ML17037C366

Nine Mile Point Unit 1 - Letter Responding to the August 13, 1971 Letter Requesting Additional Information on the Partial Refueling Scheduled for September 19, 1971 and Enclosing Information on the Second, Third, and Fourth Questions

ML17037C366
Person / Time
Site:	Nine Mile Point
Issue date:	08/20/1971
From:	Brosnan T J Niagara Mohawk Power Corp
To:	Morris P A US Atomic Energy Commission (AEC)
References
Download: ML17037C366 (20)

Text

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QBV:CLASSIF:POSTOFFICEUREG.NOIDESCRIPTIONI(MuatBaUnC!aSaified) htrreoux'-13-7l 1tre+furnf.shing addiinfo(answers toquestions 2,364onthepartialrefueling ofWineBilePointreactor..anmers

'touestinasFILECODE:50-220REFERREDTODATE-24-7RECEIVEDBYDATE'""~'ue.1villbeSezeeeee~ytee ogFilesCompBance

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U.S.ATOMICENERGYCOMMISSION

• U.S.GOVERNMENT PRINTINGOFFICER~1071Ma4WeafodMAILCONTROLFORMFoRMAEGGESSI6-60I 00tIIFlfIkCg~~tVJIls'4 NIAGARAMOHAWKPOWERCORPORATION

,iII~JR fNIAGARA~)MOHAWKSYRACUSE, NEWYORK13202August20,1971eEf$/(p~,9COIIPII+@40gDr.PeterA,Morris,DirectorDivisionofReactorLicensing UnitedStatesAtomicEnergyCommission Washington, D.C.20545

DearDr.Morris:

ReguiatoI'Y FileCy.0-.220YourletterofAugust13,1971requested additional information onthepartialrefueling oftheNineMilePointreactorscheduled for,September 19,1971.Uponreceiptofthisletter,NiagaraMohawkimmediately initiated thepreparation ofaresponse.

Information requested onthesecond,third,andfourthquestions inyourletterofAugust13,1971isenclosed.

Thexesponsetoyourfirstquestion, concerning theconsequences ofpossibleloadingerrors,isinfinalstagesofpreparation andwillbeforwarded promptlyuponcompletion.

Verytrulyyours,,J.BrosnanVicePr~dentandChiefEngineerEnclosures DOCKETEDUSAECAUG281971DREGIIUITORY II-5MAILSECTIONDOCKET'LERK b3757 e'tJbg-t%s'vp',Ig;rj

~~RE:T.J.BrosnanAugust20,1971responsetoDr.P.A.MorrisAugust13,.1971letter.2.Question:

Inviewofthefuelfailuresexperienced todate,describemeasures~andprogramsyouareemploying orproposetoinstitute toprovideimprovedqualityofgadolinium-bearing fuelasfabricated and'naugmented surveillance ofthecorefuelduringoperations.'Answer:

Fuelfaj.lures experienced todatehavebeenattributed byGeneralElectric'to localized cladhydriding andtoaninfrequent occurence oftubingflaws.Thepresenceoflocalized cladhydriding hasbeenconfirmed byinvestigations ofdefective fuelremovedfromtheDresdenUnit2andKRB(Germany) reactors.

Fueldischarged fromtheDresdenUnit2reactorduringtheJune1970andMarch1971outageswasinspected byGeneralElectrictodetermine thenatureandextentoffueldefects.Core"sipping" wasusedtoidentifythebundlescontaining leakerfuelrods.Eachoftheleakerfuelrodswasdisassembled andindividually inspected byultrasonic andeddycurrenttechniques.

Theseresultsweresupplemented byvisualexamination ofselectedrods.Detailedhot-cellexaminations wereperformed on12selectedfuelrodstoestablish thenatureoftheXuelrod.defects.and,to.detexmine

.thecause.andtheconditions leadingtothedefects.Thisinvestigation revealedthecauseofcladperforations intheDresden2fueltobelocalized cladhydriding fromhydrogenous impurities introduced intotherodduringmanufacture.

Theinvestigation ofleakingfuelattheKRBreactorrevealedthepresenceoflocalized cladhydriding, andinfrequent incidence ofrodperforations duetotubingflawswasalsoindicated.

Thoughafewgadolinia rodshaveexperienced failure,thequantityisstatistically small,andnoneofthesefailureshavebeenattributed tothepresenceofgadolinia.

Qualitycontrolofgadolinium containing fuelrodshasbeendescribed inotherdocketsl.

Reloadfuel.fortheNineMilePointNuclearStationiscurrently beingmanufactured byGeneralElectricCompanyattheirNilmington manufacturing facilityinaccordance withanestablished qualitycontrolprogram.Systematic programshavebeencarriedoutbyGeneralElectricatthei(ilmington facilitytoeliminate anysourceofhydrogenous impurities incurrentproduction fuelandtoeliminate ordetectanytubingflaws,shouldtheyoccur.Allloadedfuelrodsarehotvacuumoutgassed justpriortofinalweldingtoeliminate anyhydrogenous'impurities.

