ML17264B072

Forwards Response to Questions from NRC Staff on Proposed Mod of Spent Fuel Storage Pool,Dtd 970331

ML17264B072
Person / Time
Site:	Ginna
Issue date:	10/10/1997
From:	MECREDY R C ROCHESTER GAS & ELECTRIC CORP.
To:	VISSING G S NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
TAC-M95759, NUDOCS 9710210233
Download: ML17264B072 (22)

Text

.CATEGORY1REGULATOINFORMATION DISTRIBUTION

'TEM(RIDS)ACCESSIONA'NBR:9710210233 DOC.DATE:

97/10/10NOTARIZED:

NOFACIL:50-244 RobertEmmetGinnaNuclearPlant,Unit1,Rochester GAUTH.NAME.;AUTHORAFFILIATION MECREDY,R.C.

Rochester Gas6ElectricCorp.RECIP.NAME RECIPIENT AFFILIATION VISSINGIG.S.

DOCKETI05000244I

SUBJECT:

Forwardsresponsetoquestions fromNRCstaffonproposedmodofspentfuelstoragepool,dtd970331.DISTRIBUTION CODE:AOOIDCOPIESRECEIVED:LTR JENCLJSIZE:I+TITLE:ORSubmittal:

GeneralDistribution NOTES:License Expdateinaccordance with10CFR2,2.109(9/19/72).

05000244ERECIPIENT IDCODE/NAME PD1-1LAVISSINGEG.

INTERN:FILECENTE/EMCBNRR/DSSA/SPLB NUDOCS-ABSTRACT EXTERNAL:

NOACCOPIESLTTRENCL11111111111111RECIPIENT IDCODE/NAME PD1-1PDNRR/DE/ECGB/A NRR/DRCH/HICB NRR/DSSA/SRXB OGC/HDS3NRCPDRCOPIESLTTRENCL1111111110110RDNNOTETOALLNRIDS"RECIPIENTS:

PLEASEHELPUSTOREDUCEWASTE.TOHAVEYOURNAMEORORGANIZATION REMOVEDFROMDISTRIBUTION LISTSORREDUCETHENUMBEROFCOPIESRECEIVEDBYYOUORYOURORGANIZATION, CONTACTTHEDOCUMENTCONTROLDESK(DCD)ONEXTENSION 415-2083TOTALNUMBEROFCOPIESREQUIRED:

LTTR13ENCL12 ANDROCHESTER GA9ANDEIECTRICCORPORATION

~89EASTAVENUE,ROCHESTER, N.Y14649-0001 AREACODE716546-2700ROBERTC.MECREDYVicepresident NuclearOperations October10,1997U.S.NuclearRegulatory Commission DocumentControlDeskAttn:GuyS.VissingProjectDirectorate I-1Washington, D.C.20555

Subject:

ResponsetoQuestions fromNRCStaffonProposedModification oftheGinnaSpentFuelStoragePool(TACNo.M95759)R.E.GinnaNuclearPowerPlantDocketNo.50-244Ref.(1):LetterfromG.S.Vissing(NRC)toR.C.Mecredy(RGGE),

Subject:

RequestforAdditional Information

-SpentFuelPoolModifications (TACNo.M95759),datedAugust25,1997.

DearMr.Vissing:

ByReference 1,theNRCstaffrequested additional information regarding theproposedModification oftheGinnaSpentFuelStoragePooldatedMarch31,1997.Enclosedareresponses toeachofthequestions submitted bytheNRCstaff.Veryrulyyours,RobertC.MecreJPO~'",fan97f02'f0233 97fOi0PDRADOCK05000244PPDRlllllllllllllllllllllllllllllllltlllllll Mr.GuyS.Vissing(MailStop14B2)SeniorProjectManagerProjectDirectorate I-1Washington, D.C.20555U.S.NuclearRegulatory Commission RegionI475Allendale RoadKingofPrussia,PA19406GinnaSeniorResidentInspector Mr.PaulD.EddyStateofNewYorkDepartment ofPublicService3EmpireStatePlaza',TenthFloorAlbany,NY12223-1350 U.S.NRCG.S.VissingA-1October10,1997uestionNo.1:Inthesubmittal youhaveindicated thatsomespentfuelrackswithBoraflex, usedpresently inthespentfitelpool(SFP),willberetained.

