ML17264B144

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LER 97-007-00:on 971117,NF Low Range Trip Circuitry for Channel N-44 Was Not Placed in Tripped Condition.Caused by Technical Inadequacies in Procedures.Implemented EWR 4862 to Resolve Design deficiency.W/971217 Ltr
ML17264B144
Person / Time
Site: Ginna Constellation icon.png
Issue date: 12/17/1997
From: MECREDY R C, ST MARTIN J T
ROCHESTER GAS & ELECTRIC CORP.
To: VISSING G S
NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-97-007, LER-97-7, NUDOCS 9712300101
Download: ML17264B144 (14)


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CATEGORY1REGULARYINFORMATIONDISTRIBUTISYSTEM(RZDS)ACCESSIONNBR:9712300101DOC.DATE:97/12/17NOTARIZED:NODOCKET¹FACIL:50-244RobertEmmetGinnaNuclearPlant,Unit1,RochesterG05000244AUTH.NAMEAUTHORAFFILIATIONSTMARTIN,J.T.RochesterGas&ElectricCorp.MECREDY,R.C.RochesterGas&ElectricCorp.RECIP;NAMERECIPIENTAFFILIATIONVISSING,G.S.

SUBJECT:

LER97-007-00:on971117,NFlowrangetripcircuitryforchannelN-44wasnotplacedintrippedcondition.Causedbytechnicalinadequaciesinprocedures&.designdeficiency.EWR4862implementedtoresolvedesigndeficiency.W/971217ltr.DZSTRZBDTZONCODE:ZE22TCOPZESRECEZVED:LTRIENCLiS1ZE:TITLE:50.73/50.9LicenseeEventReport(LER),IncidentRpt,etc.NOTES:LicenseExpdatein.accordancewith10CFR2,2.109(9/19/72).050002440RECIPIENTIDCODE/NAMEPD1-1PDINTERNAL:AEODSD.RABLECEEEELBNRR/DRCH/HHFBNRR/DRCH/HOLBNRR/DRPM/PECBNRR/DSSA/SRXBRGN1FILE01COPIESLTTRENCL112~211111111111111RECIPIENTIDCODE/NAMEVISSZNG,G.AEOD/SPD/RRABNRR/DE/ECGBNRR/DE/EMEBNRR/DRCH/HICBNRR/DRCH/HQMBNRR/DSSA/SPLBRES/DET/EIBCOPIESLTTRENCL1111111111111111DEXTERNAL:LSTLOBBYWARDNOACPOORE,W.NRCPDR111111LITCOBRYCE,JHNOACQUEENER,DSNUDOCSFULLTXT111111UENOTETOALL"RIDS"RECIPIENTS:PLEASEHELPUSTOREDUCEWASTE.TOHAVEYOURNAMEORORGANIZATIONREMOVEDFROMDISTRIBUTIONLISTSORREDUCETHENUMBEROFCOPIESRECEIVEDBYYOUORYOURORGANIZATION,CONTACTTHEDOCUMENTCONTROLDESK(DCD)ONEXTENSION415-2083FULLTEXTCONVERSIONREQUIREDTOTALNUMBEROFCOPIESREQUIRED:LTTR24ENCL24 AenROCHESTfRGASAADE.'ECTRiC'rGRATIOIV~B9E4STAVENUFROC,E'NV,r'l6d9'OOOI~t~'3DEFI6S".6Z'XROBERTC.MECREDYVicePresidenthec.'ecrCerconsDecember17,1997U.S.NuclearRegulatoryCommissionDocumentControlDeskAttn:GuyS.VissingProjectDirectorateI-1Washington,D.C.20555

Subject:

LER97-007,ReactorTripInstrumentationWouldHaveBeeninaConditionProhibitedbyTechnicalSpecificationsR.E.GinnaNuclearPowerPlantDocketNo.50-244

DearMr.Vissing:

Inaccordancewith10CFR50.73,LicenseeEventReportSystem,item(a)(2)(i)(B),whichrequiresareportof,"Anyoperationorconditionprohibitedbytheplant'sTechnicalSpecifications",theattachedLicenseeEventReportLER97-007isherebysubmitted.Thiseventhasinnowayaffectedthepublic'shealthandsafety.Verytrulyyours,RobertC.MecredI/r'r'~sJxc:Mr.GuyS.Vissing(MailStop14B2)ProjectDirectorateI-1DivisionofReactorProjects-I/IIOfficeofNuclearReactorRegulationU.S.NuclearRegulatoryCommissionWashington,D.C.20555RegionalAdministrator,RegionIU.S.NuclearRegulatoryCommission475AllendaleRoadKingofPrussia,PA19406'Q.g.PQCGinnaSeniorResidentInspector*97i23OO05000244PDRADOCK8ItIIIIIIIIIIIIIIIIIII/gf 0

