ML17037C333

Nine Mile Point Unit 1 - Letter Responding to the March 21, 1972 Letter Requesting Additional Information Regarding Proposed Changes to the Technical Specifications and Bases

ML17037C333
Person / Time
Site:	Nine Mile Point
Issue date:	04/21/1972
From:	Brosnan T J Niagara Mohawk Power Corp
To:	Skovholt D J US Atomic Energy Commission (AEC)
References
Download: ML17037C333 (24)

Text

s'eA."".C..DXSTaRBDTXCi'l:.(.3,PAR'0DOCK""TY~.T"".,XAL(T'""OKERFORa'}IieCONTROLNO;2218PRO~!:NiagaraMohawkPowerCorp.Syracuse,N.Y.13202T.J.BrosnanTO:Mr.Skovholt,DA7."GPDCC:4-21-2ORiG1sied.DAYER!.C'~Hasbls(4-24-2'-XOTfERCCa'asssORP7.Oe~f~%RS"".iTAZCPDRSFNTLOCALPDRxCLASS:U/PROPINFOINPUTNOCYSRZC'D40cysrec'dDOC(ETNO:50-220ECrreourltrdtd.3-21-72,transtheDa-SCRIPTION'ollowing:ENCLOSURES:AddiinforegardingproposedchangestotheTechSpecs8cBasesforNineMilePointStationDONOTREMOjki,IIN~eLEOI(40cysofenclrec'd)."0".ATXONBUTLER(DRL)fJ/CopiesCHIxiJOOD(DiilL)V/CopiesCLARK(DRL)fJ/CopiesH,DENTON/CopiesDICEGR(DRP)fJ/CopiesGOLLER(DRL)!J/CopiesKi"X"L(DRL)P/CopiesKa'iIGHTO'aai(DREP)f('/CopiesSCHi.'(aiZL(D".(L)gZLEfA';J(DRa'4'/Copies8/9CopiesSC1%JZNCER(DRL)fl/CopiesN/CopiesSTOLK(DRL)4'/CopiesW/Copies.VASSAL;.0(DRL)iJ/Cop-csfJ/CopiesINT.::X.':ALDT.S"RiBUTXC!'JM/CopiesfJ/CopiesM/CopiesV/Copiesj5gRcgPilesQAZCPDRQCompliance~(3)PjOGC,RmP506A@'~(!untzing*StaffQMorris/Dube/fiilson(DRL).QMorris/Schroeder(DRL)fsDuhe/43~~(DRL)gfBoyd(DRaL)QDeYoung(DRL)Qif.Dcnton(DRL)Qlilcckcr(DRL)QGrime"(D>,)QGammi11(DRL)QTedesco(DR)QVollmcr(DRL)QSliger(DRL).QLong(DRL)QCollins(DRL)@,Thompson(DRL)D.E.Nunn(DRL)tiBenaroya(DRL)QE.G,Case(DRS)Qa'iaccaxv(DRS)QStcllo(DRS)t3V.Moore(DRS)9Langc(DRS)QSmiley(D~iiL)1lL.Rogers(DREP)Q~iullcr(DREP)~\.sss(~1~~~s~se\s>aass4aas>IQM.I'it"patrick(DREP)~QKastner(DREP)DQLic.Assi:(D";<EP)QMcCreless(DRZP)QG.Blanc(DRZP)QPro-ectLeaae"(DR"P)QDREPPileRoomQA.Draitman(SLR)QSaltzrwan(SLRa)QTrammel(DXP)QTi>ornton(ha~a"af)QKnuth(DRS)QShao(DRS)QPawlckl(DRS)Skovaeolt(DRL19a.aced.KE~Oseec~H.Y.DTXZ(Laughlin)Xi.ASLB{Yorc/h'oodard1IIHIISt)X.6C.~a!iles,C-459,GT1NationalLaboratories1(ANL/OR'(L/Bia"rlL))12"NSXC(i'suchanan)-R.Carroll,OC,GT<<HoldingforQCRS-R.Catlin,A-170,GT-Consultant(Ne',~mark/Blum/Agabian)SA"/aY/aYPDR-ACHQLIBJ00a')-Ch.e4'sterReactors~-'"iiarrenNyer