Althoughtheanalysisdescribed inthesubmittal wasbasedonaveryconservative estimation ofthedegreeofBoraflexdegradation duringitsexposureintheSFP,experience hasshownthatthisdegradation dependsonseveralfactorswhichmaybedificulttoestimate.

Forexample,maintaining lowsilicalevelintheSFPwatermayaccelerate degradation ofthepolymerwithconsequential higherlossonboroncarbide.Therefore, many,plantsinstituted surveillance programsconsisting ofinspection ofcouponsandlormeasurement ofsilicaconcentration intheSFPwater.Areyouintending tohaveaBoraflexsurveillance programinthererackedSFP?Ifso,describetheprogram.Ifnot,provideyourbasis.R~esense:RG&Ehascommitted tomonitorthereactivesilicalevelsinthespentfuelpoolonamonthlybasistodetectandevaluateunusualtrendsofabnormallevels(Reference 1).RG&Eiscurrently monitoring silicalevelsandwillcontinuethissurveillance afterreracking ofthespentfuelpool.BecausethespentfuelrackswithBoraflexdonothavecouponswhichwouldallowperiodicinspection, RG&EhasoutlinedinReference 1severalactionstomonitorthepotential forBoraflexdegradation.

Someoftheseactivities, asdescribed inReference 1,willcontinueafter.theproposedreracking ofthespentfuelpool.Ifthereareanyquestions regarding thisactionplan,pleaseprovidearequestforadditional information.

Reference:

11.I.etterfromR.C.Mecredy(RG&E)toG.S.Vissing(NRC),datedOctober24,1996;

SUBJECT:

RESPONSETONRCGENERICLETI'ER96-04,DATEDJUNE26,1996,ONBORAFLEXDEGRADATION INSPENTFUELRACKS.

U.S.NRCG.S.Vis'singA-2October10,1997uestion.No.

2:1nthenewfuelracks,boratedstainless steelpanelswillremainincontactwiththecomponents madefromaregularstainless steel.Becauseoftheslightlydiferentchemicalcomposition ofthesematerials, galvaniccellsmayforminaboricacidsolutionandthismaybeasourceofcorrosion.

Showthatthisphenomenon willnotcontribute toasignificant degradation ofthepoisonmaterial.

R~esoose:Theoretically, theuseofBoratedStainless Steel(BSS)panelsastheabsorbermaterialinSpentFuelStorageRacksisassessedasamuchmorebenigncondition thantheuseofporousaluminum-boron carbidepanels.Thelatter,whichareknowntohaveafargreaterpotential forchemicalreactionwiththepoolwaterundernormalpoolconditions, havebeenusedinSpentFuelStorageapplications inthepast.Inordertoverifythehypothesis thatBSSwillbeessentially inertunderpoolconditions, aseriesofcorrosion testshavebeenperformed underveryadverseconditions asdiscussed below.Corrosion testsofBSScouponsofvariousconfigurations andboroncontentswereconducted severalyearsagobyCarpenter Technology Corp.,Reading,PAundercontracttoEPRI.Theresultsofthesetestshavebeenpublished inEPRIReportTR-100784, June1992'.Thetestconditions were2000PPMboricacidat154'Fforanexposuretimeofsixmonths.The154'Ftesttemperature wasbasedonthemaximumallowable bulkpoolwatertemperature forspentfuelstoragepools.Specimenconfigurations includedsimpleimmersion,

creviced, air-purgedandgalvanically-coupled specimens.

