ML21314A531

Response to Nuclear Energy Institute Comments on Draft Version 1.2 of the Accident Tolerant Fuel Project Plan

ML21314A531
Person / Time
Issue date:	11/19/2021
From:	Joseph Donoghue NRC/NRR/DSS
To:	Ashkeboussi N Nuclear Energy Institute
Wentzel M
References
Download: ML21314A531 (30)

Text

November 19, 2021 Mr. Nima Ashkeboussi Senior Director, Fuel Cycle and Radiation Safety Programs Nuclear Energy Institute 1201 F Street NW, Ste. 1100 Washington, DC 20004

SUBJECT:

RESPONSE TO NUCLEAR ENERGY INSTITUTES COMMENTS ON DRAFT VERSION 1.2 OF THE ACCIDENT TOLERANT FUEL PROJECT PLAN

Dear Mr. Ashkeboussi:

By letter dated August 5, 2021 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML21221A130), the Nuclear Energy Institute provided comments on draft Version 1.2 of the Project Plan to Prepare the U.S. Nuclear Regulatory Commission [NRC] for Efficient and Effective Licensing of Accident Tolerant Fuels (ATF Project Plan). The comments provided in your letter were in addition to or to expand upon the industry comments provided during the July 22, 2021 public meeting to discuss draft Version 1.2 of the ATF Project Plan (ADAMS Accession No. ML21208A152).

Enclosed are the NRC staffs responses to the comments received during the July 22, 2021 public meeting, as well as to those comments included in the August 5, 2021 letter. The comment responses provide a discussion of how the NRC staff considered each comment prior to issuing the final Version 1.2 of the ATF Project Plan (ADAMS Accession No. ML21243A298).

As described within the ATF Project Plan, the NRC staff considers stakeholder engagement one of the key components in preparing to license the ATF-concept, higher burnup, and increased enrichment fuels. As such, the NRC staff appreciates the participation of and feedback from the Nuclear Energy Institute and other industry representatives during the update to the ATF Project Plan. The NRC staff will continue to look for opportunities to engage all stakeholders as the agency continues to prepare for the licensing of these fuels.

Sincerely,

/RA/

Joseph E. Donoghue, Director Division of Safety Systems Office of Nuclear Reactor Regulation

Enclosure:

As stated cc: Listserv

Responses to Industry Comments on Draft Version 1.2 of the Accident Tolerant Fuel Project Plan General Comments

1. NRC Should Thoroughly Review and Incorporate Industry Comments into this Revision As indicated by the responses to detailed comments that follow, the NRC staff has fully considered the industrys comments and has made updates throughout the ATF Project Plan, as appropriate.

2. NRC Should Prioritize Efforts to Generically Evaluate Environmental Impacts As discussed in the detailed comment responses, the NRC staff is developing a plan to perform a bounding analysis of the environmental impacts associated with the deployment of ATF technologies, the details of which will be made available to the public, once finalized.

3. The Project Plan Should be More Responsive to the Use of Risk-Informed Application The ATF Project Plan was revised to make clear that the NRC staff will continue to take a risk-informed approach to nuclear fuel licensing; however, the Project Plan is not intended to convey guidance on how to pursue risk-informed licensing of the ATF-concept, higher burnup, and increased enrichment fuels. The NRC staff continues to encourage vendors and licensees considering a risk-informed approach to engage early with the staff to identify and resolve the relevant technical and policy issues.

4. NRC Should Clarify its Inclusion of Doped Pellets Within Appendix A As described in the detailed comment responses, the NRC staff has revised the Regulatory Framework Applicability Analysis table (which was removed as Appendix A from the draft ATF Project Plan to allow the NRC staff to make additional changes) to clarify the inclusion of doped pellets, as appropriate. Although the NRC has previously licensed fuel with doped pellets, it is possible that the agency's current regulatory framework (i.e., guidance documents) may not be fully applicable to all future doped pellet concepts; therefore, the information in the doped pellets column will be retained.

