzlagemezIt0-2
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..g~~RESPONSETOTHENRCREQADBXHONALPiFORIVtATKONRERE-M',VIEWOFMAT14,1TORUSLOADREBUCHONAJSNIAGARAMOHAWKPOWERCOMjNEMIlUEPOP%MJCLEARSTATIO90CKEYNG.S{}-2207FORORATIONUNl'O.1R8dD-39$:68266'l-ZL'-O'C
~<~-!tP LetterReport7519-28,Rev.1September17,1993~AttachmentPage1SERVtCESpgyle'Tt~tltOWNtN&iC4NHoInSectian3.3,1aftheNinebaflePointPlant-UniqueTorusSuppressionChamber(TeledyneEngineeringSerRev.1;September21,19S4),itisstatedthatcantraforthetorusshellfsthatwhichcombinesOBACOwfpressure(P),deadweight(M)andtheOBE(Case20).thefol'lowingadditionalfnformationand/arclarifithisstatement:nalysisReportofthefees{TES)TR-5320-1,linglaadcambfnatfanhtheOBAhydrostaticheHRCstaffrequestsationwithrespecttoQhatfractionofthetota1shellstress(membrane,local,etc.)derivesfromtheCOloadingtfromthePlaadf97Etc.FarEventCombfnatfan20,ElementNo.19(theostlimitingelement),thestressesfromeachof'hecantrfbutingloasareasfollows:OriginalAnalysis,UnreducedCmembranepercentStressoi'l}~xLMembranePercent+Bond'9of&51:M&CaLOeadweightOBESeismicInternalPressure(QBA):Total1)7562059,219&2K.16,150(16,025)10.951.3%57.0%'100.051;8122079,72216,751(16,618)10.P41.2X58.0XMJ5100.(4CodeAllowableStress16,500'4,750herepart(TR-7353-1)ulatedafterallthesasaresuaraed,Theseaddingtheprincipal5QhksThestressesinparenthesesareframtandaretheprincipalstressescalcomponentstressesframthefaurloadaarelowerthanthetotalsobtainedstressesfromeachloadcase.D-49L'-602667-ZE'-QC
~lrar$,
LatterReport7519-28,Rev.1September17,1993AttachmentPage2IJN'%ERvCESW~oYNI~IKWCKCWNRfterCase20,whatloadcombinationinvolvingnexthfgheststressfnthetorusshell2WhatpstressisduetaCQ2hmmne:ThenextcontrollingeventcombinationisEvelieitfngflelentHo.19,whichincludesdeainternalpressure,SRUandIHACO.Thestrecontributfngloadsareasfollows:COloadsinducesthercentagaofthetotaltCaibfnatfon14forwefght,08Esefsmfc,sasfromeachoftheMembranepercentStressofMB1~aLNeabrano+Bend'g~UPercentofZetaLOeadwe)ght08KSoismfcLnternalPressure(lSA)SRV1,7562059,928821'3.534(13,232)13.0%1,5L73.4%6.0X100.OSCodeAllowableStress16,500$@Q!Thestressesinparenthesesarethcalculatedafterallthecol'ponantstrescasesaresummed.Thoseara,'owerthanaddingtheprfncfpalstressesframeach1,81220710,4702,385~i'll16470(15,148)24,75011.0%1.3%83,6%14,5'00.l7Iipr'incfpalstressesesfromthafiveloadhototalsobtainedbyloadcase,vfngbothCOandSNitforthiscaso2kfaftingelement19,ation14,Seeanswer'Whatistheworstcasaloadcombfnatfaninvoloads'hatarethestresslave>sandtheirs18mme:Theworstcaseloadcombfnatfon,fortheinvolvingbothCOandSRVloadsisEventCondftoQuestion2.D-5
