ML17331A037

Informs of Plans to Remove Alarming Capabilities of Saturation Margin Monitors in Approx 90 Days,Per Previous Submittals Re NUREG-0578,NUREG-0737 & GL 82-28.Justification for Removal of Alarming Capability Encl

ML17331A037
Person / Time
Site:	Cook
Issue date:	02/12/1993
From:	FITZPATRICK E INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:	MURLEY T E NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
RTR-NUREG-0578, RTR-NUREG-0737, RTR-NUREG-578, RTR-NUREG-737 AEP:NRC:1183, GL-82-28, NUDOCS 9302220199
Download: ML17331A037 (14)

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ACCEIERATO)DOCUMENTDISTRIBUTIONSYSTEMREGULAT~INFORMATIONDISTRIBUTIO~STEM(RIDS)'ACCESSIONNBR:9302220199DOC.DATE:93/02/12NOTARIZED:NODOCKETFACIL:50-315DonaldC.CookNuclearPowerPlant,Unit1,IndianaM0500031550-316DonaldC.CookNuclearPowerPlant,Unit2,IndianaM05000316AUTH.NAMEAUTHORAFFILIATIONFITZPATRICK,E.IndianaMichiganPowerCo.(formerlyIndiana8MichiganEleRECIP.NAMERECIPIENTAFFILIATIONRMURLEYPT.E.DocumentControlBranch(DocumentControlDesk)

SUBJECT:

Informsofplanstoremovealarmingcapabilitiesofsaturationmarginmonitorsinapprox90days,perprevioussubmittalsreNUREG-0578,NUREG-0737aGL82-28.Justification-forremovalofalarmingcapabilityencl.DISTRIBUTIONCODE:A003DCOPIESRECEIVED:LTRrENCL(SIZE:CTITLE:OR/LicensingSubmittal:Suppl1toNUREG-0737(GenericLtr82-33)NOTES:DRECIPIENTIDCODE/NAMEPD3-1LADEANPWINTERNAL:NR~RD~LP/LHFBl1~ILE01EXTERNALPDRCOPIESLTTRENCL1122111111RECIPIENTIDCODE/NAMEPD3-1PDOC/LFMBRES/DSIR/EIBNSICCOPIESLTTRENCL11101111DDSADNOTETOALL"RIDS"RECIPIENTS:PLEASEHELPUSTOREDUCEWASTEICONTACTTHEDOCUMENTCONTROLDESK,ROOMP1-37(EXT.504-2065)TOELIMINATEYOURNAMEFROMDISTRIBUTIONLISTSFORDOCUMENTSYOUDON'TNEED!DTOTAL',NUMBEROFCOPIESREQUIRED:LTTR10ENCL9

~II IndianaMichiganPowerCompanyP.O.Box16631Coiumbus,OH43216AEP:NRC:1183DonaldC.CookNuclearPlantUnits1and2DocketNos.50-315and50-316LicenseNos.DPR-58andDPR-74JUSTIFICATIONFORREMOVALOFTHEB&WSATURATIONMARGINMONITORALARMANDTHEPLANTPROCESSCOMPUTERSATURATIONMARGINMONITORPROGRAMALARMU.S.NuclearRegulatoryCommissionDocumentControlDeskWashington,D.C.20555Attn:T.E.MurleyFebruary12,1993

DearDr.Murley:

InprevioussubmittalsconcerningNUREG-0578,NUREG-0737andGenericLetter82-28,wementionedthatourB&WSaturationMarginMonitorandthePlantProcessComputerSaturationMarginMonitorProgramwouldhavealarmsthatwouldbeannunciatedoncesubcoolingmargindroppedbelow33'F(thesetpointwasrevisedto29'Fin1984).Inthepastfewyears,thesealarmshavebecomeanuisancesincenormalpoweroperationhassomecorelocationswithlessthan29'Fsubcooling.Theyarestandingalarmsandprovidenousefulinformationtothereactoroperators.Thereisnoregulatory,technicalspecification,orUFSARrequirementforthesealarms.Thesestandingalarmscoulddistracttheoperatorsandservenopurpose.Therefore,weintendtoremovethealarmingcapabilityofthesaturationmarginmonitorsinDonaldC.CookUnit1andUnit2inapproximately90days,unlessweareinformedotherwisebyyourstaff.IBOI069302220i999302i2PDRADOCK050003i5IPDR jrt~)~EC Dr.T.E.MurleyPage2AEP:NRC:1183OnFebruary2,1993,amemberofyourstaff,Mr.WilliamM.Dean,andourLicensingSectionManager,Mr.DouglasH.Malin,discussedthepossibilityofremovingtheB&WSaturationMeterAlarmandthePlantProcessComputerSaturationMarginProgramAlarm.Atthattime,Mr.Deanrequestedthatwesubmittothestaffourjustificationforremovingthealarms.AttachmentNumber1tothisletterprovidesthejustificationforremovalofthealarms,asrequestedbyMr.Dean.AttachmentNumber2includestheapplicablecorrespondencewehadwiththestaffconcerningNUREG-0578,NUREG-0737andGenericLetter82-28.Sincerely,E'g~f)E.E.FitzpatrickVicePresidentdrAttachmentsCC:A.A.Blind-BridgmanJ.R.PadgettG.CharnoffA.B.Davis-RegionIIINRCResidentInspector-BridgmanNFEMSectionChief Dr.T.E.MurleyPage3AEP:NRC:1183bc:S.J.BrewerD.H.Malin/K.J.TothM.L.Horvath-BridgmanJ.B.ShinnockW.G.Smith,Jr.W.M.Dean,NRC-Washington,D.C.AEP:NRC:1183DC-N-6015.1 AttachmentNo.1toAEP:NRC:1183JUSTIFICATIONFORREMOVALOFTHEB&WSATURATIONMARGINMONITORALARMANDTHEPLANTPROCESSCOMPUTERSATURATIONMARGINMONITORPROGRAMALARM AttachmentNo.1toAE.C:1183Page1JUSTIFICATIONFORREMOVALOFTHEB&WSATURATIONMARGINMONITORALARMANDTHEPLANTPROCESSCOMPUTERSATURATIONMARGINMONITORPROGRAMALARMINTRDTIAsaresultoftheTMIaccident,NUREG-0587wasissued.TheNUREGprovidedlessonslearnedandshort-termrecommendations.Oneoftherecommendationswastoinstallinstrumentationtomonitorinadequatecorecooling.Oneinstrumentthatwasdeterminedcapableof.providingrelevantinformationwasasaturationmarginmonitor.PriortoJanuary31,1980,asaturationmargincomputerprogramwasinstalledonthePRODAC-250plantprocesscomputer(PPC).Afewmonthslater,adedicateddigitalsaturationmarginmonitor,manufacturedbyBabcockandWilcox(B&W),wasinstalled.Bothofthesaturationmarginmonitorsprovidedalarmingcapabilitiestoalerttheoperatorifsubcoolingofthereactorcoolantsystemdroppedbelowagivensetpoint.Inthepast,thesaturationmarginmonitors'larmshadgivenusonlyafewproblems.Forexample,in1984thesetpointwasrecalculatedandreducedto29'F.Thiskeptthealarmsclearedformanyyears.Withthecurrentconcernsofreactorvesselembrittlement,ourcurrentcoredesignshaveincorporatedlowleakageloadingpatterns(LLLP).AnexpectedresultoftheLLLPwasthatsomefuelassembliesinthecenterofthecorewouldhavehottercoreexittemperatures.OurcurrentUnit2Cycle9coredesignhasafewcoreexittemperaturesyieldingapproximately24'Fmarginofsubcooling.Thus,thecurrentsetpointof29'Fisexceededandthealarmsareannunciated(standingalarm).Torelievetheoperatorsofthestandingalarms,thefollowingoptionshavebeenconsidered:reducethesetpointagain,abandontheLLLPtoachieveamore"flat"powerdistribution,monitoronly"cold"incorethermocouples,orremovethesaturationmarginmonitors'larmingcapability.Themostreasonableoftheseoptionsistoremovethealarmingcapability.Webelievethatsincethealarmscurrentlyprovidetheoperatorwithnousefulinformation,theyshouldberemovedaltogether.Thisisjustifiablesincenocreditistakenforthealarminanyoftheplant'semergencyoperatingprocedures,norisitmentionedintheTechnicalSpecificationsorUFSAR.