NRCFORM366(4-95)U.S.NUCLEARREGULATORYCOMMISSIOLICENSEEEVENTREPORT(LER),(Seereverseforrequirednumberofdigits/charactersforeachblock)APPROVEDBYOMBNO.3150-0104EXPIRES04/30/96ESTIMATEDBURDENPERRESPONSEToCOMPLYWITHTHISMANDATORYINFORMATIONCOLLEClloNREQUEST:50.0HRS.REPORTEDLESSONSLEARNEDAREINCORPORATEDINTOTHELICENSINGPROCESSANDFEDBACKToINDUSTRY.FORWARDCOMMENTSREGARDINGBURDENESTIMATEToTHEINFORMATIONANDRECORDSMANAGEMENTBRANCH(T-6F33),U.S.NUCLEARREGULATORYCOMMISSION,WASHINGTON,DC20555-0001,ANDToTHEPAPERWORKREDUCTIONPROJECTFACIUTYNAMEI1)R.E.GinnaNuclearPowerPlantDOCKETNUMBER(2105000244PACEI3)1OF7TITLEI4)ReactorTripInstrumentationWouldHaveBeeninaConditionProhibitedbyTechnicalSpecificationsEVENTDATE(5)MONTHDAYYEARLERNUMBER(6)SEQUENTIALREVISIONNUMBERNUMBERMONTHDAYYEARREPORTDATE(7)FACILITYNAMEOTHERFACILITIESINVOLVED(6)DOCKETNUMBER11179797-007-00121797FACILITYNAMEDOCKETNVM8EROPERATINGMODE(9)POWERLEVEL(10)NAME00020.2201(b)20.2203(a)(1)20.2203(a)(2)(i)20.2203(a)(2)(ii)20.2203(a)(2)(iii)20.2203(a)(2)(iv)20.2203(a)(2)(v)20.2203(a)(3)(I)20.2203(a)(3)lii)20.2203(a)(4)50.36(c)(1)50.36(c)(2)X50.73(a)(2)(i)50.73(a)(2)(ii)50.73(a)(2)(iii)50.73(a)(2)(iv)50.73(a)l2)(v)SO.73(a)(2)(vii)50.73(a)(2)(viii)50.73(a)(2)(x)73.71OTHERSpecrfvInAbstractbeloworinNRCFerro366ALICENSEECONTACTFORTHISLER(12)TELEPHONENUMBER(InerrreeAreaCode)THISREPORTISSUBMITTEDPURSUANTTOTHEREQUIREMENTSOF10CFRE:(Checkoneormoro)l11)JohnT.St.Martin-TechnicalAssistant(716)771-3641COMPLETEONELINEFOREACHCOMPONENTFAILUREDESCRIBEDINTHISREPORT(13)CAUSESYSTEMCOMPONENTMANUFACTURERToNPRDSCAUSESYSTEMCOMPONENTMANUFACTURERREPORTABLETONPRDSSUPPLEMENTALREPORTEXPECTED(14)YES(Ifyes,completeEXPECTEDSUBMISSIONDATE).XNOEXPECTEDSUBMISSIONDATE(15)MONTHDAYYEARABSTRACT(Limitto1400spaces,i.e.,approximately15single-spacedtypewrittenlines)(16)OnNovember17,1997,theplantwasinMode3withareactorcoolantsystemheatupinprogress.OnenuclearinstrumentationsystempowerrangechannelwasremovedfromserviceinpreparationforthebeginningofCycle27physicstesting.Thereactorengineerrecognizedthattheneutronfluxlowrangetripcircuitryforthischannelwasnotinthetrippedcondition,asrequiredpriortoentryintoMode2.Sincetheplantwasnotinamodewherethepowerrangesarerequiredtobeoperable,noimmediatecorrectiveactionwasrequired.SubsequenttotheNovember17condition,researchintothesystemdesignandoperatinghistoryshowedthat,priorto1988,theneutronfluxhighrangetripcircuitrywasnotroutinelyplacedinthetrippedconditionduringchanneldefeats.-Theunderlyingcausewastechnicalinadequaciesinproceduresanddesigndeficiency,inthatInstrumentandControlproceduresutilizedforchanneldefeatdidnotaddresstheneedforneutronfluxlowrangetripcircuitrytobeinthetrippedcondition,andtheoriginalplantdesignrequiredliftingleadstoplacetheneutronfluxhighrangetripcircuitryinthetrippedcondition.WhilethisconditionisnotreportablefortheNovember17,1997,condition,thisconditionwouldhaveoccurredduringphysicstestingperformedinthepast,andwasnotrecognizedatthosetimes.Atthosetimes,theplantwouldhavebeeninaconditionprohibitedbytheTechnicalSpecifications.CorrectiveactiontopreventrecurrenceisoutlinedinSectionV.B.NRCFORM366(4.95)

