ML21130A363
| ML21130A363 | |
| Person / Time | |
|---|---|
| Issue date: | 06/25/2021 |
| From: | Christopher Hanson NRC/Chairman |
| To: | Delauro R, Leahy P US Congress, US HR (House of Representatives), US SEN (Senate) |
| Orenak M | |
| Shared Package | |
| ML21155A171 | List: |
| References | |
| CORR-21-0043, SRM-OGC201228-2 | |
| Download: ML21130A363 (8) | |
Text
PREPAREDNESS FORACCIDENTTOLERANTFUELLICENSING, INCLUDING HIGHERBURNUPANDENRICHMENT A Report forthe Senate Committee onAppropriations andthe House Committee onAppropriations pSREG(ffDA09 co 2.
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4AAAC BytheU.S.Nuclear Regulatory Commission Enclosure
Introduction TheU.S.
Nuclear RegulatoryCommission (NRC) developed this report asdirected bythe explanatory statement accompanying theConsolidated Appropriations Act,2021(Public Law 116-260).The explanatory statement directed theNRCtoreport ontheNRC'spreparedness for licensingthe use ofaccidenttolerant fuel(ATF) with afocus onthose stepsthat arebeing taken bythe staff to ensure that theagency isprepared toreview theexpected licensing
- requests, including those forhigher burnup
- limits, andincreased enrichment levels.
Applicants aremovingforward withplans toseekapproval tobatch load' fuel assemblies with twoATFtechnologies (coated cladding anddopedpellets) that mayhavehigher burnup limits andincreased enrichment by the mid-2020s.
Theenrichment, fabrication, transportation, and useoftheATFfuel assembliesrequires NRClicensing review andapproval.
TheNRChas already received somelicensing action requests fortheuseofATF,including higher burnup limits andincreased enrichment levels.
The currentlist ofthese submittals andtheir approvals, ifapplicable, canbefound ontheNRC's ATF publicWebpage(Ref.
1).
TheNRCstaff assessed its regulatory framework andfound theexisting regulations and guidance aresuitable forreviews oftheATFconcepts (i.e.,coated cladding anddopedpellets) expected tobesubmitted inthenear-term.
TheNRC also considers theexisting regulatory framework tobegenerally acceptable for licensing fuel with increased enrichment (from 5to approximately 10percent uranium-235 byweight) andhigher fuelburnuplimits (from 62to75 gigawatt-days permetric tonofuranium (GWd/MTU),
rodaverage) inthenear-term.
While the NRC'sexisting regulations andguidance support thereviewof ATF licensing actions, requests forenrichment limits higher than5percent uranium-235 byweight will require license amendments andexemptions.
TheNRCwill continue tolook forways toenhance the regulatory framework through guidance andpossible rulemaking activities.
TheNRCcompleted orisperforming theactivities detailed inthis report to support theNRC's efforts tocomplete thelicensing ofATF,including higher burnup limits andincreased enrichment, inparallel withtheindustry's research anddevelopment efforts while maintaining reasonable assurance ofadequate protection ofpublic health andsafety, promoting the commondefense andsecurity, andprotecting theenvironment.
Accident Tolerant FuelProject Plan While theNRCisready toreview andlicense ATF,higher
- burnup, andincreased enrichment submittals under thecurrent regulatory framework, theNRCisalsotaking steps tomakeagency processes moreefficient andeffective.
TheNRChasdeveloped theATFProject Plan(Ref.
2) toprepare forreviews ofbothnear-term andlonger-term ATFdesigns.
TheProject
- Plan, revised inOctober 2019,addresses thecomplete nuclear fuel
- cycle, including fuel fabrication, fresh fuel transport, in-reactor requirements, andspentfuel storage andtransportation.
The NRCstaff engaged extensively withitsstakeholders inthedevelopment oftheplan, including licensees, nuclear fuel
- vendors, industry
- groups, nongovernmental organizations, and international counterparts, consistent withtheNRC'sPrinciples ofGoodRegulation and statutory requirements.
