ML20080M178

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PFHA-2020-1A-2-Aird-NRC-PFHA-Research-Overview-2020 Clean Copy
ML20080M178
Person / Time
Issue date: 03/23/2020
From: Thomas Aird, M'Lita Carr, Mark Fuhrmann, Joseph Kanney, Elena Yegorova
Office of Nuclear Regulatory Research
To:
Office of Nuclear Regulatory Research
T. Aird
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1 Overview of NRCs Probabilistic Flood Hazard Assessment Research Program 5th Annual PFHA Research Workshop NRC HQ, Rockville, MD February 19 - 21, 2020 Thomas Aird*, Meredith Carr, Mark Fuhrmann, Joseph Kanney, Elena Yegorova Fire and External Hazards Analysis Branch Division of Risk Analysis Office of Nuclear Regulatory Research

Outline

  • Objectives
  • Key Challenges
  • Research Approach
  • Selected Projects
  • Future Directions 2

PFHA Research Objectives

  • Address significant gap in technical basis for guidance for probabilistic assessment of external hazards

- Probabilistic: seismic, high winds

- Deterministic: flooding

  • Develop resources, tools and selected guidance

- Support risk-informed licensing and oversight activities associated with flooding hazards and 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 Curve Development

- 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 Curve Development

- Information on reliability of flood protection features and procedures is sparse

- Cliff-edge effects 4

Magnitude Load Intensity Failure Probability

Phased Approach

  • Phase 1 (FY15-FY19)

- Technical basis research

  • Phase 2 & 3 (FY20-FY22)

- Selected draft guidance documents

- Perform pilot studies

- Finalize guidance 5

6 Phase 1 Technical Basis Projects Leverage Available Flood Information PFHA Modeling Frameworks Improved Modeling Reliability of Flood Protection Dynamic and Nonstationary Processes

7 Phase 1 Technical Basis Projects Leverage Available Flood Information PFHA Modeling Frameworks Improved Modeling Reliability of Flood Protection Dynamic and Nonstationary Processes

Leverage Available Flooding Information

  • Development of Natural Hazard Information Digests for Operating NPP Sites (INL)

- Completed (continue with updates/maintenance)

  • Application of State-of-Practice Flood Frequency Analysis Methods and Tools (USGS)

- Completed - USGS Scientific Investigation Report

- https://pubs.er.usgs.gov/publication/sir20175038

- 2nd USGS SIR in publication

  • Extreme Precipitation Estimates in Orographic Regions (USBR)

- Completed - NUREG/CR report in publication

  • Technical Basis for Extending Frequency Analysis Beyond Current Consensus Limits (USBR)

- In progress (completion expected in FY20) 8

  • Eastern US Riverine Flood Geomorphology Feasibility Study (USGS)

- Completed - USGS Scientific Investigations Report

  • Eastern US Riverine Flood Geomorphology Comprehensive Study (USGS)

-In progress (completion expected FY20)

  • Framework for Technical Review of Paleoflood Information (USGS)

-In progress (completion expected FY20)

  • Application of Point Precipitation Estimates to Watersheds (ORNL)

-Completed (NUREG/CR report in publication) 9 Leverage Available Flooding Information

10 Phase 1 Technical Basis Projects Leverage Available Flood Information PFHA Modeling Frameworks Improved Modeling Reliability of Flood Protection Dynamic and Nonstationary Processes

PFHA Modeling Frameworks

  • Probabilistic Flood Hazard Assessment Framework Development (USACE)

- In progress (completion expected FY20)

  • Structured Hazard Assessment Committee Process for Flooding (SHAC-F) for LIP & Riverine Flooding (PNNL)

- In progress (completion expected FY20)

  • Development of SHAC-F for Coastal Flooding (PNNL &

USACE)

- In progress (completion expected FY20)

  • Methods for Estimating Joint Probabilities of Coincident and Correlated Flooding Mechanisms for Nuclear Power Plant Flood Hazard Assessments (ORNL)

- In progress (completion expected FY20)

  • Task 1 (Literature review) completed
  • Task 2 (Critical Assessment of Selected Methods and Approaches) Completed.