Thegalvanically-coupled specimens consisted ofBSScoupledwithType304.Noneofthetwenty-six (26)simpleimmersion, crevicedorair-purgedspecimens exhibited anymeasurable weightchangewiththeexception ofonespecimenwhichhadbeenwelded.Twoofthethreegalvanically-coupled specimens exhibited averysmallweightloss,andthethirdnomeasurable weightchange.Minorrustingwasnotedonthegalvanically-coupled specimens.

Theresultsofthesetestsindicated thatBSSexhibitsexcellent corrosion resistance tospentfuelpoolwateratmaximumpooloperating temperatures.

Inadditiontotheabovetestsat154'F,elevatedtemperature corrosion testsofBSShaverecentlybeenconducted in2450PPMboricacidsolutionat239'Fusingarecirculating autoclave'.

Theselection ofthetesttemperature wasbasedonthehighestlocalpoolwatertemperature whichcouldoccurinanycellintheGinnaSFP(saturation temperature basedonminimumheightof23feetofwateroveranycell).TheBSSmaterialusedforthesetestswasASTMA887-89,GradeB,TypeB7with1.9%boron,whichisslightlyhigherthanthemaximumboroncontentof1.82%intheBSSmaterialintendedforuseintheGinnaSFP,andtherefore isconservatively representative oftheGinnamaterial.

Testspecimens included lU.S.NRCG.S.VidsingA-3October10,1997simpleimmersion (freecorrosion),

galvanically-coupled andartificially-creviced (ASTMG78-89)configurations.

Thegalvanically-coupled specimens includedBSScoupledwithType304LandwithZircaloy4.Specimens wereexposedfortotaltimesof30and60days(720and1440hours).Theresultsofthesetestsshowedthatallspecimens exhibited stable,passivebehaviorintheboricacidenvironment withverylowcorrosion rates.Theaveragecorrosion rateforthesimpleimmersion andcrevicedBSSspecimens was.0167MilsPerYear(MPY)and.0320MPY,respectively.

Theaveragecorrosion rateforthegalvanically coupledBSSspecimens was.033MPY.Thesecorrosion ratesindicatethatintheworstcasecondition (i.e.BSSgalvanically coupledto304LandZircaloy4atasustained watertemperature of239'F),thethickness lossovera40yearexposurewouldbeontheorderof1.3mils(.0013"),

orapproximately 1%ofthetotalthickness ofaBSSsheet.Theminimumrequiredthickness oftheBSSsheetmaterialfortheGinnaSFPrackswas2.5mm(.098")or3.0mm(.118"),depending onracktype.Theactualthickness ofthefinishedsheets,however,exceededtheminimumthickness byaconsiderable margin.Forthe2.5mmsheets,theactualthickness valuesmeasuredduringfinaldimensional checksonthesheets(eachsheetwasmeasured) wereintherange2.65mm-2.90mm(.104"-.114")andforthe3.0mmsheets,3.15mm-3.50mm(.124"-.138").Itcaribeseenthatalossofthickness duetocorrosion ontheorderof.001"-.002" ismuchlessthantheextramargininthickness intheplatesandtherefore doesnotresultinaviolation oftheassumptions inthelicensing report.Thelossofneutronabsorberthickness duetogalvaniccorrosion istherefore negligible andcannotleadtodegradation oftheabsorbermaterialbelowminimumdesigncriteria.

ItshouldbenotedthatexposureoftheBSSmaterialatsuchahightemperature (239'F)forprolonged periodsoftimeisanextremecondition whichdoesnotrepresent normalpooloperating conditions.

Theexittemperatures forlocalfuelbundlecooling,basedonboundingconditions, arewellbelowthetemperature of239'F.'saresult,thecorrosion ratesexpectedfromexposureoftheBSSpanelstonormalpooloperating conditions wouldbesignificantly lowerthanthoseattheelevatedtemperatures.

