ML17223B323

TER of Topical Rept CEN-396-P (Verification of Acceptability of a 1-PIN Burnup Limit of 60 Mwd/Kg for St Lucie Unit 2).

ML17223B323
Person / Time
Site:	Saint Lucie
Issue date:	08/31/1991
From:	BEYER C E PACIFIC NORTHWEST RESEARCH CENTER
To:	Office of Nuclear Reactor Regulation
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ML17223B322	List: ML17223B323
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CON-FIN-I-2009 NUDOCS 9111210305
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EnclosureTECHNICALEVALUATIONREPORTTECHNICALEVALUATIONREPORTOFTOPICALREPORTCEN-396-P(VERIFICATIONOFTHEACCEPTABILITYOFA1-PINBURNUPLIMITOF60HWd/kgFORST.LUCIEUNIT2)C.E.BeyerAugust1991PreparedfortheOfficeofNuclearReactorRegulationU.S.NuclearRegulatoryCommissionWashington,D.C.20555underContractDE-AC06-76RLO1830NRCFINI2009PacificNorthwestLaboratoryRichland,Washingtonqiii2i0305950003~9iioiapDpADDER0pDpQp CONTENTS

1.0INTRODUCTION

.........................,,,........,12.0FUELSYSTEMDESIGN....................................3.0FUELSYSTEMDAMAGE.......................................~~~0~~~~2(A)STRESS~~~~~~~~~~~~~~~~~~~~~~~\~~~~~~~~~t~3(8)DESIGNSTRAINe~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~3(C)STRAINFATIGUE...............................................5(D)FRETTINGWEAR.............................................~~~6(E)OXIDATIONANDCRUDBUILDUP..........................~~~~~~~~8(F)RODBOWING...................................................9(G)AXIALGROWTH.................................................10(H)RODINTERNALPRESSURE........................................12(I)ASSEMBLYLIFTOFF.'............................................13(J)CONTROLMATERIALLEACHING....................................144.0FUELRODFAILURE....................................~~~~~~~~~~~~14(A)HYDRIDINGt~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"~~~~~~~~~~~~14(8)-CLADDINGCOLLAPSE............................................15(C)OVERHEATINGOFCLADDING......................................16(D)OVERHEATINGOFFUELPELLETS..................................16(E)EXCESSIVEFUELENTHALPY......................................17(F)PELLET/CLADDINGINTERACTION~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~17(G)CLADDINGRUPTURE...........................~~~~~~~~~~~~~~~~~18(H)MECHANICALFRACTURING.........................,..............19111 5.0FUELCOOLABILITY..................................................19(A)FRAGMENTATIONOFEMBRITTLEDCLADDING..........~~~~~19(8)VIOLENTEXPULSIONOFFUELMATERIAL.....~~~~~~~~~~~~~20(C)CLADDINGBALLOONINGOFFLOWBLOCKAGE.........................20(D)STRUCTURALDAMAGEFROMEXTERNALFORCES.......................2160~00CONCLUSIONS~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~217..0REFERENCES..................................................21 k~NI' TheFloridaPowerandLightCompany(FP8L)hasrequestedtheU.S.NuclearRegulatoryCommission(NRC)toreviewtheCombustionEngineering,Inc.(C-E)topicalreportCEN-396-Pforapproval(Reference1).ThistopicalreportprovidesjustificationforSt.LucieUnit2toachieverod-averagefuelburnuplevelsupto60NMd/kgbforC-E16xl6fuelreloads.Inaddition,C-Eintendstous'ethistopicalreporttojustifytheC-E16xl6fueldesignreloadsinotherC-Eplantstoachieverod-averagefuelburnupsupto60HWd/kgNifthoseapplicationsmeetthefueldesigncriteriadefinedinReference1.TheanalysismethodsanddesigncriteriausedforthissubmittalforSt.LucieUnit2arealsopresentedinReference1.Consequently,thisreviewandresultingTechnicalEvaluationReport{TER)isthesameasthereviewandNRCapprovalforArkansasNuclearOneUnit2(ANO-2)(References2and3)exceptfortheissueofcladdingoxidation[seeSection3.0{E)ofthisreport]whichwasaddressedinareactorspecificmannerforANO-2.Consequently,thisTERreferencesthesamequestionsandANO-2/C-EresponsestothequestionsprovidedintheSafetyEvaluationReport(SER)ofANO-2(Reference3)withtheexceptionofanadditionalquestionaddressedtoFPSLoncladdingoxidation[seeSection3.0(E)ofthisreportforafurtherdiscussionofcladdingoxidationinSt.LucieUnit2].PresentedinthisreportisareviewoftheC-Emechanicaldesigncriteria,andanalysismethodsandresultsfortheSt.LucieUnit2/C-E16xl6fueldesignapplication.Thisreviewwasconductedtoassurethatwhenthedesigncriteria/limitsaremettheywillpreventfueldamageorfailure-andmaintainfuelcoolability,asdefinedintheStandardReviewPlan(SRP)(Reference4),uptorod-averageburnupsof60NWd/kgN.ThisreviewwasbasedonthelicensingrequirementsidentifiedinSection4.2oftheSRP(Reference4).Theobjectivesofthisfuelsystemsafetyreview,asdescribedinSection4.2oftheSRP,aretoprovideassurancethat1)thefuelsystemisnotdamagedasaresultofnormaloperationandanticipatedoperationaloccurrences(AOOs),2)thenumberoffuelrodfailuresisnotunderestimatedforpostulatedaccidents,3)fuelsystemdamageisneversosevereastopreventcontrolrodinsertionwhenitisrequired,and4)cool-abilityisalwaysmaintained.A"notdamaged"fuelsystemisdefinedasonewhereinfuelrodsdonotfail,fuelsystemdimensionsremainwithinoperationtolerances,andfunctionalcapabilitiesarenotreducedbelowthoseassumedinthesafetyanalyses.Objective1,above,isconsistentwithGeneralDesignCriterion(GDC)10(10CFR50,AppendixA)(Reference5),andthedesignlimitsthataccomplishthisarecalledspecifiedacceptablefueldesignlimits(SAFDLs)."Fuelrodfailure"(Objective2)meansthatthefuelrodleaksandthatthefirstfissionproductbarrier(thecladding)has,therefore,beenbreached.Fuelrodfailuresmustbeaccountedforinthedoseanalysisrequiredby10CFR100(Reference6)forpostulatedaccidents.Thegeneralrequirementstomaintaincontrolrodinsertability(Objective3)andcorecoolability(Objective4)appearrepeatedlyintheGOC(e.g.,GOC27and35).Specificcoolabilityrequirementsfortheloss-oF-coolantaccident(LOCA)aregivenin10CFR50,Section50.46(Reference7)."Coolability,"whichissometimestermed"eoolablegeometry,"means,ingeneral,thatthefuelassemblyretainsitsrod-bundlegeometricalconfigurationwithadequate coolantchannelstopermitremovalofresidualheatevenafterasevereaccident.InordertoassurethattheabovestatedobjectivesaremetandfollowtheformatofSection4.2oftheSRP,thisreviewcoversthefollowingthreemajorcategories:1)FuelSystemDamageMechanisms,whicharemostapplicabletonormaloperationandAOOs;2)FuelRodFailureMechanisms,whichapplytonormaloperation,AOOs,andpostulatedaccidents;and3)FuelCoolability,whichisappliedtopostulatedaccidents.SpecificfueldamageorfailuremechanismsareidentifiedundereachofthesecategoriesinSection4.2oftheSRPandtheseindividualmechanismsareaddressedinthisreport.TheC-Edesigncriteria,andanalysismethodsandresultsforthe16x16fueldesignuptoarod-averageburnupof60MWd/kgM,willbediscussedinthisreportundereachfueldamageorfailuremechanism.PacificNorthwestLaboratory(PNL)hasactedasaconsultanttotheNRCinthisreviewofReference1andthepreviousreviewforANO-2(Reference2).AsaresultofthereviewofReference2bytheNRCstaffandtheirPNLcon-sultants,alistofquestionsweresentby.theNRCtoANO-2(Reference8)requestingfurtherjustificationonwhylowmeasuredcladdingductilities,greatercladdingoxidation,guidewear,claddingcollapse,andaxialassemblygrowtharenotlimitingattheburnuplevelrequested.ANO-2providedresponsestothesequestionsinReferences9and10.TheresponsessubmittedbyANO-2inReference3werejointlydevelopedbyANO-2andC-Estaffand,therefore,willbereferredtoasANO-2/C-Eresponses.TheANO-2/C-Ere-sponsesinReferences9and10areapplicabletoSt.LucieUnit2,withtheexceptionofcladdingoxidation,becausethiswasidentifiedasareactor-specificissueinNRC'sapproval(Reference3)ofReference2.ThedesigncriteriaandanalysessubmittedbyFP&LinsupportofthelicensesubmittalforSt.LucieUnit2arethosedefinedinReference1byC-Eand,therefore,willbereferredtoasC-Edesigncriteriaandanalyses.Asnotedearlier,anadditionalquestionwassentbyNRCtoFP&L(Reference11)concerningcladdingoxidationinSt.LucieUnit2uptotheburnuplevelrequested.FP&L/St.LucieUnit2hasprovidedawrittenresponseinReference12andadditionalverbalresponseswerereceivedfromFP&LandC-EinaJune21,1991conferencecall.TheC-E16x16designdescriptionisbrieflydiscussedinthefollowingsection(Section2.0).ThefueldamageandfailuremechanismsandC-EanalysesofthesemechanismsareaddressedinSections3.0and4.0,respectively,whilefuelcoolabilityisaddressedinSection5.0.2.0FUELSYSTEMDESIGNTheC-E16x16fueldesigndiscussedinthesubjecttopicalreporthasnotchangedfromthatdescribedpreviouslyinReference13,therefore,thereaderisdirectedtothisearlierreportforadesigndescription.3.0FUFLSYSTEMDAMAGEThedesigncriteriapresentedinthissectionshouldnotbeexceededduringnormaloperation,includingAOOs.Undereachdamagemechanism,thereisan evaluationofthedesigncriteriaanalysismethodsandanalysesusedbyC-Etodemonstratethatfueldamagedoesnotoccurforthe16x16designduringnormaloperation,includingAOOs,uptoarod-averageburnupof60NWd/kgM.