ML17319A636

Safety Analysis for Operation of DC Cook Unit 2 W/Positive Moderator Coefficient.

ML17319A636
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Site:	Cook
Issue date:	09/22/1980
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Attachment 2toAEP:NRC:00453 Transient Reanalysis Report

'SAFETYANALYSIS'OR OPERATION OFD.C.COOKUNIT2WITEA'OS'ITIVE MODERATOR COEFFICIENT INTRODUCTION Thissafetyanalysishasbeenperformed tosupporttheproposedTechnical Specification changeforD.C.CookUnit2whichwouldallowasmall,positivemoderator temperature coefficient toexist.atpowerlevelsbelow70percentpower.Theresultsoftheanaly-sis,wnicharepresented below,showthattheproposedchangecanbeaccommodated withamplemargintotheapplicable FSARsafetylimits.ThepresentD.C.CookUnit2Technical Specifications requirethemoderator temperature coefficient (MTC)tobezeroornegativeatalltimeswhilethereactoriscritical.

Thisrequirement isoverlyrestrictive, sinceasmallpositivecoefficient atreducedpowerlevelscouldresultinasignificant increaseinfuelcycleflexibility, butwouldhaveonlyaminoreffectonthesafetyanaly-sisoftheaccidenteventspresented intheFSAR.TheproposedTechnical Specifications change,giveninAttachment 1totheletter,allowsa+5pcm/'F*MTCbelow70percentofratedpower,changingtoa0pcm/'FMTCat70percentpowerandabove.ThisMTCisdiagrammed inFigurel.Apower-level dependent MTC*1pcm=10hk/k waschosentominimizetheeffectofthespecification changeonpostulated accidents athighpowerlevels.Moreover, asthepowerlevelisraised,theaveragecoolanttemperature becomeshigherasallowedbytheprogrammed averagetemperature controller fortheplant,tendingtobringthemoderator coefficient morenegative.

Also,theboronconcentration canbereducedasxenonbuildsintothecore.Thus,thereislessneedtoallowapositivecoefficient Iasfullpowerisapproached.

Asfuelburnupisachieved, boronisfurtherreducedandthemoderator coefficient willeventually becomenegativeovertheentireoperating powerrange.ACCIDENTANALYSISTheimpactofapositivemoderator temperature coefficient ontheaccidentanalysespresented inChapter14oftheD.C.CookUnit2FSAR(1)hasbeenassessed.

Thoseincidents whichwerefoundtobesensitive topositiveornear-zero moderator coefficients werereanalyzed.

Ingeneral,theseincidents arelimitedtotransients whichcausethereactorcoolanttemperature toincrease.

Withoneexception, theanalysespresented hereinwerebasedona+5pcm/'Fmoderator temperature coefficient, whichwasassumedtoremain-constantforvariations intemperature. Theanalysisinwhichthiswasnotthecase,wasthecontrolrodejectionanalysiswhichwasbasedonacoefficient equalto+5pcm/Fatzeropowernominalaveragetemperature andwhichbecamelesspositiveforhighertemperatures.

Thiswasnecessary sincetheTWINKLEcomputercode,onwhichtheanalysisisbased,isadiffusion-theory coderatherthanapoint-kinetics approximation andthemoderator temperature feedbackcannotbeartificially heldconstantwithtemperature.

Forallaccidents whichwerereanalyzed, theassumption ofapositivemoderator temperature coefficient existingatfullpowerisconservative sincetheproposedTechnical Specification requiresthatthecoefficient bezeroornegativeatorabove70percentpower.Zngeneral,thereanalysis wasbasedontheidentical analysismethods,computercodes,andassumptions employedintheFSAR;anyexceptions arenotedinthediscussion ofeach,incident.

Accidents notre-analyzedincludedthoseresulting inexcessive heatremovalfromthereactorcoolantsystemforwhichalargenegativemoderator coefficient ismorelimiting, andthoseforwhichheatupeffectsfollowing reactortriparenotsensitive tothemoderator coefficient.

TableIgivesalistofaccidents presented intheD.C.CookUnit2FSARanddenotesthoseeventsreanalyzed forapositivecoefficient.

