ML22049B546

RIC 2022 Digital Exhibit 11 Research Update: Completion of Phase 1 Probabilistic Flood Hazard Assessment (PFHA) Research

ML22049B546
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Issue date:	03/08/2022
From:	Thomas Aird, Joseph Kanney, Elena Yegorova NRC/RES/DRA
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Research Update: Office of Nuclear Regulatory Research Completion of Phase 1 Probabilistic Flood Hazard Assessment (PFHA) Research

PFHA Research Objectives

• Provide the technical basis for guidance for probabilistic assessment of external flooding hazards

• Support risk-informed licensing and oversight activities involving assessment of flooding hazards and potential consequences

• Develop resources, tools, and selected guidance

• See final slide for credits Phase 1 (Technical Basis) Elements Phase 1 research focused on topics related to the technical basis for statistical and probabilistic modeling of selected flooding processes of interest at nuclear power plants and other commercial nuclear facilities:

• Climate and precipitation

• Mechanistic, statistical, and probabilistic modeling of

+ Riverine coastal flooding processes

+ Coastal flooding processes

• Combined flooding mechanisms

• Modeling frameworks

• Reliability of flood protection features and procedures

The Phase 1 research leveraged contract technical support from other Federal agencies and private contractors, as well as subcontracts and grants to academic researchers, such as the following:

Climate The NRC and PNNL staff prepared four annual reports that summarize recent scientific findings about global and regional climate change, focusing on climatic elements that are relevant to NRC staff concerns on a regional level (i.e., increasing air and water temperatures, decreasing water availability, increasing *See final slide for credit frequency and intensity of storms and flooding, and sea-level rise).

• First Annual Report: CONUS (PNNL-24868) https://www.osti.gov/biblio/1259942

• Second Annual Report: Southeast US (PNNL-26226 Rev 1) https://www.osti.gov/biblio/1593340

• Third Annual Report: Midwest US (PNNL-27452 Rev1) https://www.osti.gov/biblio/1524249

• Fourth Annual Report: Northeast US (PNNL-29079) https://www.osti.gov/biblio/1605280 Precipitation

The NRC worked with other Federal agencies, national laboratories, and university researchers to investigate statistical and numerical simulation approaches for modeling extreme precipitation.

• See final slide for photo credit

• Mure-Ravaud, et al. 2019a. Numerical reconstruction of the intense precipitation and moisture transport fields for six tropical cyclones affecting the eastern United States. https://www.sciencedirect.com/science/article/pii/S0048969719306734

• Mure-Ravaud, et al. 2019b. Physically based storm transposition of four Atlantic tropical cyclones.

https://www.sciencedirect.com/science/article/pii/S0048969719306291

• Kao, et al. 2020. Variability of precipitation areal reduction factors in the conterminous United States.

https://www.sciencedirect.com/science/article/pii/S2589915520300158

• NUREG/CR-7247. Research to Develop Guidance on Extreme Precipitation Frequency Estimates in Orographic Regions (in publication).

• NUREG/CR-7271. Application of Point Precipitation Frequency Estimates to Watersheds. https://www.nrc.gov/reading-rm/doc -

collections/nuregs/contract/cr7271/index.html

• NUREG/CR-7278. Numerical Simulation of Local Intense Precipitation Processes (in publication).

• NUREG/CR-7290. Convection-Permitting Modeling for Intense Precipitation Processes (in publication).

Riverine Flooding The NRC staffs research focused on statistical modeling methods and application of paleoflood hydrology approaches for estimating extreme riverine floods.

• USGS Scientific Investigations Report (SIR)-2017-5038. Application of At -Site Peak -Streamflow Frequency Analyses for Very Low An nual Exceedance Probabilities.

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

• USGS SIR-2020-5065. Flood-Frequency Estimation for Very Low Annual Exceedance Probabilities Using Historical, Paleoflood, and Regional Information with Consideration of Nonstationarity. https://doi.org/10.3133/sir20205065

• NRC Research Information Letter (RIL) 2022-04. Technical Basis for Extending Flood Frequency Curves Beyond Current Consensus Lim its (in publication).

• USGS SIR 2014-5207. Assessing inundation hazards to nuclear powerplant sites using geologically extended histories of riverine f loods, tsunamis, and storm surges.

https://pubs.er.usgs.gov/publication/sir20145207

• USGS SIR-2017-5052. Prehistoric floods on the Tennessee River Assessing the use of stratigraphic records of past floods for impr oved flood-frequency analysis.

https://doi.org/10.3133/sir20175052

• USGS SIR-2020-5138. Improving Flood-Frequency Analysis with a 4,000-Year Record of Flooding on the Tennessee River near Chattano oga, Tennessee.

https://pubs.er.usgs.gov/publication/sir20205138

• USGS Techniques and Methods Report 4-B6. Historical and Paleoflood Analyses for Probabilistic Flood-Hazard AssessmentsApproaches and Review Guidelines.

https://doi.org/10.3133/tm4B6 Coastal Flooding The NRC staff worked with the USACE to perform a detailed investigation of *See final slide for photo/figure credits uncertainty in probabilistic modeling of storm surge due to hurricanes, tropical storms, and extratropical storms.

• Engineer Research and Development Center (ERDC) -Coastal and Hydraulics Laboratory (CHL) SR-19-1. Quantification of Uncertainty in Probabilistic Storm Surge Models: Literature Review. https://erdc-library.erdc.dren.mil/xmlui/handle/11681/32295

• ERDC-CHL TR 4. Storm Recurrence Rate Models for Tropical Cyclones: Report 1 of a series on the Quantification of Uncertainties in Probabilistic Storm Surge Models. https://erdc-library.erdc.dren.mil/xmlui/handle/11681/32824

• ERDC-CHL Technical Report. Data, Models, and Methods for Defining Joint Probability of Storm Parameters and Generating Synthetic Storm Simulation Sets (in publication).

