ML17321A900

Notifies of Error in 10CFR50.46 LOCA Analyses Performed for Facilities.Input Error in TOODEE2 Code Used to Calculate Fuel Rod Heatup Resulted in Rod Decay Heat Power Too Low & Subsequent Underpredicted Cladding Temp.Part 21 Related

ML17321A900
Person / Time
Site:	Robinson, Cook, 05000000
Issue date:	09/30/1985
From:	MALODY C SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER
To:	MARTIN J B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML17321A899	List: ML17321A898 ML17321A900
References
REF-PT21-85-431-000 PT21-85-431, PT21-85-431-000, NUDOCS 8510080301
Download: ML17321A900 (11)

Text

EQONNUCLEARCOMPANY,INC.2101HORNRAPIDSROAD.POBOX130.RICHLANDWA88352I50gi375-8100TEL%,-15.2878September30,1985Mr.JohnB.MartinRegionalAdministrator,RegionVUnitedStatesNuclearRegulatoryCommission1450MariaLane,Suite210WalnutCreek,CA94596

SUBJECT:

NotificationofErrorinLOCAAnalysesOearMr.Martin:AsreportedinatelephoneconversationonSeptember30,1985betweenMr.YuhasofRegionVandme,anerrorwasdiscoveredinthe10CFR50.46lossofcoolantaccident(LOCA)analysesperformedbyExxonNuclearfortheH.B.RobinsonUnit2andD.C.CookUnit1reactors.TheerrorwasaninputerrorintheTOODEE2codewhichisusedtocalculatefuelrodheatup.Theerrorresultedintheroddecayheatpowerbeingtoolowwhichcausedthecalculatedpeakcladdingtemperaturetobeunderpredicted.Attachedisadetaileddescriptionoftheeffectoferrorforeachunitandtheresultingunder-predictioninthepeakcladdingtemperatures.AllofthepressurizedwaterreactorsforwhichExxonNuclearprovidesLOCAanalyseshavebeenreviewed.Theerrorwasverifiedtohaveoccurredintheanalysesforonlythesetwoplants.ForD.C.CookUnit1,thecalculationwasrerunwiththeerrorcorrectedandusingmorerealisticvaluesofthepelletdensityandinternalpressure.Thisanalysiswasincompliancewiththerequirementsof10CFR50.46.ForH.B.RobinsonUnit2,thecalculatedPCTswiththeerrorcorrectedwereabove2200F.AreductioninFqwhichcorrespondstotheunderestimateoftherodpowerwasnecessarytomaintaincompliancewiththe10CFR50.46requirements.AsrequiredbytheExxonNuclearprocedures,aHazardsReviewBoardwasconvenedonSeptember28,1985whentheeffectoftheerrorshadbeendetermined.TheBoardconcludedthattheaffectedutilitiesshouldbenotified,thattheyshouldinturnnotifytheNRC,andthatH;B.RobinsonUnit2shouldimmediatelyreducetheallowedFqasindicatedintheattachment.Basedonsubsequentconversationswiththeaffectedutilities,theserecom-mendationshavebeenfollowed.851008030i8Si002'.pDR'"AoaCXOS00>>iS"p,-.-"-PDR.

Mr.J.Hartin(USNRC)September30,1985Thisletterprovidesthewrittennotificationusingtheproceduresgivenin10CFR21.21(b).Iftherearequestions,oriffurtherinformationisneeded,pleasecontactme.Sincerely,C.Malody,ManagerCorporateLicensinnaacc:Mr.R.DeYoung(3copies)(D/OIEUSNRC)Mr.J.Bell(AEPSC)Mr.T.Dresser(CPKL)