Z.Transients NotAffectedBaPositiveModerator Coefficient Thefollowing transients werenotreanalyzed sincetheyeitherresultinareduction inreactorcoolantsystemtemperature andaretherefore

~'~sensitive toanegativemoderator temperature coefficient, orareotherwise negligibly affectedbyapositivemoderator temperature coefficient.

A.RCCAMisa'linment/Dro TheRCCAdropcasepresented inSection14.1.3oftheFSARispotentially affectedbyapositivemoderator temperature coefficient.

Useofapositivecoefficient intheanalysiswouldresultinalargerreduction incorepowerlevelfollow-ingtheRCCAdrop,therebyincreasing theprobability ofareactortrip.Forthereturntopowerwithautomatic rodcontrolcase,apositivecoefficient (whichwouldonlyexistbelow70percentpower)wouldresultinasmallincreaseinthepowerovershoot.

Westinghouse hasperformed extensive analysesinthisarea.whichhasdemonstrated thatthelimitingconditions forthistransient areatornear100percentpowerwherethemoderator temperature coefficient mustbezeroornegative.

Onthisbasis,theanalysisforthiseventwasnotrepeated.

B.StartuofanInactiveReactorCoolantLooAninadvertent startupofanidlereactorcoolantpumpresultsinadecreaseincoreaveragetemperature.

Asthemostnega-tivevaluesofmoderator reactivity coefficient producethegreatestreactivity

addition, theanalysisreportedintheFSAR,Section14.1.7,represents'he limitingcase.

Ig'~'-5-C.'xc'e's'sive'e'atR'emova'1 Du'et'o'.

Fee'dwater

'S'stemMa'1'funct'ions Theadditionofexcessive feedwater orthereduction offeed-watertemperature areexcessive heatremovalincidents, andareconsequently mostsensitive toanegativemoderator temperature coefficient.

Resultspresented inSection14.1.10oftheFSARJlbasedonanegativecoefficient, represent thelimitingcase.D.'xcessive Lo'adincreaseAnexcessive loadincreaseevent,inwhichthesteamloadexceedsthecorepower,resultsinadecreaseinreactorcool-antsystemtemperature.

Withthereactorinmanualcontrol,theanalysispresented inSection14.1.11oftheFSARshowsthat,thelimitingcaseiswithalargenegativemoderator coefficient.

Xfthereactorisinautomatic control,thecontrolrodsarewithdrawn toincreasepowerandrestoretheaveragetemperature totheprogrammed value.TheanalysisofthiscaseintheFSARshow@that theminimumDNBRisnotsensitive tomoderator temperature coefficient.

Therefore, theresultspresented intheFSARarestillapplicable tothisincident.

E.Los's'fNormalFeedwater, LossofOffsitePowerThelossofnormalfeedwater andlossofoffsitepoweracci-dents(Sections 14.1.9and14.1.12oftheFSAR)areanalyzedtodetermine theabilityofthesecondary systemtoremovedecayheat.Theseeventsarenotsensitive toapositive moderator coefficient sincethereactortripoccursatthebeginning ofthetransient beforethereactor,coolantsystemtemperature increases significantly.

Therefore, theseeventswerenotreanalyzed.

F.RutureofaMainSteamPieSincetheruptureofamainsteampipeisatemperature reduc-tiontransient, minimumcoreshutdownmarginisassociated withastrongnegativemoderator=temperature coefficient.

Theworstconditions forasteamline breakaretherefore thoseanalyzedintheFSAR(Section14.2.5).G.L'ossofCoolantAccident(LOCA)Thelossofcoolantaccident(Section14.3oftheFSAR)isanalyzedtodetermine thecoreheatupconsequences causedbyaruptureofthereactorcoolantsystemboundary.

Theeventresultsinadepressurization oftheRCSandareactorshutdownatthebeginning ofthetransient.

Thisaccidentwasnotreanalyzed sincetheTechnical Specification requirement thatthetemperature coefficient bezeroornegativeat70percentpoweroraboveensuresthatthepreviousanalysisbasisforthiseventisnotaffected.

