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Corporate Information

 
Press Release (Aug 10,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 10:00 pm, Aug 10)
 
*New items 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.
 Water is currently injected at approx. 3.8 ㎥/h through reactor feed 
 water system piping arrangement.
-We commenced injection of nitrogen gas into Primary Containment Vessel 
 at 1:31am on April 7.
-At 9:00 am on August 10, we started to assemble steel frame for the 
 Reactor Building Cover. 
 
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.
 Water is currently injected at approx. 3.8 ㎥/h through reactor 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 don't think there is any reactor coolant leakage 
 inside the primary containment vessel. 
 
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 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 time, we don't think there is any reactor coolant leakage inside 
 the primary containment vessel. 
 
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 
 of Unit 6 to cool down Spent Fuel Pool.
-At 7:27 pm on March 20, the reactor achieved cold shutdown. 
-At this time, we don't think there is any reactor coolant leakage inside 
 the primary containment vessel.
-From 9:30 am to 1:40 pm on August 9, we conducted plumbing between 
 temporary pump and residual heat removal system pump (A) to enforce the 
 connection method. We stopped the power source of residual heat removal 
 system pump (B) during this work. Even though cooling of a reactor and a 
 spent fuel pool were temporarily suspended, there are no safety issues 
 regarding this. 
 
Operation for cooling the Spent Fuel Pools 
-At 5:21 pm on May 31, we started cyclic cooling of Spent Fuel Pool of 
 Unit 2 by using alternative cooling system of the Pool's cooling and 
 filtering system.
-At 7:47 pm on June 30, we started cyclic cooling of Spent Fuel Pool of 
 Unit 3 by using alternative cooling system of the Pool's cooling and 
 filtering system.
-At 0:44 am on July 31, we started cyclic cooling of Spent Fuel Pool of 
 Unit 4 by using alternative cooling system of the Pool's cooling and 
 filtering system. 
 
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 around 10 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 8:00 pm on June 17, we started operation of Water Treatment Facility 
 against the accumulated water. 
-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 7:09 am on August 4 to 4:56 pm on August 9, we transferred 
 accumulated water at Unit 2 turbine building to Centralized Radiation 
 Waste Treatment Facility.
-At 8:42 am on August 5, we started transferring accumulated water at 
 Unit 3 turbine building to Centralized Radiation Waste Treatment Facility.
-At 4:11 pm on August 7, we completed commissioning of additional two 
 evaporative condensation facilities to the water treatment facility to 
 make freshwater from condensed seawater from desalination facility. We 
 put those additional facilities to full-scale operation.
-At 10:00 am on August 9, we started transferring low level accumulated 
 water from outdoor temporary tanks to Mega Float. However, at 10:12 am, 
 since leakage was confirmed from the transferring pipes cabled at outside, 
 we stopped transferring. Thereafter, such pipes were replaced and at 1:35 
 pm, we resumed transferring.
-From 10:39 am to 11:13 am on August 9, we conducted gas sampling in the 
 Primary Containment Vessel of Unit 2. 
-At 11:00 am on August 9, we started transferring of accumulated water 
 from inside the Unit 6 turbine building to temporary tanks. 
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