*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. 3.5 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. 

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. 3.1m3/h through reactor feed water 
  system piping arrangement, and at approx. 7.2 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. 

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. 2.0 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.
- At around 2 pm on October 23, TEPCO's employee found seemingly oil spill 
  outside the oil retaining wall of temporary oil tank for main transformer 
  in the power plant premise (Wild Bird Forest). At around 2 pm on October 
  24, we confirmed at the site that there were oil film in the water 
  accumulated in the oil retaining wall and the oil was accumulated in the 
  space which the water in the oil retaining wall spilled. From these 
  reasons, we assumed that the oil observed on October 23 was the oil which 
  spilled from the oil retaining wall by inflow of rain water to the wall. 
  At this moment, we are investigating in detail, including nuclide 
  analysis for the water accumulated in the wall and analysis on the oil film. 
- At around 11:30 am on October 24, as water leakage (about 20 litters) 
  from the pump gland at RO membrane unit was found, the Water Desalination 
  Facility was shutdown. Afterward, the water leakage was confirmed to be 
  stopped. At 2:30 pm on the same day, we stopped the line connecting to 
  the water pump and started other water desalinations. At 4:20 pm on the 
  same day, the rated flow reached 50 m3/h. 
- From 10 am on October 25, we started transferring the accumulated water 
  from the temporary tanks to the mega float.