* 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 3:50 pm on January 30, since we finished the replacing the water 
  injection line of the reactor water injection pump on the hill to 
  polyethylene pipe in order to improve the reliability of water injection 
  to the reactor, we changed the water injection volume to the reactor 
  gradually. Then, we adjusted the water injection volume through the feed 
  water system from approx. 6.5 m3/h to approx. 5.5 m3/h, and that through 
  the reactor core spray system from 0 m3/h to approx. 1m3/h. 
  At 10:15 pm on January 30, since the decrease of water injection rate was 
  confirmed, we adjusted the amount of water injection to the reactor of 
  Unit 1 through core spray system from approx.0.5 m3/h to approx.1.0 m3/h. 
  (Continuing water injection from feeding water system at approx.5.8 m3/h.) 
  The current water injection amount from the reactor feed water system is 
  approx. 5.8m3/h and that from the core spray system is approx. 1m3/h.
- 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. 
  At 3:05 pm on January 30, we stopped the operation of the secondary 
  air-fin coolers of spent fuel pool in order to prevent overcooling of 
  alternative cooling system of spent fuel pool of Unit 1. (the temperature 
  of fuel pool at the time of stoppage: 12°C) 
- 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. 6.4m3/h and that from the core spray system is approx. 2.9m3/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.
  The current water injection amount from the reactor feed water system is 
  approx. 6.1m3/h and that from the core spray system is approx. 2.8m3/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 4:27 pm on January 29, we temporally suspended Air fin cooler of 
  secondary system of spent fuel pool in order to prevent over cooling of 
  alternative cooling system of spent fuel pool.
  (Fuel pool temperature at the time of stoppage: 21°C)
  At 3:13 pm on January 30, we restarted the operation of the air-fin 
  cooler. (the temperature of fuel pool at the time of restart: 29°C) 
- 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.
  As a result of the inspection of January 30, the locations where 
  accumulated water was discovered and the nuclide analysis results are as 
  follows:  
   · Unit 2 Transformer trench for disaster prevention 
   I-131: below measurable limit, Cs-134: approx. 2.1x100Bq/cm3, Cs-137: 
   approx. 3.0x100Bq/cm3 
- At 4:05 pm on January 30, we started to transfer the accumulated water 
  from the basement of T/B, Unit 2 to the Centralized Waste Treatment 
  Facility (Miscellaneous Solid Waste Volume Reduction Treatment Building 
  [High Temperature Incinerator Building] and Process Main Building) 
  through newly installed polyethylene pipes. 
- At 4:12 pm on January 30, we started to transfer the accumulated water 
  from the basement of T/B, Unit 3 to the Centralized Waste Treatment 
  Facility (Miscellaneous Solid Waste Volume Reduction Treatment Building 
  [High Temperature Incinerator Building] and Process Main Building) / 
  through newly installed polyethylene pipes. 
- On January 30, we conducted night patrol due to water leakage that was 
  thought to be due to freezing. At 10:50 pm on the same day, we found 
  something that looked like crack that was thought to be due to freezing 
  at valve box of filtrate water side piping at the entrance of the reactor 
  water injection pump (C) on the hill. The surface water of this point has 
  been freezing and we found no water leakage. From this time, we will 
  review the implementation of valve replacement and measure against 
  freezing. 
 
  · The water leakage newly found from the previous release (as of 10:00 am 
  on January 30) was as follows; 

  ○ Valve box of filtrate water side piping at the entrance of the reactor 
     water injection pump 
     (C)on the hill. (Found at around 3:15 pm on January 30) 
     (Filtrate water*: the width is equivalent to approx. 2 pencils) 
  ○ The exit line flange of seal water cooler of evaporative concentration 
     apparatus 3A 
     (Found at around 3:20 pm on January 30) 
     (Filtrate water*: 2 drops per approx. 1 second) 
  ○ The condensed water return line flange of evaporative concentration 
     apparatus (A) 
     (Found at around 9:05 am on January 31) 
     (Filtrate water*: approx. 20 L ) 

     * Filtrate water: water taken from the barrage 
- At 9:35 am on January 31, we started transfer of accumulated water from 
  site banker to process main building in the centralized radiation waste 
  treatment facility. 
- At 10:00 am on January 31, we started transfer of accumulated water from 
  the basement of turbine building of Unit 6 to the temporary tanks.