ML17228A158

LER 93-004-00:on 930409,typo Discovered in Rept Used to Determine RPS Low RCS Flow Trip Setpoint.Error Existed Since Aug 1988.Caused by Design Control Inadequacy.Engineering Package Developed to Correct calculations.W/930510 Ltr

ML17228A158
Person / Time
Site:	Saint Lucie
Issue date:	05/10/1993
From:	SAGER D A, YOUNG R J FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-93-129, LER-93-004-02, LER-93-4-2, NUDOCS 9305180328
Download: ML17228A158 (7)

Text

ACCELERANTDOCUMENTDISTRj:UTIONSYSTEMREGULATINFORMATIONDISTRIBUTIONSTEM(RIDS)ACCESSIONNBR:9305180328DOC.DATE:93/05/10NOTARIZED:NOFACIL:50-335St.LuciePlant,Unit1,FloridaPower&LightCo.AUTH.NAMEAUTHORAFFILIATIONYOUNG,R.J.FloridaPower&LightCo.SAGER,D.A.FloridaPower&LightCo.RECIP.NAMERECIPIENTAFFILIATIONDOCKET¹05000335

SUBJECT:

LER93-004-00:on930409,typodiscoveredinreptusedtodetermineRPSlowRCSflowtripsetpoint.ErrorexistedsinceAug1988.Causedbydesigncontrolinadequacy.Engineeringpackagedevelopedtocorrectcalculations.W/930510ltr.DZSTRZSUTZONCODE:IE22TCOPIESRECEIVED:LTRIENCL/SIZE:TITIE:50.73/50.9LicenseeEventReport(LER),IncidentRpt,etc.NOTES:DRECIPIENTIDCODE/NAMEPD2-2LANORRISgJINTERNAL:ACNWAEOD/DOAAEOD/ROAB/DSPNRR/DE/EMEBNRR/DRCH/HHFBNRR/DRCH/HOLBNRR/DRSS/PRPBNRR/DSSA/SRXBRES/DSIR/EIBEXTERNAL:EG&GBRYCEPJ.HNRCPDRNSICPOOREPW.COPIESLTTRENCL1111221122111111221111221111RECIPIENTIDCODE/NAMEPD2-2PDACRSAEOD/DSP/TPABNRR/DE/EELBNRR/DORS/OEABNRR/DRCH/HICBNRR/DRIL/RPEBNRR.DSSA/SPLB02RGN2FILE01LSTLOBBYWARDNSICMURPHY,G.ANUDOCSFULLTXTCOPIESLTTRENCL11221111111,111111111111.111DDDDNOTETOALL"RIDS"RECIPIENTS:PLEASEHELPUSTOREDUCEWASTE!CONTACTTHEDOCUMENTCONTROLDESK,ROOMPl-37(EXT.504-2065)TOELIMINATEYOURNAMEFROMDISTRIBUTIONLISTSFORDOCUMENTSYOUDON'TNEED!DFULLTEXTCONVERSIONREQUIREDTOTALNUMBEROFCOPIESREQUIRED:LTTR32ENCL32 PP'fMay10,1993L-93-12910CFR50.73U.S.NuclearRegulatoryCommissionAttn:DocumentControlDeskWashington,D.C.20555Re:.St.LucieUnit1DocketNo.50-335ReportableEvent:93-004DateofEvent:April9,1993IncorrectRCSLowFlowTripSetpointduetoaDesinErrorTheattachedLicenseeEventReportisbeingsubmittedpursuanttotherequirementsof10CFR50.73toprovidenotificationofthesubjectevent.Verytrulyyours,4A8a~D.A.gerVicersidentSt.LuePlantDAS/JWH/kwAttachmentcc:StewartD.Ebneter,RegionalAdministrator,USNRCRegionIISeniorResidentInspector,USNRC,St.LuciePlantDAS/PSL8917-931700339305i803289305i0PDRADOCK05000335SPDRanFPLGroupcompany PPPFPLFEOElmloolNRCFormK6(M9)L.S.tEUCLEARREGULATORYCOMMISSIONLICENSEEEVENTREPORT(LER)APPROYOTONENCk0110010IENNPEE'NHNTEETPIATE0NAaENPENINEPCNTETOCEPNCYWITHTI00NfOIEAATlONCCATECSTINTINCEEET.