11

12 Phase 1 Technical Basis Projects Leverage Available Flood Information PFHA Modeling Frameworks Improved Modeling Reliability of Flood Protection Dynamic and Nonstationary Processes

Numerical Modeling of Local Intense Precipitation Processes (USGS/UC Davis)

- Completed - NUREG-CR report in publication

- Peer-reviewed papers: Mure-Ravaud, et al. (2019a,b) https://www.sciencedirect.com/science/article/pii/S0048969719306734

- https://www.sciencedirect.com/science/article/pii/S0048969719306291 Quantifying Uncertainties in Probabilistic Storm Surge Models (USACE)

- In Progress (completion expected FY20)

- Task 1 (Literature Review) Completed. ERDC/CHL SR-19-1

- Task 2 (Storm Recurrence Rate Models) Completed. ERDC/CHL TR-19-4

- Completed - NUREG-CR report in publication Convection-Permitting Modeling for Intense Precipitation Processes (NCAR)

- In Progress (completion expected FY21) 13 Improved Modeling

14 Phase 1 Technical Basis Projects Leverage Available Flood Information PFHA Modeling Frameworks Improved Modeling Reliability of Flood Protection Dynamic and Nonstationary Processes

  • Modeling Plant Response to Flooding Events (INL)

- Completed. NUREG/CR report in publishing

  • Effects of Environmental Factors on Manual Actions for Flood Protection and Mitigation at Nuclear Power Plants (PNNL)

- Completed. NUREG/CR report in publication process

- Completed. ORNL report available at https://www.osti.gov/biblio/1592163-current-state-practice-dam-safety-risk-assessment

  • Performance of Flood Penetration Seals at NPPs (Fire Risk Management, Inc.)

- Completed. NUREG report in publication process

  • Flood Barrier Testing Strategies (INL/ISU)

- In Progress. Public workshop to be held March 12 - 13 15 Reliability of Flood Protection

16 Phase 1 Technical Basis Projects Leverage Available Flood Information PFHA Modeling Frameworks Improved Modeling Reliability of Flood Protection Dynamic and Nonstationary Processes

Dynamic and Nonstationary Processes

  • Regional Climate Change Projections: Potential Impacts to Nuclear Facilities (PNNL)

- Year 1 (CONUS) - Complete

  • published as a PNNL report (PNNL-24868)

- Year 2 (Southeast US) - Complete

  • published as a PNNL report (PNNL-26226)

- Year 3 (Midwest US) - Complete

  • published as a PNNL report (PNNL-27452 Rev1)

- Year 4 (Northeast US) - Complete

  • published as a PNNL report (PNNL-29079) 17

18 Future Directions for PFHA Phase 1 Technical Basis Projects Phase 2 Pilot Projects Application Inform & update Phase 3 Guidance

19 Future Directions for PFHA Phase 1 Technical Basis Projects Phase 2 Pilot Projects Application Inform & update Phase 3 Guidance

Objective: Synthesize results from technical basis research

- Multiple flooding mechanism contribution to hazard curves

- Quantify key aleatory variabilities and epistemic uncertainties LIP Flooding PFHA Pilot (PNNL)

- Pilot study to inform development of guidance for probabilistic assessment of flooding hazards at NPPs due to local intense precipitation events Riverine PFHA Pilot (USACE/HEC)

Coastal Flooding Pilot PFHA Pilot (USACE/ERDC) 20 Phase 2 Pilot Studies

  • Revise guidance documents based on pilots
  • Stakeholder & Public Interactions
  • Finalize guidance 21 Phase 3 (FY22-?)

Questions?

Contact:

joseph.kanney@nrc.gov Phase 1 Technical Basis Projects Phase 2 Pilot Projects Application Inform & update Phase 3 Guidance

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