ML17249A715

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Forwards Info to Support 791220 Application to Load Four Mixed Oxide Fuel Assemblies in Cycle 10,in Response to NRC 800213 Request.Westinghouse Ltr Re Proprietary Affidavits Encl.Response to Question 6 Withheld (Ref 10CFR.790)
ML17249A715
Person / Time
Site: Ginna Constellation icon.png
Issue date: 02/20/1980
From: WHITE L D
ROCHESTER GAS & ELECTRIC CORP.
To: ZIEMANN D L
Office of Nuclear Reactor Regulation
Shared Package
ML17249A716 List:
References
NUDOCS 8002250526
Download: ML17249A715 (35)


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Forwardsinfotosupport791220applicationtoloadfourmixedoxidefuelassembliesinCycle10ijnresponsetoNRC800213request.westinghouseltrfeproprietaryaffidavitsencl'esponsetoQuestion6withheld(ref10CFR~790)~3PDISTRIBUTIONCODE:PAOISCOPIESRECEIVED:LTR~ENCL/+BAIZE:TITLE:ProprietaryInfoafterIssuanceofLicense~O~~S:LQ'ggA4'tbSSa,4.Mue~4gAMRECIPIENTRECIPIKNTCOPIESIDCODE/NAMEIDCODE/RANELTTRENCLACTION;.02BCOgg4/~COPIESLTTRENCL7"REGULATORYiORMATIONDISTRIBUTIONSYSM(RIDS)ACCESSIONNBR:80'02250526DOC~DATE:80/02/20NOTARIZED:NODOCKETFACIL:50240RobertKmmetGinnaNuclearPlantiUnitiiRochesterG05000240AOTH~NAMEAUTHORAFFILIATIONNHITKeL~D~RocFiesterGas8'ElectricCorp,RECIPBNAMERECIPIENTAFFILIATIONZIEHANNgD~LOperatingReactorsBranch2INTERNAL:0RKGFILE1114ENGRBR116PLANTSYSBR118EFFLTRTSYS1OELD1Ql8'+AS8EXTERNALS19ACRS16NSIC112.1,93009I8E12CORKPERFBR15REACSFTYBR17EEBNRCPDRSTSGROUPLEADR16LPDR4APSMITHEH~H/AFF2~fat@'6/4e-nit00EES)E79~>qSOit'i(2'lTOTALNUMBEROFCOPIESREQUIRED:LTTR~ENCLItI Lf~IIM1(IV4li*fnr DOCiZTNO.SQDATE:p2CP8+NOTETONRCAND/ORLOCALPUBLICDOCUiiENTROOi~iSThefollowingitemsuomittedwithlet"erdatedZ.-Z,OP~fromacer8E/e,e4i'c,disclosureinaccordancewithSection2.790.isbeingwithheldfrompublic?ROPRIETARYINFOR:~iATIONideualDistributionService'sBranch y~

tIIIIIIIIIIIItZtuiitnIII//II///////IIIIROCHESTERGASANDELECTRICCORPORATION101K/I)'IIA11o89EASTAVENUE,ROCHESTER,N.Y.14649I.EOND.WHITE.JR.VICKPRKSIOKNTTKI.KPHONKARKACOOKTIK546-2700February20,1980DirectorofNuclearReactorRegulationAttention:Mr.DennisL.Ziemann,ChiefOperatingReactorsBranchNo.2U.S.NuclearRegulatoryCommissionWashington,DC20555

DearMr.Ziemann:

