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{{#Wiki_filter:REACTORCOOLANTSYSTEMASYMMETRICLOCALOADEVALUATIONST.LUCIEUNIT1-DOCKETNO.50-335)farch3,1980 SUI&fARY,InMay1975theNRCStaffwasinformedbyapressurizedwaterreactorlicenseethatloadsresultingfromahypotheticalruptureofthereactorcoolantcoldlegpipeintheimmediatevicinityofthereactorpressurevessel(RPV)mayhavebeenunderestimated.InNovember1975theStaffagreedthattheseloadsshouldbeconsideredandevaluatedon,agenericbasis.IFloridaPower&Light'sresponsetotheStaff'sletterofNovember26,1975indicatedthatthesupportsystemdesignincorporatedthereactionforcesassociatedwiththelargearbitraryreactorcoolantpiperuptures,andthatfurther,ithadbeenshowntoacceptablyaccommodatetheadditionalloadsassociatedwithdifferentialpxessureswithinthereactorcavityas,showninAppendix3HoftheFinalSafetyAnalysisReport.TheStaffrequestedthatfurtherinternalasymmetricload(IAL)evaluationsbeconducted.FP&LsletterofFebruary9,1976documentstheCompany'scommitmentstoevaluatethereactorvesselsupportcapabilityforthelimit-ingbreak,acommitmentwhichisrestatedinSupplement2totheUnit1SafetyEvaluationReport(SER),datedHarch1,1976.InSeptember1977FP&LtransmittedtotheNRCareportassessingthemarginindesignofthevesselsupportswhentheinternalasymmetricloadsareaddedtoallpreviousloads.Thereportconcludedthatthesupportswouldadequatelywithstandalltheloadings.However,sincetheanalysisdidnotaccountforgapsbetweenthevesselandthecorebarrel,andalsothevesselandthesupportstructures,ananalysiswasinitiatedatthesametimetoaccountfortheseeffects.TheStaff'sletterofFebruary16,1978requestedthattheevaulationsconductedtodatebeexpandedinscopetoincludeanassessmentofthereactorpressurevessel,fuelassembliesandinternals,controlelementassemblies,primarycoolantpipingandattachedECCSpiping,allprimarysystemsupports,andthebiologicalandsecondaryshieldwallsforaspectrumofbreaksintheprimarysystem.FP&LsMarch1978responsestatedthatitsAugust1977reportwasfullyresponsivetotheStaff'sSERrequirement,thattheSt.Lucie1designwasacceptableandthatthelargeinstantaneouspipebreaksbeingpostulatedweieoverlyconservative.TheresponsewentontosaythatFP&LwouldpursueadditionalanalysesoncetheStaffapprovedtheanalyticalmethodsusedintheAugust1977report.Thisreplynotwith-standing,FP&LbeingsympatheticwiththeStaff'sdesiretoassessanypotentialrisktopublichealthandsafetyfrompostulatedevents,expandedtheanalysisreferredtoabove,toalsoassesstheadditionalitemsidentifiedbytheStaff.
{{#Wiki_filter:REACTORCOOLANTSYSTEMASYMMETRIC LOCALOADEVALUATION ST.LUCIEUNIT1-DOCKETNO.50-335)farch3,1980 SUI&fARY, InMay1975theNRCStaffwasinformedbyapressurized waterreactorlicenseethatloadsresulting fromahypothetical ruptureofthereactorcoolantcoldlegpipeintheimmediate vicinityofthereactorpressurevessel(RPV)mayhavebeenunderestimated.
Thisreportdiscussestheresultsofthisexpandedanalysis.Thecombina-tionofthrust,external,andinternalasymmetricloadsresultingfromtheinletpipecircumferentialbreakpresentthelargestloadtothevesselsupportsamongthosethatwouldensuefromanyofthedesignbasisbreakslistedinAppendix3EIofthePSAR.Theresultsconfirmthatthevesselsupportswilladequatelywithstandalltheloadsresultingfromthepostulatedcircumferentialbreakinthevesselinletpipe.Thecoldlegguillotinebreakinthecavityisthebeakwhichresultsinthelargestloadingofthevesselsupports.There-forethevesselsupportsareclearlyadequateforallotherbreaklocations.ThisreaffirmstheconclusionsoftheAugust1977report.Resultsalsoshowthatallsupportsfortheprimarysystemareadequateforallbreaklocations,thatthestressesintheintactprimarypipingaridattachedlinesaresufficientlylowtoensureperformanceofintendedfunc-tions,andthatthebiologicalshieldwallperformsitsintendedfunction.Thesecondaryshieldwallisdesignedforpostulatedprimarysystemruptureswithinthesteamgeneratorsubcompartments.Theanalysesoftheadequacyoffuelassembliesinternals,andcontrolelementassembliesisinprogress.ResultsareexpectedinJulyof1980.TheStaff,atameetinginJanuary1980,furtherrequestedthatseismicloadsbeseparatelyidentified.Allresultspresentedherein,aswellastheAugust1977xeport,includetheSRSScombinationofLOCAandseismicloads,consistentwiththerequirementofHUREG-0484.PorthosecombinationsdesignseismicloadshavebeenusedandareherebyattachedforusebytheStaff.Inallcases,designseismicloadsareconsiderablyhigherthancalculatedpeakseismicloads.Qualitatively,thesmalldisplacementsobservedforthevesselandcorebarrelfortheworstbreakanalyzed,stronglysuggeststhattheanalysesnowinprogressofthefuel/internalsandCED>fswillindicateacceptableresults.ItmustalsobenotedthatsincethesubmittaloftheAugust1977reporttotheStaff,additionalworkhasbeenreported,tosupportPP&LscontentionthatthetypesofinstantaneouspipebreaksbeingpostulatedbytheStaffareexcessivelyconservative.
InNovember1975theStaffagreedthattheseloadsshouldbeconsidered andevaluated on,agenericbasis.IFloridaPower&Light'sresponsetotheStaff'sletterofNovember26,1975indicated thatthesupportsystemdesignincorporated thereactionforcesassociated withthelargearbitrary reactorcoolantpiperuptures, andthatfurther,ithadbeenshowntoacceptably accommodate theadditional loadsassociated withdifferential pxessures withinthereactorcavityas,showninAppendix3HoftheFinalSafetyAnalysisReport.TheStaffrequested thatfurtherinternalasymmetric load(IAL)evaluations beconducted.
l.0INTRODUCTIONDuringapostulatedlossofcoolantaccidentintheformofacircumferentialpiperuptureattheinletnozzleofthereactorpressurevessel,adecompressionofthereactorpressurevesseloccursoverashortperiodoftime.Decompressionwavesoriginated.atthepostulatedbreaktravelaroundtheinletplenumandpropa-gatedownwardalongthedowncomerannulus.Thefinitetimerequiredbythedecompressiondisturbancestotravelaboutthevesselcausesatransientpxessuredifferentialfieldtobecreatedacrossthecoresupportbarrel(CSB)andthevesselinnersurface.Thisfieldimposesatransientasymmetricloadingonthecore-support-barrelaswellasthevesselitself.Sincethepostulatedpipebreakislocatedwithinthebiologicalshieldwall,theblowdownfluidflash-ingintothereactorcavityalsocausesatransientpressurizationactingonthevessel.Thisexternalpressurizationisalsoasymmetric.Theinternalasymmetricloading(IAL)andtheexternalasymmetricloadingactinthesamedirectionforbreaksoccurringinthecoldlegpiping.Forbreaksinthehotlegs,theinternalasymmetricloadis.virtuallyabsentinthehorizontaldirection,hencethetwoloadsareadditiveintheverticaldirectiononly.Theseloadingsaretransmittedtothereactorvesselsupportsystem.Theresultantreactionforcesatthesupportinterfacesmustbeconsideredintheevaluationoftheadequacyofthesuppoxtsystemtogetherwiththethrustloadresultingfromthebreak,otheroperatingloads,andpostulatedseismicloads.Theseismicloadsandnormaloperatingloads,aswellastheEALhavebeenpreviouslyanalyzedinAppendix3HoftheFinalSafetyAnalysisReport.BreaksoutsidecavitycanresultinIALimposedonthereactorpressurevesselandinternals,andinEALonthe-reactorcoolantpumpandsteamgenerators.Forthebreaksoutsidethecavity,theadequacyoftheprimarysystemsupportsisassessedforfullbreaksatappropriateprima~systemlocations.Thecavitybreaksaredeterminingbreaksfortheassess-.mentoftheadequacyofpipingattachedtotheprimarysystempiping.Thecircumferentialpiperuptureattheinletnozzleofthereactorpressurevesselisdeterminedtobethedesignbasisbreakfortheevaluationofthevesselsupportadequacy.Abreakattheoutletnozzlewouldnotproduceahorizontalasymmetricpressureloadingtothevessel.ConsistentwiththeFinalSafetyAnalysisReport,a4.0sq.ft.coldlegguillotinebreakattheinletnozzleischosenfortheanalysesofthevesselsupportadequacy.
FP&LsletterofFebruary9,1976documents theCompany's commitments toevaluatethereactorvesselsupportcapability forthelimit-ingbreak,acommitment whichisrestatedinSupplement 2totheUnit1SafetyEvaluation Report(SER),datedHarch1,1976.InSeptember 1977FP&Ltransmitted totheNRCareportassessing themarginindesignofthevesselsupportswhentheinternalasymmetric loadsareaddedtoallpreviousloads.Thereportconcluded thatthesupportswouldadequately withstand alltheloadings.
2.0METHODOPANALYSIS2.1ReactorVesselSuortsThe.adequacyofthereactorvesselsupportsisevaluatedbydeterminingtheloadsactingonthepximarysystemwhichresultfromapostulatedbreakattheinletcoldlegnozzle;theresponseoftheprimarysystemtotheapplicationoftheseloads;andthereactionforcesgeneratedbythis=responseatthereactorvesselsupports.Theloadsactingontheprimarysystemconsistofnormalplusseismicloads,thethrustload,externalasymmetricloads,andinternalasymmetricloads.Thelatterthreearecombinedintruetimehistoryfashion,addedtothenormalloadsreactions,thenthexesul-tantreactionloadsatthesupportsarecombinedwithdesignreactionloadsresultingfromthepostulatedseismic(SSE)eventsbySRSStechniques,toobtaintheoverallreactionloadateachofthesupports.Designseismicloadsareprovidedforeachprimarysystemsupportinthethreeorthogonaldirec-.tionsinTable1.Itshouldbeemphasizedthatcomputedpeakseismicloadsareingeneralsubstantiallylessthanthedesignseismicloads;thusprovidinganelementofconservatisminthisanalysis.Table2givesasamplecomparisonofcalculatedanddesignseismicloadsatrepresentativelocations.Thefollowingsubsectionsdescribethemethodologyemployedtoevaluateeachofthethrust,externalasymmetricandinternalasymmetricloads.Inherentintheeyaulationoftheseloadsisthedeteminationofthetime.requiredtoopenupthebreaktotheareabeinganalyzed.2.1.1BreakOpeningTimeandThrustLoadsTheSt.Lucieplantprimarycoolantpiping'inthevicinityofthevesselisrestrainedfromunlimitedmotionfollowingcompleteseveranceintheportionwithinthecavitybyrestraintsintheprimaryshieldwallpenetrationsandwireropesaroundthereactorcoolantpumps.Thisrestrainingsystemhasbeenprevious-lydescribedintheFSAR,Followinganarbitrarilyassumedinstantaneousseveranceofthepipeatthenozzle,thetwoendsofthebrokenpipeseparateundertheactionofthethrustimposedbytheinstantaneoustensionreleasefollowedbytheblowdownoftheescap-ingfluid,andformacombinedbreakareawhichvarieswithtimeasgiveninthefollowingequation:
However,sincetheanalysisdidnotaccountforgapsbetweenthevesselandthecorebarrel,andalsothevesselandthesupportstructures, ananalysiswasinitiated atthesametimetoaccountfortheseeffects.TheStaff'sletterofFebruary16,1978requested thattheevaulations conducted todatebeexpandedinscopetoincludeanassessment ofthereactorpressurevessel,fuelassemblies andinternals, controlelementassemblies, primarycoolantpipingandattachedECCSpiping,allprimarysystemsupports, andthebiological andsecondary shieldwallsforaspectrumofbreaksintheprimarysystem.FP&LsMarch1978responsestatedthatitsAugust1977reportwasfullyresponsive totheStaff'sSERrequirement, thattheSt.Lucie1designwasacceptable andthatthelargeinstantaneous pipebreaksbeingpostulated weieoverlyconservative.
mR.SX(T)2.Bnmg(R.+R)t(v)=<5+2Rjm-(--s'v.2g)f-whereRiandRaretheinnerandouterpiperadii,t0isthepipethz.ckness,xistheaxialsepanationofthetwoendswhichvarie'swithtime7,andg=cos2R.i(2)whereinyistheradialseparationofthetwobrokenendswhichalsovarieswithtime.Thisequationissolvediniterativefashiontogetherwiththeequationforthecombinedtensionreleaseandblowdownforce,givenbelowV(T)2F(x)P(v)A+p(x)A(v)-dlpdlg(3)toyieldthecorrectforcingfunctionandbreakareaasafunctionoftime.Inequation(3),Pandpdarethepressureandfluiddensityinthe3xschargeleg,respectively,Aisthecross-sectionalareaofthepipe,VthebloBdownvelocity,andA(7)isdefinedin(1)above.Themotionofthepipingsystemundertheapplicationoftheforcegivenby(3),iscomputedbymodellingthe'ischargeleg,thepump,andthecrossoverlegwithanel@to-plasticfiniteelementcomputerprogram,PLAST-consideringthesteamgeneratorandthevesseltoremainmotionless.Resultsoftheanalysesindicatethat-atleast18msec.arenecessaryforthepipeendstoseparatetheoverallareaof4.0sq.ft.refermdtointheFSAR.Thisanalysisalsoindicatesthatasaresultofplasticrotationatthepump,itispossibleforthepipeendstoseparatefurther,toamaximumareaof7.78sq.ft.Thetimerequiredforthisareatobeachieved,however,wouldbeinexcessof25msec.ThelongertimerequiredforopeningthelargerbreakinsuresthattheIALresult-ingfromthetwobreaksarevirtuallyidentical.Thelargerbreakdoeshoweverresultinalargerexternal horizontalasymmetricload(externalverticalasym-metricloadsarevirtuallyidenticalforthetwobreaks).Sincethe4.0sq.ft.breakhadbeenone'fthedesignbasisbreaksintheFSAR,allanalysesusedthatbreakarea.However,considerationisgiventowhetherthesystemiscapableofaccommodat-ingthelargerbreak.Asdiscussedinthesubsequentsection,thesystemisinfactadequateforthelargestofthebreaks.2.1.2ExternalAsymmetricPressureLoads(ReactorCavity)ThereactorsubcompartmentanalysisforSt.LucieUnit81hadbeenperfoimedforstipulatedLOCAconditionsincludinga4.0sq.ft.coldlegguillotinebreak,andtheresultshadbeensubmittedtotheNRC.intheFSARandapprovedbytheNRCduringthecourseoftheoperatinglicensereview.Theresultsforthe4.0sq.ft.coldlegguillotinebreak,asreportedinReference2,havebeendirectlyusedin'thepresentstudy.Thisresults.inconservatismoftheanalysissincethecavityresponsehadbeen,predicatedonabreakopeningtimeof10msec,whereas18msec.isneededtoachievethissizebreak.Thepeakexternalasymmetricforcesacrossthereactorvessel,thatwouldresultfromthelarger7.78sq..ft..break,wouldbeapproximately40percentlarger.Thisispredicatedonaratioof1.39betweenpeakandaverageenergyflowtothecavityresultingfroma7.78sq.ft.anda4.0sq.ft.coldlegbreakrespectively.Intheoriginalanalysis,however,twoelementsofconservatismhadbeenintroduced.First,themassandenergyreleaseshadbeenincreasedby10percentandsecond,allinsulationhadbeenassumedtoreamininplaceinthereactorcavityandventareasforthepurposesofvolumeandventareacalculationsinthemathematicalmodel.Theinsulationintheuppercavityreacheswouldbecrushedagainstthevesseluponcavitypressurization,resultinginanincreasedvolumeofapproximately15-20percent.Hence,realisticmodelingoftheinsulationbehavior,coupledwithremovalofthe10percentconservatisminthemassandenergyreleasewouldresultinapre-dictedexternalasymmetricpressureloadandcavitypressureloadfroma7.78sq.ft.breakwhichisonly15to20percenthigherthanthoseconservativelypre-dicted.
TheresponsewentontosaythatFP&Lwouldpursueadditional analysesoncetheStaffapprovedtheanalytical methodsusedintheAugust1977report.Thisreplynotwith-standing, FP&Lbeingsympathetic withtheStaff'sdesiretoassessanypotential risktopublichealthandsafetyfrompostulated events,expandedtheanalysisreferredtoabove,toalsoassesstheadditional itemsidentified bytheStaff.
2.1.3InternalAsymmetricPressuxeLoadsThemodelusedtodeterminethepressurefieldateverypointintheprimarysystemfollowingthepostu-latedprimarysystembreaks,fromwhichtheinternalasymmetricforcesonthevesselandcoresupportbarrelarededuced,isshowninFigurel.TheRELAP-4-thexmalhydrauliccodeisusedtocompute3/thethermodynamicpropertiesinthemodelvolumesandjunctions.ResultsoftheRELAP-4modelhavebeencomparedtoresultsachieved.bymodellingthesystemwithWHAM-6-fortheperiodoftimeduxingwhichthelattercanbeappliedwithconfidence,whichisalsotheperiodoftimeofinterest.,Figure2showsthemodelemployedforWHAM-6.AsimilarWHAMmodelandassumptionsinitsuse,hadbeenp~viouslysubmittedtotheStaffintheAugust1977report.Theresultsofthetwomodelsaxeingoodagreement,withRELAP-4predictingalargerpressuredifferentialacrossthecoresupportbarrel.Resultsoftheinternalasymmetricloadsanalysisindicatethatthepeakforcesacrossthecoresupportbarrelandthevesselarevirtuallyinsensitivetothebreakarea,butextremelysensitivetobeakopeningtimes.Forinstance,achangeinaxeafrom1sq.ft.requiring8msec.toopentoapproximately9.81sq.ft.(completedouble-endedareabreak)withanopeningtime.of36msec.,onlyresultsina2to3percentincreaseinpeakinternalasymmetxicloads,whereasadecreaseinopeningtimefrom36msec.to1msec.forthefullbreakbringsaboutathreefoldincreaseininternalasymmetricload.2.1.,4VesselandPrimarySystemStructuralModelAnon-linearelastictimehistorydynamicanalysisofthree-dimensionalmathematicalmodelofthereactorcoolantsystemincludingdetailsofthereactorinternals,pressurevessel,supports,andpipingwasperformedforthepostulatedpipebreaktoprovidereactorvesselsupportreaction,forces.ThestructuralmodelemployedisshowninFigures3(a)and3(b).Thismodelisthree-dimensionalandhas981totalstaticdegreesoffxeedomand77mass.degreesoffreedom.Thereactorvesselandallinternalcomponentsaremo'delledatinternalandsupportinterfaces.