NRCFORM366A(4-95)LICENSEEEVENTREPORT(LER)TEXTCONTINUATIONU.S.NUCLEARREGULATORYCOMMISSIONFACILITYNAME(1)R.E.GinnaNuclearPowerPlantDOCKET05000244LERNUMBER(6)YEARSEQUENTIALREVISIONNUMBERNUMBER97-007-00PAGE(3)2OF7TEXT(Ifmorespeceisrequired,useedditionelcopiesofNRCForm386Ai(17)PRE-EVENTPLANTCONDITIONS:OnNovember17,1997,theplantwasinMode3withthereactortripbreakersopenandareactorcoolantsystem(RCS)heatupinprogress.RCStemperaturewasbeingincreasedfrom350degreesFtogreaterthan540degreesFandpressurizer(PRZR)pressurewasbeingincreasedfromlessthan1000PSIGto2235PSIG(normalconditionsforMode2).InstrumentandControl(ISC)personnelhaddefeatedonenuclearinstrumentationsystem(NIS)powerrange(PR)channel(channelN-44)toallowitsdetectorstobeconnectedtoareactivitycomputerduringreactorstartupandCycle27physicstesting.II.DESCRIPTIONOFEVENT:A.DATESANDAPPROXIMATETIMESOFMAJOROCCURRENCES:June9,1996(andothertimes):Physicstestingduringpreviousplantoutageswithneutronfluxtripcircuitrynotinthetrippedcondition.Estimatedeventdates.November17,1997,1152EST:Discoverydateandtime.EVENT:OnNovember17,1997,atapproximately1152EST,afterthedefeatofNISPRchannelN-44,aMainControlBoardwalkdownwasconductedbythereactorengineer.Duringthiswalkdown,herecognizedthattheNC44Pbistablelight,forneutronfluxlowrangetrip(NFLRT)circuitry,wasnotilluminated.Thus,itwasnotinthetrippedcondition.AninvestigationwasconductedanditwasconfirmedthattheNFLRTcircuitryforchannelN-44wasnotplacedinthetrippedcondition,asrequiredbytheGinnaStationImprovedTechnicalSpecifications(ITS),LimitingConditionforOperation(LCO)REQUIREDACTION3.3.1.D.1(whichisapplicableforonlyModes1and2).SincetheplantwasinMode3atthetimeofdiscovery,andtheNFLRTfunctionisnotrequiredtobeoperableinMode3,theplantwasincompliancewiththeITS.AtestcurrentsignalwassimulatedintheN-44channeltoplacethechannel'sNFLRTcircuitryinthetrippedcondition.ThisensuredcompliancewithITSLCO3.3.1forsubsequententryintoMode2,wherethisLCOwasapplicable.Investigationofthisevent,andresearchintothesystemdesignandoperatinghistoryshowed:~TheIRCprocedureusedforthedefeatofNISPRchannelN-44wasspecifiedasapplicableinallplantmodes.Theprocedurewasdeficient,sinceitdidnotensurethattheNFLRTcircuitrywasplacedinatrippedconditionwhenintheITSmodesofapplicability(Mode2andwheninMode1withthermalpower(6%)asspecifiedinITSTable3.3.1-1,Function2.b.NRCFORM366A(4-95)