5. NRC Should Clearly Indicate that the Project Plan is Not Regulatory Guidance As discussed in the detailed comment responses, the NRC staff agrees that the ATF Project Plan is not intended to convey regulatory requirements or guidance. The NRC staff has made revisions throughout the ATF Project Plan and the Regulatory Framework Applicability Analysis table to clarify that information that the information presented therein should not be interpreted as new regulatory requirements or guidance.

Enclosure

Detailed Comments Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Regarding the term N/A The ATF Project Plan is intended to Consequences in Tasks 3 and contain the agency's strategy to 4 in the PRA sectionadd how ensure that the staff is ready to the NRC plans to address expeditiously review applications for dispersal and consequences. ATF designs, higher burnup, and increased enrichment fuels and is not intended to convey guidance to the industry on how to address specific technical challenges associated with those applications. Consistent with the new paradigm described in the 1 Pages 9 and 10 plan, the NRC staff encourages vendors and licensees intending to propose a risk-informed approach to licensing these fuel types to engage with the staff early in the process to facilitate the identification and resolution of issues in a timely manner. No changes were made to the project plan to address this comment.

Recommend word search for N/A The NRC staff reviewed the use of "must" to ensure the use is the word "must" and similar wording intentional and reflects a in the project plan and Regulatory requirement (as opposed to Framework Applicability Analysis and 2 General allowing the industry to explore made revisions in those cases where other means of justifying a the action was not intended as a position). requirement.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action The project plan contains no Include more information in See response to Comment 1.

evaluation of risk informed fuel the document about the use applications such as the of risk informed applications Alternative Licensing Strategy for submittals and any described in [Electric Power special considerations for Research Institute] EPRI these types of submissions.

3002018457. [Regulatory Guide] (RG) 1.174 only provides broad guidance related to the evaluation of defense-in-depth and design margins without 3 General consideration of the relative risks of the proposed licensing change.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Section 7.3 notes the need to We encourage the NRC to The NRC staff is developing a plan to address environmental impacts begin the evaluation of perform a bounding analysis of the for increased enrichment and environmental effects of environmental impacts associated burnup applications and notes higher burnup/enrichment with the deployment of ATF that the staff may need to promptly on a generic basis technologies, such as the consider if it is possible to and incorporate this into the transportation of ATF-concept, higher generically evaluate the Project Plan. To maximize burnup, and increased enrichment General/Section environmental impacts. There is generic applicability, the fuels and wastes. As a part of this 7.3, Page 25, 4 a very clear environmental industry is prepared to share process, the staff will likely engage Additional benefit to deploying higher expected Burnup and stakeholders to seek input on Considerations burnup fuels including the ability Uranium Enrichment information that should be considered to support extended operating requirements for a range of as a part of that review. The NRC cycle lengths, reduced batch cycle energy plans and staff will make the details of the plan reload sizes, fewer fuel reactor types as needed. available to the public, once it has shipments, reduced uranium been finalized.

mining, and less spent fuel generated.

The document makes mention of Clarify NRCs definition of The NRC staff revised the wording to near-term and long-term burnup long-term or revise remove the link to near-term and thresholds. Industry considers terminology. longer-term ATF concepts.

both the move up to 68 [gigawatt-days] GWd and 75 GWd to be near-term activities achievable in 5 Page 5 the mid-2020s even if we may be implementing them sequentially.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action How does the risk informed What are the expectations - The NRC staff added an additional framework for applications within discussion on guidance discussion to clarify that agency's fuel licensing fit within the related to a risk informed existing risk-informed framework can improved fuel licensing technical basis may be what be used to support the licensing of paradigm? is warranted within this nuclear fuel. Consistent with the new section. paradigm described in the plan, the NRC staff encourages vendors and 6 Section 3.2, Pg. 9 licensees intending to propose a risk-informed approach to licensing these fuel types to engage with the staff early in the process to facilitate the identification and resolution of issues in a timely manner.