ByletterdatedFebruary13,1980,yourequestedadditionalinformationtosupportourapplicationofDecember20,1979toloadfourmixedoxidefuelassembliesinGinnaCycle10.AttachmentAtothisletterprovidesourresponses(non-proprietary)toyourquestions.Theresponsetoquestion6,whichaddressesdensi-ficationofGinnamixedoxidefuel,isdeemedtobeproprietarybyitsowner,WestinghouseElectricCorporation.TheproprietaryresponseisprovidedinAttachmentBtothisletter.AsthissubmittalcontainsinformationproprietarytoWestinghouseElectricCorporation,itissupportedbypreviouslysubmittedaffidavitssignedbyWestinghouse,theowneroftheinformation.TheaffidavitssetforththebasisonwhichtheinformationmaybewithheldfrompublicdisclosurebytheCommissionandaddresswithspecificitytheconsiderationslistedinparagraph(b)(4)ofSection2.790oftheCommission'sregulations.Accordingly,itisrespectfullyrequestedthattheinformationwhichisproprietarytoWestinghousebewithheldfrompublicdisclosureinaccordancewith10CFRSection2.790oftheCommission'sregulations.CorrespondencewithrespecttotheproprietaryaspectsoftheapplicationforwithholdingorthesupportingWestinghouseaffidavits,shouldreferenceCAW-80-08,andshouldbeaddressedtoR.A.Wiesemann,Manager,RegulatoryandLegislativeAffairs,WestinghouseElectricCorporation,P.O.Box355,Pittsburgh,Pennsylvania15230.AtotaloffortycopiesofthisletterandofAttachmentAandatotalof3copiesofAttachmentBareprovided.<~+~rpVerytrulyyours,"o~PpL.D.White,Jr.LDW:np8()pap505M AttachmentAResponsestoQuestionsonMixedOxideFuel(Non-Proprietary)hasalowermeltingpointthanUo.WasthisincludedintheoNrpoweraT<ripequation?Ifnor,leaseexplain.R~esonseTheresultsoftheevaluationoftransientswithmixedoxide(MOX)fuelwereshowntobenearlyequivalenttopreviousresults(seeXN-NF-79-103).Asaconsequence,theadequacyoftheoverpowerhTtriplogicwasconfirmedfortheproposedloadingofthemixedoxidefuel.Themixedoxidebundlesarespecificallyplacedinlowpowerregionsofthecore..Thebundleaveragepowerofthemixedoxidebundlesaretobewellbelowthebundleaveragepowerofthecore;hence,it,isanticipatedthatthemixedoxidebundleswillnotapproachconditionsofcenterlinemeltduringreactoroperation.UESTION2ProvideacurveofPuisotopiccontentandUisotopiccontentasafunctionofburnupoftheMOXand'UOfuel.Also,ifavailable,therelativeenergyproducedbyeachisotopeforbothcases.R~esonseAnalyseshavebeenperformedforthemixedoxidefuelassembliesandforthefreshuranium(3.45w/o)fuelassembliesbeingloadedinCycle10.Figures1and2representthePuandUisotopiccontentfortheMOXandUOassemblies,respectively,asafunctionofburnup.Figures3And4representanestimateoftherelativeenergyproducedbyeachisotopefortheabovecases.UESTION3InTable1.1ofXN-NF-77-40,'Rev.1,explainwhytheminimumDNBRdoesnotchangeeventhoughthemaximumpowerlevelandmaximumcoreheat,fluxhavechangedforthesteamlinebreak.~ResonseTheanalysesofinterestinvolvethelargesteamlinebreakincidentwhichhasbeenevaluatedinbothRev.0andRev.1ofXN-NF-77-40.ThereevaluationoftheincidentintheRevision1versionwasmotivatedbyarevisedestimateoftheCycle9pressurereactivityfeedbackandboronworthincomparisontothosevaluesdeterminedforCycle8.

