ML19226A334
| ML19226A334 | |
| Person / Time | |
|---|---|
| Site: | Nuclear Energy Institute |
| Issue date: | 08/14/2019 |
| From: | Holtzman B Nuclear Energy Institute |
| To: | John Marshall Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML19226A334 (7) | |
Text
BENJAMIN HOLTZMAN Senior Project Manager, Fuel and Radiation Safety 1201 F Street, NW, Suite 1100 Washington, DC 20004 P: 202.739.8031 bah@nei.org nei.org August 14, 2019 Ms. Jane E. Marshall Director, Division of Safety Systems (Acting)
Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555-0001
Subject:
Comments on Draft Interim Staff Guidance on the Chromium-Coated Zirconium Alloy Fuel Cladding Accident Tolerant Fuel Concept Project Number: 689
Dear Ms. Marshall:
On behalf of the nuclear energy industry, the Nuclear Energy Institute (NEI)1 submits the attached comments on the draft Interim Staff Guidance (ISG) on the Chromium-Coated Zirconium Alloy Fuel Cladding Accident Tolerant Fuel Concept (ATF-ISG-01). NEI has been working with the Nuclear Regulatory Commission (NRC) to establish regulatory guidance that may be used by NRC staff reviewing industry applications involving chromium-coated zirconium alloy clad fuel products. The ISG also provides insights on staff expectations for vendor topical submittals for accident tolerant fuel (ATF). This ISG supplements the guidance in NUREG-0800, Standard Review Plan. We appreciate the staffs early publication of the draft ISG and the opportunity to present our initial views of the document during the public meeting on August 6, 2019.
The attachment represents our initial comments based on a short timeframe review.
While there are several areas of agreement, as noted in our comments, the attachment highlights key differences between industrys and NRCs expectation for how the ATF coated cladding applications should be assessed. Additionally, we would like to reiterate one main concern related to the inclusion of the manufacturing process into the ISG that was discussed in industrys presentation at the public meeting.
Industrys concern is that the draft ISG significantly expands the traditional licensing scope and attempts to regulate the manufacturing process through fuel qualification. NUREG-0800 is a performance-based standard and the manufacturing process is not part of the current regulations. Furthermore, the coated cladding fuel concepts are not conceptually different from the current fuel products (same base substrate 1 The Nuclear Energy Institute (NEI) is responsible for establishing unified policy on behalf of its members relating to matters affecting the nuclear energy industry, including the regulatory aspects of generic operational and technical issues. NEIs members include entities licensed to operate commercial nuclear power plants in the United States, nuclear plant designers, major architect and engineering firms, fuel cycle facilities, nuclear materials licensees, and other organizations involved in the nuclear energy industry.
Ms. Jane E. Marshall August 14, 2019 Page 2 material with a 10-30 µm thick coating) and as such, the existing manufacturing oversight framework is considered to be adequate. Other NRC regulations and oversight, such as 10 CFR Part 50 Appendix B and vendor quality assurance inspections, are in place to review the manufacturing process. Therefore, manufacturing processes should not be included in the ISG as part of the staffs fuel qualification review.
Thank you for your consideration of our comments. We look forward to continue working with the NRC through the ISG publication process and industrys ATF activities as we work to deploy batch reloads by 2023. If you have any questions or require additional information, please contact me.
Sincerely, Ben Holtzman Attachment c:
Andrew Proffitt, NRR, NRC Jason Drake, NRR, NRC Josh Whitman, NRR, NRC Dennis Morey, NRR, NRC Robert Lukes, NRR, NRC NRC Document Control Desk
Comment#
Location Comment ProposedChange 1
General AlthoughthisISGmainlyfocusesonthemetallicchromiumcoatingsonZirconium basedcladding,atsomeplacesNRCtriedtoincludesomediscussiononchromium basedceramiccoatingsandemphasizedtheirinfluenceonthepropertiesof underlyingbasecladding.Thisinclusionofdiscussiononceramiccoatingshasonly complicatedthereportandisnothelpful,sincemanythermophysicalpropertiesof theCrbasedceramiccoatedcladdingareexpectedtobesignificantlydifferentthan basecladdingandrequiressubstantialexperimentaldatafordevelopingmodelsand licensingjustification.
