ML18261A415

NRC Staff Response to Public Comments Received on the ATF Project Plan

ML18261A415
Person / Time
Issue date:	09/25/2018
From:	Mirela Gavrilas NRC/NRR/DSS
To:	Ho Nieh Office of Nuclear Reactor Regulation
Proffitt A
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ML18261A412	List: ML18261A414 ML18261A415
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Download: ML18261A415 (40)

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NRC STAFF RESPONSE TO COMMENTS RECEIVED ON THE NRCS ACCIDENT TOLERANT FUEL PROJECT PLAN DURING THE PUBLIC COMMENT PERIOD Proposed Comment Commenter Comment Resolution by NRC Staff Response Commenter Using a molten fuel injected into a reactor core heat exchanger designed to be molten as the maximum temperature possible for its purity and shape. When the cooling fluid flows to steam through the heat exchanger This comment does not directly the temperature would drop leaving a partly molten or pertain to the draft ATF project plan. It Donald solid mass in the reactor. With disruption if coolant fuel 1 has been provided to the advanced Desrosiers would become molten again for an easy purge from the reactor group in the Office of New reactor core stored in a container designed to change Reactors for consideration.

the shape and cross section if the fuel that it solidifies with a much lower storage temperature. Initial injection and reinjection after core purge will require fuel to be heated to specific molten injection temperature.

NRC staff recognizes DOE's 2 DOE Commitment to working together commitment to continued strong coordination with regard to ATF.

The terms outlined in the Memorandum of Understanding The Draft ATF Project Plan and associated (MOU) between the NRC and U.S.

Memorandum of Understanding (MOU) between the Department of Energy (DOE) were NRC and U.S. Department of Energy (DOE) are in examined to ensure they are not in conflict with NRC independence under the Energy conflict with NRC independence Reorganization Act of 1974. There have been a number under the Energy Reorganization Act of fully-closed meetings between DOE, reactor 3 Anonymous of 1974. NRC and DOE licensees, and the NRC, over a period of years, prior to independence in cooperative issuance of the MOU (Agencywide Documents Access programs are explicitly discussed in and Management System (ADAMS) Accession the implementing MOU No. ML17130A815). The public has had no opportunity (ML14072A366) in section V, to participate in or review the information subject to "Principles of Cooperation," part (b),

these closed meetings.

"General Guidelines for Cooperative Research Programs", which the 1

document referenced in the comment is an addendum to.

In addition, the staff has performed a review of all NRC sponsored meetings related to ATF and confirmed that they were conducted consistent with our internal agency processes outlined in Management Directive 3.5 Attendance at NRC Staff-Sponsored Meetings.

LTAs have been used safely for decades by the nuclear industry.

Contrary to Assumption No.1 in the Draft ATF Project However, the staff understands the Plan, the NRC has an obligation to perform independent need to clarify the treatment of LTAs confirmatory analysis prior to any new materials (fuel or in the design and licensing bases of 4 Anonymous cladding) being introduced as lead test assemblies reactors and a separate NRC steering (LTAs) and/or proposed for use in batch loading. committee has been established to Commercial operating reactors are not licensed as address the issue. The ATF project research and test reactors for DOE. plan will be updated to acknowledge this and to clarify the scope of the plan.

Existing agency processes, such as fuel design topical reports and license amendments for batch loading of ATF designs, are outside the scope of the project plan. A statement in the draft The applicability of licensing processes is poorly defined plan was intended to communicate in the Draft ATF Project Plan. The items in Task 1 and this and will be revised to enhance Task 3 neglect any discussion of amendments that may clarity. The purpose of the plan is to be required in accordance with 10 CFR 50.36 and 10 communicate how the agency will 5 Anonymous CFR 50.90. Contrary to licensing-avoidance strategy prepare for submission of ATF topical implicit in the Draft ATF Project Plan, any new materials reports and license amendments, in other than Zircaloy and ZIRLO cladding and UO2 fuel order to minimize delays and increase require prior NRC approval in accordance with the efficiency of the review. These regulations and licensee technical specifications. existing processes are already documented in many places. The project plan does not imply that license amendments and topical reports are not necessary for batch loading of ATF designs.

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Existing agency processes, such as fuel design topical reports and license amendments for batch loading of ATF designs, are outside the scope of the project plan. A statement in the draft plan was intended to communicate The Draft ATF Project Plan does not address this and will be revised to enhance plant-specific licensing issues including revising the clarity. The purpose of the plan is to accident analysis in Chapter 15 of the Updated Final communicate how the agency will Safety Analysis Report (UFSAR), changes to instrument prepare for submission of ATF topical setpoints, use of NRC approved codes and methods, reports and license amendments, in current licensed fuel limits less than or equal to 5%

6 Anonymous order to minimize delays and increase U-235 enrichment, issues related to changes in core efficiency of the review. These reactivity and approved methods in the core operating existing processes are already limits report (COLR). For enrichments greater than 5%

documented in many places. The U-235, the regulations in 10 CFR 50.68 may require regulatory framework for greater than additional controls and criticality instrumentation and 5% enrichment will need to be associated regulatory approvals.

examined if vendors indicate a desire to do so. Exemptions and/or rulemaking activities will need to be identified following the concept specific phenomena identification and ranking table exercises.

The regulatory evaluation in Task 1 of the Draft ATF Project Plan seems to presume all operating reactors ATF use in non-GDC plants will need are licensed based on 10 CFR 50, Appendix A, General to be assessed based on each plants Design Criteria [GDC]. Approximately 40% of the U.S. design criteria. As this is a operating reactors are licensed before the GDC and are plant-specific activity, going into detail 7 Anonymous commonly referred to as non-GDC plants. The Draft in the project plan would be ATF Project Plan does not state what emergency core premature. This will be clarified in the cooling system (ECCS) acceptance criteria will be used plan the first time the GDCs are by the NRC for non-GDC plants, if 10 CFR 50.46 is not mentioned.

useful as a means of satisfying GDC 35.

3

10 CFR 50.46 describes the acceptance criteria whereby plants using zircaloy or ZIRLO cladding and The regulations in 10 CFR 50.46 are explicit in stating UO2 fuel can meet the criteria in that use of materials other than zircaloy or ZIRLO GDC-35. If a licensee wishes to apply cladding and UO2 fuel , requires an exemption to be put this acceptance criteria to ATF they in reactors with zircaloy or ZIRLO cladding and UO2 8 Anonymous may need to request an exemption fuel. The Draft ATF Project plan should be more explicit and show that the criteria apply to the in providing guidance on the expectation for exemptions fuel in question. Otherwise, licensees for all material combinations other than zircaloy and may demonstrate compliance with ZIRLO cladding and UO2 fuel.

GDC-35 through an alternative means. No changes were made to the plan based on this comment.

Existing agency processes, such as fuel design topical reports and license amendments for batch loading of ATF Explicit discussion of topical report reviews is lacking in designs, are outside the scope of the the Draft ATF Project Plan. The Draft ATF Project Plan project plan. A statement in the draft should provide for explicit NRC review the results of plan was intended to communicate research in topical reports for each cladding and fuel this and will be revised to enhance variation. NRC should issue independent safety 9 Anonymous clarity. The purpose of the plan is to evaluations on those topical reports prior to approval of communicate how the agency will batch loading of ATF fuel. This is especially important if prepare for submission of ATF topical any research and/or associated topical reports are used reports and license amendments in as a basis to propose new coping times for order to minimize delays and increase time-to-core-damage.

efficiency of the review. These existing processes are already documented in many places.