Thisreportdiscusses theresultsofthisexpandedanalysis.
TheSTRUDL-computercodegeneratesthecondensed5/stiffnessmatrixusedinthedynamic'analysisfromthephysicaldefinitionofthestructure.Hydrodynamiceffects,includingbothvirtualmassandannulareffectsareaccountedforinthecouplingbetweentheRPVandtheCSB,andbetweentheCSBandthecoreshroud.Thehydrodyamic(added)massmatrixisevaluatedusingtheADifASS-code..ThedyanmicanalysistodeterminethesystyyresponsewasperformedusingthecomputercodeDAGS-andDFORCE-.ThereactorpressurevesselsupportsystemisdescribedintheFSAR.ThemodellingofthesteelportionofthesupportisidenticaltothatdescribedintheFSARinAppendix3H.Thebasicmodelofthebiologicalshieldwallisalsoidentical.However,amorerefine(analysisisemployedforthelatter,utilizingaNASTRAN-nonlinearsolutionprocedureemployingquadrilateralandtriangularplanestressconcretecrackingfiniteelements,insteadoftheSTARDYNEmethodofsolutiondescribedinAppendix3HoftheFSAR.2.2ReactorCoolantPiinConnectedPinandOtherRCSSuorts2.2.1SteamGeneratorSupportsOutsidethereactorcavity,breakshavebeenassumedatappropriatelocations.TheRCSsupportsmostaffectedarethelowersteamgeneratorsupports.Theprimarysystemmodelisanalyzedonanelasticbasisforbothhotlegandcoldlegbreaks,thehotlegbreakatthesteamgeneratorinletbeingthedeterminingeventfortheSteamGeneratorsupport.Thisanalysisisastaticanalysiswhichemploysthecompu(p)code51EC-21(HareIslandpipingflexibilitycode)-.BothLOCAanddes'ignseismicloadsareincludedintheanalysis.2.2.2ECCSandOtherConnectedPipingTheanalysisofthestressesgeneratedintheECCSlinesandotherlinesattachedtotheprimaxyloopinvolvedatwostepprocess.First,thetimehistoriesofthedis-placementsaregeneratedateachnozzleattachingsaidpipingtotheprimaryloop.The"worst"timehistory,irrespectiveofthelocationatwhichisoccursis appliedtothelinewhichbyconfigurationandotherloading(normalandseismic)wouldresultinthehigheststresses.ThestressesinducedbyLOCAmotionsforthisparticularconfigurationareadded-topreviouslycomputednormalandseismic(SRSS)stresses.ThedeterminingbreakforECCSlineevalua-tionisthecoldlegnozzlebreakinthecavity.2.2.3ReactorCoolantPipingThestructuralmodelfortheprimarysystemisalsoutilizedtodeterminethestressconditionsintheintactportionofthereactorcoolantloop.3.0RESULTSOFTHEANALYSES3.1VesselSuortsTheloadscalculatedforeachreactorvesselsupportbythemethodoutlinedinSection2.1.4arereportedinTable3forthebreakchosenfortheanalysis;i.e.,the4.0sq.ft.coldlegbreakattheinletnozzle;forarangeofreactorvesselsupportstiffnesses.Thisrangecoversthepossiblevaluesoftheoverallstiffnessoftheindividual'actorvesselsupports,therealvaluebeingsomewherebetweenthetwoextremes.Itisnotpossibletoquantifythestiffnessvaluemorepreciselysincethemodellingoftheboundaryconditionrepresentingembeddedsteelinthebiologicalshieldissubjecttovariation.Inthesupportanalyseshowever,thehigherloadsresultingfromtheuseofthehigheststiffness,havebeenutilized.Thisinsuresagainthattheabsolutemaximumloadpersupportiscomputed.Inreality,lowervaluesareexpected.ThecapabilityofthereactorvesselsupportsisgiveninFigure4andTable4respectivelyfortheRPVsupportpadcapabilityandtheweakestlinkinthesteelsupport/biolo-gicalshieldstructure.Sincethecapabilityofthesupportsexceedthemaximumloadscomputedforthegivenbreak,itisconcludedthattheexist-ingsupportsystemisadequateforthatbreak.AsstatedinSection2.1,itispossiblethat,asaconsequenceofthebrokendischargelinerotationaboutthepump,alargerbreakareacouldformwithinthecavity,uptoamaximumof7.78sq.ft.Thislargerbreakarea,requiringaproportion-atelylongertimetoopen,hasvirtuallynoeffectonthrustandinternalasymmetricloads,butwouldincreasethehorizontalexternalasymmetricloadbyapproximately15-20percentoverthat usedintheanalysis,asexplainedinSection2.1.2.TheEALrepresentsapproximately40percentoftheoverallload.Hence,a20percentincreaseinthisloadwouldresultinlessthana10percentincreaseintheoverallloading.FromTable4andFigure4,itcanbeseenthatthisincreasewouldbeaccommodatedbythemarginsexistinginthesupportsystem.Itisthereforeconcludedthatthereactor'esselsupportscanwithstandthelargestbreakinthecoldlegpipingwithinthecavity.SincecoldlegbreaksoutsidethecavitydonotproduceEALloadsandsincethe'IALisvirtuallyunaffectedbytheareaofthebreakasexplainedinSection2.1.3,itisalsoconclu-dedthatthereactorvesselsupportsarecapableofwithstandinganyloadresultingfrompostulatedrupturesoutsidethecavity.Adetailedanalysisofthereactorloadsresultingfromhotlegbreakswithinthecavityhasnotbeenperformed.Themasonsareasfollows:thestiffnessofthehotleg,pipecombinedwiththesteamgeneratorrestrainingaction,resultsinabreakareawithinthecavitywhichissmallerthanthecoldlegbreakarea,henceresultingEALwouldbelowerthancalculatedforthecoldlegbreak;althoughthethrustforceinitiallywouldbelarger,theIALwouldnotbecolinearwiththrustandEAL,butwouldinfactbeapproximatelyorthogonaltothem.Theresultanthorizontalloadsonthevesselsupportstherefore,wouldclearlybesmaller.Forinstance,thereactionsatreactorvesselsupports,duetoahotlegbreakhavebeencomparedtothereactionsduetoacoldlegbreakforthrustandsubcompartmentpressureonly.HorizontalHotLeBreak(Kis)HorizontalColdLeBreak(Kis)ColdLegSptHotLegSpt427032703275Althoughtheloadonthecoldlegsupportismoresevereforahot.legbreakthanforacoldlegbreak,whentheeffectsofinternalasymmetricloads-areadded,thecoldlegbreakwillgovern.Verticalloadswouldbeofthesame'orderofthoseexperiencedasaresultofcoldlegbreaks,andthecapacityofthesupportsystemtoaccommodateverticalloadsissignificantlyhigherthanitshorizontalcapability.Henceclearlythereactorvesselsupportsystemisalsocapableofwithstandingtheeffectsofpostulatedhotlegbreaksinsideandoutsidethereactorcavity.
Thecombina-tionofthrust,external, andinternalasymmetric loadsresulting fromtheinletpipecircumferential breakpresentthelargestloadtothevesselsupportsamongthosethatwouldensuefromanyofthedesignbasisbreakslistedinAppendix3EIofthePSAR.Theresultsconfirmthatthevesselsupportswilladequately withstand alltheloadsresulting fromthepostulated circumferential breakinthevesselinletpipe.Thecoldlegguillotine breakinthecavityisthebeakwhichresultsinthelargestloadingofthevesselsupports.
Asimilarconclusionhadbeen,reachedinourAugust1977report.DifferencesinmaximumloadsreportedhereinfromthosereportedintheAugust1977reportaretwofold.TheAugust1977reportdidnotconsiderinternalgapsorgapsbetween'hesupportpadsandthesupportstructure.TheAugust1977reportconsideredthereforethatallloadedsupportswouldbeloadedsimultaneouslyandsharetheloadequally.Theagreementoftheoverallloading.betweenthepresentandtheAugust1977results,confirmthattheapproachtakenin1977toassesstheloadswasnotunreasonable.3.2OtherRCSSuortsTheonlysupportsontheprimarysystem,otherthanthevesselsupports,arethesteamgeneratorsupports.Resultsoftheanalysesoftheloadsimposedonthesesupportsfrombothhotandcoldlegbreaksinthesystemincombinationwithseismicloads,indicatedthatnoneofthedesignloadshavebeenexceed-ed,withexceptionoftheloadsonthefourholdownboltsatthevesselendofthesteamgeneratorslidingbaseandtheslidingbaseitself.ThecomputedanddesignloadsareshowninTable5.Individualexaminationoftheslidingbase,thebolts,andboltanchorageshoweverindicatesthatallcanacceptablywithstandtheappliedloads.Itisthereforeconclu-dedthattheexistingsupportsdesignisadeq'uate.3.3ReactorCoolantPiinTable6reportstheelasticallycalculatedpiperupture-andseismicloadsonintactreactorcoolantpipingassociatedwiththebrokenloopfortheworstbreak,whichisthecoldleg.guillotinebreakatthevesselsafeend.ExaminationofthistablerevealsthatallloadsfallwithintheallowableloadswiththeexceptionoftheloadattheRCPdischargenozzle,whichexceedtheallowablebyabout,l3percent,onanelasticbasis.Sincethisanalysis~ispredicatedona4.0sq.ft.coldlegbreak,bytheargumentspresentedinSection3.1,considerationofthelargestbreakthatcouldoccuratthevesselsafeend;i.e.,7.78sq.ft.,requiresthatanincreaseinloadoflessthan10percentbeexaminedtoassessthea'dequacyofthecoolantpiping.Suchanincrease'canbereadilyaccommodatedattheRCPsuctionandRVoutletnozzles.TheRCPdischargewouldbemoreoverstressed(onanelasticbasis)andtheRVinletwouldbeveryslightlyoverstressed.SinceonlythefluidretainingintegrityofthiscoolantpipingneedstobemaintainedduringthepostulatedLOCA,ananalysisconductedonanelasto-plasticbasiswouldconcludethatthis integritywouldbemaintainedatthosenozzles.Sincetheamountofoverstressingcalculatedonanelasticbasisisrelativelysmall,aplasticanalysiswasnotconsiderednecessary.Duringtheperformanceofthisparticular'analysisitwascalculatedthatthesnubbersonthereactorcoolantpumpsareoverstressed.Thesesnubbe~arenotneededfortheseevents.Howevertheirfailurecouldaffecttheresults.Hence,theanalysiswasrepeatedbytakingnoaccountofthesnubbers.ResultsarealsoreportedinTable6~Ascanbeclearlyseen,theeffectofthepresenceorabsenceofthesnubbersisnegligible.3.4ECCSandConnectedPiinThestressescomputedfromtheanalysisdescribedinSection2.2.2arewithin10percentoftheallowable,andhenceitisconcludedthattheECCSpipingandotherpipingconnectedtotheprimaryloop,isnotadverselyaffectedbythepostulatedevent.Table7comparesthepeakcomputedstresses,whichincludenomalandseismicloadstotheallowablestresses.Themarginexistingbetweenpeakstressescalculatedonanelasticbasisandstressesthatwouldbeallowedwithinanelasto-plasticanalysisfurtherindicatesthatthisattachedpipingwouldbeabletowithstandtheimposedloadsfromthe7.78sq.ft.largercoldlegguillotinebreak.3.5SeismicLoads,PursuanttotheStaff'srequestattheJanuary16,1980meeting,Table1providesthedesignseismicloadsatthevarioussupportpointsintheReactorCoolantSystem.3.6ControlElementAssembliesAlthoughtheanalysisoftheControlElementDrivesresponsetopostulatedLOCAeventsisinprogress,butwillnotbecomple-teduntilJuly1980,i'tisgermanetopointoutthattheCEAsarenotneededforbreaks'intheRCSwhichexceed0.5sq.ft.Theassumptionofacompleteguillotinewillresultinbreakslargerthan0.5sq.ft.  
There-forethevesselsupportsareclearlyadequateforallotherbreaklocations.
Thisreaffirms theconclusions oftheAugust1977report.Resultsalsoshowthatallsupportsfortheprimarysystemareadequateforallbreaklocations, thatthestressesintheintactprimarypipingaridattachedlinesaresufficiently lowtoensureperformance ofintendedfunc-tions,andthatthebiological shieldwallperformsitsintendedfunction.
Thesecondary shieldwallisdesignedforpostulated primarysystemruptureswithinthesteamgenerator subcompartments.
Theanalysesoftheadequacyoffuelassemblies internals, andcontrolelementassemblies isinprogress.
ResultsareexpectedinJulyof1980.TheStaff,atameetinginJanuary1980,furtherrequested thatseismicloadsbeseparately identified.
Allresultspresented herein,aswellastheAugust1977xeport,includetheSRSScombination ofLOCAandseismicloads,consistent withtherequirement ofHUREG-0484.
Porthosecombinations designseismicloadshavebeenusedandareherebyattachedforusebytheStaff.Inallcases,designseismicloadsareconsiderably higherthancalculated peakseismicloads.Qualitatively, thesmalldisplacements observedforthevesselandcorebarrelfortheworstbreakanalyzed, stronglysuggeststhattheanalysesnowinprogressofthefuel/internals andCED>fswillindicateacceptable results.Itmustalsobenotedthatsincethesubmittal oftheAugust1977reporttotheStaff,additional workhasbeenreported, tosupportPP&Lscontention thatthetypesofinstantaneous pipebreaksbeingpostulated bytheStaffareexcessively conservative.
l.0INTRODUCTION Duringapostulated lossofcoolantaccidentintheformofacircumferential piperuptureattheinletnozzleofthereactorpressurevessel,adecompression ofthereactorpressurevesseloccursoverashortperiodoftime.Decompression wavesoriginated.
atthepostulated breaktravelaroundtheinletplenumandpropa-gatedownwardalongthedowncomer annulus.Thefinitetimerequiredbythedecompression disturbances totravelaboutthevesselcausesatransient pxessuredifferential fieldtobecreatedacrossthecoresupportbarrel(CSB)andthevesselinnersurface.Thisfieldimposesatransient asymmetric loadingonthecore-support-barrel aswellasthevesselitself.Sincethepostulated pipebreakislocatedwithinthebiological shieldwall,theblowdownfluidflash-ingintothereactorcavityalsocausesatransient pressurization actingonthevessel.Thisexternalpressurization isalsoasymmetric.
Theinternalasymmetric loading(IAL)andtheexternalasymmetric loadingactinthesamedirection forbreaksoccurring inthecoldlegpiping.Forbreaksinthehotlegs,theinternalasymmetric loadis.virtually absentinthehorizontal direction, hencethetwoloadsareadditiveintheverticaldirection only.Theseloadingsaretransmitted tothereactorvesselsupportsystem.Theresultant reactionforcesatthesupportinterfaces mustbeconsidered intheevaluation oftheadequacyofthesuppoxtsystemtogetherwiththethrustloadresulting fromthebreak,otheroperating loads,andpostulated seismicloads.Theseismicloadsandnormaloperating loads,aswellastheEALhavebeenpreviously analyzedinAppendix3HoftheFinalSafetyAnalysisReport.BreaksoutsidecavitycanresultinIALimposedonthereactorpressurevesselandinternals, andinEALonthe-reactorcoolantpumpandsteamgenerators.
Forthebreaksoutsidethecavity,theadequacyoftheprimarysystemsupportsisassessedforfullbreaksatappropriate prima~systemlocations.
Thecavitybreaksaredetermining breaksfortheassess-.mentoftheadequacyofpipingattachedtotheprimarysystempiping.Thecircumferential piperuptureattheinletnozzleofthereactorpressurevesselisdetermined tobethedesignbasisbreakfortheevaluation ofthevesselsupportadequacy.
Abreakattheoutletnozzlewouldnotproduceahorizontal asymmetric pressureloadingtothevessel.Consistent withtheFinalSafetyAnalysisReport,a4.0sq.ft.coldlegguillotine breakattheinletnozzleischosenfortheanalysesofthevesselsupportadequacy.
2.0METHODOPANALYSIS2.1ReactorVesselSuortsThe.adequacyofthereactorvesselsupportsisevaluated bydetermining theloadsactingonthepximarysystemwhichresultfromapostulated breakattheinletcoldlegnozzle;theresponseoftheprimarysystemtotheapplication oftheseloads;andthereactionforcesgenerated bythis=response atthereactorvesselsupports.
Theloadsactingontheprimarysystemconsistofnormalplusseismicloads,thethrustload,externalasymmetric loads,andinternalasymmetric loads.Thelatterthreearecombinedintruetimehistoryfashion,addedtothenormalloadsreactions, thenthexesul-tantreactionloadsatthesupportsarecombinedwithdesignreactionloadsresulting fromthepostulated seismic(SSE)eventsbySRSStechniques, toobtaintheoverallreactionloadateachofthesupports.
Designseismicloadsareprovidedforeachprimarysystemsupportinthethreeorthogonal direc-.tionsinTable1.Itshouldbeemphasized thatcomputedpeakseismicloadsareingeneralsubstantially lessthanthedesignseismicloads;thusproviding anelementofconservatism inthisanalysis.
Table2givesasamplecomparison ofcalculated anddesignseismicloadsatrepresentative locations.
Thefollowing subsections describethemethodology employedtoevaluateeachofthethrust,externalasymmetric andinternalasymmetric loads.Inherentintheeyaulation oftheseloadsisthedetemination ofthetime.requiredtoopenupthebreaktotheareabeinganalyzed.
