*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.
  On December 7, as a part of installation work of the Primary Containment 
  Vessel Gas Management System in the Unit 1 reactor building, we conducted 
  nitrogen substitution in order to eliminate hydrogen in the existing pipe 
  arrangement to be used in the system. At 10:29 am on December 8, we 
  activated an exhaust fan in the Primary Containment Vessel Gas Management 
  System and started test operation of the system.

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. 3m3/h through reactor feed water 
  system piping arrangement, and at approx. 4.1m3/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 8:06 pm on June 28, we started injecting nitrogen gas into the Primary 
  Containment Vessel.
  At 4:15 pm on December 8, as it is considered that there would be 
  sufficient time before hydrogen reach the flammability limit in the 
  Primary Containment Vessel, the nitrogen injection amount into the PCV 
  was decreased from 20 Nm3/h to 16.5 Nm3/h. 
- 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. On December 5, the 
  facilities finished its operation.
- At 10:46 am on December 1, we started the nitrogen injection to the 
  Reactor Pressure Vessel.
  At 4:15 pm on December 8, in order to secure the sufficient time before 
  hydrogen reaching the flammability limit in case the nitrogen injection 
  facilities stop its operation in the Unit 2 Reactor Pressure Vessel, 
  nitrogen injection amount into the RPV was increased from 13 Nm3/h to 
  14.5 Nm3/h. 
- At 4:17 am on December. 7, on the alternative Spent Fuel Pool cooling 
  system of Unit 2, the alarm indicating that the difference of flow rates 
  between at the entering and at the exit of the primary pump is big went 
  off, and the system stopped automatically. At 4:41 on the same day, after 
  field investigation, no defect such as leakage was confirmed. Currently 
  the cause is under investigation,. At 4:00 am, the temperature of Spent 
  Fuel Pool was 18.4 degree C, the assumed increase of temperature is 0.3 
  degree C/h, from the viewpoint of Spent Fuel Pool temperature, and there 
  is still enough allowance, so that there is no problem.

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. 1.9m3/h 
  through reactor feed water system piping arrangement, and at approx. 
  6.1m3/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.

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 2:30 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.
- 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 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.
- On December 4, workers of partner companies found that there was puddle 
  water inside the barrier around the evaporative condensation apparatus. 
  Afterwards we stopped the apparatus, and workers made visual inspection 
  of the apparatus and confirmed the leakage have stopped. After conducting 
  investigation, we found a crack in the concrete barrier, and water 
  leaking from this crack to the gutter (surface dose rate of leaked water: 
  beta ray 110 mSv/h, gamma ray 1.8 mSv/h). We also found water leaking 
  from between the barrier and the base concrete. We are considering 
  measures to stop this leakage to outside of the barrier. We confirmed 
  that the leakage had stopped by piling up sandbags between the barrier 
  and base concrete, and in the gutter. We sent the leaked water remaining 
  in the barrier to the waste water RO supply tank with a water pump 
  (approx. 15 m3).
  Since the gutter led to the generally used channel of the power plant, 
  we have taken sea water from the channel around the water desalinations 
  (evaporative concentration apparatus) and the south drain (drain for the 
  generally used channel) and have conducted a nuclide analysis, and we 
  judged that the leaked water has been discharged into the sea from the 
  exit of generally used channel. It was estimated that approx. 150 liter 
  out of leakage water has flew in the channel, and assumed that it has 
  been discharged into the sea through the generally used channel. As a 
  result, the whole amount of radioactivity was approx. 2.6 x 1010 Bq 
  (temporary). As the impact of the discharge water into the sea, in the 
  assumption that we eat fish and seaweeds around the discharge channel 
  every day, the effective zone for an adult is approx. 0.0037 mSv / year, 
  that equals to approx. 1/600 of annual dose from nature for general 
  public (2.4 mSv), so that we evaluate there is almost no impact
- We plan to establish the system injecting water into the reactor in Unit 
  1 to 3 using the condensate storage tank of Unit 3. In preparation of 
  such establishment, the stored water in the tank was transferred to the 
  basement of turbine building of Unit 3 from 10:22 am on November 21 to 
  9:45 am on November 24. As the calibration of water level gauge is 
  required if all the water is transferred, approx. 200 ton was left in 
  the tank. During the measurement of salt concentration in the left water, 
  it turned out that concentration was high. In order to secure the space 
  for additional water injection to decrease such concentration, at 10:00 
  am on December 6, the left water was transferred from the tank to the 
  basement of the turbine building of Unit 3.
  At 8:54 on December 7, we stopped transferring, and at approx. 9:19 am 
  on the same day, we started filling water in the tank, but afterwards, 
  we confirmed water leakage (approx. 5 liter) at the joint section of 
  hose connecting to the tank, at approx. 9:52 am, we stopped filling water 
  and confirmed the leakage has stopped. We plan to consider such measures 
  as repair etc. in future. The leaked water was treated as to be free of 
  radioactive materials and desalinated. At 9:05 am on December 9, we 
  restarted filling the water in the tank after completing the replacement 
  of the transfer hose. 
- At 10:00 am on December 8, we started transferring accumulated water from 
  the Unit 6 turbine building to the temporary tank.
- At 9:28 am on December 9, the operation of facilities to cool the common 
  spent fuel pool was suspended in order to implement the replacement work 
  of power source for such facilities. The pool temperature at that time 
  was 18.8 degree C and expected increase would be 0.25 degree C/h. As 
  there exist enough buffers, there would be no major issue rising from 
  this operation.