The staff is aware that the industry may seek to recoup margin gained In Task 1, the Draft ATF Project Plan appears to be through the improved performance of biased toward crediting safety enhancements for fuel accident tolerant fuel in an attempt to that is not yet demonstrated. It is not apparent that ATF offset the economic costs associated 10 Anonymous fuel will perform as well as current operating reactor fuel. with the development and use of the It is, therefore, premature to assert changes in the fuel. At this time, the staff has not regulatory framework may be needed for crediting safety been approached with specific plans enhancements as described in Task 1. related to this type of initiative.

However, the staff will continue to fulfill its mission to provide reasonable 4

assurance of adequate protection of public health and safety.

The ATF working group (the working group) agrees with this comment.

When referencing 50.69, the plan is referring to the fact that changes in the PRA model owing to the plant The regulations in 10 CFR 50.69 provide for special response-related impacts of loading treatment of structures, systems, and components ATF may lead to changes in 11 Anonymous (SSCs). The regulations in 10 CFR 50.69 would exclude categorization (i.e., RISC 1,2,3, or 4)

ATF fuel from special treatment based on defense in for some components. The plan is depth as a primary fission product barrier. not suggesting that the fuel itself would be treated differently under 50.69. The phrase, "regarding Title 10 of the Code of Federal Regulations (10 CFR) 50.69" will be removed from pg. 2 of the plan to improve clarity.

The working group agrees with this comment. The plan is not suggesting a paradigm shift under which SPAR models would form the basis for LAR review. Instead, it is expected that the licensing review would follow current practices, where the NRC staff For Task 3, use of Standardized Plant Analysis Risk relies on risk information provided by (SPAR) models are insufficient as the sole basis for licensee models. Licensees are NRC approval of risk-informed licensing actions. The expected to continue the current MELCOR code is not normally used to supplement practice of developing and incomplete probabilistic risk assessment (PRA) analysis 12 Anonymous maintaining these models consistent for risk-informed licensing actions. NRC approved with NRC guidance (e.g., RG 1.200).

topical reports, incorporating results of research, is essential for consideration of any relaxations of coping The SPAR models are expected to be times and need to be supported by Chapter 15 UFSAR used predominantly at the oversight accident analysis.

phase, after ATF has been loaded. A parenthetical "(e.g., the Significance Determination Process)" will be added to the 2nd bullet on page 8 of the plan, after the word "activities," to make it more clear what this is envisioning.

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The Draft ATF Project Plan does not address the regulations in 10 CFR 20 that provide explicit dose 10 CFR Part 20 will be added to Task criteria for protecting workers and the public from 1 for review and consideration.

exposure to radioactive materials. While core damage The staff identified that ATF has the frequency (CDF) and large early release frequency potential to affect source term. Task 1 (LERF) are useful tools for risk-informed decision contains review of 50.67, "Accident 13 Anonymous making, they are not surrogates for requirements source term," RG 1.183, "Alternative concerning dose to workers and members of the public.

Radiological Source Terms for The Draft ATF Project Plan should have explicit Evaluating Design Basis Accidents at milestones for evaluating changes impacting dose to Nuclear Power Reactors," and workers and the public, including to changes to plant GDC 28, "Reactivity limits."

source term, release fractions, accident dose, control room habitability, and effluents.

The Draft ATF Project Plan lacks adequate discussion of NRC does not publish resource resources. In particular, there are timelines, but no estimates ahead of the formal budget resource estimates. Additionally, there is no discussion formulation process. The internal of funding and fee billing. The section entitled, 14 Anonymous document containing resource Preparatory Activities, states that a separate, estimates will be used to inform that non-public document also includes resource estimates process. No changes were made to each activity that will be used to develop budgets. A the plan as a result of this comment.

publicly available version should also be provided.

Although Assumption 3 and the discussion of Staff will consider the need for Stakeholder Interactions provides a general intent developing a formal communication according to NRC public meeting policy, a more explicit plan as our work related to ATF 15 Anonymous communications plan is needed for the general public evolves. Currently, the NRC staff and to address the interests of residents in local areas believe that the project plan is near the plants where ATF is proposed to be put in sufficient.

reactors.

6

The NRC agrees that timely development and submittal of quality licensing packages involving new materials followed by timely regulatory review will help ensure the materials are available consistent with utility needs. The primary coordination for UUSA recommends early coordination among the larger the development of timely and quality ATF community and the NRC to ensure timely licensing packages is the 16 UUSA development and licensing of packagings required for responsibility of the utilities and the higher assays or pellets/assemblies containing new fuel suppliers. The NRC will support materials on a time line consistent with utility needs.

requests for pre-application meetings to support industry's development of its licensing plans. NRC will provide estimates of the time required for specific licensing package reviews once it understands the content and the nature of the licensing request.

UUSA requests direct communication from the The NRC will place UUSA on its ATF 17 UUSA Commission on future proceedings communication list.

The NRC staff will support fuel cycle-wide industry ATF activities consistent with its resources and legal responsibility. The nature and timing of fuel cycle activities and the extent UUSA is interested in how the Commission will seek to of coordination between individual fuel support a fuel cycle-wide response to ATF activities.

cycle facilities is a matter for the 18 UUSA UUSA recommends a working group for such a project industry to determine. Industry to include at least one representative from each Fuel communication of its activities related Cycle Facility.

to fuel cycle licensing and the planned timing of these activities in a timely manner will allow the Commission to make the budget requests to support the industry ATF activities.

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The NRC staff would be willing to support such a fuel cycle facility working group in a manner that is consistent with its resources and role UUSA encourages a working group drawing from Fuel as a regulator. It would be Cycle Facilities, the Class 7 transportation community inappropriate for the Commission to 19 UUSA and utilities to identify appropriate packaging solutions, recommend specific packaging perhaps relying on a common set of criticality analyses solutions or criticality analysis to underpin any such evaluations.

methods. The staff would be willing to discuss any new criticality benchmark experiments or new packaging solutions the industry is considering.

UUSA is concerned because the proposed Draft Project Plan's supporting document, Task 2, Regulatory Framework Fuel Facilities, Transportation and Storage (ML173258774) states: "If enriched uranium greater that 5 percent U235 is needed, amendment requests are expected to authorize the plants to produce the higher The NRC staff recognizes that if enriched material. Any facility change to produce industry requests multiple complex U3Si2-based or uranium meta/based A TF is expected licensing actions in the same time to require an amendment which will likely require greater frame there is the potential for NRC effort than an amendment request for the production of resources to be over taxed. The NRC 20 UUSA U02-based A TF. It is expected that any such requests staff has and continues to request that would be made later. These activities are expected to industry provide the staff with be addressed in future updates of this plan as industry information on its plans including its plans become more certain." Although the quoted anticipated need for licensing actions.

language specifically refers to future activities with the The NRC staff uses such information overall project, UUSA is *concerned about multiple fuel to support its budget requests.

facility amendment requests being reviewed in unison. It is understood that such a project is a combined effort across the industry. Due to the limit of NRC resources, there is a potential for a significant impact to the review of operational LARs.