2.1.1BreakOpeningTimeandThrustLoadsTheSt.Lucieplantprimarycoolantpiping'in thevicinityofthevesselisrestrained fromunlimited motionfollowing completeseverance intheportionwithinthecavitybyrestraints intheprimaryshieldwallpenetrations andwireropesaroundthereactorcoolantpumps.Thisrestraining systemhasbeenprevious-lydescribed intheFSAR,Following anarbitrarily assumedinstantaneous severance ofthepipeatthenozzle,thetwoendsofthebrokenpipeseparateundertheactionofthethrustimposedbytheinstantaneous tensionreleasefollowedbytheblowdownoftheescap-ingfluid,andformacombinedbreakareawhichvarieswithtimeasgiveninthefollowing equation:
mR.SX(T)2.Bnmg(R.+R)t(v)=<5+2Rjm-(--s'v.2g)f-whereRiandRaretheinnerandouterpiperadii,t0isthepipethz.ckness, xistheaxialsepanation ofthetwoendswhichvarie'swithtime7,andg=cos2R.i(2)whereinyistheradialseparation ofthetwobrokenendswhichalsovarieswithtime.Thisequationissolvediniterative fashiontogetherwiththeequationforthecombinedtensionreleaseandblowdownforce,givenbelowV(T)2F(x)P(v)A+p(x)A(v)-dlpdlg(3)toyieldthecorrectforcingfunctionandbreakareaasafunctionoftime.Inequation(3),Pandpdarethepressureandfluiddensityinthe3xscharge leg,respectively, Aisthecross-sectional areaofthepipe,VthebloBdownvelocity, andA(7)isdefinedin(1)above.Themotionofthepipingsystemundertheapplication oftheforcegivenby(3),iscomputedbymodelling the'ischarge leg,thepump,andthecrossoverlegwithanel@to-plastic finiteelementcomputerprogram,PLAST-considering thesteamgenerator andthevesseltoremainmotionless.
Resultsoftheanalysesindicatethat-atleast18msec.arenecessary forthepipeendstoseparatetheoverallareaof4.0sq.ft.refermdtointheFSAR.Thisanalysisalsoindicates thatasaresultofplasticrotationatthepump,itispossibleforthepipeendstoseparatefurther,toamaximumareaof7.78sq.ft.Thetimerequiredforthisareatobeachieved, however,wouldbeinexcessof25msec.ThelongertimerequiredforopeningthelargerbreakinsuresthattheIALresult-ingfromthetwobreaksarevirtually identical.
Thelargerbreakdoeshoweverresultinalargerexternal horizontal asymmetric load(external verticalasym-metricloadsarevirtually identical forthetwobreaks).Sincethe4.0sq.ft.breakhadbeenone'fthedesignbasisbreaksintheFSAR,allanalysesusedthatbreakarea.However,consideration isgiventowhetherthesystemiscapableofaccommodat-ingthelargerbreak.Asdiscussed inthesubsequent section,thesystemisinfactadequateforthelargestofthebreaks.2.1.2ExternalAsymmetric PressureLoads(ReactorCavity)Thereactorsubcompartment analysisforSt.LucieUnit81hadbeenperfoimed forstipulated LOCAconditions including a4.0sq.ft.coldlegguillotine break,andtheresultshadbeensubmitted totheNRC.intheFSARandapprovedbytheNRCduringthecourseoftheoperating licensereview.Theresultsforthe4.0sq.ft.coldlegguillotine break,asreportedinReference 2,havebeendirectlyusedin'thepresentstudy.Thisresults.inconservatism oftheanalysissincethecavityresponsehadbeen,predicated onabreakopeningtimeof10msec,whereas18msec.isneededtoachievethissizebreak.Thepeakexternalasymmetric forcesacrossthereactorvessel,thatwouldresultfromthelarger7.78sq..ft..break,wouldbeapproximately 40percentlarger.Thisispredicated onaratioof1.39betweenpeakandaverageenergyflowtothecavityresulting froma7.78sq.ft.anda4.0sq.ft.coldlegbreakrespectively.
Intheoriginalanalysis, however,twoelementsofconservatism hadbeenintroduced.
First,themassandenergyreleaseshadbeenincreased by10percentandsecond,allinsulation hadbeenassumedtoreamininplaceinthereactorcavityandventareasforthepurposesofvolumeandventareacalculations inthemathematical model.Theinsulation intheuppercavityreacheswouldbecrushedagainstthevesseluponcavitypressurization, resulting inanincreased volumeofapproximately 15-20percent.Hence,realistic modelingoftheinsulation
: behavior, coupledwithremovalofthe10percentconservatism inthemassandenergyreleasewouldresultinapre-dictedexternalasymmetric pressureloadandcavitypressureloadfroma7.78sq.ft.breakwhichisonly15to20percenthigherthanthoseconservatively pre-dicted.
2.1.3InternalAsymmetric PressuxeLoadsThemodelusedtodetermine thepressurefieldateverypointintheprimarysystemfollowing thepostu-latedprimarysystembreaks,fromwhichtheinternalasymmetric forcesonthevesselandcoresupportbarrelarededuced,isshowninFigurel.TheRELAP-4-thexmalhydraulic codeisusedtocompute3/thethermodynamic properties inthemodelvolumesandjunctions.
ResultsoftheRELAP-4modelhavebeencomparedtoresults achieved.
bymodelling thesystemwithWHAM-6-fortheperiodoftimeduxingwhichthelattercanbeappliedwithconfidence, whichisalsotheperiodoftimeofinterest.,
Figure2showsthemodelemployedforWHAM-6.AsimilarWHAMmodelandassumptions initsuse,hadbeenp~viously submitted totheStaffintheAugust1977report.Theresultsofthetwomodelsaxeingoodagreement, withRELAP-4predicting alargerpressuredifferential acrossthecoresupportbarrel.Resultsoftheinternalasymmetric loadsanalysisindicatethatthepeakforcesacrossthecoresupportbarrelandthevesselarevirtually insensitive tothebreakarea,butextremely sensitive tobeakopeningtimes.Forinstance, achangeinaxeafrom1sq.ft.requiring 8msec.toopentoapproximately 9.81sq.ft.(complete double-ended areabreak)withanopeningtime.of36msec.,onlyresultsina2to3percentincreaseinpeakinternalasymmetxic loads,whereasadecreaseinopeningtimefrom36msec.to1msec.forthefullbreakbringsaboutathreefold increaseininternalasymmetric load.2.1.,4VesselandPrimarySystemStructural ModelAnon-linear elastictimehistorydynamicanalysisofthree-dimensional mathematical modelofthereactorcoolantsystemincluding detailsofthereactorinternals, pressurevessel,supports, andpipingwasperformed forthepostulated pipebreaktoprovidereactorvesselsupportreaction,forces.
Thestructural modelemployedisshowninFigures3(a)and3(b).Thismodelisthree-dimensional andhas981totalstaticdegreesoffxeedomand77mass.degreesoffreedom.Thereactorvesselandallinternalcomponents aremo'delled atinternalandsupportinterfaces.
TheSTRUDL-computercodegenerates thecondensed 5/stiffness matrixusedinthedynamic'analysis fromthephysicaldefinition ofthestructure.
Hydrodynamic effects,including bothvirtualmassandannulareffectsareaccounted forinthecouplingbetweentheRPVandtheCSB,andbetweentheCSBandthecoreshroud.Thehydrodyamic (added)massmatrixisevaluated usingtheADifASS-code..Thedyanmicanalysistodetermine thesystyyresponsewasperformed usingthecomputercodeDAGS-andDFORCE-.Thereactorpressurevesselsupportsystemisdescribed intheFSAR.Themodelling ofthesteelportionofthesupportisidentical tothatdescribed intheFSARinAppendix3H.Thebasicmodelofthebiological shieldwallisalsoidentical.
However,amorerefine(analysisisemployedforthelatter,utilizing aNASTRAN-nonlinear solutionprocedure employing quadrilateral andtriangular planestressconcretecrackingfiniteelements, insteadoftheSTARDYNEmethodofsolutiondescribed inAppendix3HoftheFSAR.2.2ReactorCoolantPiinConnected PinandOtherRCSSuorts2.2.1SteamGenerator SupportsOutsidethereactorcavity,breakshavebeenassumedatappropriate locations.
TheRCSsupportsmostaffectedarethelowersteamgenerator supports.
Theprimarysystemmodelisanalyzedonanelasticbasisforbothhotlegandcoldlegbreaks,thehotlegbreakatthesteamgenerator inletbeingthedetermining eventfortheSteamGenerator support.Thisanalysisisastaticanalysiswhichemploysthecompu(p)code51EC-21(HareIslandpipingflexibility code)-.BothLOCAanddes'ignseismicloadsareincludedintheanalysis.
2.2.2ECCSandOtherConnected PipingTheanalysisofthestressesgenerated intheECCSlinesandotherlinesattachedtotheprimaxyloopinvolvedatwostepprocess.First,thetimehistories ofthedis-placements aregenerated ateachnozzleattaching saidpipingtotheprimaryloop.The"worst"timehistory,irrespective ofthelocationatwhichisoccursis appliedtothelinewhichbyconfiguration andotherloading(normalandseismic)wouldresultinthehigheststresses.
ThestressesinducedbyLOCAmotionsforthisparticular configuration areadded-topreviously computednormalandseismic(SRSS)stresses.
Thedetermining breakforECCSlineevalua-tionisthecoldlegnozzlebreakinthecavity.2.2.3ReactorCoolantPipingThestructural modelfortheprimarysystemisalsoutilizedtodetermine thestressconditions intheintactportionofthereactorcoolantloop.3.0RESULTSOFTHEANALYSES3.1VesselSuortsTheloadscalculated foreachreactorvesselsupportbythemethodoutlinedinSection2.1.4arereportedinTable3forthebreakchosenfortheanalysis; i.e.,the4.0sq.ft.coldlegbreakattheinletnozzle;forarangeofreactorvesselsupportstiffnesses.
Thisrangecoversthepossiblevaluesoftheoverallstiffness oftheindividual'actor vesselsupports, therealvaluebeingsomewhere betweenthetwoextremes.
Itisnotpossibletoquantifythestiffness valuemoreprecisely sincethemodelling oftheboundarycondition representing embeddedsteelinthebiological shieldissubjecttovariation.
Inthesupportanalyseshowever,thehigherloadsresulting fromtheuseofthehigheststiffness, havebeenutilized.
Thisinsuresagainthattheabsolutemaximumloadpersupportiscomputed.
Inreality,lowervaluesareexpected.
Thecapability ofthereactorvesselsupportsisgiveninFigure4andTable4respectively fortheRPVsupportpadcapability andtheweakestlinkinthesteelsupport/biolo-gicalshieldstructure.
Sincethecapability ofthesupportsexceedthemaximumloadscomputedforthegivenbreak,itisconcluded thattheexist-ingsupportsystemisadequateforthatbreak.AsstatedinSection2.1,itispossiblethat,asaconsequence ofthebrokendischarge linerotationaboutthepump,alargerbreakareacouldformwithinthecavity,uptoamaximumof7.78sq.ft.Thislargerbreakarea,requiring aproportion-atelylongertimetoopen,hasvirtually noeffectonthrustandinternalasymmetric loads,butwouldincreasethehorizontal externalasymmetric loadbyapproximately 15-20percentoverthat usedintheanalysis, asexplained inSection2.1.2.TheEALrepresents approximately 40percentoftheoverallload.Hence,a20percentincreaseinthisloadwouldresultinlessthana10percentincreaseintheoverallloading.FromTable4andFigure4,itcanbeseenthatthisincreasewouldbeaccommodated bythemarginsexistinginthesupportsystem.Itistherefore concluded thatthereactor'essel supportscanwithstand thelargestbreakinthecoldlegpipingwithinthecavity.SincecoldlegbreaksoutsidethecavitydonotproduceEALloadsandsincethe'IALisvirtually unaffected bytheareaofthebreakasexplained inSection2.1.3,itisalsoconclu-dedthatthereactorvesselsupportsarecapableofwithstanding anyloadresulting frompostulated rupturesoutsidethecavity.Adetailedanalysisofthereactorloadsresulting fromhotlegbreakswithinthecavityhasnotbeenperformed.
Themasonsareasfollows:thestiffness ofthehotleg,pipecombinedwiththesteamgenerator restraining action,resultsinabreakareawithinthecavitywhichissmallerthanthecoldlegbreakarea,henceresulting EALwouldbelowerthancalculated forthecoldlegbreak;althoughthethrustforceinitially wouldbelarger,theIALwouldnotbecolinearwiththrustandEAL,butwouldinfactbeapproximately orthogonal tothem.Theresultant horizontal loadsonthevesselsupportstherefore, wouldclearlybesmaller.Forinstance, thereactions atreactorvesselsupports, duetoahotlegbreakhavebeencomparedtothereactions duetoacoldlegbreakforthrustandsubcompartment pressureonly.Horizontal HotLeBreak(Kis)Horizontal ColdLeBreak(Kis)ColdLegSptHotLegSpt427032703275Althoughtheloadonthecoldlegsupportismoresevereforahot.legbreakthanforacoldlegbreak,whentheeffectsofinternalasymmetric loads-are added,thecoldlegbreakwillgovern.Verticalloadswouldbeofthesame'order ofthoseexperienced asaresultofcoldlegbreaks,andthecapacityofthesupportsystemtoaccommodate verticalloadsissignificantly higherthanitshorizontal capability.
Henceclearlythereactorvesselsupportsystemisalsocapableofwithstanding theeffectsofpostulated hotlegbreaksinsideandoutsidethereactorcavity.
Asimilarconclusion hadbeen,reachedinourAugust1977report.Differences inmaximumloadsreportedhereinfromthosereportedintheAugust1977reportaretwofold.TheAugust1977reportdidnotconsiderinternalgapsorgapsbetween'he supportpadsandthesupportstructure.
TheAugust1977reportconsidered therefore thatallloadedsupportswouldbeloadedsimultaneously andsharetheloadequally.Theagreement oftheoverallloading.betweenthepresentandtheAugust1977results,confirmthattheapproachtakenin1977toassesstheloadswasnotunreasonable.
3.2OtherRCSSuortsTheonlysupportsontheprimarysystem,otherthanthevesselsupports, arethesteamgenerator supports.
Resultsoftheanalysesoftheloadsimposedonthesesupportsfrombothhotandcoldlegbreaksinthesystemincombination withseismicloads,indicated thatnoneofthedesignloadshavebeenexceed-ed,withexception oftheloadsonthefourholdownboltsatthevesselendofthesteamgenerator slidingbaseandtheslidingbaseitself.ThecomputedanddesignloadsareshowninTable5.Individual examination oftheslidingbase,thebolts,andboltanchorages howeverindicates thatallcanacceptably withstand theappliedloads.Itistherefore conclu-dedthattheexistingsupportsdesignisadeq'uate.
3.3ReactorCoolantPiinTable6reportstheelastically calculated piperupture-andseismicloadsonintactreactorcoolantpipingassociated withthebrokenloopfortheworstbreak,whichisthecoldleg.guillotine breakatthevesselsafeend.Examination ofthistablerevealsthatallloadsfallwithintheallowable loadswiththeexception oftheloadattheRCPdischarge nozzle,whichexceedtheallowable byabout,l3percent,onanelasticbasis.Sincethisanalysis~ispredicated ona4.0sq.ft.coldlegbreak,bythearguments presented inSection3.1,consideration ofthelargestbreakthatcouldoccuratthevesselsafeend;i.e.,7.78sq.ft.,requiresthatanincreaseinloadoflessthan10percentbeexaminedtoassessthea'dequacy ofthecoolantpiping.Suchanincrease'can bereadilyaccommodated attheRCPsuctionandRVoutletnozzles.TheRCPdischarge wouldbemoreoverstressed (onanelasticbasis)andtheRVinletwouldbeveryslightlyoverstressed.
Sinceonlythefluidretaining integrity ofthiscoolantpipingneedstobemaintained duringthepostulated LOCA,ananalysisconducted onanelasto-plastic basiswouldconcludethatthis integrity wouldbemaintained atthosenozzles.Sincetheamountofoverstressing calculated onanelasticbasisisrelatively small,aplasticanalysiswasnotconsidered necessary.
Duringtheperformance ofthisparticular'analysis itwascalculated thatthesnubbersonthereactorcoolantpumpsareoverstressed.
Thesesnubbe~arenotneededfortheseevents.Howevertheirfailurecouldaffecttheresults.Hence,theanalysiswasrepeatedbytakingnoaccountofthesnubbers.
ResultsarealsoreportedinTable6~Ascanbeclearlyseen,theeffectofthepresenceorabsenceofthesnubbersisnegligible.
3.4ECCSandConnected PiinThestressescomputedfromtheanalysisdescribed inSection2.2.2arewithin10percentoftheallowable, andhenceitisconcluded thattheECCSpipingandotherpipingconnected totheprimaryloop,isnotadversely affectedbythepostulated event.Table7comparesthepeakcomputedstresses, whichincludenomalandseismicloadstotheallowable stresses.
Themarginexistingbetweenpeakstressescalculated onanelasticbasisandstressesthatwouldbeallowedwithinanelasto-plastic analysisfurtherindicates thatthisattachedpipingwouldbeabletowithstand theimposedloadsfromthe7.78sq.ft.largercoldlegguillotine break.3.5SeismicLoads,PursuanttotheStaff'srequestattheJanuary16,1980meeting,Table1providesthedesignseismicloadsatthevarioussupportpointsintheReactorCoolantSystem.3.6ControlElementAssemblies AlthoughtheanalysisoftheControlElementDrivesresponsetopostulated LOCAeventsisinprogress, butwillnotbecomple-teduntilJuly1980,i'tisgermanetopointoutthattheCEAsarenotneededforbreaks'intheRCSwhichexceed0.5sq.ft.Theassumption ofacompleteguillotine willresultinbreakslargerthan0.5sq.ft.  


