ML22061A137
| ML22061A137 | |
| Person / Time | |
|---|---|
| Issue date: | 02/15/2022 |
| From: | Thomas Aird, Joseph Kanney, Elena Yegorova NRC/RES/DRA |
| To: | |
| Aird, Thomas - 301 415 2442 | |
| Shared Package | |
| ML22061A095 | List:
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| References | |
| Download: ML22061A137 (13) | |
Text
1 NRC Probabilistic Flood Hazard Assessment Research Program Update 7th Annual PFHA Research Workshop NRC HQ, Rockville, MD February 15 - 18, 2022 Thomas Aird*, Joseph Kanney, Elena Yegorova Fire and External Hazards Analysis Branch Division of Risk Analysis Office of Nuclear Regulatory Research
Outline
- Objectives, key challenges, approach
- Phase 1 Overview (Technical Basis)
- Phase 2 Projects (Pilot Studies)
- Thoughts on Phase 3 (Guidance) 2
PFHA Research Objectives
- Develop resources, tools and selected guidance to:
- Address significant gap in the technical basis for guidance for probabilistic assessment of external hazards
- Probabilistic: seismic, high winds
- Deterministic: flooding
- Support risk-informed licensing and oversight activities involving assessment of flooding hazards and potential consequences
- Licensing and oversight in operating reactor program
- Design basis flood hazard assessments for new facilities
- Readiness for licensing of advanced reactors 3
Key Challenges
- Hazard Estimation
- Range of annual exceedance probabilities (AEPs)
- Moderately rare to extreme floods
- Multiple flooding mechanisms
- Coincident and correlated mechanisms
- Uncertainty characterization and estimation
- Aleatory (e.g., storm recurrence rates)
- Epistemic (e.g., model structure, parameters)
- Fragility
- Information on reliability of flood protection features and procedures is sparse
- Cliff-edge effects 4
Magnitude Load Intensity Failure Probability
Phased Research Approach
- Phase 1 - Technical Basis Research - Complete
- Climate and precipitation
- Mechanistic, statistical and probabilistic modeling of flooding processes
- Reliability of flood protection features and procedures
- Modeling Frameworks
- Natural Hazard Information Digest (NHID)
- Phase 2 - Pilot Studies - In Progress
- Local Intense Precipitation (LIP) Flooding
- Riverine Flooding - Complete
- Coastal Flooding
- Phase 3 - Develop Guidance - In Progress 5
Phase 1 Technical Basis Projects Phase 3 Guidance Phase 2 Pilot Studies Application Inform &
update
Phase 1 Technical Basis Research Climate
Historical trends and future projections for U.S. regions Mechanistic, statistical and probabilistic modeling of flooding processes
Extreme precipitation
Riverine flooding
Coastal flooding Methods for Estimating Joint Probabilities of Coincident and Correlated Flooding Mechanisms
Riverine flooding
Coastal flooding Reliability of flood protection features and procedures
Flood barriers (seals, etc.)
Environmental effects on manual actions Modeling Frameworks Structured hazard assessment committee process for flooding (SHAC-F)
Dynamic analysis of flooding events USACE HEC-WAT Natural hazards information digest (for internal NRC staff use)
Collect and organize natural hazard information for operating reactors 6
For more details on Phase 1 completion see Digital Exhibit #11 at the 34th Annual Regulatory Information Conference (RIC), March 8-10, 2022:
https://www.nrc.gov/public-involve/conference-symposia/ric/index.html
Objective: Synthesize results from technical basis research
- Multiple flooding mechanism contribution to hazard curves
- Quantify key aleatory variabilities and epistemic uncertainties
- In Progress; completion expected in March 2022
- Riverine Flooding PFHA Pilot
- USACE/HEC
- Completed in January 2022
- Coastal Flooding Pilot PFHA Pilot
- USACE/ERDC/CHL
- In Progress; completion expected in June 2022 7
Phase 2: Pilot Studies
- Objectives
- Inform guidance development for probabilistic assessment of site-scale flooding hazards due to local intense precipitation
- Synthesize results from technical basis research
- Incorporate site-scale features (curbs, buildings, drains)
- Key elements
- Point rainfall (aleatory variability) based on NOAA Atlas 14
- Sensitivity study to identify key epistemic uncertainties wrt site features
- Propagation of uncertainties to construct hazard curve families for selected flood hazard metrics (e.g., depth, velocity, duration)
- Monte Carlo simulation with stratified sampling
- More detailed information:
- Presentation 2A-5 (Wednesday at 12:00) 8 Phase 2: LIP Pilot Study
- Objectives
- Inform guidance development for probabilistic assessment of riverine flooding hazards
- Synthesize results from technical basis research
- Incorporate multiple flooding mechanism contributions to hazard curves
- Key elements
- Stochastic rainfall model (aleatory variability)
- Epistemic uncertainties in hydrologic (runoff and routing), reservoir, and hydraulic models
- Multiple dam failure scenarios
- Propagation of uncertainties to construct hazard curve families for selected flood hazard metrics (e.g., elevation, velocity, duration)
- Monte Carlo simulation approach using HEC-WAT
- More detailed information:
- Presentation 2B-4 (Wednesday at 15:20)
- Posters 3A-4 and 3A-5 (Thursday at 10:00) 9 Phase 2: Riverine Pilot Study
Objectives
- Inform guidance development for probabilistic assessment of coastal flooding hazards
- Synthesize results from technical basis research
- Incorporate multiple flooding mechanism contributions to hazard curves Key elements
- Tropical cyclone rainfall model (aleatory variability)
- Epistemic uncertainties in hydrodynamic (surge),
hydrologic (runoff and routing), and hydraulic models
- Flooding due to surge and rainfall-induced riverine discharge
- Propagation of uncertainties to construct hazard curve families for selected flood hazard metrics (e.g., elevation, velocity)
- USACE Probabilistic Coastal Hazard Assessment (PCHA) framework More detailed information:
- Presentation 3B-3 (Thursday at 12:05) 10 Phase 2: Coastal Pilot Study
- FY 22/FY23: Develop draft guidance based on:
- Technical basis research
- Pilot projects
- User office needs
- Stakeholder & public interests
- FY23: Publish draft guidance for public comment
- FY23: Finalize guidance based on public comment 11 Phase 3: PFHA Guidance
- NRC Research Information Letter (RIL) 2020-01
- Proceedings of 5th Annual NRC PFHA Research Workshop
- Proceedings of 6th Annual NRC PFHA Research Workshop
- RIL 2022-02 NRC Research Information Letters are available at:
https://www.nrc.gov/reading-rm/doc-collections/index.html#ril 12 Past Workshops
13 Questions?
Contacts:
Joseph.Kanney@nrc.gov Thomas.Aird@nrc.gov Elena.Yegorova@nrc.gov