*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 9:37 am on January 29, due to switching in the water piping system of 
  the reactor water injection pump on the hill, we adjusted water  
  injection from the feed water system to the reactor of Unit 1 from  
  approx. 4.5 m3/h to approx. 5.5 m3/h, and the injection from the reactor  
  core spray system from approx. 2.0 m3/h to 1.0m3/h.  
  The Current water injection volume is approx. 5.5 m3/h from the reactor
  feed water system and approx. 1 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.
- At 5:10 pm on January 25, regarding the reactor injection from the feed
  water system at the Unit 2, we changed the injection line from the pump
  located uphill to the T/B reactor injecting pump. 
  The current water injection amount from the reactor feed water system is
  approx. 7.1 m3/h and that from the core spray system is approx. 1.7 m3/h.
- 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.
- At 10:46 am on December 1, 2011, we started the nitrogen injection to
  the Reactor Pressure Vessel.
- At 11:50 am on January 19, 2012, we started the operation of the spent
  fuel pool desalting facility.   

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 3:01 pm on January 27, the water injection to the reactor from the
  feed water injection system was switched from the reactor water
  injection pump in the turbine building to the reactor water injection
  pump on the hill. 
- At 10:00 am on January 29, since we confirmed decrease in water  
  injection to the reactor we adjusted water injection from the reactor   
  core spray system from approx. 1.5 m3/h to 2.0m3/h.  
  The current water injection amount from the reactor feed water system is
  approx. 7.1 m3/h and that from the core spray system is approx. 2 m3/h.  
- 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 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.
- At 3:18 pm on January 14, we started operation of the radioactive
  material removal instrument for the spent fuel pool in Unit 3   

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 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 10:00 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 8:00 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.
- As 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.
- From 10 :00 am to 4:00 pm on January 28, we transferred the accumulated
  water from the basement of T/B, Unit 6 to the temporary tank.
- At 10:06 pm on January 28, we started transferring accumulated water   
  from the basement floor of the turbine building of Unit 3 to the   
  Centralized Radiation Waste Treatment Facility (Miscellaneous Solid   
  Waste Volume Reduction Treatment Building [High Temperature Incinerator    
  Building] and the process main building). At 8:18 am of January 29 we   
  have stopped this transfer.  
- At 10:12 pm on January 28, we started transferring accumulated water  
  from the basement floor of the turbine building of Unit 2 to the  
  Centralized Radiation Waste Treatment Facility (Miscellaneous Solid  
  Waste Volume Reduction Treatment Building [High Temperature Incinerator  
  Building] and the process main building). At 8:21 am of January 29 we  
  have stopped this transfer. 
- At 8:49 am on January 29, since a gradual decline was confirmed in the  
  amount of treatment at the second Cesium adsorption apparatus (sally),  
  we temporarily stopped this facility in order to conduct reverse wash of  
  the filter.  
- At 9:50 am of January 29, one of our employees, during adjustment works 
  of the water flow to the feed water spray system, found a water leak  
  from near the flow rate detector of the emergency reactor injection pump  
  on the hill (C) which is now at standby. We shut down the valve at the  
  leakage point and at 9:55 am confirmed that the water leak has stopped  
  (amount of leakage under examination). The leakage point is on the hill  
  (at the front of the main office building) and there are traces that  
  show that a certain amount of water has flowed into the drain, and we  
  are examining whether this water has flowed into the ocean or not. The  
  surface radioactivity concentration near the leakage point is as the  
  same level as the atmosphere around (radioactivity concentration near  
  the evaporative concentration apparatus is below measurable limit in all  
  three major nuclides (sampled on 20 December 2011)  
  :I-134: 1.6X10-2Bq/cm3, Cs-134:2.9X10-2Bq/cm3, Cs-137:3.3X10-2Bq/cm3,   
  and 6.0X10-1Bq/cm3 for all beta nuclides (sampled on 29 November 2011).)   
  Water injection to the reactor is maintained by the ordinary reactor   
  injection pump on the hill (A) and (C).  
- Around 9:35am on 29 January 2012, an alarm on a system failure (Unit 4  
  SFP backup cooling system) was given in Unit 4 spent fuel pool backup  
  cooling system. According to the site investigation, a pump (A) to 
  circulate cooling water of a secondary system had been stopped and the  
  water circulation was stopped accordingly (Fuel pool temperature at the  
  time of the alarm: 21°C). After the event, we discovered cooling water  
  leakage from A2 line of air-fin cooler unit (A1-A4 lines) of the A  
  system of the secondary system. We confirmed that the water leakage was  
  stopped by closing valve of the Unit A2 line. The cooling water is from  
  a filtrate tank for fire extinction and doesn't contain radioactive  
  materials. The stopped secondary pump (A) was restarted at 11:14am and  
  water cooling of the spent fuel pool was restarted accordingly (Fuel  
  pool temperature at the time of cooling restart: 21°C)