The described scope of a Clarify the project plan so PIRTs are not typically done in

[phenomena identification and that PIRT results related to response to a specific LAR; rather, ranking table] PIRT extends to approval for batch reloads they are meant to assess the most the full intended use of a given be segregated from those important phenomena for a particular ATF concept, not just its initial needed to credit enhanced concept or application and how well licensing application. This safety performance. This will those phenomena are understood.

approach may represent a wise limit the necessary industry The staff can then apply that use of NRC resources but and regulatory resources to knowledge to a particular LAR, Section 3.2.3. requires extrapolation to future, address phenomena that are whether that request attempts to 7 Page 10, last as yet undefined industry applicable to a given [license credit enhanced safety performance, paragraph applications. amendment request] LAR. or not. The NRC staff believes that it is worth anticipating the full, intended use of a concept to avoid unnecessary duplication of effort (e.g., conducting multiple PIRTs on the same topic). No changes were made to the project plan in response to this comment.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action This section outlines the need for Expand on this a little more See response to Comment 1.

high quality submittals to meet to include what a high review timelines with a footnote quality, risk-informed defining high quality. That licensing submittal would definition refers to quantities of look like and what quantities data. of data means.

8 Section 3.2.4.1 This section highlights the NRC should clarify the use The NRC staff deleted the text

[General Design Criteria] GDC, of exemptions for this space. because it was confusing and not noting that the intent of these necessary for the purposes of the Section 7, Pg. 23, principal design and performance project plan. Consistent with the new TASK 1: 10 CFR requirements should be satisfied paradigm described in the plan, the PART 50, 10 CFR even if verbatim compliance NRC staff encourages any vendor or PART 52, AND 10 cannot be met. licensee that may have concerns 9 CFR PART 100 about meeting a General Design REGULATORY Criterion or a plant-specific design FRAMEWORK, criterion to engage staff early in the INREACTOR development process.

PERFORMANCE Comment Commenter Location in Plan Comment NRC Response Number Recommended Action The NRC separates batch- Please clarify whether or not The NRC staff revised the text to loading of ATF from crediting this means safety clarify that, although submittals for safety enhancements of ATF and enhancements for ATF ATF designs have not yet requested states the staff anticipates that materials can be licensed in approval for the safety enhancements such changes will need to be the near-term. The NRC that these fuel designs could made to address batch loading should not co-mingle any potentially afford, future submittals before making changes needed gaps associated with the could seek and obtain those to credit the safety enhancement implementation of ATF and approvals.

of ATF in the licensing basis. any potential future requests The statement seems to be for safety enhancements.

indicating that the NRC will not be ready to review applications that also contain a request to credit the safety enhancements for ATF materials.

Section 7, under 10 Task 1, second paragraph Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Under Licensing Pathways we Provide additional The need for an exemption will be would like to see more information on the use of guided by the plant-specific licensing information in here and in exemptions in the licensing basis of a facility and the scope of the Section Appendix B that addresses the pathways and any staff request. The NRC staff has updated 11 use of exemptions in the considerations. the project plan to discuss potential 7.2/Appendix B licensing process and how the rulemaking activities related to the staff sees that as part of any ATF-concept, higher burnup, and submittal. increased enrichment fuels.

This section states each LAR Clarify this section for LTAs The extent of the NRC staff's review would need a full and, if applicable, provide evaluation of the environmental description and detailed analysis information on a graded impacts of a proposed action will be performed by the staff of the approach for LTAs with determined by the Commission's environmental effects of increased enrichment and regulations in 10 CFR Part 51 and the transportation of fuel and waste burnup. scope of the request. Consistent with to and from the reactor for these the new paradigm described in the Section 7.3, page higher enrichment and burnup plan, the NRC staff encourages 12 25 levels. Is this an expectation for licensees intending to pursue and

[lead test assembly] LTAs in LAR to install a lead test assembly to addition to batch reloads? If both, engage with the staff early in the is it possible to apply a graded process to facilitate the identification approach? and resolution of issues in a timely manner.

Section 7.3, The last sentence in Section 7.3 Editorial correction Typo corrected.

has a typo hav should be Pg. 6, under, 13 have.

