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)

Text

ACCEIERATO)DOCUMENTDISTRIBUTION SYSTEMREGULAT~INFORMATION DISTRIBUTIO~STEM (RIDS)'ACCESSION NBR:9302220199 DOC.DATE:

93/02/12NOTARIZED:

NODOCKETFACIL:50-315 DonaldC.CookNuclearPowerPlant,Unit1,IndianaM0500031550-316DonaldC.CookNuclearPowerPlant,Unit2,IndianaM05000316AUTH.NAMEAUTHORAFFILIATION FITZPATRICK,E.

IndianaMichiganPowerCo.(formerly Indiana8MichiganEleRECIP.NAME RECIPIENT AFFILIATION RMURLEYPT.E.

DocumentControlBranch(Document ControlDesk)

SUBJECT:

Informsofplanstoremovealarmingcapabilities ofsaturation marginmonitorsinapprox90days,perprevioussubmittals reNUREG-0578,NUREG-0737 aGL82-28.Justification-forremovalofalarmingcapability encl.DISTRIBUTION CODE:A003DCOPIESRECEIVED:LTR rENCL(SIZE:CTITLE:OR/Licensing Submittal:

Suppl1toNUREG-0737(Generic Ltr82-33)NOTES:DRECIPIENT IDCODE/NAME PD3-1LADEANPWINTERNAL:

NR~RD~LP/LHFBl1~ILE01EXTERNALPDRCOPIESLTTRENCL1122111111RECIPIENT IDCODE/NAME PD3-1PDOC/LFMBRES/DSIR/EIB NSICCOPIESLTTRENCL11101111DDSADNOTETOALL"RIDS"RECIPIENTS:

PLEASEHELPUSTOREDUCEWASTEICONTACTTHEDOCUMENTCONTROLDESK,ROOMP1-37(EXT.504-2065)

TOELIMINATE YOURNAMEFROMDISTRIBUTION LISTSFORDOCUMENTS YOUDON'TNEED!DTOTAL',NUMBEROFCOPIESREQUIRED:

LTTR10ENCL9

~II IndianaMichiganPowerCompanyP.O.Box16631Coiumbus, OH43216AEP:NRC:1183DonaldC.CookNuclearPlantUnits1and2DocketNos.50-315and50-316LicenseNos.DPR-58andDPR-74JUSTIFICATION FORREMOVALOFTHEB&WSATURATION MARGINMONITORALARMANDTHEPLANTPROCESSCOMPUTERSATURATION MARGINMONITORPROGRAMALARMU.S.NuclearRegulatory Commission DocumentControlDeskWashington, D.C.20555Attn:T.E.MurleyFebruary12,1993

DearDr.Murley:

Inprevioussubmittals concerning NUREG-0578, NUREG-0737 andGenericLetter82-28,wementioned thatourB&WSaturation MarginMonitorandthePlantProcessComputerSaturation MarginMonitorProgramwouldhavealarmsthatwouldbeannunciated oncesubcooling margindroppedbelow33'F(thesetpointwasrevisedto29'Fin1984).Inthepastfewyears,thesealarmshavebecomeanuisancesincenormalpoweroperation hassomecorelocations withlessthan29'Fsubcooling.

Theyarestandingalarmsandprovidenousefulinformation tothereactoroperators.

Thereisnoregulatory, technical specification, orUFSARrequirement forthesealarms.Thesestandingalarmscoulddistracttheoperators andservenopurpose.Therefore, weintendtoremovethealarmingcapability ofthesaturation marginmonitorsinDonaldC.CookUnit1andUnit2inapproximately 90days,unlessweareinformedotherwise byyourstaff.IBOI069302220i99 9302i2PDRADOCK050003i5IPDR jrt~)~EC Dr.T.E.MurleyPage2AEP:NRC:1183 OnFebruary2,1993,amemberofyourstaff,Mr.WilliamM.Dean,andourLicensing SectionManager,Mr.DouglasH.Malin,discussed thepossibility ofremovingtheB&WSaturation MeterAlarmandthePlantProcessComputerSaturation MarginProgramAlarm.Atthattime,Mr.Deanrequested thatwesubmittothestaffourjustification forremovingthealarms.Attachment Number1tothisletterprovidesthejustification forremovalofthealarms,asrequested byMr.Dean.Attachment Number2includestheapplicable correspondence wehadwiththestaffconcerning NUREG-0578, NUREG-0737 andGenericLetter82-28.Sincerely, E'g~f)E.E.Fitzpatrick VicePresident drAttachments CC: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:1183 DC-N-6015.1 Attachment No.1toAEP:NRC:1183 JUSTIFICATION FORREMOVALOFTHEB&WSATURATION MARGINMONITORALARMANDTHEPLANTPROCESSCOMPUTERSATURATION MARGINMONITORPROGRAMALARM Attachment No.1toAE.C:1183Page1JUSTIFICATION FORREMOVALOFTHEB&WSATURATION MARGINMONITORALARMANDTHEPLANTPROCESSCOMPUTERSATURATION MARGINMONITORPROGRAMALARMINTRDTIAsaresultoftheTMIaccident, NUREG-0587 wasissued.TheNUREGprovidedlessonslearnedandshort-term recommendations.

