*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. 4.3 m3/h from the reactor
  feed water system and approx. 2 m3/h from the core spray system.
  At 9: 44 am on December 30, the injected water amount was adjusted from 
  approx. 4.4 m3/h to approx.4.5 m3/h in feed water system, from approx. 
  1.8 m3/h to approx.2.0 m3/h in corer spray system as the change in the 
  injected water amount was observed. Current water injection amount is
  approx.4.5 m3/h in feed water system and approx.2.0 m3/h in corer 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.
- At 6:00 pm on December 19, a full-scale operation of the PCV gas
  management system started.

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.
  The current water injection volume is approx. 1.8 m3/h from the reactor
  feed water system and approx. 7.0 m3/h from the core spray system.
  At 9: 44 am on December 30, the injected water amount was adjusted from 
  approx. 1.8 m3/h to approx.2.0 m3/h in feed water system (no change in 
  corer spray system with approx. 7.0 m3/h) as the change in the injected 
  water amount was observed. Current water injection amount is approx.
  2.0 m3/h in feed water system and approx.7.0 m3/h in corer 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.
- At 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 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, 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 10:11 am on December 22, 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, 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.
- Since December 22, 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 Nm3/h to approx.18 Nm3/h, and emission of the gas
  management system, from approx. 23 Nm3/h to approx.30 Nm3/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 pm on December 28 and fell to approx. 49.2°C at 5 am on 
  December 30. 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 → approx. 
   35.0°C at 5:00 am on December 30. 
   Point E: (Maximum) approx. 40.0°C at 5:00 pm on December 29 → approx. 
   39.1°C at 5:00 am on December 30. 
   We will continuously conduct the survey for the cause of temperature
   increase and surveillance of the plant.
- At 3:22 pm on December 28, 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).