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Corporate Information

 
Press Release (Jun 21,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 10:00 am, June 21)
*No updates in this issue 
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 powered by the off-site transmission line. We are now
  injecting freshwater by a motor driven pump powered by the off-site
  transmission line. Current injected water amount is approx. 4.5 m3/h
  through feed water system.
- 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. 
  The current rate of water injection is approx. 5 m3/h through the 
  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.
  The current rate of water injection is approx. 11.5 m3/h through the
  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 2:00 pm on May 1, we started transferring accumulated water in the
  turbine building of Unit 6 to temporary tanks.
- 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 12:42 pm on June 11, we started to operate local exhausters in order
  to improve inside environment of Unit 2 Reactor Building. At 8:51 pm on
  June 19, we slightly opened the airlock of the reactor building, and at
  5:00 am on June 20 we fully opened it. At 2:30 pm on the same day we
  opened the truck bay door of the reactor building. We confirmed a
  monitored result of dose rate in the air and confirmed that there was no
  external impact.
- 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.
- At 2:20 pm on June17, we started transferring accumulated water in the
  vertical shaft (trench) of the turbine building of Unit 2 to the
  condenser in the turbine building of Unit 1. However, at 2:59 pm we
  stopped the operation of the transfer pump since water flux was not
  observed. The transfer pump that we had confirmed did not properly work
  was switched to other ones and we resumed transfer of accumulated water
  at 1:37 pm on June 20.
- 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.
- At 9:49 am on June 20, we started fresh water injection to the reactor
  wells and pools for temporary storage of equipments of Unit 4 and Unit 5,
  in order to improve the working environment (to reduce radiation dose)
  on the 5th floor of the reactor building of Unit 4 and Unit 5.
- 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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