ML20244A263
| ML20244A263 | |
| Person / Time | |
|---|---|
| Issue date: | 09/16/2020 |
| From: | Bauer L, Hill B, Gerry Stirewalt, Jacqueline Thompson NRC/NRR/DEX/EXHB |
| To: | |
| Jenise Thompson 415-1811 | |
| References | |
| Download: ML20244A263 (14) | |
Text
The Reactor and the Volcano: A Risk-Informed Approach of the NRC to Assess Volcanic Hazards at New Nuclear Reactor Sites Jenise Thompson Gerry L. Stirewalt Brittain Hill Laurel M. Bauer 2020 AEG Annual Meeting
Regulatory Requirements
- 10 CFR Part 50, Appendix A, General Design Criteria for Nuclear Power Plants, General Design Criterion 2
- 10 CFR 52.17(a)(1)(vi) for an early site permit and 10 CFR 52.79(a)(1)(iii) for a combined license
- 10 CFR 100.23, Reactor Site Criteria 2
Prior NRC Reviews 3
NRC Regulatory Guides
Develop
- Must consider international standards DG
- 60-day comment period Public
- Disposition all comments Comments
- Revise DG, as appropriate Finalize
- ACRS (optional)
RG 4
- 1) Gather Initial Information
- Time Period of Interest
- Quaternary (<2.6 Ma)
- Region of Interest
- 200 mile radius, farther for ashfall hazard
- Consistent with active tectonic and magmatic system 5
- 2) Deterministic Screening
- Volcano characteristics in region of interest
- Analogues or models to reduce uncertainties
- Screen based on maximum distance hazard could travel from source 6
- 3) Initial Risk Insights
- A suite of risk-informed information to judge the safety significance of new information
- Evaluate vulnerability if probability of hazard = 1 at site
- Consider risk-insight information, including uncertainty & alternatives 7
- 4) Eruption or Hazard Likelihoods
- Evaluate either Probability of eruption (PE) or of hazard (PH)
- Character of past events may be more certain than timing
- Use Senior Seismic Hazard Analysis Committee process to consider uncertainties from erosion, burial, interpretation, modeling etc.
8
- 5) Detailed Risk Insights
- Same approach as Step 3
- Evaluate vulnerability if hazard = PE and/or PH at site
- Consider risk-insight information, including uncertainty & alternatives 9
- 6) Evaluate Design Bases
- Optional Step
- Develop more accurate limit states for Structures, Systems and Components
- Exceedance likelihoods for hazard demands
- Actual material properties
- Facility-specific SSCs
- Re-evaluate risk insights
- Allows for enhancing design basis 10
- 7) Evaluate Mitigation Actions
- Hours to weeks of warning before eruptions
- Columbia Generating Station, WA
- Ash-fall hazard from Cascades, >200 km away
- Hours to prepare
- Air filtration, maintenance procedures
- Ash-fall is a commonly mitigated hazard world-wide 11
Siting Considerations
- If hazard cannot be mitigated through design or operations, alternative sites should be investigated
- Volcanic hazards often are spatially restricted
- Sites with acceptable risk might be located within several km or less 12
Public Comments
- NRC Staff is in the process of dispositioning the public comments received
- Consider the use of a geographic screening criteria
- Clarification of how risk insights and PRA information is used in the VHA
- Treatment of large sources like Yellowstone
- Clarification on the use of the SSHAC process in the VHA 13
Future Plans
- Public meeting on comment disposition
- Solicit feedback from stakeholders on content and use of guide to develop application
- Revise draft guide before issuing as final Regulatory Guide
- DG-4028 is available in ADAMS -
ML20007D621 Inquiries: Jenise.Thompson@nrc.gov 14