*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 10:11 am on December 10, in addition to water injection from water
  feeding system, we started water injection from piping of core spray
  system to the reactor.
  The current water injection volume is approx 4.8 m3/h from the reactor
  feed water system and approx. 2.0 m3/h from the core spray 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.
- At 4:04 pm on November 30, we started operation to inject nitrogen into
  the reactor pressure vessel. 

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, in addition to water injection from water
  feeding system, we started water injection from piping of core spray
  system to the reactor.
  At 11:14 am on December 19, because we found decrease of water injection 
  rate from water feeding system, we adjusted injection rate from approx. 
  1 m3/h to approx. 3 m3/h (water injection from core spray system with 
  approx. 6 m3/h was continuing).  
  The current water injection volume is approx. 3 m3/h from the reactor
  feed water system and approx. 6 m3/h from the core spray system.
- 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.
- From 6:00 pm on October 28, we put the gas management system of the
  reactor containment vessel in operation.
- At 10:46 am on December 1, we started the nitrogen injection to the
  Reactor Pressure 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. 
  The current water injection volume is approx 2.8 m3/h from the reactor
  feed water system and approx. 5.8 m3/h from the core spray system.
- 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. 
- At 4:26 pm on November 30, we started operation to inject nitrogen into
  the reactor pressure vessel. 

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 10:58 am on November 29, in order to decrease more salinity, we
  installed Ion exchange equipment and started the operation of such
  equipment.
- 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 2:45 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 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 moment, we do not think there is any reactor coolant leakage
  inside PCV. 

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.
- At 12:25 pm on December 13, we started the re-circulating operation of
  desalination facility (reverse osmosis membrane type) for the purpose of
  suppression of condensed water after desalination treatment.
- At 11:11 am on December 19, we found water drops on a few drops per 
  second from connection point of the valve and piping of pressure 
  indicating instrument of secondary coolant system of alternative cooling 
  system of spent fuel pool of Unit 1. At 11:55 am on the same day, we 
  tightened the connection point and then water drops stopped. The dropped 
  water was filtrate water (fresh water) and no radioactive material was 
  contained. Also, alternative cooling system of spent fuel pool was in 
  operation continuously and there is no problem on cooling.