ML21188A117

Project Plan to Prepare the U. S. Nuclear Regulatory Commission for Efficient and Effective Licensing of Accident Tolerant Fuels, Draft Version 1.2

ML21188A117
Person / Time
Issue date:	07/08/2021
From:	Office of Nuclear Reactor Regulation
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Wentzel, M NRR/LPLII-2
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Download: ML21188A117 (74)

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OFFICIAL USE ONLY - SENSITIVE INTERNAL INFORMATION PROJECT PLAN TO PREPARE THE U.S. NUCLEAR REGULATORY COMMISSION FOR EFFICIENT AND EFFECTIVE LICENSING OF ACCIDENT TOLERANT FUELS Version 1.2 T

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[Month] 2021 0

PROJECT PLAN TO PREPARE THE U.S. NUCLEAR REGULATORY COMMISSION FOR EFFICIENT AND EFFECTIVE LICENSING OF ACCIDENT TOLERANT FUELS 1 INTRODUCTION ................................................................................................................ 3 2 BACKGROUND .................................................................................................................. 4 2.1 NRC Staff Organization .................................................................................................. 6 2.2 ATF Workload Management and Staff Skillsets ............................................................. 6 3 ACCIDENT TOLERANT FUEL LICENSING PROCESS .................................................... 7 3.1 Assumptions ................................................................................................................... 8 3.2 Project Plan Paradigm.................................................................................................... 8 3.2.1 3.2.2 3.2.3 T

Old Paradigm................................................................................................... 9 New Paradigm ............................................................................................... 10 Phenomena Identification and Ranking Table Exercises .............................. 10 4

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R 3.2.4 3.2.5 AF Effectiveness of the New Paradigm............................................................... 12 Lessons Learned within the New Paradigm .................................................. 15 STAKEHOLDER INTERACTIONS ................................................................................... 16 INITIATING STAFF ACTIVITIES ...................................................................................... 18 5.1 Initiating Activities for FeCrAl and Longer Term ATF Technologies............................. 18 PREPARATORY ACTIVITIES .......................................................................................... 19 6.1 Task 1: Regulatory Framework, In-Reactor Performance ........................................... 19 6.2 Task 2: Fuel Cycle, Transportation, and Storage Regulatory Framework .................. 19 6.3 Task 3: Probabilistic Risk Assessment Activities ........................................................ 20 6.4 Task 4: Developing Independent Confirmatory Calculation Capabilities..................... 20 D

7 6.4.1 Advanced Modeling and Simulation .............................................................. 21 TASK 1: 10 CFR PART 50, 10 CFR PART 52, AND 10 CFR PART 100 REGULATORY FRAMEWORK, INREACTOR PERFORMANCE .............................................. 22 7.1 Regulatory Framework Applicability Assessment ........................................................ 23 7.2 Licensing Pathways ..................................................................................................... 24 7.3 Additional Considerations ............................................................................................ 25 7.4 Lead Test Assemblies .................................................................................................. 26 7.5 Initiating Activity ........................................................................................................... 27 7.6 Deliverables ................................................................................................................. 27 1

8 TASK 2: REGULATORY FRAMEWORK FUEL FACILITIES, TRANSPORTATION, AND STORAGE ........................................................................................................ 28 8.1 Facility, Transportation, and Storage Reviews ............................................................. 29 8.1.1 Uranium Enrichment and Fuel Fabrication Facility Reviews ......................... 29 8.1.2 Uranium Feed Material and Unirradiated Fuel Transportation Package Reviews ......................................................................................... 30 8.1.3 Irradiated Fuel Transportation Package and Storage Cask Reviews ............ 30 8.1.4 Potential Challenges...................................................................................... 31 8.1.5 Initiating Activity ............................................................................................. 34 8.1.6 Deliverables ................................................................................................... 35 9 TASK 3: PROBABILISTIC RISK-ASSESSMENT ACTIVITIES ....................................... 36 10 11 TASK 4: DEVELOPING INDEPENDENT CONFIRMATORY CALCULATION T

CAPABILITIES ................................................................................................. 41 COMPLETED PREPARATORY ACTIVITIES................................................................... 43 R

12 PATH FORWARD............................................................................................................. 44 APPENDIX A: REGULATORY FRAMEWORK APPLICABILITY ASSESSMENT .............. A-1 AF APPENDIX B: LICENSING PATHWAYS .............................................................................. B-1 APPENDIX C: CHANGE HISTORY ....................................................................................... C-1 D

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1 INTRODUCTION The U.S. Nuclear Regulatory Commission (NRC) is committed to enabling the safe use of new technologies, especially those that can increase the safety of NRC -regulated facilities. The U.S. nuclear industry, with the assistance of the U.S. Department of Energy (DOE), plans to deploy batch loads1 of certain accident tolerant fuel (ATF) concepts, fuels with higher burnup levels, and fuels with enrichment above the current 5 weight percent uranium-235 in the operating fleet on an aggressive timeline (by the mid-2020s). The NRC is optimistic that its preparation strategy and new paradigm of fuel licensing outlined in this Project Plan will support that schedule while still providing reasonable assurance of public health and safety at U.S. nuclear facilities and installations. The NRC understands that it may face challenges in its preparations and technical and licensing reviews, but it is committed to working through such challenges in a thoughtful and deliberative manner.

T In an attempt to increase regulatory stability and certainty, enhance and optimizing NRC review, and reduce the likelihood of not meeting the requested schedules (i.e., schedule risk), the staff R

has developed this plan, which includes a vision for a new paradigm for the licensing of ATF, higher burnup, and increased enrichment. The staff believes that adherence to this strategy will benefit all the agencys stakeholders in the planned deployment of ATF designs, higher burnup, AF and increased enrichment.

The NRC staff has extensively engaged with its stakeholders in the development and finalization of each version of the Project Plan, consistent with the NRCs principles of good regulation and statutory requirements. The staff has held one public meeting with external stakeholders, including licensees, nuclear fuel vendors, industry groups, nongovernmental organizations, and international counterparts for Version 1.2 and the meeting summary can be found in the Agencywide Document Access and Management System (ADAMS) at Accession Nos. MLxxxxxxxxx. The staff found this interaction and the previous interactions for ATF Project Plan Versions 1.0 and 1.1 (ADAMS Accession Nos. ML18261A414 and ML19301B166, respectively) invaluable, and has considered the views and comments of the NRCs D

stakeholders in finalizing this Version 1.2 of the ATF Project Plan.

The Project Plan presents the high-level strategy that the staff will follow to ensure that it is ready to review ATF, higher burnup, and increased enrichment topical reports (TRs) and/or licensing actions for the entire nuclear fuel cycle within the schedules requested by the industry.

At this point, the strategy is concept and technology independent. ATF concepts are defined as a family of ATF designs developed by vendors with largely similar characteristics. Examples include coated zirconium (Zr) alloy claddings, steel claddings, silicon carbide (SiC) claddings, or metallic fuels. Individual vendors may implement variations within each concept as specific technologies.

1 A batch reload is defined as the typical number of fuel assemblies that are replaced in the reactor core after each operating cycle; this is generally around one-third of the total fuel assemblies in the core.

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2 BACKGROUND In a coordinated effort under the direction of the NRCs ATF steering committee, the Office of Nuclear Reactor Regulation (NRR), Office of Nuclear Material Safety and Safeguards (NMSS),

and Office of Nuclear Regulatory Research (RES) are preparing for the licensing, fabrication or production and use of ATF, higher burnup, and increased enrichment in U.S. commercial power reactors.

In coordination with DOE, several fuel vendors have announced plans to develop and seek approval for various fuel designs with enhanced accident tolerance (i.e., fuels with longer coping times during loss of cooling conditions), higher burnup, and increased enrichment. The concepts considered in the development of this plan, both within and outside of the DOE program, include coated claddings, doped uranium dioxide (UO2) pellets, T

iron-chrome-aluminum-based (FeCrAl) cladding, SiC cladding, uranium nitride (UN) pellets (replaced the previously under-development uranium silicide (U3Si2) pellets), and metallic fuels (e.g., Lightbridge).

R Based on stakeholder interactions, the NRC staff is aware of industrys plans to request higher fuel burnup limits along with the deployment of near-term ATF concepts because it provides an economic balance to the increased cost of ATF. The staff expects an increase of fuel burnup AF limits up to approximately 75 gigawatt days per metric ton of uranium (GWd/MTU) rod-average (or equivalent). To achieve those burnups, the industry will need to requests increases in fuel enrichment from the current standard of 5 weight percent uranium-235 up to approximately 10 weight percent uranium-235, which the industry has labeled as low enriched uranium plus (LEU+)2. Additionally, on January 14, 2019, the President signed the Nuclear Energy Innovation and Modernization Act (NEIMA). NEIMA, Section 107, "Commission Report On Accident Tolerant Fuel," provides a definition of ATF as a new technology that: (1) makes an existing commercial nuclear reactor more resistant to a nuclear incident; and (2) lowers the cost of electricity over the licensed lifetime of an existing commercial nuclear reactor. Due to this economic link between higher burnup, increased enrichment, ATF technologies, and the NEIMA D

definition, pursuit of higher burnup and increased enrichment is considered a component of the ATF program.

This Project Plan covers the complete fuel cycle, including consideration for the front-end (i.e.,

enrichment, fuel fabrication, fresh fuel transportation) and back-end (i.e., spent fuel transportation and storage), and outlines the strategy for preparing the NRC to license ATF designs, higher burnup, and increased enrichment. It also identifies the lead organization for each planned activity. This plan only briefly touches on existing licensing activities, such as the 2

LEU+ is a term used by industry to describe the enrichment levels that the ATF near term concepts will be enriched to. Another term used by industry and DOE is the term high assay low enriched uranium (HALEU) which they define as fuel enriched from 5 weight percent uranium-235 and less than 20 weight percent uranium-235. Both of these industry terms fall under NRC regulatory definition of LEU defined in 10 CFR 50.2 as fuel in which the weight percent of U-235 in the uranium is less than 20%.

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TR process, the implementation of lead test assembly (LTA) programs, the license amendment request (LAR) process, and front-end and back-end licensing actions, as such activities follow existing processes that have well-established schedules and regulatory approaches or are being clarified through NRC initiatives outside of the ATF Steering Committee and Working Group.

In preparing the agency to conduct complete and timely reviews of these new fuel designs, the NRC is reviewing the existing regulatory infrastructure and identifying needs for additional analysis capabilities. The NRC has entered a memorandum of understanding (MOU) with DOE to coordinate on the nuclear safety research of ATFs that will make the appropriate data available for regulatory decision-making processes. In addition, the NRC has established an MOU with the Electric Power Research Institute (EPRI) to facilitate data sharing and coordination on expert elicitation.

T For the purpose of developing this plan, ATF concepts are broadly categorized as near-term and longer term. The plan considers near-term ATF concepts as those for which the agency can largely rely on existing data, models, and methods for its safety evaluations (SEs). Coated cladding, FeCrAl cladding, and doped UO2 pellets are the current near-term ATF concepts. The R

industry is pursuing coated cladding and doped pellets for deployment by the mid-2020s; however, licensing or deployment dates for FeCrAl have not been provided to the NRC at this time. Longer-term ATF concepts are those for which substantial new data, models, and AF methods need to be acquired or developed to support the agencys SEs. UN fuel, metallic fuel, and SiC-based cladding are the current longer-term ATF concepts. Near-term and longer term are often terms of convenience used to indicate the current expected deployment timeframe for the ATF concept. Potential licensing and deployment dates for the longer-term technologies have not been provided to the NRC at this time.

Regulatory requirements do not vary between near-term and longer-term concepts, and the NRC will evaluate all designs based on their individual technical basis. The timeline for licensing will be commensurate with the deviation of the ATF technology from the current state of practice and the number and complexity of issues related to phenomena identified during an D

expert elicitation process (e.g., a phenomena identification and ranking table (PIRT) exercise).

The agency is focusing its current ATF licensing preparation on the use of ATF in light-water reactors (LWRs) in the operating fleet. Some overlap may occur between LWR ATF fuel development and fuel safety qualification of some types of non-LWR fuels for advanced reactor designs. As appropriate, the NRC will leverage previous experience to help optimize licensing efficiency and effectiveness, and reduce schedule risk This Project Plan will be a living document that may evolve as (1) ATF concepts, higher burnup, and increased enrichment are more clearly defined, (2) schedules are refined, (3) the knowledge level of specific concepts increases as experimental testing programs are completed, and (4) potential extensions to the current operating envelope of fuel are identified.

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2.1 NRC Staff Organization The NRCs ATF, higher burnup, and increased enrichment activities are led by the ATF Steering Committee, which is made up of the executives who lead the technical and licensing divisions involved with ATF. The ATF Steering Committee is headed by the Director of the Division of Safety Systems in NRR.

Figure 2.1 The NRCs ATF Steering Committee ATF Steering Committee Office of Nuclear Reactor Office of Nuclear Office of Nuclear Material Regulation Regulatory Research Safety and Safeguards Division of Safety Systems Division of Systems Division of Fuel (chair)

Division of Operating Reactor Licensing Analysis T

Management Division of Rulemaking, Environmental, and Financial Support R

Additionally, the working-level ATF Working Group consistently contains staff members from:

AF Regulation Figure 2.2 The NRCs ATF Working Group ATF Working Group Office of Nuclear Reactor Division of Safety Systems Office of Nuclear Regulatory Research Division of Systems Office of Nuclear Material Safety and Safeguards Division of Fuel Division of Operating Analysis Management Reactor Licensing Division of Risk Division of Rulemaking, Division of Risk Assessment Environmental, and Assessment Financial Support D

Staff from many other Divisions and NRC Offices, have become involved in Steering Committee meetings and Working Group activities because ATF, higher burnup, and increased enrichment touches almost every aspect of the nuclear fuel cycle. The work necessary to prepare for ATF, higher burnup, and increased enrichment is truly an agencywide effort that requires coordination and support from multiple technical, projects, administrative, and legal organizations within the NRC.

2.2 ATF Workload Management and Staff Skillsets The majority of the staff efforts for ATF will be performed by the members of the divisions involved in the ATF Working Group; however, many different organizations can be involved with 6

ATF-related activities on limited bases. Staff from these other organizations, such as OGC and the NMSS rulemaking branch, may be requested to fulfill roles when needed. To ensure appropriate participation and effort, managers of the requested staff must approve of their ATF-related roles and assignments.

When it is determined that necessary skillsets are not available within the current staff, the NRC will put forth the effort to develop staff and contractors with critical skills required to support projected applications of high to moderate certainty.

3 ACCIDENT TOLERANT FUEL LICENSING PROCESS This Project Plan focuses on the NRCs preparations to conduct efficient and effective reviews for ATF designs, higher burnup, and increased enrichment on a schedule consistent with T

industry-requested timelines. Many different types of NRC reviews are necessary before ATF, higher burnup, and increased enrichment can be adopted by industry.

TRs provide the generic safety basis for a fuel design and do not, by themselves, grant approval R

for operating plants to begin loading ATF, higher burnup, or increased enrichment. These reviews for new fuel designs have historically taken between two and three years to complete.

Based on past experience, vendors should also anticipate that the NRCs Advisory Committee AF on Reactor Safeguards may request to review TRs and should include time for such reviews in their planning and schedules.

In addition, a licensee may need to submit a plant-specific LAR to modify its license to allow for the use of an ATF design, higher burnup, or increased enrichment. LARs address all plant-specific aspects of implementing an ATF design. Traditionally, new fuel design LARs are typically completed on a 18-month review schedule; however, the length of time required to review a new ATF design, higher burnup, and/or increased enrichment LAR is heavily dependent on many factors, including the amount of licensing credit requested by the licensee, number of components of the request (e.g., just an ATF design, an ATF design combined with D

higher burnup, or an ATF design combined with higher burnup and increased enrichment), and other relevant submittal information. Approximate LAR review timelines can only be provided to industry when applications are received and an acceptance review is performed to determine the scope of the review. Upon final approval of the plant-specific LAR, a licensee would be authorized to load and irradiate batch quantities of the specific ATF design, higher burnup, and increased enrichment in accordance with its license.

In addition to power reactor TRs and LARs, there are many necessary materials-related licensing actions for both the front-end and back-end of the fuel cycle both before and after batch loading of ATF, higher burnup, and increased enrichment into power reactors. Some examples of these actions are enrichment facility license amendments to increased allowed enrichment levels, fuel fabrication facility licensing to manufacture new fuel designs, changes to transportation package and dry cask certificates of compliance, and changes to specific licenses 7

for independent spent fuel storage installations. Many of the front-end licensing actions need to be completed in advance of insertion of fuel with ATF designs, higher burnup, and/or increased enrichment. The utilization of ATF, higher burnup, and/or increased enrichment would not be possible without these vital materials-related licensing actions.