The1.DocketSO-2S4;QuadCitiesStation,Units1and2;Amendment 9;pp.3-5.2-1

~~

Answer(Cont'd):

manufacturing stepsusedatNilmington forzircaloytubingmanufacture wererevisedtoeliminate causesoftubingflawsandincreased non-destructive testingstepswereaddedtothetubingfinalinspection, including increased frequency ofultrasonic inspection.

Asindicated inourletterofJuly27,1971,NiagaraMohawkengineers anditsdesignated agent,theNuclearAuditandTestingCompany,areconducting anindependent auditoXthequalityassurance programattheNilmington facilityduringthemanufacture ofNiagaraMohawksreloadfuel.AlsoasstatedinourletterofJuly-27,1971,acompletevisualanddimensional inspection ofallfuelwillbemadeatNineMilePointNuclearStationpriortoinserting thefuelintothe'eactor.

Duringnormaloperation ofthestation,parameters relatedtofuelperformance aremonitored inaccordance withtheNineMilePointNuclearStationTechnical Specifications.

Inadditionasurveillance programonBoilingNaterReactorfuelwhichoperatesbeyondcurrentproduction fuelexperience willbeundertaken asitbecomesavailable forinspection.

Thescheduleofinspections fortheleadfuelrodwithrespecttoexposure, linearheatgeneration rateandthecombination ofthesewillbecontingent upontheavailability ofthefuelasinfluenced

.by.plant.operating,and facility,requirements.

2~2 I,

RET.J.BrosnanAugust20,1971responsetoDr.P.A.MorrisAugust13,1971letter.Question:

YourJuly27,1971letterstatedthattheperformance ofgadolinium-containing fuelhasbeendemonstrated successfully inotherBNRs.andthatwehavereviewedsuchfuelforseveralotherfacilities.

Clarifyyourreferences tootherdocketstoindicatetheinformation thatisrelevanttotheproposedNMPoperation withgadolinium-bearing fuelasregardsgadolinium content,marginstofuelmeltingandclad.damage.duringsteady-.state and.transient operations, including uncertainties inpowerdistribution asafunctionofburnupandsimilarly themargin-to-fuel damageforcontrolroddropaccidentconditions.

Answer:Fuelcontaining variousconcentrations ofgadolinia hasbeenutilizedintheHumboltBay,Dresden1andBigRockPointreactors.

Theexperience withthisfuelhasbeenreportedtotheCommission ontheQuadCitiesStationDocket>.TheType.2reloadfuelproposedforNineMilePointcontainsGd203inconcentrations within.therangeofthisexperience.

TheCommission hasreviewedthe.use..of, gadolinium containing fuelsimilartoNineMilePointType2reloadfuelonthedocketsforDresden22andQuadCities>.TheGd203'oncentrations intheNineMilePointType2reloadfuelareless'thanthemaximumusedineitherDresden2orQuadCitiesfuel.Thelowerconcentrations usedinNineMilePointfuelresultinhigherlinearheatgeneration rates(LHGR),for theonsetoffuelmeltingandcladdamage(onepercentplasticstrain)thanthecorresponding LHGP.'sapplicable tothegadolinium containing fuelrodsinDresden2,asshowninTable3-.1.Bydesign,thegadolinium containing fuelrodsinbothDresden-2andNineMilePointwilloperateataLHGRlessthanorequalto14.0kw/ft3.Therefore, themarginsbetweensteadystateoperation andfuelmeltingandcladdamage(onepercentplasticstrai'n)areactuallygreaterforNineMilePointwhencomparedtoDresden2.Themarginstofuel.meltingandcladdamageforgadolinium-containing fuelarealsogreaterforNineMilePointthanDresden2foralltransients whichresultinthesamemaximumLHGRfortheU02fuelrodsbecauseofthehigherLHGR'scorresponding tofuelmeltingandcladdamageforNineMile.Pointfuel.1.Dockets50-254and50-265;QuadCitiesStationUnits1and2;Amendment 9,pp.3-5.2.Docket50-237;DresdenNuclearPowerStation,Unit2;TopicalReporttoDPR-19,"Modification 71-1Refueling".