NRCFORM366A(4-95)LZCENSEEEVENTREPORT(LER)TEXTCONTINUATIONU.S.NUCLEARREGULATORYCOMMISSIONFACILITYNAME(1IR.E.GinnaNuclearPowerPlantDOCKET05000244PAGE(3ILERNUMBER(6)YEARSEQUENTIALREVISIONNUMBERNUMBER3OF797-007-00TEXTIifmorespeceisrequired,useeddidonelcopiesofNRCForm368AI(17)~ThisconditiondidnotapplytotheNISPRneutronfluxhighrangetrip(NFHRT)circuitryin1997,becausetheNFHRTcircuitryhadbeenmodifiedin1990.Thisearliermodification,performedunderEngineeringWorkRequest(EWR)4862,installedtwo-position(OT-2)switchesthatpermittedmaintainingtheaffectedNFHRTcircuitryinthetrippedcondition.However,aspartoftheinvestigationandresearchforthisLER,itwasdiscoveredthatpriorto1988,therewereinstanceswhenitispresumedthattheNFHRTcircuitryhadnotbeenplacedinatrippedconditionbyapplicableIRCprocedures.Thus,frominitialplantstartupuntil1988,theplantwouldnothavebeenincompliancewiththeoriginalGinnaStationTechnicalSpecificationsatthosetimeswhenanNISPRchannelwouldhavebeenrequiredtobedefeatedwithappropriateneutronfluxtripcircuitryinthetrippedcondition.AsperTechnicalSpecificationsineffectatthosetimes,theNISPRNFHRTisrequiredtobeoperableforall4channels"whenRCCAiswithdrawn".Notethat"RCCA"standsfor"rodclustercontrolassembly".Anytime(includingphysicstesting)priorto1988whenaNISPRchannelwasremovedfromserviceutilizingIRCprocedures(whenRCCAwaswithdrawn),itisnowpresumedthatthoseactionsdidnotcomplywithTechnicalSpecificationsrequirements.Notethatfrom1988to1990,temporaryprocedurechangesensuredthattheNFHRTcircuitrywastrippedbyliftingtwoleads.AftercompletionofEWR4862(from1990tothepresent),theNFHRTcircuitryisnowtrippedbyuseofatwo-positionOT-2switch.C.INOPERABLESTRUCTURES,COMPONENTS,ORSYSTEMSTHATCONTRIBUTEDTOTHEEVENT:NoneD.OTHERSYSTEMSORSECONDARYFUNCTIONSAFFECTED:NoneE.METHODOFDISCOVERY:Duringtheresearchconductedbyplantstaff,itbecameapparentthateventhoughthecurrentITSwerecompliedwithduringthisevolutionin1997,inthepasttheplantwouldhavebeeninaconditionprohibitedbyTechnicalSpecificationsatspecifictimes.F.OPERATORACTION'incetheplantwasincompliancewithITSatthetimeofdiscovery,nooperatoractionswererequired.NRCFORM366A(4.95) 0 NRCFORM366A(4-95)LICENSEEEVENTREPORT(LER)TEXTCONTINUATION.S.NUCLEARREGULATORYCOMMISSIONFACILITYNAME(1)R.E.GinnaNuclearPowerPlantDOCKET05000244LERNUMBER(6)YEARSEQUENTIALREVISIONNUMBERNUMBER97-007-00PAGE(3)4OF7TEXTIifmorespaceisrequired,useadditionalcopiesofNRCForm366AI(17)G.SAFETYSYSTEMRESPONSES:NoneIII.CAUSEOFEVENT:A.IMMEDIATECAUSE:TheimmediatecauseofbeinginaconditionprohibitedbyTechnicalSpecificationswouldhavebeenfailuretoplaceNISPRneutronfluxtripcircuitryintoatrippedconditionatthetimesrequiredbytheTechnicalSpecifications.FortheNISPRNFLRTcircuitry,thiscouldhaveoccurredduringpastplantstartupsfromrefuelingoutages,whenchannelN-44wasdefeatedforphysicstesting.ThiscouldhavealsooccurredifanyNISPRchannelhadbeenremovedfromserviceutilizingI&CproceduresduringMode2orduringMode1andthermalpower<6%.EventscouldhaveoccurredfrominitialplantstartupuntilJune9,1996(thedateoftheCycle26physicstesting).FortheNISPRNFHRTcircuitry,thisalsocouldhaveoccurredifanyNISPRchannelhadbeenremovedfromserviceutilizingI&Cprocedures"whenRCCAiswithdrawn"frominitialplantstartupuntil1988.B.INTERMEDIATECAUSE:TheintermediatecauseofnotplacingNISPRneutronfluxtripcircuitryintoatrippedconditionwhenrequiredisduetotechnicalinaccuraciesinwrittenprocedures,inthatthel&CproceduresutilizedtodefeataNISPRchanneldidnotensureneutronfluxtripcircuitrywasinatrippedcondition,andproceduresusedtodocumenttheinoperabilityofNISPRchannelsdidnotensurecompliancewithITSrequirements.ROOTCAUSE:Underlyingcausesforthetechnicalinaccuraciesinproceduresinclude:InterfaceDesign,inthattheuniquenessoftheoriginaldesignforplacingneutronfluxtripcircuitryintoatrippedconditionwasnotemphasized.NRCFORM366A(4-95)