3.1 Assumptions Given the current uncertainty related to the development and deployment of ATF concepts, the NRC staff made the following major assumptions to help in its development of this plan:

The NRC will not need to perform independent confirmatory testing for specific ATF designs, higher burnup, or increased enrichment. The NRC expects that the applicant, DOE, international multi-party research projects, or other organizations will provide the agency with all data needed to support the safety basis for a concept. Additionally, the T

NRC expects that all reactor and test-generated fuel behavior data will be provided to the agency in a timely manner so that it can assess NRC analysis capabilities. If NRC-performed confirmatory testing is necessary due to a large safety significance and uncertainty, then the timelines detailed in this Project Plan are no longer applicable.

R Interaction with DOE, EPRI, vendors, and other organizations involved in ATF-related experimental programs will take place in real-time and, whenever possible, in advance of experiments being conducted.

3.2 AF The NRCs interactions with external stakeholders will keep the staff and stakeholders informed about both technical and programmatic developments that are affecting activities identified in this Project Plan.

Project Plan Paradigm This Project Plan envisions an improved fuel licensing paradigm, depicted in Figure 3.1, that can increase the efficiency, increase the effectiveness, and reduce schedule risk of the NRCs review of ATF designs, higher burnup, and increased enrichment.

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T RAF 3.2.1 Old Paradigm Figure 3.1 ATF Project Plan new paradigm In the old paradigm, the NRC is reactionary to the nuclear industrys activities. The NRC would often find out about a new technology only when a vendor or licensee submits a licensing action or requests a presubmittal meeting close to the submittal date. At this time, the NRC staff would start three activities:

educating themselves on the technologies through research and discussion with the applicant.

assessing potential changes to the regulatory infrastructure once they have a sufficient D

amount of information from the submittal or presubmittal meeting.

developing the fuels analysis codes and models to ensure that independent confirmatory calculations are available for licensing needs.

This education, changes to regulatory infrastructure, and code and model development are started after the development of the technical bases for the new technology. Additionally, the lack of guidance and information exchange can result in a mismatch between submittals and NRC staff expectations, possibly resulting in resource intensive requests for additional information (RAIs) and extending the time necessary to resolve technical and/or regulatory issues. Both of these challenges can result in significant risk to the review schedule.

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3.2.2 New Paradigm Industrys pursuit of ATF, increased enrichment, and higher burnup has led the staff to reflect on the NRCs fuel licensing process and determine where improvements can be accomplished and where schedule risk can be reduced. The goal of this new paradigm is to enhance regulatory stability and reduce risk to the timeline required for licensing activities following the completion of the technical basis to support an ATF design, higher burnup, or increased enrichment.

As illustrated in Figure 3.1, the Project Plan encourages data and information sharing with NRC staff in parallel with the development of the technical basis for new technologies. The data sharing and early NRC staff engagement with the vendor during this time will be critical in reducing the schedule risk. In addition to the information sharing, the staff can begin familiarizing themselves with, and gathering information on, the technology at a much earlier stage. If appropriate, the NRC may also conduct a PIRT exercise for each ATF concept when T

necessary, as explained in Section 3.2.3 below. Based on the outcome of the PIRT process or other preparatory activities, staff may opt to make changes to the regulatory infrastructure as needed. Any changes to the regulatory infrastructure will involve significant communication with agency stakeholders to maintain transparency and clearly communicate regulatory expectations R

to the vendors. The staff also will begin preparing agency codes to minimize any lead time needed for performing confirmatory calculations after applications are received.

AF The success of the new paradigm is contingent on the early industry engagement and voluntary sharing of information with the NRC. Without these two key activities, the licensing process will have to proceed under the old paradigm, resulting in greater schedule risk.

3.2.3 Phenomena Identification and Ranking Table Exercises As stated above, the success of the strategy outlined in the Project Plan has the staff conduct thorough and meaningful PIRT exercises for each concept and maintain the results of the PIRT as the collective state of knowledge for each concept is advanced. For the purpose of this Project Plan, the term PIRT is defined as an expert elicitation process in which panelists will D

identify and rank new phenomena important to safety introduced by an ATF concept, higher burnup, or increased enrichment. The staff foresees that these exercises will vary greatly in scope and depth based on the departure of the concept from the current state of practice and the maturity of the concept. Some examples of potential exercises include independent NRC review of an industry generated failure mode analysis, a coordinated NRC and vendor exercise on a vendor-specific concept, and a multi-day PIRT panel with topical experts similar to previous NRC PIRTs such as on high-temperature gas reactors.

The experts selected for the PIRT panel should consider the full intended use of the concept to ensure that the PIRT results are meaningful even if initial licensing applications do not intend to seek credit for the enhanced capabilities of the concept. A lack of consideration of the full operating envelope in the initial PIRT exercise could lead to uncertainty further along in the process when a vendor or licensee does seek to credit those capabilities.

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The NRC staff relies on the agencys significant expertise in the Zr-clad UO2 fuel system during the review of current fuel licensing submittals. However, the staff does not necessarily have this same level of knowledge for all the ATF concepts, higher burnup, or increased enrichment that industry is currently pursuing. The NRC staff is monitoring the literature and experimental testing programs conducted in the public domain and is participating in industry and DOE update meetings on ATF concept development. However, more in-depth expertise may be needed to support the efficient and effective review of ATF, higher burnup, and increased enrichment licensing submittals. PIRT exercises will allow the staff to benefit from external expertise to identify phenomenon important to safety for each concept and, therefore, to refine the regulatory framework that is necessary for a concept ahead of licensing submittals and that will serve as baseline guidance for the NRCs technical review.

In addition to concept-specific PIRTs, discipline-specific PIRTs may be useful in some cases.

T Examples considered to date include PIRTs in the areas of severe accidents, storage and transportation, burnup above 62 GWd/MTU rod-average (or equivalent) and enrichment above 5 weight percent. The experts necessary to identify and evaluate new phenomena important to safety in these areas should be the same or similar experts for all or many of the ATF concepts, R

higher burnup, and increased enrichment under development. Therefore, the NRC staff believes that it would be more efficient to conduct these PIRTs in a discipline-specific manner instead of as part of the concept-specific exercises.

AF The NRC completed the first ATF PIRT exercise on Cr-coated cladding in June 2019. The PIRT began by collecting publicly available data on coated cladding concepts and producing an initial literature review, which was completed in January 2019 (ADAMS Accession No. ML19036A716). This literature review was used as background material for the experts who participated in the panel discussion and provided input to the final report (ADAMS Accession No. ML19172A154). This followed the schedule in the first version of the Project Plan.

Experts participating in the panel had background from academia, national labs, the nuclear industry and high temperature coatings. A multi-day public meeting was held where the experts D

discussed the initial report and their areas of expertise. After rating a list of fuel damage mechanisms by importance and level of knowledge the report was finalized.

This final PIRT report was then used to inform the development of interim staff guidance (ISG) on coated cladding. This guidance will be used to inform NRC staff reviews of coated cladding TRs and will ultimately be incorporated into NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition, otherwise known as the Standard Review Plan (SRP).

While the ISG was produced on an expedited timeline to facilitate issuance prior to the anticipated topical report submittals on coated cladding, the NRC staff have made efforts to include stakeholders in the process. This effort included opening the PIRT up as a public meeting, holding multiple public meetings on the ISG, and noticing the ISG in the Federal 11

Register for public comment. The ISG was issued on January 3, 2020 (ADAMS Accession No. ML19343A121).

The NRC completed a second PIRT exercise which covered the performance in severe reactor accidents of the current ATF concepts, higher burnup fuel, and fuel with enrichment above 5%.

It also assessed the impact of ATF, higher burnup, and increased enrichment on accident source terms. The PIRT exercise took place from September 2020 through April 2021 and was led by NRC contractors at Energy Research Inc. The final report was completed in April 2021 (ADAMS Accession No. ML21113A277).

The NRC will develop timelines for subsequent ATF PIRT exercises and additional implementation details through coordination with its external stakeholders.

3.2.4 Effectiveness of the New Paradigm T

The new paradigm for fuels licensing is a concept designed to increase efficiency and reduce schedule risk for NRC staff reviews of ATF, higher burnup, and increased enrichment licensing actions. It does not define the NRCs capability to review applications; the completion of the R

actions of the new paradigm (and the Project Plan as a whole) are not a go or no go measure determining if ATF technologies can be licensed today. The current licensing and regulatory framework continues to be applicable to near-term ATF, higher burnup, and AF increased enrichment without the activities promoted by the new paradigm. However, without these activities, there is increased schedule risk.

3.2.4.1 New Paradigm Effects on In-Reactor Topical Reports The determining factor on whether the TR reviews can be completed on the industrys requested expedited timelines is driven largely by the quality and completeness of the submittals, including the information and technical data received from all sources. ATF uses technologies that are being licensed for the first time; higher burnup and increased enrichment are not new technologies but go beyond previous limits. It takes time for the staff to become D

familiar with new technical issues and the challenges that these bring, and to incorporate the data into confirmatory codes. As seen in Figure 3.3, the more technical data and knowledge the staff has received before and with a submittal, the better prepared the NRC staff will be to perform an efficient review with less schedule risk. The early information and technical data necessary to achieve fewer RAIs and conditions on use will vary with each ATF concept, higher burnup, and increased enrichment. For example, coated cladding and doped pellets have a minimal departure from currently licensed fuel; therefore, a large portion of the information and data necessary to make a safety determination is available and understood by the technical staff. In contrast, information and data for higher burnup and increased enrichment is not as available; therefore, more is needed to make a safety finding.

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T Figure 3.3 Data and Information vs. New Paradigm Efficiency Additionally, communication with the applicants regarding their schedules is important to allow R

for the timely adjustment of staff resources for regulatory infrastructure changes (if any) and forthcoming submittals. Topical report project managers will encourage vendors to discuss their plans early and often regarding planned topical reports, including pre-submittal meetings.

AF Finally, the NRC needs to receive high quality3 submittals to meet the requested timelines. The increased communications and pre-application efforts will not be successful if applicants do not provide a complete and data-supported application.

As the NRC does not plan to collect its own technical data, there is an expectation that sufficient data to support the safety basis for an ATF concept will either be submitted with the licensing application or will be available in public literature or from other stakeholders.

3.2.4.2 New Paradigm Effects on In-Reactor License Amendment Requests D

Many of the aspects of the new paradigm translate into efficiencies for in-reactor LARs. Similar to the concept in Figure 3.3 for TRs, the more information the NRC has regarding a licensee's plans for in-reactor use, the more likely it will be that the NRC can meet the requested date for issuance of an amendment. Licensing project managers in the Division of Operating Reactor Licensing in NRR will encourage licensees to discuss their plans early and often regarding planned LARs, including pre-submittal meetings.

3 High quality consists of, among other things, quantities of data and detailed discussions sufficient to thoroughly support the assertions made in the submittal. Applications that do not adequately support the contained assertions often result in requests for information and extended review timelines because the staff is not initially able to make a safety determination without additional review steps.

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It is likely that licensees will be using varied approaches to license ATF, higher burnup, and increased enrichment for their facilities; therefore, the technical data needed by NRC staff to review ATF LARs is closely tied to the specific licensing approaches. For example, a licensing approach reliant on the performance of current fuel without taking additional credit for ATF safety improvements may require less data than one that takes significant credit for those improvements. For this reason, a defined set of required application contents could be unnecessarily prescriptive and inhibit flexibility by the applicant and the NRC.

The NRC staff is currently reviewing the regulations and guidance to identify the extent of their applicability to in-reactor LARs on coated cladding, doped pellets, higher burnup, and increased enrichment. A table of this applicability assessment can be found in Appendix A of this Project Plan and is discussed further in Section 7.1 of this plan. This list includes items that are not reviewed for most fuel-material TRs, such as dose assessments and environmental reviews.

The identification of a regulation or guidance that is not fully applicable does not mean that ATF, T

higher burnup, and increased enrichment LARs cannot be reviewed today; there are regulatory strategies that can be used to proceed forward in the review (e.g., sensitivity studies to ascertain the importance of parameters on predicting pertinent phenomena). However, schedule risk may be higher until such regulations or guidance are made fully applicable.

R 3.2.4.3 New Paradigm Effects on Front-end and Back-end Licensing Actions AF As with in-reactor LARs, many of the aspects of the new paradigm translate into efficiencies for fuel cycle front-end and back-end licensing actions. The more technical data and knowledge the staff has received before and on day one of a review, the more prepared the NRC will be and the lower the risk that the review will not meet the requested expedited timeline due to unforeseen technical or regulatory issues. The NMSS project managers will encourage their licensees and certificate holders to discuss their plans early and often, including pre-submittal meetings.

The NRC staff is currently reviewing the regulations and guidance to identify the extent of their applicability to front-end and back-end licensing actions on coated cladding, doped pellets, D

FeCrAl cladding, higher burnup, and increased enrichment can be found in Appendix A of this Project Plan and is discussed further in Section 7.1 of this plan. The identification of a regulation or guidance that is not fully applicable does not mean that ATF, higher burnup, and increased enrichment front-end and back-end licensing actions cannot be reviewed today; however, schedule risk will be higher until such regulations or guidance are made fully applicable.

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3.2.5 Lessons Learned within the New Paradigm Below are some broad lessons learned from experiences in the new paradigm with LTAs, TRs, and other licensing actions that will help the NRC ensure efficient reviews of ATF technologies.

Commitment to any specific technology from power reactor licensees is important for resource planning. The fuel vendors are strongly pushing ahead and are interacting with NRC staff. The NRC staff is looking forward to receiving scheduling information from power reactor licensees so the staff are able to prepare for license amendments to the desired extent.

Early communication and pre-application interactions between the staff and applicant/licensee is essential for all licensing actions across the entire fuel cycle Staff knowledge is needed on how the technology meets (or fails to meet) the consensus codes and standards and/or regulations prior to submittal T

Staff knowledge of past research and staff ability to conduct appropriate confirmatory research to strengthen the basis for reasonable assurance of adequate safety are needed If the data is still being collected, the applicant will need to compensate for the lack of R

data to provide a safety basis.

Significant coordination across the NRC Offices is paramount and many technical disciplines are included across the agency.

AF D

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4 STAKEHOLDER INTERACTIONS The new paradigm for ATF, higher burnup, and increased enrichment employs early communication with stakeholders to maintain transparency and provide regulatory stability through the issuance of documents, such as the coated cladding ISG, and outreach activities, such as discussions during public meetings, conferences, and NRC-led workshops. The NRC is committed to actively engage in industry project update meetings and support staff participation in experimental program discussions to maintain awareness of industry and DOE efforts to prepare for regulatory reviews. The staff will continue to follow existing NRC policies for all stakeholder interactions regarding ATF, higher burnup, and increased enrichment.

The NRCs enhanced stakeholder communications are designed to:

Allow NRC staff to become more familiar with ATF concepts, which will help enable T

more efficient review of ATF applications.

Remain closely engaged with the organizations and entities acquiring data and adjust this Project Plan as new information becomes available.

Prevent delayed recognition of required changes to the regulations or guidance to R

reduce schedule risk. The staff has initiated dialogue with stakeholders to communicate timelines required for modifications to the regulatory infrastructure and to solicit input for AF changes that may be necessary for the different ATF concepts.

Allow a more efficient NRC resource reallocation due to industry changes in direction and schedules.

Provide opportunities for the public to interact with the NRC and provide input since the industrys ATF, higher burnup, and increased enrichment deployment is expected to request an accelerated licensing schedule.

Table 4.1 outlines key meetings and interactions scheduled during the development and review of ATF designs.

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Table 4.1 Meetings and Stakeholder Interactions Meeting Frequency Desired Outcome Assess the technical progress of ATF EPRI/DOE/Idaho National research and development (R&D).

Laboratory (INL) update Biannually Obtain information necessary for developing meetings analytical capabilities and licensing strategies.

TOPFUEL (rotates between Assess the technical progress of ATF R&D.

the United States, Europe, Annually Obtain information necessary for developing and Asia) analytical capabilities and licensing strategies.

ATF standards and guidance development activities with the Organization for Economic Co-operation and Discuss licensing approach with international Annually Development /Nuclear counterparts.

Energy Agency, International Atomic Energy Agency, and international counterparts T Assess the technical progress of ATF R&D.

R Fuel vendor update meetings Obtain information necessary for developing (rotates from NRC Annually analytical capabilities and licensing strategies Headquarters to the vendors (per vendor)

(in addition to a number of other non-ATF AF headquarters) outcomes).

ATR/TREAT test planning Develop an understanding of testing that will As and test observation characterize the performance characteristics scheduled meetings of ATF designs.

International Conferences As Understand and coordinate ATF research and and Workshops scheduled knowledge with international counterparts Develop an understanding of manufacturing ATF fuel fabrication facilities As needed processes and obtain information for tour and audit developing licensing strategies.

Participation CRAFT and As Assess the progress of industry and provide D

ESCP committees DOE/NRC management meetings Design-specific pre- and post-submittal meetings NRC-initiated focused-topic meetings scheduled Monthly As needed As needed NRC viewpoint when requested.

