ML24345A133

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NRC Presentation PWROG Rmc Meeting December 11 2024-Rev.2
ML24345A133
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Issue date: 12/11/2024
From: Meena Khanna
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NRC PRESENTATION PWROG RMC MEETING December 11, 2024 Meena Khanna, Acting Director Division of Risk Assessment Office of Nuclear Reactor Regulation

Agenda

  • Risk-Informed Materials Assessment Status - David Gennardo
  • Group for Risk Evaluation and Assessment Tools Review Status - John Hanna
  • International Engagements: The Journey to Being an Independent, Modern Risk-Informed Regulator - Sunil Weerakkody 2

Opening Remarks

  • ADVANCE Act
  • NRR Risk-Informed Initiatives
  • Increased Enrichment Rulemaking
  • 50.69 Public Workshop
  • PRA Configuration Control 3

High-Level Overview of the ADVANCE Act

  • Enhance initiatives to achieve efficient, timely, and predictable license application reviews
  • An expedited procedure for reviewing qualifying new reactor license applications
  • Develop a regulatory framework for fusion technology
  • Develop strategies and guidance for microreactors
  • NRC Presentation on Advance Act ML24285A217 Section 505 Section 507 Provide licensing efficiencies on review of applications Improve the oversight and inspection program Project Nuclear License Efficiencies Project Oversight and Inspection Programs Internal deliverable due July 2025 Due to Commission June 2025 Due to Congress July 2025 For NRCs public information site for ADVANCE Act updates 4

NRR Risk-Informed Initiatives Licensing Efficiency and Processes (LEAP)

Power Uprates (PUR)

Reactor Restart Efforts Expanding the use of RIDM/Risk-Informed Initiatives RIDM 2.0 Workshops and training activities to enhance the use of RIDM 50.69 KM/KT Workshop LIC-206 Tiger Team to grade licensing reviews and leverage risk tools and insights RIPE/Expanding RIPE with Qualitative Criteria Subsequent License Renewal Digital I&C Licensing Guidance 5

NRR Risk-Informed Near-Term Actions NRR Risk-Informed Near-Term Actions Increased Enrichment Rulemaking Increased Enrichment Rulemaking 50.69 Public Workshop 50.69 Public Workshop PRA Configuration Control Performance Based Review PRA Configuration Control Performance Based Review 6

Increased Enrichment Rulemaking

  • Control Room Dose Criteria
  • Purpose is to enable performance-based evaluation using traditional deterministic radiological consequence analysis within risk-informed boundaries
  • Approach by leveraging IE RM proposal to amend the control room design criteria to a higher numerical value but still providing for safe performance criteria, while considering plant-specific risk information (ML23032A504).
  • The IE RM, including DG-1425 (Draft RG 1.183, Rev. 2), will be presented to ACRS Subcommittee on December 17 and 18; and the ACRS SC meeting on December 19 will be focused on DG-1425. This information will be presented to the full ACRS Committee in February 2025.
  • 50.46a Change Process
  • The purpose of the risk-informed evaluation is to ensure changes enabled under 10 CFR 50.46a are limited to very small changes in risk, as directed by SRM-SECY-2007-0082.
  • The risk-informed evaluations use the risk-informed framework already defined in RG 1.200 for determining PRA acceptability and in RG 1.174 for evaluating the impact of changes.
  • The risk-informed evaluation process allows for some enabled changes that have less than a minimal impact on risk, to be made without prior NRC approval after the licensee's adoption of 50.46a is reviewed and approved.
  • A draft Regulatory Guide (DG), DG-1426, outlining the risk-informed evaluation process was published in November (ML24319A118) in support of the December ACRS SC meetings on the IE RM and Draft RG.
  • The IE RM, including DG-1426, will be presented to ACRS Subcommittee on December 17 and 18. This information will be presented to the full ACRS Committee in February 2025.

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50.69 Public Workshop

  • Audience: New NRR and Industry Staff and those staff who will benefit from this knowledge to support risk-informed reviews
  • Agenda:
  • Overview of 50.69
  • Licensing
  • Industry licensing experience
  • NRC review experience
  • Implementation and Categorization process
  • Oversight
  • Industry oversight experience
  • NRC oversight experience
  • Workshop is scheduled for February 11th PRA Configuration Control
  • Annual Performance-Based Review - Feb 2025
  • Evaluate samples, screenings, and more than minor determination.
  • Evaluate application based on adopted risk-informed initiatives.
  • Update Operating Experience Smart Sample, as needed
  • To date, we believe updates are unlikely given the limited sample experience 8

Q&A 9

Digital I&C Update Steve Alferink

Digital I&C Update

  • Continued engagement with industrys digital I&C community during the development of implementing guidance
  • Proceeding with efforts to quantify values for software common cause failures (CCFs)
  • Will enhance the acceptability of PRA in future risk-informed initiatives
  • Ongoing challenges with risk informing digital I&C
  • Ensuring the standards used to model I&C systems in PRA have the capability to capture and model inter-and intra-I&C system dependencies accurately
  • Ensuring the guidance used to identify surrogate events is effective 11

Reactor Accident Analysis Modernization (RAAM)

Sunil Weerakkody

What is the RAAM Working Group?