AttachmentErrorinLOCA-ECCSAnalysisforH.B.RobinsonUnit2andD.C.CookUnit1Ref.:(1)XN-NF-84-72,"H.B.RobinsonUnit2LargeBreakLOCA-ECCSAnalysiswithIncreasedEnthalpyRiseFactor,"ExxonNuclearCompany,July1984(2)XN-NF-84-72,Supp.1,"H.B.RobinsonUnit2LargeBreakLOCA-ECCSAnalysiswithIncreasedEnthalpyRiseFactor:BreakSpectrumAnalysis,"ExxonNuclearCompany,August1984.(3)XN-NF-84-72,Supp.2,"H.B.RobinsonUnit2LargeBreakLOCA-ECCSAnalysiswithIncreasedEnthalpyRiseFactor:K(Z)Curve,"ExxonNuclearCompany,August1984(4)XN-NF-83-61,"D.C.CookUnit1LOCA-ECCSAnalysisforExtendedExposure,"ExxonNuclearCompany,August1983(5)Letter,G.F.Owsley,Manager,ReloadLicensingLiaison(ENC)toRichardDeYoung,DirectorofInspectionandEnforcement(USNRC),datedMarch22,1985(GFO:85:010)TheLOCA-ECCSanalysesforthereactorsH.B.RobinsonUni,t2andD.C.CookUnit1reportedintheabovereferenceshavebeenfoundtocontainanerror.TheerrorwasintheinputtothecodeTOODEE2.ThecodeTOODEE2calculatesthethermalresponse(heatup)ofthehotfuelrodfollowingtheendoftheblowdowntransientuntilthecoretemperaturetransientisterminated.Thefuelrodsintheanalysesweremodeledwitheightradialringsinthefuelpellet.Theerrorconsistedoftheassignmentofarelativedecayheatpowerdensityof0.0intheouterringofthefuelpelletandresultedincalculatedpeakcladtemperatureswhichweretoolow.H.B.RobinsonUnit2AsummaryofthepeakcladtemperaturesfortheH.B.RobinsonUnit2analysis,reportedinReferences1,2and3,andofthecalculatedpeakcladtemperatures'iththeerrorcorrectedispresentedintheattachedTable1.ThefirstthreecasesinTable1wereoriginallyperformedaspartofanexposuresensitivitystudy,andthefinaltwocaseswereperformedtodefinetheaxialpowerpeakingfactordependence(K(2)curve).Ascanbeseenfromthetable,threeofthesecasesresultinpeakcladtemperaturesgreaterthan2200oFandthusexceedthe10CFR50.46criteria.AnanalysiswasperformedtodetermineanFqwhichwouldresultinpeakcladtemperatureslessthan2200oF.ThisrequiredareductioninFqof8XwhichwasachievedbyareductionofthehotrodpowerintheTOODEE2codeof8X.ThisisaconservativecalculationbecausetheFqintheblowdownportionofthetransienthasnotbeenreduced.TheinitialtemperaturesatthestartoftheTOODEE2(heatup)calculationarethereforeconservativewithrespecttotheFqintheTOODEE2calculation.AreductionoftheFqintheblowdownportionofthetransientwouldresultinthecalculationofevenlowertemperatures.TheresultsofthesecalculationsaresummarizedinTable2.

TheFqlimitsforH.S.RobinsonUnit2whichwillresultinLOCA-ECCScalculationalresultsinconformancewiththe10CFR50.46criteriaareshowninTable3.Thelimitsaredividedintotwoexposurerangesconsistentwiththeanalysis,0to9MWD/kgand9MWD/kgto49MWD/kg.D.C.CookUnit1TheerrorintheD.C.CookUnit1analysis(References4and5)occurredonlyinthecalculationforthecaseat48MWD/kg.Thecasesatlowerexposuresdonotcontaintheerror.Thecalculationinerrorwasrerunwiththeerrorcorrectedandmorerealisticvaluesforthepelletdensityandinternalrodpressure.Thereanalysisresultedinapeakcladtemperaturechangefrom1827Fto2189oF,whichisstillincompliancewith10CFR50.46.Thisrevisedcalculationisveryconservativeinthatthestoredenergyusedinthecalculationisthepeakstoredenergyovertherange0to48MWD/kgratherthanalowervalueofstoredenergythatwouldbeappropriateforthe48MWD/kgexposureforthiscase.Additionally,itisourunderstandingthattheENC-designedfuelinD.C.CookUnit1isnotintheexposurerangeforwhichthiscalculationisapplicable.