Additional Considerations Comment Commenter Location in Plan Comment NRC Response Number Recommended Action This section discusses the NRC- Please provide additional Licensees pursuing LTA programs issued guidance letter relative to clarification on the regulatory should consider the guidance in the performing LTA programs under expectations for a higher NRC staffs June 24, 2019, letter 10 CFR 50.59. In preparation for enrichment, higher burnup regarding the treatment of regulatory higher enrichment and higher LTA program. issues associated with LTAs. Should burnup, it is recognized that an a licensee determine that prior LAR will be required to support approval of an LTA is necessary or such LTA programs. However, it that additional clarification is is not clear if a limited scope necessary, the NRC staff encourages higher enriched, higher burnup those to engage with the staff early in LTA program will require the process to facilitate the consideration of many of the identification and resolution of issues Section 7.4, Lead other regulatory items identified in a timely manner. Regarding adding 14 Test Assemblies within the Project Plan such as a additional detail to the project plan, revised Environmental the ATF Project Plan is intended to Assessment. contain the agency's strategy to ensure that the staff is ready to expeditiously review applications for ATF designs, higher burnup, and increased enrichment fuels and is not intended to convey guidance to the industry on how to address specific technical or regulatory challenges associated with those applications. As such, no changes were made as a result of this comment.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Industry intends to leverage the Project Plan should address That NRC staff is engaged Oak Ridge Report on utilizing the the need for coordination internationally (TRANSSC) and will existing certified packages for with foreign counterparts on continue to monitor the situation. As

[low-enriched uranium plus] LEU+ transport. necessary, the NRC staff will interact LEU+ transport with a future with the Department of submittal. The Project Plan Transportation, as that agency is the 15 Section 8.1.4.1 should address the need for NRC competent authority with respect to to collaborate with their foreign changes to International Atomic counterparts on the issue UF6 Energy Agency Safety Standards shipments greater than 5%. Series No. SSR-6, "Regulations for the Safe Transport of Radioactive Material."

Paragraph 1, second sentence Suggested edit: The NRC staff revised the discussion states Transportation of UF6 Transportation of UF6 to clarify that the transportation of Section 8.1.4.1, enriched to greater than 5 weight enriched to greater than 5 UF6 enriched to greater than 5 weight Page 33, under percent We believe this weight percent will require percent will require the design and Challenges for sentence is missing the word or the design and certification certification of new packages or the 16 Transportation of and and. The sentence should of new Packages or the modification of currently existing Uranium Feed describe the need for new modification of currently approved packages. Depending on Material and package designs or modifications existing approved packages the staffs safety findings, this may Unirradiated Fuel of existing designs and and an exemption include an exemption from the exemptions if moderator regulations.

exclusion credit is sought.

The introduction to Appendix A Added language along the Added a discussion that the should include a statement that lines provided in the Regulatory Framework Applicability this table is for informational comment. Analysis is for informational purposes General - purposes and does not and does not supersede any 17 Appendix A, Page supersede or create any new regulations or guidance and that the A-1 regulatory requirements, information presented should not be guidance, or NRC expectations. interpreted as new regulatory requirements or guidance.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action The intent of the Doped UO2 Clarify that this column is for The NRC staff has previously Fuel Pellets column is unclear. pellets above 5%, for pellets licensed doped pellet fuels; however, Industry already has chromia and expected to be used for it is possible that the agency's current General - gadolinium doped pellets higher burn- up, or both. regulatory framework (i.e., guidance 18 approved and in-service in US documents) may not be fully Appendix A reactors. None of the comments applicable to all future doped pellet can apply to fuel that has already concepts. As such, no changes were been approved. made in response to this comment.

Table A.1 provides a priority Provide estimated durations The NRC staff has added a (high, medium, low, [to be or timeframes associated discussion of the expected determined] TBD) for the various with the closure of near- timeframes for each of the priority actions identified for closure by term, medium-term and levels.

the NRC, and associated long-term actions.

expected time frame (near-term, medium-term, long-term) which General - tends to be inverse of the priority 19 Appendix A (meaning higher priority actions generally tend to have a more near-term expected closure). Are there estimated durations or time frames associated with the closure of near-term, medium-term and long-term actions?

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Under Columns Burnup to 68 EPRI can provide The NRC staff revised the entry to and Burnup to 75 it states NRC-[Office of Nuclear provide reference to the Informal Reason: Fragmentation induced Regulatory Research] RES Assistance Request closure

[fission gas release] FGR of high access to EPRI Technical memorandum and to state that burnup fuel may change Reports and associated Informal Assistance Request results

[maximum hypothetical presentations through the will be incorporated in Revision 1 of accident/loss-of-coolant accident] existing MOU Addendum on RG 1.183.