  • The RAAM Working Group is a team of seven senior technical experts and reviewers from multiple offices and divisions
  • Members have extensive background in either accident analysis or risk analysis
  • The RAAM Working Group was formed at the request of the NRR Executive Team to look for improvements in licensing related to reactor accident analysis 13

Goals of the RAAM Working Group

  • Review NUREG-0800 Ch. 15 methods and propose ways to modernize the approach
  • Use a holistic approach
  • Risk inform where possible
  • Use insights from ongoing reviews and related efforts
  • Focus on both operating and new light water reactors
  • Produce a report for the NRR Executive Team summarizing the RAAM WGs Conclusions
  • Ideas that could be further investigated
  • Options for implementation
  • Level of interest from both operating reactors and new applicants
  • Final recommendation for each idea 14

RAAM WG Identified Focus Areas

  • Non-Safety-Related Systems, Structures and Components (SCCs)
  • Loss of Coolant Accidents
  • Single Failure Criteria
  • Environmental Qualification
  • Design Basis Accidents
  • Licensing Modernization Project (LMP) Applications 15

The RAAM WG developed potential ideas for enhancements and evaluated potential options In several cases, significant past work has been done to develop potential enhancements - this past work can be leveraged as appropriate The WG considered several attributes Resource Impact Potential benefit to operating LWRs Potential benefit to new LWR applicant U.S. NRC, Draft Reactor Accident Analysis Modernization Report, dated July 31, 2024, Agencywide Documents and Access Management Systems (ADAMS) Accession No. ML24213A123.

U.S. NRC Presentation, NRC Presentation 14 Public Meeting to Discuss LWR Reactor, Accident Analysis Modernization (RAAM) Efforts, dated August 14, 2024, ML24220A292.

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17 Item Report Section Resource Impact Potential Benefit RAAM WG Comment Operating Reactors New Reactors Redefine Acceptable Fuel Design Limits (SARRDLs /

SAFDLs) 2.1 Risk-Informed Guidance for Crediting Non-Safety-Related SSCs 2.2 RAAM WG Conclusions (**undergoing revisions to address public and management comments)

18 Item Report Section Resource Impact Potential Benefit RAAM WG Comment Operating Reactors New Reactors Use of an Alternate Criteria to 95/95 for LOCA 2.3 Redefine Large Break LOCA to Beyond Design Basis Event 2.4 Reconsideration of LOCA Break Locations 2.5 RAAM WG Conclusions (**undergoing revisions to address public and management comments)

19 Item Report Section Resource Impact Potential Benefit RAAM WG Comment Operating Reactors New Reactors Risk-inform Single Failure Criteria 2.6 Define Single Passive Failures for Fluid Systems 2.7 RAAM WG Conclusions (**undergoing revisions to address public and management comments)

20 Item Report Section Resource Impact Potential Benefit RAAM WG Comment Operating Reactors New Reactors Risk-Inform EQ Radiological Requirements 2.8 Increase the Coherence and Consistency of DBA Radiological Consequence Analysis 2.9 RAAM WG Conclusions (**undergoing revisions to address public and management comments)

21 Item Report Section Resource Impact Potential Benefit RAAM WG Comment Operating Reactors New Reactors Use of LMP Results to Focus Staff Reviews 2.10 Use of Event Sequence Frequencies to Risk-Inform Design Basis Event Categorization 2.11 RAAM WG Conclusions (**undergoing revisions to address public and management comments)

Next Steps

  • Finalize RAAM Working Group report and publish it after addressing comments from the public and the NRC senior management.
  • Implement a subset of actions based on directions from the NRC senior management.

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Discussion and Q&A 23

Risk-Informed Materials Assessment (RIMA)

David Gennardo

RIMA Guidance Background

  • Focus is on LIC-206 Box 7 type applications and reviews with non-integrated teams (i.e., NRC materials engineers review only).
  • Uses the same terminology as for risk-informed decision-making (or integrated decision-making) but does not require the use of RG 1.174.
  • Intent is to provide clearer/broader guidance in the language of materials engineers.
  • Goal is for the guidance to enable high quality submittals and more efficient staff review.
  • The guidance is not considered to be a change in NRC position but will allow for a more graded approach to reviews.

