ML24339B801
| ML24339B801 | |
| Person / Time | |
|---|---|
| Issue date: | 12/05/2024 |
| From: | Sunil Weerakkody NRC/NRR/DRA |
| To: | |
| References | |
| Download: ML24339B801 (38) | |
Text
The Journey to Being an Independent, Modern, Risk-Informed Regulator Sunil D. Weerakkody, Ph.D.,
Senior Level Advisor in Probabilistic Risk Assessment Division of Risk Assessment Office of Nuclear Reactor Regulation Japan-OG-NRA-OCT-2024 1
Japan-OG-NRA-OCT-2024 2
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.
Japan-OG-NRA-OCT-2024 3
OBJECTIVES OF THE US NRC PRESENTATION Explain how the US NRC championed the development and implementation of risk-informed initiatives, by extensively leveraging industry resources when needed, to enhance public health and safety within the construct of US NRCs Principles of Good Regulations.
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.
Japan-OG-NRA-OCT-2024 4
Many regulatory actions implemented since the inception of the US NRC in 1974 were risk-informed. They have contributed, sometimes significantly, to reducing risks.
- NRCs Office of Nuclear Regulatory Research (RES) evaluates operating experience to determine safety trends using its Accident Sequence Precursor (ASP) program.
- Based on the ASP indicator, the safety of the operating fleet of reactors have continuously improved.
- NRCs steady move towards risk-informing the regulatory framework has been instrumental in focusing staff and licensee resources on issues commensurate with their safety significance.
Japan-OG-NRA-OCT-2024 5
OUTLINE 1.
Evolutions of the USNRCs Mission 2.
First ten years (1975 ~ 1985): Discovering unique capabilities of PRA 3.
Next ten years (1986 ~ 1995): Mandating risk-informed requirements 4.
Journey since (~1995): Motivating risk-informed environment via voluntary initiatives 5.
Concluding remarks Japan-OG-NRA-OCT-2024 6
- 1. Evolutions in the United States Nuclear Regulatory Commissions Mission Japan-OG-NRA-OCT-2024 7
Formation of the US Nuclear Regulatory Commission by the US Congress (1974)
- Prior to 1974, the Atomic Energy Commission (AEC) regulated and promoted post-war activities that promoted peaceful use of nuclear energy.
- By 1974, the AEC's regulatory programs had come under such strong attack that the U.S. Congress decided to abolish the Atomic Energy Commission (AEC).
- The US Congress enacted the Energy Reorganization Act of 1974.
- That act, abolished the AEC and assigned its functions to two new agencies: the Energy Research and Development of Administration and the Nuclear Regulatory Commission.
- The sole focus of the NRC was public health and safety.
- In 1977, President Jimmy Carter signed into law the Department of Energy Organization Act of 1977, which created the Department of Energy (DOE). The DOE absorbed development and administration of energy research.
- Since nuclear energy is instrumental in the USs energy independence, and national interests, the DOE and the NRC collaborate on research related activities that enable its safe use.
Japan-OG-NRA-OCT-2024 8
US Nuclear Regulatory Commission Mission: Tweaks occur but primary mission remains unchanged US NRC MISSION: The US Nuclear Regulatory Commission licenses and regulates the Nations civilian use of radioactive materials, to provide reasonable assurance of adequate protection of public health and safety, to promote the common defense and security, and to protect the environment (US NRC Strategic Plan, NUREG-1614, Volume 8).
Excerpt from the Nuclear Energy Innovation and Modernization Act (NEIMA)
(2019): For commercial advanced nuclear reactors, the NRC must (1) establish stages within the licensing process; (2) increase the use of risk-informed, performance-based licensing evaluation techniques and guidance; and (3) establish by the end of 2027 a technology-inclusive regulatory framework that encourages greater technological innovation.
Excerpt from the Accelerated Deployment of Versatile Advanced Nuclear for Clean Energy (ADVANCE) Act (2024): NRC will conduct its regulatory activities in a manner that does not unnecessarily limit (1) the civilian use of radioactive materials and deployment of nuclear energy; or (2) the benefits of civilian use of radioactive materials and nuclear energy technology to society.
Japan-OG-NRA-OCT-2024 9
- 2. First ten years (1975 ~ 1985)
Discovering unique capabilities of PRA such as the ability to enlighten the adequacy of defense-in-depth Japan-OG-NRA-OCT-2024 10
During its first ten years (1975 ~ 1985), the US NRC discovered the unique capability of PRAs to assess the adequacy of defense-in-depth (DID) and identify risk outliers.