8

For these ATF designs, the time frames for initial LTAs have been used safely for irradiation of lead test assembly (LTA) programs and decades by the nuclear industry.

topical report (TR)/license amendment request (LAR) However, the staff understands the review were used as a basis for the timelines discussed need to clarify the treatment of LTAs in this plan. This statement clearly infers use of the in the design and licensing bases of Harold 21 topical report and amendment process. This is not reactors and a separate NRC steering Chernoff consistent with other public statements and documents committee has been established to prepared by NRC staff and that state that exemptions address the issue. The ATF project and amendments are not required for LTAs. What is the plan will be updated to acknowledge basis for statements that exemptions and amendments this and to clarify the scope of the would not be required for LTAs? plan.

The project plan does not cover existing licensing activities, as they follow existing processes for which LTAs have been used safely for schedules and regulatory approaches are decades by the nuclear industry.

well-established. This statement establishes that However, the staff understands the existing licensing and regulatory processes are well need to clarify the treatment of LTAs established. However, contrary to the well established in the design and licensing bases of Harold process, NRC staff in other public statements and 22 reactors and a separate NRC steering Chernoff documents prepared by NRC staff asserts that committee has been established to exemptions and amendments would not be needed for address the issue. The ATF project LTAs. This change from the well established process plan will be updated to acknowledge eliminates the publics opportunity to request a hearing this and to clarify the scope of the on an amendment request and to request adjudicatory plan.

intervention on an exemption on an activity that has irreversible consequences (i.e., irradiation of an LTA).

LTAs have been used safely for decades by the nuclear industry.

However, the staff understands the The activity section of Table 2 should also include a need to clarify the treatment of LTAs discussion and assessment of the licensing/regulatory in the design and licensing bases of Harold framework for use of LTAs. It is referred to in 23 reactors and a separate NRC steering Chernoff ML17325B773 which is referenced in the table. Any committee has been established to proposed changes to the well established process address the issue. The ATF project should be discussed and assessed in detail.

plan will be updated to acknowledge this and to clarify the scope of the plan.

9

Estimated lead times to develop the codes to be able to analyze all currently proposed fuel/cladding types range from three to six years. The lead time includes all code development activities, and considers the time required to generate new data and new models for code development and integral assessment. The lead times vary by discipline and vary for evolutionary and LTAs have been used safely for revolutionary ATF designs. Generally, longer lead times decades by the nuclear industry.

are estimated for revolutionary designs with the However, the staff understands the expectation that new phenomenological models will need to clarify the treatment of LTAs need to be developed and validated. The lead times are in the design and licensing bases of Harold 24 not independent between various ATF designs because reactors and a separate NRC steering Chernoff it is anticipated that code architecture updates made for committee has been established to the first design can be leveraged for other ATF designs. address the issue. The ATF project The existing regulatory requirements in plants technical plan will be updated to acknowledge specifications and core reload approved topical reports this and to clarify the scope of the stipulate that fuel, including LTAs, be analyzed with NRC plan.

approved codes and methods prior to irradiation. It is not clearly stated that NRC approved codes and methods must be used and that these approvals need to be in place prior to the irradiation of LTAs. This comment directly effects the content of Tables 6 through 9.

Although not necessary for inclusion in the plan, the assumption of appropriate resourcing to support The NRC staff continues to seek the it is essential in In the draft project plan of 9/6/2017, there was a fourth appropriate resources to fund and achieving timely assumption that NRC would be appropriately resourced support the activities outlined in the 25 NEI licensing of ATF to (staffed) to support the ATF research plan. This plan. Currently, we believe that we meet industry statement does not appear in the updated plan. will be appropriately resourced deployment moving forward.

objectives. There should be a mechanism in place for NRC to provide this assurance to all ATF stakeholders.

10

Suggest revising the text as follows:

Additionally, it is expected that all Additionally, it is expected that all integral fuel behavior reactor and test data will be provided to the NRC in a timely manner such generated fuel that integral assessment of NRC codes can be behavior data will be The staff will modify the plan to 26 NEI performed. What is meant by integral? Is this data provided to the NRC incorporate the proposed resolution.

different from the data referenced in the preceding in a timely manner sentence? such that assessment of NRC codes versus test data can be performed.

Eliminate any discussion of near-term designs (existing cladding The plan has bene updated to remove materials with new the "evolutionary vs revolutionary" The near-term ATF concepts that are contemplated have coatings) other than language. "Near-term" and been previously approved by the NRC in other forms the general "longer-term" ATF concepts are now (doped fuel and alternative zirconium based claddings) comments related to used to generally describe ATF using the current regulatory framework and existing NRC near-term designs in concepts where appropriate. We codes. The document implies that an extraordinary level the first 4 pages of have also clarified the staff's intent to of NRC effort (both from a review of regulations and from the document evaluate each ATF concept 27 NEI a code development perspective) is required to review because these individually while utilizing any prior these designs which is contradicted by past NRC concepts should not work to inform and enhance our approvals of similar designs. The document states on require a multi-year reviews. The plan has been updated page 1 The project plan does not cover existing implementation.

to reflect that level of effort should be licensing activities, as they follow existing processes for Only the new commensurate with the departure of which schedules and regulatory approaches are well physical, structural, the concept from previous designs established. or chemical aspects and that each ATF concept may have need to be assessed its own regulatory path.

to ensure no detrimental impact occurs from their addition.

11

The NRC staff believe Phenomena identification and ranking tables, or PIRTs, are a key step in defining the proper design parameters, SAFDLs and accident limits for each ATF.

Concept-specific PIRTs are one way to ensure that all new phenomena of safety importance have been identified and considered in planning test programs and code development activities. This includes both specific fuel and cladding changes and any credits that might be sought based on any margin gained.

The PIRT exercises need to be The project plan conducted consistent with the needs to consider concepts degree of departure from The plan should identify any NRC effort for changes how each ATF 28 NEI the state-of-practice. We recognize beyond the specific ATF fuel and/or cladding changes. concept ties into that some accident tolerant fuel safety benefits for concepts have limited new operating plants.

phenomena. Limited scope elicitation on knowledge gaps may be sufficient for small departures, while comprehensive review of a concepts potential impact on all GDCs may be needed for large departures Initial PIRT steps (to define issue, objectives and hardware/scenario) ensure the scope and depth of the exercise is well define before elicitation begins. The individual PIRTs will inform the regulatory path for that ATF concept. We plan to elaborate on the PIRT process and the individual regulatory paths in the final Project Plan to capture this.

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Clearly denote that specific materials When discussing doped UO2 pellets, coated cladding, or discussed are used more advanced pellet or cladding concepts, it should be as examples of the The staff agrees that clarification on clear that the specific material description is an example technology and do this point is helpful and the language 29 NEI of the concept. For example, the second paragraph of not define in the plan will be modified to clarify pg. 4 does not include doped UO2 pellets and its acceptable materials this.

exclusion does not provide the right level of complexity for pellet doping of the issue.

elements or cladding coatings, etc.