XZ.Transients Sensitive toaPo'sitive'od'erator'o'e'ffi'c'i'ent A.pron'ilut'i"on AsstatedinSection14.1.5oftheFSAR,anuncontrolled borondilutionincidentcannotoccurduringrefueling due'toadmin-istrative controlswhichisolatethereactorcoolantsystem

~~I-7-fromthepotential sourceofunborated water.Ifaborondilutionincidentoccursduringstartup,theFSARshowsthattheoperatorhassufficient timetoidentifytheprobl'emandterminate thedilutionbeforethereactorreturnstocriti-cality.Therefore, thevalueofthemoderator coefficient hasnoeffectonaborondilutionincidentduringstartup.Thereactivity additionduetoaborondilutionatpower'ill causeanincreaseinpowerandreactorcoolantsystemtemperature.

Duetothetemperature

increase, apositivemoderator coefficient wouldaddadditional reactivity andincreasetheseverityofthetransient.

Withthereactorinautomatic control,however,therodinsertion alarmsprovidetheoperatorwithadequatetimetoterminate thedilutionbeforeshutdownmarginislost.Aborondilutionincidentwiththereactorinmanualcontrolisnomoreseverethanarodwithdrawal atpower,whichisanalyzedbelowandtherefore

'thiscasewasnotspecifically analyzed.

Following reactortrip,theamountoftimeavailable beforeshutdownmarginislostisnotaffectedbythemoderator coefficient.,

B.'ontrol RodWithdrawal FromaSubcritical Con'di:t'i.'on Intro'duction Acontrolrodassemblywithdrawal incidentwhenthereactorissubcritical resultsinanuncontrolled additionofreactivity leadingtoapowerexcursion (Section14.1.1oftheFSAR).The nuclearpowerresponseischaracterized byaveryfastriseterminated bythereactivity feedbackofthenegativefueltemperature (ie.Doppler)coefficient.

Thepowerexcursion causesaheatupofthemoderator andfuel.Thereactivity addition'ue toapositivemoderator coefficient resultsinincreases inpeakheatfluxandpeakfuelandcladtemperatures.

MethodofAnalsisTheanalysiswasperformed intheFSARforareactivity inser-tionrateof75pcm/sec.However,thisvaluewasfoundtobeoverlyconservative basedontheactualcyclevaluesforD.C.CookUnit2(2).Areactivity insertion rateof60pcm/secwhichisstillaveryconservative valuewasusedintheanalysiswithapo'sitive moderator coefficient.

Thisassumedreactivity insertion rateisgreaterthanthatforthesimultaneous withdrawal ofthecombination ofthetwosequen-tialcontrolbankshavingthegreatest.

combinedworthatmaximumspeed(45inches/minute)

.Aconstant.

moderator temperature coefficient of+5pcm/'Fwasusedintheanalysis.

Thedigitalcomputercodes,initialpowerlevel,andreactortripinstrument delaysandsetpointerrorsusedintheanalysiswerethesameasusedintheFSAR.ResultsandConclusions Thenuclearpower,coolanttemperature, heatflux,fuelaveragetemperature, andcladtemperature versustimefora60pcm/sec

~I~I-9-insertion rateareshowninFigures2through4.Thisinsertion rate,coupledwithapositivemoderator temperature coefficient of+5pcm/F,yieldsapeakheatfluxwhichdoesnotexceedthatpresented intheFSAR.Therefore theconclusions presented intheFSARarestillapplicable.

C.Uncontrolled ControlRodAssemblWithdrawa'1

'at.'o'wer Introduction Anuncontrolled controlrodassemblywithdrawal atpowerproducesamismatchinsteamflowandcorepower,resulting inanincreaseinreactorcoolanttemperature.

Apositivemoderator coefficient wouldaugmentthepowermismatchandcouldreducethemargintoDNB.Adiscussion ofthisincidentispresented inSection14.1;2oftheFSAR.MethodofAnalsisThetransient wasreanalyzed employing thesamedigitalcomputercodeandassumptions regarding instrumentation andsetpointerrorsusedfortheFSAR.Thistransient wasonlyanalyzedat100percentpowerwithapositivemoderator coefficient sincethiscaseisthemostlimitingofthosepresented intheFSAR.Aconstantmoderator coefficient of+5pcm/'Fwasusedintheanalysis.