MHA/LOCA source term and ATF to increase timing of release. EPRI test understanding in this area. If results showed fragmentation desired by NRC and other does not significantly increase stakeholders, the EPRI fission gas release. results may also be discussed with subject Fragmentation reduces non- matter experts through the gaseous fission product release Fuel Performance and into the coolant in a 24-hour soak Testing Technical Experts in water. Group (FPTTEG) of the Collaborative Research on 20 A series of fission product Advanced Fuel release experiments with local Technologies for light-water burnup up to 78 GWd/[metric ton reactors (LWRs) (CRAFT) of uranium] MTU were framework.

conducted. Specimens sealed in capsules at different pressures were heated to LOCA temperatures and fission product release was measured. At approximately 20 bars of pressure, fuel fragmentation can be effectively prevented, even for fuel significantly above the perceived fragmentation threshold. The test results showed fission gas release from fragmented fuel is only slightly higher relative to non-fragmented Comment Commenter Location in Plan Comment NRC Response Number Recommended Action fuel of the same burnup but under higher pressure. Additional tests at even higher pressure, where fragmentation is suppressed in both cases, showed fission gas release can be further depressed and thus suggests fission gas release during a LOCA transient may be rod internal pressure dependent, i.e., less fission gas is released at higher rod internal pressure.

Some of the test capsules, along with the fuel debris, were filled with water to evaluate non-gaseous fission product release.

Test samples that severely fragmented released less non-gaseous nuclides into the water after a 24-hr soaking period. The lower release rate may be related to lower wettability of smaller particles, a phenomenon well documented in literature.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Under Columns Burnup to 75 If desired by NRC and other The NRC staff suggests that this be and Doped UO2 Fuel Pellets it stakeholders, these JAEA handled through the CRAFT states Reason: Fragmentation- results may be discussed by framework.

induced FGR of high burnup fuel subject matter experts pellet may change source term through the Fuel and Reactivity initiated accident Performance and Testing (RIA) transient fission gas Technical Experts Group release is not currently well (FPTTEG) of the Appendix A, Item quantified. Collaborative Research on

1. 3 on RG 1.183 Advanced Fuel and Non-LOCA 21 In the last 6 years, JAEA Technologies for LWRs steady- state and conducted several tests with fuel (CRAFT) framework.

transient burnup up 84 GWd/MTU (Ref.:

releases Udagawa, Yutaka, 2018 JAEA Fuel Safety Research Meeting, Mito, Japan, October 30-31, 2018). There is a steady trend of increased release with burnup, but no sudden jump above the perceived fuel fragmentation threshold.

Under Column 235U Enrichment Clarify what, if any, actions The NRC staff added additional Appendix A, Item beyond 5.0 wt% it states Note: are expected. language to clarify that the analytical

1. 3 on RG 1.183 With respect to Table 4, extent of procedure can be used in lieu of and Non-LOCA 235U enrichment in RIA empirical Table 4.

22 database unknown. This note steady- state and transient questions the applicability to releases Table 4 but no action is identified.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Under Column Burnup to 75 it If desired by NRC and other The NRC staff suggests that this be states Reason: FFRD as result stakeholders, these JAEA handled through the CRAFT of HBU and possible loss of results may be discussed by framework.

coolant geometry during RIA has subject matter experts not been well quantified or through the Fuel understood. Performance and Testing Technical Experts Group It has not been established high (FPTTEG) of the burnup fuel would fragment in the Collaborative Research on same manner in an RIA versus in Advanced Fuel a LOCA. Fuel fragmentation has Technologies for LWRs been reported in [Japan Atomic (CRAFT) framework.

Energy Agency] JAEA [Nuclear Safety Research Reactor] NSRR Appendix A, Item test of short pulse widths, but not 23

1. 5 on RG 1.236 clearly present in realistic longer pulse tests. The duration of the NSRR test does not allow enough time for gas to migrate out of the fuel while it is under compression. The short pulse also results in much higher temperatures in the outer radial locations of the fuel.

