*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 5:47 pm on 5 December, Amount of water injected through feed water 
  system was adjusted from approx. 4.0 m3/h to 4.5 m3/h. as the decrease 
  of such amount was observed. 
  The current water injection volume is approx 4.5m3/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.

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. 4.2m3/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.
- 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. After its continuous 
  operation for a month, the concentration of radioactive materials is 
  expected to go below the level of 102, the facilities finished its 
  operation on December 5. Sampling analysis of water in the spent fuel 
  pool thereafter confirmed that the concentration of radioactive material 
  actually decreased to the level of 102 from the level of 105 before the 
  removal operation. 
- At 10:46 am on December 1, we started the nitrogen injection to the 
  Reactor Pressure Vessel.
- At 8:25 am on 6 December, dust sampling at opening part (blow out panel) 
  of Reactor Building in Unit 2 was started. At 10:25 am, the dust 
  sampling was completed.

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. 
  At 5:47 pm on 5 December, Amount of water injected through feed water 
  system was adjusted from approx. 2.0 m3/h to 2.2 m3/h. as the decrease 
  of such amount was observed. Water is currently injected at approx. 
  2.1 m3/h through reactor feed water system piping arrangement, and at 
  approx. 6.0 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.

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, for the purpose of the cleaning by sucking up sands 
  etc. accumulated at the bottom of the inlet canal pump room in order to 
  avoid the performance deterioration of pumps, we stopped the pump (D) of 
  the residual heat removal system and suspended cooling the reactor, We 
  also stopped the pump (C) of the cooling water system and suspended 
  cooling the spent fuel pool. When each pump was stopped, the 
  temperatures of the water in the reactor and the spent fuel pool were 
  25.7°C and 20.4°C respectively. The planned suspension of cooling is 
  between 7:00 am to 5:00 pm everyday, and the temperature increases of 
  the water in the reactor and the spent fuel pool due to the suspension 
  are expected to be approx. 17°C and approx. 4°C per day respectively (we 
  plan to do the cleaning work for approx. 1 week).
  On December 6, after the completion of such cleaning work, at 2:06 pm, 
  we reactivated the pump (C) of the cooling water system in Unit 5 in 
  order to restart the cooling of the spent fuel pool.(The temperature of 
  the spent fuel pool was 23.3°C). At 2:24 pm, we reactivated the pump (D) 
  of the residual heat removal system in Unit 5 in order to restart the 
  cooling of the spent fuel pool.(The temperature of the spent fuel pool 
  was 35°C). 
- 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.
- At 11:33 am on December 4, workers of cooperative company found that 
  there was puddle water inside the barrier around the evaporative 
  condensation apparatus (the estimated volume of water was approx. 45 m3). 
  At 11:52 am, we stopped the evaporative condensation apparatus 3A, and 
  at 12:14 pm, workers made visual inspection of the apparatus and the 
  leakage seemed stopped. After that, we conducted investigation and at 
  2:30 pm, we found that there is a crack in the barrier made of concrete, 
  that water was leaking to the gutter (surface dose rate of leaked water: 
  beta ray 110 mSv/h, gamma ray 1.8 mSv/h) and that leaked water was 
  distilled through the gap between the barrier and base concrete. We are 
  considering emergency response to stop leakage of water to the outside 
  of the barrier. In the meantime, the water desalination apparatus 
  (reverse osmosis membrane type) is continuing operation. As we have 
  sufficient volume of desalinated water, there is no impact on the 
  Reactor water injection. We piled sandbags around the gap and in the 
  gutter and, at 3:30 pm, we confirmed the leakage was stopped. In 
  addition, the accumulated water inside the barrier was transferred to 
  waste liquid RO tank by under water pump etc. from 6:10 pm to 10:20 pm. 
  Meanwhile, because the gutter is connected to general drainage canal in 
  the power station, water in general drainage canal around the 
  evaporative condensation apparatus and seawater around south discharge 
  channel, which is located the exit of general drainage canal, was 
  sampled. As a result of nuclide analysis, the result was similar extent 
  of or slightly higher than the latest one of published daily analysis. 
  On 5 December we again sampled the water of the channel near the water 
  desalination (evaporative concentration apparatus) and the south drain 
  (exit of the channel) and conducted a nuclide analysis, and the results 
  of the south drain showed the same level as the results we are 
  announcing daily.
- At 10:00 am on December 5, accumulated water in the turbine building of 
  Unit 6 was started to be transferred to a temporary tank. At 4:00 pm on 
  December 6, the transfer was stopped. 
- 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 approx. 11:00 am on December 6, leakage at a pin hole on the transfer 
  hose from a buffer tank to a desalination facility (leakage was a drop 
  per second). It was confirmed that leakage stopped after the temporary 
  repair with the water proof tape. The impact on the environment is 
  minimal as the leaked water is desalinated after the treatment by the 
  radioactive material removal facility and the leaked amount is little 
- At 0:20 pm on December 6, it was confirmed that the measurement data for 
  0:00 pm in the monitoring post set at the main gate was missing. The 
  data for 1:00 pm, 1:30 pm, and 2:00 pm were manually measured at the 
  location and the measured data was in the same level as the data before 
  0:00 pm. Thereafter, we have removed the water accumulated in the cable 
  connector portion of the monitoring post and restarted the measurement 
  by the monitoring post at 2:30 pm. 
- At 5:48 pm on December 3, the display malfunction of the No.8 monitoring 
  post measuring the radiation dose in the site was observed. As we could 
  not identify the cause and thus not make repair, alternative measurement 
  was conducted by the dosimeter located near the No.7 and 8 monitoring 
  post, which was installed to reinforce the surveillance along with the 
  nitrogen injection operation into the Reactor Pressure Vessel. Measured 
  data indicates no change from the previous day (No.7 monitoring post: 
  92μSv/h, No. 8 monitoring post: 42μSv/h as of 8:00 am)
  On December 6, the display function of No. 8 monitoring post was 
  retrieved when its board was reinserted. 
  Thereafter, we have restarted the measurement with No. 8 monitoring post 
  as no sign of reoccurrence was confirmed.