Discuss progress and coordinate ATF activities.

Discuss technical subjects with vendors and licensees. These meetings will contain a public portion when possible for public comment.

Provide information and the ability for the public to interact with the NRC on a specific technical and regulatory area(s) 17

5 INITIATING STAFF ACTIVITIES Because of design-specific aspects and schedules, the NRCs activities are linked to the industrys progress and plans to deploy ATF, higher burnup, and increased enrichment. For this reason, the agency must have ways for communicating schedules and resource needs in advance of licensing activities. One way to communicate schedules with industry is through routine project manager interactions with vendors and licensees. Power reactor, vendor, and fuel cycle project managers will communicate with their vendors and licensees as needed to maintain awareness of changes to schedules and/or direction. Additionally, fuel vendors host routine update meetings, such as the annual fuel update meetings listed above. As with the informal communication with project managers, these meetings provide awareness of any changes to vendor schedules and/or direction.

The staff will choose to issue generic communications when deemed necessary to obtain T

industry schedules. To understand fuel cycle vendor and licensee progress and plans, the staff issued Regulatory Issue Summary (RIS) 2019-03, Pre-Application Communication and Scheduling For Accident Tolerant Fuel Submittals, on November 20, 2019 (ADAMS Accession No. ML19316B342). This RIS seeks ATF scheduling information for preapplication activities, R

topical report submittals, and other licensing submittals from 10 CFR Part 70, 71, and 72 licensees. Generic communications to power reactor licensees will be issued on an as-needed basis.

AF This Project Plan provides estimated lead times for each agency activity associated with preparing to conduct effective and efficient licensing reviews of ATF TRs, LARs, and front-end and back-end licensing actions. As the NRC staff gains more experience with these reviews, it will adjust lead times to account for difficulties or efficiencies, as necessary. These lead times dictate when data should be provided by the vendors or licensees ahead of submittals and a formal communication of intent should be made through a response to a RIS, pre-submittal meetings, or other formal interaction with the staff as discussed above.

5.1 Initiating Activities for FeCrAl and Longer Term ATF Technologies D

The staff is aware that in the current environment, the focus, momentum, and majority of capital investments for the industry is on coated cladding, doped pellets, higher burnup, and increased enrichment. The NRC staff will start the refinement of the regulatory infrastructure for the other technologies (i.e, FeCrAl cladding, SiC cladding, UN pellets, an extruded metallic fuel) when the industry members provide projected submittal dates for future licensing actions for those technologies. The staff shall maintain discussions with the vendors and possible applicants to learn when future licensing actions will be submitted.

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6 PREPARATORY ACTIVITIES The NRC staff has grouped its preparatory activities into four tasks. The highlights of each task are briefly described below; subsequent sections describe these tasks in full detail.

6.1 Task 1: Regulatory Framework, In-Reactor Performance Participate in coordinated PIRT exercises on in-reactor degradation mechanisms and failure modes under a wide array of accident conditions, performance-based metrics, and analytical criteria to ensure acceptable performance.

Perform a review to (1) evaluate the applicability of existing regulations and guidance for each ATF design, higher burnup, and increased enrichment (2) identify changes to, or the need for, new regulations and guidance, and (3) identify any key policy issues. The

T table in Appendix A of this Project Plan provide this information for coated cladding, doped pellets, higher burnup, and increased enrichment, which industry plans on adopting in the near term (mid-2020s). The staff are developing plans to resolve the actions contained within the table.

R Identify consensus standards that need to be updated for ATF, higher burnup, and increased enrichment and participate in the update process where appropriate.

Determine and clarify the regulatory criteria that need to be satisfied for partial or full AF core use of ATF, higher burnup, and increased enrichment and the regulatory options available to applicants and vendors. The ISG for chromium coated cladding was released to satisfy this task, and the staff are continually assessing the need for additional work on this task for higher burnup and increased enrichment.

As needed, resolve policy issues and initiate rulemaking and guidance development activities. Because of industrys intent to adopt increased enrichment, the staff has begun the process of requesting approval from the Commission to investigate further.

Prepare for the submission of LARs by industry that may contain many differing ATF, higher burnup, and increased enrichment adoption strategies. To support planning efforts, the NRC staff provides consistent requests to licensees for information regarding their adoption plans.

D 6.2

Task 2: Fuel Cycle, Transportation, and Storage Regulatory Framework Perform a review to (1) evaluate the applicability of existing regulations and guidance for each ATF design, higher burnup, and increased enrichment, (2) identify changes to, or the need for, new regulations and/or guidance, and (3) identify any key policy issues in the areas of fuel cycle, transportation and dry cask storage.

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Applicable regulations are 10 CFR Part 70, Domestic Licensing of Special Nuclear Materials; 10 CFR Part 71, Packaging and Transportation of Radioactive Material; and 10 CFR Part 72, Licensing Requirements for the independent Storage of Spent Nuclear Fuel and High-Level Radioactive Waste, and Reactor-Related Greater Than Class C Waste, which are largely performance based; therefore, the staff does not anticipate identification of gaps or deficiencies in these regulations for licensing or certification of ATF designs, higher burnup, and increased enrichment.

In preparing staff to receive applications related to ATF concepts and increased enrichments, NRC developed a critical path schedule that was sent to stakeholders on August 26, 2019 (ADAMS Accession No. ML19235A261), identifying key dates for which NRC should receive licensing and certification applications from fuel facilities and fuel vendors to conduct an efficient review in order to support industrys ability to achieve ATF deployment in 2023.

Applicability of the current guidance may change as the fuel cycle industry develops T

plans for manufacturing, transporting, and storing ATF, higher burnup, and increased enrichment. The NRC will monitor the fuel cycle industrys plans and develop any necessary new or updated regulatory guidance in a timely manner.

6.3

R Task 3: Probabilistic Risk Assessment Activities The staff will evaluate how industry batch loading of ATF, higher burnup, and increased AF enrichment may affect the current risk-informed programs such as risk-informed technical specification initiatives 4b and 5b (ADAMS Accession Nos. ML18183A493 and ML090850642, respectively).

The NRCs risk-informed oversight activities (e.g., the significance determination process) depend on standardized plant analysis risk (SPAR) models, which may need to be updated to reflect the batch loading of ATF, higher burnup, and increased enrichment. The staff is using the independent confirmatory calculation capabilities, as discussed below in Task 4, to evaluate the new technical information as it is received.

The results from these calculations along with requested license amendments will be used to support any needed SPAR model updates.

D 6.4 Task 4: Developing Independent Confirmatory Calculation Capabilities The NRC typically performs independent confirmatory calculations to review cases in which uncertainties are large or the margin is small regarding the safety of the proposed change.

These calculations performed by the staff provide increased confidence in the applicants results. For initial ATF, higher burnup, and increased enrichment licensing for which limited data will be available to formulate and validate models, independent confirmatory calculations will likely be needed. In these instances, the staff that performs the confirmatory calculations must have a clear understanding of (1) the assumptions and limitations of the analytical tools that it uses, (2) the range of conditions for which the code has been validated, and (3) the nature of the validation database.

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Based on the information available to date, the staff believes it will be more efficient and effective to pursue relatively minor modifications to existing NRC codes to model near-term ATF fuel concepts, higher burnup, and increased enrichment. The NRC has specifically tailored and extensively validated its codes to evaluate regulatory requirements and phenomena important to safety. These features make the codes easy to use and provide the staff high confidence in the results. At this time, the NRC plans to modify the codes that are developed to analyze fuel performance, thermal hydraulics, neutronics, and severe accidents and source terms. In addition, the staff is considering modifying existing NRC-developed codes to model longer term ATF fuel concepts in cases that require minimal effort. A more detailed discussion of this effort, including the status of NRC staff activities, can be found in Section 10.

Where possible, the NRC will coordinate with DOE to reduce duplication of effort.

6.4.1 Advanced Modeling and Simulation T

NRC staff maintain an awareness of the advancements in modeling and simulation for nuclear applications. The staff expects to continue to follow DOEs development efforts in the area of advanced modeling and simulation and to search for opportunities to leverage their capabilities.

The staff is aware of efforts to use advanced modeling and simulation in a variety of applications R

or families of codes: mechanistic codes, steady-state codes, and transient codes. Although advanced modeling and simulation in mechanistic codes can inform experimental programs, improve upon highly empirical correlations, and identify testing priorities, current advanced AF modeling and simulation tools do not appear to be mature enough to substitute modeling for experiments because of the complex nature of fuel and reactor behavior. Further, the state of knowledge in many areas still only permits semi-empirical modeling of key phenomena.

Validation of these tools against relevant data will be essential to demonstrate their potential to support licensing activities. The staff will continue to coordinate with DOE and the national laboratories to better understand the capabilities of the DOE codes to potentially reduce the number of time-consuming and costly experiments and demonstrations.

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7 TASK 1: 10 CFR PART 50, 10 CFR PART 52, AND 10 CFR PART 100 REGULATORY FRAMEWORK, INREACTOR PERFORMANCE To prepare the agency to conduct complete and timely licensing reviews of ATF designs, higher burnup, and increased enrichment, well-developed and vetted positions are needed on potential policy issues that may arise during the review and licensing process. These positions must be communicated to stakeholders clearly and early.

This task contemplates two distinct ATF concept activities that may require changes to the regulatory framework to be performed within the requested timeframes: (1) approval of TRs and LARs to allow batch loading of ATF into NRC-regulated power plants and (2) crediting the safety enhancements of ATF in the licensing basis of NRC-regulated power plants. The regulatory T

framework changes that may be necessary for each of these activities are likely to be different, and the staff anticipates that such changes will need to be made to address batch loading before making changes needed to credit the safety enhancements of ATF in the licensing basis.

R This task also addresses the changes to the in-reactor regulatory framework that may be required to support the implementation of higher fuel burnup and increased enrichment considering the technical issues they present. Generally, the technical issues associated with AF higher fuel burnup and increased enrichment respectively fall into two categories: (1) fuel integrity (cladding or fuel pellet) and (2) nuclear criticality safety. Emergency Core Cooling System (ECCS) performance embrittlement mechanisms and fuel fragmentation, relocation, and dispersal are examples of fuel integrity technical issues associated with higher burnup. Spent fuel pool criticality and potential fast critical conditions during accident scenarios are examples of the technical issues associated with increased enrichment that fall under nuclear criticality safety. The need to make changes to the regulatory framework to address each technical issue is likely to be different. For example, although licensees will be able to seek approval for the use of fuel with increased enrichment through the exemption process, the staff is investigating revising the regulations so that increased enrichment can be predictably licensed for use D

outside of the exemption process.

The degree to which existing regulations and guidance are affected and in need of revision, or new regulatory requirements established and new guidance developed, depends on the level of departure from existing fuel designs and burnup and enrichment limits. The regulations at Appendix A, General Design Criteria for Nuclear Power Plants, to 10 CFR Part 50, Domestic Licensing of Production and Utilization Facilities, provide principal design and performance requirements. The general design criteria (GDC) listed in Table 7.1 relate to fuel design and overall fuel performance under normal and accident conditions. Regarding ATF, these and additional GDC may be affected if ATF performance becomes more challenging for the control or protection systems that ensure acceptable consequences under accident conditions. For each ATF design, the staff plans to map the hazards and failure mechanisms to the design and performance criteria of the GDC to determine the appropriate applicability and potential need for 22

additional criteria. Regarding higher burnup and increased enrichment, the NRC staff has concluded the GDC discussed within Appendix A to 10 CFR Part 50 will not be affected. While higher burnup and increased enrichment may impact the way compliance with regulatory requirements is demonstrated, the actual principal design and performance requirements provided by the GDC remain applicable.

Note that loading an ATF or increased enrichment fuel design in a specific plant will ultimately need to meet relevant plant-specific criteria. This is especially important for those reactors in the United States that were licensed before the issuance of the GDC (about 40 percent of the operating plants).

Table 7.1 Potentially Affected GDC GDC No. Title 1 Quality Standards and Records 2

10 11 12 Reactor Design Reactor Inherent Protection T Design Bases for Protection against Natural Phenomena Suppression of Reactor Power Oscillations R13 20 25 AF 26 27 28 34 35 61 Instrumentation and Control Protection System Functions Protection System Requirements for Reactivity Control Malfunctions Reactivity Control System Redundancy and Capability Combined Reactivity Control Systems Capability Reactivity Limits Residual Heat Removal Emergency Core Cooling Fuel Storage and Handling and Radioactivity Control 62 Prevention of Criticality in Fuel Storage and Handling Even if a particular ATF design is unable to demonstrate verbatim compliance, the intent of these principal design and performance requirements should be satisfied or new requirements D

developed.

7.1 Regulatory Framework Applicability Assessment To prepare for forthcoming TRs and LARs, the staff determined the applicability of existing regulations and guidance for the near-term ATF concepts, higher burnup, and increased enrichment. Appendix A to this Project Plan, called the Regulatory Framework Applicability Assessment, provides the results of this assessment as of the time of issuance of this Project Plan revision. Each regulation and guidance document listed in Appendix A was assessed for whether it was fully applicable to ATF, higher burnup, and increased enrichment. If a regulation or guidance was found to not be fully applicable, the table identifies this fact and provides a justification. However, the need for regulation or guidance to be fully applicable to ATF, higher burnup, and increased enrichment varies. In some instances, it is not, possibly because other 23

regulations or guidance replace or supersede it. In other instances, it does need to be fully applicable. For some of these instances, NRC staff already discussed and agreed upon a path towards achieving full applicability for the relevant regulation or guidance, and Appendix A will state these closure paths. In other instances, a closure path has not yet been agreed upon, and Appendix A will indicate as such. Appendix A also makes note of some pertinent requirements or actions that regulations or guidance require of an applicant to ensure the regulation or guidance is correctly applied.

Appendix A is non-exhaustive and will be continually updated alongside new revisions to the Project Plan as more information is developed. If/when advancements in an ATF concept not listed on the table demonstrate that the concept could obtain commercial viability, the staff will perform the analysis for that concept.

The identification of a regulation or guidance that is not fully applicable does not mean that ATF, T

higher burnup, and increased enrichment reviews cannot be performed today; there are regulatory strategies that can be used to proceed forward with a review. For example, sensitivity studies utilizing NRC codes can be performed to ascertain the impact of parameters and their importance on predicting pertinent phenomena. Knowledge of these sensitivities 7.2 R

guide the NRC staff's requests for additional information, help with coming to a safety determination through understanding the range of a fuel designs performance, and help form the basis of any potential licensing conditions.

AF Licensing Pathways The tables in Appendix A, Regulatory Framework Applicability Assessment, provide the applicability of existing regulations and guidance for the near-term ATF concepts, higher burnup, and increased enrichment. The staff is developing licensing pathways that provide a simple depiction of the remaining tasks or informational needs for successful (i.e., timely) approval of TRs and plant-specific LARs. They will show the ideal plan or path forward given the current state of technical and regulatory progress in the specified ATF technology, higher burnup, and increased enrichment. As the industry and NRC staff develop more definitive D

timeframes for submittal of information or completion of tasks, a timeline will be added to the pathways.

The licensing pathways have their limitations. They are not all inclusive, meaning that they do not depict all items a vendor, the NRC staff, or a licensee would have to complete or include to successfully submit or review a TR or LAR. The pathways are also not a timeline, meaning they do not show how long it will take to review and approve a TR or a plant-specific LAR.

The licensing pathways are currently under development and will change as the staff better understand the remaining items/information needs and the timing of receipt from vendors or completion by NRC staff. Appendix B to this Project Plan provides the draft licensing pathway for higher burnup TRs and LARs. Licensing pathways for increased enrichment, coated cladding, and doped pellets are under development and will be shared with stakeholders at the 24

appropriate time. Pathways will be developed for the other ATF concepts when enough details are known to perform a regulatory framework applicability assessment for that concept.

7.3 Additional Considerations Aspects of ATF, higher burnup, and increased enrichment designs or implementation strategy could expand the scope, level of complexity, and schedule of the staffs review of TRs and LARs, such as the following:

Environmental concerns Changes in accident source term and operational source term Industry may take an incremental approach to higher burnup and increased enrichment Lack of technical data for independent confirmatory calculations T

Licensees seeking to adopt increased enrichment and higher burnup beyond the current licensed limits will need to submit a LAR with a complete description of the potential environmental impacts of the request. The staff review of these environmental impacts could be a source of additional complexity resulting in additional schedule risk. Specifically, the R

anticipated enrichment levels up to 10 weight-percent U-235 and burnup levels above 62 GWd/MTU are outside the conditions for use of Table S-4 (10 CFR 51.52(c)) for the environmental impacts of the transportation of fuel and waste. Thus, each LAR review would AF need a full description and detailed analysis performed by the staff of the environmental effects of transportation of fuel and waste to and from the reactor for these higher enrichment and burnup levels. Any such analysis would have to address a number of competing factors that could lower or raise environmental impacts such as batch core loads, increased refueling intervals, revised number of fuel assemblies per shipment, increases in radionuclide inventory, and others where the needed data has yet to be determined. There are also expected changes to the plant-specific safety analysis which also would require a corresponding environmental finding with the safety finding. As with the analysis of transportation of fuel and waste, each environmental review by the staff would need to evaluate the related plant-specific environmental impacts to provide information on any changes from previous environmental D

analyses, such as from license renewals. To minimize this additional complexity for each LAR, the staff may need to consider if it is possible to generically evaluate the environmental impacts.

