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Press Release (May 15,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 3:00 pm, May 15)
 
*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 nuclear 
  reactor through the feed water system was initiated.
- From 3:37 pm on March 25, we started injecting freshwater and are now 
  injecting fresh water by a motor driven pump powered by the off-site 
  transmission line.
- As it is suspected that hydrogen gas is accumulated inside reactor 
  containment vessel, we commenced the valve opening operation concerning 
  injection of nitrogen gas into the reactor container vessel at 10:30 pm 
  April 6th and commenced injection at 1:31am April 7.
- At 10:01 am on May 6, in order to make nuclear reactor flooded to the 
  top of Fuel range, we have increased the amount of injecting freshwater 
  from approximately 6m3/h to approximately 8m3/h. 
- At 1:28 pm on May 15, we have increased the amount of freshwater 
  injected into the reactor from approximately 8m3/h to approximately 
  10m3/h so that we can monitor the trend shift of parameters of the 
  Reactor Pressure Vessel as well as the Primary Containment Vessel, the 
  shift which would be resulted from the increase of the amount of 
  injected freshwater.
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 fresh water by a motor driven pump powered 
  by the off-site transmission line.
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.
- At 4:53 pm on May 12, as a part of work to switch the water injection 
  line to the nuclear reactor from the fire extinction system to the 
  reactor feed water system, we started water injection through the 
  reactor feed water system in addition to through the fire extinction 
  system. 
  The current rate of water injection is approximately 6 m3/h through the 
  fire extinction system piping arrangement and approximately 9 m3/h 
  through the reactor feed water system piping arrangement .
- At 2:33 pm on May 15, we started injecting boric acid through the fire 
  extinction system.
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 the 
  Nuclear Reactor Building.
- At this moment, we do not consider any reactor coolant leakage inside 
  the reactor happened. 
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 reactor cold shutdown. 
- At this moment, we do not consider any reactor coolant leakage inside 
  the reactor happened.
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 reactor cold shutdown. 
- At this moment, we do not consider any reactor coolant leakage inside 
  the reactor happened.
Operation for cooling the spent fuel pools 
- At 3:07 pm on May 14, we started spraying water into the spent fuel pool 
  of Unit 1 with the concrete pumping vehicle. We stopped it at 3:18 pm on 
  the same day due to strong winds.
- We will continuously conduct further water spray depending on the 
  conditions of spent fuel pools, if needed.
Injured etc 
- At about 6:50 am on May14, a worker of a sub-contractor became a bad 
  health during a carrying work for drainage treatment system in the 
  Centralized Environment Facility. He was carried to hospital. We 
  received a notice from the hospital on phone that the worker died at 
  9:33 am on May 14.
Others 
- At 1:30 pm on April 26, we have started spraying the dust inhibitor 
  inside the building.
- At 10:08 am on April 19, we started transfer of high level radioactive 
  wastewater from the vertical shaft near the turbine building of Unit 2 
  to the Centralized Radiation Waste Treatment Facility.
- At 2:00 pm on May 1, we have started transferring the accumulated water 
  in turbine building of Unit 6 to temporary tanks.
- At 11:00 am on May 10, we have started transferring the accumulated 
  groundwater inside the reactor building to the radiation waste treatment 
  facility in Unit 6.
- 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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