1A batch loadisthereplacement ofapproximately one-third ofthefuel assembles inthereactor coreafter each operating cycle.
The Project Planoutlines anewapproach tofuel licensing inwhichtheNRCengages with applicants earlierintheir research anddevelopment
- phase, inparttoidentify andresolve potential safety issues promptly.
TheProject Planalsoconsiders operational flexibilities that licensees may seekbaseduponATFdesigns.
Increased communication andengagement occuronmany
- fronts, includingroutine vendor status
- meetings, attendance atindustry conferences, and asignificant increase inthenumber andfrequency ofpresubmittal meetings.
Thesemeetings allow theNRCandstakeholders toexchange information andincrease the efficiency ofthe review process.
Additionally,theNRCholds meetings andissues communications tofurther support dialogue withstakeholders overspecific technical or administrative issues.One valuable setofmeetings isheldmonthly withtheU.S.Department ofEnergy(DOE).
Inthese meetings, DOEshares information onATFstatus andresearch, whichhelps theNRCstaff toanticipate whatreviews maybeneeded.
InApril 2021(Ref.
3),theNRCissued afinalreport baseduponinformation gathering activities including, phenomena identificationand ranking tables (PIRT) andsevenfuel performance literature reviews concerning near-termATF
- concepts, including spentfuel transportation and
- storage, andreactor operating andaccident conditions.
NRC-issuedATF-related documents canbefound ontheNRC'sATFpublic Webpage (Ref.4).
TheNRCisalsodeveloping orrevising existing codes tobeusedforindependent confirmatory calculations.
Theseconfirmatory calculations provide insight into fuel andreactor systems behavior aswell aspotential consequences oftransient and accident scenarios andthe identification ofrisk-significant factors.
TheNRCwill update itscodes asdataandinformation arereceived.
OtherGeneral Preparatory Activities TheNRCisactively involved intwoElectric PowerResearch Instituteindustry research frameworks/groups that arecoordinating research onATF,higher burnup, and increased enrichment limits.
Thefirst istheCollaborative Research onAdvanced Fuel Technologies (CRAFT) forLight WaterReactors.
ThesecondistheExtended Storage Collaboration Program.
Participation inbothofthese research frameworks/groups allows theNRC tobe better prepared toreview future licensing submittals duetoits heightened awareness of vendor plans andresearch activities andprovides theNRCtheopportunity tooffer feedback to stakeholders asappropriate.
TheNRCfrequently interacts withinternational counterparts andsubject matter experts through Nuclear Energy Agency(NEA) working groups-most notably theWorking GrouponFuel Safety-and through international cooperative research programs toexpand ourtechnical database andmaintain awareness ofrelevant policy andtechnical issues withATF.Some notable international activities include:
TheOrganisation forEconomic Co-operation andDevelopment (OECD)/NEA-supported Studsvik Cladding Integrity Project ledbyStudsvik inSwedenhasprovided dataonhigh burnup fuel andcladding performance during asimulated loss-of-coolant accident.
TheJapanAtomic Energy Agencyhasprovided dataonchromia dopedfuel performance during areactivity-initiated accident conducted initsNuclear Safety Research Reactor.
e TheNRCstaff participates intheCabri International
- Project, ledbytheInstitute for Radiological Protection andNuclear Safety
- inFrance, whichstudies thebehavior of nuclear fuel andcladding during reactivity-initiated accidents.
a TheNRCstaff isparticipating intheOECD/NEA's QUENCH-ATF project through which it obtains dataoncoated cladding behavior indesign-basis andbeyond-design-basis loss-of-coolant-accident conditions.
TheNRCstaff isparticipating intheOECD/NEA Framework for Irradiation Experiments that waslaunched tocontinue thespirit of international cooperation andhighly-leveraged accesstonuclear
- safety, fuels, and materials research that hasbeenlost withthe2018closure oftheHalden reactor in Norway.