It is recommended that the NRC consider contemporary experience in The various coated Zr technologies may considered as a approving new The NRC staff have clarified our intent variation of normal fuel material development for materials that are to evaluate each ATF concept application to the current regulatory framework. variations of normal individually while utilizing any prior Additionally, ferritic stainless steels (i.e., FeCrAl) are (e.g., GNF-Ziron, work to inform and enhance our similar to conventional fuel in that metallic cladding and NSF, etc.) to reviews. The plan has been updated 30 NEI the cladding failure modes are expected to be similar. compare with the to reflect that level of effort should be As such, a regulatory framework for FeCrAl cladding is targeted review commensurate with the departure of expected to be similar to the existing framework and the cycles for coated Zr the concept from previous designs framework would be modified appropriately for the new ATF materials to and that each ATF concept may have claddings performance characteristics. evaluated how its own regulatory path.

current regulatory process capability can support the requested review cycles.

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For fuel concepts that are conventional cladding materials with an additional barrier (coatings) the licensing approach The ATF plan describes the agency's should use the preparation to conduct a timely and existing licensing efficient review of new concepts. It is The NRC project plan is not risk-informed. It starts off process to allow the not intended to describe policy with this caveat: The project plan does not cover new concepts to changes or new regulatory existing licensing activities, as they follow existing demonstrate their requirements. Instead, the plan aims 31 NEI processes for which schedules and regulatory performance. We to communicate the agency's actions approaches are well-established. The ATF project plan recommend that the that will allow for more streamlined is above and beyond the existing licensing actions for NRC assure the review and ensure that conventional fuels. degree of regulatory communication with vendors, interest & concern is licensees, DOE, and others takes consistent with the place to maximize the efficiencies.

amount of uncertainty and the potential consequence of performance uncertainty.

It is recommended The plan language will be modified to that each ATF address this comment by using the concept be terms "near-term" and "longer-term."

evaluated on an The terms evolutionary and In the second paragraph the last 2 sentences were implementation revolutionary were originally used as added to the description of evolutionary vs. timeline specific to terms of convenience to differentiate revolutionary ATF concepts. The first sentence simply that concepts among the technologies based on the explains the meaning of the terms (for the purposes of technical and current state of knowledge and level 32 NEI the research plan) and is a useful clarification. However, licensing attributes of departure from current designs.

the second sentence states that regulatory requirements considering whether The plan will be enhanced to make it do not vary between evolutionary and revolutionary that specific ATF clear that each concept will be treated (ATF) designs. It is not clear what this is intended to concept has any key on its own merits and the timeline and mean. policy discrepancies licensing roadmap will be dictated by and whether any the outcome of the phenomena regulatory identification and ranking table (PIRT) infrastructure would exercises.

need to be 14

developed to support that particular concepts implementation.

Similarly, the regulatory processes need to be evaluated for impacts to the metrics of CDF /

LERF based on different isotopic releases for each ATF concept. NEI suggests enhancing the project plan to differentiate between the types of concepts while not prescribing the exact lead times for implementation for multiple concepts rather than being binned with associated long development timelines based on non-specific lead time durations.

The industry has efforts underway to review potential An additional aspect to the licensing of ATF is a review regulatory changes NRC staff agrees with this statement.

of relevant regulatory infrastructure that may need to be based on expected This is covered by Task 1. No 33 NEI updated to enable realization of the safety and economic safety benefits and changes were made to the plan based benefits of ATF. will engage with the on this comment.

NRC steering committee later this year.

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The NRC should At this time, the NRC staff has had no consider reviewing indication from fuel vendors that they We suggest that the NRC consider reviewing preliminary intend to come in for licensing with an preliminary applications that are based on atomic scale applications that are atomistic scale modeling modeling and/or limited test reactor data with the based on atomic methodology. Instead, fuel vendors understanding that data that verifies the atomic scale 34 NEI scale modeling with have indicated that they plan to use modeling will come later. This will avoid a situation the recognition that these tools to inform the design of where a significant amount of data is transmitted to the data that verifies the engineering scale codes for licensing.

NRC at the conclusion of a test program while the NRC atomic scale If the vendors plan to pursue this is also reviewing the corresponding models.

modeling will come route, the NRC is open to starting a later. dialogue.

The ATF fuel placed in the spent fuel pool will be covered under the A review of operating plants license. In the plan, regulations for the review of requirements for ATF wet The document appears to address dry fuel storage complete life cycle storage is covered in Task 1 by Certificates of Compliance only and it omits wet storage should be review of 50.68, "Accident source of ATF in spent fuel pools. The project plan should 35 NEI considered for each term," GDC 61, "Fuel storage and include a review of regulatory requirements for storage ATF concept as handling and radioactivity control,"

of ATF in spent fuel pools and identify any changes regulations beyond GDC 62, "Prevention of criticality in necessary to allow storage of ATF in the spent fuel pool.

power operation may fuel storage and handling, " and be impacted. Chapter 9 of the standard review plan.

No changes were made to the plan in response to this comment.

Industry development schedules and As more information is known about regulatory licensing each ATF design and schedule the schedules need to ATF plan can be updated to better The project plan should provide a more innovative be aligned using capture the regulatory path of each risk-informed approach to licensing. Each ATF concept actual dates for each ATF concept. The plan has bene is unique and should be evaluated on its own merits concept yielding a 36 NEI updated to remove the "evolutionary rather than being binned into broad categories (i.e., critical path schedule vs revolutionary" language.

revolutionary and evolutionary) with limited development with considerations "Near-term" and "longer-term" ATF timelines based on non-specific lead time durations. for whether key concepts are now used to generally policy discrepancies describe ATF concepts where exist and where appropriate.

regulatory infrastructure may need to be 16

developed to support that particular concepts implementation.

This way the project plan can remain flexible and at a high enough level to be an effective guidance document providing individual timelines for each fuel concept based on that concepts specific features.

NRC needs to update existing prescriptive The project plan indicates that the NRC will: Identify regulatory processes whether, and if so what, regulatory guidance needs to be and guidance to generated to accommodate licensing ATF designs under improve regulatory the current regulatory framework. The current guidance stability and is based on Zr/UO2. predictability for future fuel reviews.

The lack of regulatory guidance for fuel systems that The industry has NRC welcomes further engagement differ from these prescriptive perspectives creates conducted initial on this topic and will consider regulatory unpredictability and instability as reviews and has updating relevant guidance based on 37 NEI demonstrated with the ATF LTA issue. The NRC ATF identified areas the concept-specific licensing plan does not address the need to update existing where we believe roadmaps developed for each regulations or regulatory guides to a higher level path changes to concept.

addressing key safety goals rather than the existing regulatory guidance prescriptive path for a specific fuel design. This are needed. We prescriptiveness of the fuel regulatory process severely stand ready to share limits innovation in fuel designs. Will NRC consider the results of our updating the current regulatory process as found in initial reviews and NUREG-0800 for more generic fuel reviews? provide input to the development of a prioritized schedule to move forward with 17

the necessary updates.