To this end the staff is evaluating past studies, such as NUREG-1437 Addendum 1 and NUREG/CR-6703 along with assessing the available fuel performance analyses, data, and studies to determine if a generic study of ATF environmental impacts is feasible. The necessity of this effort will become clearer as NRC staff continues engagement with industry and the fuel vendors.

Accident tolerant fuel concepts may affect fission product release kinetics and chemical form, core melt progression and relocation, and mechanical and chemical interactions under severe accident conditions relative to 5 weight percent UO2 fuel in uncoated zirconium alloy cladding.

These effects may impact accident source term. Higher fuel burnup and increased enrichment may also effect changes in accident source term and operational source term via changes in 25

decay heat load and isotopic inventory. Should these source terms be impacted, licensees will need to evaluate the impact of the change to the accident analyses and offsite doses and may need to revise their accident analyses of record and environmental analyses. Additional challenges may exist if the revised source terms result in environmental impacts that are not captured in or bounded by the impacts discussed in NUREG-1437, Generic Environmental Impact Statement for License Renewal of Nuclear Plants, (ADAMS Accession No. ML13106A241). This could complicate successful completion of a finding of no significant impact for an exemption request. The NRC staff is performing MELCOR calculations for representative plants to determine whether existing source term guidance (e.g., Regulatory Guide 1.183 (ADAMS Accession No. ML003716792)) is applicable for near-term accident tolerant fuel concepts and for 5 weight percent UO2 fuel in zirconium alloy cladding over the increased ranges of burnup and enrichment being proposed. The results from the MELCOR calculations may result in a revision to RG 1.183 to incorporate the new information, if necessary.

T The staff understands industry may take an incremental approach in moving to higher burnup and increased enrichment. Therefore, the NRC staff envisions near-term and longer term strategies for moving forward with the licensing of higher burnup fuels and fuels with increased R

enrichment. In the near-term, licensees may need to request exemptions to existing regulations on a licensee-specific basis for the use of increased enrichment and demonstrate compliance with safety requirements along with the exemption criteria. Should widespread adoption of AF these technologies become apparent, the NRC staff may utilize rulemaking in a longer term strategy to update existing regulations on enrichment levels to facilitate a more predictable licensing process.

The independent confirmatory calculation capabilities highlighted in this Project Plan are used to expedite staff reviews. As discussed in Section 10 of this Project Plan, these capabilites are heavily dependent on material property and experimental data to ensure that a computer code appropriately models key phenomena and accurately predicts the parameters of safety importance. If this technical data is not received or is incomplete, the staff can account for uncertainties through the use of limitations and conditions for TRs and license conditions for D

LARs. Additionally, the staff can perform sensitivity analyses to determine which material or physical propertiese hav the greatest effect on safety and tailor the limitations and conditions accordingly.

7.4 Lead Test Assemblies LTA programs provide pool-side, post-irradiation examination data collection; irradiated material for subsequent hot-cell examination and research; and demonstration of in-reactor performance.

This characterization of irradiated material properties and performance is essential for qualifying analytical codes and methods and developing the safety design bases for new design features or new fuel designs.

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The NRC published a letter to the Nuclear Energy Institute on June 24, 2019, Clarification of Regulatory Path for Lead Test Assemblies, (ADAMS Accession No. ML18323A169) that documents the agencys position concerning criteria for the insertion of LTAs under 10 CFR 50.59 without additional NRC review and approval. LTA programs for ATF designs, higher burnup, increased enrichment may require LARs, depending on the scope of the LTA campaign and the licensing basis of the reactor.

7.5 Initiating Activity The staffs expenditures associated with developing regulatory strategies and the framework for design-independent ATF licensing began in fiscal year 2017 and will continue as long as DOE and industry actively pursue ATF, higher burnup, and increased enrichment development. The staffs expenditures to support design-specific regulatory hurdles will begin upon formal notification from a vendor of its intent to pursue licensing of a specific design.

7.6 Deliverables T

At this time, there are no additional PIRTs or literature reviews planned for in-reactor activities.

R However, if future developments result in planned literature reviews or PIRTs, the staff will follow the schedule below.

AF Table 7.2 Anticipated In-Reactor Deliverables*

Title Map of hazards and failure mechanism to GDC, regulations, and guidance documents.

Due Date (near term/longer term) 6-12 months from completion of the PIRT exercise or literature review Develop or revise guidance to address any identified 24-48/36-60 months from necessary changes. completion of the PIRT exercise or literature review DDevelop rulemaking to address any identified necessary changes.

24-48/36-60 months from identification of required change

• The technical lead is the NRR Division of Safety Systems, Nuclear Methods and Fuel Analysis Branch.

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8 TASK 2: REGULATORY FRAMEWORK FUEL FACILITIES, TRANSPORTATION, AND STORAGE The NRC regulations for fuel cycle activities of fuel cycle facilities (enrichment and fabrication facilities), radioactive material transportation, and spent fuel dry storage are found in 10 CFR Part 70, 10 CFR Part 71, and 10 CFR Part 72, respectively. The regulations identify general performance requirements and have been used for licensing a broad spectrum of fuel cycle facilities and for the certification of a broad spectrum of transportation packages and spent fuel storage casks. The NRC does not expect these regulations to need modification to accommodate the fabrication, transportation, or storage of ATF concepts, increased enrichment, and higher burnup.

For the front-end of the fuel cycle, which includes enrichment of the feed material, fuel assembly T

fabrication and transportation of feed material and fresh fuel assemblies, new cladding materials and increased enrichment may present new and unique technical and regulatory issues; however, current guidance, review plans, and regulatory criteria are adequate to address these issues. The NRC staff recognizes that licensing and certification actions related to the R

production and transportation of fresh fuel with new cladding materials and increased enrichment will occur in the near term; therefore, any issues or challenges must be addressed in the near-term for successful deployment. To prepare the agency to conduct near-term licensing AF and certification reviews of ATF concepts with or without increased enrichment, discussion of licensing and certification strategies and approaches between applicants and NRC staff will need to be undertaken. Any potential technical or policy issues the NRC staff identifies will be communicated to stakeholders promptly.

For the back-end of the fuel cycle, which includes transportation and storage of spent fuel at higher burnup and increased enrichment, the NRC staff will continue to monitor industrys initiatives and licensing actions for reactor operation, and assess whether revisions to current guidance, review plans, and regulatory criteria may be warranted. The NRC staff recognizes that licensing and certification actions related to the transportation and storage of such spent fuel will not occur in the near term. The NRC staff will engage with industry as plans on the D

back-end of the fuel cycle are developed and will update this plan accordingly.

This task contemplates the changes to the regulatory framework that may be required to support the implementation of increased enrichment, considering the technical and regulatory issues it presents. When considering the safe transportation of material for the front-end of the fuel cycle, the notable technical issue associated with increased enrichment pertains to nuclear criticality safety for UF6 transportation and fresh fuel assemblies. Fuel assemblies (both fresh and irradiated) that rely on the fuel assembly structural performance to remain intact under accident conditions and the criticality evaluation of a single UF6 package without using the exception in 10 CFR 71.55(g) are examples of the technical issues that fall under fuel integrity and nuclear criticality safety, respectively. Benchmarking criticality analyses for increased enrichment fuel and burnup credit analyses for spent fuel storage and transport are also examples of the technical issues that fall under nuclear criticality safety. The regulatory 28

framework changes that may be necessary to address each technical issue are likely to be different; however, the staff does not anticipate that such changes will need to be made before higher fuel burnup or increased enrichment fuel can be licensed or certified for general use in reactors. Additional information on these technical issues are discussed in detail in Section 8.1.4 of this Project Plan.

To prepare for the review of fuel facility licensing, transportation packages, and spent fuel storage designs, the NMSS staff determined the applicability of existing regulations and guidance for the near-term ATF concepts, higher burnup, and increased enrichment. Item numbers 24 through 35 of Appendix A to this Project Plan provides the results of this assessment as of the time of issuance of this revision.

The review guidance documents in Appendix A draw on industry experience in the fabrication, transportation, and storage of Zr-clad UO2 fuel with up to 5 weight percent enrichment and T

burnup up to approximately 62 GWd/MTU rod average (or equivalent). The NRC may need to supplement some of the guidance to address safety-related issues that could arise from ATF designs that involve different fuel or clad materials, higher burnup, increased enrichment, or changes in the processes and systems used to produce or manage the ATF. Potential areas for R

which review guidance may be expanded include criticality safety for systems with increased enrichment and/or higher burnup, fuel or cladding material properties that are used in the analysis of transportation or storage packages, and failure mechanisms that must be considered AF for irradiated fuel other than Zr-clad UO2. Two specific examples for which guidance may be developed are material properties for FeCrAl alloys and SiC materials that are used as ATF cladding.

The NRC staff will continue to monitor industry plans for enriching, fabricating and transporting unirradiated ATF fuel designs and for transporting and storing irradiated ATF, including those with increased enrichment and higher burnup. When the staff believes that supplemental information or guidance would facilitate the preparation and review of applications involving the fabrication, transportation, and storage of ATF designs, higher burnup, and increased enrichment, it will discuss this with stakeholders and take actions as needed.

D 8.1 Facility, Transportation, and Storage Reviews The regulatory reviews to support the development and batch deployment of ATF designs with and without increased enrichment will occur in several fuel cycle areas, which include production (enrichment and fuel fabrication), transportation of UF6 feed material, transportation of fresh fuel assemblies, storage of spent fuel, and transportation of spent fuel. The sections below discuss these various reviews.

8.1.1 Uranium Enrichment and Fuel Fabrication Facility Reviews The uranium enrichment facilities that produce enriched uranium, as well as the fabrication facilities that would produce near term ATF concepts with and without increased enrichment, 29

would conduct operations that are similar to currently licensed ones. However, to produce fuel with enrichments above the 5 weight percent uranium-235, these licensees will have to submit amendments to increase their licensed enrichment limits. Fuel fabrication operations that would use new processes for producing a different type of fuel material (e.g., uranium alloy or UN) are expected to submit amendments to address both increased enrichment as well as the new processes. Licensees will use the regulations at 10 CFR 70.72, Facility change and change process, to determine whether NRC approval is required before implementing a change for the fabrication of ATF.

The staff is currently engaged with licensees of fuel cycle facilities to understand the status of their plans and the anticipated timing of their license amendment submittals 8.1.2 Uranium Feed Material and Unirradiated Fuel Transportation Package Reviews T

For increased enrichment in UF6 feed material and fresh fuel assemblies, changes to the regulations are not necessary to accommodate industry plans; however, licensing and certification challenges may exist, as discussed below in Section 8.1.4.

The staff has reviewed and still expects vendors that are developing ATF to request approval of R

additional packages for transporting LTAs from the fabrication facilities to reactors for test irradiation. As the industry prepares for the batch loading of ATF both with and without AF increased enrichment, the staff expects to receive requests for the approval of transportation packages that allow large-scale (i.e., batch) shipment of uranium feed material (currently UF6) and unirradiated ATF assemblies. The staff will review these requests against the requirements of 10 CFR Part 71 and will use the guidance in NUREG-2216, Standard Review Plan for Transportation Packages for Spent Fuel and Radioactive Material: Final Report, (ADAMS Accession No. ML20234A651) to perform the safety reviews. The NRC staff has supported literature reviews and assessments of data needs that focus on criticality and shielding safety (code validation) and materials properties and performance of fuel cladding (See Section 11 of this Project Plan for a reference to the complete list of literature reviews). These literature reviews and data needs efforts are expected to help the staff develop additional regulatory guidance for transportation of fuel with alternative cladding types and increased enrichment, if D

required.

The staff is currently engaged with fuel cycle facility certificate holders to understand the status of their plans and the anticipated timing of their transportation certificate amendment submittals.

8.1.3 Irradiated Fuel Transportation Package and Storage Cask Reviews The agency expects any shipments of irradiated ATF LTAs or rods from ATF LTAs to be made in NRC-approved transportation packages. For large-scale shipment of irradiated ATF assemblies with or without higher burnup, the staff expects to receive requests for the approval of transportation packages under 10 CFR Part 71. For shipments of a limited number of shipments of irradiated LTAs over a limited timeframe, requests could be made under 10 CFR Part 71 (i.e., letters of special authorization), similar to that expected for unirradiated 30

LTAs. The NRC will review these requests against the requirements of 10 CFR Part 71, and the staff will use NUREG-2216 for the safety review.

If NRC-licensed reactors use ATF assemblies and later wish to move those assemblies into dry storage, such sites will need storage systems that are designed to contain irradiated ATF assemblies and are licensed under 10 CFR Part 72. The NRC will review these requests against the requirements of 10 CFR Part 72, and the staff will use NUREG-2215, Standard Review Plan for Spent Fuel Dry Storage Systems and Facilities - Final Report, ADAMS Accession No. ML20121A190) for the safety review. Future updates of this Project Plan will address such systems as the industrys plans become more certain.

The NRC staff plans to support PIRT efforts that focus on the identification and evaluation of material properties and fuel degradation mechanisms to support the review of transportation packages or storage systems for irradiated ATF. These PIRT efforts should help the staff T

develop additional regulatory guidance for irradiated ATF, if required.

The staff is currently engaged with fuel cycle facility certificate holders to understand the status of their plans and the anticipated timing of their certificate amendment submittals.

R 8.1.4 Potential Challenges AF Certain aspects of ATF designs with or without increased enrichment and higher burnup or fuel cycle implementation strategies could affect the scope, level of complexity, and schedule of the staffs review. This section discusses the potential challenges that may need to be addressed to efficiently license these designs.

The major fuel cycle changes that are possible as a result of ATF development include (1) increased enrichment (i.e., greater than 5 weight-percent U-235 enrichment), (2) higher burnup above 62 GWd/MTU rod average (or equivalent) (3) different fuel material (e.g., Cr--doped UO2, UN, or metallic fuel material), and (4) different cladding (e.g., FeCrAl, SiC, or coated Zr cladding). The number and nature of changes in these areas affect the effort D

required to review proposed fuel cycle changes. Table 9.1 identifies potential regulatory actions for the fuel cycle facilities and operations that might be required for these potential fuel cycle changes.

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Table 8.1 Potential ATF Fuel Cycle Action and Associated Regulatory Actions Potential Regulatory Actions at Affected Facilities/Operations Potential ATF Irradiated Fuel Fuel Cycle Enrichment Fuel Fabrication Transportation Dry Cask Storage Action Facility Facility Facility Increased License License amendment Applications for new or Applications for enrichment amendment to to manufacture amended new or amended produce higher enriched fuel transportation storage licenses or higher certificates for certificates of enrichment unirradiated, enriched compliance are material feed material (e.g., expected for uranium hexafluoride increased package), and enrichment Higher burnup Not Not applicable T unirradiated and irradiated fuel assemblies Applications for new or Applications for RAF Different fuel material applicable Facility changes amended transportation certificates for irradiated fuel assemblies with higher burnup Applications for new or that do not meet the amended criteria of transportation new or amended storage licenses or certificates of compliance are expected for higher burnup fuel Applications for new or amended storage licenses or 10 CFR 70.72(c) certificates for certificates of will require NRC unirradiated fuel and compliance for approval irradiated fuel ATF assemblies Different fuel Applications for new or Applications for Dcladding amended transportation certificates for unirradiated fuel and irradiated fuel new or amended storage licenses or certificates of compliance to store ATF assemblies The greater the differences between an ATF design and Zr-clad UO2, the more likely supplemental review guidance will be required and the more likely the review will require greater staff effort. As an example, one potential ATF fuel material, UN, is more susceptible to chemical reactions (e.g., water, air) than UO2. This hazard needs to be considered in the design and 32

operation of a facility that produces or stores this material, and the NRC staff will need to review such facility designs and safety controls as part of the licensing process.

8.1.4.1 Challenges for Transportation of Uranium Feed Material and Unirradiated Fuel The regulations in 10 CFR 71.55(g) grant an exception from the consideration of moderator intrusion for the transportation of UF6 enriched to 5 weight percent or less. Transportation of UF6 enriched to greater than 5 weight percent will require the design and certification of new packages, the modification of currently existing approved packages, an exemption from the regulations that require evaluation of a single package with optimum moderation for enrichments greater than 5 weight percent uranium-235.