NRCFORM366A(4-95)LICENSEEEVENTREPORT(LER)TEXTCONTINUATIONU.S.NUCLEARREGULATORYCOMMISSIONFACILITYNAME(1)R.E.GinnaNuclearPowerPlantDOCKET05000244LERNUMBER(6)YEARSEQUENTIALREVISIONNUMBERNUMBER97-007-00PAGE(3)5OF7TEXTllfmorespeceisrequired,useedditionelcopiesofNRCFormM6A/(17)ChangeManagement,inthattheuniquenessoftheoriginaldesignwasrecognizedduringimplementationofEWR4862.ThePRNFLRTcircuitrymaybeplacedinthetrippedconditionbyuseofa"barrel"switch.Theuniqueaspectsofthisbarrelswitchwererecognizedbythedesignengineerandaddressedatthattime,butthisinformationwasnotadequatelyincorporatedintoplantknowledgeandprocedures.Change-relatedtrainingwasnotadequate,andprocedureswerenotrevisedatthattime.DesignConfigurationandAnalysis,inthattheoriginalplantdesignwasdeficient.Theassociatedswitchesweredesignedforreactortriplogictesting,andnotforchanneldefeat.Priorto1990,properdefeatrequiredthatleadsbeliftedtoensurethePRNFHRTcircuitrywasplacedinthetrippedcondition.Training,inthattherewasnotsufficientunderstandingoftheneedtoplaceaffectedtripcircuitryintoatrippedconditionwhendefeatingachannel,andinsufficientawarenessofavailablemethodsfortrippingandverifyingtrippingwasaccomplished.IV.ANALYSISOFEVENT:Thiseventisreportableinaccordancewith10CFR50.73,LicenseeEventReportSystem,item(a)(2)(i)(B),whichrequiresareportof,"Anyoperationorconditionprohibitedbytheplant'sTechnicalSpecifications".ItispostulatedthatITSLCOREQUIREDACTION3.3.1.D.1wasnotperformedduringthescheduledphysicstestingofJune9,1996.PriortotheimplementationoftheITSonFebruary24,1996,itispostulatedthattheoriginalTechnicalSpecifications,Section3.5.1.1,werenotproperlyperformedduringpreviousphysicstestingandatvariousothertimesfrominitialplantstartupuntil1996.Anassessmentwasperformedconsideringboththesafetyconsequencesandimplicationsofthiseventwiththefollowingresultsandconclusions:TherewerenooperationalorsafetyconsequencesorimplicationsattributedtonotplacingaNISPRneutronfluxtripcircuitryintoatrippedconditionbecause:AsdescribedintheITSbasis,thePowerRangeNeutronFluxTripFunctionensuresthatprotectionisprovidedagainstanuncontrolledRCCAbankrodwithdrawalaccident.Therefore,theactuationlogicmustbeabletowithstandaninputfailuretothecontrolsystem,whichmaythenrequiretheprotectionfunctionactuation,andasinglefailureintheotherchannelsprovidingtheprotectionfunctionactuation.AsdescribedintheITSbasis,thePowerRangeNeutronFlux-LowTripFunctionensuresthatprotectionisprovidedagainstapositivereactivityexcursionfromlowpowerorsubcriticalconditions.NRCFORM366A(4-95)