Theassumption thatapositivemoderator coefficient existsatfullpowerisconservative sinceatfullpowerthemoderator coefficient willactuallybe'egative.

Forthi'scase,theDNBevaluation wasperformed usingtheimprovedthermaldesignprocedure (3). ResultsFigure5showstheminimumDNBRasa.functionofreactivity insertion rate.ThelimitingcaseforDNBmarginisare-activityinsertion rateof0.6pcm/secfromfullpowerinitialconditions whichresultsinaminimumDNBRof1.98.Apositivemoderator coefficient therefore doesnotlowertheDNBRassociated withacontrolrodassemblywithdrawal atpowerbelowthelimitvalueof1.80.Conclusions Theseresultsdemonstrate thattheconclusions presented intheFSARarestillvalid.Thatis,thecoreandreactorcoolantsystemarenotadversely affectedsincenuclearfluxandover-temperature hTtripspreventthecoreminimumDNBratiofromfallingbelow1.80forthisincident.

LossofReactorCoolantFlowIntroduction Asdemonstrated intheFSAR,Section14.1.6,themostseverelossofflowtransient iscausedbythesimultaneous losso'electrical powertoallfourreactorcoolantpumps.Thistran-sientwasreanalyzed todetermine theeffectofapositivemoderator temperature coefficient onthenuclearpowertran-sientandtheresultant effectontheminimumDNBRreachedduringtheincident.

Theeffectonthenuclearpowertransient wouldbelimitedtotheinitialstagesoftheincidentduring 1~iiIIQ~-11-whichreactorcoolanttemperature increases sincethisincreaseisterminated shortlyafterreactortrip.Method'fAnalsisAnalysismethodsandassumptions usedinthere-evaluation wereconsistent withthoseemployedintheFSAR.Thedigitalcomputercodesusedtocalculate theflowcoast-downandresulting systemtransient werethesameasthoseusedtoperformtheFSARanalysis.

Theanalysiswasdonewithaconstantmoderator coefficient of+5pcm/~FandtheDNBevaluation wasperformed usingtheimprovedthermaldesignprocedure (3).ResultsFortheanalysisperformed witha+5pcm/Fmoderator coefficient, thereactorcoolantaveragetemperature increases lessthan2'Fabovetheinitialvalue.Therefore, apositivemoderator coefficient doesnotappreciably affect.thereactorcoolantsystemresponseortheminimumDNBRreachedduringthetransient.

Forthiscase,aminimumDNBRof2.08wasobtained.

Figures6through8showtheflowcoastdown, thenuclearpowerandheatfluxtransients, andtheminimumDNBRversustime. Conclusions Apositivemoderator temperature'coefficient doesnotappreciably affecttheresultofthecompletelossofflowtransient, andtheminimumDNBRremainsabovethelimitvalueof1.80forthisincident.

Thiscasewasanalyzedsinceitisthemostlimitingonepresented intheFSAR.Sincethetransient causesonlyasmallchangeincoreaveragemoderator temperature, andthepositivemoderator coefficient doesnotappreciably affect.thenuclearpowertransient, thesinglepumplossofflowcaseswillalsonotbeappreciably affected.

LockedRotorXntroduction TheFSAR(Section14.1.6),showsthatthemostseverelockedrotorincidentisaninstantaneous seizureofareactorcoolantpumprotorat100percentpowerwithfourloopsoperating.

Following theincident, reactorcoolantsystemtemperature risesuntilshortlyafterreactortrip.Apositivemoderator coefficient.

willnotaffectthetimetoDNBsinceDNBisconservatively assumedtooccuratthebeginning oftheincident.

Thetransient wasreanlayzed, however,duetothepotential effectonthenuclearpowertransient andthusonthepeakreactorcoolantsystempressureandfueltemperatures.