Continue and maintain the It is extremely positive that three different offices of the The NRC staff will continue coordination NRC are coordinating to produce and execute this plan. cross-office coordination during between NRR, The development and deployment of ATF technologies implementation and maintenance of 38 NEI NMSS and RES.

is very complex, so all regulatory aspects of the the ATF project plan through the Incorporate the products, and equally important, their benefits, have to steering committee and working responsibilities of be covered in the licensing roadmap. group.

each NRC office into the plan.

Near the beginning of the document, provide an overview of the document structure. Use labels and headings throughout the The readability of the plan should be enhanced. The document to enable organization of the document is confusing, and the the reader to document does not contain a roadmap of its contents. The staff believe that the structure of understand if he or The document appears to cover each major task twice. the plan is appropriate but will seek to 39 NEI she is in the The first 14 pages give an overview of the major tasks, increase the readability of the plan overview portion of including summary tables of each major task. Then each where appropriate.

the document or in major task is discussed a second time, but in more the detailed detail, in the remaining pages.

discussion portion of the document.

Consider integrating the two sections so that each task is addressed only once.

18

There is no need to delay until receipt of an applicants letter of intent. Issues can be discovered early in the development The concept of a "letter of intent" will timeline in parallel be clarified in the updated plan. The Please clarify the intention of the sentence The staff with any research or agency does not intend to delay expenditures to support design-specific regulatory development implementation of the plan and will 40 NEI hurdles will begin with the receipt of an applicants letter activities thereby seek to begin concept specific of intent (LOI) authorizing fee-based pre-application reducing the overall activities, including conducting PIRT activities. timeframe for exercises, immediately following the implementation. The issuance of the plan.

NRC should follow an off the fee based structure similar to advanced reactors for development activities.

The NRC should look for opportunities The GNF NSF experience where the NRC agreed to an to identify similar Best practices from the NSF program expanded Lead Use Channel program is viewed as a 41 NEI efficiency (and other LTA programs) will be best practice for accelerating experience while improvements and taken into consideration.

minimizing concerns over performance uncertainty.

the industry will also provide suggestions.

The plan notes a significant number of planned stakeholder interactions and The NRC should the staff believe that list to be identify a more sufficient, at this time. The plan is The document would be enhanced by providing efficient approach to 42 NEI intended to be a living document and opportunities for more direct input from stakeholders. continued the knowledge gained through the enhancement of the interactions outlined in the plan will plan.

help determine when updates are necessary.

Has NRC constructed a timeline that integrates Tasks Using currently 1-4 with the anticipated availability of data from DOE and available A milestone schedule has been added 43 NEI industry research efforts? Such a timeline would be information, to Section 3.1 of the plan to address beneficial in assessing the reasonableness and construct a timeline this comment.

scheduler risks of this plan. that integrates Tasks 19

1-4 with the anticipated availability of data from DOE and industry research efforts.

The plan is not clear on the expected involvement of the The plan has been updated to include NRC on the Phenomena Identification Ranking Table Further dialogue is a full section on the NRCs PIRT 44 NEI (PIRT) efforts, which are to be led by industry. The needed on this strategy on ATF. Section 3.4.3 industry is responsible for completion of the PIRT subject.

addresses this comment.

process.

The industry does The NRC is responsible for not see a value in independently verifying the safety Task 4 of the project case presented in topical reports and plan. The NRC license amendment requests. This could, instead of does not always require separate, developing codes to independent confirmatory calculations model the ATF using NRC developed tools. For designs, rely on the many incremental changes in fuel industry developed design, independent confirmatory codes. The NRC calculations using NRC developed could acquire the tools were not necessary. NRC codes and typically performs independent The document places a lot of emphasis on the supporting data from confirmatory analysis to review cases development of NRC codes to model all of the ATF 45 NEI the industry and where uncertainty is large or margin is designs. This effort is duplicative of the industry efforts perform a detailed small. For initial ATF licensing, where to develop codes to address the ATF designs.

review, including limited data will be available to sensitivity studies, as formulate and validate models, we part of their review of believe independent confirmatory the codes. This will calculations will be needed. In these result in both a cost instances, it is important that NRC and schedule staff performing confirmatory savings to both the calculations have clear understanding NRC and industry. of the assumptions and limitations of The document would the analytical tools they use. They need to be must understand the range of extensively modified conditions for which the code has to reflect the use of been validated and they must 20

industry versus NRC understand the nature of the codes. validation database. The NRC is open to discussing areas where industry codes, together with their validation database and documentation of code assumptions and limitations, could be provided to the NRC for use in independent verification of the safety case for ATF.

21

The staff believe Phenomena identification and ranking tables, or PIRTs, are a key step in defining the proper design parameters, SAFDLs and accident limits for each ATF.

Concept-specific PIRTs are one way to ensure that all new phenomena of safety importance have been identified and considered in planning test programs and code development The individual ATF activities. This includes both specific concept timelines fuel and cladding changes and any should be started credits that might be sought based on immediately to any margin gained.

support industry plans for deployment The PIRT exercises need to be of ATF. There is no conducted consistent with the need to delay until concepts degree of departure from receipt of an the state-of-practice. We recognize The mapping of the ATF specific hazards to regulations applicants letter of that some accident tolerant fuel 46 NEI could be done (or initiated) by the vendor advocating the intent. Issues can concepts have limited new fuel and cladding change.

be discovered early phenomena. Limited scope elicitation in the development on knowledge gaps may be sufficient timeline and for small departures, while discussions initiated comprehensive review of a concepts earlier to support an potential impact on all GDCs may be integrated schedule needed for large departures. Initial thereby reducing the PIRT steps (to define issue, overall timeframe for objectives and hardware/scenario) implementation. ensure the scope and depth of the exercise is well defined before elicitation begins. The individual PIRTs will inform the regulatory path for that ATF concept. We plan to elaborate on the PIRT process and the individual regulatory paths in the Project Plan to capture this. We have clarified the staff's intent to evaluate each ATF concept individually while utilizing any prior work to inform and 22

enhance our reviews. The plan has been updated to remove letter of intent.

23

The NRC staff disagrees with this comment. For effective use in their oversight role (SDP, ASP, MD 8.3),

the SPAR models must reflect the as-built, as-operated plant. To the extent that ATF significantly changes the PRA modeling and its outputs, the SPAR models should strive to reflect Consideration of these changes in order to provide ATF combined with accurate inputs into the oversight There are no tangible benefit to SPAR model upgrades other risk informed process. This is true regardless of 47 NEI (assuming that ATF provides the benefits perceived) applications should whether a particular plant seeks to until such time as applicants begin to try to credit 50.69. be considered as an implement risk-informed initiatives added activity (f) in such as 50.69.

Table 5.

If the change to PRA modeling/output for some ATF designs turns out to be modest, or if the agency decides to use a more qualitative approach to initial treatment of ATF in SDP, then it may make sense to defer model updates.

24

The NRC staff agrees in part with this comment. At this time, it is unclear whether ATF will be loaded in a phased versus complete-core-at-once manner. If the former, then the 50%

value may need to be re-visited. At present, it is simply intended as a marker for when overall core-wide response would start to be dictated by ATF performance. Some PRA aspects are driven primarily by core-wide response (e.g., total H2 production) while others are controlled by the most limiting assemblies (e.g.,

Footnote 1 defines a batch as 50% or more of the core. Revise the definition peak nodal temperature). In the This is too high. Batches are often approximately to be a more realistic future, the project plan may be 48 NEI 33-40% of the core. If this is a trigger, it will result in number. (e.g., updated to a value other than 50%,

program delays. ~30-40%) once more specifics are known.