3.Ibid2,pp.43-1

'Answer(Cont'd):

Themaximumexposuredependent localpeakingfactorcalculated fortheNineMilePointreloadfuelisapproximately 1.25andis,therefore, lessthanthedesignbasispeakingfactorof1.30.Amaximumpeakingfactorof1.27wascalculated forfuelcontaining gadolinium inDresden2".TheGd02concentration oftheNineMiloPoint.fuelisdifferent thanthatotheDresden2fuel.Becauseofthisdifference theminimumenthalpies atstartandendofGd202-002 meltingarosome20cal/gmhigherfortheNineMilePointfuel;agreatermarginisaffordedtheNineMilePointgadolinia fuelascomparedtoDresden25.4,ibid2,pp.6.s5.Docket50-237,DresdenNuclearPowerStation,Unit2,TopicalReporttoDPR-19,Supplement No.1,Table3.3-2

TABLE3-1LINEARHEATGENERATION RATESFOROPERATING, FUELMELTING,CLADDAMAGECONDITIONS NinehfilePoint6Dresden27Operating LHGR(kw/ft)UORod217.5Gd0-UORod23214.0Gd0-UORod23214.0OnsetofFuelMelting(kw/ft)21.519.517.3CladDamage(kw/ft)28.026.525.26.Docket50-220;Letter,NiagaraMohawk(T.J.Brosnan)toAtomicEnergyCommission (Dr.PeterA.Morris)datedJuly27,1971,pp.2-3.7.Docket50-237;DresdenNuclearPowerStation,Unit2;TopicalReporttoDPR-19,"h(odification 71-1Refueling";

pp.D-2.3-3

0Re:T.J.BrosnanAugust20,1971responsetoDr.P.A.MorrisAugust13,1971letter.4.Question:

Describeindetailtheeffectoftheproposedfuelonanalytical resultsobtainedfromthestudyyouareperforming inresponsetoourlettertoyoudatedJuly22,1971,concerning theAECinterimacceptance criteriafortheperformance ofemergency corecoolingsystems.Answer:Enrichment levelsofthereloadfuelareslightlyhigherthanthoseoftheinitialcorebundles.Inaddition, thereloadbundlesincorporate aburnablegadolinium poisonmixedwithuraniumoxideinfourfuel'rodsineachbundle.Thedistribution oflocalpeakingfactorsandchangesinpeakingfactorswithexposurearedifferent withthereloadbundles,thoughthemaximumdesignlocalpeakingfactorisnotincreased.

Thesedifferences affectdirectlytheresultsoftheloss-of-coolant accidentanalyses.

Theseanalyseshavebeenredoneforuseofreloadfuelatanypositioninthecore,including themostreactiveposition.

TheyindicatethattheresultsoftheanalysesfortheinitialcorefueldesignprovidedinourletterofAugust20,1971.tothe..Commission, remainthesame.forthereloadfuelexceptasindicated below.Thesame'single-failure eventsdescribed inourletterofAugust20,1971totheComission fortheinitialcorefuelwereusedinthereloadanalysesandthecompleterangeofpeakingfactors,fromthebeginning totheendofbundlelife,wasstudied.ResultsareshowninFigure4-1.Themaximumpeakcladtemperature ofthereloadedcoreoccursat10,000WD/T,eventhoughthehighestlocalpeakingfactorisnotthenatitsmaximum.Amaximumpeakcladtemperature of226SFwasobtainedfromthisstudyforthedesignbasisaccident; thecorresponding peakcladtemperature fortheworstcaseintermediate sizebreakis224SF.Cladembrittlement continues tobeavoidedforallbreaksuptoandincluding thedesignbasisaccidentsincethemaximumlocalcladdingoxidation islessthan7.0~oforthereloadcorecase.Thesedatacomparecloselytothosecalculated fortheinitialcorebundles.Thus,theNineMilePointreloadedcorewillcontinuetobeinconformance withtheCommission's InterimAcceptance Criteriawhenreloadfuelofthetypedescribed inourletterofJuly27,1971isemployedatanylocation-in thecore.OurletterofJuly27,1971alsodiscussed reconstitution ofinitialcorefuel.Thereconstituted bundleswillcontainfuelrodstakenfromotherinitialcorebundles.Eachreplacement rodwillbeofthesameinitialenrichment asthedefective roditreplaces.

Exposuredifferences betweendefective andreplacement rodswillbelimitedtovaluessuchthatthebundlepowerwillbeessentially thesameasfortheinitialcorefuel.4-1

Answer(Cont'd]:

Inparticular, replacement rodexposurewillbethesameorgreaterthanthatofthedefective roditreplaces.

Calculations willdetailtheexposurehistoryofeachfuelrodintheaffectedbundlesandexposuredifference willbecontrolled suchthatthereplacement rodorrodswillresultinthepeakcladtemperatures following aloss-of-coolant accidentthesameorlessthanthatcalculated fortheinitialcorebundledesign.4-2

~~

NINEMILEPOINTNUCLEARSTATION.2300.EFFECTOFFUELBUNDLEEXPOSUREONPEAKCLADDINGTEMPERATURE-RELOADFUELMaximumDesignBasisAccident22002IOOl-C5lD2000DIntermediate Breakl90000FIGURE4-I5000l0000FUELBUNDLEEXPOSURE(MWD/T)I5000

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