(A)STRESSBases/Criteria-InkeepingwiththeGDC10SAFDLs,fueldamagecriteriaforstressshouldensurethatfuelsystemdimensionsremainwithinoperationaltolerancesfornormaloperationandAOOs,andthatfunctionalcapabilitiesarenotreducedbelowthoseassumedinthesafetyanalysis.TheC-Edesignbasis~forfuelassembly,fuelrod,burnablepoisonrod,andupper-endfittingspringstressesisthatthefuelsystemwillbefunctionalandwillnotbedamagedduetoexcessivestresses(References14and15).TheC-EstresscriteriaforthefuelassemblycomponentsareprovidedinReferences13and16.Thedesignlimitforfuelrodandburnablepoisonrodcladdingisthatthemaximumprimarytensilestressislessthantwo-thirdsoftheZircaloyyieldstrengthasaffectedbytemperature.ThedesignlimitoftheInconelX-750upper-endfittingspringisthatthecalculatedshearstresswillbelessthanorequaltotheminimumyieldstressinshear.Manyofthesebasesandlimitsareusedbytheindustryatlarge.C-Ehasemployedvariousconservatismsinthelimitssuchastheuseofunirradiatedyieldstrengthsforzirconium-basedalloys.TheNRChaspreviouslyconcluded(Reference15)thatthefuelassembly,fuelrod,burnablepoisonrod,andupper-endfittingspringstressdesignbasesandlimitswereacceptableforrod-averageburnuplevelsupto52NWd/kgN.Extendingtheburnuplevelto60MWd/kgNdoesnotreducetheapplicabilityofthesecriteriaand,thus,PNLconcludesthatthesecriteriaareacceptableforuseinthecurrentappli-cationtotheC-E16x16designuptoarod-averageburnupof60MWd/kgH.Evaluation-C-Ehasstatedthatthemethodsusedtoperformstressanalyseswillnotchangefromthoseusedandapprovedforpreviousapplications.TheseanalysesareperformedusingconventionalengineeringformulasfromstandardengineeringmechanicstextbooksandperformedinaccordancewithASMEgeneralguidelinesforanalyzingprimaryandsecondarystresses.TheNRChascon-cluded(Reference15)thatthesestressanalysesareacceptableforrod-averageburnuplevelsupto52MWd/kgM.Extendingtherod-averageburnuplevelto60NWd/kgNdoesnotreducetheapplicabilityofthesemethodsand,thus,PNLconcludesthattheseanalysismethodsareacceptableforapplicationtotheC-E16x16designuptoarod-averageburnupof60NWd/kgH.AsnotedinSection3.0(E),stressanalysesatextendedburnuplevelsarerequiredtoincludetheeffectsofcladdingthinningduetocladdingoxidation.(B)DESIGNSTRAINBases/Criteria-Withregardtofuelassemblydesignstrain,theC-EdesignbasisfornormaloperationandAOOsisthatpermanentfuelassemblyde-flectionsshallnotresultincontrolelementassembly(CEA)insertiontime beyondthatallowable.Thisbasisissatisfiedbyadherencetothestresscriteriamentionedaboveandstraincriterionyettobediscussed.Thesubmittedtopicalreportprovidesadesigncriterionforfuelrodandburnablepoisonrodcladdinguniformcircumferentialstrain(elasticplusplastic)ofonepercent(1%)as"ameansofprecludingexcessivecladdingdeformation.ThisstraincriterionisconsistentwiththatgiveninSection4.2oftheSRP.Thematerialpropertythatcouldhaveasignificantimpactonthecladdingstraincriterionattherequestedextendedburnuplevelsiscladdingduc-tility.Thestraincriterioncouldbeimpactedifcladdingductilityweredecreased,asaresultofextendedburnupoperations,toalevelthatwouldallowcladdingfailurewithoutthe1%claddingstraincriterionbeingexceededintheC-Eanalyses.RecentmeasuredcladdingandplasticcladdingstrainvaluesfromC-Efuelrods(Reference17)andotherpressurized-waterreactor(PWR)fuelvendors(Reference18)haveshownadecreaseincladdingduc-tilitieswhenlocalburnupsexceed52HWd/kgH.Thecladdingplasticstrainvaluesdecreasedto0.03to0.11%whenlocalburnupswerebetween55and63HWd/kgH.-ANO-2/C-Ewasquestionedonwhetherthesesignificantreductionsincladdingplasticductilitiesjustifiedadecreaseinthe1.0%designcriterionfortotaluniformstrain(elasticplusplastic)forC-Efuelwithlocalburnupsgreaterthan55HWd/kgH(Reference8).ANO-2/C-Eresponded(Reference9)thatbecauseoftheincreaseintheyieldstrengthandthecorrespondingincreaseinelasticstrainofthecladdingduetoirradiation,thetypicalelasticstrainswereabove1%usingnominalvaluesforirradiatedyieldstrengthandYoung'smodulusatburnupsgreaterthan55HWd/kgH.ANO-2/C-Ewasfurtherquestionedinaconferencecallabouttheprobabilitythatthecombinedelasticplusplasticstrainsbetween55and63HWd/kgHwouldfallbelowthe1%straincriterion.ANO-2/C-Epresented(Reference10)astatisticalanalysisoftheirmeasuredyieldstrengthdatafromcladdingwithlocalburnupsgreaterthan55HWd/kgHandcalculatedatolerancelimitaboutthemeanvalueforyieldstrength.TheyalsocalculatedatolerancelimitaboutthemeanvalueforYoung'smodulususingdatafromtheopenliterature.UsingthelowerboundtolerancelimitforyieldstrengthandtheupperboundtolerancelimitforYoung'smodulusplustherangeofplasticstrain,theycalculatedthatthereisa9%probabilitythatcladdingstrainwouldfallbelowthe1%totallimitforastrainlimitatburnupsgreaterthan55HWd/kgH.PNLhasperformedanindependentsimplifiedstatisticalanalysisusingaone-sidedlowertolerancelimitata7%probabilitylevelofthemeasuredyieldstrengthsatburnupsgreaterthan55HWd/kgHandaone-sideduppertolerancelimitata7%probabilitylevelofthemeasuredvaluesforYoung'smodulus.DividingthelowertolerancelimitforyieldstrengthbytheuppertolerancelimitforYoung'smodulusitiscalculatedthatthereisslightlygreaterthana7%probabilitythatcladdingstrainwillfallbelowthe1.0%totaluniformstrainlimitatlocalburnupsbetween55and63HWd/kgH.The7%probabilityoffallingbelowthe1.0%strainlimitcalculatedisconservativebecausethissimplifiedapproachhasassumedthatcombiningtheyieldstrengthandYoung'smodulustolerancelimitswillresultinanequivalentplasticstraintolerance

limit.HallandSampson(Reference19)haveprovidedamoreexactanalyticalprocedurefordeterminingeitherone-sidedortwo-sidedtolerancelimitsforthedistributionofthequotient(e.g.,plasticstrain)oftwoindependentnormalvariables(e.g.,yieldstrengthandYoung'smodulus)forthisappli-cation.Thismoreexactanalyticalprocedureresultsinlessthana7%probabilityoffallingbelowthe1.0%strainlimitatlocalburnupsbetween55and63HWd/kgM.Therefore,because1)thereisalowprobabilityoftotaluniformstrainfallingbelow1%intheC-E16x16fuelcladding,2)conservativepowerhistoriesareusedintheC-Estrainanalysis,and3)nofuelfailureshavebeenobservedonfuelrods-irradiatedwithrod-averageburnupsto63MWd/kgH,PNLconcludesthatthe1%totaluniformstrainlimitremainsapplicablefortheC-E16x16fueldesigninSt.LucieUnit2uptoarod-averageburnupof60MWd/kgM.However,PNLrecommendsthatfuturerequeststoextendtherod-averageburnuplimitbeyond60MWd/kgMshouldbeaccompaniedwithmeasuredcladdingstrain,andyieldandfracturestrengthdataattheextendedburnuplevelsrequested.Thisdataisnecessarytodemonstratethatthetotaluniformstraincriterionof1%remainsapplicableatthesehigherburnupsandthatfuelcladdingbrittlefracturewillnotoccurduringnormaloperationandAOOsatthesehigherburnups.Evaluation-C-EutilizestheFATES38(Reference20)computercodetopredictcladdingstrainandotherfuelperformancephenomenaathighburnuplevels.ThiscodehasbeenapprovedbytheNRCforfuelperformanceanalysesuptorod-averageburnupsof60HWd/kgM(Reference21).TheFATES38codewilltaketheplaceoftheearlierFATES3code(Reference22).Therefore,PNLconcludesthattheuseoftheFATES38codeforcalculatingcladdingstrainfortheC-E16x16fueldesigninSt.LucieUnit2isacceptableforrod-averageburnupsupto60HWd/kgM.