>>0HTESONWNaCONNENTESNONEPNOTAfaENEETTwIEToTHEINOCla0ANTPEPONTENANAKINNTEAANCHTPANIAIANIANAENIPEIANATCNY~WATPNarol.OCIPHENaToTHEPPENWITTNSEOOCTONPNOECTo'110010PACfSCEOfNAMOEIENTPIEIOAXNT.WASPNeOTCPCOCITNELFACILITYNAME(1)St.LucieUnit1DOCKETNUMBER(2)PAGE305000335104(4)IncorrectReactorCoolantSystemLowFlowTripSetpointresultsinaconditionprohibitedbyTechnicalSpecificationsduetoaDesignControlInadequacy.EVENTDATE(5)LERNUMBER(6)REPORTDATE(7)OTHERFACILITIESINVOLVED(8)MOMlHDAY0409OPERATINGMODE(9)YEARYEAR9393SIAL004MONTHDAYYEAR00051093FACILITYNAMESN/AN/A20.402(b)20.405(c)50.73(a)(2)(iv)THISREPORTISSUBMITTEDPURSUANTTOTHEREQUIREMENTSOF10CFR:Checkoneormoreofthefollowin(11)DOCKETNUMBER(S)050000500073.71(b)POWERLEVEL(10)20.405(a)(1)(i)20.405(a)(1)(ii)20.405(a)(1)(iii)20.405(a)(1)(iv)20.405(a)(1)(v)50.36(c)(1)50.36(c)(2)50.73(a)(2)(i)50.73(a)(2)(ii)50.73(a)(2)(iii)50.73(a)(2)(v)50.73(a)(2)(vii)50.73(a)(2)(viii)(A)50.73(a)(2)(viii)(B)50.73(a)(2)(x)73.71(c)OTHER(SpecifyinAbstractbelowandinTextNRCForm366A)NAMELICENSEECONTACTFORTHISLER12RobertJ.Young,ShiftTechnicalAdvisorTELEPONENUMBERAREACODE407465.3550COMPLETEONELINEFOREACHCOMPONENTFAILUREDESCRIBEDINTHISREPORT13CAUSESYSTEMCOMPONENTMANUFAG-REPORTABLETURERTONPRDSCAUSESYSTEMCOMPONENTMANUFAC-REPORTABLElURERTONPRDSSUPPLEMENTALREPORTEXPECTED14IIIEXPECTEDMONIHDAYYEARSUBMISSIONDATE(15)YES(Ifyes,completeEXPECTEDSUBMISSIONDATE)ABSTRACT(Limitto1400spaces.ie.approximatelyfifteensingle-spacetypewrittenlines)(16)OnApril9,1993,St.LucieUnit1wasinMode6whenatypographicalerrorwasdiscoveredbyFPLNuclearEngineeringinareportusedtodeterminetheReactorProtectionSystem(RPS)lowReactorCoolantSystem(RCS)flowtripsetpoint.TechnicalSpecification2.2.1,Table2.2-1statesthatthetripsetpointwillbegreaterthanorequalto95%ofdesignreactorcoolantflow.TheFPLNuclearEngineeringreport,whichdescribedtheconversionofpressuredropacrossthesteamgeneratorstotheRPSlowRCSflowtripsetpoint,containedanincorrectconstant.ThereportwassubsequentlytransmittedtotheplantstaffandtheInstrumentandControlDepartmentadjustedtheRCSlowflowsetpoint.ThiserrorcausedthesettingoftheRCSlowflowtripsetpointtoavalueapproximately3%belowtheminimum95%ofdesignflow.ThissetpointerrorexistedsinceAugust1988.Therootcauseofthiseventwasadesigncontrolinadequacy.Atypographicalerrorwasmadeinthereporttransmittedtotheplantstaff.Theerrorwouldhavebeendiscoveredifthereviewprocessforthetransmittedreporthadundergoneanindependentreview.TheNuclearEngineeringprocesscurrentlyinplacepreventsasimilareventfromoccurringbyrequiringindependentreviewoftransmittedsetpoints.Correctiveactionsforthisevent:AnengineeringevaluationwasperformedthatconcludedthattheoperationofUnit1duringthistimeperiodwaswithintheboundsofthesafetyanalysis.AreviewoftheprocedureusedtodeterminetheUnit2lowRCSflowsetpointverifiedthatitdidnotcontainasimilarerror.Afterareviewofinternalrecords,NuclearEngineeringverifiedthatnootherUnit1or2RPSsetpointchangesweretransmittedtotheplantinerror.AnengineeringpackagewasdevelopedtoprovidethecorrectedcalculationsfordeterminationoftheRPSreactorcoolantsystemlowflowtripsetpoint.InstrumentationandControlpersonnelwillreviseappropriateproceduresandinstallthecorrecttripsetpointintheUnit1RPSpriortoenteringmode2.Priortodiscoveryofthisevent,Engineeringadoptedaprocessrequiringindependentreviewofsetpointsbeforetransmittaltotheplantstaff.FPLFacsimileofNRGForm366(6-89)