IndustryrecommendstoremovediscussiononCrbasedceramic coatingsandconsideronlymetallicCrcoatingforthisISG.Orbetter explainhowtheISGdenotesinformationapplicabletoanycoated claddingconceptandwhereinformationisonlyrelevanttoa specificcladdingconcept.
2 General IftheISGisintendingtospecificallydenotethephenomenaasbeingimportantfor coatingcladdingconcepts,theISGshoulddiscusstherelativeimportanceregarding theexistingphenomenaandnewmechanisms.Thecurrenttextequivocatesthe impactofallmechanismssuchasdefectsandembrittlement.Definingimportanceor concentrationofdefectsmayallowforimportantissuestobemoreeasilyseparated fromthenoise.
PleasereviseISGtexttobeconsistentwithintentandifspecifically denotingphenomenaasbeingimportantforcoatingcladding conceptsdenoteimportanceasperthePIRTreport.
3 General Theuseof'chrome'and'chromium'interchangeablyinseveralplacesisincorrect.
'Chrome'referstoamethodofindustrialelectroplating,nottheelementchromium Pleaserevisetexttoproperlyusechromeandchromium 4
MainSection Lines2326 IndustryappreciatestheabilitytoprovideinputontheISGbutwhatisthebenefitin notingthefeedbackmechanismintheISGitself?
Removeunnecessarytext 5
Main Document References ThepublicationdateforReference3appearstobeinerror.TheATFProjectPlan waspublishedinSeptember2018,notSeptember2019.
Pleaserevisetext 6
AppendixA Lines1833 TheISGcallsoutthatitisnotattemptingtosetstandardsforreviewofanycreditor benefitapplicantsmayrequest,butmanyofthephenomenanotedinAppendixCare specificallytiedtobenefitsandnotlicensingcriteria.
TheISGshouldclearlystatewhetherit'sdenotingthespecific contentneededforafueltopicalreportorprovidingadditional guidanceonhowindustrywillneedtorealizeprospectivebenefits.
7 AppendixA Lines3139 Theconfidenceleveltowhichtheproposedpropertyimprovementsmustbe demonstratedbytheapplicanttosatisfytheNRCreviewer(s)isnotexplicitlystatedin thedocument Pleaseincludeinformationrelatedtotherequiredconfidencelevel.
8 AppendixA Lines3439 Industryagreesthatbenefitsshouldbeallowedwhensupportedbydata,butplease indicatethatthedatamustsupportthe'fulloperatingdomain.'
Pleaserevisetextasshown:
"Finally,ifanapplicantwishestotakecreditforcoatingbehaviorup toacertainburnup,orduringcertainaccidentconditions,itis necessaryfortheadherenceofthatcoatingtothesubstratetohave beendemonstratedtothatburnupandduringthose conditionsjustifiedforthefulloperatingdomain."
9 AppendixA Lines3839 Thestructureofthesentencestronglyimpliesthathighburnupdataisa requirement.Thiscouldhaveimpactsoninitialimplementationsand/orconditional topicalapprovalsasthestatementimpliesthatcoatingsontherodsmustbe prototypicaltodemonstrateadherenceathighburnupbeforebatchloadingandthat itmaynotbepossibletouseallavailabledata.
Pleaserevisetextasshown:
"Finally,ifanapplicantwishestotakecreditforcoatingbehaviorup toacertainburnup,orduringcertainaccidentconditions,itis necessaryfortheadherenceofthatcoatingtothesubstratetohave beendemonstratedtothatburnupandduringthose conditionsjustifiedforthefulloperatingdomain."
10 AppendixA Lines5758 IndustryagreesthatSAFDLscanbeaddressedinmultiplewaysandthatnospecific testingrequirementsshouldbedenoted.
None 11 AppendixA Line70 Whatdoesthewordsufficientlyexactlymean?