NRCFORM366AI'4-95)LICENSEEEVENTREPORT(LER)TEXTCONTINUATIONU.S.NUCLEARREGULATORYCOMMISSIONFACILITYNAMEI1)R.E.GinnaNuclearPowerPlantDOCKET05000244LERNUMBER(6)YEARSEQUENTIALREVISIONNUMBERNUMBER97-007-00PAGEI3)6OF7TEXTilfmorespaceisrequired,useadditionalcopiesofNRCForm366AI(17)~WithoneNISPRchannelimproperlydefeated,therewouldstillbe3availablechannelswitha2outof3logicrequiredtoactuatetheneutronfluxtripfunction.Therefore,anassumedsinglefailurewouldnotpreventthistripfromactuatingasdesigned.Theintermediaterange(IR)channelreactortrip(whichisabackuptothePRNFLRT)wasunaffectedbythisconditionandwouldalsohavebeenavailabletomitigateareactivitytransientatlowpower(1/2channels).ForinitialstartupsitisthestandardpracticethattheNISPRNFHRTsetpointbeloweredfromitsnormalsetpointof108%to50%power.ThisreductioninsetpointprovidesanadditionalbackuptotheNFLRT.NotetheNFHRTisproperlydefeatedbyCPI-AXIAL-N44.Basedontheabove,itcanbeconcludedthatthepublic'shealthandsafetywasassuredatalltimes.V.CORRECTIVEACTION:A.ACTIONTAKENTORETURNAFFECTEDSYSTEMSTOPRE-EVENTNORMALSTATUS:Nonerequired.B.ACTIONTAKENORPLANNEDTOPREVENTRECURRENCE:~EWR4862wasimplemented,whichresolvedthedesigndeficiencyfortheNISPRNFHRTcircuitry.~ProceduresCPI-AXIAL-N-41/42/43/44andCPI-BISTABLE-N41/42/43/44willbereviewed,andrevisedasnecessary,toensureproperdefeatofneutronfluxtripcircuitry.Notethatoperationsprocedureswillnotbechanged,sincetheyaccomplishproperdefeat,includingplacingrequiredtripcircuitryinthetrippedcondition.~Thedesignandoperationofthebarrelswitch,whichisavailabletoplaceaPRNFLRTcircuitinatrippedcondition,willbethesubjectoffuturetrainingforIRC,operations,andotherappropriatepersonnel.ThisissuewasnotreportedtotheNRCwheninitiallydiscoveredin1988.In1998,administrativeprocessesforidentifyingandreviewingadverseconditionsweredeficient.Thiswasrecognized,andtheACTIONreportingprocesswasimplemented.TheACTIONprocessensuresthatsuchissuesareproperlyevaluatedforNRCreportability.NRCFORM366A(4-95)

NRCFORM366A(4.95)LICENSEEEVENTREPORT(LER)TEXTCONTINUATIONU.S.NUCLEARREGULATORYCOMMISSIONFACILITYNAMEI1)DOCKETLERNUMBER(6)PAGEI3)R.E.GinnaNuclearPowerPlant05000244YEARSEQUENTIALREVISIONNUMBERNUMBER7OF797-007-00TEXT(Ifmorespeceisrequired,useedditionelcopiesoffVRCForm866AII17)DeficienciesinChangeManagementthatoccurredwithEWR4862havebeencorrected.Organizationalchangeshavecombinedgroupsovertheinterveningyears.Thesechangeshavestreamlinedandenhancedinteractionsandcommunications.AppropriateindicationstoverifyproperNISPRchanneldefeatwillbeidentified.Theneedtoenhanceaffectedprocedureswillbeevaluated.VI.ADDITIONALINFORMATION'.FAILEDCOMPONENTS:None8.PREVIOUSLERsONSIMILAREVENTS:AsimilarLEReventhistoricalsearchwasconductedwiththefollowingresults:NodocumentationofsimilarLEReventswiththesamerootcauseatGinnaStationcouldbeidentified.C.SPECIALCOMMENTS:FortheoriginalGinnaStationTechnicalSpecifications(effectiveuntilFebruary24,1996),4channelsofNuclearFluxPowerRangelowsettingwererequiredtobeoperable"whenRCCAiswithdrawn"andcouldbebypassedwhen"2of4powerrangechannelsgreaterthan10%F.P.".(NuclearFluxPowerRangehighsettingwasrequiredatalltimeswhenRCCAiswithdrawn).Theactionstatementwas:"WiththenumberofoperablechannelsonelessthantheTotalNumberofChannels,operationmayproceedprovidedtheinoperablechannelisplacedinthetrippedcondition..."ForthecurrentITS,4channelsofPowerRangeNuetronFluxlowrangetripfunctionarerequiredtobeoperablewheninMode1withthermalpower(6%orinMode2.TheRequiredActionistoplacetheinoperablechannelintripwithin6hoursorbeinMode3withinanadditional6hours.NRCFORM366AI4-95)

A