Fuel fragmentation is known to be suppressed by compressive stress and once the gas is released the driving force for fragmentation may no longer exist.

Item 5 in Table A.1 indicates that Revise language to indicate The language has been revised to high burnup RIA data is needed may be needed. Check for state, "may be."

Appendix A, Item with deposited energy beyond similarly used language 24

1. 5 cladding damage. However, if within the Appendix.

operating conditions result in deposited energy less than Comment Commenter Location in Plan Comment NRC Response Number Recommended Action cladding failure, then such data may not be required.

Under 235U Enrichment beyond This section and others The statement has been revised to 5.0 wt% it states that higher similar in nature should be indicate that increased enrichment enrichment will yield higher rod revised to replace could potentially lead to higher rod worth and higher peaking. This is enrichment with reactivity worth and peaking factors.

not necessarily true. Reactivity, where merited.

not enrichment, should be the figure of merit. This is because higher enrichment will be balanced with higher burnable Appendix A, poison. It is thus entirely credible 25 Items #5 and #17 that a 6% enriched assembly could be less reactive than a 5%

enriched assembly. The control rods, reactor power level, boron concentrations, and cycle energy requirements are not changing; thus, the assembly reactivities cant be changing meaningfully.

RIA (CRE and CRDA) analyses already specify rod worth limits.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Under Columns Burnup to 68 The information in this The NRC staff deleted the note that and Burnup to 75, the Project section should be based on referred to the draft regulation.

Plan is based on a Draft and revised to meet the (unapproved) regulation (50.46c). current regulatory Since the proposed draft requirements, not the draft regulation could be approved rulemaking.

Appendix A, Item prior to the implementation of 26 #6 on 10 CFR higher burnup fuel, including the 50.46 draft in the project plan is informative, however, there are no NRC actions identified that would bring this to closure consistent with the expected burnup implementation timeframe.

Under Doped UO2 Fuel Pellets, Provide clarification as The NRC staff removed the statement it is unclear what an exemption is needed. that an exemption to 10 CFR 50.46 needed for. The industry has will be needed for doped pellets and deployed doped pellets in changed applicability to fully operating reactors. applicable.

Appendix A, Item 27

1. 6 Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Under 235U Enrichment beyond Industry meeting the STS The NRC staff revised the entry 5.0 wt% it states TS 4.2.1 is should be adequate and this deleted the text stating, "pending fully applicable pending the should be reflected in the outcome of the following."

outcome of the following: NRC Project Plan.

and TSTF to discuss whether or not the term slightly in TS 4.2.1 Appendix A, Item includes fuels enriched beyond

1. 8 on Standard 28 5%. If industry is consistent with Technical

[Standard Technical Specifications Specifications] STS 4.2.1 and STS 4.2.1 is fully applicable to chrome-coated zirconium cladding and doped UO2 pellets it does not seem necessary to revise the Tech Spec.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Under Columns Burnup to 68 Provide additional The NRC staff anticipates performing and Burnup to 75, with regard clarification. assessments prior to the next revision to thermal conductivity of the RFAA table for those items in degradation (TCD) in Item #11, the table with closures categorized as closure is listed as TBD and is TBD. During this assessment, the green color coded to indicate staff will identify a suggested closure NRC has the action. When will approach and estimated timeframe for this be determined? Is the NRC those items. The NRC staff does not planning to expand on the cited plan on expanding on IN 2009-23.

Appendix A, Information Notice 2009-23?

Items #11 on 10 CFR Part 50 29 Appendix K &

1. 19 on NUREG-2121 Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Closure bullet in Item #11 states Clarification on what is The term "fuel particle" was intended indicates that industry has the meant by fuel particle, to refer to that portion of a fuel pellet action to determine the impact of review the wording for Item that has broken off from the main fuel particle transport and #19 to be consistent with pellet, exited the rod, and is now deposition in terms of coolability #11, and review Appendix A capable of being transported and criticality. Previous tests for consistency. throughout the coolant system and quantified a wide range of fuel possibly deposited. The word fragment/particle size (such as "particle" was initially used to refer to those done by Studsvik, Halden, this fuel pellet portion, and no attempt ORNL, etc.) so clarification on to make any delineation between a what is meant by fuel particle fuel fragment or a fuel particle was would be helpful. Item #19 has intended. Therefore, the text has this listed as only a Note but has been updated to refer to "fuel Appendix A, industry action to close so should fragment/particle."