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lW 80I*I-'"IL:....I.70II--60IIIRelativePower.'s..'(IIOXFuel)IExposur'e~~IPu-239-50t~P)~0IcII.CJ...30,II~~~Pu-220-10I..IIi-IIitI*iI~*-I,I~II:ItII-238"IU235~~tI,"..'......':....Ipu.-240.'0481216!.:20:24Exposure'...(6'I(0/HT)i.I,IiIIt:28I!3236'40 JpE 80II70;"IIeIlI~~~III~.IIRelatIFi<iuree'owervs..E1vexposureU02Fuel)2~I;I~%~I~I-60III'I~~PU-239-4030'.I4~~I~~I.I-23-20~,I241u-Ic!U-238!-0041216204..28u-240:,-:--I'-36.40Exposure(GMD/HT)~~~~J 4t TheMDNBRforeachcasediscussedabovewascalculatedconsistentwiththemethodologyusedforothertransientevaluations,andtheresultsaregivenbelow:MDNBRRev.02.21Rev.11.58TheseresultsareconsistentwiththecalculatedincreaseinheatfluxfortheRevision1case,andeachvalueisfarabovetheminimumsafetylimitof1.30fortheW-3correlation.Areevaluationoftheboronreactivityworthduringthesmallsteambreaktransient(asreportedinRev.1toXN-NF-77-40)wasperformedasaresultofareview.ofthereactivitytransientbeyond200seconds.ThisindependentreevaluationindicatesanunderestimationoftheboronreactivityworthinjectedintotheRCSbythereferencedreport.Thepropercalculationofthetotalreactivitypredictioneliminatesthemisleadingindicationthat,returntopowerconditionscouldbeanticipated.Thereevaluationwasanindependentcalcula-tionrelyingonlyontheRCSpressurepredictionfromthereportedanalysis.AcompletereanalysisofthesmallsteamlinebreakincidentwouldbeexpectedtohavecomparableoverallresultswithonlyminorvariationscausedbydifferencesinthemoredetailedtimeintegrationperformedinthePTSanalysis.Ineithercase,returntopowerisnotanticipatedforthesteamlinebreaktransient,andtheoriginaltimescaleofthereportedanalysisissufficienttoestablishreactorsystemprotection.AssumptionsusedintheindependentcalculationaresummarizedinTable1.Table2showsthereportedboronreactivityandtotalreactivityworthscomparedwithvaluesreflectingtheresultofthereevaluation.UESTION4ProvidesomeverificationoftheabilityoftheExxonphysicsmethodstoaccuratelypredict.corebehaviorincorescontainingMOXenrichmentintherangeofthosetobeusedinGinnaforCycle10.R~esonseAdiscussionofENC'sabilitytoaccuratelypredictcorecharacter-isticsofMOXbearingcriticalexperimentsisprovidedinSection4.2("VerificationbyCriticalExperimentComparisons")ofXN-75-27("ExxonNuclearNeutronicDesignMethodsforPressurizedWaterReactors",June1975).InadditionExxonNuclearhasirradiationexperiencewithMOXfuelintwooperatingBWR's.Forty-two(42)assemblieshavebeenirradiatedinBigRockPoint(peakexposureassemblyat30,400MWD/MT)andeighteen(18)intheKahlreactor.

TABLE1BOROHWORTH'REEVALUATIOHASSUHPTIOHSParameterYariable.ValueSourceRCSVolume(ft)BoricAcidTankReserve(gal.)SafetyInjectionLinesVolume(ft)RCSPressure(psia)SafetyInjectionPumpFlow(1pump)No.ofSIPumpsWorkingBoronConcentrationinTanks(ppm);ReactivityWorthofBoron(hp/ppm)TemperatureofBoron('F)PumpStartupDelay(seconds)5973.22000(totalfor2tanks)42(total)27.7(tocoldlegsonly,'1)(2)~'220000.872x10145~10(1)XH-flF-77-40,Rev.1,Figure3.36(2)R.E.GinnaTechnicalSpecifications(ChangeRequest),datedSeptember1976,Figure2.1

TABLE2REACTIVITYTABULTIONS00BORON.REACTIVITYWORTH($)TOTALREACTIVITYWORTH($)~dtd'1td~ddR1td(3)(2)(3',00.0180195210225240255270205300-.04-.70-.74-.76-.78-.80-.82'-.83-.84-.51-1.31-2.07-2.92-3.81-4.71-5.64-6.58-7.52(").79-1.28I-1.14-1.00.86o72.59.47.35-1.26-1.892.473.163.89-4.635.416.227.03(1)Frcmttmeofstart.ofst.earn1tnebreak.(2)Xf(-l>F-77-40,Rev.1.(3)SeeTable.1.(4)Approxtmatelyhalfofthebortcacidremains$nthe1njecttonltnesortanks.

NounusualdifficultieshavebeenencounteredinpredictingthebehaviorofthesecoreswiththepresenceoftheMOXfuel.ItisagainpointedoutthattheGinnaapplicationof4of121assembliesoronlyabout3%ofthecorewillhaveaminimalimpactontheoverallcorecharacteristicsandbehaviorthroughout,thecycle.UESTION5TheproposedchangetotheTechnicalSpecificationsforGinnasaysthattheenrichmentofreloadfuelislimitedto3.5%ofU235oritsequivalentintermsofreactivity.Theequivalenceshouldbespecifiedexactly(abriefdiscussion=intheBasiswouldbeacceptable).Underwhat.conditionsistheequivalencetobeachieved?~ResenseTheTechnicalSpecificationprovidesanupperlimitonreloadfuelenrichment.Wesuggestthatequivalencebedefinedintermsofreactivityinstorageinthespentfuelpool.Thus,aparen-theticalphraseaddedtoTechnicalSpecification5.3.l.cwouldprovidethenecessarydefinition:"(asdefinedbythespentfuelpoolstorageevaluation)".Forthefourmixedoxidefuelassemblies,thespentfuelpoolevaluationprovidedinourDecember20,1979submittaldemonstratesthat.theproposedlimitsaremet.