LIC-206, Fig. 1 25

RIMA Guidance Background (continued)

  • Concepts like defense-in-depth, safety margins (e.g., using approved codes and standards), and accounting for uncertainties, have always been considered on some level as part of traditional (a.k.a. deterministic) reviews.
  • Typically, materials engineering reviews help establish the level of assurance required for a system, structure, or component based on its safety significance. (These reviews would not be expected to establish the defense-in-depth in the design of system or the acceptance criteria in the accident analyses.)
  • RIMA guidance will further clarify the relationship between materials engineering topics and defense-in-depth considerations to better address questions like: Is treatment of subject systems commensurate with defense-in-depth functions of subject systems?
  • RIMA guidance will further clarify the relationship between materials engineering topics and safety margin considerations to better address questions like: Are safety margins sufficient, in concert with other principles of integrated decision-making, to address uncertainties?

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RIMA Guidance Background (continued)

  • The NRC position is that some level of performance monitoring has always been required (depending on the safety significance of the system, structure, or component), or assumed, even for traditional reviews. However, there are several aspects that should be considered when determining the adequacy of performance monitoring.
  • RIMA guidance will help address questions like: How much monitoring? What kind of monitoring? How often? Are there triggers for more or less monitoring within the monitoring program?
  • RIMA guidance will also provide clarification and discussion of risk insights derived from qualitative or non-PRA modeling (e.g., the use of insights from probabilistic analyses, like probabilistic fracture mechanics (PFM) analyses). (See RG 1.245 for more guidance on PFM.) Like consideration of defense-in-depth, these insights can help determine the necessary level of performance monitoring, safety margins, etc.

Note: In this context, risk insights do not include change in core damage frequency or large early release frequency or other risk importance measures required as part of a risk-informed submittal (e.g., adoption of 50.69 or TSTF-505).

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RIMA Guidance Status

  • Guidance is still in development and has not yet been submitted as part of a formal process (e.g., regulatory guide process).

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Discussion and Q&A 29

Group for Risk Evaluation and Assessment Tools Review (GREATR) Status John Hanna

Group for Risk Evaluation and Assessment Tools Review (GREATR)

  • Public meeting held on July 17, 2024 (ML24185A244) to discuss completed updates and propose draft future changes:
  • Enhanced Realism for Offsite/Onsite Power Recovery Probabilities
  • Improved Clarity & Consistency on Initiating Event Assessments
  • Update to the Risk Assessment of Operational Events Handbook, Volume 1, Internal Events
  • With regard to Section 5, "Common Cause," interest was shown during a public meeting for additional public interaction on proposed model changes for common-cause failures. The meeting was held October 30, 2024.
  • Adjustments will recognize 1) Component Specific CCF modeling, 2) Causal Alpha factor method, and 3) cross-unit CCF
  • Risk Assessment of Operational Events Handbook (RASP) changes will be available in draft and will be shared during the January 2025, ROP Bimonthly meeting.

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Discussion and Q&A 32

International Engagements: The Journey to Being an Independent, Modern Risk-Informed Regulator**

Sunil Weerakkody

34 OBJECTIVES OF THE PWROG/BWROG RISK-INFORMED INDUSTRY SAFETY IMPROVEMENT ROADMAP Assist the Japanese Membership with an actionable plan for use of Risk Informed Decision-making capability via explanation of the process used in the US industry.

Explain how the US Risk-Informed applications were developed in partnership between the United States Nuclear Regulatory Commission (NRC) and US utilities.

Provide examples of technical adequacy requirements that allow for the use of safety enhancing risk informed decision making.

Key Messages

  • Since its inception in 1974, the US NRC has used risk-informed insights to significantly reduce risks associated with facilities which it regulates.
  • US NRC is equipped with an infrastructure to achieve its safety objectives efficiently, using risk-informed approaches as an independent regulator while maintaining openness with the regulated community.
  • Since the issuance of PRA Policy in 1995, the US NRC has promulgated a number of risk-informed initiatives, by significantly leveraging industry resources if necessary, and has effectively encouraged licensees toward a more risk-informed mindset.

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OUTLINE 1.

Evolutions of the US NRCs Mission 2.

First ten years (1975 ~ 1985): Discovering unique capabilities of PRA 3.

Next ten years (1986 ~ 1995): Mandating risk-informed requirements 4.

Developing regulatory tools motivate risk-informed environment via voluntary initiatives while maintaining or improving safety 5.

Snapshot of current risk-informed programs and new horizons

6. Concluding remarks 36
1. Evolutions in the United States Nuclear Regulatory Commissions Mission
  • Formation of the US Nuclear Regulatory Commission by the US Congress (1974)
  • Accelerated Deployment of Versatile Advanced Nuclear for Clean Energy (ADVANCE) Act (2024) 37
3. Next ten years (1986 ~ 1995): Mandating risk-informed requirements and developing the infrastructure to operate as an independent, risk-informed regulator Publication of the Safety Goal Policy Statement (52 FR 30028)

(1986)

Promulgation of mandatory risk-informed Rules (e.g., 10 CFR 50.62, the ATWS Rule, 10 CFR 50.63-SBO Rule) to reduce risk.