Pleaseclarifytheexpectation.
12 AppendixA Lines6772 TheISGtextreferencesPIRTSection6.4.2andstatesthattheapplicantshouldensure theperformanceconcernsreferencedinthePIRTSectionareaddressed.ThePIRT sectionstatesthatalldata(forsomeperformanceconcerns)needtobeprovided fromtubesthatcomefromaqualifiedprocess.However,itdoesnotprovideany guidancetothereviewerastowhatitmeansforaprocesstobequalified.TheISG shouldbeclearthatitisnotregulationmanufacturingprocessesnorshouldbe requiringanapplicanttogetdatafromanapproved/qualificationprocess.
PleaserephrasetheISGtexttobeclearthatamanufacturing processdoesn'trequireNRCqualificationbeforedataacquisition canbegin.
13 AppendixA Lines6772 TheISGtextreferencesPIRTSection6.4.2andstatesthattheapplicantshouldensure theperformanceconcernsreferencedinthePIRTSectionareaddressed.ThePIRT sectionstatesthatalldata(forsomeperformanceconcerns)needtobeprovided fromtubesthataremanufacturedinaprototypicmanner.However,itdoesnot provideanyguidancetothereviewerastowhatitmeansforaprocesstobe consideredprototypic.TheISGshouldbeclearthatitisnotregulation manufacturingprocessesnorshouldberequiringanapplicanttogetdatafroman approved/qualificationprocess.
PleaserephrasetheISGtexttobeclearthatamanufacturing processdoesn'trequireNRCqualificationbeforedataacquisition canbegin.
Comment#
Location Comment ProposedChange 14 AppendixA Line7390 TheISGtextdiscussingthecurrent50.46regulatorylimit(1204°C/17%ECR)islikely inappropriateandneedstobecorrected.ThereferencedPNNLPIRTsection6.2.6 doesnotreallytalkaboutwhy1204°Cisnotappropriate.Thediscussiononwhy17%
ECRmaynotbeappropriateforacoatedrodappearstobebasedonmixupof calculatedECR(thatisregulated)withmeasuredECR(thatisnotregulated).Thefact thatthereisamismatchbetweencalculatedCPECR(orBJaccordingactual50.46) andmeasuredECRisareflectionoftheATFeffectivenessofthecoating.
TheargumentinISGappearstobethatforextendedtimeat1200°C(readthisto meanfortimesfarexceedingneededtoreachthelimitbasedoncalculated CP/BJECR,i.e.nolongerinDBAspace),thecoatedrodcouldbeembrittledeven thoughthemeasuredECRislow(becauseofATFbenefit);andbecausethe embrittlingmechanismisnotunderstoodthisbecomesaproblemandso17%ECRis notprotectingthecladding.Thisargumentonlymakessenseif50.46isbasedon measuredECR,butitisnot.Thecurrent50.46regulatorylimit,basedoncalculated ECR(CPorBJ)fromtimeandtemperature,actuallycontinuestoservethepurposeof protectingthecladding.
Thesectionshouldberevisedtostatethatcurrent50.46regulatory limit(1204°C/17%ECRforuncoatedcladding)canbeappliedona conservativebasistocoatedcladdingifsupportedbytestdata,and thatiftheapplicantwishestohaveadifferentlicensingcalculated ECRforthecoatedrod,thenjustificationmustbemade.Moreover thatnoexemptionto50.46wouldbeneededintheformercase, andanexemptionwouldbeneededinthelatteroption.
15 AppendixA Lines97101 Potentialregulatorychangesareintroducedrelatedtoextensionsoftheexistingfuel burnuplimits.Suchburnuplimitextensionsarecurrentlybeingevaluatedbythe industryandwerethesubjectofa2018workshopthatincludedNRCstaff.However, thiscommentseemsinappropriatefortheISGsinceburnuplimitchangeswerenot withinthereviewscopefortheATFPIRT.
Removeregulatorychangesforincreasingburnuplimitsfromthe ISGoncoatedcladding.