==4.0CONCLUSION==
==4.0CONCLUSION==
Eventhoughsomeanalyseshavenotyetbeencompleted,resultsobtainedtodatedemonstratethattheexistingdesignhassignifi-cantcapabi/jtyl)oaccommodatethepostulatedevents.Additionalinformatio~whichhasbecomeavailablesincetheAugust1977report,andwhichreinforcesourcontention,statedinthatreport,demonstratesthatsucheventsareofanacceptablylowprobabilityandcannothappeninthemannerpostulatedforthisanalysis.TheforegoingreaffirmsourconclusionthatthedesignofSt.LucieUnitlisacceptable.  
 
Eventhoughsomeanalyseshavenotyetbeencompleted, resultsobtainedtodatedemonstrate thattheexistingdesignhassignifi-cantcapabi/jtyl)o accommodate thepostulated events.Additional informatio~
whichhasbecomeavailable sincetheAugust1977report,andwhichreinforces ourcontention, statedinthatreport,demonstrates thatsucheventsareofanacceptably lowprobability andcannothappeninthemannerpostulated forthisanalysis.
Theforegoing reaffirms ourconclusion thatthedesignofSt.LucieUnitlisacceptable.  


==5.0REFERENCES==
==5.0REFERENCES==
-"PLAST-AnElasto-PlasticComputerProgramforStressAnalysisof3-DPipingSystemsandComponentsSubjecttoDynamicForces",submittedtotheNRCasETR-1001-EbascoTopicalReport.-St.LucieUnitNo.1FSAR,DocketNo.50-335,Amendment44.*2/-"RELAP4-AComputerProgramforTransientThermalHydraulicAnalysis3/ofNuclearReactorsandRelated,Systems",User'sManual,ANCR-NUREG-1335.-Fabic,S.,ComputexProgramWHAMforCalculatingPressure,Velocity4/andForceTransientsinLiquidFilledPipingNetwork",KaiserEngineeringReportNo.67-49-R,November1967.-"ICESSTRUDLII-TheStructuralDesignLanguageEngineersUser'sManual",MITPress,Cambridge,Massachusetts,1968.-"ADMASS-AComputerCodeforFluidStructureInteractionUsingtheFinite6/ElementTechnique",EbascoServices,Incorporated,1979.-"DAGS-CENPD168,Revision1-DesignBasisPipeBreaks",September1976.-"DFORCE-DesignBasisPipeBreaks",September1976.-"MSC/NASTRAN-User'sManual",McNealSchwandlerCorporation,LosAngeles,California.-"WCAP9570Class3-MechanisticFractureEvaluationofReactorCoolant10/PipeContainingaPostulatedCircumferentialThruWallCrack",byPalusamy,S.S.,andA.J.Hartmann,October1979.-Ayers,D.J.andT.J.Griesbach,'-'OpeningandE~tensionofCircumferentialCracksinaPipeSubjectedtoDynamicLoads",FifthInternationalConferenceofStructuralMechanicsinReactorTechnology,Berlin,Germany,1979.-Griffin,J.H.,"MEC-21-APipingFlexibilityAnalysisProgram",TID-4500(31stedition),LA-2924,UC-38,July14,1964.
 
