*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.
  Water is currently injected at approx. 3.8 m3/h through reactor feed 
  water system piping arrangement. 
- 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. 
- At 1:17 pm on October 26, we started cutting off the designated piping 
  after confirming that the hydrogen density inside the piping for cooling 
  in case of reactor shutdown was less than 0.1 %, as one of the 
  construction work to install gas monitoring system inside the Primary 
  Containment Vessel. At 3:15 pm on the same day, we finished cutting pipes. 
  After that, we conducted welding of blind plates of cut pipes and 
  covering holes of the pipes. At 7:00 pm on the same day, we finished all 
  operations. 

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. 2.9m3/h through reactor feed 
  water system piping arrangement, and at approx. 7.0 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.
- At 9:55 am on October 27, for the water injection line of Unit 2, we 
  switched from normal water injection line to emergency water injection 
  line due to installation work of additional flow control valve to improve 
  controllability of amount of water injection. 

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. 2.9 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 time, 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.
- At 10:00 am on October 20, we started transferring the accumulated water 
  from the basement of turbine building of Unit 3 to the High Temperature 
  Incinerator Building of Central Radioactive Waste Treatment Facility.
- At 10:12 am on October 20, we started transferring the accumulated water 
  from the basement of turbine building of Unit 2 to the Process Main 
  Building of Central Radioactive Waste Treatment Facility.
- From 5:31 pm on October 25 to 2:01 pm on October 26, we transferred the 
  accumulated water brought from the basement of turbine building of Unit 
  1 to the basement of turbine building of Unit 2. 
- From 10:00 am to 4:00 pm on October 26, we transferred the accumulated 
  water from the basement of turbine building of Unit 6 to the temporary 
  tanks. 
- On October 26, we replaced the hose for transferring reverse osmosis 
  membrane concentrated water in Water Desalinations (reverse osmosis 
  membrane) that liquid spoil was found on October 8,
- At 9:47 am on October 26, for the water injection to the reactors of 
  Units 1 to 3, we switched from normal water injection line to emergency 
  water injection line, due to the shutoff of facilities for power source 
  reinforcement work. After that, we switched from emergency water 
  injection line to normal water injection line due to completion of power 
  source reinforcement work. (At 4:10 pm on the same day, we confirmed flow 
  rate stability of Unit 1 and 2. At 3:33 pm on the same day, we confirmed 
  flow rate stability of Unit 3) Along with the switching work, we adjusted 
  the amount of water injection from water feeding system to approximately 
  3.8 m3/h for Unit 1's reactor. For Unit 2, we adjusted the amount of 
  water injection to the reactor to approximately 3 m3/h from water feeding 
  system and to approximately 7 m3/h from Core Spray System. Likewise, for 
  unit 3, we adjusted the amount of water injection to the reactor to 
  approximately 3 m3/h from water feeding system and to approximately 8 m3/h 
  from Core Spray System. 
- At 10:00 am on October 27, we started transferring accumulated water from 
  the temporary tank to the Mega Float.