Meth'odofAnalsisThedigitalcomputercodesusedinthereanalysis toevaluate thepressuretransient andthermaltransient werethesameasthoseusedintheFSAR.Theassumptions usedwerealsocon-sistentwiththoseemployedintheFSAR.Ananalysiswasdoneat70percentpowerwithamoderator coefficient of'+5pcm/'Finordertoshowthatthiscaseisnotmorelimitingthanthe100percentpower,0pcm/Fcasepresented intheFSAR.Thiscaseissufficient toillustrate theimpactonthetransient byapositivemoderator

.coefficient,sincethemoderator coefficient willactuallybezeroornegative-at fullpower.ResultsandConclusions TableIIcomparesresultsobtainedforthiscasewiththosepresented inthe-FSAR.Asshowninthetable,theFSARanaly-sisatfullpowerwithazeromoderator coefficient ismorelimitingthanthe70percentpowercasewithapositivemoderator coefficient.

Therefore, theconclusions presented intheFSARarestillapplicable.

L'ossofExternalElectrical LoadIntroduction Twocases,analyzedforbothbeginning andendoflifeconditions, arepresented inSection14.1.8oftheFSAR-l.Reactorinautomatic rodcontrolwithoperation ofthepressurizer sprayandthepressurizer poweroperatedreliefvalves;and 2.Reactorinmanualrodcontrolwithnocreditforpressurizer sprayorpower'operated reliefvalves.Asthemoderator temperature coefficient willbenegativeatendoflife,onlybeginning oflifecaseswererepeated.

Theresultofalossofloadisacorepowerlevelwhichmomentarily exceedsthesecondary systempowerremovalcausinganincreaseincorewatertemperature.

Theconsequences ofthereactivity additionduetoapositivemoderator coefficient.

areincreases inbothpeaknuclearpowerandpressurizer pressure'.

MethodofAnalsisAconstantmoderator temperature coefficient of+5pcm/~Fwasassumed.Themethodofanalysisandassumptions usedwereotherwise inaccordance withthosepresented intheFSAR.Theimprovedthermalprocedure (3)wasutilizedintheDNBevaluation.

ResultsThesystemtransient responsetoatotallossofloadfrom102percentpower,withcontrolrodsinautomatic control,assumingpressurizer reliefandsprayvalves,isshowninFigures9and10.PeakRCSpressurereaches2567psiafollowing areactortriponovertemperature hT.Thiscomparestoavalueof2493psiapresented intheFSAR.AminimumDNBRof2.30isreachedshortlyafterreactortrip. PFigureslland12illustrate reactorcoolantsystemresponsetoalossofloadwithrodsinmanualcontrol,assumingnocreditforpressurecontrol.PeakRCSpressurereaches'604 psiafollowing reactortriponhighpressurizer pressure.

ThepeakpressurereachedintheFSARanalysisforthiscasewas2597psia.TheminimumDNBRisinitially 2.71andincreases throughout thetransient.

Conclusions Theanalysisdemonstrates thattheintegrity ofthecoreandthereactorcoolantsystempressureboundaryduringalossofloadtransient willnotbeaffectedbyapositivemoderator reactivity coefficient sincetheminimumDNBratioremainswellabovethe1.80limit,andthepeakreactorcoolantpressureislessthan110percentofdesign.Therefore, theconclusions presented intheFSARarestillapplicable.

RuptureofaControlRod.DriveMechanism Housin/ControlRodE'ectionintroduction Therodejectiontransient isanalyzedatfullpowerandhotstandbyforbothbeginning andendoflifeconditions.

Sincethemoderator temperature coefficient isnegativeatendoflife,onlythebeginning oflifecaseswerereanalyzed.

Thehighnuclearpowerlevelsandhotspotfueltemperatures resulting fromarodejectionareincreased byapositive moderator coefficient.

Adiscussion ofthistransient ispresented inSection14.2.6oftheFSAR.Metho'dofAnalsisThedigitalcomputercodesforanalysesofthenuclearpower'ransient andhotspotheattransferarethesameasthoseusedintheFSAR.Theejectedrodworthsandtransient peakingfactorswerethesameasreportedinReference 3.Themoderator coefficient usedforthistransient was+5pcm/'Fatzeropowernominalaveragetemperature, decreasing toapproximately

+4pcm/'FatfullpowerT-a'verage.