TABLE1ST.LUCIE1NORMALANDSEISMICSUPPORTLOADS(X106LB.)CONDITIONLOADH1V1NV10.GGG4195.0281.155i.360IIOAMALOPEIIATINGTHEGMAL+DEADDEADVIEIGHTV(EIGHT.005.032ODESEISMICSY.002.335-.G44-.04G.011.064DBESEISSIICSY.005.6701.288-.092IfNAV1V$tVHZV2NV2.G64a.195-.091.72Gk.2151.226.017.001.253+.355-.264-.3802.452035.003.507+.710-.528.761ivtI$$ACIOIIV$$$($$Vt(OIIIA(ACIIO(NV3NV3Z11Z12Y1Y2Y3Y4xNYx.19500.300.3001.3001.3000a.376.741%.215.367000.3151.009.3200S.30000.016-.057.086-.0540.0791.139-.019-.060.G2300-.019.155.417.1520.270-.349.743S.19541970.060-.07105802.278-.00600.033-.1'14.173-.1080-.038~120.50G00-.039211.835.3050.540.6SS.746S.390S.3940.121.143.1160Y$$($YI.vhVf$(fANC(N(AAIONLOW(N$V(YOA1$YI($($N Table2ComparisonofPeakCalculatedandDesignSeismic(DBE)LoadsatRepresentativeLocationsDesign(Kips)HorizontalVerticalCalculated(Kips)HorizontalVerticalColdLegSptHotLegSptl,2937622,455.1,268522.6515.0354.6429.4 Table3St.LucieUnitfi'1RVSUPPORTIfAXABSREACTIONS(KIPS)-LOCA+SEISMIC(SRSS)4FTCLGBREAKATNOZZLElAOR2ALOCATIONS8'1ASPPTRVSPPTSTIFFNESSVALUESK='4.62x10lb/in6K~59.71x10lb/in6K=77.54x10lb/in6-K=75.83x10lb/in6VerticalHorizontal1397150223171587ulBSPPTVerticalHorizontal2800533122515473-HotLegSPPTVerticalHorizontal3458749330487777ForLOCA+Nopreactions,addthesevaluestotheverticalresults:~21ASPPT710~K81BSPPT726.KHotLegSPPT1157K+Forbreakatnozzle1Bor2B,theloadsonthecoldlegsupportswouldbereversed Table4St,Lucie1ReactorPressureVesselSupportCapacitySteelsupportstructure-horizontal8400kips*(concreteislimiting)Steelsupportstructure-verticaldownward12000kipsReactorCavityWallReactorCavityWallReactorSupportPadsReactorSupportPadshorizontalverticalhorizontalvertical".13000kips*~notlimitingSeeFigure4SeeFigure4Loadonindividualgirder*<Allowableresultantasymmetricmechanicalloadtransmittedalonggirderstoconcrete,basedonrebarmeanaxialstress'beingwithinyield.
-"PLAST-AnElasto-Plastic ComputerProgramforStressAnalysisof3-DPipingSystemsandComponents SubjecttoDynamicForces",submitted totheNRCasETR-1001-EbascoTopicalReport.-St.LucieUnitNo.1FSAR,DocketNo.50-335,Amendment 44.*2/-"RELAP4-AComputerProgramforTransient ThermalHydraulic Analysis3/ofNuclearReactorsandRelated,Systems",
TABLE5STEAMGENERATORLOWERSUPPORTCALCULATEDANDDESIGNLOADSIREFERTOTABLE1FORSYMBOLS)SUPPORTZ11Z12FRONTY1SIDEY2BACKY3SIDEY4X-STOPZ1Z2CLGUILLNO.1+DBEIRSS)727806-406.9-756.5-605.0-300.178194301HLGUILLNO.2+DBEIRSS)42-2487.7-1176.4+1249.0-1175.9-5194.92784040DESIGNLOADLOCA+DBE3,600-1,868"-1,770-1I737-,691-1,7345,648,301-1,5741,800IKANDFT-KIPS)9gSTEAMGENERATOR/SLIDINGBASESUPPORTSKIRTINTERFACE.FxFyFz'xMzIHLGUILL)LOCA5205-3582M609RSSLOCA5DBE5205-35826.8418.34614SLIDINGBASEDESIGNLOADS5653-2,471.011.032.024.01003"ANEGATIVESIGNMEANSTENSION Table6St.LucieUnitIIlReactorCoolantSystemReactorPressureVesselandReactorCoolantPumpNozzleLoadsDuetoa4ftReactorVessel1AInletNozzle-GuillotineBreakPIPERUPTURERSSMOMENT(In-Kis)NozzleRCPDischargeRCPSuctionRVInletRVOutletRCPSnubber109,30050,50071,75050,150RCPSnubberNotAc~tin109,60054,55071,91050,170SeismicMoment(In-Kis)5,9107,2565,2722,535AllowableMoment(In-Kis)96,81078,96578,965279,340 Table7St.LucieUnitNo.1ConnectedPipingStressesCalculatedvs.Allowable4.0sq.ft.CLGInletBreakDesignPoint(RefertoFiure5)CalculatedStress(Eu.10ASME)AllowableStress3X5639,07075,152*75,030*41,83543,47547,69033,43020,17148,60048,60048,60048,60048,60048,60048,60048,600FunctionabilityandintegrityareassuredifLevelB(upsetconditions)limitsoftheASMEBoilerandPressureVesselCode,SectionIII,Division1arenotexceeded.Functionabilityisimportantatpoints5and6wherethevalveis.Atpoints2and3,theselimitsareexceeded.However,LevelD(faultedlimits)arenotexceededatthesetwopoints.LevelDlimitsareusedtodemonstratethatintegrityismaintained.Equation(9)atthosetwopointswouldyield45,043psi.and44,479psirespectivelywithanallowableof48,600psi.
User'sManual,ANCR-NUREG-1335.
-Fabic,S.,ComputexProgramWHAMforCalculating
: Pressure, Velocity4/andForceTransients inLiquidFilledPipingNetwork",
KaiserEngineering ReportNo.67-49-R,November1967.-"ICESSTRUDLII-TheStructural DesignLanguageEngineers User'sManual",MITPress,Cambridge, Massachusetts, 1968.-"ADMASS-AComputerCodeforFluidStructure Interaction UsingtheFinite6/ElementTechnique",
EbascoServices, Incorporated, 1979.-"DAGS-CENPD168,Revision1-DesignBasisPipeBreaks",September 1976.-"DFORCE-DesignBasisPipeBreaks",September 1976.-"MSC/NASTRAN
-User'sManual",McNealSchwandler Corporation, LosAngeles,California.
-"WCAP9570Class3-Mechanistic FractureEvaluation ofReactorCoolant10/PipeContaining aPostulated Circumferential ThruWallCrack",byPalusamy, S.S.,andA.J.Hartmann, October1979.-Ayers,D.J.andT.J.Griesbach,
'-'Opening andE~tension ofCircumferential CracksinaPipeSubjected toDynamicLoads",FifthInternational Conference ofStructural Mechanics inReactorTechnology, Berlin,Germany,1979.-Griffin,J.H.,"MEC-21-APipingFlexibility AnalysisProgram",
TID-4500(31stedition),
LA-2924,UC-38,July14,1964.
TABLE1ST.LUCIE1NORMALANDSEISMICSUPPORTLOADS(X106LB.)
CONDITION LOADH1V1NV10.GGG4195.0281.155i.360IIOAMALOPEIIATING THEGMAL+DEADDEADVIEIGHTV(EIGHT.005.032ODESEISMICSY.002.335-.G44-.04G.011.064DBESEISSIICSY.005.6701.288-.092IfNAV1V$tVHZV2NV2.G64a.195-.091.72Gk.2151.226.017.001.253+.355-.264-.3802.452035.003.507+.710-.528.761ivtI$$ACIOIIV$$$($$Vt(OIIIA(ACIIO(N V3NV3Z11Z12Y1Y2Y3Y4xNYx.19500.300.3001.3001.3000a.376.741%.215.367000.3151.009.3200S.30000.016-.057.086-.0540.0791.139-.019-.060.G2300-.019.155.417.1520.270-.349.743S.19541970.060-.07105802.278-.00600.033-.1'14.173-.1080-.038~120.50G00-.039211.835.3050.540.6SS.746S.390S.3940.121.143.1160Y$$($YI.vhVf$(fANC(N(AAION LOW(N$V(YOA1$YI($($N Table2Comparison ofPeakCalculated andDesignSeismic(DBE)LoadsatRepresentative Locations Design(Kips)Horizontal VerticalCalculated (Kips)Horizontal VerticalColdLegSptHotLegSptl,2937622,455.1,268522.6515.0354.6429.4 Table3St.LucieUnitfi'1RVSUPPORTIfAXABSREACTIONS (KIPS)-LOCA+SEISMIC(SRSS)4FTCLGBREAKATNOZZLElAOR2ALOCATIONS 8'1ASPPTRVSPPTSTIFFNESS VALUESK='4.62x10lb/in6K~59.71x10lb/in6K=77.54x10lb/in6-K=75.83x10lb/in6VerticalHorizontal 1397150223171587ulBSPPTVerticalHorizontal 2800533122515473-HotLegSPPTVerticalHorizontal 3458749330487777ForLOCA+Nopreactions, addthesevaluestotheverticalresults:~21ASPPT710~K81BSPPT726.KHotLegSPPT1157K+Forbreakatnozzle1Bor2B,theloadsonthecoldlegsupportswouldbereversed Table4St,Lucie1ReactorPressureVesselSupportCapacitySteelsupportstructure
-horizontal 8400kips*(concrete islimiting)
Steelsupportstructure
-verticaldownward12000kipsReactorCavityWallReactorCavityWallReactorSupportPadsReactorSupportPadshorizontal verticalhorizontal vertical".13000kips*~notlimitingSeeFigure4SeeFigure4Loadonindividual girder*<Allowable resultant asymmetric mechanical loadtransmitted alonggirderstoconcrete, basedonrebarmeanaxialstress'being withinyield.
TABLE5STEAMGENERATOR LOWERSUPPORTCALCULATEDANDDESIGNLOADSIREFERTOTABLE1FORSYMBOLS)SUPPORTZ11Z12FRONTY1SIDEY2BACKY3SIDEY4X-STOPZ1Z2CLGUILLNO.1+DBEIRSS)727806-406.9-756.5-605.0-300.178194301HLGUILLNO.2+DBEIRSS)42-2487.7-1176.4+1249.0-1175.9-5194.92784040DESIGNLOADLOCA+DBE3,600-1,868"-1,770-1I737-,691-1,7345,648,301-1,5741,800IKANDFT-KIPS)9gSTEAMGENERATOR/
SLIDINGBASESUPPORTSKIRTINTERFACE
.FxFyFz'xMzIHLGUILL)LOCA5205-3582M609RSSLOCA5DBE5205-35826.8418.34614SLIDINGBASEDESIGNLOADS5653-2,471.011.032.024.01003"ANEGATIVESIGNMEANSTENSION Table6St.LucieUnitIIlReactorCoolantSystemReactorPressureVesselandReactorCoolantPumpNozzleLoadsDuetoa4ftReactorVessel1AInletNozzle-Guillotine BreakPIPERUPTURERSSMOMENT(In-Kis)NozzleRCPDischarge RCPSuctionRVInletRVOutletRCPSnubber109,30050,50071,75050,150RCPSnubberNotAc~tin109,60054,55071,91050,170SeismicMoment(In-Kis)5,9107,2565,2722,535Allowable Moment(In-Kis)96,81078,96578,965279,340 Table7St.LucieUnitNo.1Connected PipingStressesCalculated vs.Allowable 4.0sq.ft.CLGInletBreakDesignPoint(RefertoFiure5)Calculated Stress(Eu.10ASME)Allowable Stress3X5639,07075,152*75,030*41,83543,47547,69033,43020,17148,60048,60048,60048,60048,60048,60048,60048,600Functionability andintegrity areassuredifLevelB(upsetconditions) limitsoftheASMEBoilerandPressureVesselCode,SectionIII,Division1arenotexceeded.
Functionability isimportant atpoints5and6wherethevalveis.Atpoints2and3,theselimitsareexceeded.
However,LevelD(faultedlimits)arenotexceededatthesetwopoints.LevelDlimitsareusedtodemonstrate thatintegrity ismaintained.
Equation(9)atthosetwopointswouldyield45,043psi.and44,479psirespectively withanallowable of48,600psi.
FIGURE1RELAP4510DELFORST.LUCIEPR)MARYCOOLANTSYSTEM3')3256004591160305731$131458839615168123377462634862eoo91063951123241Z1314153116175419204$414245462122255123472448QS3,265973500>>378551767S4948476152(A1)8081536335(81)717043424140Q6955S6S7Qoo'(a2)98VAt.VB74734645(82)Q72 FIGURE2ST.LUCIE1RCS-V/HAM/6MODELFORIALpssQssQss107741060721087110410310111312102811482020187538658eo8583~84891091107069>>5757677g1148P8178821Q117018192013'4261828270,0,0,800477946Qs20101681512191631495157956261962'00996766242598Qss003542224303844,7746230~3932Qss3340(A1)(81)41Qss4552oo5358604269614I76075747338041554962=56P1P14P10~~Xo>>904072120697167118~83070Pso211220~BRGAKP5(A2)P18(82)
FIGURE1RELAP4510DELFORST.LUCIEPR)MARYCOOLANTSYSTEM3')3256004591160305731$131458839615168123377462634862eoo91063951123241Z1314153116175419204$414245462122255123472448QS3,265973500>>378551767S4948476152(A1)8081536335(81)717043424140Q6955S6S7Qoo'(a2)98VAt.VB74734645(82)Q72 FIGURE2ST.LUCIE1RCS-V/HAM/6MODELFORIALpssQssQss107741060721087110410310111312102811482020187538658eo8583~84891091107069>>5757677g1148P8178821Q117018192013'4261828270,0,0,800477946Qs20101681512191631495157956261962'00996766242598Qss003542224303844,7746230~3932Qss3340(A1)(81)41Qss4552oo5358604269614I76075747338041554962=56P1P14P10~~Xo>>904072120697167118~83070Pso211220~BRGAKP5(A2)P18(82)
FIGUPESAST.LUCIE1REDUCEDMODELOFREACTORINTERPeALSUGS38'A18:AZ'2.16HX-DIRIS//TOOUTLETNOZZLES'"28I10'926'4,',22',FUEL'CORESHROUD.CSB20,A13HLEGENDA~AXIALGAPH=HORIZONTALGAP//=PRELOADEDCOUPLING=GAPCOUPLING=COLINEARCONNECTOR'SEEFIGURE3bFORDETAILSOFREACTORVESSELSANDPIPING v1'FIGURE38STLUCIE1REDUCEDMODELOFREACTORCOOLANTSYSTEMTOS.G.NO.1'rrro99189999REACTORVESSELHOTLEGTOS.G.NO.29909INTERNALS'SEEFIGURE3aFORDETAILSOFINTERNALS)9905rr~ro9914o9913oLUMPEDMASS0POINTOFAPPLIEDFORCE  
FIGUPESAST.LUCIE1REDUCEDMODELOFREACTORINTERPeALS UGS38'A18:AZ'2.16HX-DIRIS//TOOUTLETNOZZLES'"
.FIGURE4ST.LUCIE1.-:REACTORPRESSUREVESSELSUPPORTPADCAPABILITYIhC'K-10HOTLEGSUPPORT,='4.0SO.FT.CLG'COMPUTEDMAXLOADSi(LOCA+SEISMIC+Mop)IQA(HOTLEGSUPPORTQB!VNBROl<ENCOLDLEGSUPPORTBROI<ENCOLDLEGSUPPORTQA~l'0Z'I0'40:~ICOLDLEGSUPPORTSp.1;2.3'.4:5I6:7.,8,9,10..1112;13:14,15,-16Rqx10(K)VERTICALLOAD.
28I10'926'4,',22',FUEL'CORESHROUD.CSB20,A13HLEGENDA~AXIALGAPH=HORIZONTAL GAP//=PRELOADED COUPLING=GAPCOUPLING=COLINEARCONNECTOR
FIXED"-~45,''-37x3536DISPLACEMENTSSPECIFIED302942432883027274510314511'l2FlGURE5':24-FIXEDSAFETYINJECTlQNLINE1-8-1(PREVIOUS972)FLGRIDAPORFB8LIGHTOOMPANYSTLUCIENO.113141517~O2120182322t  
'SEEFIGURE3bFORDETAILSOFREACTORVESSELSANDPIPING v1'FIGURE38STLUCIE1REDUCEDMODELOFREACTORCOOLANTSYSTEMTOS.G.NO.1'rrro99189999REACTORVESSELHOTLEGTOS.G.NO.29909INTERNALS
'SEEFIGURE3aFORDETAILSOFINTERNALS) 9905rr~ro9914o9913oLUMPEDMASS0POINTOFAPPLIEDFORCE  
.FIGURE4ST.LUCIE1.-:REACTORPRESSUREVESSELSUPPORTPADCAPABILITY IhC'K-10HOTLEGSUPPORT,='4.0SO.FT.CLG'COMPUTED MAXLOADSi(LOCA+SEISMIC+Mop)IQA(HOTLEGSUPPORTQB!VNBROl<EN COLDLEGSUPPORTBROI<ENCOLDLEGSUPPORTQA~l'0Z'I0'40:~ICOLDLEGSUPPORTSp.1;2.3'.4:5I6:7.,8,9,10..1112;13:14,15,-16 Rqx10(K)VERTICALLOAD.
FIXED"-~45,''-37x3536DISPLACEMENTS SPECIFIED 302942432883027274510314511'l2FlGURE5':24-FIXEDSAFETYINJECTlQNLINE1-8-1(PREVIOUS 972)FLGRIDAPORFB8LIGHTOOMPANYSTLUCIENO.113141517~O2120182322t  
'<'s~I}}
'<'s~I}}