)l)hka 4Ileggl+OQrfIfpQy~NIAGARAMOHAWKPOWERCORPORATION.,QQF<gAPRR4~972~g%C~ltI5~@6h~NIAGARA~MOHAWKGOOERIKBOULEVARDWEST9YRACU92,H<Y.I3202ApriI2I,l972llyhCe5Mr.DonaIdJ.SkovhoItAssistantDirectorforReactorOperationsDivisionofReactorLicensingUnitedStatesAtomicEnergyCommissionWashington,D.C.20545

DearMr.Skovholt:

IIJ,,Re;:'ocketNo'.'50-220LicenseDPR-l7WesubmittheadditionalinformationrequestedinyourletterofMarch2I,l972regaldingproposed'hangestotheTechnicalSpecificationsandBasesfortheNineMile.PointNuclearStation.Since,testingofthenewreliefvalvesetpoints.requiresdeinertingandaccesstothedrywell,Weplan,subjecttoyourapproval,tomakethesechangesandperformthenecessarytestingduringthecurrentstationoutage.Inadditiontodataonoperationaltransients,yourletteralsorequestedinformationonthepostulatedcontrolroddropaccident.AcompletereanalysisofthisaccidentwillbeforthcomingintheverynearfuturefromtheGeneralElectricCompanyasaTopicalReportgenerictoboilingwaterreactors.0Verytrulyyours,J.BrosnanVicePreient'andChiefEngineer.EnclosuresoI'.,~~-Q0yc~IIyC

't0Cgl$1/I811'YrP QuestionNo.1YoustatethatimprovedanalyticaltechniquesavailableatGeneralElectricCompanycausedyoutoadopttheproposedrevisedscramreactive.tycurve,butnoinformationregardingthesetechniqueswasprovided.Describetheanalyticaltechniquesusedpreviously,thechangesbeingmadetotheanalyticalmodel,andthebasisforconsideringthechangeanimprovement.AnswerNo.1Theimprovedanalyticaltechniqueswhichcausedadoptionofanewscramreactivitycurveinclude:(a)(b)(c)Arevisedpowershapingphilosophyhasbeenfollowedwhichresultsinaflatteraxialpowerdistribution(lowerlinealheatgenerationrates)particularlyatend-of-cycle.ThepowershapinghasbeenaccomplishedbymanagementofcontrolrodpatternsthroughouttheoperatingcycleinaccordancewiththeHalingprinciple.Althoughnotpresently,incorporatedinfuelatNineMilePoint,theuseofaxialshapedgadoliniamayalsobeusedinthefuturetofurtherflattenthepowerdistribution.Anewlatticecodeforcalculationofbundlek'shasreplacedthe2'odeloriginally'usedforNineMilePointfuel.Theuseofthenewlatticecode,asfurtherdescribedherein,alsoresultsinaflatteningoftheaxialpowerdistribution.)IMoredetailhasbeenincorporatedintothemodelforcalculationofscramreactivity.Thechangesdescribedin(b)and(c)havetheeffectofdecreasingthepeakaxialpowerandmovingthepeakawayfromthebottomofthecoreasanequilibriumfuelcycleisapproached.Theseeffects,inturn,reducetheinitialrateofreactivityinsertedbyascrambecauseoftheincreasedtimeintervalbetweenthescraminihtionandthepointwherethecontrolbladesenterthehighpowerregionofthecore.Therevisedpowershapingphilosophyisdirectedtowardmaintainingarelativelyconstantpowerdistributionthroughouteachfuelcycle.Carefu1manage-mentofcontrolrodpatternsduringpoweroperationinaccordancewiththeHalingprinciplewillresultinminimumpeakingattheend-of-cyclewithallcontrolrodsoutofcore.Haling,R.K.,"OperatingStrategyMaintaininganOptimumPowerDistributionThroughoutLife",TID-7672,p.205,(September,l963)AECDocket50-298,BrownsFerryStation,SafetyAnalysisReport,VolumeI,pp.II-6-2AECDocket50-220,NineMilePointNuclearStation,FinalSafetyAnalysisReport,VolumeI,pp.IV-22-24 I%~Ilii 1-2Thenewerlatticecoderesultsinanimprovedcalculationofk~'s.AsignificantdifferenceinthekpredictedbyeachlatticemodelcanbeseenbyexaminationofthecurvesinFigure1-1.Thenewlatticecode'predictshigherk~'sathighvoidandlowerk~'satlowervoidconditionsrelativetotheolderlatticecode.Thisresultsinalowerpredictedpeakpoweratthebottomofthecorewhichreducestheinitialrateofscramreactivity.6Thebasicrefinementsintheanalyticaltechniquesforevaluationofthescramreactivitycurvecharacteristicsreferredto'n(c)aboveincludethefollowingchanges:(a)Anincreaseinthenumberofpromptneutrongroupsfrom1.5to3.(b)Anincreaseinthenumberofaxialnodes.(c)Replacementofthetimeconstantpreviouslyusedtorelateheatfluxtovoidswithatransientthermalhydraulicmodelsimilartothatusedinblowdowntransientanalyses.(d)Addingtheabilitytorepresentcross-sectiondatabasedontypicalexposureandvoidhistory.(e)Animprovedfinitedi.fferencerepresentationojtheone-dimensionaltimedependentfewgroupneutrondiffusionequations.