(C)STRAINFATIGUEBases/Criteria-TheC-EstrainfatiguecriterionisdifferentfromthosedescribedinSection4.2oftheSRP,i.e.,asafetyfactorof2onstressamplitudeorof20onthenumberofcyclesusingthemethodsofO'DonnellandLanger(Reference23).Instead,C-Ehasproposed,inthepast,thatthecumulativestraincyclingusage(i.e.,thesumoftheratiosofthenumberofcyclesinagiveneffectivestrainrangetothepermittednumberinthatrange)willnotexceed0.8.ForZircaloycladding,thedesignlimitcurvehasbeenadjustedtoprovideastrainmarginfortheeffectsofuncertaintyandirradiation.TheresultingcurvegiveninReferences13and14boundsallofthedatausedinthedevelopmentofthecriterionthatisdiscussedintheSRP.TheNRChaspreviouslyconcludedthattheproposedcriterionwasacceptableforcurrentburnuplevels(Reference15).Thematerialpropertythatcouldhaveasignificanteffectonthestrainfatiguecriterioniscladdingductility.Asdiscussedintheabovesectionfordesignstrain,extendedburnupoperationabovelocalburnupsof55HWd/kgMresultsinasignificantreductionincladdingductilities.However,asalsodiscussedherein,thereisalowprobabilitythatcladdingductilitywillfallbelowtheacceptablelimitfortotaluniformstrainatarod-averageburnupof lgEf 60NWd/kgM.Inaddition,thereisaconsiderableamountofconservatismintheC-Estrainfatigueanalysismethodology.Therefore,PNLconcludesthatthestrainfatiguecriterionproposedinReference1isacceptableforlicensingapplicationstoC-,E16xl6fuelinSt.LucieUnit2uptoarod-averageburnupof60HWd/kgM.Evaluation-ThefuelandcladdingmodelsusedtodeterminefuelandcladdingdiametralstrainforthefatigueanalysisarethoseintheFATES38code(Reference20)whichhasbeenapprovedbytheNRC(Reference21).ThepowerhistoryusedforthefatigueanalysisincludesconservativeestimatesofdailypowercyclingandAOOsandhasbeendescribedpreviouslyinReference14.Thisanalysisalsoaccountsforaconservativenumberofhotandcoldshut-downsduringthefuellifetime.Thispowerhistorytakesintoaccounttheextradutyrequiredforrod-averageburnupsupto60MWd/kgM.Therefore,PNLconcludesthattheC-Estrainfatigueanalysismodelsreferencedareaccepta-bleforapplicationtotheC-E.16x16fueldesigninSt.LucieUnit2uptoarod-averageburnupof60HWd/kgM.,(0)FRETTINGWEARBases/Criteria-Frettingwearisaconcernforfuelandburnablepoisonrods,andtheguidetubes.Frettingwearmayoccuronthefueland/orburnablerodcladdingsurfacesincontactwiththespacergridsifthereisareductioningridspacerspringloadsincombinationwithsmallamplitude,flow-induced,vibratoryforces.Guidetubewearmayresultwhenthereisflow-inducedvibrationbetweenthecontrolrodendsandtheinnerwalloftheguidetubes.WhileSection4.2oftheSRPdoesnotprovidenumericalboundingvalueacceptancecriteriaforfrettingwear,itdoesstipulatethattheallowablefrettingwearshouldbestatedinthesafetyanalysisreportandthatthestress/strainandfatiguelimitsshouldpresumetheexistenceofthiswear.ThesubmittedtopicalreporthasaddressedfuelandburnablepoisonrodfrettingwearbyreferringtoReference14andstatingthatnosignificantwearhasbeenobservedforC-Efuelrodsandnoadditionalfrettingwearwasexpectedduetotheextensionofrod-averageburnuplevelto60HWd/kgH.IndicatedinReference14isthataspecificfrettingwearlimitwasnotusedforC-Efuelassemblycomponents,becauseithasnotbeen'aproblemforcurrentC-Efueldesigns.ThissameargumentwasusedtoexplainwhyfrettingwearwasnotaccountedforinthefuelandburnablepoisonrodanalysesForcladdingstressandfatigue.Inordertosupportthisclaim,inthepreviousreview(Reference15),C-Eprovidedfuelexaminationinformationfrom744assemblieswithaverageburnupsuptoapproximately52MWd/kgMthatshowednofailuresorsignificantwearonthesurfaceoftheirfuelorburnablepoisonrods.Itisnotedthatsincethistime,C-Ehasperformedavisualexaminationof14xl4designedfuelrodsirradiatedtorod-averageburnupsupto56MWd/kgMandfoundnosurfaceanomaliesotherthanminorscratches(Reference17).Becauseofthelackofsignificantfrettingwearintheexaminationofmorethan744C-Efuelassemblies,withrod-averageburnupsto56MWd/kgMandexistingfuelsurveillanceprograms,PNLconcludesthatC-Ehasdemonstrated

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thatfrettingwearintheirfuelandburnablepoisonrodswillbeacceptableuptorod-averageburnupsof60HWd/kgH.Guidetubewear,however,wasobservedinseveralC-Efuelassembliesin1977.Sincethenadesignchangeintheguidetubeshasgreatlyreducedguidetubewearforboth14xl4and16x16fuelassemblydesigns.However,itwasnotedintheNRCreviewofReference14thatverylimitedlowburnupdatawereavail-ableforthisnewguidetubedesign(Reference15).ANO-2/C-Ewasrequested(Reference8)toprovideguidetubeweardataforthenewunsleevedguidetubedesigntobeusedinthesubjectreloadandfutureC-E16xl6plantreloadsandcomparethisdatatotheirmaximumpredictedwearcorrelation.ANO-2/C-Eprovided(Reference9)thiscomparison,whichdemonstratedthatthemeasuredweardataisafactorof3belowtheC-Ecorrelationformaximumwearforboth14x14and16x16fuelassemblydesigns.However,itshouldbenotedthatthemaximumin-reactoroperatingtimesoftheweardataareonlyone-thirdofthoseexpectedforrod-averageburnupsto60HWd/kgH.TheANO-2/C-Eresponse(Reference9)arguedthatthislackofweardataatthemaximumburnuplevelrequestedwassatisfactorybecause1)theC-Emaximumguidetubefrettingwearcorrelationisveryconservative,and2)thereisalargemarginbetweenmaximumpredictedfrettingwearatthemaximumburnuplevelrequestedandtheminimumamountofallowablewearthataguidetubecansustainwithoutviolatinganydesigncriteria.DuetotheconservativenatureoftheC-Eguidetubefrettingwearcorrelationandthelargemarginthatexistsbeforedesigncriteriaareviolated,PNLconcludesthatguidetubewearintheC-E16xl6fueldesignisacceptableuptoarod-averageburnuplevelof60HWd/kgH.Evaluation-TheSt.LucieUnit2/C-EsubmittalhassuggestedthatthelackofalargeamountofmeasuredfrettingwearinC-Efuelandburnablepoisonrodssupportstheirconclusionthattheydonotneedtoincludetheeffectsofcladdingthinningduetofrettingwearintheirstress,strain,andfatigueanalysesforthefuelandburnablepoisonrods.However,thisdoesnotanswerthequestionofwhatthecalculatedimpactofasmallreductionincladdingthicknesshasonsafetyanddesignanalyses,e.g.,LOCAandstress/strain.Inthepast,C-E(Reference14)hasindicatedthatthemostlimitingLOCAanalysisisearly-in-lifewhenstoredenergyisthehighestandfrettingwearisinsignificantforthisanalysis.PNLagreeswiththisassessment.ANO-2/C-Ealsorespondedtoaquestiononcladdingthinningduetooxidationbystatingthattheyconservativelyreducethecladdingthicknessofthe16xl6fuelrodsby3milsintheirstressanalysis[seeSection3.0(E)].ThisinclusionofcladdingthinningduetocorrosionisjudgedtoboundthinningduetofrettingwearbecausecorrosionisthegreaterofthetwothinningmechanismsforC-E'scurrentfueldesignsandbecausethesetwomechanismsdonotoccursimultaneouslyatthesamelocationonafuelrod.Forexample,wherefrettingwearispresentonthefuelorburnablepoisonrod,oxidationwillnotbepresentandviceversa.Therefore,PNLconcludesthatcladdingthinningofthefuelandburnablepoisonrodsduetofrettingwearareboundedbyC-E'sanalysisofcladdingthinningduetooxidation.Asnotedinthe"Criteria"section,guidetubewearhasbeenaprobleminthepastforC-Eassemblies.Designhangestoreduceguidetubewearhavebeen P't$q~'~

