Baltimore, Maryland Society of Women Engineers Annual Conference WE 13 October 24-26, 2013 A Post-Fukushima Look at Assessing Flood Hazards by Kit Y. Ng October 24 Lightning Talk Session CIVIL GOVERNMENT SERVICES MINING & METALS OIL, GAS & CHEMICALS POWER
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Baltimore, Maryland
Society of Women Engineers Annual Conference
WE 13 October 24-26, 2013
A Post-Fukushima Look at Assessing Flood Hazards
by
Kit Y. Ng
October 24 Lightning Talk Session
CIVIL GOVERNMENT SERVICESMINING & METALSOIL, GAS & CHEMICALS POWER
Overview
Fukushima Nuclear Accident - A Few Key Facts
Fukushima Lesson Learned and NTTF Recommendations
US Regulatory Actions
Impact to US Nuclear Fleet
Status of Flooding Reevaluation
Flooding Reevaluation Expectations
Fukushima Nuclear Accident – Key Facts March 11th@ 2:36 pm local
Magnitude 9.0 Earthquake 231 miles NE of Tokyo, 5th Largest Since 1900
First of Seven Tsunami Waves Arrived 41 Minutes Later
Source: INPO 11-005 November 2011 Special Report on the Nuclear Accident at the Fukushima Daiichi Nuclear Power Station
Post Fukushima Regulatory Actions - 2011
March 11 – NRC Operations Center to Monitor Tsunami Risk in US and Support Response Efforts
March 18 – NRC reminded Post-9/11 additional emergency equipment
March 23 – Resident inspectors re-examine Post-9/11 emergency equipment
April 1 – NRC Appointed Near Term Task Force (NTTF) on Fukushima Lessons Learned
April 29 - Resident inspectors examine severe accident management procedures and training at U.S. nuclear power plants per TI2515/184
May 11 - NRC requires nuclear power plants to provide information on post-9/11 emergency equipment, as well as how the plants ensure strategies to use the equipment remain effective over time (Bulletin 2011-01)
June 6 - NRC reports on areas for improvement regarding U.S. nuclear power plants’ Severe Accident Management Guidelines (SAMG)
July 12 – NRC NTTF Report on Lessons Learned from Fukushima Issued. Concluded that U.S. Plants are Operating Safely and Provided 12 Broad Recommendations for Enhancing Reactor Safety (SECY–11-093)
—Clarifying the Regulatory Framework - Defense-in-depth & Risk Considerations
9.3 Emergency preparedness regulatory actions (the remaining of Recommendation 9.3, except for Emergency Response Data System (ERDS) capability to be addressed in Tier 3
Present-Day Requirements Consistent with New Plant Licensing Requirements (ESP/COLA)
Guides and Standards: some new and some revised – RG1.59, RG1.102, RG1.206, SRP-0800, NUREG/CR-7046, ANS 2.8/1992; ISG on Storm Surge, Tsunami and Seiche; New ISG on Dam Break
Technology/Methodology – advanced from engineering judgments and simplified analytical hand calculations to 1D, 2D and 3D computational models
Flood Source Data
– Updated meteorological data such as Probable Maximum Precipitation– Updated hurricane data such as Probable Maximum Hurricane parameters– Updated tsunami source data
– Expect to require tsunami evaluation and modeling– Expect to require 2-D storm surge modeling – Expect to require consideration of sea-level changes
Streamside Sites:
– Probable Maximum Flood evaluation to consider higher hydrograph peaking factors per NUREG 7046; zero initial rainfall loss
– Sensitivity of Manning’s n, constant rainfall losses– Upstream dam failure evaluation (seismic/hydrologic/sunny day)– Downstream (Ultimate Heat Sink) dam failure as a result of upstream flooding– Consider blockages of drainages during local intense precipitation
– Updated NOAA HMR PMP values– Higher Resolution Topographic Data– Lower Rainfall Loss and Higher Peaking Factor– More Conservative Manning’s n values
Upstream dam failure level changes from -5 ft to +15 ft
– Selection of Breach Models– Changes in Dam inventories and Inflow Estimates– Adoption of more conservative but simpler computational approach for dry sites
Next Phase - Interim Measures and Integrated Assessments
Apply when Reevaluated Flood Hazards Exceed Current Design Basis
Need to Consider Other Associated Flood Hazards– Hydrostatic and Hydrodynamic Forces– Debris Loading; Sediment; Erosion– Flood Duration; Warning Time– Combined Effects of Multiple Flood Mechanisms
Higher Flooding Hazards Expected for Most Plants– Options: Protection vs Mitigation
Integrated Assessment – A New Process - Regulatory/Industry Guidance is being developed
Industry Group Task Force Involvement – NEI/EPRI/INPO/Utilities/Vendor
Peer Review Requirements; Human Performance Factor