* 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.
  As it was confirmed that there was fluctuation in the amount of water 
  injection for the reactor at 10:57 am on January 1, 2012, we adjusted the 
  rate of water injection from piping of core spray system from 1.8 m3/h to 
  approx. 2 m3/h. (Water injection is continuously implemented at the rate 
  of 4.5 m3/h from water feeding system) 
  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.
  As it was confirmed that there was fluctuation in the amount of water 
  injection for the reactor at 10:15 am on January 1, 2012, we adjusted the 
  rate of water injection from water feeding system from 1.8 m3/h to approx. 
  2 m3/h. We also adjusted the rate of water injection from piping of core 
  spray system from 7.1 m3/h to approx. 7 m3/h.  
  Current water injection amount is approx.2 m3/h in feed water system and 
  approx.7 m3/h in corer 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, we put the gas management system of the 
  reactor containment vessel in operation.
- 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. 
  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 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.
  Since inlet pressure of the primary circulation pump in the alternative 
  cooling system of the spent fuel pool frequently tended to decrease due 
  to the effect of clogging of the inlet strainer of the pump, the pump was 
  stopped at each time in order to flush the strainer. However, since this 
  tendency is supposed to continue and the temperature of the spent fuel 
  pool is sufficiently low, which is approx. 13.0°C, and there is enough 
  margin from the operational limit value (upper limit) by the safety 
  regulation, which is 65.0°C, we determined to stop the pump by January 4 
  of 2012 and temporary stop the cooling of spent fuel pool, considering 
  the exposure dose during the flushing.
  At 4:54 pm on December 30, 2011, the pump was stopped. (Temperature of 
  the spent fuel pool was approx. 13.3°C at the time of shutdown.) It is 
  valuated that the temperature rise of the spent fuel pool due to the 
  shutdown of the pump is approx. 5 to 6 degrees for a day. And it is 
  planned that this pump operates for one time in a day to check the 
  temperature of the spent fuel pool during this temporary operation, since 
  December 31, 2011.
- 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 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.
- Since December 22, 2011, the atmospheric temperatures at point C of Unit 
  1 Primary Containment Vessel (PCV) monitored by the Containment 
  Atmospheric Monitoring System had risen (the atmospheric temperature of 
  the PCV on December 22 was approx. 38°C, at 7 pm on December 27 was 
  approx. 49°C). The other temperatures had not risen, so we conducted a 
  survey checking the reliability of the meters from 9 am to 10 am on 
  December 28, and we confirmed that there are no problems. From 11:00am to 
  12:15pm on the same day, we adjusted the volume of Nitrogen injection, 
  from approx. 8 m3/h to approx.18 m3/h, and emission of the gas 
  management system, from approx. 23 m3/h to approx.30 m3/h, in order to 
  identify the cause by monitoring the system with the same injection and 
  emission volume as before December 22. The temperature went up to approx. 
  54.6°C at 6:00 pm on December 28 at its maximum and fell to approx. 
  44.4°C at 11:00 am on January 1, 2012. Temperatures at other two points 
  also indicated slight increases but are currently in the stable status.
   Point D: (Maximum) approx. 35.8°C at 5:00 pm on December 29, 2011 → 
            approx. 32.9°C at 11:00 am on January 1, 2012. 
   Point E: (Maximum) approx. 40.0°C at 5:00 pm on December 29, 2011 → 
            approx. 36.3°C at 11:00 am on January 1, 2012. 
  We will continuously conduct the survey for the cause of temperature 
  increase and surveillance of the plant.
- At 3:22 pm on December 28, 2011, we started to transfer accumulated water 
  from the basement of 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).
- From 2:37 pm on December 30 to 9:58 am on December 31, 2011, we 
  transferred the accumulated water from the basement of turbine building 
  of Unit 3 to the Centralized Radiation Waste Treatment Facility (the 
  Miscellaneous Solid Waste Volume Reduction Treatment Building [High 
  Temperature Incinerator Building] and the Process Main Building).