Issuance of GL 88-20 and its supplements 38

4. Developing regulatory tools motivate risk-informed environment via voluntary initiatives while maintaining or improving safety Five Principles of Good Regulation (POGRs) that promote risk-informing and encourage soliciting stakeholder views (i.e., Independence without Isolation) (1991),

Publication of the PRA Policy Statement (60 FR 42622) (1995)

Issuance of RG 1.174 Rev. 0 (1997)

Issuance of RG 1.200 Rev. 0 (2004) 39

Snapshot of current risk-informed programs and new horizons 40 2010 2000 Revised Maintenance Rule 10 CFR 50.65(a)(4) 1980 1990 Combustible Gas Control 10 CFR 50.44 Alternative Fire Protection 10 CFR 50.48(c)

Special Treatment 10 CFR 50.69 PRA Required New Reactors 10 CFR 50.71(h);

52.47 Pressurized Thermal Shock 10 CFR 50.61a Risk-Informed Reactor Oversight Process SECY-99-007A Phased Approach To PRA Quality SRM-COMNJD-03-0002

  • Increased Fuel Enrichment Rulemaking 2024.
  • Proposed 10 CFR 53, Risk Informed, Technology-Inclusive Regulatory Framework for Advanced Reactors
  • Seismic and Flooding Reevaluations (NTTF 2.1, 2.2)
  • GSI-191
  • Integrated Review Teams
  • Risk Informed Process for Evaluations (RIPE)
  • Expanded use of Integrated Risk-Informed Decision-Making Process for Emergent Issues (LIC-504)

Risk-Informed Performance Based Regulation SECY 98-144 40

Based on the ASP indicator, the Industry safety trend continues to improve using risk-informed initiatives that enabled removing unnecessary conservatisms.

41 Industry safety trend continues to improve using risk-informed initiatives that enabled removing unnecessary conservatisms.

Industry Safety Trend Based on Nuclear Energy Institute (NEI) 20-04 Excerpt from NEI 20-04,The Nexus Between Safety and Operational Performance in the US Nuclear Industry" Since the publication of the PRA policy (1995),

which endorsed the removal of unnecessary conservatisms using PRA, the NRC has enabled the industry to implement several risk-informed initiatives (e.g., SFCP, RICT, NFPA 805, 10 CFR 50.69).

The PRA Acceptability framework (Regulatory Guides 1.174 and 1.200) has enabled the staff to grant these relaxations without affecting public confidence and safety.

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5. Concluding Remarks
  • Recognize that becoming a modern risk-informed regulator is a journey. It is a marathon, not a sprint.
  • Take on less complex risk-informed initiatives (e.g., risk-informed ISI, risk-informed ROP) first and achieve small successes throughout the journey.
  • Recognize that a nations ability to succeed in establishing a risk-informed nuclear enterprise requires a strong commitment and a conviction that risk-informing enhances public safety.
  • Form partnerships among the regulators, regulated community, and the public.
  • Acquire tools to operate as an independent regulator (e.g., policies such as PRA policy, tools such as PRA models, human capital).
  • Create mechanisms to leverage industry resources and maintain public confidence throughout the journey.

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Discussion and Q&A 44

Acronyms 45 ACRS = Advisory Committee on Reactor Safeguards ATWS = Anticipated Transient Without Scram CCF = Common Cause Failure CFR = Code of Federal Regulations DPO = Difference in Professional Opinion EPRI = Electric Power Research Institute GREATR = Group for Risk Evaluation and Assessment Tools Review IE = Increased Enrichment KM = Knowledge Management LEAP = Licensing Efficiency and Processes NRC = Nuclear Regulatory Commission NRR = Office of Nuclear Reactor Regulation NEIMA = Nuclear Energy Innovation and Modernization Act OpESS = Operating Experience Smart Sample PCC = PRA Configuration Control PRA = Probabilistic Risk Assessment PWROG = Pressurized Water Reactor Owner's Group RAAM = Reactor Accident Analysis Modernization RASP = Risk Assessment Standardization Projectperational Events Handbook RG = Regulatory Guide RICT = Risk-Informed Completion Time RIDM = Risk-Informed Decisionmaking RI-ISI = Risk-Informed Inservice Inspection RIMA = Risk-Informed Materials Assessment RIPE = Risk-Informed Process for Evaluations RIP = Risk-Informed Programs RM = Rulemaking ROP = Reactor Oversight SDP = Significance Determination Process SECY = Commission Papers SFCP = Surveillance Frequency Control Program SRM = Staff Requirements Memoranda TSTF = Technical Specifications Task Force

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