16 AppendixA Lines113115 "maybetoignorethecoating(forpurposesofTManalyses)andusetheproperties oftheunderlyingsubstrate">thiswordingcarriestheriskofnotconsideringwhere thecoatingresultsinachangedbehavior.Itcouldbeshownthatthecoatingdoesnot resultinmorethananegligiblechange,andthususethemodelofuncoatedcladding, butthatisnotignoringthecoating "maybetodemonstratethatthecoatingwillhaveanegligible impactonthepropertyandusethepropertiesoftheunderlying substrate."
17 AppendixA Lines115117 Industryappreciatesthatflexibilityisprovidedfortheapplicantinaddressingeach damagemechanism None 18 AppendixA Line138 theuseofthewordmayshouldbeclarifiedtoindicatethatthedescribedtestdata isoneofmanyoptionstosatisfythedataneeds.
Revisetexttoindicate"providesalistoftestdatathatmaycould beusedincodeassessment."
19 AppendixA Lines163166 Thisstatementpertainstogeometricuncertaintiesresultingfromfabrication.
Presumably,thiswillalsoapplytouncertaintiesincoatingthickness.
Pleaseclarifytheexpectation.
20 AppendixA Lines185187 IfcrackinganddelaminationofthecoatingareruledoutbyresultsfromtheLTA programandthesurfaceroughnessofthecoatedcladisshowntobesimilartothat fortheuncoatedclad,doestheapplicantneedtodoanyCHFtestingwithcoated cladding?
Pleaseclarifytheexpectation.
21 AppendixA Lines185187 andLines246 248 Theadditionofa30µmthickcoatingtoRFAfueldecreasesthehydraulicdiameterof interiorsubchannelsbylessthan2%[1.7%for30µmand1.1%for20µm].This shouldhaveanegligibleimpactonthethermalhydraulics.
Additionally,thestatementthatforAOOsandpostulatedaccidentsinvolvinga decreaseinreactorcoolantflowthepresenceofthechromiumcoatingwillnot changethesystemsresponseimpliesNRCsrecognitionthatthecoatingwillhave negligibleimpactoncorethermalhydraulics.Industryagreesthata1030µmcoating willhaveanegligibleimpactonTH.
PleaseensureconsistencyinISGregardingtreatmentofcoating impactonTH.Specifically,whethertheISGisindicatingthisasan importantareaforanapplicanttoaddressbecauseTHscopeisa topicinthetraditionalscopeoflicensingfueltopicalsorbecauseit's importanttocoatedcladdingapplications 22 AppendixA Lines221226 Thisparagraphpresumesthatmodels(TM,NuclearphysicsandTH)willbechanged tocapturetheimpactsofchromingcoating.Thisdoesnotacknowledgealternative approachessuchasignorethecoatingasdiscussedinLine113-115.
Recommendtochangeeachofthesentencestoshouldbe capturedconsideredinthe{fuelrodperformance/nuclearphysics/
thermalhydraulics}modelevaluation.
23 AppendixA, Lines249255 Thissectiondiscussesmanyexpectedbenefitsrelativetoadvertisedfeaturesofa generalproductasopposedtoprovidingguidancetoreviewthematerialchangesfor aspecificproductsubmission,whichmaylaterresultinbenefitsviatheincorporation toanalyses.ALOCAresult,suchasPCT,istheduetoawidevarietyofintegrated propertiesandphenomena.ApredictedPCTchangeshouldnotberelieduponsince itwillbeveryplantandproductspecific.
Additionally,thechangeinliberatedhydrogenshouldberestrictedtothereduced externalsurfacereaction.
ItissuggestedtheISGfocusonlythematerialchangesandtheir associatedspecificLOCAphenomenabenefit,e.g.reducedexternal reactionwithsteamreducesenergyreleaseandoxygengeneration andassociatedlossofductility;reducedoperationalhydrogen minimizeshydrogenenhancedembrittlement;etc.Anychangein resultswouldbejustifiedbythecombinationofchanges,positive ornegative,totheproduct.