• ERDC-CHL Technical Report. Probabilistic Modeling of Numerical Surge Estimation Errors ( in publication).

Flood Protection/Mitigation The NRC staff worked with national laboratories and private industry consultants to review the state-of-practice in dam safety risk assessment.

The NRC staff also investigated the feasibility of, and strategies for, testing of nuclear power plant flood barriers, and the effects of environmental conditions on flood response at nuclear power plants.

• ORNL/TM-2019/1069. Current State-of-Practice in Dam Safety Risk Assessment. https://doi.org/10.2172/1592163

• NUREG/CR-7256. Effects of Environmental Conditions on Manual Actions for Flood Protection and Mitigation.

https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7256/

• NUREG-2240. Flood Penetration Seal Testing Protocol Research ( in publication).

• NUREG/CR-7279. Research to Develop Flood Barrier Testing Strategies for Nuclear Power Plants (in publication).

Combined Flooding Mechanisms

The NRC staff worked with ORNL and UMD to review the state-of-practice in multimechanism flood hazard assessment (i.e., joint probability of flooding events due to coincident or correlated flooding processes). Case studies investigated application of copula-based and Bayesian-motivated approaches. *Figure from ORNL/TM-22/1447

• ORNL/TM-2020/1447. Multi-Mechanism Flood Hazard Assessment: Critical Review of Current Practice and Approaches. https://doi.org/10.2172/1637939

• ORNL/TM-2021/2231. Multi-Mechanism Flood Hazard Assessment: Example Use Case Studies.

https://doi.org/10.2172/1826019

• NUREG/CR-7296. Multi-Mechanism Flood Hazard Assessment: Critical Review of Current Practice and Approaches and Example Use Case Studies ( in publication).

Modeling Frameworks The NRC worked with

• USACE to investigate statistical and numerical simulations frameworks for flood hazard assessment

• PNNL to adapt the Senior Seismic Hazard Analysis Committee process for addressing uncertainty in flooding assessments

• INL to focus on a dynamic probabilistic risk assessment approach for flooding risk assessment

• ERDC/CHL TR-19-14. Probabilistic Flood Hazard Assessment Framework Development: Extreme Rainfall Analysis. https://erdc-library.erdc.dren.mil/jspui/handle/11681/33883

• ERDC/CHL TR-20-7. Analysis of Snow Water Equivalent Annual Maxima in the Upper Connecticut River Basin Using a Max -Stable Spatial Process Model. https://erdc-library.erdc.dren.mil/jspui/handle/11681/36415

• USACE/HEC Technical Report. Probabilistic Flood Hazard Assessment Framework: Riverine Flooding HEC-WAT Case Study (in publication).

• NUREG/CR-7292. Structured Hazard Assessment Committee Process for Flooding (SHAC -F) for Local Intense Precipitation, Riverine, and Coastal Flooding (in publication).

• NRC RIL 2022-03. A Simulation-Based Dynamic Analysis Approach for Modeling Plant Response to Flooding Events (in publication).

Participation PFHA Research Workshops Typically 100- 300 Participants

• The NRC has organized and hosted seven Annual PFHA Research Workshops (2015-2022).NRC External

• Presenters have included NRC staff and contractors, as well as participants from Federal agencies, industry, and other domestic and international organizations.

• Presentations provide information on current activities, recent results, and perspectives on future research directions in flood hazard assessment, flood protection/mitigation, and NRC Participation flood risk assessment. Other RES

• The workshops have also included discussion of nonseismic external hazards such as Regions extreme temperatures and high winds. NMSS NRR

The NRC publishes PFHA workshop proceedings as NRC Research Information Letters (RILs):

• 1st-4th Annual Workshops: RIL 2020- 01External Participation

• 5th Annual Workshop: RIL 2021- 01International

- 02AcademicIndustry

• 6th Annual Workshop: RIL 2022

• 7th Annual Workshop: In preparation Government Whats Next?

Phase 2Pilot Studies Three pilot studies are being conducted to demonstrate probabilistic flood hazard curve development for common flooding scenarios:

• Local Intense Precipitation Flooding PFHA Pilot Studycompletion expected in second quarter 2022

• Riverine Flooding PFHA Pilot Studystudy completed in January 2022 (report in publication)

• Coastal Flooding PFHA Pilot Studycompletion expected in second quarter 2022

Phase 3Develop and Publish Regulatory Guidance

• Scope and format for regulatory guidance on PFHA methods is currently under discussion with internal stakeholders.

• Publication of draft guidance for public comment is expected in fiscal year 2023.

Contact Information

Joseph Kanney Joseph.Kanney@nrc.gov

Elena Yegorova Elena.Yegorova@nrc.gov

Thomas Aird Thomas.Aird@nrc.gov Photo/Figure Credits Photos/figures used are in the public domain with the following exceptions:

Slide 1 Top left figure adapted from National Weather Service https://www.weather.gov/grb/Harvey Slide 3Figure from https://en.wikipedia.org/wiki/Climate_change (unchanged)

Slide 4Photo from https://en.wikipedia.org/wiki/Rain (unchanged)

Slide 6Figure from National Hurricane Center https://www.nhc.noaa.gov/surge/

Slide 6Photo from NASA Earth Observatory https://earthobservatory.nasa.gov/images/4369/hurricane-catarina-hits-brazil