Thecorrosion ratesmeasuredintheelevatedtemperature tests,therefore, represent aboundingcondition.

~Reference 1.Smith,R.J.,Loomis,G.W.,Deltete,C.P.,BoratedtainlessSteelAlicationinSen-FieltoraeRacks,EPRITR-100784, Project2813-21,FinalReport,June1992,p.3-25.2.ATEATechnical Specification 2226.031.000, BoratedStainless SteelAlicatinin~FuelRack.

I'll+IIa,.5 U.S.NRCG.S.VidsingOctober10,19973.LetterfromR.C.Mecredy(RG&E)toG.S.Vissing(NRC),datedMarch31,1997;

SUBJECT:

APPLICATION FORAMENDMENT TOFACILITYOPERATING LICENSE,REVISEDSPENTFUELPOOLSTORAGEREQUIREMENTS.

ATTACHMENT:

R.E.GINNANUCLEARPOWERPLANT,SPENTFUELPOOLRERACKING, LICENSING REPORT,SECTION5.0,THERMAL-HYDRAULIC EVALUATION.

U.,S.NRCG.S.VissingA-5October10,1997uestionNo.3:Describetheinspection programofboratedstainless steelpanelsbeforetheirincorporation intothespentfuelracks.Re~once:~BackroundTheboratedstainless steelfortheGinnaSFPrackswasspecified asASTMA887-89,GradeB,TypeB6/B7withaminimumboroncontentof1.70%.Boratedstainless steel(BSS)heatswereelectric-furnace meltedandbottom-poured intoingotsattheBOHLER/UDDEHOLM meltfacilityinKapfenberg, Austria.Thesteelchemistry isbasedonType304stainless steel.Thecarboncontentisrestricted to.04%max.,andphosphorus, sulfur,andnitrogenarecontrolled atverylowlevels.Heatanalysesarecheckedbyextracting achillcastsamplefromeachmeltandanalyzing spectrographically priortopouringtheingots.TheheatanalysesforthefourheatsofmaterialmeltedfortheGinnaSFPracksarelistedinTable1.Ingotswerehot-reduced toslabs,andthenfurtherreducedbyhot-rolling tosheetsatBOHLERBlecheinHonigsberg, Austria.Therollingprocessconsisted ofreductions intheprincipal (longitudinal) rollingdirection toapproximately 10mmthickness, thenfurtherreduction bycross-rolling inthetransverse direction, andfinalrollingintheprincipal direction tofinalthickness.

Afterhotrolling,finishing operations wereperformed atBOHLERBleche,Murzzuschlag, Austria.Theseoperations includedrollerleveling, solutionannealing, surfacegrinding, lasercuttingtospecified sheetdimensions, andpickling.

Sheetproductwasdividedintolotsduringthefinishing operations.

Alotwasdefinedasproductfromoneheat,oneheat-treatment batch,andonethickness.

TheBSSmaterialfortheGinnaSFPconsisted ofeleven(11)lots.InsectionsandTestPerfrmedatBOHLERBlecheThefollowing inspections oftheBSSsheetswereperformed atBOHLERBlechepriortofinalacceptance ofthematerial:

~VisualInspection Bothsidesofeachsheetwerevisuallyinspected aftergrindingforthepresenceof U.S.NRCG.S.VidsingA-6October10,1997burrs,scratches, orothersurfaceblemishes whichmightinterfere withorcausedamagetofuelassemblies duringinsertion into,orremovalfrom,theracks.Suchsurfaceconditions weredressedbybuffingorlightsanding.~Dimensional Inspections Thelengthandwidthofeachsheetwasmeasured.

Thethickness ofeachsheetwasmeasuredatsixdifferent locations usingcalibrated micrometers.