24 AppendixA, Line251 ThetextsaysthattheparametersthatareaffectedduringLOCAarepresentedinthe tablebelow,howeverthedraftdoesnotcontainatablelistedbelow.Thisstatement shouldbecorrectedorthetableadded.
Pleaseprovidetableforreview.
Comment#
Location Comment ProposedChange 25 AppendixA Lines264268 StatementindicatesthatthescopeofworkneededtocompletetheChapter15 demonstrationincreasessignificantlyiftheapplicationisaccompaniedwith(among otherthings)anincreaseinallowablefuelrodburnuporincreased235Uenrichment.
Thisisablanketstatementthatneedstobeclarified.
TheideathattheChapter15SafetyAnalysesworkwouldincreasesignificantlyisnot consistentwithhowindustryconfirmssafetyanalysesonareloadandbounding analysisbasis.Onlyifthecoatedcladdingimplementationchangespartofthe boundingenvelopescurrentlyusedbysafetyanalyseswouldworkthenneedtobe addressed.However,theideathatasingleparameterdeviatingfromitsnoncoated valuewouldautomaticallySIGNIFICANTLYincreasetheChapter15safetyanalyses needsclarification.
NRCshouldexplicitlydefinetheadditionalscopeneededto completeChapter15analysesforcoatedcladdingapplications.
26 AppendixB Lines32,79, 8384 Industryrecognizestheimportanceofprocesscontrolsinmanufacturingbut disagreesthattheNRCshouldlicensespecificmanufacturingprocesses.TheISGand itsapplicationshouldfocusonthecriticalmaterialperformancecharacteristics, regardlessofthemanufacturingprocess.
Statementsconcerningprocessingconditionsand/orcoating techniqueshouldberemovedorrewritten.
27 AppendixB, Lines3940 Suggestaddingacaveattothestatement:"Table5.1inthePIRTreportprovidesa summaryoftheteststhatcouldbeperformedtoquantifythematerialproperties discussedbelowbutshouldconsidertheupdatedtextinthefollowingsections."
Pleaserevisetextasnoted.
28 AppendixB, Lines5985 ThermalexpansionsectionitisnotclearwhattheNRC'sexpectationsare.Arewe supposedtojustifythemodels/showdata?Addressthestressesfromthermal expansionmismatch?Somethingelse?
Justificationforthermalexpansionmodelsshouldbeprovidedas wellasademonstrationthatthermalcyclingdoesnotleadto coatingdamage.
29 AppendixB, Lines86101 IndustrybelievesthatCrcoatedcladdingwillhaveanimpactonemissivityby reducingoxidethickness-emissivitystronglycorrelatestooxidethickness,increasing withincreasedoxideuntilitstabilizesconsistentwithanopaquesurface.
Thereforetheimpactonemissivityvaluesshouldbeevaluatedand accountedforinaccidentanalysescommentalsoprovidedtoNRC forPIRTreportsection5.1.3.
30 AppendixB Lines131146 TheISGsaysthatthecoatingwillnotresultinanyimprovementinthestrengthofthe substrate,andisalsoassumedtohavezeroloadbearingcapability.Thiswasnot unequivocallystatedinthePIRT.Ifsupportedbydata,Industrywantstoretainthe abilitytorealizebenefitsinthisareaandsotheISGshouldnotpreemptthematthis earlystage.
Pleaseremovestatement"Generally,coatingisassumednotto offeranyloadbearingcapability."
31 AppendixB, Lines173185 TheNRCdoesnotstatetheirexpectations.DotheywantFRgrowthdata?Evaluation ofstrainmismatchandresultingstresses?
Verificationofgrowthmodelswithinreactordataoracommitment tocollectdatacanbeused.
32 AppendixB Lines199202 Inreactordataisrecommendedforoxidationrate,includingcrackedspecimens.
Thisdoesnotseemnecessaryifonlyconservativeoxidationbenefitsareclaimed,and alsodoesnotseemnecessaryifotherexreactormeasuresaretakentoshowthatthe cracks(ifpresent)donotresultinaggressivecorrosionatedges.