FPLFsaslnilsofNRCFormSEI(&89)U.S.NUCLEARREGULATORYCOMMISSIONLICENSEEEVENTREPORT(LER)TEXTCONTINUATIONAsswosf0oeIxsssssCIssfxssus'asssfSTAIATf0OATCENsfilINSAONsfToCOINETWITHsissSfCWNATTCNCasEfCOONIfoUECTIsfsIsxsssxswNecoNNENTsIKOANowoEssesNfsoNATEToTIOINcsxsssNeISAONTSNANACEsfNTfssANCHTASTCEuaNXXENTIuauATEXTT~wAEINeTON.OossssfNeToTIOSNEIIwowIsoucwoNTwofcsETIsseIsssasrscfosswNACEISNTNeTseofs.WANNesfsfocssexsFACILITYNAME(1)St.LucieUnit1DOCKETNUMBER(2)YEARLERNUMBER(6)gEQUENTIALNUMBERREVISIONNUMBERPAGE(3)0500033593TEXT(lfmorespaceisrequired,useadditionalNRCForm366A's)(1/)004000204OnApril9,1993,withUnit1inMode6,FPLNuclearEngineeringperformedareviewofthecalculationsthatarecontainedintheSt.LucieUnit1LowFlowTripSetpointCalibrationGuidelines.Thereviewwasbeingperformedtosupportaproposedchangetothesteamgeneratortubepluggingcriteria.Duringthisreview,atypographicalerrorinareportthatdescribedconversionofpressuredropacrosstheSteamGenerators(EIIS:AB)totheReactorProtectionSystem(RPS)(EIIS:JC)ReactorCoolantSystem(RCS)lowflowtripsetpointwasfound.Theerrorresultedinthecalculationofanon-conservativesetpointwithwhichtheRPScreatesanautomaticreactortriptoprotectagainstalossofRCSflow.ThiserrorcausedtheRPSlowRCSflowtripsetpointtobeapproximately3percentbelowtheTechnicalSpecificationminimumof95percentofdesignflow.In1987thereportcontainingtheincorrectinformationwassenttotheplantstafftosupportamodificationtotheRPS.InAugust1988,thereportwasreferencedwhenthemodificationtotheRPSwasimplementedandwasusedtomodifyplantproceduresfortheinitialsettingandsubsequentmonthlychecksofthisRPSlowflowtripsetpoint.ThisconditionwasdiscoveredinAprilof1993.Therootcauseofthiseventwasadesigncontrolinadequacy.AtypographicalerrorwasmadebyFPLNuclearEngineeringinthetransmittalofacalculatedsetpointtotheplantstaff.Duringatransferofinformationfromanindependentlyverifiedengineeringcalculationtoareport,atranscriptionerrorcausedaconstantthatconvertspressuredropacrosstheSteamGeneratorstothelowRCSflowtripsetpointtobenon-conservative.Theincorrectreportwouldhavebeendiscoveredandcorrectedhadthetransmittedreporttotheplantstaffreceivedthesameindependentreviewthattheoriginalcalculationhadreceived.Priortothediscoveryofthisevent,FPLNuclearEngineeringadoptedtheprocessforrequiringindependentreviewofallsetpointsbeforetransmittaltotheplantstaff.Thiseventisreportableunder10CFR50.73(a)(2)(i)(B),as"Anyoperationorconditionprohibitedbytheplant'sTechnicalSpecifications."TechnicalSpecification2.2.1requiresthattheRPStripsetpointforRCSlowflowbesetatorabove95percentofdesignflow(370,000gpm).Forcycles9,10and11ofUnit1operation,theRCSlowflowtripwaserroneouslysetatslightlyhigherthan92percentofdesignflow.TheRCSlowflowtripsetpointensuresthatforadegradationofRCSflowresultingfromanalyzedtransients,areactortripoccurstopreventdeparturefromnucleateboilingratio(DNBR)safetylimits.TheprocesssignalforthisfunctionisdevelopedfromfourindependentdifferentialpressurechannelswhichmeasurethepressuredropacrosstheprimarysideofbothSteamGenerators.ThetotalSteamGeneratorpressuredropiscomparedwiththelowRCSflowtripsetpoint.Iftwochannelsindicateaflowwhichislessthanthetripsetpoint,anRPStripsignalisinitiated.FPLFacsimileofNRCForm366(6-89)