- The Reactor Safety Study (WASH-1400) (1975) provided significant insights such as:
- TMI-2 Accident (1978) confirmed finding of the WASH-1400 Reactor Safety Study (1975).
- The Severe Accident Policy signaled NRCs unambiguous commitment to use PRAs to enhance plant safety.
Japan-OG-NRA-OCT-2024 11 Important accident sequences include Small Loss of Coolant Accidents, Transients, and Station Blackout.
Support systems, operator actions, and containment bypass are important.
Consequences of accident are significantly smaller than WASH-0740.
Insights from WASH-1400, TMI-2 accident, and various PRA studies led to the issuance of the Severe Accident Policy Statement (50 FR 32138) (1985)
New Plants Resolution of TMI requirements (50.34(f)), and certain USIs and GSIs Completion of PRAs and consideration of severe accident vulnerabilities Completion of a staff review for new designs using an approach that stresses deterministic engineering analysis and judgment complemented by PRA.
Operating Plants Plans to conduct systematic search for severe accident vulnerabilities (i.e., IPE/IPEEE under GL 88-20)
No further regulatory action to deal with severe accident issues is needed unless significant issues that could impose undue risks to the adequate protection of public safety are identified.
12 Japan-OG-NRA-OCT-2024
- 3. Next ten years (1986 ~ 1995)
Mandating risk-informed requirements and developing the infrastructure to operate as an independent, risk-informed regulator Japan-OG-NRA-OCT-2024 13
During approximately the next ten years (1986 ~ 1995), the NRC initiated various regulatory activities (promulgating rules, formulating policies, and issuing requests for information) that prompted US licensees to create PRA models and use insights derived from them to enhance plant safety.
- Publication of the Safety Goal Policy Statement (52 FR 30028) (1986) which included Qualitative Safety Goals supported by Quantitative Health Objectives (QHOs) and subsidiary risk metrics acted as catalysts to further promote development of quantitative risk assessment tools.
- Risk-Informed Rules (e.g. 10 CFR 50.62, the ATWS Rule, 10 CFR 50.63-SBO Rule) mandated risk reductions.
Japan-OG-NRA-OCT-2024 14
Safety Goal Policy Statement (52 FR 30028)
(1986)
Qualitative Safety Goals
- Individual members of the public should be provided a level of protection from the consequences of nuclear power plant operation such that individuals bear no significant additional risk to life and health.
- Societal risks to life and health from nuclear power plant operation should be comparable to or less than the risks of generating electricity by viable competing technologies and should not be a significant addition to other societal risks.
Japan-OG-NRA-OCT-2024 15
GL 88-20 and its supplement (issued beginning May 1988) requested that licensees perform an Individual Plant Examination to identify plant-specific vulnerabilities to severe accidents and report the results to the Commission.
- Prior to 1988, many licensees lacked the technical capability to conduct detailed studies until tools and methods were developed and refined to aid in analysis.
- It was observed that staff at many utility licensees did not fully understand the subtle nature of system interactions, operator actions, and their consequences.
- Performing PRAs prompted licenses to develop PRA tools, use them to identify risk outliers, and take cost-effective measures to reduce risks.
- GL 88-20 contributed to SIGNIFICANT reductions in risk at a number a plants since it prompted utilities to identify and reduce or eliminate risk-outliers.
Japan-OG-NRA-OCT-2024 16
Progress in early 1990s.
- The US NRC equipped itself to operate as an Independent Safety Regulator (without isolating itself from the industry) using the Principles of Good Regulations (POGR).
- The US NRC acknowledged the need to reduce unnecessary regulatory burdens to enable safe operation of nuclear power plants via the PRA Policy (1995).
- The US NRC created primary tools such as Regulatory Guide 1.174 and 1.200 to enable the reduction of unnecessary burdens.
Japan-OG-NRA-OCT-2024 17
The Principles of Good Regulation Independence Efficiency Openness Clarity Reliability Japan-OG-NRA-OCT-2024 18 In 1991, the Commission issued its five Principles of Good Regulation (POGRs).
to focus NRC staff on ensuring safety and security while appropriately balancing the interests of the NRC's stakeholders, including the public and licensees.