Theseinternational research programs enhance theNRC'sunderstanding ofsafety significant fuel andthermal-hydraulic system behaviorandprovide valuable datatodevelop andvalidate independent models for the NRC's confirmatory analysis codes.
Coated
- cladding, dopedpellets,higher burnup limits, andincreased enrichments levels are expected tobethefirst setoftechnologies submitted toNRCforlicensing review.
Thenext sections describe theNRC's preparations foreachofthese technologies.
CoatedCladding Nuclear fuel vendors arecurrently researchingand testing fuel that usesazirconium alloy cladding with athin outer coating ofeither chromium or a proprietary material.
Thisthin coating isintended toprovide resistance tocorrosion andwear and additional operational flexibility for powerreactors.
TheNRChasnotyetreceived anyin-reactor topical reports orlicense amendment applications forbatch loads ofcoated cladding but hasactivelyengaged with stakeholders.
TheNRCisprepared toreview licensing submittals forcoated fuel rod cladding.
Togetready, theNRCcontracted withnuclear fuels experts fromDOE'sPacific Northwest National Laboratory (PNNL) toperform aliterature review(Ref.
5)ondegradation and failure phenomena related totheATFconcept ofchromium-coated fuel rodcladding andtoconduct aPlRT exercise onthetopic.
TheNRCthenpublished aninterim staff guidance (ISG) on thesubject (Ref.
6).
ThisISGisavailable forvendors toconsult inpreparing their topical report submittals, which should helptoreduce thepotential forschedule uncertainty anddelays caused by submitting incomplete documents forreview.
Withregard tolicensing thefront-end (i.e.,
enrichment, fuel fabrication, andfresh fuel transportation) andtheback-end fuel cycle(i.e.,
spentfuel transportation andstorage) for coated
- cladding, theNRCstaff hasreviewed theapplicable regulations andguidance andhasissued twoliterature reviews (Refs.
7and8).
Fromthese
- reports, theNRCdetermined that no additions ormodifications tothefront-end andback-end regulatory framework areneeded.
Therefore, theNRCisprepared toreview coated cladding front-end andback-end licensing actions consistent withtheagency's safety-and-security mission andinparallel withthe industry's efforts.
TheNRChasalready reviewed andapproved twosubmittals (Refs.
9and10) that allow fuel vendors totransport fresh fuel with coated cladding.
DopedPellets Fuelvendors areresearching andtesting fuelpellets that mixother materials, knownas
- dopants, into thepellet during themanufacturing process.
Thesedopants change thephysical properties oftheresulting fuel pellet withthegoalofproviding bothoperational andaccident condition benefits forpowerreactors.
- 3
The NRC hasalready reviewed andapproved twodopedpellet topical reports forboiling water reactor fuels (Refs.
11and12) andalicense amendment (Ref.
13),
andtheindustry iscurrently researching dopedpellets forpressurized waterreactor fuels.
Additionally, thestaff has reviewed NRC regulations andguidance forthefront-end andback-end licensing ofdoped pellets and determined that noadditions ormodifications areneeded.
Therefore, theNRCstaff ispreparedto review pressurized waterreactor dopedpellet submittals anticipated from vendorsTodate, the NRChasreviewed andapproved arequest (Ref.
9)that allows afuel vendor totransport fresh fuelwithdopedpellets.
Higher Burnup Thecurrent fuel burnup limits differ slightly amongfuel vendors andfuel
- products, butfuel assemblies aregenerally limited to a maximum rod-average burnup of62GWd/MTU.Thereare potential applicants interested inraising thislimit toaround 75GWd/MTUrodaverage.
Burnup limits arenotspecified inanyregulations, butinsteadareincorporated into powerreactor licenses onceapproved intopical reports.
Therefore, rulemaking isnotneeded inthis areaand thestaff will onlyneedtoreview topical reports andlicenseamendment requests inorder to approve increased burnup limits.