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0"6.ThestaffSERonMixedOxideFuelstatesthatuseofU02densificationmodelsfortlOXshouldbeverified.{l)SinceitappearsthatthisassumptionwasusedforthettOXfuelforGinna,pleaseverifythisassumption.DoesthepredictedamountofdensificationsatisfyReg.Guide1.126.ThecurrentWestinghouseUO>fueldensificationmodelwasusedtopredict~thedensificationperformanceoftheHOxfuelsfabricatedforGinna.Thisempiricalmodel,whichw'asderivedusingonlyUO>performancedata,usesfuelsinteringtemperatureandsintereddensitytopredicttheextentofdensification.TheapplicationofthemodeltoIt0fuelisjustifiedonXtwobases;thesimilarityinprocedureusedinfabricationofHOfueltoU02proceduresandtheabilitytoconservativelypredicttheperformanceofpreviouslyirradiatedt~iOfuels.XAWhile.studyingthedensificationofpureU02,therelativedimensional.stabilityoffuelwasfoundtobestronglydepergentonthepelletizing.processemployedandthevaluesofkeyprocessingparameters.Theprocessesusedinpelletfabricatio'nforGinnaareessentiallyidenticalwiththoseusedinpreparingHOfuelpreviouslyirradiated'yWestinghousewhoseXperformanceisconservativelypredictedbytheU02model.Further,the.pelletizingprocessesusedforpreparingtheGinnatl0fuelisverysimilarXtothatusedbyWestinghousetoproduceU02fuel.Thelimitingprocessing'parameters,sinteringtemperatureandfinalpelletdensity,werecontrolledtoarangewhichproducesUO>fuelwith.predictedperformancewithindesignrequirements.TheWestinghouseexperiencewithMOdensificationperformanceduringXirradiationhasbeenreportedandcomparedwithmodelpredictionsinWCAP-8349-P.Theoretically,HOdensificationwouldbeexpectedto'proceedatalowerratethaninUO>sinceporeremovalisdirectlyrelatedtolocalfissionevents.DensificationorporeremovalisabulkprocessandinU02fuelthefissioneventsarefairlyuniformlydistributedinthematerialandtheproductdensifiesuniformly..However,inhOXthefissioneventsareconcentratedinorveryneartoPu0>particleswhicharefreetodensifyindependentlyoftheUOpmatrix.ThelowenrichmentUO~matrixexperiencesalowerfr'equency.offissioneventsthannormalenrichedU02fuelatsimilarburnupandshouldshowaloweramountofdensification.Theklestinghouse

11.experiencewithdensificationofHOfueloperatedinacorrmercialpowerXreactoriscomparedwithpredictedvaluesinFigure1whichistakenfromMCAP-8349-P.TheFigvrealsocontainsdatafortheperfonnanceofagg2fuelwithsimilarfabricationcharacteristicsfordirectcomparison.Figure1containsdataforbothmechanicallymixedand"mastermixedfuel.Hastermixedfuelispreparedbyco-precipitatingUO2and:Pu02.,thenmixingtheCo-precipitatedmaterialwithU02.TheU02modelisabestestimatemodelandhencethereshouldbeasmany9,pointswithdensificationunderpredictedasoverpredicted.ThisisobviouslynotthecaseforeithertheU02orHOfuelwiththedensificationXbeinggenerallyoverpredicted.Significantly,thepredictionof'hemodelwasnoticeablymoreconservativefor.theHOfuelthanfortheU02withXsimilarprocessinghistory.AsshowninFigure1,thepredictionformastermixedHOwaslessconservativethanformechanicallymixedHO.ThisisasXX~expectedandfurtherillustratesthelowerdensificationexpectedfromfuels'ithinhomogenouslydistributedfissionevents.TheperformanceofanHO.fuelofhigherPu02contentwhichwasoperatedinX.theSaxtontestreactorwasalsoreportediniiCAP-8349-P.Thisfuel,which.operatedathighertemperaturesthancommercialpowerreactors,wasalsofoundtodensifylessthanpredictedbythemodel.sThepredictivecapabilityoftheU02modelwasfurthertestedbyevaluatingtheperformanceoftheHOfuelintheEPRIHt0densificationprogram.TheseXXfuelswerepreparedbyawidevariationinprocessingvariablesandhencerepresentarangeofconditionsgreaterthanwaspresent.indataonwhichthemodelwasbased.TheperformanceoftheEPRIfuelsasreportedinEPRLHP-637arecomparedwithmodelpredictionsinFigure2.ThedatainFigure2indicatethemodelisessentiallyconservativeorallfuelsshown,eventhoseunstablefuelspreparedbyproceduresdissimilartothoseforfuelonwhoseperformancethemodelisbased.Forthestablefuels,thosewhichdensified<2volumepercent,themodelishighlyconservativeinthatitgreatlyoverpredictsthedensification.TheGinnaHOfuelisXprojectedtobehavestably;allcurrently.manufactured>lestinghouseU02.fuelsarealsoprojectedtoshowstablebehavior.