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AttachmentNo.1toAE.C:1183Page2BAKR-REATRYAsaresultofNUREG-0578,item2.1.3.b,"InstrumentationforInadequateCoreCooling(SaturationMeter)",severalactionstookplaceatDonaldC.CookNuclearPlanttocomplywiththerecommendations:1.Curvesofsaturationtemperatureversusreactorcoolantpressurewereprovidedtotheoperators.2.AcomputerprogramwaswrittenforthePlantProcessComputer(PPC)tomonitorsaturationmargin.3.Adedicatedsaturationmarginmonitorwasinstalled.Theseactionsweredocumentedinthefollowingsubmittals:AEP:NRC:00334B,March10,1980,AEP:NRC:00334,January18,1980(whichsupplementedthefollowingsubmittals),AEP:NRC:00253C,December26,1979,AEP:NRC:00253B,December19,1979,AEP:NRC:00253A,November26,1979,andAEP:NRC:00253,October24,1979.OnMarch20,1980,thestaffissuedasafetyevaluationreport(SER),referencingtheabovesubmittals,statingthatactions2and3satisfiedtheshorttermlessonslearnedrequirementsforNUREG-0578,item2.1.3.b.InresponsetoGenericLetter82-28,whichreferstoNUREG-0737inregardtosaturationmarginmonitors,wesubmittedtwolettersAEP:NRC:0761,datedMarch11,1983,andAEP:NRC:0761A,datedJune22,1983.OnDecember19,1983,thestaffissuedanSER,withaninitialreviewofourresponses.IntheSER,oursaturationmarginmonitorsweredescribedasfunctionallyacceptable.(ThereasontheSERwasnotfinalwasthatmoreinformationwasrequiredbythestafftocompletetheSER;however,thesaturationmarginmonitorscapabilitieswerenotinquestion).Thesubmittalsreferedtointhe1979/1980timeframemadereferencetothePPCsaturationmarginmonitoralarmingfeatures.TheJune22,1983submittalmadereferencetotheB&WandPPCsaturationmarginmonitoralarmingfeatures.Asstated,informationonthealarmsfeatureswasprovidedtothestaff;however,thesealarmswerenotregulatoryrequirements.Forthestaffsconvenience,thereferencedsubmittalshavebeenincludedinAttachmentNumber2.PleasenotethatintheMarch20,1980SER,afewothersubmittalswerereferenced,buttheyhadnothingtodowiththesaturationmarginmonitor.Therefore,theywerenotincludedinAttachmentNumber2.

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IAttachmentNo.1toAE.C:1183Page3BAKRPERATITHEAATIMARMNITORIn1984,theproblemofstandingalarmsexistedonthesaturationmarginmonitors.Theproblemwaseventuallyresolvedbyrecalculatingthesetpointto29'F.(Thesetpointcalculationisbasedonthemaximumerrorthesaturationmarginmonitorcouldseeduringaccidentconditions.)Thisprovidedadequatemarginuntil1990,whenUnit2Cycle8wasstartedup.Atthattime,wehadswitchedtoanewfuelvendorwhoprovideduswithaLLLP.AsresultoftheLLLP,moreofthereactorpowerwasinthecenterofthecore.Asexpected,thiscausedsomefuelassembliestohavehigherrelativepowers.Thus,creatingsomehottercoreexittemperaturesyieldingsubcoolingmarginsoflessthe29'F,andcausingthesaturationmarginmonitors'tandingalarms.Asmentionedintheintroduction,thefoHowingoptionstoeliminatethestandingalarmwereconsidered:2.3.4.reducethesetpointagain,abandontheLLLPtoachieveamore"flat"powerdistribution,monitoronly"cold"incorethermocouples,andremovethesaturationmarginmonitorsalarmingcapability.Thefirstthreeoptionswererejectedforthefollowingreasons:Reducingthesetpointcouldonlybejustifiedbyourexperience-basedknowledgethattheincorethermocouplesareaccuratetoapproximately+5'F(basedonmeasuredpowerdistributionandcalculatingtheexpectedexittemperatures).However,thesaturationmarginmonitorisforpostaccidentmonitoringandwehavenobasistoremovetheerrortolerancesbuiltintothesetpointforaccidentconditions.2.3.ThebenefitsoftheLLLPforreducingvesselembrittlementoutweighsthebenefitsofhavingthealarmsavailable,forwhichcreditisnottakenandarenotrequired.Monitoringonly"cold"incorethermocoupleswouldonlydefeatthepurposeof'hesaturationmarginmonitor.Duringanaccident,thefirstcorelocationsthatwouldmostlikelylosetheirsaturationmargin,orboil,wouldbetheoneswithfuelassemblieswiththehighestdecayheat.Theseassemblieswouldtypicallybethosewiththehighestcoreexittemperatures.Therefore,monitoring"cold"assemblieswouldnotbeprudent.Thus,theonlyreasonablesolutiontoclearthestandingalarmsistoremovethealarmingcapabilitiesofthesaturationmarginmonitors.