FPLFacstmloolNRCFormS66($89)U.S.NUCLEARREGULATORYCOMMrSSIONUCENSEEEVENTREPORT(LER)TEXTCONTINUATION,AAINorrocooNI$$$$oerorcofrfoarrfoeooeTAIATToofvcrNITNIoefcfocToccoe$vTATNoooofrfvAACONcouococNIacracTl$04IeoafoNwrfoccrrrNTofccfrlooroIAATIENoeoNATcToTtoIocofoowo$fafomoNANACT$CNTONANCNreeTCAuaNOCITANIN$$AATONv~wANNIOTCN,oc$0$$aANITollofATNAwrovrIacucocNffvoacI$$$Ioeror$cffICEofIIANAccoaNTAfo$$$$ccr,wANNrcrcfoocToooaFACILITYNAME(1)St.LucieUnit1DOCKETNUMBER(2)YEARLERNUMBER(6)EQUENTIAL-rREVISIONNUMBER4NUMBERPAGE(3)0500033593TEXT(Ifmorespaceisrequired,useadditionalNRCForm366A's)(17)004000304Anevaluation(JPN-PSL1-SEFJ-93-006)wasperformedbyFPLEngineeringtodeterminetheavailablesafetyanalysismarginforthemostlimitingtransients(lossofoffsitepowerandlossofRCSflow)forwhichprotectionisprovidedbytheRCSlowflowtrip.Theresultsshowthattheapproximate3percentsetpointerrorissufficientlyoffsetbyavailableflowmargin.Thus,violationoftheDNBRlimitforalossofoffsitepoweroralossofRCSfloweventwouldnothaveoccurrediftherehadbeenadegradationofRCSfloweventduringthetimeperiodthatthesetpointerrorwasinplace.(AreviewofUnit1reactortripsshowedthattheRCSlowflowtripfunctionwasnotchallengedduringcycles9,10and11.Anadditionalreviewofactualoperatingconditionsduringcycles9,10,and11wasperformedtoensurethatnootherconditionexistedthatwouldfurtheraggravatetheconditiondescribedinthisLER).TheReactorCoolantPump(RCP)(EIIS:P)seizedrotoreventhasbeenreanalyzedbythefuelvendorfora4percentreductionindesignflowandthecorresponding4percentreductionintheRCSlowflowtripsetpoint.TheanalysisshowsthattheacceptancecriteriaforthepostulatedRCPseizedrotoreventwasnotviolated.Therefore,thehealthandsafetyofthepublicwasnotaffectedbythiscondition.1.Priortothediscoveryofthisevent,NuclearEngineeringproceduralizedareviewprocesstoensuretheaccuracyofsetpointsandplantchanges.Thisprocessrequiresanindependentverificationofsetpointsandplantchangesbeforetransmittaltotheplantstaff,andwouldhavedetectedtheerrordescribedinthisreport.2.NuclearEngineeringpreparedanengineeringevaluationanddeterminedthatoperationofUnit1wasboundedbythesafetyanalysesforCycles9,10,and11.3.NuclearEngineeringreviewedinternalrecordsandverifiedthatnootherUnit1or2RPSsetpointchangesweretransmittedtotheplantstaffinerror.4.NuclearEngineeringreviewedtheUnit2RCSLowFlowTripSetpointDeterminationprocedureandverifiedthatitdidnotuseerroneousdata.5.AFPLengineeringpackagewasdevelopedtodocumentandtransmitthecorrectedcalculationfortheUnit1RPSIowRCSflowtripsetpoint.6.TheI&CDepartmentwillreviseprocedures1-0120050and1-1400050~toreflectthecorrectRCSlowflowtripsetpointspriortoUnit1enteringMode2.7.TheI&CDepartmentwillmaketheRPSlowRCSflowtripsetpointchangespriortoUnit1enteringMode2.FPLFacsimileofNRCForm366(6-89)

FPLF55cslrrlloolNRCFormS6BU.S.NUCLEARREGULATORYCOMMrSSION~LICENSEEEVENTREPORT(LER)TEXTCONTINUATIONAPAN5TITOCAONCI$1500505fAASNS:IO00550TWATToTAANNN05IIINSAONICTOGTANAYWoilTIIS005$0AAOONCOTITCOONISISNST:500ITISICAINNoOONNANT0NTOAIIONOTAAoCNTSTYAATSloTININGTAYISAIAIINICNTSNANAGSISNTSNANCHTNINaIASIANATAIIINGAAATGNY~WANNNTTGN.OG505$5N05TOONAAIYNWCa<ISTACTTGNTNOXGTTITIOSTINTTYNCSTNINNAGSINNTAI05TAOGCT,WAONKITTYAOO5050$.FACILITYNAME(1)DOCKETNUMBER(2)LERNUMBER(6)PAGE(3)St.LucieUnit1YEAR':0500033593EQUENTIALNUMBER004.REVISIONUMBER000404TEXT(Ifmorespaceisrequired,useadditionalNRCForm366A's)(1/)NoneAprevioussimilarLERatSt.LucieinvolvingadesignerrorfortheRPSwas:LER335-79-30SteamGeneratorLowLevelRPStripsetpointslessthanTechnicalSpecificationsduetoadesignermr.FPLFacsimileofNRCForm366(6-89)