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Corporate Information

 
Press Release (May 28,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 3:00 pm, May 28)
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 feed water system was initiated.
-From 3:37 pm on March 25, we started injecting freshwater. We are now 
 injecting freshwater by a motor driven pump powered by the off-site 
 transmission line at 6 m3/h.
-As it is suspected that hydrogen gas is accumulated inside Primary 
 Containment Vessel, we commenced the valve opening operation concerning 
 injection of nitrogen gas into the primary containment vessel at 10:30 pm 
 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 7 m3/h. 
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 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. 
-At 8:42 pm on May 27th, we changed the rate of water injection to the 
 reactor of unit3 through the fire extinction system piping arrangement 
 from approximately 2 m3/h to approximately 1 m3/h.
-The current rate of water injection is approximately 1 m3/h through the 
 fire extinction system piping arrangement and approximately 13.5 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 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 cold shutdown. 
-At this moment, we do not consider any reactor coolant leakage inside the 
 primary containment vessel 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 cold shutdown. 
-At this moment, we do not consider any reactor coolant leakage inside the 
 primary containment vessel happened. 
Operation for cooling the spent fuel pools 
-At 5:05 pm on May 27th, we started to spray water to the spent fuel pool 
 of Unit 4 by the concrete pumping vehicle (We added hydrazine from 5:24pm 
 to 6:53pm). We finished spraying at 8:00pm on the same day.
-At 1:28 Pm on May 28th, we started freshwater injection to the spent fuel 
 pool of Unit 3 by a temporary motor driven pump (we also injected 
 hydrazine from 1:42 Pm to 2:40 pm). 
-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.
 Since May 27th, we have started spraying dust inhibitor to Unit 1's 
 turbine building. We will implement spraying the dust inhibitor to other 
 buildings including Unit 1 to 4's turbine buildings as well as reactor 
 buildings one by one.
-Since 10:08 am on April 19, we had been transferring high level 
 radioactive wastewater from the vertical shaft near the turbine building 
 of Unit 2 to the Centralized Radiation Waste Treatment Facility. At 4:01 
 pm on May 26, a transferring operation was stopped.
-At 2:00 pm on May 1, we started transferring the accumulated water in 
 turbine building of Unit 6 to temporary tanks.
-At 11:00 am on May 10, we started transferring the accumulated water from 
 the underground level of reactor building to the radiation waste 
 treatment facility of Unit 6.
-Since 6:04 pm on May 17, we had been transferring high level radioactive 
 waste water from the underground level of the turbine building of Unit 3 
 to the Centralized Radiation Waste Treatment Facility, but the transfer 
 was suspended due to an inspection on transmission lines and buildings at 
 9:10 am, on May 25.
-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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