Thephenomenon called fuel fragmentation, relocation, anddispersal(FFRD) anditspossible resolutions areofsignificant interest totheNRC.FFRD isthe fragmentation offuel pellets due toexpanding fission gasbubbles under accident conditions.
Thehigher theburnup ofthefuel during accidents, thesmaller eachfuel fragment becomes.
These smallerpieces offuel may axially relocate within thefuel rodiftherodballoons outwardand may beejected into the reactor coolant flow iftherodbursts.
Thefuel vendors andlicensees mayaddress FFRDinthe licensing process toadopthigher burnup levels through modeling. Other possible methods for addressing FFRDarecurrently underdevelopment.
Tobeawareofthe progress inboth technical andlicensing areasofFFRD,theNRCstaff isencouraging fuel vendors tohave preapplication meetings ontheir licensing approaches toFFRD,which three vendors havedone todate.
TheNRCstaff expects additional preapplication meetings oncevendors have further refined their approaches.
Additionally, theNRC'sparticipation inCRAFTwill allow theagency tounderstand potential applicants' approaches tofilling datagapsandthenewapproaches to licensing requests that arebeing developed forFFRD.Finally, theNRCstaff isdeveloping a
research information letter that will summarize theNRCstaff's understanding ofavailable research information related toFFRDandhowtheinformation canbeusedtodefine conservative limits fortheextent offuel fragmentation during areactor
- accident, theamountof fuel that could potentially bereleased fromtherod,andtheimpact offragmentation onthe release ofgaseous radionuclides.
TheNRCstaff currently plans toissue theresearch information letter bylate 2021forusebystakeholders.
Inaddition totheProject Plan,theNRChasproactively reached outtopotential applicants on higher burnup limits through twoNRC-led public workshops.
- Thefirst, whichwasheldon July 30,2020,included anoverview ofhigher burnup limits andincreased enrichment levels for thepublic andanexchange ofinformation focusing onthecomponents ofaquality submittal.
During thefollow-up workshop onJune10,2021,theNRCdiscussed theproposed research information
- letter, theenvironmental aspects ofhigher burnup
- limits, andhigher burnup spent fuel storage andtransportation issues.
Thesetwoworkshops provided avaluable exchange of information withavariety ofstakeholders.
TheNRCstaff hasreviewed theregulations andguidance fortheback-end licensing ofhigher burnup fuel anddetermined that noadditions ormodifications areneeded.
Therefore, NRCis
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prepared toreview these expected submittals.
TheNRCdidnotneedtoreview theregulations and guidance forthefront-end licensing ofhigher burnup fuel
- because, fromthefront-end perspective, higherburnup fuel isnodifferent fromother fuel.
Increased Enrichment Asstated earlier in this report,theNRCconsiders theexisting regulatory framework tobe generally acceptable for licensing fuel withincreased enrichment levels (from 5toapproximately 10percent uranium-235 byweight) inthenear-term using license amendments andexemptions.
Amendments wouldbeneeded tochangetheenrichment limit inindividual
- licenses, and exemptions wouldbeneeded byeachlicensee that wishes toexceed theenrichment limits in theregulations.
Toefficiently support expected requests for increased enrichment
- levels, theNRCisexploring theregulatory
- options, including thepossibility ofinitiating arulemaking.
Specifically, theNRC ispreliminarily exploring whether a rulemaking toamendTitle 10oftheCodeofFederal Regulations 50.68, "Criticality accident requirements,"
whichplaces anenrichment limit of 5percent onfresh fuel orrequires acriticality monitor tobeinuse,wouldbecostbeneficial.
TheNRCisstill intheearly stages ofthis process and will continuetoexplore potential regulatory options focusing onenrichments upto10 percent, which istherangeofinterest currently being expressed bypotential applicants.
