search



Corporate Information

 
Press Release (Dec 10,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 3:00 pm, December 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 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. 1 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. 
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, we started injecting water to the reactor 
  through core spray system water injection piping arrangement in addition 
  to the water injection through reactor feed water system piping 
  arrangement.
  At 11:25 am on December 10, we adjusted water injection volume through 
  the core spray system from approx. 4.5 m3/h to approx. 5.5 m3/h in order 
  to cool down the reactor stably. 
  The current water injection volume is approx 2.9 m3/h from the reactor 
  feed water system and approx. 5.5 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 8:06 pm on June 28, we started injecting nitrogen gas into the Primary 
  Containment Vessel.
- From 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.
- At 4:17 am on December. 7, on the alternative Spent Fuel Pool cooling 
  system of Unit 2, the alarm indicating that the difference of flow rates 
  between at the entering and at the exit of the primary pump is big went 
  off, and the system stopped automatically. At 4:41 on the same day, after 
  field investigation, no defect such as leakage was confirmed. After that, 
  as any troubles are not detected although we conducted flushing of flow 
  rate measure and detection line and filling water, the cause of the alarm 
  was not indentified. As temporary operation procedure to identity the 
  cause, we deleted the condition of automatic shutoff by the alarm 
  indicating that the difference of flow rates between at the entering and 
  at the exit of the primary pump is big. In addition, for the alternative 
  monitoring method, we strengthen monitoring of the water level of skimmer 
  surge tank and change the operation procedure to stop the system manually 
  when system troubles occurred. After that, at 11:37 am on December 10, we 
  restarted cooling of the spent fuel pool by this system. (Water 
  temperature of spent fuel pool at the injection restarted :31.3 °C)
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. 
  At 11:25 am on December 10, we adjusted water injection volume through 
  the water feeding system from approx. 2.2 m3/h to approx. 3.2 m3/h in 
  order to cool down the reactor stably. 
  The current water injection volume is approx 3.2 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.
- 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 2:30 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 (System B) by its original seawater pump.
- 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 7:27 pm on March 20, the reactor achieved cold shutdown. 
- 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 6:03 pm on November 30, we started transfer of the accumulated water 
  from the basement of Unit 2 turbine building to Centralized Radiation 
  Waste Treatment Facility High Temperature Incinerator Building.
- From 9:00 am to 10:30 am on December 9, we conducted dust sampling above 
  the reactor building of Unit 3 with a large crane.
- At 2:00 pm on December 10, we started transferring of accumulated water 
  from underground of the Turbine Building of Unit 1 to underground of the 
  Turbine Building of Unit 2. 
back to page top


to TOP