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RCS Asymmetric LOCA Evaluation.
ML17207A876
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REACTORCOOLANTSYSTEMASYMMETRIC LOCALOADEVALUATION ST.LUCIEUNIT1-DOCKETNO.50-335)farch3,1980 SUI&fARY, InMay1975theNRCStaffwasinformedbyapressurized waterreactorlicenseethatloadsresulting fromahypothetical ruptureofthereactorcoolantcoldlegpipeintheimmediate vicinityofthereactorpressurevessel(RPV)mayhavebeenunderestimated.

InNovember1975theStaffagreedthattheseloadsshouldbeconsidered andevaluated on,agenericbasis.IFloridaPower&Light'sresponsetotheStaff'sletterofNovember26,1975indicated thatthesupportsystemdesignincorporated thereactionforcesassociated withthelargearbitrary reactorcoolantpiperuptures, andthatfurther,ithadbeenshowntoacceptably accommodate theadditional loadsassociated withdifferential pxessures withinthereactorcavityas,showninAppendix3HoftheFinalSafetyAnalysisReport.TheStaffrequested thatfurtherinternalasymmetric load(IAL)evaluations beconducted.

FP&LsletterofFebruary9,1976documents theCompany's commitments toevaluatethereactorvesselsupportcapability forthelimit-ingbreak,acommitment whichisrestatedinSupplement 2totheUnit1SafetyEvaluation Report(SER),datedHarch1,1976.InSeptember 1977FP&Ltransmitted totheNRCareportassessing themarginindesignofthevesselsupportswhentheinternalasymmetric loadsareaddedtoallpreviousloads.Thereportconcluded thatthesupportswouldadequately withstand alltheloadings.

However,sincetheanalysisdidnotaccountforgapsbetweenthevesselandthecorebarrel,andalsothevesselandthesupportstructures, ananalysiswasinitiated atthesametimetoaccountfortheseeffects.TheStaff'sletterofFebruary16,1978requested thattheevaulations conducted todatebeexpandedinscopetoincludeanassessment ofthereactorpressurevessel,fuelassemblies andinternals, controlelementassemblies, primarycoolantpipingandattachedECCSpiping,allprimarysystemsupports, andthebiological andsecondary shieldwallsforaspectrumofbreaksintheprimarysystem.FP&LsMarch1978responsestatedthatitsAugust1977reportwasfullyresponsive totheStaff'sSERrequirement, thattheSt.Lucie1designwasacceptable andthatthelargeinstantaneous pipebreaksbeingpostulated weieoverlyconservative.

TheresponsewentontosaythatFP&Lwouldpursueadditional analysesoncetheStaffapprovedtheanalytical methodsusedintheAugust1977report.Thisreplynotwith-standing, FP&Lbeingsympathetic withtheStaff'sdesiretoassessanypotential risktopublichealthandsafetyfrompostulated events,expandedtheanalysisreferredtoabove,toalsoassesstheadditional itemsidentified bytheStaff.

Thisreportdiscusses theresultsofthisexpandedanalysis.

Thecombina-tionofthrust,external, andinternalasymmetric loadsresulting fromtheinletpipecircumferential breakpresentthelargestloadtothevesselsupportsamongthosethatwouldensuefromanyofthedesignbasisbreakslistedinAppendix3EIofthePSAR.Theresultsconfirmthatthevesselsupportswilladequately withstand alltheloadsresulting fromthepostulated circumferential breakinthevesselinletpipe.Thecoldlegguillotine breakinthecavityisthebeakwhichresultsinthelargestloadingofthevesselsupports.

There-forethevesselsupportsareclearlyadequateforallotherbreaklocations.

Thisreaffirms theconclusions oftheAugust1977report.Resultsalsoshowthatallsupportsfortheprimarysystemareadequateforallbreaklocations, thatthestressesintheintactprimarypipingaridattachedlinesaresufficiently lowtoensureperformance ofintendedfunc-tions,andthatthebiological shieldwallperformsitsintendedfunction.

Thesecondary shieldwallisdesignedforpostulated primarysystemruptureswithinthesteamgenerator subcompartments.

Theanalysesoftheadequacyoffuelassemblies internals, andcontrolelementassemblies isinprogress.

ResultsareexpectedinJulyof1980.TheStaff,atameetinginJanuary1980,furtherrequested thatseismicloadsbeseparately identified.

Allresultspresented herein,aswellastheAugust1977xeport,includetheSRSScombination ofLOCAandseismicloads,consistent withtherequirement ofHUREG-0484.

Porthosecombinations designseismicloadshavebeenusedandareherebyattachedforusebytheStaff.Inallcases,designseismicloadsareconsiderably higherthancalculated peakseismicloads.Qualitatively, thesmalldisplacements observedforthevesselandcorebarrelfortheworstbreakanalyzed, stronglysuggeststhattheanalysesnowinprogressofthefuel/internals andCED>fswillindicateacceptable results.Itmustalsobenotedthatsincethesubmittal oftheAugust1977reporttotheStaff,additional workhasbeenreported, tosupportPP&Lscontention thatthetypesofinstantaneous pipebreaksbeingpostulated bytheStaffareexcessively conservative.

l.0INTRODUCTION Duringapostulated lossofcoolantaccidentintheformofacircumferential piperuptureattheinletnozzleofthereactorpressurevessel,adecompression ofthereactorpressurevesseloccursoverashortperiodoftime.Decompression wavesoriginated.

atthepostulated breaktravelaroundtheinletplenumandpropa-gatedownwardalongthedowncomer annulus.Thefinitetimerequiredbythedecompression disturbances totravelaboutthevesselcausesatransient pxessuredifferential fieldtobecreatedacrossthecoresupportbarrel(CSB)andthevesselinnersurface.Thisfieldimposesatransient asymmetric loadingonthecore-support-barrel aswellasthevesselitself.Sincethepostulated pipebreakislocatedwithinthebiological shieldwall,theblowdownfluidflash-ingintothereactorcavityalsocausesatransient pressurization actingonthevessel.Thisexternalpressurization isalsoasymmetric.

Theinternalasymmetric loading(IAL)andtheexternalasymmetric loadingactinthesamedirection forbreaksoccurring inthecoldlegpiping.Forbreaksinthehotlegs,theinternalasymmetric loadis.virtually absentinthehorizontal direction, hencethetwoloadsareadditiveintheverticaldirection only.Theseloadingsaretransmitted tothereactorvesselsupportsystem.Theresultant reactionforcesatthesupportinterfaces mustbeconsidered intheevaluation oftheadequacyofthesuppoxtsystemtogetherwiththethrustloadresulting fromthebreak,otheroperating loads,andpostulated seismicloads.Theseismicloadsandnormaloperating loads,aswellastheEALhavebeenpreviously analyzedinAppendix3HoftheFinalSafetyAnalysisReport.BreaksoutsidecavitycanresultinIALimposedonthereactorpressurevesselandinternals, andinEALonthe-reactorcoolantpumpandsteamgenerators.

Forthebreaksoutsidethecavity,theadequacyoftheprimarysystemsupportsisassessedforfullbreaksatappropriate prima~systemlocations.

Thecavitybreaksaredetermining breaksfortheassess-.mentoftheadequacyofpipingattachedtotheprimarysystempiping.Thecircumferential piperuptureattheinletnozzleofthereactorpressurevesselisdetermined tobethedesignbasisbreakfortheevaluation ofthevesselsupportadequacy.

Abreakattheoutletnozzlewouldnotproduceahorizontal asymmetric pressureloadingtothevessel.Consistent withtheFinalSafetyAnalysisReport,a4.0sq.ft.coldlegguillotine breakattheinletnozzleischosenfortheanalysesofthevesselsupportadequacy.

2.0METHODOPANALYSIS2.1ReactorVesselSuortsThe.adequacyofthereactorvesselsupportsisevaluated bydetermining theloadsactingonthepximarysystemwhichresultfromapostulated breakattheinletcoldlegnozzle;theresponseoftheprimarysystemtotheapplication oftheseloads;andthereactionforcesgenerated bythis=response atthereactorvesselsupports.

Theloadsactingontheprimarysystemconsistofnormalplusseismicloads,thethrustload,externalasymmetric loads,andinternalasymmetric loads.Thelatterthreearecombinedintruetimehistoryfashion,addedtothenormalloadsreactions, thenthexesul-tantreactionloadsatthesupportsarecombinedwithdesignreactionloadsresulting fromthepostulated seismic(SSE)eventsbySRSStechniques, toobtaintheoverallreactionloadateachofthesupports.

Designseismicloadsareprovidedforeachprimarysystemsupportinthethreeorthogonal direc-.tionsinTable1.Itshouldbeemphasized thatcomputedpeakseismicloadsareingeneralsubstantially lessthanthedesignseismicloads;thusproviding anelementofconservatism inthisanalysis.

Table2givesasamplecomparison ofcalculated anddesignseismicloadsatrepresentative locations.

Thefollowing subsections describethemethodology employedtoevaluateeachofthethrust,externalasymmetric andinternalasymmetric loads.Inherentintheeyaulation oftheseloadsisthedetemination ofthetime.requiredtoopenupthebreaktotheareabeinganalyzed.

