fukushima daiichi nuclear power station accident april19 2011
DESCRIPTION
Presentation of Fukushima II Accident through April 22, 2011TRANSCRIPT
By
Joseph 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 DaiichiAccident
1. What Happened?
2.Plant Designs
3.Accident Progression
4.Spent fuel pools
5.Radiological releases
6.Impact on US
What Happened?
Tsunami Size Was Accident Cause 3/11 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 – Tokyo Electric Power Co.
Reactor No. Net MWe Reactor ModelCommercial
Start
Reactor
Supplier
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
Fukushima Dai-ichi Site Reactor and Fuel Specifications
PWR – Pressurized Water Reactor
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 plant’s 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”.
Operating BWR
When it Started
Containment Isolation
The Tsunami Hits
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 battery‐supplied 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).
Isolation Condenser (Unit 1) and RCIC (Units 2 & 3) Were Used to Cool the Plants
RCIC Works for About 8 Hours
RCIC Stops Cooling Plants
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.
Fuel in Top of Core is Uncovered
Zr-Water Begins at
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.
Melting of the Fuel
Release of Fission Products
Containment is Last Barrier
Venting the Containment
Unit 1 Primary Containment Pressure (D/W) & Reactor Pressure (3/11 – 3/16)
Decay Heat
Hydrogen Explosion Units 1 & 3
Damage to Torus Unit 2
Looking Down Units 3, 2 & 1
Units 4 & 3 Looking Down
Radiation Levels
Fukushima I Fuel Pools
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 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
US Reactors
Three Mile IslandMarch 28, 1979
TMI Core ConfigurationEvening 3/28/1979
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.