*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 7.8 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. 2.9 m3/h through reactor feed 
  water system piping arrangement, and at approx. 7.3 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 11:04 am on November 6, we started operation of radioactive material 
  decontamination instrument of spent fuel pool. 
- 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. 
 
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. 2.3 m3/h through reactor feed 
  water system piping arrangement, and at approx. 8 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. 
 
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. 
- From 10:00 am to 4:00 pm on November 9, transfer of accumulated water 
  from turbine building of unit 6 to temporary tank was conducted. 
- 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. 
- On November 9, sampling survey of gas at the gas management system of 
  Unit 2 primary containment vessel was implemented. According to its 
  analysis, it is considered that recriticality was not occurred because 
  radioactive Xe135 at the entrance of gas management system of Unit 2 was 
  below detection limit (1.1 x 10-1Bq/cm3). In addition, Xe-135 
  (1.9 x 10-5Bq/cm3) was detected by charcoal filter. This was measured 
  value and evaluated to be the amount emitted from the gas management 
  system. Thus, the value measured by gas vial was converted into the 
  value of 1.1 x 10-2Bq/cm3 using achievement rate. This value was the 
  same as 2.7 x 10-2Bq/cm3 that was evaluated before. 
- It turned out that pressure in D/W of Unit 2, which is one of the plant 
  parameter, such as water level, pressure of temperature, was incorrect 
  from 11:00 pm on October 29 to 11:00 pm on 10 November. This is because 
  the pressure loss in the pipe for additional amount of injected nitrogen 
  gas was not considered for the calculation of the pressure in D/W 
  although injected amount of nitrogen gas has been increased 
  appropriately since October 28 when the operation of gas management 
  system of primary containment vessel started. Because revised pressure 
  in D/W calculated by correct pressure loss in the pipe exceeds 
  atmospheric pressure, there is no problem about its safety. The revision 
  of value of the past data will be informed separately.