*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 10:18 am on November 29, since we observed decrease in water injection 
  into the reactor, we adjusted the water injection amount 4.2m3/h to 4.5m3/h 
  from feed water system. 
  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.
- In order to construct the nitrogen injection line direct to the reactor 
  branched by the nitrogen injection line into the primary containment 
  vessel, at 9:55 am on November 29, we temporarily stopped Nitrogen 
  injection into the primary containment vessel. Then, we restarted 
  Nitrogen injection into the primary containment vessel. At 11:30 am on 
  the same date, we confirmed the nitrogen injection amount (28Nm3/h) into 
  the primary containment vessel was stable. 

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. 4.4 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 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 9:12 am on November 28, the alarm indicating that the difference of 
  flow rates between at the entering and the exit of the primary pump at 
  the alternative cooling system for the spent fuel pool is big went off, 
  and the system automatically stopped. At 9:16 am on the same date, we 
  checked the site and no abnormality such as leakage was confirmed. Then, 
  considered the cause is stuck of dust in the pipe of flow sensor from 
  the investigation result, at 11:50 am on November 29, we started the 
  system and flushed. Then, we confirmed the flow sensor was operating 
  normally. We will monitor the status of the system operation. 
- In order to construct the nitrogen injection line direct to the reactor 
  branched by the nitrogen injection line into the primary containment 
  vessel, at 1:47 pm on November 29, we temporarily stopped nitrogen 
  injection into the primary containment vessel of Unit 2. Then, we 
  restarted Nitrogen injection into the primary containment vessel of Unit 
  2. At 2:37 pm on the same date, we confirmed the nitrogen injection 
  amount (26Nm3/h) into the primary containment vessel was stable. 

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 10:28 am on November 29, since we observed decrease in water injection 
  into the reactor, we adjusted the water injection amount 1.9m3/h to 2.1m3/h 
  from feed water system. 
  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 9:24 am on November 29, we started sampling of dusts at the upper 
  part of reactor building of unit 3 using a large crane vehicle. At 1:00 
  pm on the same date, we finished the sampling. 
- At 12:30 pm on November 29, we started dust sampling by using a robot 
  near the opening section for equipment hatch and truck bay door of Unit 
  1 Reactor building. At 1:00 pm on the same date, we finished the sampling. 

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.
- Starting on November 28, for the purpose of cleaning to avoid the 
  performance deterioration of pumps by sucking up sands etc. accumulated 
  at the bottom of the inlet canal pump room, we stopped the pump (D) of 
  the residual heat removal system thus suspended cooling the reactor, and 
  also stopped the pump (C) of the cooling water system thus 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 from 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 will be approx. 17°C and 
  approx. 4°C per day respectively (we plan to do the cleaning work for 
  approx. 1 week).
- 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 9:10 am on November 10, we started transfer of accumulated water from 
  the basement of Unit 2 turbine building to Centralized Radiation Waste 
  Treatment Facility High Temperature Incinerator Building.
- 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 approx. 2:28 pm on November 28, the alarm went off from an indicator 
  (continuous dust monitor) installed in front of Main Anti-Earthquake 
  Building to measure airborne radiation dose continuously. In response to 
  the alarm, we instructed to put full face masks on at 2:38 pm according 
  to the operation procedure. We are measuring the airborne radiation dose 
  in front of Main Anti-Earthquake Building, and investigating the cause 
  of the alarm. 
  We confirmed that there are no significant changes in the readings of 
  the monitoring posts. 
  At 2:50 pm on the same date, we replaced the filter of the monitor, and 
  restarted by reset operation. From the result of the airborne radiation 
  dose measurement in front of Main Anti-Earthquake Building, the airborne 
  radiation dose in front of Main Anti-Earthquake building was less than 
  detection threshold (7.34 x 10-6 [Bq/cm3]), which was less than the 
  reference measure for wearing a full face mask, 1 x 10-4[Bq/cm3]. At 4:04 
  pm on the same date, it was announced that the workers did not have to 
  wear a full face mask as per normal.
- At 12:30 pm on November 28, water leakage from pin holes at the pipe 
  arrangement between the water desalination facility and the buffer tanks 
  was detected at the different location from previous water leak, which 
  was detected on November 25. Then the replacement work was conducted. 
  Approx. at 3:40 pm, the water leakage from pin holes at another pipe was 
  detected. At the same time, water leakage was stopped by tapes. The pipe 
  will be also replaced. In addition, there is no influence to the water 
  injection into the reactor due to enough desalination water. And, we 
  confirmed the radiation dose in ambient air near the leaking point was 
  not specifically different from surrounding area.
- At 10:00 am on November 29, we started transfer of accumulated water 
  from Unit 6 turbine building to temporary tank.
- At 12:06 pm on November 29, we observed water leakage from a pin hole at 
  the pipe arrangement between the water desalination facility an the 
  buffer tanks (the leakage amount : approximately 500cc). then, we 
  replaced the pipes and confirmed the leakage was stopped. In addition, 
  there is no influence to the water injection into the reactor due to 
  enough desalination water.