implementedbyC-Eforboth14x14and16x16assemblies.Bothout-of-reactorandin-reactorconfirmationtestshavebeenperformedtoshowthatthesedesignchangeshaveresultedinasignificantdecreaseinguidetubewearforin-reactorresidencetimesthatareone-thirdofthoseexpectedforanextendedburnuplevelof60HWd/kgH.Extrapolatingtheguidetubeweartothein-reactorresidencetimeexpectedforanextendedrod-averageburnuplevelof60HWd/kgHhasdemonstratedthatguidetubewearwillremainatarelativelylowlevel.PNLconcludesthatguidetubewearisnotexpectedtobeaproblemuptoarod-averageburnupof60HWd/kgHforthenewlydesignedguidetubesintheC-E16x16designinSt.LucieUnit2(basedonthelowlevelofwearat.lowerburnups).PNLrecommendsthatthelicenseecontinuetoexamineguidetubesuptotheextendedburnuplevelsrequestedtoconfirmthatwearisnotaproblemattheseburnuplevels.(E)OXIDATIONANDCRUDBUILDUPBases/Criteria-Section4.2oftheSRPidentifiescladdingoxidationandcrudbuildupaspotentialfuelsystemdamagemechanisms.Generalmechanicalpropertiesofthecladdingarenotsignificantlyimpactedbythinoxidesorcrudbuildup.Themajormeansofcontrollingfueldamageduetocladdingoxidationandcrudisthroughwaterchemistrycontrols,materialsusedintheprimarysystem,andfuelsurveillanceprogramsthatareallreactorspecific.Becausethesecontrolsarealreadyincludedinthespecificreactordesign,adesignlimitoncladdingoxidationandcrudisconsideredtoberedundantand,thus,.notnecessary.Thisdoesnot,however,eliminatetheneedtoincludetheeffectsofcladdingoxidationandcrudinthermalandmechanicallicensinganalysesasperSection4.2oftheSRP.Thisissueisofparticularconcernforextendedburnupoperationinthosereactorsthathaveshownhighlevelsofcladdingcorrosionatlowerburnuplevels.Thiswillbediscussedinfurtherdetailintheevaluationpresentedbelow.Evaluation-Theamountofcladdingoxidationexpectedforaparticularreactorisdependentonfuelrodpowers(surfaceheatflux),chemistrycontrolsandprimaryinletcoolanttemperaturesusedbythatreactor,buttheamountofoxidationincreaseswithin-reactorresidencetimeandcannotbeeliminated.Therefore,extendingtherod-averageburnuplevelto60HWd/kgHcouldresultin1)thickeroxidelayersthatprovideanextrathermalbarrierthatincreasescladdingandfueltemperatures,and2)claddingthinningthatcanaffectthemechanicalanalyses.Thedegreeofthiseffectonthermalandmechanicalanalysesisdependentonreactorcoolanttemperaturesandthelevelofsuccessofareactors'hemistrycontrols.TheSt.LucieUnit2/C-Esubmittal(Reference1)hasprovidedoxidethicknessmeasurementsfromfuelrodcladdingirradiatedinANO-2neartheburnuplevelrequestedandplacedaconservativeupperbound3n(standarddeviation)limitonthemeasuredvalues.TheNRCquestionedFP&L(Reference11)ontheappli-cabilityoftheANO-2claddingoxidationdatatoSt.LucieUnit2withrespecttothosereactorspecificparametersthatimpactcladdingcorrosion.FP&Lhasresponded(Reference12)thatcladdingtemperaturesinSt.LucieUnit2arelowerthanforANO-2di,etolowercoolanttemperatureandcoreaveragerod powersbutthatlithiumlevelsinthecoolantofSt.LucieUnit2aregreater.Thesetwoparametershaveopposingeffectsoncladdingcorrosion;i.e.,lowercladdingtemperaturesdecreasecorrosionbuthigherlithiumlevelshavebeenshowntoincreasecorrosionbyasmallamount.Consequently,FP8Lhasconcluded(Reference12)thatwhileitislikelythatcorrosioninSt.LucieUnit2willbesimilartothatinANO-2itisimpossibletostatethattheANO-2claddingoxidationdatabasewillboundSt.LucieUnit2claddingoxidation.FPIILandC-EwerefurtherquestionedinaconferencecallwithNRCandPNLon0une21,1991onthemaximumlevelofoxidationusedforthethermalandmechanicalanalysesforC-E16x16fuelinSt.LucieUnit2andwhetherFPSLintendstomonitoroxidethicknesslevelsinSt.LucieUnit2inordertoconfirmthatthemaximumthicknesslevelassumedbyC-Eisbounding.C-ErespondedthattheyusedthemaximumupperboundoxidethicknessmentionedinSection4.1.2.2.aofReference1forthethermalanalysesuptoarod-averageburnupof60HWd/kgH.Fortheirstressanalyses,C-Estatedthattheyreducedtheas-fabricatedcladdingthicknessbyaproprietarypercentagetoaccountforcladdingimperfectionswearandoxidation.C-EhasfurtherstatedthattheresultsofboththeirthermalandmechanicalanalysesoftheC-E16x16fuelinSt.LucieUnit2arewithinthestatedcriteriaforsatisfactoryper-formance.PNLhasreviewedtheequivalentoxidethicknesslevelsusedbyC-Efortheirstressandthermalanalyses,andconcludesthatbasedonavailabledatathesethicknesslevelswillboundthemaximumoxidethicknessforC-E16x16fuelinSt.LucieUnit2uptoarod-averageburnupof60HWd/kgH.FPELhasalsoindicatedthattheyintendtomonitorcladdingoxidethicknessuptoarod-averageburnupof60HWd/kgHinordertoconfirmthattheoxidethick-nessandcladdingthinningvaluesusedbyC-EintheiranalysesareboundingforSt.LucieUnit2.Therefore,PNLconcludesthatcladdingoxidationisacceptablefortheC-E16x16fueldesigninSt.LucieUnit2uptoarod-averageburnupof60HWd/kgH.Thereisanindicationthatcladdingcorrosionmaylimitthefuelrodper-formance.lifetimeforhigherburnupirradiationsforspecificplants.Becausecladdingoxidationisdependentonreactor-specificconditionssuchasreactorcoolanttemperaturesandwaterchemistryitisnecessarytoexaminecladdingoxidationonareactor-specificbasisuntilC-Ehasabroadenoughcladdingcorrosiondatabasetoboundthosereactorspecificparametersthataffectcorrosionatextendedburnups.Therefore,PNLrecommendsthatfuturerequeststoextendtherod-averageburnuplimitbeyond60HWd/kgHshouldbeaccompaniedwithreactor-specificcorrosiondataattheburnuplevelsrequested.(F)RODBOWINGBases/Criteria-Fuelandburnablepoisonrodbowingarephenomenathatalterthedesign-pitchdimensionsbetweenadjacentrods.Bowingaffectslocalnuclearpowerpeakingandthelocalheattransfertothecoolant.Ratherthanplacingdesignlimitsontheamountofbowingthatispermitted,theeffectsofbowingareincludedinthesafetyanalysis.ThisisconsistentwiththeSRPandtheNRChasapprovedthisforcurrentburnuplevels(Reference15).Themethodsusedforpredictingthedegreeofrodbowingattheextendedburnupsrequestedareevaluatedbelow.

Evaluation-TheC-Eanalysismethodsusedtoaccountfortheeffectoffuelandpoisonrodbowingin14x14and16xl6fuelassembliesarepresentedinReference14andCENPD-225(Reference24)withitssupplements.ThesemethodshavebeenapprovedbytheNRC(References15and24)forfuelandType3poisonrodstocurrentburnuplevels.C-Ehascompared14x14rodbowdatawithburnupsto45NWd/kgMtotheirlicensingrodbowmodel(Reference14)anddemonstratedthatthemodelbecomesmoreconservativeathigherburnups.Thesedataappeartosuggestthattherateofrodbowsignificantlydecreasesatburnupsgreaterthan30to35NWd/kgH,whiletheC-Eanalyticalmodelforrodbowassumeslittleornodecreaseintherateofrodbowingwithburnup.Thisresultsinvery'conservativepredictionsofrodbowinginC-E14x14designedfuelathighburnuplevels.TheC-Erodbowingmodelfor16x16fuelrodswasalsodemon-stratedinReference14tobeveryconservativebycomparisontodatawithburnupsupto33NWd/kgN.ANO-2hasindicatedthattheyroutinelyperformvisualexaminationoftheirfuelassembliestoprovideassurancesofsatis-factoryperformanceoftheirfuel.ThephenomenonofrodbowingisgenerictoallLWRseventhoughdesigndifferencessuchasthelengthbetweenspacersandroddiameterareimportanttotheamountofrodbowing.Therefore,otherfuelvendorexperiencewithrodbowingisvaluableinevaluatingthetrendinrodbowingatextendedburnups.FRANATONEhasmeasuredrodbowontheirFRAGEHAfuelassembliesforfuelburnupsupto53NWd/kgNandfoundthattherateofrodbowingversusburnupdecreasesatburnupsgreaterthan30to35NWd/kgH(Reference25).SimilarmeasurementsofrodbowinghavebeenmadebyKraftwerkUnionAG(KWU)ontheirfueldesignsuptoburnupsof50NWd/kgN(Reference26)andfoundthatduetothescatterintheirlimiteddata,thedecreaseintherateofrodbowingwasnotasevidentasthatdemonstratedinReferences14and25.However,KWUdidfindthatrodbowingwaslimitedtogapclosuresoflessthan4NontheirfueldesignswhichisconsistentwiththedatainReference14.PNLconcludesthattheC-Eanalysismethods(Reference24)appliedtotheC-E16xl6fueldesigninSt.LucieUnit2willremainconservativeuptotheextendedburnuplevelrequestedand,therefore,areacceptableuptoarod-averageburnuplevelof60HWd/kgN.