Th'isisstillaconservative assumption sincethemoderator coefficient actuallyiszeroornegativeabove70percent.power.ResultsandConclusions Peakfuelandcladtemperatures andnuclearpowerversustimeforbothfullpowerandhotstandbyarepresented inFigures13through16.Acomparison ofreanalysis andFSARresultsispresented inTableIII.Thelimitingpeakhotspotcladtemperature, 2469F,wasreachedinthehotfullpowercase.Maximumfueltemperatures werealsoassociated withthefullpowercase.Althoughthepeakhotspotfuelcenterline temperature forthistransient exceeded-themeltingpoint,meltingwasrestricted tolessthantheinnermost 10percent.ofthepellet.Asfuelandcladtemperature donotexceedthefuelandclad limitsspecified intheFSAR,thereisnodangerofsuddenfueldispersal intothecoolant,orconsequential damagetotheprimarycoolantloop.Therefore, theeffectsofapositiveMTCofthemagnitude described aboveisacceptable.

SUMMARYInordertoassesstheeffectonaccidentanalysisofoperation ofD.C.CookUnit2withaslightlypositivemoderator temperature coefficient, asafetyanalysisoftransients sensitive toapositivemoderator coefficient wasperformed.

Thesetransients includedcontrolrodassemblywithdrawal fromsubcritical, controlrodassemblywithdrawal atpower,lossofreactorcoolantflow,lossofexternalload,andcontrolrodejection.

Thisstudyindicated thatasmallpositivemoderator coefficient doesnotresultintheviolation ofanyapplicable safetylimitsforthetransients analyzed.

Exceptasnoted,theanalysesemployedaconstantmoderator coefficient of+5pcm/F,independent ofpowerlevel.Theresultsofthisstudyareconservative fortheaccidents investigated atfullpower,sincetheproposedTechnical Specification requiresthatthecoefficient bezeroornegativeatorabove70percentpower.

REFERENCES l.DonaldC.CookNuclearPlant,Unit2,FinalSafetyAnalysisReport,Amendment 75,datedApril1977andsupplements, DocketNo.50-316.2.ReloadSafetyEvaluation Report,D.C.CookNuclearPlant,Unit2,Cycle2,July1979,(letterNo.AWF-311,8/17/79).

3.Chelemer, H.,Boman,L.H.andSharp,D.R.,"Improved ThermalDesignProcedure,"

WCAP-8567, July1975(Proprietary) andWCAP-8568 (Non-Proprietary).

TABLEIACCIDENTS EVALUATED FORPOS'ITIVE'ODERATOR COEFFICIENT EFFECTS'SARAccidentTimei:n'i:fe*14.1.1*14.1.214.1.3/4*14.1.5*14.1.614.1.7*14.1.81'4.1.914.1.1014.1.1114.1.12RCCAWithdrawal fromSubcritical RCCAWithdrawal fromPowerRCCAMisalignment/Drop BoronDilutionLossofPlow/Locked RotorStartupofanInactiveLoopLossofLoad/Turbine TripLossofFeedwater Feedwater,Malfunction Excessive LoadIncreaseStationBlackoutBOCBOCBOCBOCBOCEOCBOCEOCBOC/EOC14.2.5*14.2.614.2.8SteamLineBreakRCCAEjectionFeedLineBreak(Supplement)

EOCBOC14.3LOCABOC*Accidents Evaluated BOC-Beginning ofCycleEOC-EndofCycle TABLEIICOMPARISON QF'ESULTS'QR'OCKED'OTOR

'ANALYSES ThisStu'dFSARModerator temperature coefficient, hk/k/'F5x10-5Initialpowerlevel,percentofnominal70100Peakfuelpelletav.temperature,

'F22532906Peakcladtemperature duringtransient,

'F15861878Peakreactorcoolantsystempressure, psia25212633 TABLEIII"SU1SGWYOF'ODEJECTIONRESULTS'EGINNING