Independence:
Nothing but the highest possible standards of ethical performance and professionalism should influence regulation. However, independence does not imply isolation. All available facts and opinions must be sought openly from licensees and other interested members of the public. The many and possibly conflicting public interests involved must be considered. Final decisions must be based on objective, unbiased assessments of all information, and must be documented with reasons explicitly stated.
Japan-OG-NRA-OCT-2024 19
Independence without Isolation-An example This process is to obviate the need for a detailed NRC staff review of the licensees PRA RG 1.200 provides NRC staff position Peer Review Process to demonstrate conformance with PRA Standard PRA Standard to demonstrate conformance with staff position PRA ACCEPTABILITY 20 20 Japan-OG-NRA-OCT-2024 The NRCs endorsements of the ASME\\ANS PSA Standards are exemplary examples of how the NRC leverages industry resources to achieve its safety mission.
Efficiency The American taxpayer, the rate-paying consumer, and licensees are all entitled to the best possible management and administration of regulatory activities.
The highest technical and managerial competence is required, and must be a constant agency goal.
NRC must establish means to evaluate and continually upgrade its regulatory capabilities. Regulatory activities should be consistent with the degree of risk reduction they achieve. Where several effective alternatives are available, the option which minimizes the use of resources should be adopted.
Regulatory decisions should be made without undue delay.
Japan-OG-NRA-OCT-2024 21
LIC-504 Integrated Risk-Informed Decision Making for Emergent Issues is an exemplary example of how the US NRC adjusts regulatory response to risk significance.
Spectrum of Regulatory Options Immediate regulatory action Formal backfit analysis ( 10-4) 50.54(f) letters Bulletin Information Notice/Outreach Smart inspection samples -
No Actions Use RIDM - not numbers alone 22 Japan-OG-NRA-OCT-2024 22
Subset of NRC tools that enables the NRC to leverage industry resources to accomplish its safety mission while maintaining its independence.
Electric Power Research Institute
- NRR Office Instruction COM 204: Informal Interfacing with and Handling Documents from Owners, Groups, Vendors, Nuclear Energy Institute, Licensees, and Other External Stakeholders Management Directive (MD) 3.5: To support the Commissions intent to keep the public informed of agency activities and provide opportunities for public involvement MD 3.9: NRC Staff and Contractor Speeches, Presentations, Papers, and Journal Articles on Regulatory and Technical Subjects MD 7: Legal and Ethical Guidelines and associated mandatory training to the NRC staff Japan-OG-NRA-OCT-2024 23
PRA Policy Statement (60 FR 42622)
Publication of the PRA Policy (1995) was a significant impetus for numerous other risk-informed voluntary options that followed.
The use of PRA technology should be increased in all regulatory matters to the extent supported by the state-of-the-art in PRA methods and data and in a manner that complements the NRCs deterministic approach and supports the NRCs traditional defense-in-depth philosophy.
PRA and associated analyses (e.g., sensitivity studies, uncertainty analyses, and importance measures) should be used in regulatory matters, where practical within the bounds of the state-of-the-art, to reduce unnecessary conservatism associated with current regulatory requirements, regulatory guides, license commitments, and staff practices. It is, of course, understood that the intent of this policy is that existing rules and regulations shall be complied with unless these rules and regulations are revised.
Japan-OG-NRA-OCT-2024 24
- 4. Journey since (~1995)
Developing policies, tools, programs etc., to operate as a modern risk-informed regulator; Also leveraging human resources of industry organizations to develop implementing guidance Japan-OG-NRA-OCT-2024 25
A subset of ongoing Risk-Informed Initiatives in 2024 26 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
- 10 CFR 50.69 Implementation
- Crediting FLEX
- 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 26 Japan-OG-NRA-OCT-2024
Impact on safety due to risk-informing Issuance of the PRA Policy (1995) and the issuance of Revision 0 of RG 1.174 (1997) entitled An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis.
RG 1.74 was followed by the promulgation of a plethora of regulatory products (risk-informed voluntary options to rules, regulatory guides, etc.) that reduced unnecessary conservatisms which could cause very small increases in risk (small in comparison to subsidiary safety goals).
Dozens of new procedures were generated to enable risk-informing of most regulatory functions.
Very small potential increases in risk were negated by the safety gains associated with changes to plant designs and procedures identified during the implementation of some risk-informed alternatives.
Consequently, the NRC observed a continued increasing safety trend.