~\C1 0AttachmentNo.1toAE.C:1183Page4REVIEWANTAKETIFIATINUREG-0578,NUREG0737andGenericLetter82-18werereviewedtodetermineifanyrequirementsexistedcommittingustoinstallalarmsonoursaturationmarginmonitors.NUREG-0578andGenericLetter82-18makenostatementsregardingsaturationmarginmonitoralarms.TheonlyreferenceofalarmswasfoundinNUREG-0737.InSectionII.F.2,INSTRUMENTATIONFORDETECTIONOFINADEQUATECORECOOLING,Clarification10,thefollowingisstated:"Thetypesandlocationofdisplaysandalarmsshouldbedeterminedbyperformingahuman-factorsanalysistakingintoconsideration:(a)theuseofthisinformationbyanoperat'orduringbothnormalandabnormalplantconditions,(b)'ntegrationintoemergencyprocedures,(c)integrationintooperatortraining,and(d)otheralarmsduringemergencyandneedforprioritizationofalarms."Clarification10revealsthatNUIT-0737allowedthelicenseetoconsiderwhatwouldprovidethebestinformationofinadequatecorecoolingtotheoperator.Atthetimeweinstalledthesaturationmarginmonitors,thealarmswereaviablemethodforinitiallywarningtheoperatorsofpotentialinadequatecorecooling.Consideringthechangesincoredesignsovertheyears(LLLP),thealarmsassociatedwiththesaturationmarginmonitorsarenolongereffectiveanddonotassisttheoperatorinassessinginadequatecorecooling.Thereasonisthatwehaveastandingalarmduringnormaloperation.Thusfromahuman-factorsstandpoint,theoperatorsarebetterpositionedtoidentifyinadequatecorecoolingbyrelyingonsaturationmarginmonitorreadouts('Fmargin)thanseeinganalarmthatistypicallyannunciating.Infact,intheplant'semergencyoperatingprocedures,nocreditistakenforthealarmsandtheoperatorsareinstructedtochecktheamountofsubcoolingmarginavailablefromtheB&Wsaturationmarginmonitororsafetyparameterdisplaysystem(onthetechnicalsupportcentercomputerdisplayinthecontrolroom).TheUFSARandTechnicalSpecificationswerereviewedforanyreferencetothealarmsonthesaturationmarginmonitors.Thesaturationmarginmonitorsarereferenced,butthealarmsarenotmentioned.NCLUSIONEventhoughthealarmswerediscussedinoursubmittalsconcerninginadequatecorecoolinginstrumentation,therewasnoregulatoryrequirementtoinstallalarmsonsaturationmarginmonitors.Sincethealarmsareonrecordfromourprevioussubmittals,weareprovidingthissubmittalshowingadequatejustificationtoremovebothofthesaturationmarginmonitors'larmingcapabilities.Thiswillbedoneinapproximately90days.Thealarmsareanuisanceandprovidenousefulinformationtothereactoroperator.Thehealthandsafetyofthepublicwillnotbeaffectedbyremovingthesaturationmarginmonitors'larmingcapabilities.