~Mechanical Properties Ultimatetensilestrength, yieldstrength, elongation, andhardnessweremeasuredbydestructive tensiletestingonasamplecutfromonesheetfromeachlot.Theresultsofthesetestsallmeetthemechanical properties requirements ofASTMA887-89(seeTable2).Theexcellent ductility values(10%-16%,substantially abovetheminimumspecification requirement of6%)areindicative ofhomogeneous distribution offineboridesinthematerial.

ItshouldbenotedthatalthoughtheproductfullymeetstheASTMacceptance

criteria, therearenodesignrequirements formechanical properties ofBSSintheGinnaSFPapplication.

ChemicalAnalyses(Productanalysesbywetchemicalanalysis)

Productchemicalanalyseswereobtainedfromasamplecutfromonesheetfromeachheat.Inaddition, sampleswerecutfromonesheetfromeachlotandanalyzedforcarbonandboron.Boronanalyseswereperformed bydigestion ofthesampleintoaqueoussolutionandanalyzing byICP(Inductively CoupledPlasma).Theresultsoftheseanalysesarepresented inTable3.Allvaluesmeetthechemicalrequirements ofASTMA887-89TypeB6/B7.Allboronvaluesexceedtheminimumrequirement of1.70%;-It shouldbenotedthattheproductanalysesinTable3areinexcellent agreement withtheheatanalyses(Table1).ChemicalAnalyses(Boroncontentbywetchemicalanalysis)

Fifty(50)locations withinonesheetfromHeatC70780weresampledandanalyzedforborontoestablish thehomogeneity ofborondistribution withinonesheet.Thesevaluesallfellwithintherange1.78%to1.82%boron(meanvalue1.80%,standarddeviation

.0117%boron).ChemicalAnalyses(Boroncontentbywetchemicalanalysis)

Onesamplewascutfromeachof51sheetsselectedfromthetotalpopulation of380sheetsandanalyzedforboroncontent.Thenumberofsamplesselectedfromeachof 0~'r U.S.NRCG.S.VissingA-7October10,1997thefourheatsandtherangeofboronvaluesforeachsamplesetisasfollows:TotalSheets~amleSize%BoronHeatB00021HeatB04901HeatC70780HeatC707961382798013samples8samples20samples10samples1.75-1.77%

1.75-1.77%

1.79-1.81

%1.75-1.79%

~'EN-3NeutronAttenuation Measurements DescritionofJEN-3DeviceandTe.MehdTheJEN-3deviceisasolidstatedetectorwhichcontainsaCf-252source.Thedeviceisshapedlikeateapotwithahandle.Thefronthalfofthedeviceisthedetector, andthebackhalfcontainsthesource.Thehandleisapproximately 2feetinlength.Thedoseatthetopofthedeviceis30mrem/hour.

Theefficiency forneutronsisapproximately 0.1%.Atablewhichisusedtoreflectneutronsismadeofpolyethylene whichisapproximately 3"thick.Theboratedstainless steel(BSS)sheettobeanalyzedisplacedbetweenthedetectorandthetable.Theneutronswhichareemittedbythesourcepassthroughthestainless steelandarethenreflected backbytheplastictable.Theenergyoftheneutronsisalsoreduced.Thosethermalized neutronsareattenuated bytheboratedstainless steel.Thefewerthecountsrecordedbythedetector, thegreatertheboronloadingintheBSSsheets.Theboronloadingcalculations areinfluenced bythefollowing factors:a)Theactualpercentboron;b)Thethickness oftheBSSsheetmaterial; andc)Thepowersupplyforthedetector.

Initially, thepowersupplyforthedetectorwasasourceofsystematic error.Afterinvestigating theoperating principles oftheinstrument, thesourceoferrorwaseliminated anderroneous testresultsfromtheinitialmeasurements wereeliminated fromconsideration.

TheabilityoftheJEN-3instrument tofunctionproperlyisinfluenced byboththethickness oftheBSSmaterialandtheboronloading.Therelationship betweenthecountsrecordedbytheJEN-3detectorandboronloadingisanegativeexponential relationship.

