ML20310A277
| ML20310A277 | |
| Person / Time | |
|---|---|
| Issue date: | 11/05/2020 |
| From: | Sunil Weerakkody NRC/NRR/DRA |
| To: | |
| sunil weerakkody | |
| References | |
| Download: ML20310A277 (17) | |
Text
Safety Risk Metrics for Light Water Reactors and Advanced Light Water Reactors Presented at Institute of Nuclear Material Management Conference on Risk-Informing Security using Safety Risk Information (NRC Public ADAMS Accession No. ML20310A277)
November 9-11, 2020 The Pennsylvania State University Sunil D. Weerakkody**
Senior Level Advisor Division of Risk Assessment Office of Nuclear Reactor Regulation
- Views presented by the author do not represent formal US NRC Positions.
BG1
Slide 1 BG1 Add "Water" between "Light" and "Reactors."
Remove period after "Information" In the note at the bottom, replace "does" with "do."
Bowman, Greg, 11/4/2020
OUTLINE US NRC objectives and strategies to risk-inform safety and security Risk Triplet, Safety Goals and Quantitative Risk Metrics Conceptual approach for leveraging PRA tools that support safety to risk-inform security Risk-Informing security: Recent examples of incremental successes Conclusions 2
BG2
Slide 2 BG2 Remove period after first bullet.
Consistent capitalization in the bullets.
Bowman, Greg, 11/4/2020
US NRC Strategic Plan and Mission on Nuclear Safety and Security NRC 2018-2022 Strategic Plan:
The Commission as a whole formulates policies and regulations governing the safety and security of nuclear facilities and radioactive materials, issues orders to licensees, and adjudicates legal matters brought before it.
US NRC Mission:
The NRC licenses and regulates the Nations civilian use of radioactive materials to provide reasonable assurance of adequate protection of public health and safety and to promote the common defense and security and to protect the environment.
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Slide 3 BG3 Remove empty text boxes below each bubble.
Bowman, Greg, 11/4/2020
Accomplishing Safety Mission Safety Strategies Safety Objectives Safety Goal Mission 4
Accomplishing Security Mission Security Strategies Security Objectives Security Goal Mission 5
SAFETY GOAL, OBJECTIVES, AND STRATEGIES 6
- Safety Objective 1:
Prevent, Mitigate, and Respond to Accidents and Ensure Radiation Safety.
- Safety Strategy 2:
Further risk-inform the current regulatory framework in response to advances in science and technology, policy decisions, and other factors, including prioritizing efforts to focus on the most safety-significant issues.
- Safety Strategy 4:
Maintain effective and consistent oversight of licensee performance with a focus on the most safety significant issues Safety Strategic Goal:
Ensure the safe use of nuclear materials
SECURITY GOAL, OBJECTIVES, AND STRATEGIES 7
- Security Objective 1: Ensure Protection of Nuclear Facilities and Radioactive Materials.
- Security Strategy 1: Maintain and further risk-inform the current regulatory framework for security using information gained from operating experience, lessons learned, external and internal assessments, technology advances, and changes in the threat environment.
- Security Strategy 2: Maintain effective, consistent, and risk-informed oversight of licensee performance with respect to meeting NRC security requirements.
Security Strategic Goal:
Ensure the secure use of nuclear materials Security Strategic Goal:
Ensure the secure use of nuclear materials
What is a Risk Assessment?
A systemic method for addressing the risk triplet as it relates to the performance of a particular system (which may include a human component) to understand likely outcomes, sensitivities, areas of importance, system interactions and areas of uncertainty.
Source: US NRC SECY 98-0144 8
Risk Triplet What can go wrong?
How likely it is?
What are the consequences?
Evolution of Quantitative Risk Metrics WASH-1400 (1975)
NRC Safety Goal Policy (1986):
Qualitative and Quantitative Safety Goals Risk Metrics in Core Damage Frequency (CDF) and Large Early Release Frequency (LERF)
Evolution of large numbers of methods, models, data sources over five decades 9
US NRC Safety Goal Policy (1986) and Risk Metrics Used to Set Acceptable Thresholds in Licensing and Oversight of Light Water and Advanced Light Water Reactors The Quantitative Health Objectives (QHO) for Early Fatalities is ~
5x10-7/year; 0.1% of the prompt risk fatality risk to an average individual in the vicinity of a nuclear power plant.
NRCs subsidiary goal for the above QHO, (LERF) for operating reactors is 1x10-5 /year. For advanced light water reactors this value is 1x10-6 /year (design goal).
The QHO for latent cancer fatalities is ~ 2x10-6/year; 0.1% of the cancer risk to the population in the area near (ten miles) a nuclear power plant.
NRCs subsidiary goal for the above QHO, (CDF) for operating and new reactors, is 1x10-4 /year.
11/10
/2020 Sources: NRC Safety Goal Policy (1986) 10
Components of Risk Assessments 11 What can go wrong?
Plant transients, loss of coolant accidents caused by internal (e.g. reactor trips) or external (e.g.
earthquakes) events.
How likely is it? (Frequency of events)
Probability of failure of mitigating systems and barriers What are the consequences?
Early and latent health effects BG6
Slide 11 BG6 Same comment as on the previous similar slides.
Remove comma after "trips" and add comma after the first "e.g."
"Early" in the last block should be lower case.
Also, suggest combining the two "How likely is it?" blocks.
Bowman, Greg, 11/4/2020
Risk-Informing Security: Example of Recent NRC Activities Issued letter on industry use of focused cyber guidance to better risk-inform rule implementation for emergency preparedness digital assets, based on lessons learned from implementation and oversight of the NRCs cyber security requirements (ADAMS Accession No. ML20129J981).
Issued letter on industry use of focused cyber guidance to better risk-inform rule implementation for balance of plant digital assets, based on lessons learned from implementation and oversight of the NRC cyber security requirements (ADAMS Accession No. ML20209A442).
Issued letter on industry use of focused cyber guidance to better risk-inform rule implementation for important-to-safety and safety-related digital assets, based on lessons learned from implementation and oversight of the NRCs cyber security requirements (ADAMS Accession No. ML20223A256).
Finalized a process for licensees to use to allow a risk-informed methodology for establishing physical security compensatory measures based on site-specific threat conditions. This initiative involved extensive coordination with NRC resident and regional inspectors and licensee security managers to ensure mutual understanding of the revised process included in the NRC endorsement letter (ML18137A359).
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Conclusions
- US NRC continues to meet the strategic safety and security goals.
- US NRC continues to pursue options to risk-inform safety and security in support of the strategic goals.
- Leveraging PRA tools that support safety to risk-inform security remains a challenge.
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