*The 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, 2011. It was assumed to be hydrogen 
  explosion.
- At 3:37 pm on March 25, 2011, 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, 2011, in addition to water injection from 
  water feeding system, we started water injection from piping of core 
  spray system to the reactor.
- At 11:07 am on January 12, 2012, we adjusted the amount of the water 
  injection from approx. 4.6 m3/h to approx. 4.5 m3/h (the reactor feed 
  water system), from approx. 1.6 m3/h to approx. 2 m3/h (the core spray 
  system) since we confirmed fluctuation of the amount of the water 
  injection into the reactor.  
  Current water injection volume is approx. 4.5 m3/h from the reactor feed 
  water system and approx. 2 m3/h from the core spray system.
- At 1:31 am on April 7, 2011, we commenced injection of nitrogen gas into 
  Primary Containment Vessel.
- At 11:22 am on August 10, 2011, 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, 2011, 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, 2011, we started operation to inject nitrogen 
  into the reactor pressure vessel.
- At 6:00 pm on December 19, 2011, a full-scale operation of the PCV gas 
  management system started. 

Unit 2 (Shut down) 
- At approximately 6:00 am on March 15, 2011, an abnormal noise began 
  emanating from nearby Pressure Suppression Chamber and the pressure 
  within the chamber decreased. 
- At 10:10 am on March 26, 2011, 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, 2011, in addition to water injection from 
  water feeding system, we started water injection from piping of core 
  spray system to the reactor.
  Current water injection volume is approx. 2.8 m3/h from the reactor feed 
  water system and approx. 7.1 m3/h from the core spray system.
- At 5:21 pm on May 31, 2011, 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, 2011, we started injecting nitrogen gas into the 
  Primary Containment Vessel.
- At 6:00 pm on October 28, 2011, a full-scale operation of the PCV gas 
  management system started.
- On January 11, 2012, we conducted sampling survey of the gas in the 
  primary containment vessel gas management system. As a result of the 
  analysis, we confirmed that at the gate of the system the density of 
  xenon 135 was below the measurable limit (1.1 x 10-1 Bq/cm3) and thus it 
  was lower than the judgment criteria for the recriticality, 1Bq/cm3. 
- At 10:46 am on December 1, 2011, 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, 2011. It was assumed to be hydrogen explosion.
- At 6:02 pm on March 25, 2011, 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, 2011, we started water injection by core spray 
  system in addition to water injection by the reactor feed water system 
  piping arrangement.
- At 10:30 am on January 12, 2012, we adjusted the amount of the water 
  injection from approx. 1 m3/h to 0 m3/h (the reactor feed water system), 
  from approx. 8.2 m3/h to approx. 9.0 m3/h (the core spray system) in 
  order to switch the injection pipe arrangement of the reactor feed water 
  system for preparation for test operation of the reactor injection pump 
  in the turbine building. At 11:00 am, we adjusted the amount of the water 
  injection from approx. 0 m3/h to 1 m3/h (the reactor feed water system), 
  from approx. 9 m3/h to approx. 8 m3/h (the core spray system) since the 
  switch work was completed.  
  Current water injection volume is approx 1 m3/h from the reactor feed 
  water system and approx. 8 m3/h from the core spray system.
- At 7:47 pm on June 30, 2011, 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 9:35 am on January 12, we stopped the Unit 3 spent fuel pool 
  alternative cooling system in order to install a radioactive materials 
  removal equipment in the Unit 3 spent fuel pool (the temperature of the 
  spent fuel pool at the time of the stoppage: approx. 12.7°C). As the 
  estimated increase of the temperature is 0.22°C/h (the outage time: 
  approx. 4 hours 30 minutes), there is no problem regarding the 
  temperature of the spent fuel pool. 
- At 8:01 pm on July 14, 2011, injection of nitrogen gas into the Primary 
  Containment Vessel started. 
- At 4:26 pm on November 30, 2011, 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, 2011, 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, 2011, 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 1:30 pm on January 12, 2012, we started 
  the injection of hydrazine [corrosion inhibitor] in conjunction with the 
  cyclic cooling). 
- At 10:58 am on November 29, 2011, 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, 2011, we started the Residual Heat Removal System 
  Pump in order to cool the spent fuel pool.
- At 2:45 pm on July 15, 2011, we started the operation of the original 
  Residual Heat Removal System (System B) by its original seawater pump.
- At 10:11 am on December 22, 2011, since we finished the recovery work of 
  seawater pump (System B) of equipment water cooling system, we made a 
  trial run. At 11:25 am on the same day, we confirmed no abnormalities 
  and restarted the operation.
- 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, 2011, we started the Residual Heat Removal 
  System Pump of Unit 6 to cool down Spent Fuel Pool.
- At 2:33 pm on September 15, 2011, 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, 2011, 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, 2011, 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, 2011, 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, 2011, 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, 2011, 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, 2011, we started the re-circulating operation 
  of desalination facility (reverse osmosis membrane type) for the purpose 
  of suppression of condensed water after desalination treatment.
- From 10:15 am on January 12 to 12:50 pm on January 12, 2012, we conducted 
  the transfer of the tank storage water from the Unit 3 condensate storage 
  tank to the basement of the Unit 2 turbine building. 
- Because of the finding of accumulated water containing radioactive 
  materials at the trench between the Process Main Building and the 
  Miscellaneous Solid Waste Volume Reduction Treatment Building[High 
  Temperature Incinerator Building](December 18, 2011), we started the 
  inspection of other trenches at the site on January 11.
  In the inspection conducted on January 12, we confirmed a puddle in the 
  Unit 3 transformer cable duct for activation. As a result of nuclide 
  analysis, the radioactive concentration of the puddle water is below 
  measurable limit for I-131, 4.9x101Bq/cm3 for Cs-134, 6.9x101Bq/cm3 for 
  Cs-137 (Total of the major three nuclides reaches 100Bq/cm3). As 
  indicated above, it was found out that the water contained relatively 
  highly-concentrated radioactive materials. We presume that the 
  accumulated water in the building is not likely to have flown into the 
  cable duct since the water level (water surface) of the puddle is higher 
  than that of the accumulated water in the building.