Pleaserevisetexttoindicatethatifthecoatedcladdingwillbeas goodasorbetterthancurrentfuelproductsforoxidation,and industrycanprovidesupportingjustificationofthisfactitis conservativetousethecurrentoxidationratewithoutadditional testdata.
33 AppendixB Lines201202 inreactordatafromrodswithcrackedcoatingsbeevaluatedtoassessifthereis aggressivecorrosionatcracksorinterfacesismorespecificthannecessary.
Revisetexttostate"theinterfacebetweencoatedanduncoated regionsinreactorbeevaluatedtoassessifthereisaggressive corrosionatcracksorinterfaces 34 AppendixB, Lines236245 Corrosiontypicallyreferstotheoperationalprocess,notthehightemperature oxidationreaction.Additionally,whilethinningofthecladdingisimportant,high temperaturesteamoxidationresultsindiffusionofoxygenintothebetasubstrate whichisthemechanismforcladembrittlement.Itissuggestedthatthissectionbe clarified.
Itissuggestedthatthissectionbeclarified.
35 AppendixC Mostoftheitemsinthissectionarenotnewfailuremechanismsbutrather performancecharacteristicswhichneedtobeaccountedforinthecurrentfailure mechanisms.TheexceptionisC.4.9eutecticformation,whichinfactisanewfailure mechanism.Galvaniccorrosionisamorespecificexampleofcorrosionthatis requiredbyNUREG0800,S4.2tobefactoredintotheotherfueldamage mechanisms,butcouldbetreatedasanewdamagemechanism,sinceitconceivably coulditselfcauseafuelfailure.
None 36 AppendixC Line7 Thewordsitingshouldbereplacedwith"citing" Pleasereplacetextasnoted.
37 AppendixC Lines916 Itisnotclearhownonuniformityincoatingthicknesscouldleadtorodbow.Thetext maybeconfusingRodBowandChannelBowinBWRapplications.
Pleaseclarifythissection.
38 AppendixC SectionC.2 ThereisnoSAFDLlistedforDNBorCPR?Shouldbeincludedinthissectionand guidanceprovided.
Pleaseaddtextasnoted.
39 AppendixC Lines5367 ThereistoomuchpresumptionaboutwhathappensinCrcoatingsduetoacrackin theinitial,asbuiltcoating.Butthisisonlyadverseifcreditistakenforoxidationrate reductionpostballooningduringaLOCA.
Thisshouldbephrasedsothattheissueisaddressed,butnot assumingthatthere'sanadverseconsequence.
Comment#
Location Comment ProposedChange 40 AppendixC Line66 InthesamewayNRCshouldnotbelicensing/regulationthespecificmanufacturing process,theinspectionprocessesandcontrolsshouldnotbepartofthelicensing process.Itisincumbentonthevendortoimplementprocesscontrolsthatensure materialperformanceandpropertiesareconsistentwithwhatislicensed.
Pleaseremovetextitmaybedesirabletoaddcrackdetection criteria..
41 AppendixC Lines9495 Limitsshouldbeproposedthatprecludeenvironmentaldamagetotheprotective Cr2O3layercanbewrittenmoregenerally.
Pleaserevisetexttotheimpactofthecoatingandassociatedoxide layeronoxidation,hydriding,andcrudshouldbepredictedand evaluated.
42 AppendixC Line141 ReferencetoAppendixAisincorrectandshouldreferenceISGAppendixBsincethe originalPIRTtextcrossreferencesPIRTSection5.1 Pleasereviseasnoted.
43 AppendixC, Lines144 146 AppendixAlines213216referto10CFR50.46candDG1327aspotentialpositive impactoftheCrcoatingsrelatedtotheserequirements.Thisisinconsistentwithlines 144146whichstatesthatthisISGwillonlydealwithcurrentregulationsandstaff guidance.
Itissuggestedthatthissectionbeclarified.