2.1.1BreakOpeningTimeandThrustLoadsTheSt.Lucieplantprimarycoolantpiping'in thevicinityofthevesselisrestrained fromunlimited motionfollowing completeseverance intheportionwithinthecavitybyrestraints intheprimaryshieldwallpenetrations andwireropesaroundthereactorcoolantpumps.Thisrestraining systemhasbeenprevious-lydescribed intheFSAR,Following anarbitrarily assumedinstantaneous severance ofthepipeatthenozzle,thetwoendsofthebrokenpipeseparateundertheactionofthethrustimposedbytheinstantaneous tensionreleasefollowedbytheblowdownoftheescap-ingfluid,andformacombinedbreakareawhichvarieswithtimeasgiveninthefollowing equation:

mR.SX(T)2.Bnmg(R.+R)t(v)=<5+2Rjm-(--s'v.2g)f-whereRiandRaretheinnerandouterpiperadii,t0isthepipethz.ckness, xistheaxialsepanation ofthetwoendswhichvarie'swithtime7,andg=cos2R.i(2)whereinyistheradialseparation ofthetwobrokenendswhichalsovarieswithtime.Thisequationissolvediniterative fashiontogetherwiththeequationforthecombinedtensionreleaseandblowdownforce,givenbelowV(T)2F(x)P(v)A+p(x)A(v)-dlpdlg(3)toyieldthecorrectforcingfunctionandbreakareaasafunctionoftime.Inequation(3),Pandpdarethepressureandfluiddensityinthe3xscharge leg,respectively, Aisthecross-sectional areaofthepipe,VthebloBdownvelocity, andA(7)isdefinedin(1)above.Themotionofthepipingsystemundertheapplication oftheforcegivenby(3),iscomputedbymodelling the'ischarge leg,thepump,andthecrossoverlegwithanel@to-plastic finiteelementcomputerprogram,PLAST-considering thesteamgenerator andthevesseltoremainmotionless.

Resultsoftheanalysesindicatethat-atleast18msec.arenecessary forthepipeendstoseparatetheoverallareaof4.0sq.ft.refermdtointheFSAR.Thisanalysisalsoindicates thatasaresultofplasticrotationatthepump,itispossibleforthepipeendstoseparatefurther,toamaximumareaof7.78sq.ft.Thetimerequiredforthisareatobeachieved, however,wouldbeinexcessof25msec.ThelongertimerequiredforopeningthelargerbreakinsuresthattheIALresult-ingfromthetwobreaksarevirtually identical.

Thelargerbreakdoeshoweverresultinalargerexternal horizontal asymmetric load(external verticalasym-metricloadsarevirtually identical forthetwobreaks).Sincethe4.0sq.ft.breakhadbeenone'fthedesignbasisbreaksintheFSAR,allanalysesusedthatbreakarea.However,consideration isgiventowhetherthesystemiscapableofaccommodat-ingthelargerbreak.Asdiscussed inthesubsequent section,thesystemisinfactadequateforthelargestofthebreaks.2.1.2ExternalAsymmetric PressureLoads(ReactorCavity)Thereactorsubcompartment analysisforSt.LucieUnit81hadbeenperfoimed forstipulated LOCAconditions including a4.0sq.ft.coldlegguillotine break,andtheresultshadbeensubmitted totheNRC.intheFSARandapprovedbytheNRCduringthecourseoftheoperating licensereview.Theresultsforthe4.0sq.ft.coldlegguillotine break,asreportedinReference 2,havebeendirectlyusedin'thepresentstudy.Thisresults.inconservatism oftheanalysissincethecavityresponsehadbeen,predicated onabreakopeningtimeof10msec,whereas18msec.isneededtoachievethissizebreak.Thepeakexternalasymmetric forcesacrossthereactorvessel,thatwouldresultfromthelarger7.78sq..ft..break,wouldbeapproximately 40percentlarger.Thisispredicated onaratioof1.39betweenpeakandaverageenergyflowtothecavityresulting froma7.78sq.ft.anda4.0sq.ft.coldlegbreakrespectively.

Intheoriginalanalysis, however,twoelementsofconservatism hadbeenintroduced.

First,themassandenergyreleaseshadbeenincreased by10percentandsecond,allinsulation hadbeenassumedtoreamininplaceinthereactorcavityandventareasforthepurposesofvolumeandventareacalculations inthemathematical model.Theinsulation intheuppercavityreacheswouldbecrushedagainstthevesseluponcavitypressurization, resulting inanincreased volumeofapproximately 15-20percent.Hence,realistic modelingoftheinsulation

behavior, coupledwithremovalofthe10percentconservatism inthemassandenergyreleasewouldresultinapre-dictedexternalasymmetric pressureloadandcavitypressureloadfroma7.78sq.ft.breakwhichisonly15to20percenthigherthanthoseconservatively pre-dicted.

2.1.3InternalAsymmetric PressuxeLoadsThemodelusedtodetermine thepressurefieldateverypointintheprimarysystemfollowing thepostu-latedprimarysystembreaks,fromwhichtheinternalasymmetric forcesonthevesselandcoresupportbarrelarededuced,isshowninFigurel.TheRELAP-4-thexmalhydraulic codeisusedtocompute3/thethermodynamic properties inthemodelvolumesandjunctions.

ResultsoftheRELAP-4modelhavebeencomparedtoresults achieved.

bymodelling thesystemwithWHAM-6-fortheperiodoftimeduxingwhichthelattercanbeappliedwithconfidence, whichisalsotheperiodoftimeofinterest.,

Figure2showsthemodelemployedforWHAM-6.AsimilarWHAMmodelandassumptions initsuse,hadbeenp~viously submitted totheStaffintheAugust1977report.Theresultsofthetwomodelsaxeingoodagreement, withRELAP-4predicting alargerpressuredifferential acrossthecoresupportbarrel.Resultsoftheinternalasymmetric loadsanalysisindicatethatthepeakforcesacrossthecoresupportbarrelandthevesselarevirtually insensitive tothebreakarea,butextremely sensitive tobeakopeningtimes.Forinstance, achangeinaxeafrom1sq.ft.requiring 8msec.toopentoapproximately 9.81sq.ft.(complete double-ended areabreak)withanopeningtime.of36msec.,onlyresultsina2to3percentincreaseinpeakinternalasymmetxic loads,whereasadecreaseinopeningtimefrom36msec.to1msec.forthefullbreakbringsaboutathreefold increaseininternalasymmetric load.2.1.,4VesselandPrimarySystemStructural ModelAnon-linear elastictimehistorydynamicanalysisofthree-dimensional mathematical modelofthereactorcoolantsystemincluding detailsofthereactorinternals, pressurevessel,supports, andpipingwasperformed forthepostulated pipebreaktoprovidereactorvesselsupportreaction,forces.

Thestructural modelemployedisshowninFigures3(a)and3(b).Thismodelisthree-dimensional andhas981totalstaticdegreesoffxeedomand77mass.degreesoffreedom.Thereactorvesselandallinternalcomponents aremo'delled atinternalandsupportinterfaces.

TheSTRUDL-computercodegenerates thecondensed 5/stiffness matrixusedinthedynamic'analysis fromthephysicaldefinition ofthestructure.

Hydrodynamic effects,including bothvirtualmassandannulareffectsareaccounted forinthecouplingbetweentheRPVandtheCSB,andbetweentheCSBandthecoreshroud.Thehydrodyamic (added)massmatrixisevaluated usingtheADifASS-code..Thedyanmicanalysistodetermine thesystyyresponsewasperformed usingthecomputercodeDAGS-andDFORCE-.Thereactorpressurevesselsupportsystemisdescribed intheFSAR.Themodelling ofthesteelportionofthesupportisidentical tothatdescribed intheFSARinAppendix3H.Thebasicmodelofthebiological shieldwallisalsoidentical.

However,amorerefine(analysisisemployedforthelatter,utilizing aNASTRAN-nonlinear solutionprocedure employing quadrilateral andtriangular planestressconcretecrackingfiniteelements, insteadoftheSTARDYNEmethodofsolutiondescribed inAppendix3HoftheFSAR.2.2ReactorCoolantPiinConnected PinandOtherRCSSuorts2.2.1SteamGenerator SupportsOutsidethereactorcavity,breakshavebeenassumedatappropriate locations.

TheRCSsupportsmostaffectedarethelowersteamgenerator supports.

Theprimarysystemmodelisanalyzedonanelasticbasisforbothhotlegandcoldlegbreaks,thehotlegbreakatthesteamgenerator inletbeingthedetermining eventfortheSteamGenerator support.Thisanalysisisastaticanalysiswhichemploysthecompu(p)code51EC-21(HareIslandpipingflexibility code)-.BothLOCAanddes'ignseismicloadsareincludedintheanalysis.

2.2.2ECCSandOtherConnected PipingTheanalysisofthestressesgenerated intheECCSlinesandotherlinesattachedtotheprimaxyloopinvolvedatwostepprocess.First,thetimehistories ofthedis-placements aregenerated ateachnozzleattaching saidpipingtotheprimaryloop.The"worst"timehistory,irrespective ofthelocationatwhichisoccursis appliedtothelinewhichbyconfiguration andotherloading(normalandseismic)wouldresultinthehigheststresses.

ThestressesinducedbyLOCAmotionsforthisparticular configuration areadded-topreviously computednormalandseismic(SRSS)stresses.

Thedetermining breakforECCSlineevalua-tionisthecoldlegnozzlebreakinthecavity.2.2.3ReactorCoolantPipingThestructural modelfortheprimarysystemisalsoutilizedtodetermine thestressconditions intheintactportionofthereactorcoolantloop.3.0RESULTSOFTHEANALYSES3.1VesselSuortsTheloadscalculated foreachreactorvesselsupportbythemethodoutlinedinSection2.1.4arereportedinTable3forthebreakchosenfortheanalysis; i.e.,the4.0sq.ft.coldlegbreakattheinletnozzle;forarangeofreactorvesselsupportstiffnesses.

Thisrangecoversthepossiblevaluesoftheoverallstiffness oftheindividual'actor vesselsupports, therealvaluebeingsomewhere betweenthetwoextremes.

Itisnotpossibletoquantifythestiffness valuemoreprecisely sincethemodelling oftheboundarycondition representing embeddedsteelinthebiological shieldissubjecttovariation.

Inthesupportanalyseshowever,thehigherloadsresulting fromtheuseofthehigheststiffness, havebeenutilized.

Thisinsuresagainthattheabsolutemaximumloadpersupportiscomputed.

Inreality,lowervaluesareexpected.

Thecapability ofthereactorvesselsupportsisgiveninFigure4andTable4respectively fortheRPVsupportpadcapability andtheweakestlinkinthesteelsupport/biolo-gicalshieldstructure.

Sincethecapability ofthesupportsexceedthemaximumloadscomputedforthegivenbreak,itisconcluded thattheexist-ingsupportsystemisadequateforthatbreak.AsstatedinSection2.1,itispossiblethat,asaconsequence ofthebrokendischarge linerotationaboutthepump,alargerbreakareacouldformwithinthecavity,uptoamaximumof7.78sq.ft.Thislargerbreakarea,requiring aproportion-atelylongertimetoopen,hasvirtually noeffectonthrustandinternalasymmetric loads,butwouldincreasethehorizontal externalasymmetric loadbyapproximately 15-20percentoverthat usedintheanalysis, asexplained inSection2.1.2.TheEALrepresents approximately 40percentoftheoverallload.Hence,a20percentincreaseinthisloadwouldresultinlessthana10percentincreaseintheoverallloading.FromTable4andFigure4,itcanbeseenthatthisincreasewouldbeaccommodated bythemarginsexistinginthesupportsystem.Itistherefore concluded thatthereactor'essel supportscanwithstand thelargestbreakinthecoldlegpipingwithinthecavity.SincecoldlegbreaksoutsidethecavitydonotproduceEALloadsandsincethe'IALisvirtually unaffected bytheareaofthebreakasexplained inSection2.1.3,itisalsoconclu-dedthatthereactorvesselsupportsarecapableofwithstanding anyloadresulting frompostulated rupturesoutsidethecavity.Adetailedanalysisofthereactorloadsresulting fromhotlegbreakswithinthecavityhasnotbeenperformed.

Themasonsareasfollows:thestiffness ofthehotleg,pipecombinedwiththesteamgenerator restraining action,resultsinabreakareawithinthecavitywhichissmallerthanthecoldlegbreakarea,henceresulting EALwouldbelowerthancalculated forthecoldlegbreak;althoughthethrustforceinitially wouldbelarger,theIALwouldnotbecolinearwiththrustandEAL,butwouldinfactbeapproximately orthogonal tothem.Theresultant horizontal loadsonthevesselsupportstherefore, wouldclearlybesmaller.Forinstance, thereactions atreactorvesselsupports, duetoahotlegbreakhavebeencomparedtothereactions duetoacoldlegbreakforthrustandsubcompartment pressureonly.Horizontal HotLeBreak(Kis)Horizontal ColdLeBreak(Kis)ColdLegSptHotLegSpt427032703275Althoughtheloadonthecoldlegsupportismoresevereforahot.legbreakthanforacoldlegbreak,whentheeffectsofinternalasymmetric loads-are added,thecoldlegbreakwillgovern.Verticalloadswouldbeofthesame'order ofthoseexperienced asaresultofcoldlegbreaks,andthecapacityofthesupportsystemtoaccommodate verticalloadsissignificantly higherthanitshorizontal capability.

Henceclearlythereactorvesselsupportsystemisalsocapableofwithstanding theeffectsofpostulated hotlegbreaksinsideandoutsidethereactorcavity.

Asimilarconclusion hadbeen,reachedinourAugust1977report.Differences inmaximumloadsreportedhereinfromthosereportedintheAugust1977reportaretwofold.TheAugust1977reportdidnotconsiderinternalgapsorgapsbetween'he supportpadsandthesupportstructure.

TheAugust1977reportconsidered therefore thatallloadedsupportswouldbeloadedsimultaneously andsharetheloadequally.Theagreement oftheoverallloading.betweenthepresentandtheAugust1977results,confirmthattheapproachtakenin1977toassesstheloadswasnotunreasonable.

3.2OtherRCSSuortsTheonlysupportsontheprimarysystem,otherthanthevesselsupports, arethesteamgenerator supports.