Items #11 on this be reworded to say Closure 30 to be consistent with Item #11?

10 CFR Part 50 Appendix K There may be other instances of this throughout Appendix A so it is suggested that the NRC review for consistency.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Under Columns Burnup to 68 Replace Burnup Threshold The table has been updated to and Burnup to 75, a Burnup with Threshold. replace the term "Burnup Threshold" Threshold is used. While burnup with "Threshold."

is a key parameter in the determination of FFRD (namely fragmentation), other factors may be appropriate for an FFRD threshold. Numerous LOCA simulation tests have been performed, both in-pile and out-Appendix A, pile. While most of the tests show Items #11 on a burnup-threshold, some high 10 CFR 50 burnup fuel did not fragment and 31 Appendix K & thus other factors, such as pre-

1. 19 on NUREG- transient power and testing 2121 conditions, may be involved.

EPRI test results showed fission gas release occurs with and without fuel fragmentation.

Fission gas release is pressure dependent, with lower release while under pressure/before burst. It is not known if fission gas not released due to rod internal pressure would be released upon rod burst.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action For the discussion of 10 CFR Provide clarity. Clarified that the recommendation 51.21 environmental assessment applies to the first LAR for a 10 CFR versus 10 CFR 51.22 categorical Part 50 or Part 52 licensee.

Appendix A, Item exclusion, it is unclear if this

1. 12, 10 CFR would apply to a 10 CFR Part 50 51.21 (or 52) license holder versus a Environmental Part 72 license holder versus a 32 Assessment (EA) fuel manufacturer/enricher. The vs. 51.22 second bullet for [burnup] BU and Categorical enrichment only discusses Exclusion performing an environmental (CATEX) assessment for transportation. It is unclear if an LAR (under 50.90) would require an EA based on Project Plan.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Reactivity, not enrichment, The language should be That language in the table reflects should be the figure of merit. revised to reflect the need to that which is in the Rule. No changes 50.68 even alludes to this. It says keep keff below 0.95, and let were made in response to this that [k-effective] keff must be less the licensee manage how to comment.

than 0.95; which makes sense. do that (enrichment, But it goes on to limit enrichment burnable poison, exposure, to 5%. With the potential need to spacing, rack inserts etc.).

increase enrichment levels for The facility specific both existing commercial LWR enrichment limit is included reactors and advanced reactors, in the facility license, so its the appropriate action is to inclusion in 50.68 is remove specific enrichment limits unnecessary.

from 10 CFR 50.68. Retention of the necessary enrichment limits in the facility licensing bases, including Technical Appendix A, Item 33 Specifications, provides

1. 15 adequate protection for criticality safety margins.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Under 235U Enrichment beyond Recommend changing will The NRC staff revised the note to Appendix A, Item 5.0 wt% it states Note: to may. NRC should check state, "Increased enrichment could

1. 17 on NUREG- Increased enrichment will for other prescriptive potentially lead to higher rod worth 34 0800 SRP promote higher rod worth and language in the document. and peaking factors."

Chapter 4.2 peaking factors and thus fuel enthalpy rise during RIAs.

Appendix A, #19 Studsvick is misspelled and Editorial correction. Typo corrected.

35 on NUREG- should be Studsvik 2121 Under Column 235U Enrichment Recommend revising this The NRC staff revised the text to beyond 5.0 wt% it states sentence (and other similar state, "Criticality code validation Criticality codes must be items for RG 1.240 and NEI needs to demonstrate that validation validated with experiments that 12-16, Revision 4 in the is applicable to the increased cover the applicable enrichment project plan) to be consistent enrichment range (discussion in range. As itemized in Section with the listed potential Section 8.1.4.1).

