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Corporate Information

 
Press Release (Apr 10,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 11:00 am, April 10)
*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 12th. It was assumed to be hydrogen 
 explosion.
-At approximately 2:30 am on March 23rd, seawater injection to the nuclear 
 reactor through the feed water system was initiated.
-From 3:37 pm on March 25th, we started injecting freshwater.
-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 7th. 
Unit 2(Shut down) 
-At approximately 6:00 am on March 15th, an abnormal noise began emanating 
 from nearby Pressure Suppression Chamber and the pressure within the 
 chamber decreased. 
-From 10:10 am on March 26th, 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 
 March 14th. It was assumed to be hydrogen explosion.
-From 6:02 pm on March 25th, 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. 
Unit 4 (outage due to regular inspection) 
-At approximately 6:00 am on March 15th, 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, March 19th, we started the Residual Heat Removal System Pump 
 (C) in order to cool the spent fuel pool.
-At 2:30 pm, March 20th, the reactor achieved reactor cold shutdown. At 
 around 5:24 pm on March 23rd, when we switched the temporary Residual 
 Heat Removal System Seawater Pump, it has stopped automatically. At 
 around 4:14 pm, March 24th we replaced the pump, and restarted cooling of 
 reactor at around 4:35 pm.
-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, March 19th, we started the Residual Heat Removal System Pump 
 (B) of Unit 6 in order to cool the spent fuel pool.
-At 7:27 pm, March 20th, the reactor achieved reactor cold shutdown.
-In relation to the two seawater side pumps of the Residual Heat Removal 
 System, we switched the power source from temporary to permanent at 3:38 
 pm and 3:42 pm, Mar 25 respectively.
-At this moment, we do not consider any reactor coolant leakage inside the 
 reactor happened. 
Operation for cooling the spent fuel pools 
-From 5:07 pm to 7:24 pm on April 9th, spraying water to Unit 4 by 
 concrete pump vehicle was conducted.
-At 10:37 am on April 10th, the injection of fresh water into Unit 2 with 
 a temporary motor driven pump was initiated. 
-We will conduct further water spray depending on the conditions of spent 
 fuel pools, if needed. 
Draining water from underground floor of turbine buildings 
-From 1:55 pm on April 3rd to 9:30 am on April 10th, at Unit 1, 
 transferring water from a condenser to condensate storage tank was 
 conducted. 
Others 
-We measured radioactive materials (iodine etc.) inside of the nuclear 
 power station area (outdoor) by monitoring car and confirmed that 
 radioactive materials level is getting higher than ordinary level. As 
 listed below, we have determined that specific incidents stipulated in 
 article 15, clause 1 of Act on Special Measures Concerning Nuclear 
 Emergency Preparedness (Abnormal increase in radiation dose measured at 
 site boundary) have occurred.
 ·Determined at 4:17 pm Mar 12th (Around Monitoring Post 4 )
 ·Determined at 8:56 am Mar 13th (Around Monitoring Post 4 )
 ·Determined at 2:15 pm Mar 13th (Around Monitoring Post 4 )
 ·Determined at 3:50 am Mar 14th (Around Monitoring Post 6 )
 ·Determined at 4:15 am Mar 14th (Around Monitoring Post 2 ) 
 ·Determined at 9:27 am Mar 14th (Around Monitoring Post 3 ) 
 ·Determined at 9:37 pm Mar 14th (Around main entrance ) 
 ·Determined at 6:51 am Mar 15th (Around main entrance ) 
 ·Determined at 8:11 am Mar 15th (Around main entrance ) 
 ·Determined at 4:17 pm Mar 15th (Around main entrance ) 
 ·Determined at 11:05 pm Mar 15th (Around main entrance )
 ·Determined at 8:58 am Mar 19th (Around MP5)
 Hereafter, if the measured figure fluctuates and goes above and below 500 
 micro Sv/h, we deem that as the continuous same event and will not regard 
 that as a new specific incidents stipulated in article 15, clause 1 of 
 the Act on Special Measures Concerning Nuclear Emergency Preparedness 
 (Abnormal increase in radiation dose measured at site boundary) has 
 occurred. In the interim, if we measure a manifestly abnormal figure and 
 it is evident that the event is not the continuous same event, we will 
 determine and notify.
-The national government has instructed evacuation for those local 
 residents within 20km radius of the periphery and evacuation to inside 
 for those residents from 20km to 30km radius of the periphery, because it 
 is possible that radioactive materials are discharged.
-In total 12 fire engines are lent for the water spraying to the spent 
 fuel pools and water injection to the nuclear reactors by various 
 regional fire departments* as well as Tokyo Fire Department. Also, 
 instruction regarding the setting and operation of large scale 
 decontamination system was provided by Niigata City Fire Headquarter and 
 Hamamatsu City Fire Headquarter.
 *:Koriyama Fire Department, Iwaki Fire Brigade Headquarters, Fire 
   Headquarters of Sukagawa District Wide Area Fire-fighting Association, 
   Yonezawa City Fire Headquarters, Utsunomiya City Fire Headquarters, 
   Fire Headquarters of Aizu-Wakamatsu wide area municipal association, 
   Saitama City Fire Bureau, and Niigata City Fire Bureau.
-At around 11:35 am April 1st, a worker fell into the sea when he got into 
 a barge of the U.S. Forces to repair a hose of the ship. The worker was 
 rescued immediately, and was not injured and not contaminated. The worker 
 will be checked using the whole-body counter to ensure his health.
-From April 2nd, we began to transfer the radioactive water we collected 
 from the Central Environmental Facility to the Unit 4 turbine building. 
 On April 4th, water level of the pit in the trench of Unit 3 increased by 
 15cm from previous day. Pathway of water flow is unknown. We can not deny 
 the possibility that water in the turbine building of Unit 4 flows into 
 the trench of Unit 3. So, we stopped transferring water to the Unit 4 
 turbine building to make assurance. Present water level of the pit in the 
 trench of Unit 3 is not changed from the time we stopped transferring, 
 and is being stable.
-As a countermeasure against outflow of radioactive water into the sea 
 near the cooling water intake at Unit 2 of Fukushima Daiichi Nuclear 
 Power Station, we have injected coagulant into the pit from April 5th and 
 we have observed stoppage of spilling of water from the crack on the 
 concrete lateral of the pit at 5:38 am, April 6th. We have put 6,000 
 litters of coagulant into the breakage and surrounding ground after 
 investigation of the leakage route by putting tracer into the 9 holes 
 drilled around electrical conduit and the pit. On April 6th, we installed 
 rubber boards and jigs as a countermeasure against the outflow from the 
 intake. We will further investigate if there is any other leakage.
-From 7:03 pm, April 4, we started to discharge to the sea approximately 
 ten thousand tons of the accumulated low level radioactive water in the 
 Central Radioactive Waste Disposal Facility. From 9:00 pm on April 4 to 
 6:52 pm on April 9, we conducted discharging a total of 1,500 tons of the
 low level radioactive subsurface water stored in the sub drain pits of 
 Unit 5 and 6. The amount of discharged water was approximately 1,320 tons. 
-From 3:00 pm to 4:30 pm, April 5th, in order to prevent diffusion of 
 radioactive contaminated water out from the site port facility to 
 breakwater area which is south to the power station, we began repair of 
 breakwater by founding the large sandbag around it to replace damaged 
 steel water bar. We will continue the operation to prevent diffusion.
-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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