Resultsoftheanalysesoftheloadsimposedonthesesupportsfrombothhotandcoldlegbreaksinthesystemincombination withseismicloads,indicated thatnoneofthedesignloadshavebeenexceed-ed,withexception oftheloadsonthefourholdownboltsatthevesselendofthesteamgenerator slidingbaseandtheslidingbaseitself.ThecomputedanddesignloadsareshowninTable5.Individual examination oftheslidingbase,thebolts,andboltanchorages howeverindicates thatallcanacceptably withstand theappliedloads.Itistherefore conclu-dedthattheexistingsupportsdesignisadeq'uate.

3.3ReactorCoolantPiinTable6reportstheelastically calculated piperupture-andseismicloadsonintactreactorcoolantpipingassociated withthebrokenloopfortheworstbreak,whichisthecoldleg.guillotine breakatthevesselsafeend.Examination ofthistablerevealsthatallloadsfallwithintheallowable loadswiththeexception oftheloadattheRCPdischarge nozzle,whichexceedtheallowable byabout,l3percent,onanelasticbasis.Sincethisanalysis~ispredicated ona4.0sq.ft.coldlegbreak,bythearguments presented inSection3.1,consideration ofthelargestbreakthatcouldoccuratthevesselsafeend;i.e.,7.78sq.ft.,requiresthatanincreaseinloadoflessthan10percentbeexaminedtoassessthea'dequacy ofthecoolantpiping.Suchanincrease'can bereadilyaccommodated attheRCPsuctionandRVoutletnozzles.TheRCPdischarge wouldbemoreoverstressed (onanelasticbasis)andtheRVinletwouldbeveryslightlyoverstressed.

Sinceonlythefluidretaining integrity ofthiscoolantpipingneedstobemaintained duringthepostulated LOCA,ananalysisconducted onanelasto-plastic basiswouldconcludethatthis integrity wouldbemaintained atthosenozzles.Sincetheamountofoverstressing calculated onanelasticbasisisrelatively small,aplasticanalysiswasnotconsidered necessary.

Duringtheperformance ofthisparticular'analysis itwascalculated thatthesnubbersonthereactorcoolantpumpsareoverstressed.

Thesesnubbe~arenotneededfortheseevents.Howevertheirfailurecouldaffecttheresults.Hence,theanalysiswasrepeatedbytakingnoaccountofthesnubbers.

ResultsarealsoreportedinTable6~Ascanbeclearlyseen,theeffectofthepresenceorabsenceofthesnubbersisnegligible.

3.4ECCSandConnected PiinThestressescomputedfromtheanalysisdescribed inSection2.2.2arewithin10percentoftheallowable, andhenceitisconcluded thattheECCSpipingandotherpipingconnected totheprimaryloop,isnotadversely affectedbythepostulated event.Table7comparesthepeakcomputedstresses, whichincludenomalandseismicloadstotheallowable stresses.

Themarginexistingbetweenpeakstressescalculated onanelasticbasisandstressesthatwouldbeallowedwithinanelasto-plastic analysisfurtherindicates thatthisattachedpipingwouldbeabletowithstand theimposedloadsfromthe7.78sq.ft.largercoldlegguillotine break.3.5SeismicLoads,PursuanttotheStaff'srequestattheJanuary16,1980meeting,Table1providesthedesignseismicloadsatthevarioussupportpointsintheReactorCoolantSystem.3.6ControlElementAssemblies AlthoughtheanalysisoftheControlElementDrivesresponsetopostulated LOCAeventsisinprogress, butwillnotbecomple-teduntilJuly1980,i'tisgermanetopointoutthattheCEAsarenotneededforbreaks'intheRCSwhichexceed0.5sq.ft.Theassumption ofacompleteguillotine willresultinbreakslargerthan0.5sq.ft.

4.0CONCLUSION

Eventhoughsomeanalyseshavenotyetbeencompleted, resultsobtainedtodatedemonstrate thattheexistingdesignhassignifi-cantcapabi/jtyl)o accommodate thepostulated events.Additional informatio~

whichhasbecomeavailable sincetheAugust1977report,andwhichreinforces ourcontention, statedinthatreport,demonstrates thatsucheventsareofanacceptably lowprobability andcannothappeninthemannerpostulated forthisanalysis.

Theforegoing reaffirms ourconclusion thatthedesignofSt.LucieUnitlisacceptable.

5.0REFERENCES

-"PLAST-AnElasto-Plastic ComputerProgramforStressAnalysisof3-DPipingSystemsandComponents SubjecttoDynamicForces",submitted totheNRCasETR-1001-EbascoTopicalReport.-St.LucieUnitNo.1FSAR,DocketNo.50-335,Amendment 44.*2/-"RELAP4-AComputerProgramforTransient ThermalHydraulic Analysis3/ofNuclearReactorsandRelated,Systems",

User'sManual,ANCR-NUREG-1335.

-Fabic,S.,ComputexProgramWHAMforCalculating

Pressure, Velocity4/andForceTransients inLiquidFilledPipingNetwork",

KaiserEngineering ReportNo.67-49-R,November1967.-"ICESSTRUDLII-TheStructural DesignLanguageEngineers User'sManual",MITPress,Cambridge, Massachusetts, 1968.-"ADMASS-AComputerCodeforFluidStructure Interaction UsingtheFinite6/ElementTechnique",

EbascoServices, Incorporated, 1979.-"DAGS-CENPD168,Revision1-DesignBasisPipeBreaks",September 1976.-"DFORCE-DesignBasisPipeBreaks",September 1976.-"MSC/NASTRAN

-User'sManual",McNealSchwandler Corporation, LosAngeles,California.

-"WCAP9570Class3-Mechanistic FractureEvaluation ofReactorCoolant10/PipeContaining aPostulated Circumferential ThruWallCrack",byPalusamy, S.S.,andA.J.Hartmann, October1979.-Ayers,D.J.andT.J.Griesbach,

'-'Opening andE~tension ofCircumferential CracksinaPipeSubjected toDynamicLoads",FifthInternational Conference ofStructural Mechanics inReactorTechnology, Berlin,Germany,1979.-Griffin,J.H.,"MEC-21-APipingFlexibility AnalysisProgram",

TID-4500(31stedition),

LA-2924,UC-38,July14,1964.

TABLE1ST.LUCIE1NORMALANDSEISMICSUPPORTLOADS(X106LB.)

CONDITION LOADH1V1NV10.GGG4195.0281.155i.360IIOAMALOPEIIATING THEGMAL+DEADDEADVIEIGHTV(EIGHT.005.032ODESEISMICSY.002.335-.G44-.04G.011.064DBESEISSIICSY.005.6701.288-.092IfNAV1V$tVHZV2NV2.G64a.195-.091.72Gk.2151.226.017.001.253+.355-.264-.3802.452035.003.507+.710-.528.761ivtI$$ACIOIIV$$$($$Vt(OIIIA(ACIIO(N V3NV3Z11Z12Y1Y2Y3Y4xNYx.19500.300.3001.3001.3000a.376.741%.215.367000.3151.009.3200S.30000.016-.057.086-.0540.0791.139-.019-.060.G2300-.019.155.417.1520.270-.349.743S.19541970.060-.07105802.278-.00600.033-.1'14.173-.1080-.038~120.50G00-.039211.835.3050.540.6SS.746S.390S.3940.121.143.1160Y$$($YI.vhVf$(fANC(N(AAION LOW(N$V(YOA1$YI($($N Table2Comparison ofPeakCalculated andDesignSeismic(DBE)LoadsatRepresentative Locations Design(Kips)Horizontal VerticalCalculated (Kips)Horizontal VerticalColdLegSptHotLegSptl,2937622,455.1,268522.6515.0354.6429.4 Table3St.LucieUnitfi'1RVSUPPORTIfAXABSREACTIONS (KIPS)-LOCA+SEISMIC(SRSS)4FTCLGBREAKATNOZZLElAOR2ALOCATIONS 8'1ASPPTRVSPPTSTIFFNESS VALUESK='4.62x10lb/in6K~59.71x10lb/in6K=77.54x10lb/in6-K=75.83x10lb/in6VerticalHorizontal 1397150223171587ulBSPPTVerticalHorizontal 2800533122515473-HotLegSPPTVerticalHorizontal 3458749330487777ForLOCA+Nopreactions, addthesevaluestotheverticalresults:~21ASPPT710~K81BSPPT726.KHotLegSPPT1157K+Forbreakatnozzle1Bor2B,theloadsonthecoldlegsupportswouldbereversed Table4St,Lucie1ReactorPressureVesselSupportCapacitySteelsupportstructure

-horizontal 8400kips*(concrete islimiting)

Steelsupportstructure

-verticaldownward12000kipsReactorCavityWallReactorCavityWallReactorSupportPadsReactorSupportPadshorizontal verticalhorizontal vertical".13000kips*~notlimitingSeeFigure4SeeFigure4Loadonindividual girder*<Allowable resultant asymmetric mechanical loadtransmitted alonggirderstoconcrete, basedonrebarmeanaxialstress'being withinyield.

TABLE5STEAMGENERATOR LOWERSUPPORTCALCULATEDANDDESIGNLOADSIREFERTOTABLE1FORSYMBOLS)SUPPORTZ11Z12FRONTY1SIDEY2BACKY3SIDEY4X-STOPZ1Z2CLGUILLNO.1+DBEIRSS)727806-406.9-756.5-605.0-300.178194301HLGUILLNO.2+DBEIRSS)42-2487.7-1176.4+1249.0-1175.9-5194.92784040DESIGNLOADLOCA+DBE3,600-1,868"-1,770-1I737-,691-1,7345,648,301-1,5741,800IKANDFT-KIPS)9gSTEAMGENERATOR/

SLIDINGBASESUPPORTSKIRTINTERFACE

.FxFyFz'xMzIHLGUILL)LOCA5205-3582M609RSSLOCA5DBE5205-35826.8418.34614SLIDINGBASEDESIGNLOADS5653-2,471.011.032.024.01003"ANEGATIVESIGNMEANSTENSION Table6St.LucieUnitIIlReactorCoolantSystemReactorPressureVesselandReactorCoolantPumpNozzleLoadsDuetoa4ftReactorVessel1AInletNozzle-Guillotine BreakPIPERUPTURERSSMOMENT(In-Kis)NozzleRCPDischarge RCPSuctionRVInletRVOutletRCPSnubber109,30050,50071,75050,150RCPSnubberNotAc~tin109,60054,55071,91050,170SeismicMoment(In-Kis)5,9107,2565,2722,535Allowable Moment(In-Kis)96,81078,96578,965279,340 Table7St.LucieUnitNo.1Connected PipingStressesCalculated vs.Allowable 4.0sq.ft.CLGInletBreakDesignPoint(RefertoFiure5)Calculated Stress(Eu.10ASME)Allowable Stress3X5639,07075,152*75,030*41,83543,47547,69033,43020,17148,60048,60048,60048,60048,60048,60048,60048,600Functionability andintegrity areassuredifLevelB(upsetconditions) limitsoftheASMEBoilerandPressureVesselCode,SectionIII,Division1arenotexceeded.

Functionability isimportant atpoints5and6wherethevalveis.Atpoints2and3,theselimitsareexceeded.

However,LevelD(faultedlimits)arenotexceededatthesetwopoints.LevelDlimitsareusedtodemonstrate thatintegrity ismaintained.

Equation(9)atthosetwopointswouldyield45,043psi.and44,479psirespectively withanallowable of48,600psi.

FIGURE1RELAP4510DELFORST.LUCIEPR)MARYCOOLANTSYSTEM3')3256004591160305731$131458839615168123377462634862eoo91063951123241Z1314153116175419204$414245462122255123472448QS3,265973500>>378551767S4948476152(A1)8081536335(81)717043424140Q6955S6S7Qoo'(a2)98VAt.VB74734645(82)Q72 FIGURE2ST.LUCIE1RCS-V/HAM/6MODELFORIALpssQssQss107741060721087110410310111312102811482020187538658eo8583~84891091107069>>5757677g1148P8178821Q117018192013'4261828270,0,0,800477946Qs20101681512191631495157956261962'00996766242598Qss003542224303844,7746230~3932Qss3340(A1)(81)41Qss4552oo5358604269614I76075747338041554962=56P1P14P10~~Xo>>904072120697167118~83070Pso211220~BRGAKP5(A2)P18(82)

FIGUPESAST.LUCIE1REDUCEDMODELOFREACTORINTERPeALS UGS38'A18:AZ'2.16HX-DIRIS//TOOUTLETNOZZLES'"

28I10'926'4,',22',FUEL'CORESHROUD.CSB20,A13HLEGENDA~AXIALGAPH=HORIZONTAL GAP//=PRELOADED COUPLING=GAPCOUPLING=COLINEARCONNECTOR

'SEEFIGURE3bFORDETAILSOFREACTORVESSELSANDPIPING v1'FIGURE38STLUCIE1REDUCEDMODELOFREACTORCOOLANTSYSTEMTOS.G.NO.1'rrro99189999REACTORVESSELHOTLEGTOS.G.NO.29909INTERNALS

'SEEFIGURE3aFORDETAILSOFINTERNALS) 9905rr~ro9914o9913oLUMPEDMASS0POINTOFAPPLIEDFORCE

.FIGURE4ST.LUCIE1.-:REACTORPRESSUREVESSELSUPPORTPADCAPABILITY IhC'K-10HOTLEGSUPPORT,='4.0SO.FT.CLG'COMPUTED MAXLOADSi(LOCA+SEISMIC+Mop)IQA(HOTLEGSUPPORTQB!VNBROl<EN COLDLEGSUPPORTBROI<ENCOLDLEGSUPPORTQA~l'0Z'I0'40:~ICOLDLEGSUPPORTSp.1;2.3'.4:5I6:7.,8,9,10..1112;13:14,15,-16 Rqx10(K)VERTICALLOAD.

FIXED"-~45,-37x3536DISPLACEMENTS SPECIFIED 302942432883027274510314511'l2FlGURE5':24-FIXEDSAFETYINJECTlQNLINE1-8-1(PREVIOUS 972)FLGRIDAPORFB8LIGHTOOMPANYSTLUCIENO.113141517~O2120182322t

'<'s~I

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