(G)AXIALGROWTHBases/Criteria-Thecorecomponentsrequiringaxial-dimensionalevaluationaretheCEAs,burnablepoisonrods,fuelrods,andfuelassemblies.TheCEAsarenotincludedinthisextendedburnupreview.Thegrowthofburnablepoisonandfuelrodsismainlygovernedbya)theirradiationandstress-inducedgrowthoftheZircaloy-4cladding,andb)thebehaviorofpoison,'uel,andspacerpellets,andtheirinteractionwiththeZircaloy-4cladding.Thegrowthofthefuelassembliesisafunctionofboththecompressivecreepandtheirradiation-inducedgrowthoftheZircaloy-4guidetubes.FortheZircaloycladdingandfuelassemblyguidetubes,thecriticaltolerancesthatrequirecontrollingarea)thespacingbetweenthefuelrodsandtheupperfuelassemblyfitting(i.e.,shouldergap),andb)thespacingbetweenthefuelassembliesandthecoreinternals.Failuretoadequatelydesignforthe10 formermayresultinfuelrodbowing,andforthelattermayresultincollapseandfailureoftheassemblyhold-downsprings.Withregardtoinadequatelydesignedshouldergaps,problemshavebeenreported(References27,28,29,and30)inforeign(ObrigheimandBeznau)anddomestic(GinnaandANO-2)plantsthathavenecessitatedpredischargemodificationstofuelassemblies.Forburnablepoisonandfuelrods,C-Ehasadesignbasisthatsufficientshouldergapclearancesmustbemaintainedthroughoutthedesignlifetimeofthefuelata95%confidencelevel.Similarly,forfuelassemblyaxialgrowth,C-Ehasadesignbasisthatsufficientclearancemustbemaintainedbetweenthefuelassemblyandtheupperguidestructurethroughoutthedesignlifetimeofthefuelassemblyata95%confidencelevel.Thisbasisallocatesafuelassemblygapspacing,whichwillaccommodatethemaximumaxialgrowth,whenestablishingthedesignminimuminitialfuelassemblyclearancewithrespecttothecoreinternals.Thesedesignbasesandlimitsdealingwithaxialgrowthpreventmechanicalinterferenceand,thus,havebeenapprovedbyNRCforpreviousextendedburnuplevels(Reference15).PNLconcludesthatthesedesignbasesandlimitswillensurethatcontactispreventedand,thus,arefoundtobeacceptableFortheC-E16x16fueldesignto60MWd/kgM.Evaluation-TheC-Emethodsandmodelsusedforpredictingfuelrodandassemblygrowthinthissubmittal(ReferenceI)havebeenchangedsomewhatfromthosepreviouslyapprovedinReference14tobetterpredictthenewhigherexposuregrowthdata.Thisevaluationwilldiscussthenewrevisedmodelsusedtopredictfuelrodandassemblygrowth.AlsopresentedishowC-EusestheserevisedmodelstopredictI)theshouldergapspacingsbetweenthefuelrodandtheupperfuelassemblyfitting,and2)thegapspacingbetweenthefuelassemblyandcoreinternals.ThenewrevisedfuelandburnablepoisonrodgrowthmodelisbasedonC-E14xl4.and16xl6roddatawithrod-averageburnupsabovethoserequested.Themodelpredictsa"bestestimate"valueofrodgr'owthwithuncertainties.ThenewrevisedassemblygrowthmodelisbasedontheSIGREEPcomputercodeandgrowthdatafromassemblieswithstressreliefannealed(SRA)guidetubeswithassemblyaverageburnupsbelowthoserequestedinthissubmittal.TheSIGREEPpredictionofassemblygrowthtakesintoaccountthedifferentaxialstressesontheguidetubesfordifferentC-EplantfuelassembliesincludingtheSt.LucieUnit2assembliesandusesinputparameterswithassignedsta-tisticaluncertaintiesalongwithMonteCarlorandomselectiontechniquesandcombinationsoftheseuncertaintiestoobtainaprobabilitydensityfunctionofassemblygrowthatagivenfluence(burnup)level.TheC-EevaluationofshouldergapspacingusesthelowerboundprobabilitydensityfunctionforassemblygrowthandtheupperboundprobabilitydensityfunctionforrodgrowthwithuncertaintiesintheSIGREEPcomputercodetopredicttheshouldergapatanupperbound95%probabilitywitha95%confi-dencelevel.ThisC-Emethodologyforpredictinganupperbound95/95shouldergapspacinghasbeencomparedtomeasuredshouldergapdata(ReferenceI)thathaveassembly-averageburnupsbelowthoserequestedinthissubmittal.TheseC-Eupperboundpredictionsdoindeedboundtheshouldergapdataandappeartobecomeevenmoreconservativeatthehigherburnuplevels.11 Itshouldbenotedthatintheshouldergapcalculationtheamountoffuelrodgrowthismuchgreaterthantheamountofassemblygrowth,therefore,thepredictionoffuelrodgrowthdominatestheanalysisofshouldergapspacing.ItshouldalsobenotedthattheC-Erodgrowthdatahaverod-averageburnupsgreaterthanthoserequestedinthissubmittal.PNLconcludesthattheC-EanalysismethodologyisacceptableforapplicationtotheC-E16x16designuptoarod-averageburnupof60MWd/kgMbecause1)C-Ehasfuelrodgrowthdataabovetheburnuplevelrequested,2)fuelrodgrowthdominatestheshouldergapspacinganalysis,and3)thelargeamountofconservativemarginC-Ehasdemonstratedintheirpredictionofshouldergapspacing.TheC-EanalysisofthegapspacingbetweentheupperfuelassemblyandcoreinternalsusestheSIGREEPprobabilitydensityfunctionforassemblygrowthtopredictaminimum95/95valueforthisgapspacinginordertopreventbottomingoutoftheassemblyhold-downsprings.BecauseC-Edoesnothaveassemblygrowthdatauptotheburnuplevelrequested,theywerequestioned(Reference8)onthegapmarginthatexistsattheburnuplevelrequestedinthissubmittaltopreventbottomingofthe'hold-downspring.ANO-2/C-E'sresponse(Reference9)indicatedthattherewasapproximatelyone-thirdoftheoriginalas-fabricatedgapspacingleftpriortobottomingoutofthehold-downspringattheburnuprequested.ThissamesignificantmarginingapspacingshouldexistfortheC-E16x16fuelinSt.LucieUnit2.DuetothissignificantmarginandC-E'sconservativeanalysismethodology,PNLconcludesthatbottomingoutandfailureofthehold-downspringduetofuelassemblygrowthisnotexpectedfortheC-E16x16designuptoarod-averageburnupof60MWd/kgM.However,PNLrecommendsthatSt.LucieUnit2visuallyexaminethehold-downspringstoconfirmthatthereissignificantmarginofthecompressibilityofthesespringsinthoseassembliesdischargedwithrod-averageburnupsnearoratthe60MWd/kgMlevel.(H)RODINTERNALPRESSUREBases/Criteria-Rodinternalpressureisadrivingforcefor,ratherthanadirectmechanismof,fuelsystemdamagethatcouldcontributetothelossofdimensionalstabilityandcladdingintegrity.Section4.2oftheSRPpresentsarodpressurelimitthatissufficienttoprecludefueldamageinthisregard,andithasbeenwidelyusedbytheindustry;itstatesthatrodinternalgaspressureshouldremainbelowthenominalsystempressureduringnormaloperation,unlessotherwisejustified.C-EhaselectedtojustifyarodinternalpressurelimitabovesystempressureinReference31andthisproprietaryrodpressurelimithasbeenapprovedbyNRC.TheC-Edesigncriterionusedtoestablishthisproprietaryrodpressurelimitis:"Thefuelrodinternalhotgaspressureshallnotexceedthecriticalmaximumpressuredeterminedtocauseanoutwardcladdingcreepratethatisinexcessofthefuelradialgrowthrateanywherelocallyalongtheentireactivelengthofthefuelrod."Inaddition,C-Ehasevaluatedtheimpactofthisrodpressurelimitonhydridereorientationandaccidentanalyses.Therefore,PNLconcludesthattheNRCapprovedrodpressurelimitdefinedinReference3112 isalsoacceptableforapplicationtotheC-E16x16fueldesigntoarod-averageburnupof60HWd/kgM.Evaluation-C-EhasindicatedthattheywillusetheFATES3B(Reference20)computercodetocalculatemaximumrodinternalpressuresandthiscodehasbeenapprovedbyNRCinReference21.TheFATES3Bcodehasbeenverified,againstfissiongasreleasedatafromavarietyoffueldesignswithrod-averageburnupsupto60HWd/kgH.TheuseoftheapprovedFATES3BcodeisrecommendedovertheearlierapprovedFATES3code(Reference22)becausetheformerhasbeenverifiedagainstamuchlargerdatabaseathigherburnup~levels.ANO-2/C-EwerequestionedontheapparentsmallunderpredictionoffissiongasreleasebytheFATES3Bcodewhenfissiongasreleasevalueswerelow(<3/release)athighburnuplevelsandtheimpactofthisunderpredictiononlicensinganalyses.ANO-2/C-Erespondedthatlicensinganalysesaretypicallyperformedinaconservativemanneronthepeakoperatingrod,i.e.,arodwithhightemperatures,highfissiongasrelease,andhighinternalrodpressuresand,therefore,thesmallunderpredictioninfissiongasreleaseatlowtemperatureswereinsignificantforlicensinganalyses.Theyalsodemon-stratedthattheamountofunderpredictionwassmallintermsofcalculatedinternalrodpressuresintheselowtemperaturerods.PNLconcurswiththisassessmentandconcludesthattheFATES3BcodeisacceptablefortheanalysisofinternalrodpressuresfortheC-E16xl6fueldesignuptoarod-averageburnupof60HWd/kgM.Inadditiontothecomputercode,theinputpowerhistorytothecodeisveryimportantfortheinternalrodpressurecalculation.Consequently,C-EhasbeenrequiredbyNRC,inthepast,todefineamethodologyfordeterminingthepowerhistoryfortherodpressurecalculation.ThismethodologywasfirstreviewedandapprovedforReference14andC-EhasprovidedanexampleofhowthismethodologyisappliedinReference1.Therefore,PNLconcludesthattheuseoftheapprovedFATES3BcodealongwiththeapprovedC-EpowerhistorymethodologydescribedinReferencesIand14isacceptableforlicensingapplicationsfortheC-E16x16fueldesignuptoarod-averageburnupof60HWd/kgM.(I)ASSEHBLYLIFTOFFBases/Criteria-TheSRPcallsforthefuelassemblyhold-downcapability(wetweightandspringforces)toexceedworst-casehydraulicloadsfornormaloperation,whichincludesAOOs.TheNRC-approvedC-EExtendedBurnupTopicalReport(Reference14)hasendorsedthisdesignbasis.PNLconcludesthatthisdesignbasisisalsoacceptableforapplicationtotheC-E16x16fueldesignuptoarod-averageburnupof60HWd/kgM.Evaluation-C-EmethodologyforassemblyliftoffanalysishasbeensummarizedinReference2andapprovedbytheNRCforcurrentburnupsinReference15.Thefuelassemblyliftoffforceisafunctionofplantcoolantflow,springforces,andassemblydimensionalchanges.Extendedburnupirradiationwillresultinadditionalhold-downspringrelaxationandassemblylengthincreaseswhichwillhaveopposingeffectsontheassemblyhold-downforce,i.e.,the13 F'Et~

