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Corporate Information

 
Press Release (Jul 31,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 10:00 am, July 31)
*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 5:01 am on July 31, because the amount of water injection to the 
 reactor was found to be lowered, the amount of water injection through 
 feed water system piping arrangement was adjusted to approx. 3.7 ㎥/h. 
 Water is currently injected at approx. 3.7 ㎥/h through feed water 
 system piping arrangement.
-We commenced injection of nitrogen gas into Primary Containment Vessel 
 at 1:31am on 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 fresh water by a motor driven pump powered by the 
 off-site transmission line. 
-At 5:01 am on July 31, because the amount of water injection to the 
 reactor was found to be lowered, the amount of water injection through 
 feed water system piping arrangement was adjusted to approx. 3.7 ㎥/h. 
 Water is currently injected at approx. 3.7 ㎥/h through feed water system 
 piping arrangement.
-At 8:06 pm on June 28, we started injecting nitrogen gas into the Primary 
 Containment Vessel. 
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. 8.9㎥/h through reactor feed water 
 system piping arrangement.
-At 8:01 pm on July 14, injection of nitrogen gas into the Primary 
 Containment Vessel started. 
Unit 4 (Outage due to regular inspection) 
-At approximately 6 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 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 2:45 pm on July 15, we started the operation of the original Residual 
 Heat Removal System Pump (B).
-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.
-At 7:47 pm on June 30, we started cyclic cooling of the spent fuel pool 
 in Unit 3 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 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 June 17, we started operation of water treatment of 
 accumulated water at accumulated water treatment facility. 
-At 6:00 pm on July 2, we started the circulating injection cooling to 
 inject the water, which was treated by the accumulated water treatment 
 system, to the reactors through the buffer tank.
-From 10:00 am to 5:00 pm on July 30, we transferred low level accumulated 
 water from temporary tank to Mega Float.
-From 11:00 am to 4:00 pm on July 30, we transferred accumulated water at 
 Unit 6 turbine building to the temporary tank. 
-At 11:04 am on July 30, we started transferring accumulated water at
 spent fuel common pool building to the water desalinations tank. 
-At 4:10 pm on July 30, we started transferring accumulated water at Unit 
 2 turbine building to Centralized Radiation Waste Treatment Facility. 
-At 4:13 pm on July 30, we started transferring accumulated water at Unit 
 3 turbine building to Centralized Radiation Waste Treatment Facility. 
-Approximately 3:54 am on July 31, an earthquake whose seismic center was 
 off the coast of Fukushima prefecture with magnitude 6.4 occurred, though 
 there were no particular influence to the status of activities, including 
 water injection to the reactors of Unit 1 to 3, nitrogen gas injection to 
 Primary Containment Vessels of Unit 1 to 3, operation of water treatment 
 facilities, circulating cooling of pool water using alternative cooling 
 facilities of spent fuel pool cooling and filtering system of Unit 2 and 
 3. In addition, each unit's major parameters do not show unusual figures, 
 and no injured was found. The monitoring posts located on the border of 
 the power station's premise shows figures within its normal range. 
-At 10:00 am on July 31, we started transferring low level accumulated 
 water at temporary tank to Mega Float. 
-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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