* 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.
  The current water injection volume is approx 4.2m3/h from the reactor 
  feed water 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 4:08 pm on November 30, injection amount 
  reached the scheduled amount of 5 N m3/h. 
 
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, we started injecting water to the reactor 
  through core spray system water injection piping arrangement in addition 
  to the water injection through reactor feed water system piping 
  arrangement.
  Water is currently injected at approx. 3.1m3/h through reactor feed water 
  system piping arrangement, and at approx. 4.3 m3/h through core spray 
  system water injection piping arrangement.
- 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 11:13 on November 30, the alarm went off at the alternative cooling 
  system in the Fuel Pool Cooling and Filtering System indicating that 
  the difference of the flow rate between at the inlet and at the outlet is 
  large and the system automatically stopped its operation. At 11:34 pm on 
  the same day, no leakage was confirmed by the site inspection. At 11:00 
  pm on the same day, the temperature of spent fuel pool was 22.7 °C and the 
  anticipated temperature increase was 0.3 °C/h. As there is sufficient 
  buffer, the inspection is scheduled during the morning of December 1. 
  However, the inspection, the repair work and the cause analysis is 
  rescheduled to December 2 as it turned out that the material preparation 
  for such work needs time. We expect no major issue for the continued 
  system outage as the temperature of spent fuel pool was 23.8 °C the at 
  1:00 pm on December 1 (1.1°C increase from 11:00 pm on November 30) and 
  the increase is not material.
- At 8:06 pm on June 28, we started injecting nitrogen gas into the Primary 
  Containment Vessel.
- From 6:00 pm on October 28, we put the gas management system of the 
  reactor containment vessel in operation.
- At 11:04 am on November 6, we started operation of radioactive material 
  decontamination instrument of spent fuel pool.
- 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. 
  Water is currently injected at approx. 2.1 m3/h through reactor feed 
  water system piping arrangement, and at approx. 6.1 m3/h through core 
  spray system water injection piping arrangement.
- 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.
- At 9:01 am on December 2, we interrupted the operation of the alternative 
  cooling in order to replace the primary strainer as a countermeasure 
  against the decrease in inhale pressure of the primary pump for 
  alternative cooling of the spent fuel pool. The temperature of the spent 
  fuel pool as at the interruption was 18°C and expected temperature 
  increase was 0.2°C/h (duration of interruption: approx. 3hours). The 
  water temperature of the spent fuel pool is in a normal state. 
 
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.
- Regarding spent fuel pool for unit 4, from August 20 to November 8, we 
  had decreased salinity by using the desalting facility. In order to 
  decrease more salinity, we installed Ion exchange equipment and started 
  the equipment at 10:58 am on November 29.
- 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 2:30 pm on March 20, the reactor achieved cold shutdown.
- 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.
- From November 28, we started cleaning to avoid the performance 
  deterioration of pumps by sucking up sands etc. accumulated at the bottom 
  of the inlet canal pump room.
- 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 7:27 pm on March 20, the reactor achieved cold shutdown. 
- 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 9:25 am on November 15, we started transfer of accumulated water from 
  basement of Unit 3 turbine building to Centralized Radiation Waste 
  Treatment Facility Building.
- At 6:03 pm on November 30, we started transfer of the accumulated water 
  from the basement of Unit 2 turbine building to Centralized Radiation 
  Waste Treatment Facility High Temperature Incinerator Building.
- At 10:00 am on December 1, we started transfer of the accumulated water 
  from Unit 6 turbine building to Temporary Tank.
- At 10:47 pm on November 18, desalination plant (RO) unit 2-2 
  automatically suspended due to alarm indicating high pressure of treated 
  water at outlet side. On November 22, we checked outside of the unit and 
  found no trouble, and so we remove the discharged water in drain line at 
  exit side of the Unit and reset the alarm. At 2:00 pm on the same day, we 
  restarted the Unit. While we had been checking the operation of the Unit, 
  at 9:56 am on November 23, the alarm occurred again indicating the high 
  pressure of treated water at the exit side of Unit2-2, and the unit 
  stopped automatically. Then, through the external inspection of the 
  equipments (on damage or leakage) and the confirmation of operation state 
  based on the indicators we confirmed that it could be operated. At 11:20 
  am on December 1, we replaced the pressure button which was seemed to be 
  one of the causes of the alarm and restarted the desalination (RO) unit 
  2-2. We will keep monitoring its operation state.