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Corporate Information

 
Press Release (Dec 27,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 3:00 pm, December 27)

*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. 4.4 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.
  At 11:00 am on December 27, regarding the water injection into the 
  reactor core of unit 2, for the purpose of preparation of commissioning 
  of water injection pumps for diversification, water injection rate from 
  feed water system was adjusted from approx. 2.8 m3/h to 2.0 m3/h, from 
  core spraying system was adjusted from approx. 6.0 m3/h to 7.0 m3/h. 
  The current water injection volume is approx. 2.0 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). Expected temperature increase will be 
  approx. 0.3°C/h (suspension period will be approx. 1 hour) and there is 
  no concern to the water temperature of the spent fuel pool. 
- 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 2:00 pm on December 26, in the alternative cooling system of the spent 
  fuel pool, 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 the 
  spent fuel pool (the temperature of the pool at the time of the 
  suspension was approx. 13°C). After flashing, as inhale pressure of the 
  pump has recovered, at 4:32 pm on the same day, the pump was restarted 
  and cooling of spent fuel pool was restarted (the temperature of the pool 
  at the time of restart was approx. 13°C).
- 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 6:00 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.
- 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.
- Due to the completion of restoration of residual heat recovery (RHR) sea 
  water pump (A) of unit 6, which was not be able to use by the affect of 
  tsunami, at 10:19 am on December 27, commissioning was started, at 11:30 
  am as no incident was observed, it returned to usual operation. As a 
  result, two RHR pumps, (A) and (C), had been returned to service. During 
  the commissioning, while RHR pump (A) of unit 6 was temporary stopped 
  from 10:01 am to 11:09 am and cooling of reactor core was suspended, as 
  the increase of core water was approx. 0.7°C and there were no concerns 
  to the safety. 
- 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.
  The second Cesium adsorption apparatus, which has been shut down since 
  8:44 am on December 12, restarted at 10:37 am on December 27. Treatment 
  of accumulated water restarted which has been suspended since December 20. 
- 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.
- From 10 am to 4 pm on December 26, we transferred accumulated water from 
  the Turbine Building of Unit 6 to the temporary tank.
- From 10:10 am on December 26 to 9:54 am on December 27, we transferred 
  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).
- On December 26, two of TEPCO's employee who were engaged in recovery 
  work at Fukushima Daiichi Nuclear Power Station was diagnosed as 
  influenza. On December 27, one TEPCO's employee who was also engaged in 
  recovery work at Fukushima Daiichi Stabilization Center was newly 
  diagnosed as influenza. We will take countermeasure for infection and 
  escalation prevention by promoting hand washing, gargle, finger 
  disinfecting and cough etiquette and will endeavor to set and use 
  thermometer, finger disinfecting alcohol, mask.
- At 10:14 am on December 27, we started transfer of accumulated water from 
  site banker to process main building in the centralized radiation waste 
  treatment facility. 
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