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Corporate Information

 
Press Release (Jun 24,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 10:00 am, June 24)
 
*Updates are underlined 
All 6 units of Fukushima Daiichi Nuclear Power Station have been shut down. 
Unit 1 (Shut down) 
- Explosive sound and white smoke were confirmed after the big quake 
  occurred at 3:36 pm on March 12. It was assumed to be hydrogen explosion.
- At approximately 2:30 am on March 23, seawater injection to the reactor 
  through the reactor feed water system was initiated.
- From 3:37 pm on March 25, we started injecting freshwater by a motor 
  driven pump which is now powered by the off-site transmission line. At 
  10:02 am on June 22, we changed the rate of water injection to the 
  reactor from approx. 4.0 m3/h to approx. 3.5m3/h through reactor feed 
  water system piping arrangement. Water is currently injected at approx. 
  3.5m3/h through reactor feed water system piping arrangement.
  As it was suspected that hydrogen gas had been accumulated inside Primary 
  Containment Vessel, in order to prevent increase in density of oxygen, 
  we commenced the valve opening operation concerning injection of nitrogen 
  gas into the primary containment vessel at 10:30 pm on April 6 and 
  commenced injection at 1:31am April 7. 
Unit 2 (Shut down) 
- At approximately 6:00 am on March 15, an abnormal noise began emanating 
  from nearby Pressure Suppression Chamber and the pressure within the 
  chamber decreased. 
- From 10:10 am on March 26, we started injecting freshwater to the reactor 
  and are now injecting freshwater by a motor driven pump powered by the 
  off-site transmission line. 
  At 6:27 pm on June 23, we changed the water injection line so that we can 
  inject water to Unit 1 and 2 by the motor driven pump for Unit 1 and 
  stopped the motor driven pump Unit 2. 
  Water is currently injected at approx. 3.5m3/h through reactor feed water 
  system piping arrangement. 
Unit 3 (Shut down) 
- Explosive sound and white smoke were confirmed at approximately 11:01am 
  on March 14. It was assumed to be hydrogen explosion.
- From 6:02 pm on March 25, we started injecting fresh water to the reactor 
  and are now injecting fresh water by a motor driven pump powered by the 
  off-site transmission line.
  Water is currently injected at approx. 9.5 m3/h through reactor feed 
  water system piping arrangement. 
Unit 4 (Outage due to regular inspection) 
- At approximately 6:00 am on March 15, we confirmed the explosive sound 
  and the sustained damage around the 5th floor rooftop area of Reactor 
  Building.
- At this moment, we do not consider any reactor coolant leakage inside 
  the primary containment vessel has occurred. 
Unit 5 (Outage due to regular inspection) 
- Sufficient level of reactor coolant to ensure safety is maintained.
- At 5:00 am on March 19, we started the Residual Heat Removal System Pump 
  (C) in order to cool the spent fuel pool.
- At 2:30 pm on March 20, the reactor achieved cold shutdown. 
- At this moment, we do not consider any reactor coolant leakage inside 
  the primary containment vessel has occurred. 
Unit 6 (Outage due to regular inspection) 
- Sufficient level of reactor coolant to ensure safety is maintained.
- At 10:14 pm on March 19, we started the Residual Heat Removal System Pump 
  (B) of Unit 6 in order to cool the spent fuel pool.
- At 7:27 pm on March 20, the reactor achieved cold shutdown. 
- At this moment, we do not consider any reactor coolant leakage inside 
  the primary containment vessel has occurred. 
Operation for cooling the spent fuel pools 
- At 5:21 pm on May 31, we started cyclic cooling of the spent fuel pool 
  in Unit 2 using alternative cooling system for fuel pool cooling and 
  filtering system. 
- We will continuously conduct further water spray depending on the 
  conditions of spent fuel pools, if needed. 
Others 
- At 1:30 pm on April 26, we started spraying the dust inhibitor inside 
  the site. 
- At 11:00 am on May 10, we started transferring accumulated water from 
  the underground level of reactor building to the radiation waste treatment 
  facility of Unit 6.
- At approximately 10:00 am on June 13, we started the operation of the 
  circulating seawater purification facility installed at the screen area 
  of Unit 2 and 3.
- From 8:00 pm on June17, we started operation of water treatment of 
  accumulated water at accumulated water treatment facility. At 12:54 am 
  on June18, we stopped operation of the facility temporarily due to the 
  radiation dose at surface level measured up to the basis of exchange 
  filter of Cesium adsorption Instruments. Afterwards, we exchanged filter 
  of Cesium absorption Instruments, experimented water flowing and conducted 
  flashing the facility. From 12:43 am on June 23, the operation of 
  accumulated water treatment system.
- At 3:32 pm on June 21, we started transferring accumulated water in 
  turbine building of Unit 3 to central waste treatment facility building.
- At 9:56 am on June 22, we started transferring accumulated water in 
  turbine building of Unit 2 to central waste treatment facility building.
- From 9:32 am to 3:29 pm on June 23, we injected fresh water to reactor 
  well and dry separator pit of Unit 4 for the purpose of environmental 
  improvement (decreasing dose) at 5th floor of reactor building of Unit 4.
- At approximately 7:00 am on June 24, an unmanned helicopter collecting 
  dust from the open part of the reactor building of Unit 2 made an 
  emergency landing on the top of the reactor building of Unit 2. While 
  the details are under investigation, nobody got injured. 
- We will continue to take all measures to ensure the safety and to 
  continue monitoring the surrounding environment around the power station. 
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