Fukushima Daiichi Nuclear Power Station Accident April19 2011
ByJoseph S. Miller EDA, Inc
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.
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
The Fukushima Daiichi Accident1. What Happened?2.Plant Designs3.Accident Progression4.Spent fuel pools5.Radiological releases6.Impact on US
Tsunami Size Was Accident Cause3/11 15:45 at Fukushima I
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 1970’s so they are all thirty - forty years old. They all are early vintage Mark I Containment Designs
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
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 plant’s 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”.
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 battery‐supplied 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).
Isolation Condenser (Unit 1) and RCIC (Units 2 &3) Were Used to Cool the Plants
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.
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.
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
Current Event -Surry Power Station Shuts DownAfter 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
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: 1979‐1993 Containment Venting 43KCi Kr‐85: July 1980 Containment Entry: July 1980 Reactor Head removed and core melt found: July 1984 Start Defuel: October 1985 Shipping Spent Fuel: 1988‐1990 Finish Defuel: Jan 1990 Evaporate ~2M gallons Processed Water: 1991‐93 Cost: ~$1 Billion
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.
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.