*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. 3.7 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. 3.4m3/h through reactor feed 
  water system piping arrangement, and at approx. 7 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.
- From 11:20 am to 11:52 am on October 21, aiming to restore the function 
  of primary reactor water level gauge, we filled the measurement piping 
  with water from makeshit gauge (gauge in the makeshift lac) in the 
  primary reactor Water Level Gauge in Unit 2. 
- 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. 2.1m3/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. From 1:01 pm to 2:41pm on October 20, we 
  injected hydrazine [Anti-corrosion chemicals] to spent fuel pool.
- 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.
- For the purpose water intake inspection, at 9:05 am October 21, seawater 
  pump of Equipment Water Cooing System (A) was first shutdown, and at 
  9:13 am, Residual Heat Removal System (A) pump was stopped, and stopped 
  cooling the reactor. At 9:15 am, Residual Heat Removal System seawater 
  pump (C) was stopped.
- 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 6:09 am on October 18, we suspended the Cesium adsorption apparatus 
  unit No.1 due to power reinforcement works of the water desalinations. 
  At 9:04 am we suspended Unit No, 2. At approximately 11:00 am, while we 
  were replacing the motor of the pumps (H2-2) in the skid of the 
  suspended Cesium absorption apparatus, a puddle of water was found in 
  the skid (depth approx. 15 cm, volume approx. 3 m3). We also found that 
  the leakage already stopped when we found the puddle of water. After 
  that, we interrupted the work of change of the motor and conducted 
  draining the water by underwater pump. The cause is currently under 
  investigation.
- At 10am on October 21, we started the transfer of accumulated water from 
  temporary tank to mega float. 
- 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.