ML17207A876
| ML17207A876 | |
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| Site: | Saint Lucie  |
| Issue date: | 03/03/1980 |
| From: | FLORIDA POWER & LIGHT CO. |
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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.
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.
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.
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:
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.
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.
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.
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.
4.0CONCLUSION
Eventhoughsomeanalyseshavenotyetbeencompleted,resultsobtainedtodatedemonstratethattheexistingdesignhassignifi-cantcapabi/jtyl)oaccommodatethepostulatedevents.Additionalinformatio~whichhasbecomeavailablesincetheAugust1977report,andwhichreinforcesourcontention,statedinthatreport,demonstratesthatsucheventsareofanacceptablylowprobabilityandcannothappeninthemannerpostulatedforthisanalysis.TheforegoingreaffirmsourconclusionthatthedesignofSt.LucieUnitlisacceptable.
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.
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.
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
.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.
FIXED"-~45,-37x3536DISPLACEMENTSSPECIFIED302942432883027274510314511'l2FlGURE5':24-FIXEDSAFETYINJECTlQNLINE1-8-1(PREVIOUS972)FLGRIDAPORFB8LIGHTOOMPANYSTLUCIENO.113141517~O2120182322t
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