In addition, the footnote in question will be expanded to include a statement similar to: "At present, this value is only intended to be illustrative of the binary nature of the PRA implementation approach. Some PRA aspects are driven primarily by core-wide response (e.g., total H2 production) while others are controlled by the most limiting assemblies (e.g.,

peak nodal temperature). Therefore, a different threshold or a graded approach may ultimately be needed."

In general, the PRA sections of the Project Plan are not as mature as EPRI could support other sections of the plan because the It is unclear who the MELCOR and MAAP meetings and these analyses with staff has not received definitive 49 NEI PRA meetings are with. review and comment information about the industry's by the vendors. interest in leveraging PRA methods in conjunction with ATF deployment.

The NRC staff welcomes 25

opportunities to discuss how EPRI could support the use of PRA methods for ATF.

The key schedule driver to provide the basis to fully capture The NRC staff believe Phenomena and realize ATF identification and ranking tables, or safety and economic PIRTs, are a key step in defining the benefits appears to proper design parameters, SAFDLs be the development and accident limits for each ATF.

of advanced Concept-specific PIRTs are one way modeling and to ensure that all new phenomena of simulation along with safety importance have been expedited identified and considered in planning experimental data test programs and code development collection. The new activities.

ATF concepts should be implemented The PIRT exercises need to be using the current conducted consistent with the The proper design parameters, SAFDLs and accident design process. For concepts degree of departure from limits for each ATF option need to be defined in order for example, the normal the state-of-practice. We recognize 50 NEI this activity to be performed. The vendors should define fuel engineering that some accident tolerant fuel the design and safety requirements and express what practice that includes concepts have limited new data is needed to support the requirements. full scale testing phenomena. Limited scope elicitation would be used to on knowledge gaps may be sufficient establish any update for small departures, while for the steady-state comprehensive review of a concepts hydraulic models potential impact on all GDCs may be and obtain DNB needed for large departures Initial data. The existing PIRT steps (to define issue, models and methods objectives and hardware/scenario) would then be ensure the scope and depth of the calibrated to the new exercise is well define before cladding material.

elicitation begins. We plan to Similarly, the elaborate on the PIRT process in the application of final Project Plan to capture emerging transient and plans.

accident codes would only be a variation of the 26

existing codes and methods driven by any new limits (e.g.,

establishing a new SAFDL that allows transient dryout for specified times as deriving from the materials and fuel performance work).

NRC is committed to conducting We look forward to efficient and effective reviews of ATF better understand designs consistent with our principles the justification for of good regulation. The timelines the anticipated Lead times identified in Table 2 have increased from the mentioned have been refined based increased lead times 51 NEI 9/6/2017 draft. These increases likely will impact on fine-tuning of NRC projections and support further industry timelines for ATF deployment. between issuance of the outline of the dialogue to identify plan and the draft plan. The plan is potential approaches meant to be a living document and will to reduce the continue to be kept up to date as we projected lead times.

move forward.

The staff recognizes that ATF licensing may require consideration of multiple aspects of fuel cycle licensing. The plan reflects the staff's current understanding of future industry requests for licensing actions.

The project plan should consider all aspects of licensing 52 NEI The staff continues to solicit including transportation and deployment requirements.

information updates from industry on its plans and needs for licensing reviews. Future revisions of the plan will reflect the licensing needs that industry has communicated to the staff.

27

Revise the discussion of transportation packages to include transportation of The staff recognizes the need to enriched uranium transport enriched uranium to fuel prior to its fabrication fabrication facilities. The staff The discussion of transportation packages does not into fuel assemblies.

recognizes the potential for industry to address transportation of enriched uranium prior to its Address request approval of packages for fabrication into fuel assemblies. Instead, the discussion transportation issues transporting material enriched greater is limited to transportation of fresh and used fuel with uranium in 53 NEI than 5 % or uranium in forms not assemblies. Also, the discussion does not address the various forms currently approved. Industry has not potential need for critical experiment benchmarks for enriched to greater notified NRC about plans to request enrichments greater than 5 wt% or for uranium in forms than 5 wt%. Address reviews of such packages. Future other than those now in use. the potential need for revisions of the plan will reflect the critical experiment licensing needs that industry has benchmarks for communicated to the staff.

enrichments greater than 5 wt% or for uranium in forms other than those now in use.

As stated in the project plan the schedule is very preliminary, but at present, PRA is not seen as an area that is likely to become critical path.

Publically-available information Describe how the provided by external stakeholders schedule articulated supports this view (see, for example, in this section NEI slides from Feb. 27, 2018 public How does the anticipated schedule articulated in this compares with 54 NEI meeting).

section compare with industrys anticipated schedule? industry intentions based on publicly The working group believes that the available PRA schedule should align information.

reasonably with the industry schedule (both of which are subject to change).

This item will be resolved by project-wide schedule development activities.

28

More clarity on what the commenter has in mind would be helpful. The staff does agree that the NRC should Please consider how study the impact that ATF may have ATF concepts may on existing regulatory programs and The plan does not account for potential synergies combine with other plant operations. This is the reason 55 NEI between ATF concepts and other regulatory programs. regulatory programs the working group believes it is critical to impact plant to have staff engaged throughout the operations. process. As this concept is already documented in the project plan, no changes were made as a result of this comment.

Modeling and NRC is required to independently simulation verify the applicants safety case.

capabilities While NRC is not required to have advancements that their own codes, verifying an exist today can applicants safety case sometimes shorten the licensing requires independent confirmatory timeline considerably analysis. For initial ATF licensing, and support a more where limited data will be available to transformational shift formulate and validate models, we in the NRCs believe independent confirmatory licensing approach calculations will be needed. The that is needed in codes NRC elects to employ for It is unclear what the NRCs basis for developing their order to license ATF independent confirmatory calculations own codes and methods. Will the industry need to wait and realize the will be determined based on the 56 NEI on the NRC to finish their independent methods safety and economic review schedule and the required development? benefits from these models for each ATF concept.

advanced The NRC maintains awareness and technologies while we are continuing to learn about the still maintaining the capabilities of the advancements in independent modeling and simulation. Validation confirmatory process of these tools against relevant data needed for a will be essential to demonstrate their thorough regulatory potential to support NRC's licensing review. This effort activities. While it appears that will require close advanced modeling and simulation collaboration and can play a useful role to inform alignment between experimental programs and identify the industry, DOE, testing priorities, we do not believe 29

the national todays advanced modeling and laboratories, and the simulation tools are mature enough to NRC which is substitute modeling for experiments.

essential for ATF to NRC's codes and methods have been be successful. specifically tailored to evaluate Advanced modeling regulatory requirements and and simulation (e.g., phenomena important to safety and RISMC, CASL, and they have been extensively validated.

NEAMS) can These features make them easy for facilitate ATF staff to use and give the staff high implementation with confidence in the results that they key support to provide. We have examined the utilities and vendors schedules provided by the fuel on design vendors and believe that the NRC's considerations, codes and methods can be updated normal operation on a schedule that supports our evaluations, and regulatory review activities.