Allcalibration curvesweredeveloped usinglog-logplots.

U.S.NRCG.S.VihsingA-8October10,1997InsectionProramCalibration Curve-Acalibration curveforthestatistical analysisofBSSwasdeveloped usingdestructive chemicaltestingandneutronalbedoanalysiswiththeJEN-3.TheresponseoftheJEN-3deviceasafunctionofboronloadinginBSSsheetsofvaryingboroncontentandthickness wasestablished usingdestructive chemicalanalysis.

Boroncontentrangedfrom1.2%to1.9%,andsheetthickness from2.0mmto3.5mm.Boronanalyseswereperformed byBOHLERatthecorporate chemistry laboratory inKapfenburg, Austria.Thickness wasmeasuredusingacalibrated ultrasonic thickness meter(calibration recordsforthemeterandtechnician trainingrecordswerereviewedandfoundtobesatisfactory).

TheJEN-3devicewasresponsecheckedonadailybasistoverifyinstrument operability.

Theserecordsweremaintained forreviewandapprovalduringallQAsurveillance activities performed byFTI,ATEA,orRG&E.Theresulting calibration curvewasanegativeexponential line(log-logplot)withacorrelation confidence ofapproximately 99.9%.2)Verification ofBoronContent-Theneutronattenuation characteristics ofallBSSsheetswasmeasuredatonerandomlyselectedlocationusingtheJEN-3device.Sheetthickness wasalsomeasuredattheexactlocationwheretheJEN-3measurement wastaken.Theboronloadingineachsheetwascalculated fromtheJEN-3measurement usingtheequationdeveloped fromthecalibration curve.Inordertoaccountforallofthestatistical errorsintheJEN-3measurement process,theminimumacceptable levelofboronforanysheetwasestablished as1.74%.Thisminimumlimitprovidesanadditional marginofsafetyinboronloading.With1.74%astheminimumacceptable calculated boronloading,thereisgreaterthan95%confidence thatnoBSSsheetscontained lessthan1.70%boron.Thislevelofconfidence providesamarginofsafetyinthecriticality calculations.

Neutronattenuation dataofallBSSsheets,asmeasuredbyJEN-3atonerandomlyselectedlocationineachsheet,wasreviewedbyanindependent statistical consultant retainedbyRG&E;JosephO.Voelkel,PhD.,Assistant U.S.NRCG.S.VidsingA-9October10,1997Professor ofStatistics attheCollegeofEngineering, Rochester Institute ofTechnology.

Hisconclusions, basedonbothparametric andnon-parametric tolerance intervals, confirmed theacceptance

criteria, described above.3)BoronHomogeneity

-Thirty-four (34)BSSsheetswererandomlychosenfromthetotalpopulation.

Aneutronattenuation measurement wastakenatfive(5)randomlyselectedlocations oneachsheetusingtheJEN-3device.Thissamplingplanwasinaccordance withtheinstructions ofASTM-E826, "Standard PracticeforTestingHomogeneity ofMaterials fortheDevelopment ofReference Materials."

Thickness measurements weretakenattheexactlocations wheretheJEN-3measurements weretaken.Thedatawerethenevaluated bystatistical testsasfollows:Ranges(maximumminusminimummeasuredvalue)werecalculated foreachofthe34setsof5JEN-3values.Thesewereplottedagainstthecalculated meanrangeand2-sigmavalues.Ifnovaluesfelloutsidethe2-sigmalimits,thiswouldbeoneindication ofhomogeneity withinthepopulation.

Thiswasindeedthecase;i.e.,allvalueswerewithin2-sigmalimits.AnalysisOfVarianceundertherandomeffectsmodelwasperformed onthedata.Residualmodeldiagnostics demonstrated arandomdistribution ofresiduals, indicating homogeneity ofborondistribution throughout theBSSpopulation.

