Fukushima Daiichi Nuclear Power Station Accident April19 2011
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This document provides an overview of the Fukushima Daiichi nuclear accident that occurred in 2011 following an earthquake and tsunami in Japan. It discusses the plant designs, accident progression, spent fuel pools, radiological releases, and impact on US reactors. Key events included the loss of off-site power and emergency diesel generators due to flooding, melting of reactor cores due to lack of cooling, hydrogen explosions, and venting of radioactive gases. Lessons learned included enhancing backup cooling capabilities and emergency procedures for extreme events.
Fukushima Daiichi Nuclear Power Station Accident April19 2011
- 1. By Joseph S. Miller EDA, Inc
- 2. Introduction Over 35 Years in the Nuclear Power Industry MS Nuclear, BS Mechanical, BS Industrial Worked at a BWR Nuclear Power Station for 9 years. Responsible for Fuel, safety analyses and PRA. Responsible for Nuclear Steam Supply Systems Technical Support Manager for Emergency Response Organization. Supported the Nuclear Regulatory Commission (NRC) in reviewing Nuclear Power Plant Safety Systems.
- 3. Acknowledgements Thanks to Japanese Industrial Atomic Forum (JIAF) Tokyo Electric Power Company (TEPCO) AREVA PowerPoint- The Fukushima Daiichi Incident Dr. Matthias Braun Nuclear and Industrial Safety Agency (NISA) & Japan Nuclear Energy Safety Organization (JNES) on Plant Data Lake H. Barrett- Foundation For Nuclear Studies Briefing General Electric
- 4. The Fukushima Daiichi Accident 1. What Happened? 2.Plant Designs 3.Accident Progression 4.Spent fuel pools 5.Radiological releases 6.Impact on US
- 12. Tsunami Size Was Accident Cause 3/11 15:45 at Fukushima I
- 16. Plant Designs - Fukushima Dai-ichi Unit 1 is BWR/3 Units 2-4 are BWR/4 BWR is a Boiling Water Reactor There are 52 Reactors in Japan and 104 Reactors in the USA (35 BWRs & 69 PWRs) The Fukushima I reactors began operation in the 1970s so they are all thirty - forty years old. They all are early vintage Mark I Containment Designs
- 17. Fukushima Dai-ichi Site Reactor and Fuel Specifications Fukushima Dai-ichi Tokyo Electric Power Co. Reactor Commercial Supplier Reactor No. Net MWe Reactor Model Start Unit 1 439 BWR-3 3/71 GE Unit 2 760 BWR-4 7/74 GE Unit 3 760 BWR-4 3/76 Toshiba Unit 4 760 BWR-4 10/78 Hitachi Unit 5 760 BWR-4 4/78 Toshiba Unit 6 1067 BWR-5 10/79 GE
- 18. PWR Pressurized Water Reactor
- 24. What happened? The plant was immediately shut down (scrammed) when the earthquake first hit. Off-Site power was lost. Emergency Diesel Generators (EDGs) started to provide backup electrical power to the plants backup cooling system. The backup worked. All AC power to the station was lost when the Tsunami flooded the EDGs. The diesel generators ceased functioning after approximately one hour due to Tsunami induced damage. At that point, the plant experienced a complete blackout (no AC electric power at all). Commonly called a Station Blackout.
- 25. Operating BWR
- 26. When it Started
- 29. The Tsunami Hits
- 30. What happened (cont.)? Initially the Isolation condenser (IC) for Unit 1, which uses the condensate as a heat sink, was used to remove the decay heat from the shutdown reactors. After 1 or 2 hours, the 29,000 gallons of water in the IC is hot, the condensate heat sink was not available and no heat removal was available for Unit 1. Reactor Core Isolation Cooling (RCIC) system for Units 2 & 3, which operate on steam from the reactor, were used to cool reactor core water, however, the batterysupplied control valves lost DC power after the prolonged use. DC power from batteries was consumed after approximately 34 hours. Hours passed as primary water inventory was lost and core degradation occurred (through some combination of zirconium oxidation and clad failure).
- 31. Isolation Condenser (Unit 1) and RCIC (Units 2 & 3) Were Used to Cool the Plants
- 32. RCIC Works for About 8 Hours
- 33. RCIC Stops Cooling Plants
- 35. What happened? Hydrogen in reactor building exploded causing it to collapse around the containment. The containment around the reactor and RPV were reported to be intact. Pressure in the containment drywell rose as wetwell became hotter. Hydrogen produced from zirconium oxidation was vented from the containment into the reactor building.
- 36. Fuel in Top of Core is Uncovered
- 38. What happened? Portable diesel generators were delivered to the plant site. AC power was restored allowing for a different backup pumping system to replace inventory in reactor pressure vessel (RPV). The decision was made to inject seawater into the RPV to continue to the cooling process, another backup system that was designed into the plant from inception. Radioactivity releases from operator initiated venting appear to be decreasing.
- 39. Melting of the Fuel
- 40. Release of Fission Products
- 41. Containment is Last Barrier
- 43. Unit 1 Primary Containment Pressure (D/W) & Reactor Pressure (3/11 3/16)
- 46. Decay Heat
- 47. Hydrogen Explosion Units 1 & 3
- 49. Damage to Torus Unit 2
- 50. Looking Down Units 3, 2 & 1
- 51. Units 4 & 3 Looking Down
- 54. Radiation Levels
- 56. Fukushima I Fuel Pools
- 65. Surry 1 & 2 Surry Power Station, Unit 1 &2 II PWR-DRYSUB 2,546 06/25/1968 Virginia Electric and Power Co. WEST 3LP 05/25/1972 Surry, VA S&W 12/22/1972 90 (17 miles NW of Newport News, VA) S&W 03/20/2003 050-00280 05/25/2032 www.nrc.gov/info-finder/reactor/sur1.html 94
- 66. Current Event -Surry Power Station Shuts Down After Apparent Tornado Cuts Off-site Electricity Apparent tornado damages switchyard adjacent to nuclear units Loss of Off-Site Power Emergency Diesel Generators Activated Dominion Virginia Power crews have restored off- site power to station Back-up diesel generators functioning to supplement electrical supply Units are in a safe and stable condition
- 67. US Reactors
- 68. Three Mile Island March 28, 1979
- 70. Three Mile Island History Reactor Scram: 04:00 3/28/79 Core melt and relocation: ~ 05:00 07:30 3/28/79 Hydrogen Deflagration: 13:00 3/28/79 Recirculation Cooling: Late 3/28/79 Phased Water Processing: 19791993 Containment Venting 43KCi Kr85: July 1980 Containment Entry: July 1980 Reactor Head removed and core melt found: July 1984 Start Defuel: October 1985 Shipping Spent Fuel: 19881990 Finish Defuel: Jan 1990 Evaporate ~2M gallons Processed Water: 199193 Cost: ~$1 Billion
- 71. Impact on US Reactors US has implemented B.5.b requirements in 2008 Beyond Severe Accident Guidelines Onsite high pressure portable pump Procedures and appropriate staging areas and requirements for fire hoses and equipment on site MOUs with fire local fire stations to establish the plant as a priority in case of an emergency.
- 72. Impact on US Reactor Some of the things that should be reviewed Review all external events, i.e., fire, flooding, explosions and earthquake, to ensure that there is backup emergency equipment that can support a station black out. Review training for extreme station Blackout events and procedure. Ensure that emergency batteries are qualified for worst case events for fl0od, fire, explosions and seismic. The portable high pressure pump and associated equipment that was required because of B.5.b should be housed in a structure that is qualified for worst case fire, flood, explosion and seismic events.