ATF fuel performance assessments.

Therefore, the development of new NRC codes and methods may not strengthen the safety case and result in costly schedule delays.

The use of the tools now available to the NRC through their The NRC is currently coordinating collaborations with As part of NRCs review of vendor methods, the NRC with DOE and national laboratories to DOE and national can develop sufficient knowledge of phenomena to make better understand the capabilities of laboratories can 57 NEI judgments of adequate protection without spending the the DOE codes to potentially reduce reduce the time and time and resources to create yet another independent the number of time-consuming and cost of introducing set of methods based upon the same benchmark data. costly experiments and innovative demonstrations.

technologies into operating nuclear plants by reducing 30

the number of time-consuming and costly experiments and demonstrations.

The time and resource savings addresses one of the major hurdles in getting ATF to market NRC is required to independently The insistence on verify the applicants safety case.

NRC states that a major assumption is that they will doing this work While NRC is not required to have not perform independent confirmatory testing for specific independently will their own codes, verifying an ATF designs. It is expected that all necessary data seriously jeopardize applicants safety case sometimes needed to develop models will come from DOE, industry, the ability to achieve requires independent confirmatory or other organizations. Additionally, it is expected that the industry timelines analysis. For initial ATF licensing, all integral fuel behavior data will be provided to the NRC for ATF deployment. where limited data will be available to 58 NEI in a timely manner such that integral assessment of Also, the formulate and validate models, we NRC codes can be performed. NRC is not required to assumptions used to believe independent confirmatory have their own codes, only to maintain conflict of interest justify the need to calculations will be needed. The free confirmatory codes which could be done with DOE develop in-house codes NRC elects to employ for codes. The NRC codes are not designed to be easily codes are subject to independent confirmatory calculations updated and require substantial resources that will not challenge by will be determined based on the be developed in a timely manner.

industry. review schedule and the required models for each ATF concept.

The NRC should engage with industry and vendors regarding potential The project plan indicates that NRC will not perform test plans to ensure The NRC staff agrees. The MOUs independent confirmatory testing for specific ATF any confirmatory established with DOE and EPRI are 59 NEI designs, but, DOE and NRC have an MOU that DOE tests are designed to facilitate this has said that they perform tests that NRC requests. appropriately engagement.

focused and based on the attributes of the proposed ATF concepts.

31

The NRC project The NRC staff agrees that the plan plan is should be reassessed at a future date recommended to be In the attached detailed discussion of Task 4, NRC regarding regulatory initiatives such a living document.

indicates that the current plan does NOT consider new as changes to 50.69 or EP Industry has no 60 NEI regulatory initiatives such as changes to 50.69 or EP requirements. They were not recommendation at requirements. This limits the potential economic benefits considered in the plan because we this time and instead that may be obtained from ATF in the near term. had not received clear indication that suggests it be such initiatives would be pursed at the re-accessed at a time the plan was written.

future date.

It appears that the commenter is A parallel path for suggesting that there should be a data should exist path for fuel vendors to provide data Where possible, the NRC will collaborate with DOE in from the vendor to to the NRC for use in developing and each of these activities to reduce duplication of effort in the DOE and NRC.

61 NEI validating codes. There is nothing accordance with the DOE-NRC Memorandum of The DOE path is that precludes this. Each vendor Understanding1 information only for controls their own data and the NRC programmatic is willing to engage in dialogue on this considerations.

topic.

Suggest revising the text as follows:

Assessments of each of the updated codes, which The NRC staff agree with the includes verification comment and plan to revise the text and validation as follows: Assessments of each of Integral assessments of each of the updated codes, against data, will be the updated codes, which includes which includes verification and validation against data, completed and verification and validation against will be completed and documented. The duration of this documented. The 62 NEI data, will be completed and task is intrinsically linked to the production and duration of this task documented. The duration of this availability of data from on-going test programs, largely is intrinsically linked task is intrinsically linked to the focused on integral effects. to the production and production and availability of data availability of data from on-going test programs, largely from on-going test focused on integral effects.

programs, largely focused on reactor and test generated fuel behavior effects.

32

Further discussion is needed. We That statement was intended to recommend beyond identify the need to develop new, or design basis validate existing, accident source term It is unclear what is intended by and beyond DBA conditions be assumptions for ATF in order to 63 NEI conditions with respect to NRC licensing criteria? considered only if an satisfy requirements related to site ATF change resulted boundary dose, control room in a response habitability, and equipment change to a current qualification.

regulation.

The plan referred to scoping studies that will be performed by the NRC.

The scoping studies discussed in the The plan mentions scoping studies. It is not clear who is Clarify the context plan are to scope the code responsible for performing the scoping studies. Per the and responsibility for 64 NEI development and model update plan, it is understood that the NRC is not going to performing scoping needs presented by ATF. The conduct any tests. studies.

scoping studies referred to in the plan did not intend to refer to physical tests.

The project plan should differentiate between the types of concepts to provide a high-level roadmap for the The lead time quoted of three to six implementation of years included efforts to develop ATF concepts of that codes to be able to analyze near- and The last bullet on Page 10 states that the estimated lead type. It should long-term concepts. The project plan times to develop codes to be able to analyze all currently denote that this aimed to address ATF generally, but proposed fuel/cladding types range from three to six 65 NEI high-level timing is we recognize the need to develop years. This appears inconsistent with the Tables 6, 8, meant to be roadmaps for individual ATF concepts and 9, which show the lower end of the range to be 24 guidance and not a to better differentiate between types months for near-term concepts prescription of the of concepts. The NRC plans to begin exact time durations work on concept specific licensing for implementation roadmaps in the near future.

as each ATF concept would be evaluated on a timeline specific to that concepts 33

technical and licensing attributes.

Advanced Modeling and Simulation may be beneficial in helping to guide experiments but there are still many NRC should areas where the state-of-knowledge supplant fuel exam only permits semi-empirical modeling.

NRC need not always extensively benchmark/validate all data with advanced In these areas code validation is codes against experimental data. This is conventional modeling and critical. More discussion is needed to thinking, and will take a lot of additional time and effort.

66 NEI simulation (CASL, better understand the industry's vision Much international ATF R&D is in progress (China, Far NEAMS, etc.) using of integrating advanced modeling and East, Europe, Russia), and NRC should be willing to a wide variety of simulation in fuel licensing. The NRC utilize that data also (not just ATR, TREAT, and Halden).

reliable data points has, and will continue, to use data for benchmarking. produced outside of the country to assess codes as long as the data is deemed applicable to the fuel designs under review in the US.

34

By more closely aligning with DOE and national labs, the NRC can leverage the modeling and simulation (M&S) capabilities of their partners in lieu of developing their own redundant modeling and simulation capabilities based on the same data sets.