Theseresultsstronglyindicatehomogeneity ofborondistribution throughout theBSSproduct.InsectionsandTestsPerformed bRochester GasA,ElectricCo~ChemicalAnalysisOverchecks (Boroncontentbywetchemicalanalysis)

Chemicalanalysisoverchecks onsamplesofBSSobtainedfromBOHLERwereperformed bytwoindependent commercial testinglaboratories intheUS.Theseanalyseswereobtainedtoprovideadditional confidence intheboronanalysesreportedbyBOHLER.Resultsofthesetestsarepresented inTable4.Theresultsofthetheseoverchecks indicatethattheboronanalysesreportedbyBOHLERarereliable.

~Metallographic Examinations U,S.NRCG.S.VissingA-10October10,1997Samplescutfromonesheetfromeachlotofmaterialinboththeprincipal andtransverse rollingdirections wereexaminedmetallographically.

Allspecimens werepolishedandetchedwithKallingsreagent.Themicrostructures inbothlongitudinal andtransverse cross-sections exhibitafine,'niform dispersion ofboridesinanaustenitic matrix.Noevidenceofbandingorsegregation arepresent.Theboridehomogeneity intheBOHLERmaterialcomparesveryfavorably withpublished microstructures ofGradeAmaterialproducedbypowderedmetallurgy methods'.

ualitAssurance

'OverihAdditional inspections wereprovidedaspartofQualityAssurance oversight.

Bohleractivities weresubjecttoqualitysurveillance bypersonnel fromtheBohler,ATEA,Framatome Technologies, andRochester Gas&ElectricQualityAssurance organizations.

Thisoversight providedindependent monitoring oftheBSSmanufacturing processandresultsofinspection activities atBohler.~

Reference:

1.Smith,R.J.,Loomis,G.W.,Deltete,C.P.,BoratedStainle.s SteelAlicationinen-FuelStoraeRack.,EPRITR-100784, Project2813-21,FinalReport,June1992,p.3-13.

U.,S.NRCG.S.VissingA-11October10,1997TABLE1HeatAnalsesCSiMnPSCrNiBNC70780C70796B00021B04901ASTMA887TypeB6ASTMA887TypeB7.021.331.13.013,00119.8912.501.81.018.029.341.06.012.00119.9612.641.76.021.020.551.18.009.00219.6913.181.76.027.013.421.21.008.00119.5013.211.75.015.08'5'.0'45'3'8.0 12.01.510'20.015.01.740817512Pl045103l18P12Q1751PI20.015.02.25Note1:MaximumvalueTABLE2Mechanical ProertiesH~eatL~otC70796290C70796314C70780287C70780282C70780313C70780288C70780289B00021221B00021223B04901224B04901222UTS~Y~EIonationHardness~SI~KSI~oin2"~Brinell94.766.412.319596.062.111.721999.165.312.220993.161.214.123994.755.310.622997.563.811.219995.956.716.823994.462.810.922497.261.812.222993.058.313.823495.366.112.3229ASTMA887-8975Min30Min6.0Min241Max U.S.NRCG.S.VissingA-12October10,1997TABLE3~d~CSiMnPSCrNiBNCB00021221B00021223B04901222B04901224C70780282C70780287C70780288C70780289C70780313C70796290C70796314.021.551.18.008.00319.713~1.020.009.431.21.007.00219.413~1.01.024.321.10.012.00119.812.4.023.023.023.023.025.331.06.012.00119.912.5.0251.75.0321.741.73.0161.761.76.0221.811,801.801.801.78.0281.78TABLE4BoronAnalsisOvercheck

~Heat~SheetC70780105C70780105C70780105Laboratory BohlerLedouxM&PLabs%Boron1.83%1.86%1.82%B0002191AB00021371AB0490111AB04901171ALedouxM8cPLabsLedouxMEcPLabs1.82%1.84%1.82%1.85%