Oneoftherecommendations wastoinstallinstrumentation tomonitorinadequate corecooling.Oneinstrument thatwasdetermined capableof.providing relevantinformation wasasaturation marginmonitor.PriortoJanuary31,1980,asaturation margincomputerprogramwasinstalled onthePRODAC-250 plantprocesscomputer(PPC).Afewmonthslater,adedicated digitalsaturation marginmonitor,manufactured byBabcockandWilcox(B&W),wasinstalled.

Bothofthesaturation marginmonitorsprovidedalarmingcapabilities toalerttheoperatorifsubcooling ofthereactorcoolantsystemdroppedbelowagivensetpoint.Inthepast,thesaturation marginmonitors'larms hadgivenusonlyafewproblems.

Forexample,in1984thesetpointwasrecalculated andreducedto29'F.Thiskeptthealarmsclearedformanyyears.Withthecurrentconcernsofreactorvesselembrittlement, ourcurrentcoredesignshaveincorporated lowleakageloadingpatterns(LLLP).AnexpectedresultoftheLLLPwasthatsomefuelassemblies inthecenterofthecorewouldhavehottercoreexittemperatures.

OurcurrentUnit2Cycle9coredesignhasafewcoreexittemperatures yieldingapproximately 24'Fmarginofsubcooling.

Thus,thecurrentsetpointof29'Fisexceededandthealarmsareannunciated (standing alarm).Torelievetheoperators ofthestandingalarms,thefollowing optionshavebeenconsidered:

reducethesetpointagain,abandontheLLLPtoachieveamore"flat"powerdistribution, monitoronly"cold"incorethermocouples, orremovethesaturation marginmonitors'larming capability.

Themostreasonable oftheseoptionsistoremovethealarmingcapability.

Webelievethatsincethealarmscurrently providetheoperatorwithnousefulinformation, theyshouldberemovedaltogether.

Thisisjustifiable sincenocreditistakenforthealarminanyoftheplant'semergency operating procedures, norisitmentioned intheTechnical Specifications orUFSAR.

~~

Attachment No.1toAE.C:1183Page2BAKR-REATRYAsaresultofNUREG-0578, item2.1.3.b,"Instrumentation forInadequate CoreCooling(Saturation Meter)",severalactionstookplaceatDonaldC.CookNuclearPlanttocomplywiththerecommendations:

1.Curvesofsaturation temperature versusreactorcoolantpressurewereprovidedtotheoperators.

2.AcomputerprogramwaswrittenforthePlantProcessComputer(PPC)tomonitorsaturation margin.3.Adedicated saturation marginmonitorwasinstalled.

Theseactionsweredocumented inthefollowing submittals:

AEP:NRC:00334B, March10,1980,AEP:NRC:00334, January18,1980(whichsupplemented thefollowing submittals),

AEP:NRC:00253C, December26,1979,AEP:NRC:00253B, December19,1979,AEP:NRC:00253A, November26,1979,andAEP:NRC:00253, October24,1979.OnMarch20,1980,thestaffissuedasafetyevaluation report(SER),referencing theabovesubmittals, statingthatactions2and3satisfied theshorttermlessonslearnedrequirements forNUREG-0578, item2.1.3.b.InresponsetoGenericLetter82-28,whichreferstoNUREG-0737 inregardtosaturation marginmonitors, wesubmitted twolettersAEP:NRC:0761, datedMarch11,1983,andAEP:NRC:0761A, datedJune22,1983.OnDecember19,1983,thestaffissuedanSER,withaninitialreviewofourresponses.

IntheSER,oursaturation marginmonitorsweredescribed asfunctionally acceptable.

(ThereasontheSERwasnotfinalwasthatmoreinformation wasrequiredbythestafftocompletetheSER;however,thesaturation marginmonitorscapabilities werenotinquestion).

Thesubmittals referedtointhe1979/1980 timeframemadereference tothePPCsaturation marginmonitoralarmingfeatures.

TheJune22,1983submittal madereference totheB&WandPPCsaturation marginmonitoralarmingfeatures.

Asstated,information onthealarmsfeatureswasprovidedtothestaff;however,thesealarmswerenotregulatory requirements.

Forthestaffsconvenience, thereferenced submittals havebeenincludedinAttachment Number2.PleasenotethatintheMarch20,1980SER,afewothersubmittals werereferenced, buttheyhadnothingtodowiththesaturation marginmonitor.Therefore, theywerenotincludedinAttachment Number2.

fPE'k/

IAttachment No.1toAE.C:1183Page3BAKRPERATITHEAATIMARMNITORIn1984,theproblemofstandingalarmsexistedonthesaturation marginmonitors.

Theproblemwaseventually resolvedbyrecalculating thesetpointto29'F.(Thesetpointcalculation isbasedonthemaximumerrorthesaturation marginmonitorcouldseeduringaccidentconditions.)