The near-term ATF For the near-term cladding technologies (i.e., coated Zr concepts would be The NRC maintains awareness of the

& FeCrAl), steady state neutronics analysis of the able to use existing advancements in modeling and reactor core is largely an effort for the fuel vendors to vendor and NRC simulation. There are areas of adequately introduce the nuclear properties (e.g.,

codes with minor cooperation between the DOE cross-sections) into the lattice physics methods to be modifications; CASL/NEAMs programs and NRC in 67 NEI applied. Validation will be performed via high fidelity however, the the area of neutronics. We expect to methods (e.g., MCNP). Standard processes for lattice longer-term ATF continue to follow DOEs development physics modeling of different materials are expected to concepts could efforts in this area, and look for be applicable. The need for an LTR to approve the benefit the most with opportunities to leverage their application of the lattice physics methods may depend a new advanced capabilities.

upon the methods applied and the specific material.

modeling paradigm that allows for accelerated implementation of innovative technologies. The NRC will need to develop confidence that these new advanced M&S tools can be used reliably in the regulatory process to evaluate fuel and system performance. We 35

encourage the NRC to work collaboratively with DOE, EPRI, vendors, and industry, to develop confidence to support accelerating licensing with CASL, NEAMS, and RISMC capabilities without the need for separate NRC code development.

68 PWROG Endorse NEI Comments N/A General 69 Endorse NEI Comments N/A Atomics In order to realize the benefits of ATF technologies within the remaining lifetimes of the existing nuclear fleet, the licensing timeline must be shortened as much As stated in the project plan, the NRC as possible. In particular, the development of will coordinate with DOE, consistent General independent computational models and tools imposes 70 with the terms of our MOU, where Atomics an unnecessary delay as presented in the project plan.

possible to reduce duplication of effort By more closely aligning with DOE and national labs, the and eliminate unnecessary delays.

NRC can leverage the modeling and simulation capabilities while maintaining an independent confirmatory process through regulatory review.

36

Each ATF concept will be evaluated based on its own merits. The plan has Each ATF concept is unique and should be evaluated on been updated to remove the General its own merits rather than being binned into two broad "evolutionary vs revolutionary" 71 Atomics categories, which may penalize technologies with the language. "Near-term" and greatest benefit. "longer-term" ATF concepts are now used to generally describe ATF concepts where appropriate.

The Draft Project Plan assigns any fuel with greater than 5 weight percent U235 to the longer of the two licensing paths outlined within. SNC recommends that the The identification of evolutionary and treatment of fuel with greater than 5 weight percent revolutionary fuels was developed to U235 enrichment be bifurcated. In addition, fuel with help bring clarity to the plan. The use enrichments up to 6 weight percent should be of 5 % enrichment as a break point considered in the shorter of the two licensing paths in was based in part on 10 CFR 50.68.

the Draft Project Plan. Rationale: Far fewer changes to As noted in the comment, it is the commercial fuel cycle are expected to be required to possible that some licensing actions 72 Southern accommodate up to 6 weight percent U235 than will involving material enriched to slightly likely be required for much higher enrichments. In some greater than 5 % could be portions of the fuel cycle, it may be possible to accomplished in a short timeframe.

accommodate up to 6 weight percent U235 with existing The plan will be revised to clarify that margin or with only minor changes. The use of not every licensing aspect of enrichments up to 6 weight percent U235 may have an longer-term ATF concepts will require economic benefit for ATF implementation, as well as a substantial time and effort.

collateral positive economic benefit for current fuel systems.

The staff recognizes the need to transport enriched uranium to fuel fabrication facilities. The staff The Draft Project Plan does not address transportation recognizes the potential for industry to of enriched uranium prior to its fabrication into fuel request approval of packages for assemblies. Please revise the Draft Project Plan to 73 Southern transporting material enriched greater clearly address transportation of enriched uranium with than 5 % or uranium in forms not greater than 5 weight percent U235 prior to its currently approved. Industry has not fabrication into fuel assemblies.

notified NRC about plants to request reviews of such packages. Future revisions of the plan will reflect the 37

licensing needs that industry has communicated to the staff.

Please include in the Draft Project Plan a schedule that integrates all 4 tasks. The schedule should identify assumed start dates, as well as identify the "critical path" to irradiation of reload quantities of ATF. The schedule should consider the availability of needed data from various industry research programs. Rationale: It is NRC has started developing an evident that the NRC staff has put considerable thought integrated timeline of activities from and effort into the development of the Draft Project Plan. Task 4, however, the exercise has However, without an integrated schedule, it is difficult to revealed there are still many aspects 74 Southern determine which subtasks need to be addressed soon, for which NRC staff must make which can be worked in parallel, and which can wait until significant assumptions. We welcome later. Without an integrated schedule, it is difficult to opportunities to obtain more details of understand when the NRC envisions being positioned to the schedule DOE and industry license an "evolutionary" or a "revolutionary" ATF research efforts.

product in reload quantities. It will also be difficult to track progress and assess the impact of breakthroughs or delays. A well-developed integrated schedule is essential to successful project implementation. [In line with NEI Comment 19]

38

The NRC staff disagrees with this On Page 8, Add the following shown below in red comment because the proposed (double underlined): Task 3: Probabilistic Risk Analysis markup would limit the relevant PRA Activities

• The staff will evaluate how industry batch model changes to success criteria, loading of A TF may affect the current risk informed whereas Task 3 explains that other programs like risk-informed technical specification changes are possible.

75 Southern (RITS) initiatives 4b and 5b

• The NRC's risk-informed oversight activities depend on standardized plan For example, ATF could impact other analysis risk (SPAR) models for which success criteria important PRA assumptions such as will need to be updated to reflect the HRA timing and core damage properties/characteristics of various ATF types and surrogate selection. Therefore, no batch loading of ATF changes were made as a result of this comment.

The NRC staff agrees in part with this comment. The proposed additions deal with activities related to MELCOR modeling and assessing the change in risk profiles and dominant contributors associated with ATF implementation. The former is the subject of other parts of the plan (Task 4), and is already addressed On Page 9, Table 5 PRA Activities, add the following there. The latter is a modest items under "Activity: (1) Incorporate elaboration on text already present, properties/characteristics of various ATF types into "to assess core damage frequency 76 Southern MELCOR to be used for PRA success criteria analyses.

(CDF)/large early release frequency (2) Compare risk profiles and dominant contributors to (LERF) impact, gain risk insights, and CDF/LERF from the PRA models before and after A TF identify potential improvements to

[In line with NEI Comments 7 and 8]

guidance." The working group agrees that the general area of risk insights includes the shift in significant risk contributors. In the subject table, under "Activity," in both columns for sub-item (c), language similar to

"(e.g., significant risk contributors to CDF/LERF)" will be added after "gain risk insights."

39

The NRC staff agrees in part with this comment; however, the commenter In Page 2 of the Task 3 section, the first appears to have misinterpreted the paragraph/sentence below the bulleted items states: term "internal" to mean "internal "The staff will need to ensure that licensee's PRAs events," whereas it is referring to the continue to use acceptable models and assumptions as NRC's internally-developed models part of the implementation of ATF and update internal (as opposed to licensee models cited 77 Southern models (as necessary) to reflect the ATF plant earlier in the sentence). The staff modifications. Rationale: In order to reflect the true risk agrees that PRA models of other of the plant, and any subsequent improvement from hazards (e.g., fire, seismic) should be ATF, all the other hazard PRA models (Fire, Seismic, updated along with the internal events etc.) should be updated along with the Internal Events PRA. In the subject quote, the word PRA model. "internal" will be replaced with "NRC's" to improve the project plans clarity.

40