ML24248A215
| ML24248A215 | |
| Person / Time | |
|---|---|
| Issue date: | 09/04/2024 |
| From: | Jacqueline Thompson Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| Download: ML24248A215 (1) | |
Text
Adapting Successful Hazard Analysis Approaches to New Hazards at the Nuclear Regulatory Commission Jenise Thompson, PMP September 12, 2024 Association of Environmental and Engineering Geologists Annual Meeting Outline
- Statutory role of NRC
- Regulatory requirements for new reactor applications
- Success Stories
- Applying SSHAC to Volcanic Hazards
- Incorporating Engineering Judgement in Flooding Analyses
2 NRC Mission
The NRC licenses and regulates the Nation's 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.
3 Regulatory Requirements
- 10 CFR Part 50, Appendix A, General Design Criteria for Nuclear Power Plants, General Design Criterion 2
- Must consider the effects of natural phenomena without loss of capability to perform their safety function
- Consider the most severe phenomena that have been historically reported for the site and surrounding area.
- 10 CFR 100.23(c), Reactor Site Criteria
- investigate all geologic and seismic factors (for example, volcanic activity) that may affect the design and operation of the proposed nuclear power plant
4 Applying SSHAC to Volcanic Hazards
Endorsing a successful seismic hazard approach for another hazard SSHAC Overview
- Senior Seismic Hazard Analysis Committee (SSHAC) approach to guide expert elicitation of hazard information to develop a probabilistic hazard assessment
- Considers the Center, Body and Range of the Technically-Defensible Interpretations (CBR of the TDI)
- NRC guidance on the process
-NUREG-2213
6 SSHAC Essentials
- 1. Clearly defined roles
- 2. Objective evaluation of existing data and models
- 3. Integration to capture the best estimates and the range of uncertainty
- 4. Clear and transparent documentation
- 5. Independent participatory peer review
Additional information provided in NUREG-2213
7 SSHAC Study Levels
- Determined by scope of review and available information
- Level 2 can be used for site specific project relying on regional SSHAC Level 3 studies.
- Higher level studies can have greater regulatory assurance and longevity.
- Levels 3 and 4 differ in project organization, not outcome
8 SSHAC as a Framework Model for Multiple Hazards
9 Incorporating Engineering Judgement in Flood Hazard Analyses
Modifying the approach for volcanic hazards to assess flood hazards at advanced and small modular reactor sites Regulatory Guide 4.26, Volcanic Hazards Assessment for Proposed Nuclear Power Reactors
11 RG 1.59, Design Basis Floods for Nuclear Power Plants
- RG 1.59, Revision 2, issued in 1977
- Revision 3 initially issued for public comment as DG-1290 in 2022, reissued for public comments July 15, 2024
- Appendix K adapts methodology from RG 4.26 for advanced reactor and small modular reactor applicants.
12 What can we adapt from RG 4.26?
- Flexible, stepwise approach with multiple off-ramps
13 What can we adapt from RG 4.26?
- Flexible, stepwise approach with multiple off-ramps
- Leverage existing site characterization information
14 What can we adapt from RG 4.26?
- Flexible, stepwise approach with multiple off-ramps
- Leverage existing site characterization information
- Screen hazards and consider risk insights
15 What can we adapt from RG 4.26?
- Flexible, stepwise approach with multiple off-ramps
- Leverage existing site characterization information
- Screen hazards and consider risk insights
- Evaluate SSC performance and mitigating actions in addition to or in place of detailed hazard analysis
16 From RG 4.26 to DG-1290
RG 4.26, Figure 1 DG-1290, Figure K-117 Appendix K Flowchart
- Step 1 - leverage site characterization information
- Step 2 - determine which, if any, flood-causing mechanisms affect plant performance
- Step 3 - determine if there is adequate engineering for SSCs to withstand the hazard
- Step 4 - evaluate mitigating actions for adequacy
- Step 6 - reassess design features and/or consider PRA
- Step 5 - assessment complete and results documented Figure K-1, DG-1290, Rev. 1 18 Appendix K Summary
- End the flood evaluation at the earliest possible point in the process.
Figure K-1, DG-1290, Rev. 1
19 Appendix K Summary
- End the flood evaluation at the earliest possible point in the process.
- Focus on flood causing mechanisms of importance to the design
Figure K-1, DG-1290, Rev. 1
20 Appendix K Summary
- End the flood evaluation at the earliest possible point in the process.
- Focus on flood causing mechanisms of importance to the design
- Consider PRA or comparable analysis
Figure K-1, DG-1290, Rev. 1
21 Appendix K Summary
- End the flood evaluation at the earliest possible point in the process.
- Focus on flood causing mechanisms of importance to the design
- Consider PRA or comparable analysis
- Iterate between evaluation of SSCs performance and mitigating actions and design reassessment to achieve satisfactory result.
Figure K-1, DG-1290, Rev. 1
22 What comes next?
Volcanic Hazards Flooding Hazards
- First-of-a-kind V-SSHAC results used to
- DG-1290 Public Comment period inform NRC permit or license closes September 13, 2024 application
- Public comments will be dispositioned
- Revision of RG 4.26 to clarify use of
Applying similar approaches to external hazard reviews for advanced reactors, small modular reactors and microreactor applications.
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