Japan-OG-NRA-OCT-2024 27
Motivating applicants to adopt NFPA 805, the risk-informed option to 10 CFR 50.48(b), is symbolic of additional safety gains that can be realized by continuing to risk-inform
- Installing incipient fire detection systems
- Eliminating the Self-Induced Station Blackout (SISBO) strategy
- Installation of safer Reactor Coolant Pump (RCP) seals
- Adding alternate RCP seal injection capability
- Improving batteries Example auxiliary feedwater NFPA-805 modification (Arkansas Nuclear One) 28 28 Japan-OG-NRA-OCT-2024
NRC has developed risk-informed guidance to implement regulatory functions highlighted 29 Regulations and Guidance
- Rulemaking
- Guidance Development
- Generic Communications
- Standards Development Oversight
- Inspection & Enforcement
- Performance Assessment
- Event response
- Allegations
- Investigations Support for Decisions
- Research Activities
- Advisory Activities
- Adjudication Licensing and Certification
- Licensing
- Certification Operational Experience
- Emergency Response
- Events Assessment
- Generic Issues Japan-OG-NRA-OCT-2024
Based on the ASP indicator, the Industry safety trend continues to improve using risk-informed initiatives that enabled removing unnecessary conservatisms.
Japan-OG-NRA-OCT-2024 30 Industry safety trend continues to improve using risk-informed initiatives that enabled removing unnecessary conservatisms.
Industry safety trend based on Nuclear Energy Institute (NEI)
Excerpt from NEI 20-04 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.
31 Japan-OG-NRA-OCT-2024
Challenges to risk-inform vary based on the application Japan-OG-NRA-OCT-2024 32 Use PRA inputs to design and license advanced reactor technologies.
Risk-informed Completion Times (TSTF-505)
Voluntary alternative to Fire Protection Regulation (10 CFR 50.48(c))
Risk-informed SSC categorization (10 CFR 50.69)
Risk-informed Surveillance Frequency Control program Risk-informed Inservice Inspection Risk-informed oversight (inspections, enforcement, event response)
Rigor of processes,
- tools, procedure, and human capital needed to implement the risk-informed initiative
An Example: Use of Risk-Informed ROP as a Stepping-Stone to Developing the PRA Infrastructure Transitioning from the SALP (1980-1998) process to the risk-informed ROP (1998) was a significant change.
It resulted in significant safety enhancement at some plants (plants with relatively high CDF were motivated to implement changes to reduce the significance of their findings).
It resulted in a substantial change in safety since inspection resources were targeted towards issues with high-risk significance.
It prompted both the NRC and the utilities to develop infrastructure relating to PRA (e.g., PRA models, Human Capital, risk-informed procedures) which could then be leveraged to implement other more complex risk-informed applications.
Japan-OG-NRA-OCT-2024 33
Risk-informed ROP provides an excellent starting point to develop a risk-informed infrastructure 34 Japan-OG-NRA-OCT-2024
Significance Thresholds 35 Green: Very low risk significance (e.g., Core Damage Frequency (CDF) 1.0E-6)
White: low to moderate risk significance (e.g., 1.0 E-6 < CDF 1.0E-5)
Yellow: substantial risk significance (e.g., 1.0E-5 < CDF 1.0E-4)
Red: high risk significance (e.g., CDF > 1.0E-4) 35 Japan-OG-NRA-OCT-2024
Action Matrix A graded approach to characterize performance and determine NRC response 36 36
- Increasing safety significance
- Increasing NRC inspection efforts
- Increasing NRC/licensee management involvement
- Increasing regulatory actions Japan-OG-NRA-OCT-2024
Some details on tools\\regulatory resources used by the US NRC to operate as a modern, risk-informed regulator and support approximately 100 nuclear power plants Key policies such as the PRA Policy and the Safety-Goal Policy.
Tools such as simplified PRA models that are accessible to staff for each operating facility.
Human capital:
Approximately 50 Reliability and Risk Analysts supporting the Office of Nuclear Reactor Regulation Approximately 50 Reliability and Risk Analysts supporting the Office of Nuclear Regulatory Research Approximately 10 Senior Reactor Analysts dedicated to supporting regional oversight activities.
A plethora of procedures that govern risk-informing almost all regulatory functions.
Japan-OG-NRA-OCT-2024 37
- 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.
Japan-OG-NRA-OCT-2024 38