ML17325A908

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Containment Integrity Analysis for Donald C Cook Nuclear Plant Units 1 & 2.
ML17325A908
Person / Time
Site: Cook  American Electric Power icon.png
Issue date: 07/31/1988
From: WELLS M E
WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:
Shared Package
ML17325A907 List:
References
WCAP-11908, NUDOCS 8808290261
Download: ML17325A908 (11)


Text

WESTINGHOUSE CLASS3WCAP-11908 CONTAIÃKN1'NTEGRITY ANALYSISFORDONALDC.COORNUCLEARPLANTUNITS1AND2M.E.-WILLSJuly1988WESTINGHOUSE ELECTRICCORPORATION NuclearEnergySystemsP.0.Box355Pittsburgh, Pennsylvania 15230 1

B.RadialXenonMethodo1ogyTheinsertion orwithdrawal ofcontrolrodswhilechangingpowerlevelcancauseradialxenonredistribution aswellasaxialxenonredistri-bution.SinceF(z)increases causedbyradialxenonredistribution cannotbemodeledintheaxialmodelusedtoevaluateF~,thisfactormustbetakenintoaccountwithseparatecalculations.

F~(z)increases duetoradialxenontransients areexplicitly includedinW(z)throughaheightdependent radialxenonfactor,Xe(z).Three-dimensional calculations areusedtoevaluateincreases inelevation dependent radialpeakingfactorsinaconservative mannerbyinducingaradialxenonoscillation.

Anequilibrium xenoncaseisperturbed byreducingpowerlevelandinserting controlrodsdeeplyenoughtoforcetheaxialfluxdifference tothemostnegativeallowedvalve.Thexenondistribution isallowedtochangeforsereralhoursinthisconfigura-tion,thenthecontrolrodsarewithdrawn andpowerisincreased.

Theresulting xenontransient isfollowedinshorttimesteps.ThemaximumvalueofFateachelevation occuringduringthetransient isusedxytodetermine Xe(z),where)maximum,transient xy(z,tequilibrium Fxy(z)ThefinalformofXe(z)isdetermined byconservatively boundingtheresultsofthetransient calculation.

ATTACHMENT 11TOAEPNRC1071EMAJORANALYTICAL ASSUMPTIONS SECTIONFROMWCAP-11908 I

],2MAJORANALYTICAL ASSUMPTIONS Th'eevaluation modelforthelongtermmassandenergyreleasecalculations usedwastheMarch1979modeldescribed inreference 1.Thisevaluation model'has-beenreviewedandapprovedbytheNRC,andhasbeenusedintheanalysisofothericecondenser plants.Forthelongtermmassandenergyreleasecalculations, operating temperatures forthehighestaveragecoolanttemperature casewereselectedastheboundinganalysisconditions.

Theuseofhighertemperatures isconservative becausetheinitialfluidenergyisbasedoncoolanttemperatures whichareatthemaximumlevelsattainedinsteadystateoperation.

Additionally, anallowance of+5'Fisreflected inthetemperatures inordertoaccountforinstrument erroranddeadband.

TheinitialRCSpressureinthisanalysisisbasedonanominalvalueof2250psi.Alsoincludedisanallowance of+30psi,whichaccountsfortheuncertainty onpressurizer pressure.

Theinclusion ofanadditional

+5psiuncertainty, suchthatthetotaluncertainty is+35psi,wouldhaveaninsignificant effectontheresults.Theselection of2250psi~~~~~~~~~~~asthelimitingpressureover2100psiisconsidered toaffecttheblowdownphaseresultsonlysincethisrepresents theinitialpressureoftheRCS.TheRCSrapidlydepressurizes fromthisvalueuntilthepointatwhichitequilibrates withcontainment pressure.

TherateatwhichtheRCSblowsdownisinitially moresevere,forthe2250psicasethanforthe2100psicase.Additionally theRCShasahigherfluiddensityforthehigherpressurecase(assuming aconstanttemperature) andsubsequently hasahigherRC8massavailable forrelease.Thus,2250psiinitialpressurewasselectedasthelimitingcaseforthelongtermmassandenergyreleasecalculations.

Theseassumptions conservatively maximizethemassandenergyintheReactorCoolantSystem.Itistheintentofthisanalytical efforttoprovideboundingcalculations thatwillcoverthefueltypeusednowandinthefutureforbothUnits1and2.Inordertojustifythis,theissueoffuelmustbeaddressed sinceUnit1currently operateswithWestinghouse fuel,andUnit2operateswithANFfuel.1504v;10/081588 1-2 Theselection offueltypeforthelongtermmassandenergycalculation andsubsequent LOCAcontainment integrity calculation isbasedontheneedtoconservatively maximizethecorestoredenergy.ThefueltypeinUnit1,whichisfor15x15OFAfuel,wasusedintheanalysisbasedonthefactthatthelargerdiameterrodscontainmorecorestoredenergythanthesmallerdiameterrodsofa17x17assembly.

Thus',theanalysisveryconservatively accountsforthestoredenergyinthecore.Regarding safetyinjection flow,themassandenergycalculation considers bothminimumandmaximumsafetyinjection flowrates.

Forthecaseofminimumsafetyinjection flow,theRHRcrosstievalveisassumedtobeclosed,inconjunction witha10/assumeddegradation inpumphead.ClosureoftheRHRcrosstiewasconsidered overtheHHSIcrosstiebecausethiswouldhaveamoresevereimpactontheanalysis(i.e.,closureoftheRHRcrosstiewouldboundclosureoftheHHSIcrosstie).

Thisresultsintheconservative minimumsafetyinjection flowrateused.Forthecaseofmaximumsafetyinjection flow,theRHRcrosstievalveisassumedtobeopen,andnodegradation inpumpheadcurvesisconsidered.

Thisresultsinthemaximumpermissible safety~~~~~~~injection flowrateused.Furtherdetailsabouttheseassumptions arecontained insection2.4.Thus,basedontheaboveconditions andassumptions, aboundinganalysisofUnits1and2ismadeforthereleaseofmassandenergyfromtheRCSintheeventofaLOCA.Inthecaseofthecontainment integrity peakpressurecalculations, theanalysiswillutilizetheLOTIC-1evaluation model,whichhasbeenreviewedandapprovedbythe,NRC.Thismodelhasbeensuccessfully usedfortheothericecondenser plantsintheirFSARanalyses, aswellasiniceweightreduction studies.AsinputtotheLOTIC-Icomputercode,mass,andenergyreleaseratesasdescribed inSection2ofthisreportwillbeused.Othermajoranalysisassumptions willbethatonedieseltrainwillbeassumedtofail,consistent withtherequirements toanalyzetheworstsinglefailure.Additionally, the1504v:10/081588 1-3 11 flowfromthecontainment spraypumpwillbedegradedby10%,conservatively allowingforfuturesystemdegradation.

Theicemassusedintheanalysiswas2.11millionpounds.Thisicemassisconsistent withthecurrenttechnical specification icemassbasis.1504v:10/0815B8 1-4

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