44 AppendixC Line151152 ForBWRs,thisisnotactuallyanaccuraterepresentationofdryoutphenomena,noris itactuallyarticulatedthiswayinNUREG0800,Chapter4.4.
Pleaserevisethetext"Thisthermalmarginshouldnotbeexceeded fornormaloperationandAOOs."tobeconsistentwithlanguage currentlyinNUREG0800.
45 AppendixC Lines169177 ThisfailedtodrawanyparallelsbetweentheincoreZrfuelrodandtheexcore Inconelheaterroddifferences.Isthereanunderstandingthattheperformanceof thesetwoarethesame,andthatonlyacoating(whetheronZrorNibasedalloy)may influenceCHF?Also,CPRandCHFarenotequivalent,andthephysicsmayresultin sensitivitiesnotbeingthesamebetweenDNBRandCPRestimationsforcoatedrods.
IndustryrequeststhatNRCreviewtextforconsistency.
46 AppendixC Line181 AppendixAlines181-194appearstogiveapplicantsdiscretiontoappropriately accountfortheimpactofcoatingsonCHF,includingtheimpactofcoating degradation.Incontrast,AppendixCappearstorequireCHFtestingforeachcoating andassemblytyperatherthanallowingdiscretion.Inaddition,AppendixCappears tocastdoubtontheveracityoftypicalCHFtestingusingInconelassemblies.
Thetwoappendicesshouldbereconciledsothatapplicantshavea clear,crispunderstandingofexpectations.
47 AppendixC Line195 ReviseimpactontheuniformelongationrelativetothereferenceZrwithimpact onthepelletcladdingmechanicalinteractionrelativetothereferenceZr.
Pleasereviseasnoted.
48 AppendixC Lines197199 Ifthealternateapproachisfollowedandthecurrentlimitsareconcludedtobe acceptablethenRIAtestingonirradiatedmaterialoracommitmenttodososhould notberequired.
PleaserevisetexttoindicatethatRIAtestingisnotrequiredwith acceptablejustification.
49 AppendixC Lines200203 Industrybelievesthatcoatedcladdingwillbeasgoodasorbetterthancurrentfuel productsduringanRIA,andaslongasindustrycanprovidesupportingjustificationof thisfactitisconservativetousecurrentRIAassumptionsforacoatedcladdingRIA analysis.Assumingthatallrodswouldfailcreatesunnecessaryconservatism.
Pleasereviseasnoted.
50 AppendixC Lines243251 RatherthanrepeatingtheLOCAembrittlementtestingprogram,includingirradiated claddingtubesasproposed,alimitedsubsetoftestingonunirradiatedandpre hydridedtubesshouldbesufficienttoconfirmadequacyoftheexistinglimitsor reasonablenessofanewsetofconservativelimits.
Pleaserevisetexttoindicatethereareadditionalmethodsof attainingtestdata.
51 AppendixC SectionC.4 Thesubsectionshavestatementsaboutbasingaccidentbehaviorusingtheterm basedon.Thistermshouldberevisedtowithconsiderationofthepotential impact.
Pleasereviseasnoted.
52 AppendixC Lines307328 Coatingcrackingisn'tanewfailuremechanism;itdoesnotinherentlycausea claddingfailure,butchangesthebehaviortobeaccountedforwhenevaluatingother damagemechanisms Crackingofthecoatingisnotafailuremechanismitselfand shouldn'tbepartoftheISG'sperformancecriteria.
53 AppendixC Lines329357 Delaminationisnotanewfailuremechanismitself;itdoesnotinherentlycausea claddingfailure,exceptforthepotentialcreationofdebris,whichaffectsother systems.ItaffectsthefuelcladdingresponseintheOTHERfailuremechanismsand willbeincludedintheperformanceassessmentofthecladdingwhenevaluating otherfailuremechanisms Delaminationisnotafailuremechanismitselfandshouldn'tbepart oftheISG'sperformancecriteria.