In addition to challenges for approval of transport of UF6 at increased enrichment (greater than 5 weight percent), it should be noted that American National Standards Institute (ANSI) N14.1, T

Nuclear Materials Uranium Hexafluoride - Packagings For Transport, only applies to enrichments up to 5 weight percent uranium-235 for the 30B and 30C cylinders; however 12A/12B cylinders which can hold up to 460 pounds of UF6 are authorized for enrichments up to 12.5 weight percent uranium-235. DOT regulations in Title 49 of the Code of Federal R

Regulations (49 CFR) 173.420 state that UF6 packaging (whether fissile, fissile excepted, or non-fissile) must be designed, fabricated, inspected, tested and marked in accordance with American National Standard N14.1 that was in effect at the time the packaging was AF manufactured. DOT regulations in 49 CFR 173.417, which provide requirements for shipment of UF6 heels without a protective overpack also limit the enrichment of 30B and 30C cylinders to 5 weight percent uranium-235. In addition to an NRC approval for shipment in a packaging using a 30B or 30C cylinder, a special permit from DOT will be needed, if an exemption to the NRC requirements are used for approval.

Benchmarking criticality analyses for fissile material enriched to greater than 5 weight percent uranium-235 presents a challenge due to the limited number of critical experiments in that range. Applicants for package approval could potentially overcome this challenge by:

D

performing new critical experiments to validate criticality calculations for 5-10 weight percent uranium-235, relying on sensitivity/uncertainty analysis methods to develop new critical experiments, relying on sensitivity/uncertainty analysis methods to determine that existing experiments are applicable to 5-10 weight percent uranium-235, increasing the one-sided k-effective tolerance factor to account for uncertainties in criticality code performance due to the number of applicable critical experiments for benchmarking, or using some combination of the above options.

In addition, applications to transport unirradiated ATF for batch loading may credit the structural properties of the fuel cladding to maintain the configuration of the fuel during normal conditions of transport and hypothetical accident conditions. While coated zirconium cladding is expected to have properties similar to those of conventional zirconium cladding, confirmatory data on ATF 33

cladding mechanical properties and fatigue performance will likely be needed to support the safety analyses. Similarly, applications to transport fuel that uses other cladding materials (e.g.,

FeCrAl, SiC) will need to be accompanied by data to demonstrate adequate structural performance.

8.1.4.2 Challenges for Transportation and Storage of Spent Fuel A transportation package or storage cask that is evaluated containing spent fuel will have the same criticality benchmarking concerns listed above for unirradiated material. If a transport package or storage cask is evaluated for burnup credit, instead of conservatively evaluating it as fresh fuel, the isotopic depletion analyses will need to be validated for the increased enrichment and burnup levels. In addition to validating the criticality analysis, the accuracy of depletion calculations to calculate the source term for the shielding analyses should be evaluated for burnup greater than 62 GWd/MTU rod average (or equivalent).

T In addition, the data needs for fuel cladding performance discussed above are also present for irradiated cladding. Cladding mechanical properties are influenced by in-reactor irradiation and the vacuum drying operations that are performed when the fuel assembles are loaded into the R

transportation or storage casks. Increased levels of burnup and new fuel pellet compositions can also influence cladding stresses and, consequently, affect cladding performance during fuel loading, transportation, and storage operations. Further, the thermal metrics in the NRC AF guidance for allowable cladding temperatures are not necessarily applicable to ATF. Applicants for transportation package and storage cask approval could potentially overcome these challenges by:

providing data from mechanical property and fatigue tests of ATF cladding irradiated to the requested allowable burnup (e.g., from LTAs) providing data to justify allowable cladding temperatures during drying operations, considering the effects of cladding creep and potential mechanical property changes providing data to justify the thermal properties of ATF cladding that are used in the transportation package or storage cask thermal analyses D

Applications to renew dry storage system licenses and certificates of compliance must also evaluate and, if applicable, propose an aging management approach for aging-related degradation of ATF cladding. NUREG-2214, Managing Aging Processes In Storage (MAPS)

Report: Final Report, (ADAMS Accession No. ML19214A111) includes an evaluation of aging mechanisms for traditional Zr-clad fuel; these evaluations are not necessarily applicable to ATF.

As a result, the NRC staff expects that a renewal application provide data to demonstrate that age-related phenomena not at play during extended dry storage of spent ATF.

8.1.5 Initiating Activity The staffs expenditures associated with developing regulatory strategies and the framework for design independent ATF fuel cycle licensing began in FY 2017 and will continue as long as 34

DOE and industry are actively pursuing ATF, higher burnup, and increased enrichment development. The staffs expenditures to support ATF designs and licensee-specific fuel cycle activity begins when an applicant meets with the staff to discuss its proposed submittal, or when the staff receives an application to review.

8.1.6 Deliverables At this time, there is one PIRT that is planned for spent fuel transportation and storage activities.

Table 8.2 Anticipated Fuel Cycle, Transportation and Storage Deliverables*

Title Due Date (near term/longer term)

PIRT on cladding performance during spent fuel transportation FY 2023 and storage Develop or revise guidance to address any identified necessary changes.

T 24-48/36-60 months from completion of the PIRT exercise or literature review R

• The technical lead is the NMSS Division of Fuel Management AF D

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9 TASK 3: PROBABILISTIC RISK-ASSESSMENT ACTIVITIES The NRC uses probabilistic risk assessments (PRAs) to estimate risk to investigate what can go wrong, how likely it is, and what the consequences could be. The results of PRAs provide the NRC with insights into the strengths and weaknesses of the design and operation of a nuclear power plant. PRAs cover a wide range of NRC regulatory activities, including many risk-informed licensing and oversight activities (e.g., risk-informed technical specification initiatives, the significance determination process portion of the Reactor Oversight Process).

These activities make use of both plant-specific licensee PRA models and plant-specific NRC PRA models. The NRC uses the former models predominantly for licensing and operational activities and the latter models predominantly for oversight activities. A key tenet of risk-informed decision-making is that these models reflect the as-designed, as-operated plant.

For this reason, these models should be updated to reflect significant plant modifications. The introduction of significantly different fuel into the reactor core has the potential to affect these T

models, particularly once the reactor core composition significantly influences the plants response to a postulated accident (e.g., time to fuel heat up and degradation, amount of total hydrogen generation, higher decay heat from increased enrichment).

R Activities associated with the development of capabilities to support risk-informed regulatory activities following the implementation of ATF, higher burnup, and increased enrichment could require significant NRC resources. Information about the industrys intended approach is AF needed to create a meaningful plan. Early interactions within the PRA community on ATF, higher burnup, and increased enrichment activities, including early preapplication meetings, have been used to encourage industry to ensure that the approach being pursued is consistent with the related regulatory requirements and staff guidance. This plan recognizes that the staffs PRA-related preparatory work involves two separate, but closely related, aspects:

(1) The staff need to prepare for, and review, PRA-related information submitted as part of the licensing process for batch loading of ATF, higher burnup, increased enrichment, and incorporation of the safety enhancements of ATF into the licensing basis.

D (2) The staff need to develop PRA-related capabilities that allow it to do the following effectively:

Review risk-informed licensing applications and ensure that applicants are using acceptable PRA models once ATF, higher burnup, and/or increased enrichment is implemented.

Perform risk-informed oversight evaluations (e.g., significance determination process) once ATF, higher burnup, and/or increased enrichment is implemented.

The nature of item 1 is highly dependent on the approach taken by each vendor or licensee, or both, in its licensing application. However, item 2 is somewhat independent of the licensing approach for the batch loading of ATF; therefore, this plan currently focuses more attention on item 2.

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As illustrated by the above categorization, PRA is more broadly relevant to ATF than simply the incorporation of ATF safety enhancements into the licensing basis. Again, this stems from the fact that the NRC uses a risk-informed licensing and oversight approach that relies on plant-specific PRAs that represent the as-built and as-operated plant. Near-term ATF designs may have a limited impact on PRA modeling, whereas longer term ATF designs may have a more significant impact on PRA modeling. Incremental increases in fuel burnup and enrichment (such as increases on the orders of tenths of a percent enrichment or low single digits of gigawatt days per metric ton of burnup) may have only a limited (or no) impact on PRA modeling. However, the more appreciable increases in fuel burnup and enrichment that are anticipated, especially in combination with the other cladding and fuel changes associated with adoption of ATF, may have a more significant impact on PRA modeling. In general, the PRA modeling changes in question include the following:

T selection of core damage surrogates used in defining PRA end states (e.g., peak nodal clad temperature of 1,204 degrees Celsius, water level at two-thirds active fuel height) accident sequence modeling assumptions used to create event tree models that define the high-level successes and failures that can prevent core damage (e.g., late

R containment venting is required for avoiding core damage) system success criteria used in fault trees for defining the minimum hardware needed to fulfill specific mitigation functions (e.g., two relief valves are needed to prevent injection AF pump deadhead when feed and bleed cooling is used for a transient with no feedwater) sequence timing assumptions used in accident sequence modeling, success criteria determinations, and human reliability analysis to establish relevant time windows (e.g., feed and bleed cooling initiated within 20 minutes of low steam generator water level).

The staff will need to ensure that licensees PRAs continue to use acceptable models and assumptions as part of the implementation of ATF and update the NRCs models (as necessary) to reflect the ATF plant modifications, higher burnup, and increased enrichment. PRA models are not required under 10 CFR Part 50 and their use is not a prerequisite for approval of an ATF D

design, higher burnup, increased enrichment, or the batch loading into a particular plant. That said, plants using PRA to support risk-informed operational programs (e.g., 10 CFR 50.69, risk-informed TS initiatives) should continue to update their PRAs so that they realistically reflect the as-built, as-operated plant. The NRC expects that modifications affecting a plants risk profile (e.g., ATF, improved reactor coolant pump seals, etc.) will be incorporated into licensees PRA models under their existing PRA maintenance programs.

Much of the needed underlying deterministic knowledge to address these points can leverage the work covered elsewhere in this plan, particularly the fuel performance, thermal hydraulics, and severe accident calculation capability development. It is envisioned that much of the analytical investigation needed to assess PRA-related impacts and support PRA-related changes in the agencys SPAR models can use the MELCOR modeling and analysis discussed in Section 10 of this Project Plan. If needed, additional confirmatory analysis could also be 37

pursued using MELCOR plant models developed for other NRC initiatives, such as those documented in NUREG-1953, Confirmatory Thermal-Hydraulic Analysis to Support Specific Success Criteria in the Standardized Plant Analysis Risk ModelsSurry and Peach Bottom, (ADAMS Accession No. ML11256A023), and NUREG-2187, Confirmatory Thermal-Hydraulic Analysis to Support Specific Success Criteria in the Standardized Plant Analysis Risk Models Byron Unit 1, (ADAMS Accession Nos. ML16021A423 and ML16022A062). This leveraging of resources between severe accident analysis tools and PRAs is routine.

In the nearer term, PRA-related impacts can be assessed using the general knowledge being developed in these other ATF Project Plan areas in conjunction with one or more pilot efforts using the existing SPAR models. Such pilots would help gain risk insights, assess the potential changes in core damage frequency (CDF) and large early release frequency (LERF),4 and highlight areas where existing guidance5 or methods may require refinement to address the implementation of ATF, higher burnup, and increased enrichment.

T As a final introductory point, engagement on PRA-related topics both within the staff and with external stakeholders is important at all stages. Effective interaction will foster a common understanding of the acceptability of PRA methods used to model plant modifications and the R

impact that will ultimately be realized when these modifications are integrated into PRAs and risk-informed processes. Effective interaction can also ensure that information required to develop PRA modeling assumptions related to plant modifications is properly coordinated with AF the deterministic review. In this case, PRA relevance has been identified early in the process, and time is available to address the PRA-related needs in a thoughtful and symbiotic manner.

D 4 Differences in LERFs could occur because of (1) differing fuel heatup and degradation time windows, (2) the generation of differing amounts of in-vessel hydrogen, (3) changes to the fission product release rates, and (4) shifts in the balance of challenges to other vessel and connected piping system components stemming from higher in-core temperatures before the relocation of debris.

5 This guidance encompasses the guidance used in risk-informed licensing and oversight (e.g., the SRP; relevant RGs; Inspection Manual Chapter (IMC) 0609, Significant Determination Process, dated April 29, 2015; the risk-assessment standardization process manual). In reality, most of this guidance would not require revisions because the concepts and processes would continue to apply. However, some aspects could require modifications, such as those involving the LERF multipliers used in IMC 0609, Appendix H, Containment Integrity Significance Determination Process, dated May 6, 2004, whereas some guidance may benefit from additional discussion of ATF impacts.

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For the purpose of identifying the PRA-related milestones, the following key assumptions are necessary (some restate assumptions made elsewhere in this plan):

The timing of PRA-related efforts will be cross-coordinated with those of the previously identified partner areas (e.g., severe accident analysis) to allow the leveraging of deterministic work to make the PRA-related efforts efficient. This approach will be reassessed as the industrys perspective evolves on the potential risk significance of ATF designs, higher burnup, and increased enrichment, as they relate to future submittals aimed at leveraging ATF to reduce regulatory requirements.

This plan does not account for new regulatory initiatives that might be requested to maximize the operational or economic benefit of ATF, such as the following:

modifications to the categorization process in 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems and Components for T

Nuclear Power Reactors, associated with the use of relative (as opposed to absolute) CDF/LERF criteria6 reduction of requirements associated with security and emergency preparedness programs R

AF rulemaking initiatives that might be requested to facilitate rapid adoption of increased enrichment.

D 6 This initiative has been mentioned as a potential limitation in the degree of benefit that would be gained in risk-informed licensing space, and it contrasts to the use of absolute risk measures in other relevant risk-informed licensing activities such as risk-informed technical specification initiatives.

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Table 9.1 PRA ActivitiesMilestones Lead Milestone Input Needed Time/ Needed By Duration Participate in internal and external N/A Ongoing N/A discussions and knowledge 1 development related to ATF (e.g., internal working group meetings, public meetings)

Complete licensing reviews, More information TBD TBD including potential TRs or industry regarding the specific guidance, related to the licensing approach 2

risk-informed aspects of ATF, higher burnup, and increased enrichment licensing Complete a SPAR pilot (as necessary) of a near-term ATF design, higher burnup, or increased T

Deterministic knowledge base being developed 6 months 1 year before the first near-term 3

4 R

enrichment for a boiling water reactor (BWR) and pressurized water reactor (PWR) subject plant to AF assess CDF/LERF impacts, gain risk insights, and identify potential improvements to guidance Complete a SPAR pilot (as necessary) of a longer term ATF design for a BWR and PWR subject plant to assess CDF/LERF impacts, under other tasks (e.g., MELCOR analysis)

Deterministic knowledge base being developed under other tasks 6 months2 ATF core load1 1 year before the first longer term ATF core load1 gain risk insights, and identify (e.g., MELCOR potential improvements to guidance analysis)

Update guidance (as necessary) to Completion of the 1 year Before the D 5 6

support licensing and oversight functions for plants making modifications (if necessary) for ATF, higher burnup, or increased enrichment Update agency PRA models to reflect ATF-related changes to the as-built, as-operated plant for items above Details of the plant modifications 1 year3 ATF core load1 As needed to support the agencys risk relevant plants/models evaluations 1 Here, core load means the replacement of a large proportion (e.g., 50 percent or more) of the core with ATF assemblies, assuming that non-ATF fuel will be generally more limiting to PRA impacts if a mixed core exists.

2 This task should be performed sequentially after the equivalent task for near-term ATF designs as long as both near -term and longer term designs are of regulatory interest.

3 This would occur after approval of the associated licensing action.

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Table 9.2 PRA ActivitiesDeliverables Title Lead Time Safety evaluation contributions for TRs and LARs related TBD to ATF Report documenting results and recommendations from a 1 year before the first near--term near-term ATF SPAR pilot study ATF core load Report documenting results and recommendations from a 1 year before the first longer longer term ATF SPAR pilot study term ATF core load Updated guidance (e.g., risk-assessment standardization Varies depending on the project guidance changes) to support licensing and documents that require oversight functions for plants making ATF-related modifications modifications Updated agency PRA models to reflect ATF-related T

changes to the as-built, as-operated plant for relevant plants/models As needed to support the agencys risk evaluations 10 R

TASK 4: DEVELOPING INDEPENDENT CONFIRMATORY CALCULATION CAPABILITIES AF Independent confirmatory calculations are one of the tools that the staff can use in its safety review of TRs, LARs, and front-end and back-end licensing actions. Confirmatory calculations provide the staff insight on the phenomenology and potential consequences of transient and accident scenarios. In addition, sensitivity studies help to identify risk significant contributors to the safety analyses and assist in focusing the staffs review. RG 1.70, Revision 3, Standard Format and Content of Safety Analysis Reports for Nuclear Power Plants (LWR Edition),

(ADAMS Accession No. ML011340122) identifies the standard format and content of safety analysis reports for nuclear power plants, and the SRP identifies the criteria that the staff should use to review licensee safety analyses. The NRC plans to continue to develop independent confirmatory analysis tools that support robust SEs and provide insights into safety significant D

factors for each ATF design, higher burnup fuels, and fuels with increased enrichment. Vendor codes used for ATF, higher burnup, and increased enrichment modeling capabilities will likely be based on smaller data sets than those of the current Zr-UO2 models. This will result in greater uncertainty in the results of the safety analyses and the margins to the specified acceptable fuel design limits. For these reasons, confirmatory calculation capabilities will be critical for generating confidence in the safety assessment of ATF, higher burnup, and increased enrichment against all applicable regulatory requirements. A confirmatory code can be used to independently quantify the impact of modeling uncertainties and support more efficient reviews with the potential for fewer requests for additional information. Finally, the experience and insights gained by developing an in-house code can be leveraged in reviews of externally developed models and methods, thus making reviews more efficient and effective.