Enrichments upto20percent mayalsobe given someconsideration asthestaff looks atpotentialregulatory changes.Depending onthe level ofpreapplication activities andother tangible interestexpressed bypotential applicants, a
rulemaking could possibly becompleted consistent with theindustry's plans toseekapproval to batch loadfuel withincreased enrichment inthemid-2020s, and licensees could request exemptions until thecompletion oftherulemaking.
TheNRCwillcontinue togaugeinterest in pursuing higher enrichment levels andadjust itsefforts aswarranted.
A keyelement forlicensing increased fuel enrichment levels will bethe front-end ofthefuel cycle.
TheNRCstaff reviewed theregulations andguidance for front-end licensing for increased enrichment anddetermined that noadditions ormodifications areneeded.
Therefore, theNRCisprepared toreview front-end licensing actions forincreased enrichment levels and hasreviewed andapproved several licensing actions that serve aspreparatory steps to allow a fuel facility toachieve enrichments above5weight percent (Refs.
14and15).
Inaddition, the NRChasissued oneapproval (Ref.
9)that allows afuel vendor totransport fresh fuel rods with enrichments above5weight percent uranium-235.
Toensure that potential applicants understand theNRC'stimelines forreviewing front-end licensing actions forincreased enrichments, theNRCidentified enrichment facility critical path items forapproving batch loadings in2023anddiscussed theminapublic letter totheNuclear Energy Institute (Ref.
16).
Iron-Chromium-Aluminum (FeCrAI)
Cladding andLonger-Term Accident Tolerant Fuel Concepts TheNRCmonitors progress onthedevelopment ofFeCrAl cladding andlonger-term ATF concepts.
TheNRCstaff frequently engages withDOEandfuel vendors tounderstand the current status andfuture direction ofthese concepts.
TheNRChasnotyetbeenprovided withrelevant detailed schedules, specific physical characteristics, ortechnical datafromvendors forFeCrAl orother longer-term ATFconcepts.
- 5
The NRC staff has,however, begunpreliminary research toprepare forthesereviews andto determine whether, andtowhatextent, changes totheexisting regulatory framework maybe needed tolicense these ATFtechnologies.
Withuncertain submittal timelines forthese technologies, itwouldbepremature fortheNRCtoundertake moreintensive preparatory activitiesat this time.
Conclusion TheNRCcontinuesto maximize its preparednesstolicense near-term ATFtechnologies (i.e.,
coated cladding and doped pellets),higher burnup
- limits, andincreased enrichment
- levels, andisprepared toreviewrequested licensingactions forbatch loads.
TheNRCwill continue to engage withpotential applicants, licensees, andother external stakeholders toensurethat the appropriate steps aretaken sothat ATF, higher
- burnup, andincreased enrichment licensing reviews arebothtimely andcomplete, consistent withmaintaining reasonable assurance of adequate protection ofpublic healthand
- safety, promotingthecommondefense andsecurity, andprotecting theenvironment.
References 1
NRCATFPublic
- Webpage, "ATF-relatedLicensing Actions,"
https://www.nrc.gov/reactors/atf/licensing-actions.html.
2.
NRCATFProject Plan,Version 1.1,"Project Planto Prepare theU.S.
Nuclear Regulatory Commission forEfficient andEffective Licensing ofAccidentTolerant Fuels,"
October 2019(Agencywide Documents Access andManagement System(ADAMS)
Accession No.ML19301B166).
3.
NUREG/CR-7283, ERI/NRC 21-204, "Phenomena Identification Ranking Tables for Accident Tolerant FuelDesigns Applicable toSevere Accident Conditions,"
preparedfor theU.S.Nuclear Regulatory Commission byEnergy Research Inc.,April 2021 (ADAMS Accession No.ML21113A277).
4.
NRCATFPublic
- Webpage, "ATF-related Documents,"
https://www.nrc.gov/reactors/atf/related-docs.htmi.
5.