'OFCYCLE(ThisStudy)HotZeroPowerHotFullPowerMaximumfuelpelletaveragetemperature,

'F29354088Maximumfuelcentertemperature,

'F34404985Maximumcladaveragetemperature,

'F22212469Maximumfuelenthalpy, cal/gm121179Fuelpelletmelting,percent.<10

~~~~~Rl~CCC~MLL,4les5CLCLII3CCLLlCQaceULLlLCCCLLPChLaJCDCDKcJ010.2030405060708090100IPOMERFIGURE1MOOERATOR TEMPERATURE COEFFICIENT VSPOWERLEVEL C>C)SO-2.10310-'.02.5~5.07.510.012.515.0-17.5TIME(SECONOS)

FIGURE2RODWITHDRAWAL FROMSUBCRITICAL NUCLEARPOWERVSTIME.

CI~~p~~la0%50.I1000COREMATERCLADFUEL7505000.02.55.07.510.012.5-15.0'7.520';0TINE(SECONDS)

FIGURE3RODWITHDRAWAL FROMSVBCRITICAL TEMPERATURE VSTINE CDo0.Sc50.4I0.20.00.02.5~5.07.510.012.515.017.520.0TIME(SECQNOS)

FIGURE4ROOWITHORAWAL FROMSUBCRITICAL HEATFLUXVSTIME 2.4.2.322--HIGHNEUTRONFLUXTRIP2.0--OVERTBlPERATURE

.5T.TRIP9.40.81,02.0406.08.010.0REACTIVITY INSERTION (106AK/SEC)20.040..60.80.100.ftGURE5RODMITHDRAMAL ATPOWDER j.0O.S0.60.4TINE{SECONOS)

FIGURE6LOSSOFFLOMFLOWVSTINE 1.2&CD4J4CD+aseQ1.00.80.60.40.2HOTCHANNEL0.0'1.2~K~~LLCD~x44CDIeCQ1.'00.80.60.4AVERAGECHANNEL0.2Q.O010cled4LCDOUCDCJ+rCC1.21.00.80.60.40.2'.00.05.010.0TINE{SECONDS)

.15.020.0FIGURE7LOSSOFFLOMr!~0</sfs

~<p'~5';5~~~~

)t~~a~~'~-0h9.9;Z.gI1.52TINE(SECONDS)

FIGURE8LOSSOFFLOWDNBRVSTIME oI~I1%~~1~04lOCD0.6mu04.tL2'~~~~.25002400'n,2300Cll2200men210020001900a-1800.50.4.5.403.53.052.52.01.51.3~0~'0Zo30TIME(SECONOS) 50FIGURE9LOSSOFLOAOAUTOMATIC ROOCONTROLWITHPRESSURIZER RELIEFANOSPRAYC~

\I1~~~;NN~~1$g0~~~12501NO~150NOKO~e675ca650625~Pu6005755500102030TIME(SECONDS) 4050FIGURE10LOSSOFLOADAUTOMATIC RODCONTROLWITHPRESSURIZER RELIEFANDSPRAY LQClCQCD~CD~CD5~CDCC1.0080.60.402MO~~~1Vtttt~~tICC4/l~CllLalCCLIJ~t4CLCCCACf)telCgCL'26002500240023002200210020001900saooT.~C06.0555.04.5a.o3;53.02.52.0"0,'0II20',30tTIME{SECONOS) 50'IGURE11LOSSOFLOAOMANUALROOCONTROLNOPRESSURIZER RELIEFORSPRAY 560~~540~RO~~-'20MTT501500u-1250~~1000750V7C)50025005905805705601020.30TIME(SECONOS) 50FIGURf12LOSSOfLOAOMANUALRODCONTROLNOPRESSURIZER RELIEFORSPRAY

~f6.50.-002.TINE(SECONOS)

'FIGURE13ROOEJECTIONBOLHFPNUCLEARPOlrlERVSTINE 5000$000400030002000FUELCENTERTEMPERATURE FUELAYERAGETEMPERATURE CLADOUTERTEMPERATURE 4900'FMELTING100003TIME(SECONDS)

FIGURE14RODEJECTIONBOLHFPTEMPERATURE VSTIME 101.01.52.02.53.0TIME(SECONOS)

FIGURE15ROOEJECTIONSOLHZPNUCLEARPOMERVSTIME

'l~MOO'~~40003000IZOOOFUELCENTERTEMPERATURE FUELAVERAGETBIPERATURECLAOOUTER~i4IPERATUREj000-~Y~+1~O~'1~,~~,P~~TWE(SECONOS)

'IGURE16ROOEJECTIONBOLHZPTBlPERATURE VSTINE