* 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. 
  The current water injection volume is approx 7.6 m3/h from the reactor 
  feed water 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. 
 
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. 
  Water is currently injected at approx. 2.7 m3/h through reactor feed 
  water system piping arrangement, and at approx. 7.4 m3/h through core 
  spray system water injection piping arrangement. 
- 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. 
- We have been conducting gas analysis by using PCV gas management system 
  since October 28, 2011. However, it was found that some measurement 
  results collected on October 28, November 1, 2 and 14 were evaluated 
  about 10% lower in terms of the concentration of radioactive materials 
  due to computation process error. The error is limited to figures only, 
  and does not affect the criterion of criticality resumption nor evaluation 
  results. 
- At 11:04 am on November 6, we started operation of radioactive material 
  decontamination instrument of spent fuel pool. 
 
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. 
  Water is currently injected at approx. 2.5 m3/h through reactor feed 
  water system piping arrangement, and at approx. 8.1 m3/h through core 
  spray system water injection piping arrangement. 
- 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. 
 
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 11:34 am on August 20, we started an operation of desalination 
  equipment in the spent fuel pool. 
- 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 time, we don't think there is any reactor coolant leakage inside 
  the primary containment vessel. 
- From November 15, we started to cleanup work in order to prevent 
  performance deterioration of pump caused by inletting sand or other 
  materials piled up at the bottom of pump room of intake channel. 
 
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 9:10 am on November 10, we started transfer of accumulated water from 
  the basement of Unit 2 turbine building to Centralized Radiation Waste 
  Treatment Facility High Temperature Incinerator Building. 
- At 9:25 am on November 15, we started transfer of accumulated water from 
  basement of Unit 3 turbine building to Centralized Radiation Waste 
  Treatment Facility Building. 
- At 10:00 am on November 17, we started transfer of accumulated water from 
  Unit 6 turbine building to temporary tanks.