~>~it,,~,~'4 LetterReport7619-28,Rev.1September17,1993AttachmentPage3SERVICESNVSCHQf%CUP~QKWNOcwlQWo4.QhatfstheworstcaseloadcombinationforthenotfnvolveC07Howarethestressesforthatthinnfngofthetorusshall2Howdotheycornstresses'mm:TheworstcaseeventcombinationthatdoesnoCambfnatian18farElementHo.l9,whichfncsefsmfc1andpoolswell,Thestressesfromealoadsareasfollows;torusshellthatdoescaseaffectedbythearewiththeCase20involveCQisEventudesdeadweight,OBEhofthecontrfbut1ngHlabranaStressNeabrane+8endfngOeadwefghtOBESefsmfcTotalCodeAllowableStress1,756205MKR71929(7,812)16,50011812207k2JQ.S,222(8,103)24,760fhgysThestressesfnparenthesesarethcalcu'latedaftera)1thecomponentstloadcasesaresummed.ThesearelobtafnedbyaddingtheprfncfpalstressThesestrlsseswouldincreaseslightlyduettorusshell.However,ascanbeseen,approxfmatolyhalftheEventCambfnatfan20swouldcontrolbyawidemarg1n.\ReferringnowtoSection5.3ofTESTR-7353-1,Rev.provfdethefallowfngfnformatfon/ciarfffcatfon:5.IsthIstatementthat"...EventCamb1natfovalidforboth8and4downcomerbays'owfsBQSSE:Yes.ItfsestablfshedbycomparingthesCoebfnatfonspresentedherein.(Seeresponse6.HhatshellthfcknessfsusedtacalculateeachlevelstabulatedfnthissectfanThnaMfJ::Theor1gfnalthickness1sused,t0.46inchprincipalstressesessesfromthethreewerthanthetotalssfromeachloadcase.thethfnnfngofthethesestressesareresses,sothelattar2(January14,1992),20...fscontrolling"thisestablfshed7ressesfromtheEventoquestion8).afthe"actual"stressD-699'd j4 LetterRaport7519-28,Rev.1September17,1993AttachmentPago4ITthmzae:Yes.Itauldbethesame.Isthesplitinstressesduetothevarioidenticalforthethinnershel1case?Iffractionaldistribution,scantHbutingloadsitisnot,state'thl8.Isthesplitinstressesduetothevariascontributingloadsidenticalfartha4derncomarbeycases?Iitisnot,statethefractionaldistribution?km)nil'.:FaradventCombination20,BeatentNo.19,withreducedCO,thestressesframeachofthecontributingloadsaasfollows:ReducedC0,SOowncamerQaysOeadweightOBESeismicInternalPressure(OBA)TotalCadeAIIovableStressHeehraneStress~D1,756'205g,z)gMBZ)5,522{15,452)16,500PercentofU8aL)1.3%1.3'A59-4%MMK100.0XHeibrane+Band'g~Q1,8122079,722~0.16,122()6,044)24,750Percentotll..P).3%60.3%~5100.%ReducadCO,4OelecaeerBaysHoebranaPercentStressat&%ELZSalHeabranlPercent+Send'gof'Ml~aLGeaheightOBKSeisaicInternalPressure(QSA)Tota1,7562059,2)9M2614,529()4,460}12.)X,).4%63.5'5~5100.N1,8122079,722M2B/,15,116()5~040))2.Ã).4%64.3%~El100.(4CadeAllowableStress16,50024,750therepgrt(TR-7353-I)culatadafteralltheasesaresumaed.Theseyaddingtheprincipal5gia!Thestressesinparenthesesarefroandaretheprincipalstressesccomponentstressesframthefavrloadcarelaierthanthetotalsobtainedstressesfromeachloadcase.I60IdD-7LT:68266'-0C-6<
0~<,l%p~g LetterReport75}9-28.RevSeptemberl7,1993AttachmentPago59.Pravfdetheequfvalentresponsetaquestfondawncaaarbays.hmsz:EventCombfnatfon20fstheonlycasefnvoIvfnextcontrallfngeventcombfnatfanfsEventfnc)udesISACO,Thisfsalsotheworstcfnvalv$ngbathCQandSRYloads.Sfncothosoughtfsanlyfar'BACO,therearenochvaluesforthelBACOresultsforEventCombfsay,thora'fsnadfffsrantfatfonbatmenthe.'oreventcambfnatiansotherthanthe:rsvfsedTheresultsarepresentedfn'guestfan..2~.I~yygygOITILaOYNtIhCSNL?N+E~and3farthe4g08ACOlaads.TheCombfnatfonl4whichsIQvontCONhfnatfonloadreductfanbefngngestotheorfgfnalatfanl4.Thatistaand8.4amceaerbays.":,"2EventComhfnatfanRQ.D-8 e~I