U.S.NRCG.S.VilsingA-13October10,1997uestion¹4:Althoughtestswithboratedstainless steelhaveindicated thatintheSFPenvironment nomeasurable corrosion degradation takesplace,theimportance ofitsroleinreactivity controlintheSFPmakesitadvisable tohaveasurveillance programwhichwouldprovideadditional assurance thatatalltimestherewillbeenoughpoisonmaterialintheSFP.Areyouplanningtoinstitute suchaprograniinyourplant?Ifso,describetheprogram.Ifnot,provideyourbasis.~Resense:RG&Eplanstoinstitute asurveillance programforboratedstainless steel(BSS)intheSFPattheR.E.GinnaNuclearPowerStation.Acoupontreehasbeendesignedwhichconsistsof.a304Lstainless steelracktowhich36BSScoupons(8"longX6"wide)willbebolted.EachfaceandtheedgesofthecouponsareexposedtotheSFPboricacidenvironment.

Crevicesand304L/BSSgalvaniccouplesarecreatedonthetreeateachboltlocation.

ThecouponswereselectedsothatmaterialfromeachheatandlotofBSSsheetmaterialto,beusedaspoisonpanelsinthepoolarerepresented onthetree.Incomparison withsurveillance programsforotherneutronabsorbermaterials, thedesignandconstruction ofthecoupontreefortheGinnaSFPprovidesamoreaccuraterepresentation oftheactualexposureconditions ofBSSintheSFP.Thetreewillberemovedandinspected afterthefirst18-monthoperating cycle,andeverythreeoperating cycles(approximately 41/2years)thereafter.

Thecouponswillberemovedfromthetree,inspected visuallyforanyevidenceofcorrosion, andthickness measurements takenontheexposedsurfacesandinthecreviced/galvanically coupledareas.Thesemeasurements willbecomparedwiththeoriginalthickness measurements recordedforeachcoupontodetermine ifanymeasurable materiallosshasoccurred.

Inaddition, eachcouponwillbeweighedandtheweightscomparedwithoriginalweightstodetermine weightchange.Anyunusualsurfacecondition suggestive ofsignificant corrosion willbeevaluated usingappropriate analytical methods.

1~slirCg-~I' sAU.S.NRCG.S.Vi~singA-14October10,1997uestion¹5:Withalargernumberoffuelassemblies storedintheSFPitisexpectedthatmorecorrosion productsandotherimpurities willbegenerated intheSFP.Isthepresently existingpurtftcation systemadequatetohandlethisincreased amountofimpurities?

Provideyourbasis.Recense:Thecurrentpurification systemconsistsof:(a)astring-wound skimmerfilterforsurfacecleanliness, and(b)aspentfuelpoolmixedbedresinforliquidpurification.

Theresinbedpullsfromthebottomofthepoolforitscleaningprocess.Itisa15cubicfootmixedbedresinfiltration system.Thefrequency ofchange-out ofthesurfacefiltration systemiscurrently approximately onceeverytwoyears.Thisisasurfaceclaritymaintenance system.Theadditional fuelwillnotaffectitsoperating characteristics.

Thefrequency ofchange-out fortheresinsystemiscurrently onceperyear.Historical recordsfollowing the1985rerackprojectatGinnaStationshowednomeasurable increaseinthechange-out frequency.

The1985changewaslargerinitsworkscopethantheproposedmodification.

Atthattime,approximately 420cellswereadded.Bycomparison, theproposedmodification willincreasethestoragecapacityby305cellsin1998(anadditional 48storagecellsmaybeaddedinthefutureifneeded)~Itispostulated thattheupcomingrerackwillnotincreasethecleaningsystemchange-out.

However,thesystemwillbemonitored todetermine anychangestohistorical patterns.

Therefore itcanbeconcluded thatthecapacityofthepurification systemisadequateandcanabsorbtheadditional storagerequirements withoutsubstantially affecting currentplantmaintenance capability tohandleanyincreased amountofcorrosion productsandotherimpurities.

01'I/'hJFP