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The staff identified four technical disciplines needing calculation capability development to support safety reviews: (1) fuel performance, (2) thermal hydraulics, (3) neutronics, and (4) severe accidents. The NRC has developed a suite of codes to analyze these disciplines, and they have been used successfully to support regulatory decision-making. Further development of these codes is appropriate to ensure that the NRC has the capability to analyze ATF designs, higher burnup, and increased enrichment. Having tools that the staff can use to analyze ATF, higher burnup, and increased enrichment will be particularly important because applicants will use computational tools to demonstrate that they have met fuel safety acceptance criteria and because, in some cases, the properties and models for ATF, higher burnup, and increased enrichment within the computational tools will be based on limited experimental data.

The development of calculation capabilities will proceed with similar activities in each area, as follows:

T PIRT exercises help ensure that all new phenomena important to safety have been identified and considered in the planning phases. PIRT results will be used to inform code development efforts.

Scoping studies or code evaluations will be performed to identify the architecture and

R model updates needed to model various ATF concepts and designs.

Where necessary, code architecture modifications will be made (e.g., to remove Zr/UO2 hard-wired properties and assumptions or to solve the governing equations for AF non-cylindrical geometry).

Material properties will be added, and new models will be developed, where necessary.

Integral assessment of the updated codes will be completed and documented. It is likely that results from integral assessments and uncertainty studies performed using updated codes will be used to revisit and maintain PIRT products.

Figure 10.1 depicts a generic schematic of tasks associated with developing calculation capabilities for near-term ATF, higher burnup, and increased enrichment, whether such capabilities are developed by the applicant, DOE, or the NRC.

D Figure 10.1 Development process for near -term calculation capability Figure 10.1 shows that code development requires testing and data to feed model development and validation. Developing codes to demonstrate that ATF, higher burnup, and increased enrichment can be used safely includes updating codes with ATF, higher burnup, and increased enrichment material properties and models and then validating the updated codes against 42

relevant experimental data. The validation exercise ensures that a code appropriately models key phenomena and accurately predicts the parameters of safety importance. The datasets used to develop models often come from separate effects testing (i.e. mechanical properties testing, autoclave testing), whereas code assessment and validation often use data generated in integral effects (i.e. irradiation campaigns, loss of coolant accident testing, reactivity-initiated-accident testing) test programs.

Much of the work to update the aforementioned codes for near-term ATF concepts has been completed. The NRC has sponsored two PIRTs to date, covering the behavior of chromium-coated zirconium-alloy cladding in-reactor operating and accident conditions (ADAMS Accession No. ML19172A154) and for the behavior of ATF in severe reactor accident conditions (ADAMS Accession No. ML21113A277). The NRC has also sponsored literature reviews have been completed to compile relevant information for the performance of ATF in reactor, transportation, and storage conditions; more information can be found on the NRCs public T

website. Furthermore, the NRC has updated the architecture of its codes to make them more flexible and to more easily implement new material property models. This means that once experimental data becomes available, the NRC can quickly add new models to the code.

Again, the NRC is relying on the nuclear fuel vendors and on the U.S. Department of Energy to R

provide the data needed to implement new material properties and to validate the codes.

Although this plan addresses calculation capability development in four different disciplines, AF technical overlap between disciplines exists, including the introduction of new material properties. To reduce duplication of effort, the analysis tools will be coupled to allow codes to send and receive information between each other. For example, neutronics codes can be used to provide fuel performance codes with pellet radial power distribution information as a function of burnup, and fuel performance codes can provide neutronics codes with fuel temperature and deformation calculations. Thus, coupling the codes leverages information sharing to improve the overall analysis capabilities and ensures consistency across codes. Where possible, the NRC will coordinate with DOE to reduce duplication of effort in calculation capability development.

D 11 COMPLETED PREPARATORY ACTIVITIES The NRC staff has completed many activities in preparation for ATF, higher burnup, and increased enrichment submittals. Additionally, the NRC is performing and has completed multiple reviews for ATF, higher burnup, and increased enrichment submittals. The complete list of these public activities can be found on the NRCs ATF public website:

https://www.nrc.gov/reactors/atf.html 43

The website contains the following collections of ongoing and completed activities:

The ATF-related licensing actions page provides all submitted ATF, higher burnup, and increased enrichment licensing actions and the completed NRC review, if applicable.

This page can be found at:

https://www.nrc.gov/reactors/atf/licensing-actions.html The ATF-related documents page provides a listing of all NRC-issued public documents relevant to ATF, higher burnup, or increased enrichment subjects that are not reviews of industry submittals. This page can be found at:

https://www.nrc.gov/reactors/atf/related-docs.html The public interactions page provides a listing of all public meetings held since April be found at:

T 2018 that are related to ATF, higher burnup, and increased enrichment. This page can https://www.nrc.gov/reactors/atf/public-interact.html R

The NRC staff has completed significant work regarding international cooperation and coordination. The completed and ongoing international work can be found on the ATF website international page, which can be found at:

12 AF https://www.nrc.gov/reactors/atf/international-interact.html PATH FORWARD This Project Plan represents the high-level strategy to prepare the NRC for conducting efficient and effective reviews of ATF designs. The plan is intended to be a living document that may evolve as industry plans are refined and the state of knowledge for ATF concepts advances.

The staff will develop concept-specific licensing roadmaps when necessary to clearly identify the regulatory criteria which must be satisfied for approval.

D The staffs priority, now that this plan has been finalized, is to: 1) engage directly with the nuclear fuel vendors pursuing near-term ATF concepts, higher burnup, and increased enrichment with the objective of understanding the nexus between the phenomena identified as important to safety and their testing plans, and 2) understand the areas of margin recovery or operational flexibility that licensees plan to seek such that staff can begin to proactively refine the regulatory framework where necessary.

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APPENDIX A: REGULATORY FRAMEWORK APPLICABILITY ASSESSMENT As stated in Section 7 of the Project Plan, the NRC the staff determined the applicability of existing regulations and guidance for the near-term ATF concepts, higher burnup, and increased enrichment. Each regulation and guidance document listed in Appendix A was assessed for whether it was fully applicable to ATF, higher burnup, and increased enrichment.

If a regulation or guidance was found to not be fully applicable, Table A.1 identifies this fact and provides a justification. However, the need for regulation or guidance to be fully applicable to ATF, higher burnup, and increased enrichment varies. In some instances, it is not, possibly because other regulations or guidance replace or supersede it. In other instances, it does need to be fully applicable. For some of these instances, NRC staff already discussed and agreed upon a path towards achieving full applicability for the relevant regulation or guidance, and T

Table A.1 will state these closure paths. In other instances, a closure path has not yet been agreed upon, and Table A.1 will indicate as such. Table A.1 also makes note of some pertinent requirements or actions that regulations or guidance require of an applicant to ensure the regulation or guidance is correctly applied.

R Table A.1 is non-exhaustive and will be continually updated with each new version of the Project Plan as more information is developed. If/when advancements in an ATF concept not listed on AF Table A.1 demonstrate that the concept could obtain commercial viability, the staff will perform the analysis for that concept.

Table A.1 Key Green: actions or requirements for NRC Blue: information needs from industry Fully applicable: indicates that the document can be applied to the concept Not fully applicable: the document or parts of the document may not be applied to the concept, reasons for which are detailed below MHA: maximum hypothetical accident D

LOCA: loss of coolant accident RIA: reactivity initiated accident BU: burnup FGR: fission gas release FFRD: fuel fragmentation, relocation, and dispersal IFBA: integral fuel burnable absorber ID: inner diameter HC PIE: hot cell post irradiation examination RXA: recrystallized ISG: interim staff guidance A-1

Table A.1: REGULATORY FRAMEWORK APPLICABILITY ASSESSMENT 235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets RG 1.183 AST Fully applicable Fully applicable Fully applicable Fully applicable Fully applicable Draft Revision 1 No data gaps No data gaps No data gaps No data gaps No data gaps 1

Analytical guidance for predicting dose RG 1.183 AST Not fully applicable Not fully applicable Fully applicable Fully applicable Fully applicable Draft Revision 1 Reason: Reason: SAND- No data gaps No data gaps No data gaps Fragmentation- 2011-0128 is not MHA / LOCA source terms D

induced FGR of high burnup fuel validated to 75 GWd/MTU pellets may change Closure: Re-analysis MHA/LOCA source of SAND-2011-0128 term and timing of to higher BU is being releases Closure: Informal assistance request R conducted by RES and Sandia National Laboratory through (IAR) out to RES to 75 GWd/MTU address this Priority: Medium Priority: High (near- (Medium-term) 2 term) Reason:

Fragmentation-induced FGR of high burnup fuel pellets may change AF MHA/LOCA source term and timing of releases Closure: Informal assistance request (IAR) out to RES to address this T

Priority: High (near-term)

A-2

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets RG 1.183 AST Not fully applicable Not fully applicable Analytical Fully applicable Not fully Draft Revision 1 Reason: Analytical procedure procedure remains No data gaps applicable Fragmentation- remains applicable applicable Analytical Non-LOCA steady- induced FGR of Tables 3 and 4 not Tables 3 remains procedure state and transient high burnup fuel applicable applicable remains releases pellets may change Note: FAST is not Note: With respect applicable Non-LOCA steady validated up to 75 to Table 4, extent Tables 3 and 4 not state and transient GWd/MTU. RES is of 235U enrichment applicable source term working on the in RIA empirical Note: FAST is not Closure: Technical validation of FAST database unknown. validated for bases document in models to higher doped fuel. RES is D

development to address this gap.

burnup. A data needs report has working on validation of FAST Priority: High (near- been issued from models to doped term) RES to examine fuel. A data what specifically is needs report has R needed to expand the FAST been issued from RES to examine capabilities to 75 what specifically is 3

GWd/MTU needed to expand (medium-term the FAST priority). capabilities to Reason: doped pellets Fragmentation- (medium-term induced FGR of priority).

high burnup fuel Reason: RIA pellets may change transient FGR for AF source term doped fuel has not Closure: Technical been well bases document in quantified progress to address Closure: RIA this gap. transient FGR Priority: High (near-term)

T measurements on doped fuel are Reason: Reactivity necessary initiated accident (RIA) transient fission gas release A-3

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets (FGR) is not currently well quantified up to 75 GWd/MTU Closure: RIA transient FGR measurements are necessary RG 1.195 Not fully applicable Not fully applicable Fully applicable Not fully applicable Not fully Release fractions Reason: Validated Reason: Validated No data gaps Reason: Non- applicable from TID-14844 only up to 62 only up to 62 LOCA accident Reason: Non-D GWd/MTU for non-LOCA accidents GWd/MTU for non-LOCA accidents release fractions are not validated LOCA accident release fractions Closure: No closure Closure: No closure for doped fuel are not validated necessary. Higher necessary. Higher pellets for doped fuel BU release fractions BU release fractions Closure: No pellets 4

and source term to be addressed by RG 1.183 Rev. 1 R and source term to be addressed by RG 1.183 Rev. 1 closure necessary.

Analytical procedure outlined Closure: No closure necessary.

in RG 1.183 Rev. 1 Analytical can be applied to procedure doped fuel. outlined in RG 1.183 Rev. 1 can be applied to doped fuel.

RG 1.236 Fully applicable Not fully applicable Not fully applicable Not fully applicable Not fully AF PWR Control Rod No data gaps Note: Empirical Reason: Stated Reason: Stated applicable Ejection (CRE) and database limited applicability limited applicability is Reason: Stated BWR Control Rod beyond 68 to 5.0 wt%. limited to current applicability is Drop (CRD) GWd/MTU. Increased LWR fuel rod limited to current Accidents enrichment will designs LWR fuel rod 5 Reason: FFRD as a result of HBU and possible loss of T

promote higher rod worth and peaking Note: Thin coating designs will not significantly Reason: doped coolable geometry factors alter fuel rod fuel RIA during RIA has not Note: Extent of 235U response. Cladding performance has been well quantified enrichment in RIA failure thresholds not been well or understood and damaged core quantified.

A-4

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets Closure: RIA data empirical database coolability limits Closure: Data for on high and unknown. remain applicable. irradiated, doped increased burnup No data gaps UO2 fuel pellets fuel rod segments Note: Guidance and IFBA fuel with deposited states that coated pellets needed to energy beyond claddings will be better understand predicted cladding addressed on a impact of additive damage needed to case-by-case basis agents (e.g.,

investigate FFRD larger grain size, and loss of coolable retained fission geometry. Ideally, gas, grain D these data should also include boundary hold-up, thermal transient FGR. conductivity) on Reason: HBU cladding failure effects on RIA not thresholds, well quantified. FFRD, transient R HBU cladding failure thresholds FGR, and coolable should be defined. geometry.

Closure: RIA data Note: Guidance on high and states that doped increased burnup pellets will be fuel rod segments, addressed on a especially RXA case-by-case cladding, with low basis corrosion needed to AF better understand burnup-effects and define cladding failure thresholds.

T A-5

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets 10 CFR 50.46 Applicable* Applicable* Fully applicable Not fully applicable Not fully LOCA Prescriptive Note: As written, it is Note: As written, it is Reason: As per applicable Analytical fully applicable. The fully applicable. The 50.46(a)(1)(i), Reason: As per Requirements NRC staff has NRC staff has 50.46 is only 50.46(a)(1)(i),

identified that recent identified that recent applicable to 50.46 is only research findings research findings zircaloy or ZIRLO applicable to UO2 concerning burnup- concerning burnup- cladded fuel. fuel effects are not effects are not Closure: The staff Closure: The staff addressed. Draft addressed. Draft still require that the still require that rule 50.46c rule 50.46c prescriptive the prescriptive addresses these addresses these analytical analytical 6

D burnup-effects Note: Ideally, burnup-effects Note: Ideally, requirements be met. Exemptions requirements be met. Exemptions industry submittals industry submittals requests will have requests will have should discuss the should discuss the to be submitted. to be submitted recent LOCA recent LOCA Refer to coated and it should be cladding ISG demonstrated findings per NUREG/CR-7219.

R findings per NUREG/CR-7219. (ML19343A121). whether the prescriptive analytical limits are impacted by the proposed additive fuel concept.

LOCA Embrittlement Fully applicable Fully applicable Fully applicable Fully applicable Fully applicable Research Findings Large population of Large population of No data gaps Rate for oxidation Large population AF fuel rods beyond fuel rods beyond and embrittlement of fuel rods

- Draft RG 1.222 threshold for threshold for different from bare beyond threshold

- Draft RG 1.223 cladding ID oxygen cladding ID oxygen zirconium for cladding ID

- Draft RG 1.224 embrittlement. embrittlement. Note: Single sided oxygen 7 steam oxidation embrittlement T data and subsequent Note: Hot cell (HC) post mechanical data as irradiation well as double examination (PIE) sided integral data needed to steam oxidation define threshold A-6

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets data and for fuel-clad bond subsequent layer.

mechanical data are necessary to establish PQD limits.

STS (STSB) TS 4.2.1 and 4.3.1 TS 4.2.1 and 4.3.1 TS 4.2.1 is fully TS 4.2.1 is fully TS 4.2.1 is fully are fully applicable are fully applicable applicable pending applicable applicable B&W: No data gaps No data gaps the outcome of the Note: Licensees Note: Licensees Figure 3.7.16-1 following: should revise TS should revise TS 4.2.1 4.3.1.1 D

Figure 3.7.16-1, 3.7.17-1, and Figure 3.7.16-1, 3.7.17-1, and NRC and TSTF to discuss whether or 4.2.1 to specify chromium coated 4.2.1 to specify doped pellets.

4.3.1.2 3.7.18-1 are fully 3.7.18-1 are not the term cladding.

applicable applicable slightly in TS Westinghouse: Note: Licensees Note: Licensees 4.2.1 includes fuels Figure 3.7.17-1 enriched beyond 4.2.1 4.3.1.1 should provide R

plant-specific figure should provide plant-specific figure 5%

for TS with LAR. for TS with LAR.

8 4.3.1.2 CE:

Figure 3.7.18-1 4.2.1 4.3.1.1 4.3.1.2 AF GE:

4.2.1 4.3.1.1 4.3.1.2 9

10 CFR 50.67 Accident Source T

Potential impacts to accident source term described above for RG 1.183 Revision 1.