8 2-1QuestionNo.2DescribethedataandmeasurementsobtainedatNineMilePointfromreactoroperationsandteststhatsupportuseofthenewanalyticaltechniques.AnswerNo.2ThemanagementofcontrolrodpatternsatNineMilePointhasenabledthecoretodevelopandmaintainanaxialpowerdistributionand,therefore,anexposuredistribution,consistentwiththeobjectiveofminimizingpowerpeakingthroughouteachoperatingcycle.Figure2-1comparestheexposuredistributioncalculatedfromNineMilePointreactoroperationasofJanuary,1972,withthe"target"exposuredistributionderivedfromtheHalingprinciple.The"target"exposuredistributionhasbeencomputedforanallrodsoutconditionpriortoremovalofcontrolcurtains,itdoesnotrepresenttheequilibriumend-of-cyclecondition.Confirmationofthenewlatticecodeiseve,dencedbytheabilityofthiscode,inconjunctionwithagobal3-Dsimulator<)topredictpowerdistributionsandrodinventory.Figure2-2comparesthenormalizedpredictedrodinventorytoactualrodinventoryduringtheoperatingperiodjustpriortothecurrentstationshutdown.Xnaddition,comgarisopsofpredictedandobserveddatahavebeenmadeforvariousotherreactors<)(>whicharealsoapplicabletotheNineMilePointreactorindemonstratingthegeneraladequacyofthebasiccomputermodelemployedforthesecalculations.Crowther,R.L.andet.al.,"ThreeDimensionalBNRSimulation"(TED-4500),ProceedingsofConferenceonEffectiveUseofComputersinNuclearindustry,Knoxville,Tennessee,April21-23,1969.,Fuller,E.D.,"PhysicsofOperatingBoilingWaterReactors,"NuclearApplicationsandTechnology,Volume19,pp.622-633,(November,1970).

3-1QuestionNo.3Theeffectofpartialrefuelingsonthescramreactivitycurvehasnotbeenpresented.Pleasedefinetherelationshipofthepresentcoreloadingwiththescramreactivitycurveanddescribetheeffectonthescramreactivityfromapproachinganequilibriumfuelloading,includingtheexpectedoperationalcontrolrodpatterns.AnswerNo.3ThescramreactivitycurveusedintheanalysispresentedinourletterofFebruary28,1972,wasaconservativeestimateofanendconditionforafuelcycleapproximatingtheequilibriumfuelloading.Additionalcalculationshavebeenmadeofaconservativescramreactivitycurvetypicaloftheperiodimmediatelyfollowingremovalofcontrolcurtains'.TheseresultsareshowninFigure3-3.alongwithcurves'usedinpreviousanalyses.Allofthesescramreactivitycurvesareconservativelybasedonascramtimeof5secondsfor90percentinsertion;aconditionwhichdoesnotexistatthisstation.'Figure3-1indicatestherewillbeagradualreductionintheinitialscramreactivityinsertionrateasthecoreapproachesanequilibriumcondition.Figure3-2showsanaxialcontrolrodpositionandtheresultantrelativeaxialpowerdistributionwhichistypicalofexpectedreactorperformancefollowingthecurtainremoval.Otheraxialcontrolrodfractionshavebeenexaminedwhichresultinascramreactivityinsertionrateclosetothatcorrespondingtobeginningoflife.Thesepatternsresultinhighaxialpowerpeakingwhichisnotconsistentwithcurrentdesirestolimittotalpeakingfactors,and,therefore,heatfluxtothoserequiredtoachieveoptimumfuelperformance.

