fukushima daiichi nuclear power station accident april19 2011
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DESCRIPTIONPresentation of Fukushima II Accident through April 22, 2011
- 1. ByJoseph 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 Accident1. What Happened?2.Plant Designs3.Accident Progression4.Spent fuel pools5.Radiological releases6.Impact on US
- 5. What Happened?
- 6. Tsunami Size Was Accident Cause3/11 15:45 at Fukushima I
- 7. 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
- 8. 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
- 9. PWR Pressurized Water Reactor
- 10. What happened?The plant was immediately shut down (scrammed)when the earthquake first hit. Off-Site power was lost.Emergency Diesel Generators (EDGs) started toprovide backup electrical power to the plants backupcooling system. The backup worked.All AC power to the station was lost when the Tsunamiflooded the EDGs.The diesel generators ceased functioning afterapproximately one hour due to Tsunami induceddamage.At that point, the plant experienced a completeblackout (no AC electric power at all). Commonlycalled a Station Blackout.
- 11. Operating BWR
- 12. When it Started
- 13. Containment Isolation
- 14. The Tsunami Hits
- 15. What happened (cont.)?Initially the Isolation condenser (IC) for Unit 1, which uses thecondensate as a heat sink, was used to remove the decay heatfrom the shutdown reactors. After 1 or 2 hours, the 29,000gallons of water in the IC is hot, the condensate heat sink wasnot 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 coolreactor core water, however, the batterysupplied control valveslost DC power after the prolonged use.DC power from batteries was consumed after approximately34 hours.Hours passed as primary water inventory was lost and coredegradation occurred (through some combination ofzirconium oxidation and clad failure).
- 16. Isolation Condenser (Unit 1) and RCIC (Units 2 &3) Were Used to Cool the Plants
- 17. RCIC Works for About 8 Hours
- 18. RCIC Stops Cooling Plants
- 19. What happened?Hydrogen in reactor building exploded causing it tocollapse around the containment.The containment around the reactor and RPV werereported to be intact.Pressure in the containment drywell rose as wetwellbecame hotter.Hydrogen produced from zirconium oxidation wasvented from the containment into the reactor building.
- 20. Fuel in Top of Core is Uncovered
- 21. Zr-Water Begins at
- 22. What happened?Portable diesel generators were delivered to the plantsite.AC power was restored allowing for a different backuppumping system to replace inventory in reactor pressurevessel (RPV).The decision was made to inject seawater into the RPVto continue to the cooling process, another backupsystem that was designed into the plant from inception.Radioactivity releases from operator initiated ventingappear to be decreasing.
- 23. Melting of the Fuel
- 24. Release of Fission Products
- 25. Containment is Last Barrier
- 26. Venting the Containment
- 27. Unit 1 Primary Containment Pressure(D/W) & Reactor Pressure (3/11 3/16)
- 28. Decay Heat
- 29. Hydrogen Explosion Units 1 & 3
- 30. Damage to Torus Unit 2
- 31. Looking Down Units 3, 2 & 1
- 32. Units 4 & 3 Looking Down
- 33. Radiation Levels
- 34. Fukushima I Fuel Pools
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