lengthincreasewillcompressthespringand,therefore,increasethehold-downforce.Industryexperiencehasdemonstratedthattheassemblylengthincreaseduetoirradiationmorethancompensatesforspringrelaxationsothatthehold-downforceincreaseswithincreasedburnup.Infact,amajorconcernatextendedburnupsisthattheassemblylengthchangewillcompressthespringtotheextentthatitwillbottomoutandbreak.ThisissuehasbeenaddressedsatisfactorilyinSection3.0(G),"AxialGrowth."Conse-quently,PNLconcludesthattheissueofassemblyliftoffhasbeensatis-factorilyaddressedfortheC-E16x16fueldesigntoarod-averageburnupof60HWd/kgH.(J)CONTROLMATERIALLEACHINGBases/Criteria-TheSRPandGDCrequirethatreactivitycontrolbemain-tained.Rodreactivitycansometimesbelostbyleachingofcertainpoisonmaterialsifthecladdingofcontrol-bearingmaterialhasbeenbreached.Evaluation-Reactivitylossfromburnablepoisonrodsatextendedburnuplevelsisfoundtobeinsignificantbecausenearlyallofthereactivitycontrollingboron-10isburnedoutattheseburnuplevels.Consequently,reactivitylossduetoleachingofburnablepoisonrodsattheextendedburnuplevelrequested.isconsideredtobeinsignificant.ControlrodlifetimesarenotchangedinthissubmittalfromthosepreviouslyapprovedbytheNRCand,therefore,arenotaffectedbythisrequesttoextendfuelrodaverageburnupsto60HWd/kgH.PNLconcludesthattheissueofcontrolmaterialleachinghasbeensatisfactorilyaddressedfortheC-E16x16fueldesignuptoarod-averageburnupof60HWd/kgH.4.0FUELRODFAILUREInthefollowingparagraphs,fuelrodfailurethresholdsandanalysismethodsforthefailuremechanismslistedintheSRParereviewed.WhenthefailurethresholdsareappliedtonormaloperationincludingAOOs,theyareusedaslimits(andhenceSAFOLs)sincefuelfailureunderthoseconditionsshouldnotoccuraccordingtothetraditionalconservativeinterpretationofGOC10.Whenthesethresholdsareusedforpostulatedaccidents,fuelfailuresarepermitted,buttheymustbeaccountedforinthedosecalculationsrequiredby10CFR100.ThebasisorreasonforestablishingthesefailurethresholdsisthusestablishedbyGDC10andPart100andonlythethresholdvaluesandtheanalysismethodsusedtoassurethattheyaremetarereviewedbelow.(A)HYDRIDINGBases/Criteria-Internalhydridingasacladdingfailuremechanismisprecludedbycontrollingthelevelofhydrogenimpuritiesduringfabrication.ThemoisturelevelintheuraniumdioxidefuelislimitedbyC-Etoaproprietaryvaluelessthan20ppm,andthisspecificationiscompatiblewiththeASTHspecification(Reference32)whichallowstwomicrogramsofhydrogenpergramofuranium(i.e.,2ppm).ThisisthesameasthelimitdescribedintheSRPandhasbeenfoundacceptablebyNRC(Reference15)andPNLconcludes14 thatitcontinuestobeacceptableforapplicationtotheC-E16xl6fueldesignuptoarod-averageburnupof60HWd/kgH.Externalhydridingduetowatersidecorrosionisapossiblereasonfortheobservedductilitydecreaseatlocalburnups>55HWd/kgHdiscussedinSection3.0(B).Garde(Reference33)hasrecentlyproposedthattheduc-tilitydecreaseisduetoacombinationofhydrideformationandirradiationdamageatthesehighburnuplevels.TheissueofcladdingductilityhasalreadybeendiscussedinSection3.0(B)ofthisTERandfoundtobeaccepta-blefortheC-E16xl6designuptoarod-averageburnupof60MWd/kgH.Evaluation-Theissueofinternalhydridingisnotexpectedtobeaffectedbyanincreaseinrod-averageburnuplevelbecausethisfailuremechanismisdependentontheamountofhydrogenimpuritiesintroducedduringfuelfabri-cation.Fuelfailuresduetointernalhydridingoccurearlyinafuelrods'ifetimeandarenotdependentonthelengthofirradiation.BecauseC-Elimitsthelevelofhydrogenimpuritiesintheirfuelfabricationprocess,PNLconcludesthatthismethodologyisacceptableforapplicationtotheC-E16xl6fueldesignuptoarod-averageburnupof60HWd/kgH.Themajorissueforexternalhydridingatextendedburnuplevelsisanincreaseinhydridingthatresultsinadecreaseincladdingductilityreducingthethresholdforcladdingfailure.TheissueofdecreasedcladdingductilityattheextendedburnuplevelrequestedhasalreadybeendiscussedinSection3.0(B)ofthisreportandPNLconcludesitisacceptablefortheC-E16x16fueldesignuptoarod-averageburnupof60HWd/kgH.(B)CLADDINGCOLLAPSEBases/Criteria-Ifaxialgapsinthefuelpelletcolumnweretooccurduetodensification,thecladdingwouldhavethepotentialofcollapsingintothisaxial.gap(i.e.,flattening).Becauseofthelargelocalstrainsthatwouldresultfromcollapse,thecladdingisassumedtofail.ItisaC-Edesignbasisthatcladdingcollapseisprecludedduringthefuelrodandburnablepoisonroddesignlifetime.ThisdesignbasisisthesameasthatintheSRPandhasbeenapprovedbytheNRC(Reference15).PNLconcludesthatthisdesignbasisisalsoacceptablefortheC-E16x16fueldesignuptoarod-averageburnup=of60HWd/kgH.Evaluation-Thelongerin-reactorresidencetimesassociatedwiththeburnupextensionrequestedforFPLL,fuelwillincreasetheamountofcreepofanunsupportedfuelcladding.Extensivepostirradiationevaluations(Reference14)byC-Ehavenotshownanyevidenceofcladdingcollapseorlargelocalovalitiesintheirfueldesigns.Thisisprimarilytheresultoftheiruseofprepressurizedrodsandstable(non-densifying)fuelincurrentgenerationdesigns.Inaddition,C-EhasperformedseveralpostirradiationexaminationsthathavelookedforaxialgapformationintheirmodernfueldesignsandconcludedthatthelargestmeasuredgapsaremuchsmallerthanthoserequiredtoachievecladdingcollapseforcurrentC-Efueldesignsatarod-averageburnupof60HWd/kgH(ReferenceI).TheseC-Emeasuredcoldaxialgapshavebeen15 SS correctedtohotaxialgapsinthefuelrodduringin-reactoroperationforthecladdingcollapseanalysis.ANO-2/C-Ehasstatedthatthe.resultinghotgapusedinthecladdingcollapseanalysisisinexcessofthatexpectedata95%probabilityanda95KconfidencelevelbasedonaC-Estatisticalanalysisofthehotgaps(Reference9).Thiscladdingcollapseanalysishasdemon-stratedthattheC-E16x16claddingwillnotcollapseatarod-averageburnupgreaterthan60HWd/kgH.Therefore,ANO-2/C-EhasproposedthattheynolongerberequiredtoaddresscladdingcollapsefornewcoresorreloadbatchesoftheC-E16x16designunlessdesignormanufacturingchangesareintroducedwhichwouldsignificantlyreducecladdingcollapsetimesforthisfueldesign.PNLconcludesthatthisproposedapproachisacceptableforfutureC-Ecoresorreloadbatchesofthe16x16designandrecommendsthattheissueofcladdingcollapsebereevaluatedshouldrod-averageburnupsexceed60HWd/kgH.(C)OVERHEATINGOFCLADDINGBases/Criteria-Thedesignlimitforthepreventionoffuelfailuresduetooverheatingisthattherewillbeatleasta955probabilityata95%confi-dencelevelthatthedeparturefromnucleateboilingratio(DNBR)willnotoccuronafuelrodhavingtheminimumDNBRduringnormaloperationandAOOs.ThisdesignlimitisconsistentwiththethermalmargincriterioninSection4.2oftheSRPand,thus,hasbeenfoundacceptableforapplicationtoC-Efueldesigns(Reference14).Thisdesignlimitisnotimpactedbytheproposedextensioninburnup.Therefore,PNLconcludesthatthisdesignlimitremainsacceptableforapplicationtotheC-E16x16fueldesignuptoarod-averageburnupof60HWd/kgH.Evaluation-AsstatedinSection4.2oftheSRP,adequatecoolingisassumedtoexistwhenthethermalmargincriteriontolimittheDNBRorboilingtran-sitioninthecoreissatisfied.TheanalysismethodsemployedtomeettheDNBRdesignbasisareprovidedinReferences34through39.TheseanalysismethodshavebeenapprovedbyNRCforcurrentburnuplevelsandPNLconcludesthattheyarealsoacceptableforapplicationtotheC-E16x16designuptoarod-averageburnupof60HWd/kgH.TheimpactofrodbowingonDNBfortheC-E16x16designinANO-2hasbeenaddressedinReference35.PNLconcludesthatANO-2/C-EhasadequatelyaddressedtheissueofcladdingoverheatingfortheC-E16x16designuptoarod-averageburnupof60MWd/kgM.