*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.
  At 2:59 pm on October 31, we adjusted the amount of water injection to 
  the reactor to approximately 7.5m3/h in order to improve the working 
  environment inside the covering, making it sure to mitigate the steam 
  emission at the reactor building of Unit 1 
  The current water injection volume is approx 7.5 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. 2.5m3/h through reactor feed
  water system piping arrangement, and at approx. 6.9 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 10:12 am to 11:50 am on Octorber 31, 
  hydrazine [corrosion preventive] was also injected). 
- At 8:06 pm on June 28, we started injecting nitrogen gas into the
  Primary Containment Vessel.
- At 12:53 pm on October 28, we activated the exhaust fan of the gas
  management system of the reactor containment vessel in the reactor
  building and started test operation. As we confirmed stable operation
  of the system, from 6:00 pm on the same day, we put the system in
  operation. Regarding the hydrogen concentration of the gas management
  system of the reactor containment vessel in Unit 2, we confirmed that
  it increased to approx. 2.7vol% at 5:00pm on October 30, which was
  approx. 1vol% at the beginning of the operation. Therefore we adjusted
  the amount of injecting nitrogen gas to the Primary Containment Vessel
  from approx.16.5 N m3/h to 21 N m3/h at 6:10 pm on October 30 in order
  to avoid exceeding the combustible threshold concentration (4vol%) of
  hydrogen. 

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. 

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 10:12 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 9:32 am
  on October 28, we stopped transferring the accumulated water from the
  basement of turbine building of Unit 2 to the Process Main Building of
  Central Radioactive Waste Treatment Facility temporarily, and after
  checking the systematic diagram, from 9:54 am on October 28 to 10:02 am 
  on October 31, the accumulated water has been transferred from Unit 2 
  turbine building basement to High Temperature Incinerator Building of 
  Centralized Radiation Waste Treatment Facility. 
- 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 10:00 am on October 31, we started transferring accumulated water
  from the temporarily built tank to Mega-float.