8.1.4.1 (page 33) of the Project approaches in Section Plan, there is more than one way 8.1.4.1 for this item. A Appendix A, Item to show that an experiment is recommended revision can

1. 23 on RG 1.240 applicable to a particular be: Criticality code 36 and NEI 12-16 validation. However, the way it is validation needs to Revision 4 written, this statement can be demonstrate that validation interpreted as validation has to is applicable to the be done using critical increased enrichment range experiments that cover the (discussion in Section applicable enrichment range and 8.1.4.1). Also - please therefore, new critical replace the word must with experiments are definitely may need to. Check the needed. document for the use of other prescriptive language.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Under Column Doped UO2 Fuel Recommend revising this The NRC staff revised the note to Appendix A, Pellets it states Note: sentence to be consistent state, "Criticality codes need to be Items #23 on RG Experiments for validation of with the listed potential validated for doped fuel." Per 1.240 and NEI criticality codes may be approaches in Section Section 7.1.4.1 of the ATF Project 12-16 Revision 4 necessary. Similar to previous 8.1.4.1 for this item. Plan, this could potentially be done in 37 and #24 on comments, the Project Plant numerous ways.

NUREG-0800 should list the alternative (Standard Review approaches (e.g., sensitivity and Plan 9.1.1) uncertainty analysis as discussed in Section 8.1.4.1)

Under Column Doped UO2 Fuel Recommend a note as in The NRC staff understands that for Pellets it states Note: RG 1.240 other places in green: existing dopants that have been Section C paragraph o states that Literature reviews and approved for use, research indicates for new fuel designs, justification research will provide that the dopants may have a minimal for continued use of the information on this technical impact on spent fuel pool criticality.

Appendix A, Item assumptions presented in NEI issue. However, if new dopants are

1. 23 on RG 1.240 38 12-16 Rev 4 may be necessary. developed, they may not exhibit the and NEI 12-16 This note treats doped pellets as same behavior. No changes were Revision 4 a new fuel design; existing work made in response to this comment.

from ORNL (and perhaps others) shows that for [spent fuel pool]

SFP criticality, dopants are of minimal importance.

Under Doped UO2 Fuel Pellets Clarify if the two fragments The NRC staff deleted this note it states Note: Higher density (separated by semi- colon) because it was not necessary.

fuel may lead to more 235U in are intended to be linked.

the spent fuel pool; experiments The first part of the note is for validation of criticality codes unnecessary and should be Appendix A, Item may be necessary. removed since criticality 39 #25 on NUREG-analyses must account for 0800 (SRP 9.1.2) fuel density accurately or conservatively. For the Second part - see earlier comment on Items #23 and

1. 24.

Comment Commenter Location in Plan Comment NRC Response Number Recommended Action Appendix B notes the possibility NRC should address the For topical report reviews, the ACRS of [Advisory Committee on steps that can be taken to review is an inherent part of the Reactor Safeguards] ACRS avoid ACRS reviews timeline. For LAR reviews, it is not reviews of industry submittals. delaying the approval of certain that ACRS review will be industry submittals, such as requested. NRC staff will follow early coordination with current guidance for requests by ACRS and conducting ACRS to review an LAR, which reviews in parallel. includes early engagement and coordination with ACRS staff. The 40 Appendix B additional time needed for an ACRS review is expected to be minimal and should not significantly affect the schedule for approving an LAR.

Figure B.1-1, blue box says SRP Change testing to The figures have been updated to 4.2 RIA testing. The use of the evaluation. reflect changes made to the table.

41 Appendix B term testing is too prescriptive.

Suggest changing it.

ML21314A531 OFFICE NRR/DORL/LPLII-2/PM NRR/DORL/LPLII-2/LA NRR/DORL/LP2-2/BC NAME MWentzel RButler DWrona DATE 11/12/2021 11/15/2021 11/16/2021 OFFICE NMSS/DFM/D NMSS/REFS/DD NRR/DRA/D NAME SHelton KCoyne MFranovich DATE 11/17/2021 11/17/2021 11/18/2021 OFFICE RES/DSA/D NRR/DORL/D NRR/DSS/D NAME KWebber BPham JDonoghue DATE 11/17/2021 11/18/2021 11/19/2021