(D)OVERHEATINGOFFUELPELLETSBases/Criteria-Asasecondmethodofavoidingcladdingfailureduetooverheating,C-EprecludescenterlinefuelpelletmeltingduringnormaloperationandAOOs.ThisdesignlimitisthesameasgivenintheSRPandhasbeenapprovedforuseatcurrentlevels.PNLconcludesthatthisdesignlimitisalsoacceptablefortheC-.E16x16fueldesignuptoarod-averageburnupof60HWd/kgH.Evaluation-ThedesignevaluationofthefuelcenterlinemeltlimitisperformedwiththeapprovedC-Efuelperformancecode,FATES3B(Reference20).16 Thiscodeisalsousedtocalculateinitialconditionsfortransientsandaccidents.Asnotedearlier,theFATES3Bcodehasbeenacceptedforfuelper-formancecalculationsuptoarod-averageburnupof60HWd/kgH(Reference21).IntheC-Ecenterlinemeltinganalysis,themeltingtemperatureoftheU02isassumedtobe5080'Funirradiatedandisdecreasedby58'Fper10MWd/kgH.ThisrelationhasbeenalmostuniversallyadoptedbytheindustryandhasbeenpreviouslyacceptedbytheNRC(Reference15).RecentUO~fuelmeltingdatabyKomatsuwithburnupsto30MWd/kgMhaveshownnodiscePnibledecreaseinmeltingtemperaturewithburnup,andadropo'fapproximate'ly20'fper10HWd/kgHforU02-20%Pugwithburnupsupto110HWd/kgH(Reference40).ThisdemonstratestheconsrvatismemployedbyC-2intheirfuelmelting,temperatureanalysisatextendedburnuplevels.Therefore,PHLconcludesthattheC-EanalysismethodsforfuelmeltingareacceptableforapplicationtotheC-E16x16fueldesignuptoarod-averageburnupof60MWd/kgH.(E)EXCESSIVEFUELENTHALPYBases/Criteria-TheSRPguidelinesforaseverereactivityinitiatedaccident(RIA)inaPWR,Section4.2.II.A.2(f),statethatfor"allRIAsinaPWR,thethermalmargincriteria(ONBR)areusedinafuelfailurecriteriatomeettheguidelinesofRegulatoryGuide1.77(Reference41)asitrelatestofuelfailure."C-EhasadoptedthiscriterionforfuelfailureinadditiontoothermorestringentcriteriaforRIAs(Reference42).Evaluation-TheNRCapprovedanalysismethodsforevaluatingRIAsinC-EplantsisprovidedinReference42.PNLconcludesthattheapprovedanalysismethodsdescribedinReference42arestillapplicabletotheburnupextensionrequestedand,therefore,areacceptableforapplicationtotheC-E16x16fueldesignuptoarod-averageburnupof60MWd/kgH.Thesteady-statefueloperationaldatathatareinputtotheCEAejectionanalysisfromtheFATES3Bcodearedependentonfuelburnups.Asnotedearlier,PNLconcludesthattheFATES3Bcodeisacceptableforsteady-statefuelperformanceapplicationsforC-E16xl6fueluptothe60MWd/kgHrod-averageburnuplevelrequestedinth1ssubmittal.(F)PELLET/CLADDINGINTERACTIONBases/Criteria-AsindicatedinSection4.2oftheSRP,therearenogenerallyapplicablecriteriaforPCIfailure.However,twoacceptancecriteriaoflimitedapplicationarepresentedintheSRPforPCI:1)lessthanIXtransient-inducedcladdingstrain,and2)nocenterlinefuelmelting.BothoftheselimitsareusedinC-Efueldesigns[seeSections3.0(B)and4.0(D)]andPNLconcludesthattheyareacceptableinthisapplication.Evaluation-Asnotedearlier,,C-EusestheFATES3Bcode(Reference20)todemonstratethattheirfuelmeetsboththecladdingstrainandfuelmeltcriteria.Thiscodehasbeenfoundtobeacceptablefortheseapplications[seeSections3.0(B)and4.0(0)]and,therefore,PNLconcludesthatitsuseisacceptableforevaluatingPCIfailuresforC-E16x16fueldesignsuptoarod-averageburnupof60MWd/kgH.17 C-EhasalsopresentedPCIpowerrampingtestsonfuelrodsthataresimilartotheirfueldesignsuptorod-averageburnupsofapproximately48HWd/kgHthatdemonstratethattherampterminalpowerlevelforfuelfailuredoes'notdecreasewithincreasedburnup.Inaddition,themaximumpowercapabilityofextendedburnupfuelisreducedbecauseoffissilematerialburnout;there-fore,limitingthedrivingforceforPCIfailures.Consequently,PNLcon-cludesthatC-E16x16fueldesignshaveadequatePCIresistanceuptoarod-averageburnupof60HWd/kgH.(G)CLADDINGRUPTUREBases/Criteria-Zircaloycladdingwillburst(rupture)undercertaincombi-nationsoftemperature,heatingrate,anddifferentialpressure;conditionsthatoccurduringaLOCA.WhiletherearenospecificdesigncriteriaintheSRPassociatedwithcladdingrupture,therequirementsofAppendixKto10CFRPart50mustbemetasthoserequirementsrelatetotheincidenceofruptureduringaLOCA;therefore,arupturetemperaturecorrelationmustbeusedintheLOCAemergencycorecoolingsystem(ECCS)analysis.TheseAppendixKrequirementsforcladdingrupturearenotimpactedbytheSt.LucieUnit2requesttoextendrod-averageburnupto60HWd/kgHand,therefore,PNLconcludesthattheserequirementsremainapplicabletoC-E16xl6fueldesignsuptotheburnuplevelrequested.Evaluation-AnempiricalcladdingcreepmodelisusedbyC-EtopredicttheoccurrenceofcladdingruptureintheirLOCA-ECCSanalysis.TherupturemodelisdirectlycoupledtothecladdingballooningandflowblockagemodelsusedintheNRCapprovedECCSevaluationmodeldescribedinReference43.TheC-EcladdingrupturemodelisnotaffectedbyFPEL'srequesttoextendtheirburnuplimit.Therefore,PNLconcludesthattheC-EmodelforcladdingruptureforLOCA-ECCSanalysesisacceptableforapplicationtotheC-E16xl6fueldesignuptoarod-averageburnupof60HWd/kgH.Anotherconcernraisedduringprevioushigh-burnupreviews(Reference31)isthatthesehigherburnupscanresultinfuelrodpressuresthatexceedsystempressureandthesehigherfuelrodpressurescanaffectcladdingruptureduringaLOCA.ForthoseC-Efuelreloadsthathavecalculatedpeakrodpressuresabovesystempressure,C-Ehaspreviouslyagreed(Reference31)toreevaluatetheirLOCA-ECCSanalysestodeterminethemostlimitingLOCAcon-ditionsforthesereloads.Therefore,PNLconcludesthatC-EhasaddressedtheissueoffuelrodpressuresexceedingsystempressureoncladdingruptureintheLOCA-ECCSanal'ysis.Thoseimportantparametersthatareinputtotheruptureanalysisthatcanbeburnupdependent,suchasrodpressures,fissiongasrelease,fuelstoredenergy,andgapconductancearecalculatedwiththeNRCapprovedcodeFATES38.Asnotedearlier,theFATES38codehasbeenverifiedwithdatauptorod-averageburnupsof62HWd/kgHand'approvedto60MWd/kgH.Therefore,PNLconcludesthattheuseoftheFATES38codeisacceptableforinputtoLOCA-ECCSanalysesoftheC-E16xl6fueldesignuptoarod-averageburnupof60HWd/kgH,asrequestedinthissubmittal.18 0kl (8)MECHANICALFRACTURINGBases/Criteria-Mechanicalfracturingofafuelrodcouldpotentiallyarisefromanexternallyappliedforcesuchasahydraulicloadoraloadderivedfromcore-platemotion.Toprecludesuchfailure,theapplicanthasstated(Reference14)thatfuelrodfracturestresslimitsshallbeinaccordancewiththecriteriagiveninTable9-1ofCENPD-178,Revision1(Reference44).ThereviewofCENPD-178,Revision1andthecriteriagiveninTable9-1(Reference44)hasbeencompletedandfoundacceptablebyNRCforcurrentburnuplevels(Reference15).TheC-EfracturestresslimitsinReference45areconservativelybasedonunirradiatedZircaloypropertiesandarejudgedtoremainconservativeuptoarod-averageburnupof60HWd/kgHforthemechani-calfracturinganalysis.Consequently,PNLconcludesthatthesecriteriaarealsofoundtobeacceptableforapplicationtotheC-E16xl6designuptoarod-averageburnupof60MWd/kgM.However,PNLrecommendsthatfuturerequeststoextendtheburnupbeyond60HWd/kgMshouldbeaccompaniedwithmeasuredcladdingyieldandfracturestrengthdatatodemonstratethattherodfracturestresslimitsdescribedinReference44remainconservativeuptotheburnuplevelrequested.Evaluation-Themechanicalfracturinganalysisisdoneasapartoftheseismic-LOCAloadinganalysis.Adiscussionoftheseismic-LOCAloadinganalysisisgiveninSection5.0(D)ofthisreport.5.0FUELCOOLABILITYForaccidentsinwhichseverefueldamagemightoccur,corecoolabilitymustbemaintainedasrequiredbyseveralGDCs(e.g.,GDC27and35).Inthefollowingparagraphs,limitsandmethodstoassurethatcoolabilityismaintainedfortheseveredamagemechanismslistedintheSRParereviewed.(A)FRAGMENTATIONOFEMBRITTLEDCLADDINGBases/Criteria-ThemostsevereoccurrenceofcladdingoxidationandpossiblefragmentationduringanaccidentisaresultofasignificantdegreeofcladdingoxidationduringaLOCA.InordertoreducetheeffectsofcladdingoxidationforaLOCAC-Eusesanacceptancecriteriaof2200'Fonpeakcladdingtemperatureanda17%limitonmaximumcladdingoxidationaspre-scribedby10CFR50.46.PNLconcludesthatthesecriteriaprovidedbyC-EfortheLOCAanalysisareacceptableforapplicationtotheC-E16x16fueldesignuptoarod-averageburnupof60HWd/kgH.Evaluation-TheNRC-approvedcladdingoxidationmodelsinReference45areusedbyC-Etodeterminethattheabovecriteriaaremet,asaresultoftheLOCAanalysis.Thesemodelsarenotaffectedbytheproposedextendedburnupoperation;however,thesteady-stateoperationalinputprovidedtotheLOCAanalysisisburnupdependent.Asnotedearlier,thoseburnupdependentparametersimportanttotheLOCAanalysis,suchasstoredenergy,gapcon-ductance,fissiongasrelease,androdpressuresfromsteady-stateoperation,areprovidedbytheFATES3Bcode(Reference20).Also,asnotedearlier,FATES3BisacceptableforprovidinginputtotheevaluationofLOCAuptothe19