li 4-1QuestionNo.4Youranalysessupportingtheproposedchangesdonotincludeconsiderationofthecontrolroddropaccident.Thechangeinslopeofthescramreactivitycurvewouldindicateanincreasedrateofreactivityinsertionintheeventofacontrolroddropaccident.Provideacompletereanalysisofthisaccident,includingconsiderationofthevalidityoftheassumedmaximumreactivityworthofthecontrolrodinvolvedinthedropaccident.YourattentionisdirectedtoaletterdatedMarch8,1972,toMr.A.P.BrayoftheGeneralElectricCompany'romMr.R.S.Boyd',DivisionofReactorLicensing.Acopyofthisletterisenclosedforyourconvenience.AnswerNo.4ReanalysisofthecontrolroddropaccidentasoutlinedinMr.RogerS.Boyd'sMarch8,1972,lettertoMr.P.A.BrayisnowbeingpreparedbyGeneralElectricandwillbesubmittedtotheCommissionasaTopicalReportintheverynearfutuxe.TheStation'sTechnicalSpecifications(3.1.]b(3))requirethataprescribedcontrolrodwithdrawalsequencebeadheredtoduringplantstartupsinorder'tolimitmaximumrodworth.Specifically,whentherodworthminimizerisnotoperable,asecondlicensedoperatororqualifiedtechnicalstationemployeeshallverifythattheoperatoratthereactorconsoleisfollowingtheprescribedrodwithdrawalsequence.

'l~h1

FIGURE1NINENILEPOINTKC(HOT)VERSUSPERCENTINCHANNELVOIDSINITI'ALfUEL-UNCONTROLLEDCURTAINS-ZEROEXPOSURE~OLDLATTICECODENEWLATTICECODE1020.304050PERCENTINCHANNELVOIDS607080

FIGURE2-1NINEMILEPOINTREACTOR'XIALEXPOSUREDISTRIBUTION1.81.61.4DISTRIBUTION,AT6059MMD/T0.80.6,/ITARGETDISTRIBUTION(PRIOR.TOCURTAINREMOVAL)'.4'.2.00'OTTOM246-.8,10'1214;,AXIALNODES161820,2224261TOP

<<4>4i++A444%A&A%

FIGURE2-2NINENILEPOINTRODINVENTORY.VS.EXPOSURESEQUENCEA-3900OBSERCALCULATEDRODVEDRODINVENTORYINVENTORYC)I-C/)C)O;OMh~UJCACAClEDCLC)CYIC)I-C)I-'00FDI-C)CO500400CD300200,1002,700600'0,500060007000EXPOSURE,MWD/T8000 0'rl t~FIGURE3-lNINEMILEPOINTSCRAMREACTIVITYCURVES-40G(ENDOFCYCLE)EQUILIBRIUMFUELLOADIN-300I-o'20I-,-10BEGINNINGOFLIFE///////////////AFTERCURTAINREMOVAL////r00'3TIME(SECONDS)5 Ay

'.0'IGURENINEMILEPOINT-TYPICALCONTROLFRACTIONANDRELATIVEPOWERVERSUSAXIALPOSITION,(AFTERCURTAINREMOVAL)0.50.4.1.510cn'D0.3CDOClCDCDCYCD.O0.2OCrAXIALCONTROLRODPOSITIONSAXIALPOWER0.50.1AXIALCONTROLRODPOSITROLRODSINSERTEDATAXIALNODETIPN-CONTOTALNUMBEROFCONTROLRODS1290,0.0'2468'10,12141618202224AXIALNODEBOTTOMTOP 0"r>>4('L