PNNL-28437, "Degradation andFailure Phenomena ofAccident Tolerant Fuel Concepts:
Chromium Coated zirconium Alloy Cladding,"
prepared fortheU.S.Department of Energy bythePacific Northwest National Laboratory, January 2019(ADAMS Accession No.ML19036A716) andPNNL-28437, Revision 1,June2019(ADAMS Accession No.
19172A154).
6.
ATF-ISG-2020-01, "Supplemental Guidance Regarding theChromium-Coated zirconium Alloy FuelCladding Accident Tolerant FuelConcept,"
January 2020(ADAMS Accession No.ML19343A121).
7.
PNNL-29773, "Fresh FuelTransportation ofAccident Tolerant FuelConcepts Chromium Coated zirconium Alloy Cladding,"
prepared fortheU.S.Department of Energy bythePacific Northwest National Laboratory, March2020(ADAMS Accession No.ML20134H981).
8.
PNNL-30451, "Spent FuelStorage andTransportation ofAccident Tolerant Fuel Concepts
- Cr-Coated zirconium Alloy andFeCrAlCladding,"
prepared fortheU.S.
- 6
Department ofEnergy bythePacific Northwest National Laboratory, March2020 (ADAMS Accession No.ML20274A250).
9.
Letter fromJohnMcKirgan, NRC,toTanyaSloma,Westinghouse Electric
- Company, LLC, "Revision No.12ofCertificate ofCompliance No.9297fortheModelNos.
Traveller STD, TravellerXL,andTraveller VVERPackages,"
September 15,2020 (ADAMS Accession No.ML20255A297).
- 10. Letter from John
- McKirgan, NRC,toTimothy J.Tate,Framatome Inc.,
"Revision No.11 ofCertificate ofCompliance No.9319,fortheModelNos.MAP-12andMAP-13 Transportation Packages,"
January10,2019(ADAMS Package Accession No.
11 Letter fromMirela
- Gavrilas, NRC, toJerald Head,General Electric-Hitachi, "Final Safety Evaluation forGeneral Electric Hitachi NuclearEnergy
- Americas, LLCTopical Report NEDC-33406P, Revision 2,'Additive FuelPellets ForGNFFuelDesigns' (TAC No.ME3082)"
November 9,2015(ADAMS PackageAccession No.ML15195A459).
- 12. ANP-10340P-A, Revision 0,Incorporation ofChromia-Doped FuelProperties inAREVA Approved Methods,"
Framatome Inc.,
May 2018 (ADAMS Accession No.
- 13. Letter fromAndrew Hon,NRC,toJohnA.Krakuszeski, DukeEnergy
- Progress, LLC, "Brunswick SteamElectric
- Plant, Units 1and2 Issuance ofAmendment Nos.299and 327toRevise Technical Specification 5.6.5b toAllowApplication ofAdvanced Framatome Atrium 11FuelMethodologies (EPID L-2018-LLA-0273),"
March6,2020 (ADAMS Accession No.ML20073F186).
- 14. Letter fromJacobzimmerman, NRCtoWyatt
Louisiana Energy Services
- Amendment 85,Change toLicense Condition 6band Enrichment Limit (Enterprise Project Identification Number L-2019-LLA-0264),"
- May19, 2020(ADAMS Package Accession No.ML20119A040).
- 15. Letter fromTyrone D.Naquin, NRC,toScott P.Murray, Global Nuclear Fuels-America, "Global Nuclear Fuel
- Americas LLC:Review oftheMinimum Margin ofSubcriticality forupto8Weight Percent Enrichment ofUranium-235 andAmendment16(Enterprise Project Identifier L-2020-LNS-0002),"
August 13,2020(ADAMS Package AccessionNo.
- 16. Letter fromKathryn M.Brock, NRC,toJanet R.Schlueter, Nuclear Energy Institute, "Preparing forEfficient andEffective Licensing ofAccident Tolerant FuelwithHigher Enrichment,"
August 26,2019(ADAMS Package Accession No.ML19235A261).
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