~L%il~p requestedrod-averageburnupof60HWd/kgH.PNLconcludesthattheuseofReference45isalsoacceptableforevaluatingcladdingoxidationandfragmen-tationduringaLOCAfortheC-E16x16fueluptotherod-averageburnuplevelrequestedinthissubmittal.(B)VIOLENTEXPULSIONOFFUELHATERIALBases/Criteria-InaCEAejectionaccident,largeandrapiddepositionofenergyinthefuelcouldresultinmelting,fragmentation,anddispersaloffuel.Themechanicalactionassociatedwithfueldispersalmightbesuf-ficienttodestroyfuelcladdingandtherod-bundlegeometryandtoprovidesignificantpressurepulsesintheprimarysystem.TolimittheeffectsofCEAejection,RegulatoryGuide1.77recommendsthattheradially-averagedenergydepositionatthehottestaxiallocationberestrictedtolessthan280cal/g.C-Ehasadoptedthisenthalpylimit(Reference42).Evaluation-TheCEAejectionanalysismethodsusedbyC-EaredescribedintheNRCapprovedreportinReference42.TheCEAejectionanalysisforSt.LucieUnit2utilizesthemethodsinReference42.Ingeneral,themostlimitingassembliesinaCEAejectionaccidentarelowburnupassembliesbecausetheseassemblieshavethegreatestpowerandenthalpycapabilityinthecore.Themaximumenthalpiesforfuelatarod-averageburnupof60HWd/kgHwillbesignificantlyboundedbythelowburnupassembliesbecausepowercapabilityofthishighburnupfuelislow.Consequently,fuelatanextendedburnuplevelof60HWd/kgHisexpectedtoremainwe]lbelowthe280cal/glimit.PNLconcludesthattheanalysismethodsusedbyC-EforevaluatingtheCEAejectionaccidentare'acceptableforapplicationtotheC-E16x16fueluptoarod-averageburnupof60HWd/kgH.(C)CLADDINGBALLOONINGANDFLOWBLOCKAGEBases/Criteria-IntheLOCA-ECCSanalysesofCESSARplants,empiricalmodelsareusedtopredictthedegreeofcladdingcircumferentialstrainandassemblyflowblockageatthetimeofhot-rodandhot-assemblyburst.Thesemodelsareeachexpressedasfunctionsofdifferentialpressureacrossthecladdingwall.Therearenospecificdesignlimitsassociatedwithballooningandblockage,andtheballooningandblockagemodelsareintegralportionsoftheECCSevaluationmodel.PNLconcludesthatC-EadequatelyaddressesthisissueintheirLOCA-ECCSanalyses(Reference43).Evaluation-ThecladdingballooningandflowblockagemodelsusedintheC-ELOCA-ECCSanalysisdescribedinReference43aredirectlycoupledtothemodelsforcladdingrupturetemperatureandburststrain[discussedinSection3.0(C)].TheC-Ecladdingdeformation,rupture,andflowblockagemodelsusedinReference43arethesameasthoseproposedbyNRCinNUREG-0630(Reference46).PNLconcludesthatthesemodelsarenotaffectedbytheburnupextensionrequestedinthissubmittaland,therefore,Reference43remainsacceptableforapplicationtotheC-E16x16fueldesignuptoarod-averageburnupof60HWd/kgH.Thesteady-stateoperationalinputthatisprovidedtotheLOCAanalysisfromtheFATES3Sfuelperformancecode(Reference20)isburnupdependent.As20 ttnotedearlier[seeSection4'.0(G)j,theFATES3Bcodehasbeenverifiedagainstdatatorod-averageburnupsof62HWd/kgHandpreviouslyapprovedforextendedburnupapplicationtotheLOCAanalysisuptoarod-averageburnupof60HWd/kgH(Reference21).Therefore,PNLconcludesthatthiscodeisalsoacceptableforuseinprovidinginputtoLOCAanalysesoftheC-E16x16fueldesignuptoarod-averageburnupof60HWd/kgH.(D)STRUCTURALDAMAGEFROMEXTERNALFORCESBases/Criteria-TowithstandthemechanicalloadsofaLOCAoranearthquake,thefuelassemblyisdesignedtosatisfythestresscriterialistedinTable9-1ofReference44,andguide-tubedeformationislimitedsuchastonotpreventCEAinsertionduringthesafeshutdownearthquake(SSE).Thesecriteriahavebeenfoundacceptable(Reference15)forcurrentburnupfuelandPNLconcludesthattheyareacceptableforC-E16x16fueldesignsuptoarod-averageburnupof60HWd/kgH.Evaluation-TheC-Emethodsusedtoevaluatethemechanicalloadsduetoacombinedseismic-LOCAeventaredescribedinReference44.Itisnotedthattheseismic-LOCAanalysesarenotaffectedbyanincreaseinrod-averageburnupupto60HWd/kgMand,therefore,previousboundingseismic-LOCAanalysesremain.applicableatthisburnuplevel.ThisreporthasbeenapprovedbytheNRCforcurrentburnuplevelsandPNLconcludesthatitremainsapplicablefortheC-E16x16fueldesignuptoarod-averageburnupof60HWd/kgH.

6.0CONCLUSION

SPNLhasreviewedSt.LucieUnit2/C-E'srequest,assubmittedinReference1,toextendtheburnupleveloftheC-E16x16fueldesigntoarod-averageburnupof60HWd/kgMinaccordancewiththeSRP,Section4.2.PNLconcludesthatthisrequestbySt.LucieUnit2asdescribedinReference1isaccep-table'orlicensingapplicationsoftheC-E16xl6fueldesignuptoarod-averageburnuplevelof60MWd/kgH.However,PNLrecommendsthatfuturerequeststoextendtherod-averageburnuplimitbeyond60HWd/kgMshouldbeaccompaniedwithcorrosion,claddingstrain,andyieldandfracturestrengthdataattheextendedburnuplevelsrequested.Thesedataarenecessarytosupporttheirradiationofhigherburnupfuelbeyond60HWd/kgM.7.0REFERENCES1.CombustionEngineering,Inc.November1989.VerificationoftheAccetablitofa1-PinBurnuLimitof60HWdkforCombustionEnineerin16x16PWRFuelforSt.LucieUnit2.CEN-396-P,CombustionEngineering,Inc.,Windsor,Connecticut.2.CombustionEngineering,Inc.June1989.VerificationoftheAccetabilitofa1-PinBurnuLimitof60MWdkHforCombustionEnineerin16x16PWRFuel.CEN-386-P,CombustionEngineering,Inc.,Windsor,Connecticut.21 3.5.6.LetterfromS.R.Petersen(U.S.NuclearRegulatoryCommission)toN.Cams(ArkansasNuclearOne)regarding"SafetyEvaluationbytheOfficeofNRRRelatedtoAmendmentNumberilltoFacilityOperatingLicenseNumberNPF-6,"datedNovember27,1990.U.S.NuclearRegulatoryCommission.July1981."Section4.2,FuelSystemDesign."InStandardReviewPlanfortheReviewofSafetAnalsisReortsforNuclearPowerPlants--LWREdition.NUREG-0800,Rev.2,U.S.NuclearRegulatoryCommission,Washington,D.C.UnitedStatesFederalRegister."AppendixA,GeneralDesignCriteriaforNuclearPowerPlants."In10CodeofFederalReulationsCFRPart50.U.S.PrintingOffice,Washington,D.C.UnitedStatesFederalRegister."ReactorSiteCriteria."In10CodeofFederalReulationsCFRPart100.U.S.PrintingOffice,Washington,D.C.7.8.9.UnitedStatesFederalRegister."AcceptanceCriteriaforEmergencyCoreCoolingSystemsforLightWaterNuclearPowerReactors."In10CodeofFederalReulationsCFRPart50Section50.46.U.S.PrintingOffice,Washington,D.C.LetterfromC.Poslusney,Jr.(U.S.NuclearRegulatoryCommission)toJ.J.Fisicaro(ArkansasNuclearOneUnit2),datedApril2,1990.LetterfromJ.J.Fisicaro(ArkansasNuclearOneUnit2)toU.S.NuclearRegulatoryCommissionDocumentControlDesk,datedHay3,1990.

Enclosure:

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Mr.J.H.GoldbergFloridaPower5LightCompanySt.LuciePlantCC:JackShreve,PublicCounselOfficeofthePublicCounselc/oTheFloridaLegislature111WestMadisonAvenue,Room812Tallahassee,Florida32399-1400SeniorResidentInspectorSt.LuciePlantU.S.NuclearRegulatoryCo'mmission7585S.HwyA1AJensenBeach,Florida33457Mr.GordonGuthrie,DirectorEmergencyManagementDepartmentofCommunityAffairs2740CenterviewDriveTallahassee,Florida32399-2100HaroldF.Reis,Esq.Newman5Holtzinger16]5LStreet,N.W.Washington,DC20036JohnT.Butler,Esq.Steel,HectorandDavis4000SoutheastFinancialCenterMiami,F1orida33131-2398AdministratorDepartmentofEnvironmentalRegulationPowerPlantSitingSectionStateofFlorida2600BlairStoneRoadTallahassee,Florida32301Mr.JamesV.Chisholm,CountyAdministratorSt.LucieCounty2300VirginiaAvenueFortPierce,Florida34982Mr.CharlesB.Brinkman,ManagerWashingtonNuclearOperationsABBCombustionEngineering,Inc.12300TwinbrookParkway,Suite330Rockvilie,Maryland20852Mr.JacobDanielNashOfficeofRadiationControlDepartmentofHealthandRehabilitativeServices1317WinewoodBlvd.Tallahassee,Florida32399-0700RegionalAdministrator,RegionIIU.S.NuclearRegulatoryCommission101MariettaStreetN.W.,Suite2900Atlanta,Georgia30323Mr.R.E.GrazioDirector,NuclearLicensingFloridaPowerandLightCompanyP.O.Box14000JunoBeach,Florida33408-0420