54 AppendixC Line331332 Ingeneral,ceramiccoatingswillbemoresusceptibletodelaminationthanmetallic coatings.-thisstatementisnotconsistentwithotherplacesintheISGwhere metallicandceramiccoatingsarenotedasbeingdifferentinthatthisstatementdoes notprovidethereviewerreferencesfortheinformation.
ConsiderrevisingtostateMetallicandceramiccoatingsmay behavedifferentlyinthisregard.Orremove,asthereisnospecific assistancetotherevieweronthetopic.
55 AppendixC Lines386391 Animprovementwouldbetoaddthattheinterdiffusioncouldbeimplicitlyor explicitlyconsideredinthedevelopmentofSAFDLs.Forexample,ifmorelimitson timeattemperaturearesetsuchthatinterdiffusiondoesnotbecomelimiting,it wouldbeimplicitlycoveredandnothingfurtherwouldbeneeded.
Pleaserevisetexttoindicate"CrZrinterdiffusionshouldbe consideredeitherimplicitlyorexplicitlyinthedevelopmentoflimits on" 56 AppendixC Lines392417 ThecurrentISGtextindicatesthatCr51willcausethesourcetermforATFcoated claddingtobeworsethancurrentfuelproducts.WhileCr51isaradioisotopenot currentlypresentincurrentfuelproducts,thestatementthatthesourcetermwillbe morelimitingignoresthebeneficialcontributionsthemorerobustaccidenttolerant attributesoftheATFfuelconceptprovide.ThesourcetermisunrelatedtoSAFDLs, safety,orthePIRTdefineddamagemechanismsandperformanceconcerns.
TheISGshoulddirecttheapplicanttoreviewtheimpacttosource termholistically,anddeterminewhethertheATFsourcetermis morelimitingsourcetermorifthecurrentsourcetermvalues boundtheATFcoatedcladdingsourceterm.Inmanycases,the coatedcladdingapplicationwillbeasgoodasorbetterthancurrent fuelproducts,andifindustrycanprovidesupportingjustificationof thisfactitisconservativetousethecurrentvalueswithout additionaltestdata.
Comment#
Location Comment ProposedChange 57 AppendixC Line403406 TheISGassumestheimpactofirradiationwillhaveanegativeimpactonthestrength andductilityofthecoating;however,Itcouldalsoimprovepropertiesas cladding/coatingsystemscanbecomplex.
TheISGshouldsimplyadvisethereviewertoconsidertheimpact.
58 AppendixC Line440 ThereareothermethodsforobtaininggalvaniccorrosionpropertiesbesidesLTA examination.
Pleaserevisetexttoconsidertheimpact.
59 AppendixC Lines441449 Defectsarenotanewdamagemechanism.Theydonotinherentlycauseacladding failure,justasdefectsincurrentcladdingdonotinherentlycausecladdingfailure.
Theyarepartofthepropertiesinanycladdingorcoatingandwillbeincludedinthe performanceassessmentofthecladdingwhenevaluatingotherfailuremechanisms.
Defectsarenotafailuremechanismitselfandshouldn'tbepartof theISG'sperformancecriteria.
60 AppendixC Lines441449 Thequalityassurancestepsorprocessesassociatedwithmakingthecladdingshould notbelicensedaspartoftheproduct.Productlicensingisbasedoncomponentsthat arerepresentativeoftypicalmanufacturingprocessesandthevendorqualitycontrol processeswillbeestablishedtoidentifythepresenceofdefectsthatwoulddegrade theperformancebelowthelicensedperformancelevel.
Statementsconcerningprocessingconditionsand/orcoating techniqueshouldberemovedorrewritten.
61 AppendixC Lines450456 ThelowesttemperatureeutecticfortheCrZrsystemisnotedasoccurringat1332C, whichisnotedbeyondthecurrentDBAtemperaturelimitof1200C.Isthisbeing notedbecauseitisanimportantfindingforcoatedcladdingthatneedstobe addressedeventhoughitisbeyondtraditionallicensingscope?Oristhisbeing includedforfutureapplicationswhereindustrymaytrytoextendtheDBA temperaturerange?
Pleaseclarifytheexpectation.