120Reg.Guide1.126doesnotindicateamaximumamountofdensificationallowablebut,ratherdefinestheamountofdensificationthatmustbeassumedbasedonathermalresinteringtest.Oesignmustaccountfortheamountofdensificationassumedfromtheresintertest.ThermalresinterdataisnotavailablefortheGinnaHOfuelsoanalternateXmethodmustbechosentopredictthedensificationperformance;themethodusedwastheWestinghouseU02model.TheaccuracyofthismodelcanbecomparedtothepredictionsfromthethermalresintermodelinReg.Guide1.126.ThebasisforestablishingtherelativeabilitiesofthetwomodelstopredictperformancewasestablishedbyuseoftheEPRIdata.ThepredictedperformanceusingthethermalresinteringmodeliscomparedwithactualperformanceinFigure3.ExaminationofdatainFigure3indicatesthePresintermodelsignificantlyoverpredictstheamountofdensification,especiallyinthe.regionofstablefuels(<2volumepercentdensification)wheretheoverpredictionisasmuchas2.5percent;ComparisonofFigures2and3indicatestherelativepredictiveabilitiesofthetwo'odels.Thecomparisonshowsthetwomodelsareverys'imilar,bothmodelsbeinggenerally-conservative.Thedegreeofconservatismisfoundtobegreaterintheregionofstablefuels.Similarnumbersofdatapointsare'lightlyunder-predictedbythetwomodels,however,theWestinghousemodel'isbothmoreconsistentandmoreconservativeinthelessthan'2percentdensification'angewhichisrepresentativeoftheGinnaMOfuel.XThedatapresenteddemonstratethattheWestinghouseU02fuel:densificatignmodelyieldspredictionssimilarto'ndmorereliablyconservativeforYOXfuelthantheresintermodelinReg.Guide1.126.

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(.b.c)'COf0O0.5~C7I-.0.00.0~0.5'0'15HEASUREDSTACKLENGTHDECREASE,hL/LORI/3bp/p{PRESENT)FigureComparisonofDensificationDataforUO-3%PvOwithUOBothFabricatedunderSimilarConditionstoaDensityofApproximately91%T.D.

