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Corporate Information

 
Press Release (Dec 28,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 3:00 pm, December 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 3:37 pm on March 25, 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 10:11 am on December 10, in addition to water injection from water
 feeding system, we started water injection from piping of core spray
 system to the reactor.
 The current water injection volume is approx. 4.3 m3/h from the reactor
 feed water system and approx. 2 m3/h from the core spray system.
-We commenced injection of nitrogen gas into Primary Containment Vessel at
 1:31 am on April 7.
-At 11:22 am on August 10, we started cyclic cooling for the water in the
 spent fuel pool by an alternative cooling equipment of the Fuel Pool
 Cooling and Filtering System. 
-On October 28, we completed installation of the cover for the Reactor
 Building in order to contain dispersion of radioactive substances.
-At 4:04 pm on November 30, we started operation to inject nitrogen into
 the reactor pressure vessel.
-At 6:00 pm on December 19, a full-scale operation of the PCV gas
 management system started.
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. 
-At 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 2:59 pm on September 14, in addition to water injection from water
 feeding system, we started water injection from piping of core spray
 system to the reactor.
 The current water injection volume is approx. 1.9 m3/h from the reactor
 feed water system and approx. 7.0 m3/h from the core spray system.
-At 5:21 pm on May 31, we started cyclic cooling for the water in the
 spent fuel pool by an alternative cooling equipment of the Fuel Pool
 Cooling and Filtering System (At 1:36 pm to 3:12 pm on December 26, we
 also started to inject hydrazine [corrosion inhibitor]).
 At 1:58 pm on December 27, in the alternative cooling system of the spent
 fuel pool of Unit 2, as the inhale pressure of the primary circulating
 pump showed the tendency of decrease, we stopped the pump in order to
 conduct flushing of the strainer on its entry side and suspended cooling
 of the spent fuel pool (the temperature of the pool at the time of the
 suspension was approx. 14.2°C). After the flushing, we are maintaining
 the inhale pressure of the primary circulating pump. Therefore, at 3:57
 pm on the same day we resumed the pump and cooling of the spent fuel pool
 (the temperature of the pool at the time of the resuming was approx.
 14.2°C).
-At 8:06 pm on June 28, we started injecting nitrogen gas into the Primary
 Containment Vessel.
-At 6:00 pm on October 28, we put the gas management system of the reactor
 containment vessel in operation.
-At 10:46 am on December 1, we started the nitrogen injection to the
 Reactor Pressure Vessel.
Unit 3 (Shut down) 
-Explosive sound and white smoke were confirmed at approximately 11:01 am
 on March 14. It was assumed to be hydrogen explosion.
-At 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 2:58 pm on September 1, we started water injection by core spray
 system in addition to water injection by the reactor feed water system
 piping arrangement. 
 The current water injection volume is approx 3 m3/h from the reactor feed
 water system and approx. 6 m3/h from the core spray system.
-At 7:47 pm on June 30, we started cyclic cooling for the water in the
 spent fuel pool by an alternative cooling equipment of the Fuel Pool
 Cooling and Filtering System.
-At 8:01 pm on July 14, injection of nitrogen gas into the Primary
 Containment Vessel started. 
-At 4:26 pm on November 30, we started operation to inject nitrogen into
 the reactor pressure vessel.
Unit 4 (Outage due to regular inspection) 
-At around 6 am on March 15, we confirmed the explosive sound and the
 sustained damage around the 5th floor rooftop area of Reactor Building.
-At 12:44 pm on July 31, we started cyclic cooling for the water in the
 spent fuel pool by an alternative cooling equipment of the Fuel Pool
 Cooling and Filtering System. (In addition, at 1:28 pm on December 28, we 
 started injection of hydrazine to spent fuel pool of Unit 4 through the 
 circulating cooling system.) 
-At 10:58 am on November 29, in order to decrease more salinity, we
 installed Ion exchange equipment and started the operation of such
 equipment.
-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 5:00 am on March 19, we started the Residual Heat Removal System Pump
 in order to cool the spent fuel pool.
-At 2:45 pm on July 15, we started the operation of the original Residual
 Heat Removal System (System B) by its original seawater pump.
-At 10:11 am on December 22, since we finished the recovery work of
 seawater pump (System B) of equipment water cooling system, we made a
 trial run. At 11:25 am on the same day, we confirmed no abnormalities and
 restarted the operation.
-At this moment, 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 2:33 pm on September 15, we started separately cooling the reactor
 through the Residual Heat Removal System and the spent fuel pool through
 Equipment Cooling Water System and Fuel Pool Cooling System.
-At this moment, we do not think there is any reactor coolant leakage
 inside PCV.
Others 
-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 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.
-At 7:41 pm on August 19, we started treatment of accumulated water by
 parallel operation of one line from the cesium adsorption instrument to
 the decontamination instrument and the other treatment line of the cesium
 adsorption instrument No.2.
-At 2:06 pm on October 7, we started to spray purified accumulated water
 brought from Unit 5 and 6 continually in order to prevent dust scattering
 and potential fire outbreaks from the cut down trees.
-On October 28, we started installation of the water proof wall at the sea
 side, in front of the existing shore protection, Units 1-4, in order to
 contain marine pollution by underground water.
-At 12:25 pm on December 13, we started the re-circulating operation of
 desalination facility (reverse osmosis membrane type) for the purpose of
 suppression of condensed water after desalination treatment.
-Since December 22, one of the atmospheric temperatures of Unit 1 Primary
 Containment Vessel (PCV) monitored by the Containment Atmospheric
 Monitoring System had risen (the atmospheric temperature of the PCV on
 December 22 was approx. 38°C, at 7 pm on December 27 was approx. 49°C).
 The other temperatures had not risen, so we conducted a survey from 9 am
 to 10 am on December 28, and we confirmed that there are no problems.
 From 11:00am to 12:15pm on the same date, to identify cause with 
 monitoring, we adjusted the volume of Nitrogen injection, from approx. 
 8 m2/h to approx.18 m2/h, and emission of the gas management system, from 
 approx. 23 m2/h to approx.30 m2/h, as of before December 22. 
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