Table1H.B.RobinsonUnit2ErrorinTOODEE2Input;RodRadialPowerDistributionCaseDescription(Exposure/PowerShape)PreviousPeakCladTemperature(oF)CorrectedPeakCladTemperature(oF)BOL/Cosine9MWD/kg/CosineEOL/CosineBOL/TopPeaked9MWD/kg/TopPeaked20421815178521972183>220019231888>2200>2200 Table2H.B.RobinsonUnit2ReanalysiswithFq*.92inTOODEE2CalculationCaseDescription(Exposure/PowerShape)PeakCladTemperature(<<)BOL/CosineBOL/TopPeaked9MWD/kg/TopPeaked206421952187 Table3H.B.RobinsonUnit2LOCA-ECCSLimits0to9MWD/kgHotRodAveraeExposure9to49MWD/kgHotRodAveraeExposureX/L0.0000.5000.9161.000~F(Z)2.1302.1301.6900.8351.0001.0000.7930.392X/L0.0000.5000,9161.000~F(Z)2.3202.3201.7260.8351.0001.0000.7440.360 Attachment2toAEP:NRC:0940B OCTOfm85Hj(ONUCLEARCOMPANY,INC.210tHORNRD8ROAO.POBOXI30,RCHLANO,WA8835210O81318.81TLEX:tb2878Mr.JPropreIndiac/oOneRColuSUBJERef.:September30,1985JSH:044:85IIIltIsephL.8elltManager,D.C.CookUnit1a5NichiganElectricCompanyericanElectricPowerServiceCorp.',versidePlazaus,OH43216-6631T:ErrorinLOCA/ECCSAnalysisforD.C.CookUnit1(1)XN-NF-83-61,"D.C.CookUnit1LOCA-KCCSAnalysisforExtendedExposure,"ExxonNuclearCompany,August1983(2)Letter,G,F.Owsley,Manager,ReloadLicensingLiaison(ENC)toRichardOeYoung,DirectorofInspectionandEnforcement(USNRC),datedMarch22,1985(GFO:85:010)

Dearr.8ell:

ECCSerror)calcu)ofthhThefhpelletdensicalcuinthvalue~tempesunnathes0to;.4appropsdiscussedwithMr.GeorgeJohn(AEP)onSeptember28,1985,theLOCA-nalysisforD.C.CookUnit1reportedtinReferences1and2containsanTheerrorwasintheinputtothecodeTOOOEE2.ThecodeTOODEE2atesthethermalresponse(heatup)ofithehotfuelrodfollowingtheendblowdowntransientuntilthecoretemperaturetransientisterminated.elrodintheanalysiswasmodeledwitheightradialringsinthefuelTheerrorconsistedoftheassignmentofarelativedecayheatpoweryof0.0intheouterringofthefuelpellet.Thisresultedinaatedpeakcladtemperaturewhichwas'oolow.Theerroroccurredonlycalculationforthecaseat48MWD/kg.thecalculationinerrorwasrerunwiththeerrorcorrectedandwiththeodpelletdensityincreasedandtheinternalrodpressuredecreasedtoappropriatefor48MWD/kg.Thiscalculationresultedinapeakcladatureof2189oFincompliancewith10'CFR50.46.ThesecalculationsareizedinTable1.Thiscalculationisstillveryconservativeinthatoredenergyintheca'Iculationisth)peakstoredenergyovertherange8MWD/kgratherthanalowervalueofstoredenergythatwouldberiateforthe48MWD/kgexposureforthiscase.Additionally,itisourANASS<ATCOSEXXONCOIISaORATONI I~'SaIIS&&laI~IalMr.J.Bell(AEP)JSH:044:85September30,1985gfAttactIaacc:4.J.M.Cleveland(AEP)Nr.M.P.Alexich(AEP)Hr.G.John(AEP)Mr.H.G.Shaw(ENC)Mr.R.A.Copeland(KNC)r.R.L.Heiks(ENC)understandingthattheENCfuelinO.C.CookUnit1isnotintheexposurerangeforwhichthiscalculationisapplicable.Sincerely,J.S.Holm,ManagerPNSafetyAnalysisRAPID<go..<<~7PAGE~,Oag Table1O.C.CookUnit1ErrorinTOOOEE2Input;RodRadialPowerDistributionseOescritioneviousResult*PeakCladTemperatureOF1827CrrectedResultwithincreasedpelletdensityandreducedfuelrhdpressurel2189III*Thepreviousresultwasforacosinepowerdistributionat48,0NMD/kgexposure,Fq*l.82,reportedinReferences1and2.