Thisprovidedadequatemarginuntil1990,whenUnit2Cycle8wasstartedup.Atthattime,wehadswitchedtoanewfuelvendorwhoprovideduswithaLLLP.AsresultoftheLLLP,moreofthereactorpowerwasinthecenterofthecore.Asexpected, thiscausedsomefuelassemblies tohavehigherrelativepowers.Thus,creatingsomehottercoreexittemperatures yieldingsubcooling marginsoflessthe29'F,andcausingthesaturation marginmonitors'tanding alarms.Asmentioned intheintroduction, thefoHowingoptionstoeliminate thestandingalarmwereconsidered:

2.3.4.reducethesetpointagain,abandontheLLLPtoachieveamore"flat"powerdistribution, monitoronly"cold"incorethermocouples, andremovethesaturation marginmonitorsalarmingcapability.

Thefirstthreeoptionswererejectedforthefollowing reasons:Reducingthesetpointcouldonlybejustified byourexperience-based knowledge thattheincorethermocouples areaccuratetoapproximately

+5'F(basedonmeasuredpowerdistribution andcalculating theexpectedexittemperatures).

However,thesaturation marginmonitorisforpostaccidentmonitoring andwehavenobasistoremovetheerrortolerances builtintothesetpointforaccidentconditions.

2.3.ThebenefitsoftheLLLPforreducingvesselembrittlement outweighs thebenefitsofhavingthealarmsavailable, forwhichcreditisnottakenandarenotrequired.

Monitoring only"cold"incorethermocouples wouldonlydefeatthepurposeof'hesaturation marginmonitor.Duringanaccident, thefirstcorelocations thatwouldmostlikelylosetheirsaturation margin,orboil,wouldbetheoneswithfuelassemblies withthehighestdecayheat.Theseassemblies wouldtypically bethosewiththehighestcoreexittemperatures.

Therefore, monitoring "cold"assemblies wouldnotbeprudent.Thus,theonlyreasonable solutiontoclearthestandingalarmsistoremovethealarmingcapabilities ofthesaturation marginmonitors.

~\C1 0Attachment No.1toAE.C:1183Page4REVIEWANTAKETIFIATINUREG-0578, NUREG0737andGenericLetter82-18werereviewedtodetermine ifanyrequirements existedcommitting ustoinstallalarmsonoursaturation marginmonitors.

NUREG-0578 andGenericLetter82-18makenostatements regarding saturation marginmonitoralarms.Theonlyreference ofalarmswasfoundinNUREG-0737.

InSectionII.F.2,INSTRUMENTATION FORDETECTION OFINADEQUATE CORECOOLING,Clarification 10,thefollowing isstated:"Thetypesandlocationofdisplaysandalarmsshouldbedetermined byperforming ahuman-factors analysistakingintoconsideration:

(a)theuseofthisinformation byanoperat'or duringbothnormalandabnormalplantconditions, (b)'ntegration intoemergency procedures, (c)integration intooperatortraining, and(d)otheralarmsduringemergency andneedforprioritization ofalarms."Clarification 10revealsthatNUIT-0737 allowedthelicenseetoconsiderwhatwouldprovidethebestinformation ofinadequate corecoolingtotheoperator.

Atthetimeweinstalled thesaturation marginmonitors, thealarmswereaviablemethodforinitially warningtheoperators ofpotential inadequate corecooling.Considering thechangesincoredesignsovertheyears(LLLP),thealarmsassociated withthesaturation marginmonitorsarenolongereffective anddonotassisttheoperatorinassessing inadequate corecooling.Thereasonisthatwehaveastandingalarmduringnormaloperation.

Thusfromahuman-factors standpoint, theoperators arebetterpositioned toidentifyinadequate corecoolingbyrelyingonsaturation marginmonitorreadouts('Fmargin)thanseeinganalarmthatistypically annunciating.

Infact,intheplant'semergency operating procedures, nocreditistakenforthealarmsandtheoperators areinstructed tochecktheamountofsubcooling marginavailable fromtheB&Wsaturation marginmonitororsafetyparameter displaysystem(onthetechnical supportcentercomputerdisplayinthecontrolroom).TheUFSARandTechnical Specifications werereviewedforanyreference tothealarmsonthesaturation marginmonitors.

Thesaturation marginmonitorsarereferenced, butthealarmsarenotmentioned.

NCLUSIONEventhoughthealarmswerediscussed inoursubmittals concerning inadequate corecoolinginstrumentation, therewasnoregulatory requirement toinstallalarmsonsaturation marginmonitors.

Sincethealarmsareonrecordfromourprevioussubmittals, weareproviding thissubmittal showingadequatejustification toremovebothofthesaturation marginmonitors'larming capabilities.

Thiswillbedoneinapproximately 90days.Thealarmsareanuisanceandprovidenousefulinformation tothereactoroperator.

Thehealthandsafetyofthepublicwillnotbeaffectedbyremovingthesaturation marginmonitors'larming capabilities.