Figure2.WestinghouseUO>ltodelPredictionofDensificationofEPRIHOFuelsX(p,.),c3~f3(DCD0-10ActualChangeinDensity,5 Figure3.Reg.GuidePredictionofEPRIleDataXlP(gOOrQ)r~'zxQR(Q32CJQl<(3QuO(y>g'~0~~g8'~OB'yO(8bslj(7@lgIXl2CblJQHOMechanicallyMixedXeHOxMasterMixedCU02DataNumbersindicateEPRIfueltypes.ActualChangeinDensity 0I'IAf'l 17R~esonseThemixedoxidefuelmechanicaldesignisequivalenttothedesignofGinnafuelregions7,8and9.Theseregionsweredeliveredforinsertionintothereactorin1975,1976and1977,respectively.AllRegion7assemblieshavebeendischargedfromthereactor.Peakassemblyburnupwas31456MWD/MTU.Region8and9fuelassembliesarecurrentlyinthereactor.Region8assemblieswillbedischargedduringthespring1980refuelingoutageandwillnotbereinserted.WeexpectpeakassemblyburnupforRegion8inexcessof34,000MWD/MTU.Region9fuelwillbereinsertedforCycle10withapeakassemblyburnupatthebeginningofCycle10ofnearly25,000MWD/MTU.Performanceoftheseassemblieshas,ingeneral,beenexcellent.Monitoringoftheprimarycoolantactivityhasnotindicatedanyfuelfailuresinthesefuelassemblies.AprogramofvisualexaminationoffuelhasbeenperformedforRegion8fuelnotcurrentlyinthereactor.Thisprogramwasinitiatedbecauseoftheresultsofafuelexaminationatanotherreactorearlierin1979.Thatexaminationindicatedthatrodsfromaparticularingotusedforzircoloytubingdisplayedrodbowing.SincethatingothadalsobeenusedforsomerodsinRegion8fuel,fuelassembliescontainingrodsfabricatedfromthatingotaswellasotherfuelassemblieswerereviewed.It,wasdeterminedthatrodsfromthatingotdiddisplaysomebowbut,thattherewasnobowingdiscernibleinrodsnotfabricatedfromthatingot.Thebowingwaswithinlicensedlimits.Further,nootheranomalieswereseeninthefuel.Peakassemblyburnupforthefuelassemblieswhichwereexaminedwas29067MWD/MTU.Itshouldbenotedthat,noneofthetubingforthemixedoxidefuelwasfabricatedfromthesubjectingot.Fluxtracesfromtheincoredetectorsareobtainedandexaminedatregularintervals."Thesealsoindicateexcellentfuelper-formance.Basedonthecoolantactivityhistory,onthevisualexaminationsandontheincoredetectionmonitoring,weexpectexcellentperformancefromthemixedoxidefuel.UESTION10Table5.2ofXN-NF-79-103showsthatthecontrolrodworthislessforCycle10thanforthepreviouscycle.Isthiseffectduetothepresenceofthemixedoxidefuel?HowwasthiseffectincludedintheaccidentanalysesforCycle10operation.R~esonseTheprimaryeffectresultinginthereductionoftheCycle10controlrodworthsoverthatofpreviouscyclesisduetothecontrolrodsbeingpositionedinassemblieshavingexposuresgreaterthan16,000MWD/MT.Inpreviouscyclessomecontrolrods 1I 'Iwerepositionedin'assemblieswithexposuresofabout5,500to6,700MWD/MT,thusincreasingtheeffectiveworth.ofthecontrolbank.TheeffectoncontrolrodworthduetothepresenceoftheMOXassembliesisassessedtocontributeonlyminoreffects.AsreportedinXN-NF-79-103,thecalculatedcontrolrodworthsstillprovideadeguateshutdownmargin.ThereducedcontrolrodworthsarestillboundedbythepreviouslyusedPTS(XN-NF-77-40,Rev.1)valuesof1,890pcmatBOCand2,830pcmatEOC.Thecorre-spondingvaluesreportedinXN-NF-79-103are4,807pcmforBOCand5,126pcmforEOC.UESTION11ItisknownthattheuncertaintiesassociatedwithpowerdistributioninMOXfuelassembliesareingeneralgreaterthanthoseinUO2fuelassemblies.WasthiseffectconsideredforthefourMOXfuelassembliestobeirradiatedinGinnaforCycle10?~ResonseTheuncertaintiesassociatedwithpowerdistributionsinMOXfuelassemblieswereconsideredwithrespecttoloadingthe4(four)assembliesinthelowpowerregionofthecore(thecoreperiphery).ThisenhancesthemarginswithrespecttotheTechnicalSpecificationlimitsandthepeaklimitingassemblythusallowingforanincreaseduncertainty.DiscussthedifferenceincalculatingtheeffectonF,peakheatfluxfactor,offuelrodbowingsincethecalculationSweredoneforU02fuel.~ResonseTheGinnafuelhasnotdisplayedthetendencytobowashasbeenobservedinotherfuel.ThisisattributedtothespecificfueldesignusedatGinna.Thefuelassemblyutilizesstainlesssteelguidetubesandhas9spacergrids.Thisisasopposedtootherdesignswhichhavezircaloyguidetubesandonly7spacergrids.AsdescribedinourlettersofAugust18,1976andFebruary11,1977andaselaboratedinourresponsetoQuestion9above,inspectionsofGinnafueldemonstratethatthephenomenonnotedatotherfacilitiesarenotobservedatGinna.ThelocalpowerincreasesinMOfuelduetobowedrodsisgreaterthanthatcalculatedforU02full.BasedoncalculationsontheeffectofMO2fuelonpowerspikes,thequalitativeassessmentofWestinghouseisthatalthoughwithagivenamount,ofbowing,MO2fuelwillhavealongerbowingpowerspikethanwillUOfuel,thisisoffsetbythefactthat.GinnafuelhaslessbowingthanassumedintheWestinghouseanalyticalmodel.Therefore,thestatisticalcombinationofpowerpeakingfactoruncertainties("mini-convolution"),asacceptedbytheNRC,resultsinatotalpowerpeakingfactoruncertaintyforGinnaMOfuelconsistentwiththecurrentTechnicalSpecificationlimits.