Term 10 CFR 50.68 Fully applicable Fully applicable Not fully applicable Fully applicable Fully applicable 10 Criticality Accident No data gaps No data gaps Reason: 5 wt% No data gaps No data gaps Requirements enrichment limit A-7

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets (without criticality monitoring system) explicitly stated Closure:

Exemption requests and/or rulemaking to be conducted Priority: High Note: Alternatively, licensees can D adopt 70.24 Note: Criticality analyses may need to be updated.

10 CFR 50 Appendix K: ECCS Evaluation Models Reason: Appendix K R

Not fully applicable Not fully applicable Reason: Appendix K Fully applicable No data gaps Not fully applicable Reason: The Fully applicable No data gaps is not fully is not fully Baker-Just metal-applicable to the applicable to the water reaction rate current BU limit of current BU limit of correlation is not 62 GWd/MTU. For 62 GWd/MTU. For applicable to example, thermal example, thermal coated cladding, as conductivity conductivity it was developed degradation (TCD) degradation (TCD) for bare zircaloy is not addressed. is not addressed. cladding TCD occurs under TCD occurs under Closure: An 11 AF HBU conditions. HBU conditions. oxidation kinetics More information on More information on model based on TCD is available in TCD is available in chrome-coated Information Notice Information Notice cladding should be (IN) 2009-23 (IN) 2009-23 developed. If the (ML091550527 and ML121730336).

(ML091550527 and ML121730336).

T benefits of the coating are not to Closure: TBD Closure: TBD be realized and the Reason: FFRD is Reason: FFRD is Baker-Just not addressed not addressed correlation is used, it should be A-8

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets Closure: FFRD Closure: FFRD demonstrated that it should be should be bounds the coated addressed in LOCA addressed in LOCA cladding oxidation evaluation evaluation kinetics.

methodologies. If methodologies. If Note: Coated burst and thus burst and thus cladding may have FFRD is expected to FFRD is expected to an impact on occur, technical occur, technical thermal-hydraulics, justification for justification for e.g., changes in burnup threshold for burnup threshold for wettability and which FFRD is to be which FFRD is to be hydraulic diameter D

considered is needed, as well as a considered is needed, as well as a can affect the critical heat technical technical flux/critical power justification for when justification for when correlation.

the effect of the effect of Although Thermal-fragmentation fragmentation hydraulic impact of induced FGR is to be considered. The R induced FGR is to be considered. The coated cladding is expected to be limiting condition for limiting condition for minimal, this rupture with rupture with should be justified fragmentation fragmentation to confirm the should be analyzed should be analyzed continued as well. Additionally, as well. Additionally, applicability of the impact of fuel the impact of fuel thermal-hydraulic particle transport particle transport models.

and deposition on and deposition on AF coolability and coolability and criticality should be criticality should be examined, including examined, including addressing potential addressing potential sump blockage sump blockage caused by fuel particles in the caused by fuel particles in the T

coolant. coolant.

A-9

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets 10 CFR 51.21 Fully applicable Fully applicable Fully applicable Environmental CATEXs are for categories of actions whose potential for significant Note: Due to plant Note: Due to plant Assessment (EA) vs environmental impacts are so minimal that any consideration or changes and changes and 51.22 Categorical documentation of environmental impacts are not needed. The unanalyzed unanalyzed Exclusion (CATEX) changes to LWR fuel for the conditions in these three columns are environmental environmental above what has been previously analyzed for environmental impacts impacts (i.e., impacts (i.e.,

(NMSS) (i.e., 10 CFR 51.52, Environmental effects of transportation of fuel effluent releases, effluent releases, and waste - Table S-4, see below). accidents, and accidents, and It is premature to decide now to apply a CATEX due to the range of transportation of transportation of different ATF technologies and our uncertainty about what the fuel and waste) as fuel and waste) as industry will submit. Given this situation and to reduce litigative risk, a result of a result of 12 D

recommendation is to perform an EA for the first licensing action of a given type of ATF design and then use this EA as a basis for future increased enrichment and increased enrichment and similar actions (e.g., CATEX). higher burnup higher burnup levels, it is levels, it is expected that an expected that an EA should be EA should be R performed (NRC and/or industry) in performed (NRC and/or industry) in the first LAR the first LAR application for this application for this ATF type. ATF type.

10 CFR 51.51, Fully applicable Uranium fuel cycle Several aspects of the uranium fuel cycle are expected to remain unchanged from current processes (e.g., uranium environmental data recovery and conversion).

- Table S-3 Note: Prior to the submittal of an ATF LAR from a nuclear power plant licensee, the appropriate changes to the fuel cycle facilities will have to be in place with appropriate NRC approval. Examples include changes to the National AF Enrichment Facilitys license to enrich to the levels specified by ATF fabricators/vendors and whether existing fuel (NMSS) fabricators can manufacture the fuel assemblies under their existing license or need appropriate LARs approved by 13 the NRC. Thus, at the time of an ATF LAR from a nuclear power plant licensee, these associated fuel cycle impacts will be known and that prior NEPA analysis can be incorporated by reference into the LAR NEPA review.

Note: an evaluation of whether the spent ATF could be covered by the Continued Storage GEIS (NUREG-2157 T

[ML14196A105 and ML14196A107]) and 10 CFR 51.23 would need to be assessed at the time of the ATF LAR.

This assessment of spent ATF storage would involve whether the spent ATF has the same or very similar external impacts as the LWR spent fuel analyzed in the Continued Storage GEIS. The staff might be able to perform a preliminary environmental study based on the certificate of compliance applications expected in order to have relevant storage casks pre-approved for the storage of spent ATFs.

A-10

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets 10 CFR 51.52, Fully applicable Environmental Note: The proposed enrichment and burnup levels are beyond the conditions specified in 10 CFR 51.52(a) and effects of analyzed in the License Renewal GEIS (NUREG-1437 Revision 1). The staff would need to assess the impacts by transportation of fuel conducting a full description and detailed analysis of the environmental effects of transportation of fuel and waste to and waste - Table and from the reactor, including values for the conditions of transport and for the environmental risks from accidents in S-4 transport (see 10 CFR 51.52(b)).

14 Note: NUREG/CR-6703 (ML010310298) did attempt to analyze burnup levels greater than 62 GWd/MTU but found (NMSS) there was too much uncertainty in changes in the gap-release fraction associated with increasing fuel burnup. This study recommends that this be re-evaluated as the methods for assessing fission gas releases are validated with data for higher burnups (see page 52 of NUREG/CR-6703). If resources are available, the staff could perform an analysis of the transportation impacts based on aspects of NUREG/CR-6703 for burnup levels up to 80 GWd/MTU if 10 CFR 70.24 D

appropriate gap-release fractions and subsequent transportation package release fractions are available for use.

Fully applicable Fully applicable Fully applicable Fully applicable Fully applicable Criticality Accident No data gaps No data gaps Note: This No data gaps No data gaps Requirements regulation represents an 15 R alternative to 50.68: licensees can install criticality monitoring systems rather than meeting the requirements set forth in 50.68(b)

No data gaps NUREG-0630 Not fully applicable Not fully applicable Fully applicable Not fully applicable Fully applicable Cladding Swelling Reason: NUREG- Reason: NUREG- No data gaps Reason: Cladding No data gaps and Rupture Models 0630 models are 0630 models are swelling and burst AF for LOCA Analysis hot-rod models and hot-rod models and data presented is thus do not consider thus do not consider from bare zircaloy interactions interactions cladding, so should between rods. between rods. not be used if the 16 Interactions between rods affect Interactions between rods affect T benefits of coated cladding are to be swelling and rupture swelling and rupture realized.

behavior, which will behavior, which will Closure: As stated impact the amount impact the amount in coated cladding of fragmented fuel of fragmented fuel ISG that may disperse, that may disperse, (ML19343A121), if A-11

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets so should not be so should not be NUREG-0630 is neglected. neglected. used, it would be Closure: Interactions Closure: Interactions useful to show that between rods should between rods should data bounds the be considered for be considered for performance of the swelling and rupture swelling and rupture coated cladding, or modelling. modelling. if new burst stress Reason: HBU rod Reason: HBU rod and ballooning internal pressures internal pressures strain limits are may exceed the rod may exceed the rod proposed, a internal pressures of internal pressures of significant body of D

the data provided in NUREG-0630 the data provided in NUREG-0630 data would be useful to Closure: If the Closure: If the demonstrate that NUREG-0630 data is NUREG-0630 data is the degree of desired to be used, it desired to be used, it swelling will not be should be shown that should be shown that underestimated.

HBU rod internal pressures are R HBU rod internal pressures are Framework /

approach bounded by the data bounded by the data described for provided in NUREG- provided in NUREG- modeling swelling 0630. 0630. and rupture remains fully applicable.

NUREG-0800 SRP Not fully applicable Not fully applicable Not fully applicable Not fully applicable Not fully Chapter 4.2 Fuel Reason: Interim RIA Reason: Interim RIA Reason: Interim Note: Coated applicable System Design guidance provided guidance provided RIA guidance in cladding interim Reason: Interim AF in Appendix B does in Appendix B does Appendix B does staff guidance RIA guidance in not match the most not match the most not match the (ISG) Appendix B does recent guidance recent guidance current RIA (ML19343A121) not match the given in RG 1.236. given in RG 1.236. guidance in RG created to current RIA 17 Closure: Appendix B Closure: Appendix 1.236. RG 1.236 is supplement SRP guidance in RG should be updated or removed, and B should be updated or T

also not applicable to fuel enriched to Section 4.2 in coated cladding 1.236. RG 1.236 is also not readers should be removed, and greater than 5.0 reviews. applicable to directed to RG readers should be wt.%. Reason: Interim doped fuel.

1.236. directed to RG RIA guidance in 1.236. Note that Appendix B does A-12

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets Priority: Low (this is RG 1.236 is not fully Closure: See not match the Closure: See administrative in applicable to 75 discussion on RG current RIA discussion on RG nature as RG 1.236 GWd/MTU. 1.236 guidance in RG 1.236 has been published Priority: Low Note: Increased 1.236. Note that Reason: Impact of to address RIA Reason: FFRD not enrichment will RG 1.236 is also additives on fuel guidance up to 68 thoroughly promote higher rod not applicable to performance has GWd/MTU) addressed. worth and peaking coated cladding. not been Reason: FFRD not Closure: Potential factors and thus Closure: See extensively thoroughly addition of vendor fuel enthalpy rise discussion on RG quantified.

addressed. requirements for during RIAs. 1.236 and coated Closure: Data on Closure: Potential submittals if rod cladding ISG irradiated, doped D

addition of vendor requirements for burst is assumed to occur.

(ML19343A121). UO2 fuel pellets and IFBA fuel submittals where rod Priority: TBD pellets needed to burst is assumed to better understand occur. impact of additive Priority: TBD agents (e.g.,

R larger grain size, retained fission gas, grain boundary hold-up, thermal conductivity) on cladding failure thresholds, FFRD, transient FGR, and coolable AF geometry NUREG-1465 Accident Source Terms for Light Potential impacts to accident source term described above for RG 1.183 Revision 1.

18 Water Reactor Nuclear Power Plants T

A-13

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets NUREG-2121 FFRD Not fully applicable Not fully applicable Not fully applicable Fully applicable Not fully During LOCA Reason: Published Reason: Published Note: The effect of Note: Only applicable in 2012, so does not in 2012, so does not enrichment on uncoated cladding Reason: Only include recent include recent FFRD phenomena considered in tests traditional UO2 FFRD research FFRD research was not a part of described in the fuel considered in findings findings NUREG-2121 NUREG. the tests Closure: Recent Closure: Recent Note: INL Power Note: Swelling and described in the FFRD research FFRD research Burst Facility tests burst data are NUREG. Impact of findings to be findings to be included fuel needed to needed additives on fuel covered in a covered in a enriched to 9.6 to show that performance has research information research information wt%. NUREG-0630 not been D

letter (RIL)

Priority: High (near-letter (RIL)

Priority: High (near-Reason: The effect of enrichment with bounds the performance of the extensively quantified.

term) term) regard to FFRD coated cladding, or Closure: Data for Note: Halden tests Note: Halden tests during a LOCA has if new burst stress irradiated, doped described in the described in the not been well and ballooning UO2 fuel pellets and IFBA fuel NUREG include R

several tests at > 75 GWd/MTU NUREG include several tests at > 75 GWd/MTU quantified.

Closure: TBD. The strain limits are proposed, a significant body of pellets needed to better understand 19 effect of enrichment Note: Studsvick Note: Studsvick with regards to data would be impact of additive tests described in tests described in FFRD during a useful to agents (e.g., larger the NUREG include the NUREG include LOCA should be demonstrate that grain size, retained several tests at > 70 several tests at > 70 determined. the degree of fission gas, grain GWd/MTU GWd/MTU swelling will not be boundary hold-up, Note: More data is Note: More data is underestimated. thermal needed from needed from conductivity) on industry to properly industry to properly cladding failure AF address FFRD if the address FFRD if thresholds, FFRD, burst is predicted to burst is predicted to transient FGR, and occur. If burst and occur. If burst and coolable geometry.

thus FFRD is thus FFRD is expected to occur, expected to occur, technical justification for technical justification for T

burnup threshold for burnup threshold for which FFRD is to be which FFRD is to be considered is considered is needed, as well as a needed, as well as a A-14

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets technical technical justification for when justification for when the effect of the effect of fragmentation fragmentation induced FGR is to induced FGR is to be considered. be considered.

Additionally, the Additionally, the impact of fuel impact of fuel particle transport particle transport and deposition on and deposition on coolability and coolability and D

criticality should be examined, including criticality should be examined, including addressing potential addressing potential sump blockage sump blockage caused by fuel caused by fuel particles in the particles in the coolant.

R coolant.

NUREG/CR-7219 Fully applicable Fully applicable Fully applicable Not fully applicable Fully Applicable Cladding Behavior No data gaps Note: Section 3.3.2 No data gaps Reason: Data only Large population During Postulated details current included bare of fuel rods LOCA PQD results for only zirconium. Rate of beyond threshold up to 70 GWd/MTU oxidation and for cladding ID embrittlement will oxygen be different embrittlement Closure: TBD (likely Reason: BU AF not necessary) threshold for the 20 Conclusions formation of fuel-remain applicable clad bond layer Note: Single sided has not been well steam oxidation quantified in T data and subsequent doped fuel.

Closure: Hot cell mechanical data as (HC) post well as double irradiation sided integral examination (PIE) steam oxidation needed to define A-15

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets data and threshold for fuel-subsequent clad bond layer mechanical data are necessary to establish PQD limits RG 1.157 Best- Not fully applicable Not fully applicable Fully applicable Not fully applicable Not fully Estimate Reason: RG 1.157 Reason: RG 1.157 No data gaps Reason: Cathcart- applicable Calculations of is not fully is not fully Pawel correlation Reason: Section ECCS Performance applicable to the applicable to the and associated 3.2.1 on initial current BU limit of current BU limit of data is referenced stored energy in D

62 GWd/MTU. For example, thermal 62 GWd/MTU. For example, thermal as acceptable for calculating the the fuel is out of date. It also conductivity conductivity rates of energy references an degradation (TCD) degradation (TCD) release, hydrogen acceptable initial is not addressed. is not addressed. generation, and stored energy TCD occurs under TCD occurs under cladding oxidation, model. This HBU conditions.

R More information on HBU conditions.

More information on but was for a developed for bare model was developed for UO2 TCD is available in TCD is available in zircaloy cladding. and is not Information Notice Information Notice Use of the acceptable (IN) 2009-23 (IN) 2009-23 Cathcart-Pawel currently for UO2 21 (ML091550527 and (ML091550527 and correlation would or doped fuel.

ML121730336). ML121730336). not realistically Closure: It should Closure: The staff Closure: The staff model oxidation be shown that the has been aware of has been aware of kinetics. Chrome stored energy issues such as TCD issues such as TCD coated cladding is does not change AF for some time and for some time and expected to have much from a plans to update RG plans to update RG better oxidation vendors current 1.157 in the coming 1.157 in the coming performance than UO2 models, or years. years. bare zirconium new models Priority: Medium Priority: Medium cladding. should be Reason: FFRD is not addressed Reason: FFRD is not addressed T Closure: An oxidation kinetics proposed.

