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Corporate Information

 
Press Release (Jan 02,2012)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 10:00 am, January 2)
*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, 2011. It was assumed to be hydrogen
 explosion.
-At 3:37 pm on March 25, 2011, 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, 2011, in addition to water injection from
 water feeding system, we started water injection from piping of core
 spray system to the reactor.
 Current water injection volume is approx. 4.8 m3/h from the reactor feed
 water system and approx. 2 m3/h from the core spray system.
-At 1:31 am on April 7, 2011, we commenced injection of nitrogen gas into
 Primary Containment Vessel.
-At 11:22 am on August 10, 2011, 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, 2011, 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, 2011, we started operation to inject nitrogen
 into the reactor pressure vessel.
-At 6:00 pm on December 19, 2011, a full-scale operation of the PCV gas
 management system started. 
Unit 2 (Shut down) 
-At approximately 6:00 am on March 15, 2011, an abnormal noise began
 emanating from nearby Pressure Suppression Chamber and the pressure
 within the chamber decreased. 
-At 10:10 am on March 26, 2011, 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, 2011, in addition to water injection from
 water feeding system, we started water injection from piping of core
 spray system to the reactor.
 Current water injection amount is approx.2 m3/h in feed water system and
 approx.7 m3/h in corer spray system
-At 5:21 pm on May 31, 2011, 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 8:06 pm on June 28, 2011, we started injecting nitrogen gas into the
 Primary Containment Vessel.
-At 6:00 pm on October 28, 2011, we put the gas management system of the
 reactor containment vessel in operation.
-At 10:46 am on December 1, 2011, 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, 2011. It was assumed to be hydrogen explosion.
-At 6:02 pm on March 25, 2011, 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, 2011, 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 2.9 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, 2011, 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.
 Since inlet pressure of the primary circulation pump in the alternative
 cooling system of the spent fuel pool frequently tended to decrease due
 to the effect of clogging of the inlet strainer of the pump, the pump was
 stopped at each time in order to flush the strainer. However, since this
 tendency is supposed to continue and the temperature of the spent fuel
 pool is sufficiently low, which is approx. 13.0°C, and there is enough
 margin from the operational limit value (upper limit) by the safety
 regulation, which is 65.0°C, we determined to stop the pump by January 4
 of 2012 and temporary stop the cooling of spent fuel pool, considering
 the exposure dose during the flushing.
 At 4:54 pm on December 30, 2011, the pump was stopped. (Temperature of
 the spent fuel pool was approx. 13.3°C at the time of shutdown.) It is
 valuated that the temperature rise of the spent fuel pool due to the
 shutdown of the pump is approx. 5 to 6 degrees for a day. And it is
 planned that this pump operates for one time in a day to check the
 temperature of the spent fuel pool during this temporary operation, since
 December 31, 2011.
-At 8:01 pm on July 14, 2011, injection of nitrogen gas into the Primary
 Containment Vessel started. 
-At 4:26 pm on November 30, 2011, 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, 2011, 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, 2011, 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 10:58 am on November 29, 2011, in order to decrease more salinity, we
 installed Ion exchange equipment and started the operation of such
 equipment.
 At approx. 5:30 pm on January 1, 2012, we observed approx. 240 mm 
 decrease in the water level of the skimmer surge tank*1 of Unit 4 spent 
 fuel pool in the three hours between 2:00 pm to 5:00 pm (According to the 
 operation record so far, there had been an approx. 50 mm decrease.). As a 
 result of the site investigation later, we did not observe any leakage 
 around the Unit 4 reactor building, connecting points of primary system 
 pipes of Unit 4 spent fuel pool alternative cooling system, or its 
 installation space. The water temperature of Unit 4 spent fuel pool as of 
 5:00 pm on January 1 is 23°C (22°C as of 5:00 am on January 2). The spent 
 fuel pool alternative cooling system is still in operation and there is 
 no problem in cooling the reactor. Though the water level of the spent 
 fuel pool is kept stable without any problem, the water level in the 
 skimmer surge tank continues decreasing. Therefore, from 10:27 pm to 
 11:13 pm on January 1, we filled water in the skimmer surge tank. At 
 present, the water level in the skimmer surge tank keeps decreasing 
 approx. 90mm/hour. We will strengthen surveillance on observation of the 
 water level in the skimmer surge tank, increasing the frequency to once 
 in an hour from once in three hours. At the same time, we will continue 
 examination of the causes of the decrease in the water level, such as 
 site investigations based on such possibilities as the water may flow 
 into the reactor well*2 from the spent fuel pool. 
 At present, no leakage is observed outside the building. No significant 
 change is observed in the water level of the accumulated water in the 
 building. 
*1 The tank installed in order to receive the water overflows from the 
   spent fuel pool. The water in the spent fuel pool is overflowed into 
   the skimmer surge tank in order to cool the fuel assembly and remove  
   impurities in the water. The water returns to the spent fuel pool after 
   passing through the heat exchanger and the filter. 
*2 The reactor well is the space which contains the reactor pressure 
   vessel and the lid of the reactor containment vessel. During the 
   periodical inspections, the space filled with water and the fuel is  
   changed. 
-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, 2011, we started the Residual Heat Removal System
 Pump in order to cool the spent fuel pool.
-At 2:45 pm on July 15, 2011, 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, 2011, 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, 2011, we started the Residual Heat Removal
 System Pump of Unit 6 to cool down Spent Fuel Pool.
-At 2:33 pm on September 15, 2011, 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, 2011, 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, 2011, 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, 2011, 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, 2011, 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, 2011, 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, 2011, 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, 2011, the atmospheric temperatures at point C 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 checking the reliability of the meters 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 day, we adjusted the volume of Nitrogen injection,
 from approx. 8 m3/h to approx.18 m3/h, and emission of the gas
 management system, from approx. 23 m3/h to approx.30 m3/h, in order to
 identify the cause by monitoring the system with the same injection and
 emission volume as before December 22. The temperature went up to approx.
 54.6°C at 6:00 pm on December 28 at its maximum and fell to approx.
 43.5°C at 5:00 am on January 2, 2012. Temperatures at other two points
 also indicated slight increases but are currently in the stable status.
  Point D: (Maximum) approx. 35.8°C at 5:00 pm on December 29, 2011 → 
  approx. 32.7°C at 5:00 am on January 2, 2012.
  Point E: (Maximum) approx. 40.0°C at 5:00 pm on December 29, 2011 → 
  approx. 35.8°C at 5:00 am on January 2, 2012.
 We will continuously conduct the survey for the cause of temperature
 increase and surveillance of the plant.
-At 3:22 pm on December 28, 2011, we started to transfer accumulated water
 from the basement of turbine building of Unit 2 to the Centralized
 Radiation Waste Treatment Facility (Miscellaneous Solid Waste Volume
 Reduction Treatment Building [High Temperature Incinerator Building] and
 the Process Main Building).
-From 2:37 pm on December 30 to 9:58 am on December 31, 2011, we
 transferred the accumulated water from the basement of turbine building
 of Unit 3 to the Centralized Radiation Waste Treatment Facility (the
 Miscellaneous Solid Waste Volume Reduction Treatment Building [High
 Temperature Incinerator Building] and the Process Main Building). 
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