Note: this RG Closure: FFRD Closure: FFRD model based on provides a means should be should be chrome-coated of meeting the addressed in LOCA addressed in LOCA cladding should be 50.46 prescriptive evaluation evaluation developed. If the analytical A-16

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets methodologies. If methodologies. If benefits of the requirements; burst and thus burst and thus coating are not to those FFRD is expected to FFRD is expected to be realized and the requirements are occur, technical occur, technical Cathcart-Pawel not applicable for justification for justification for correlation is used, doped pellets due burnup threshold for burnup threshold for it should be to the wording of which FFRD is to be which FFRD is to be demonstrated that it 50.46(a)(1)(i), so considered is considered is bounds the coated this RG is only needed, as well as a needed, as well as a cladding oxidation fully applicable technical technical kinetics. pending an justification for when justification for when Note: this RG accepted D

the effect of fragmentation the effect of fragmentation provides a means of meeting the exemption to 50.46.

induced FGR is to induced FGR is to 50.46 prescriptive be considered. The be considered. The analytical limiting condition for limiting condition for requirements; rupture with rupture with those requirements fragmentation should be analyzed R fragmentation should be analyzed are not applicable for doped pellets as well. Additionally, as well. Additionally, due to the wording the impact of fuel the impact of fuel of 50.46(a)(1)(i), so particle transport particle transport this RG is only fully and deposition on and deposition on applicable pending coolability and coolability and an accepted criticality should be criticality should be exemption to examined, including examined, including 50.46.

addressing potential addressing potential AF sump blockage sump blockage caused by fuel caused by fuel particles in the particles in the coolant. coolant.

Reason: The limiting Reason: The limiting rod may not be the hot rod when rod may not be the hot rod when T

considering swelling considering swelling and rupture (see and rupture (see NUREG-0630 NUREG-0630 discussion) discussion)

A-17

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets Closure: rod to rod Closure: rod to rod interactions should interactions should be considered for be considered for swelling and rupture swelling and rupture in LOCA analyses in LOCA analyses RG 1.203 Transient Fully applicable Fully applicable Fully applicable Fully applicable Fully applicable and Accident Note: Vendors will Note: Vendors will Note: Vendors will Note: 50.46 Note: 50.46 Analysis Methods need to validate need to validate need to validate requirements are requirements are their evaluation their evaluation their evaluation discussed, so this discussed, so this models to higher models to higher models to higher RG is only fully RG is only fully BU.

D BU. enrichments applicable pending an accepted applicable pending an exemption to accepted 50.46. See exemption to 22 discussion on 50.46. See 50.46 for more discussion on R details.

Note: Vendors will 50.46 for more details.

need to update and Note: Vendors will validate their need to update evaluation models and validate their to consider coated evaluation models cladding to consider doped fuel RG 1.240 Fresh and Not fully Applicable Not fully applicable Not fully applicable Fully applicable Not fully Spent Fuel Pool Reason: Cites use Reason: Cites use Reason: Mentions No data gaps applicable AF Criticality Analysis of gap release of gap release gap release Reason: Mentions fractions from RG fractions from RG fractions from RG gap release NEI 12-16, Rev. 4 1.183 and PNNL- 1.183 and PNNL- 1.183 Rev. 0, fractions from RG 18212 Rev 1. RG 18212 Rev 1. RG which is not fully 1.183 Rev. 0, 23 1.183 Rev 0 is only 1.183 Rev 0 is only applicable. Rev. 1 which is not fully applicable up to 62 GWd/MTU and applicable up to 62 GWd/MTU and T

of that document is not fully applicable, applicable. Rev. 1 of that document PNNL-18212 Rev 1 PNNL-18212 Rev 1 but the analytical is not fully is only applicable up is only applicable up procedure remains applicable, but the to 65 GWd/MTU. to 65 GWd/MTU. applicable. analytical procedure A-18

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets Closure: Will be fully Closure: Will be fully Closure: Will be remains applicable upon the applicable upon the fully applicable applicable.

publication of RG publication of RG upon the Closure: RG 1.183 1.183 Rev 1, which 1.183 Rev 1, which publication of RG Rev 1, will provide will provide tables will provide an 1.183 Rev 1, which an analytical for gap release analytical procedure will provide an procedure for fractions for calculating gap analytical calculating gap release fractions procedure for release fractions that is applicable. calculating gap that is applicable.

release fractions Note: Section 9.3 that is applicable. of NEI 12-16 Rev.

D Note: Criticality codes must be 4 describes how to approach new validated with fuel designs.

experiments that Note: If dopant cover the increases density, applicable R enrichment range Note: Criticality higher density fuel may lead to more 235U in the spent analyses will need fuel pool to be updated to Note: Experiments show adherence to for validation of the k-effective criticality codes regulatory limits. may be necessary.

Note: RG 1.240 Section C AF paragraph o states that for new fuel designs, justification for continued use of T the assumptions presented in NEI 12-16 Rev 4 may be necessary.

A-19

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets NUREG-0800 (SRP Fully applicable Fully applicable Fully applicable Fully applicable Fully applicable 9.1.1) Criticality No data gaps No data gaps Note: Compliance No data gaps Note: Experiments Safety of Fresh and with 10 CFR 50.68 for validation of Spent Fuel Storage is a part of the criticality codes and Handling stated review may be procedures. necessary.

24 Note: Criticality analyses will need to be updated to show adherence to the k-effective NUREG-0800 (SRP D

Fully applicable Fully applicable regulatory limits.

Fully applicable Fully applicable Fully applicable 9.1.2) New and No data gaps No data gaps Note: Compliance No data gaps Note: Higher Spent Fuel Storage with 10 CFR 50.68 density fuel may is a part of the lead to more 235U 25 R stated review procedures.

in the spent fuel pool; experiments for validation of criticality codes may be necessary.

NUREG-1520 (Fuel Not applicable Not applicable Fully applicable Fully applicable Fully applicable Cycle SRP) - NMSS Reason: HBU is not Reason: HBU is not No data gaps No data gaps No data gaps applicable to the applicable to the 26 fuel fabrication. fuel fabrication.

Closure: No closure Closure: No closure AF necessary necessary NUREG-1065 Not applicable Not applicable Fully applicable Fully applicable Fully applicable Material Control and Reason: HBU is not Reason: HBU is not No data gaps No data gaps No data gaps Accounting (MC&A) applicable to the applicable to the 27 for LEU fuel fabrication fuel fabrication.

Closure: No closure fuel fabrication.

Closure: No closure T

necessary necessary.

NUREG/CR-5734 Not applicable Not applicable Fully applicable Fully applicable Fully applicable 28 MC&A for No data gaps No data gaps No data gaps enrichment facilities A-20

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets Reason: HBU is not Reason: HBU is not applicable to the applicable to the fuel enrichment. fuel fabrication.

Closure: No closure Closure: No closure necessary. necessary.

NUREG-2214, Not fully applicable Not fully applicable Not fully applicable Not fully Managing Aging Reason: The evaluations of aging-related Reason: Increased Reason: The applicable Processes in degradation of spent fuel cladding need to be use of burnable evaluations of Reason: Doped Storage (MAPS) extended to HBU. HBU may influence which absorbers may aging-related fuel pellets may Report - NMSS aging mechanisms are credible during affect cladding degradation of affect cladding extended storage and may warrant unique hoop stresses and spent fuel cladding hoop stresses (via D

recommended preventive actions (e.g., fuel drying criteria) and other aging management the associated aging-related do not consider the potential effects of pellet-clad interactions or approaches. phenomena. Cr coating. fission gas Closure: Fuel performance modeling and Closure: Fuel Closure: release) and the characterization of irradiated cladding with performance Characterization of associated aging-29 R

higher BU (e.g., mechanical testing, microstructure characterization) to assess credible aging mechanisms.

modeling and characterization of irradiated cladding irradiated Cr-coated cladding (e.g., mechanical related phenomena Closure: Fuel with increased testing, performance enrichment (e.g., microstructure modeling and mechanical testing) analysis) to assess characterization of to assess credible credible aging irradiated cladding aging mechanisms. mechanisms, such with doped pellets as hydrogen (e.g., mechanical effects, thermal testing) to assess creep, and credible aging AF corrosion. mechanisms.

NUREG-2215, Not fully applicable Not fully applicable Under review Under review Standard Review Reason: Guidance provides is limited to Reason: Guidance Note: Guidance Note: Staff is Plan for Spent Fuel burnups up 60 GWd/MTU. is limited to provides evaluating the Dry Storage - NMSS Closure: TBD enrichments up to information on Zr need to address 30 Note: Shielding discussion will need to consider high burnups and fuel composition 5%.

T Closure: TBD alloy cladding. No discussion of potential validation variations and to account for increase source term. Note: Shielding unique effect on fuel Literature reviews and research will provide discussion will need considerations for density due to fuel information on this technical issue. to consider higher Cr coated on dopants.

enrichments to cladding A-21

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets Note: Criticality discussion will need to account for performance. Staff Note: Guidance consider higher burnups as well as validation increase burnable will assess this provides and address bounding profiles for higher absorber use and impact when lead information on Zr burnup fuels. Literature reviews and impact on source test assemblys alloy cladding. No research will provide information on this term. Literature data becomes discussion of technical issue. reviews and available. Applicant unique Note: Materials evaluation will need to research will could also provide considerations for consider higher burnups effect on cladding provide information this information. fuel dopants on performance. Staff will assess this impact on this technical fuel performance.

when lead test assemblys data becomes issue. Staff will assess available. Note: Criticality this impact when D discussion will need to consider higher lead test assemblys data enrichment as well becomes as validation and available.

address bounding Applicant could profiles for higher also provide this R enrichment fuels .

Literature reviews information.

and research will provide information on this technical issue.

Note: Materials discussion will need to consider if an increase in AF burnable absorber use may affect cladding hoop stress and, consequently, the T

recommended fuel drying criteria.

Applicant could also provide information to A-22

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets support the evaluation.

NUREG-2216, Not fully applicable Not fully applicable Under review Under review Standard Review Reason: Guidance provided is limited to Reason: Guidance Note: Guidance Note: Staff is Plan for burnups up 60 GWd/MTU. is limited to provides evaluating the Transportation Closure: TBD enrichments up to information on Zr need to address Packages for Spent Note: Shielding discussion will need to 5%. alloy cladding. No potential validation Fuel and consider high burnups and fuel composition Closure: TBD discussion of variations and Radioactive Material to account for increase source term. Note: Shielding unique effect on fuel Literature reviews and research will provide discussion will need considerations for density due to fuel D

information on this technical issue.

Note: Criticality discussion will need to to higher enrichments to Cr coated on cladding dopants.

Note: Guidance consider higher burnups as well as validation account for performance. Staff provides and address bounding profiles for higher increase burnable will assess this information on Zr burnup fuels. Literature reviews and absorber use and impact when lead alloy cladding. No test assemblys technical issue.

R research will provide information on this impact on source term. Literature reviews and data becomes available. Applicant discussion of unique considerations for Note: Materials evaluation will need to consider higher burnups effect on cladding research will could also provide fuel dopants on 31 performance. Staff will assess this impact provide information this information. fuel performance.

when lead test assemblys data becomes on this technical Staff will assess available. issue. this impact when Note: Criticality lead test discussion will need assemblys data to consider higher becomes enrichments as well available.

AF as validation and Applicant could additional isotopic also provide this depletion, and information.

bounding profiles.

Literature reviews T

and research will provide information on this technical issue.

Note: Materials discussion will need A-23

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets to consider if an increase in burnable absorber use may affect cladding hoop stress and, consequently, the recommended fuel drying criteria NUREG-2224, Dry Not fully applicable Not fully applicable Not fully applicable Not fully Storage and Transportation of D

Reason: The evaluations of fuel cladding performance and recommended licensing Reason: Increased use of burnable Reason: The evaluations of fuel applicable Reason: Doped High Burnup approaches need to be extended to higher absorbers may cladding fuel pellets may BU. Increased BU may influence cladding affect cladding performance do not affect cladding internal pressure, mechanical properties, and hoop stresses and consider the hoop stresses (via the credible aging mechanisms during the associated potential effects of pellet-clad R

extended storage. Increased BU may also warrant revised recommended fuel drying cladding behavior.

Closure: Fuel Cr coating (e.g.,

cladding oxidation, interactions or fission gas practices to maximize cladding performance. performance hydrogen pickup). release) and the Closure: Fuel performance modeling and modeling and Revised fuel drying associated characterization of irradiated cladding with characterization of criteria to consider cladding higher BU (e.g., mechanical testing, irradiated cladding effects of reduced performance 32 microstructure characterization) with increased hydrogen pickup in Closure: Fuel enrichment (e.g., the reactor may be performance mechanical testing) warranted. modeling and Closure: characterization of AF Characterization of irradiated cladding irradiated Cr- with doped pellets coated cladding (e.g., mechanical (e.g., mechanical testing) testing, T microstructure analysis)

A-24

235 Regulatory Guide Burnup to Burnup to U Enrichment Chrome-coated Doped UO2 Fuel or Regulation 68 GWd/MTU 75 GWd/MTU beyond 5.0 wt% Zirconium Cladding Pellets RG 3.48 Standard Fully applicable Fully applicable Fully applicable Fully applicable Fully applicable Format and Content No data gaps No data gaps No data gaps No data gaps No data gaps 33 for the Safety Analysis Report for An ISFSI (NMSS)

RG 7.9, Standard Fully applicable Fully applicable Fully applicable Fully applicable Fully applicable Format and Content No data gaps No data gaps No data gaps No data gaps No data gaps of Part 71 Applications for 34 Approval of Packages for Radioactive Material (NMSS)

D RG 3.71, Nuclear Not applicable Not applicable Fully applicable Fully applicable Fully applicable Criticality Safety Reason: HBU is not Reason: HBU is not No data gaps No data gaps No data gaps Standards for applicable to the applicable to the 35 Nuclear Materials Outside Reactor Cores (NMSS) fabrication.

R fuel enrichment or Closure: No closure fuel enrichment or fabrication.

Closure: No closure necessary necessary RG 3.67/ Not applicable Not applicable Fully applicable Fully applicable Fully applicable Emergency Reason: HBU is not Reason: HBU is not No data gaps No data gaps No data gaps Preparedness applicable to the applicable to the 36 fuel enrichment or fuel enrichment or fabrication. fabrication.

Closure: No closure Closure: No closure necessary necessary AF T

A-25

APPENDIX B: LICENSING PATHWAYS The U.S. Nuclear Regulatory Commission (NRC) staff has developed licensing pathways to depict the remaining informational needs or tasks that should be completed in order to efficiently review accident-tolerant fuel (ATF) topical reports and plant-specific license amendment requests.

These two pathways, shown in Figures B.1-1 and B.1-2, are a simple depiction of the closure items identified in the Regulatory Framework Applicability Assessment table in Appendix A for higher burnup fuel.

Following the same color scheme from the Regulatory Framework Applicability Assessment table, green colored boxes are items to be addressed by NRC staff and blue colored boxes are items to be addressed by a fuel vendor or a licensee. This is also illustrated by items above the needs).

T horizontal line (NRC actions) and below the horizontal line (fuel vendor or licensee information Boxes with hashed shading are related to the environmental review. Boxes that are linked by dashed arrows indicate a relationshipif not addressed by the NRC, then it should be R

evaluated by the fuel vendor or considered by the licensee during the review of the license amendment request.

AF Items to the left of the vertical line are actions or information needs that ideally should be completed prior to the submittal of plant-specific license amendment requests (LARs). This will ensure an efficient review of LARs. If such items are not completed prior to the submittal of a LAR, then schedule risk may increase.

The lone blue colored box with a dashed border is specific to licensees that have not yet adopted an alternate source term of non-loss-of-coolant accidents.

Lastly, the dashed border around the Advisory Committee on Reactor Safeguards (ACRS)

Review box on the plant-specific LAR review pathway indicates the possibility of an ACRS review.

D Pathways for other ATF concepts are under development and will be added to this appendix in a future revision.

B-1

B.1: Higher Burnup Licensing Pathways D

R AF T

Figure B.1-1 Higher Burnup Topical Report Reviews B-1

D R

AF T

Figure B.1-2 Higher Burnup Plant-Specific LAR Reviews B-2

APPENDIX C: CHANGE HISTORY ITEM LOCATION REVISION DESCRIPTION 1 Page 5, Section 2, 1.1 ATF Steering Committee figure updated to Figure 2.1 reflect Office merger related changes.

2 Page 7, Section 3, 1.1 ATF Milestone Schedule table updated.

Table 3.1 3 Page 13, Section 1.1 Section updated to reflect completed PIRT 3.4.3 actions.

4 Page 25, Section 7.2 1.1 LTA section updated to identify agency position letter.

5 Page 25, Section 7.4, 1.1 Basic edits made to the table.

Table 7.4 6 Appendix A 1.1 New Appendix A added: Fuel Burnup and Enrichment Extension Preparation Strategy.

7 8

Appendix B Appendix C 1.1 1.1 T

Minor edits also made throughout document to capture the Appendix referencing.

Previous Appendix A moved to Appendix B.

Minor editorial changes throughout.

New Appendix C added to capture document 9

10 RAppendix A AF Appendix B 1.2 1.2 change history.

Previous Appendix A was re-incorporated into the main body of the project plan and replaced with the Regulatory Framework Applicably Analysis as a new Appendix A for in-reactor and fuel cycle, transportation, and storage.

Replaced Appendix B in its entirety with licensing pathway diagrams.

D C-1