*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 4.4m3/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. 

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.
- As of 5:00 pm on November 26, the indicator of the gas temperature of 
  Suppression Chamber read 52.7°C, but at 11:00 pm on the day we confirmed 
  that it read "Overscaled" (digital recorder). Then, as of 5:00 am on 
  November 27, it read 102.6°C. Though the readings were not stable, as 
  there were no significant changes or variations in the temperatures of 
  the same types of 2 thermometers and the pool water in Suppression 
  Chamber, we have been investigating the causes for this event including 
  the possibility of malfunction of the measuring instruments.
  Later, we inspected the measuring instruments and estimated that the 
  readings were overscaled due to certain impacts on the signal detection 
  line seeing that signal from the temperature detector is not stable. We 
  will keep monitoring readings of this instrument and also monitor the 
  temperature using instruments close to it. 
- The indicator for the inside of the Primary Containment Vessel (Drywell) 
  of Unit 2 (base line temperature of the air conditioning unit, local 
  cooling equipment) read 78.2°C as of 5:00 am on November 27 but at 6:50 
  am on the day it was confirmed that it read approximately 84°C, 
  increasing in a staircase pattern. On the other hand, it was also 
  confirmed that the temperature changes of the bottom of the Reactor 
  Pressure Vessel and the water in the pool of the Suppression Chamber 
  were smaller than that of the inside of the Primary Containment Vessel 
  (Drywell) and that there was no significant change in the temperature.
  Since we have been decreasing the flow rate of water injection as stated 
  below, it is expected that the temperature inside the Primary 
  Containment Vessel will rise. However, as the line temperature of which 
  rose in a staircase pattern was only one line of the five lines and the 
  rest of the lines did not show the same changes, we have been 
  investigating the causes for this event, including the possibility of 
  malfunction of the measuring instruments. 
  Later we inspected the instrument but got no data indicating malfunction, 
  and the readings after the inspection are not different from those 
  before. Therefore, we estimated that the signal detection line was 
  somehow affected, which raised the temperature indicated. We will keep 
  monitoring this instrument and also monitor the temperature using 
  instruments close to it. 
  ·At 7:11 pm on November 24, we adjusted the flow rate of water 
   injection from Core Spray System from approx. 7.2 m3/h to approx. 
   5.6m3/h (for feed water system, the flow rate is kept at 2.9 m3/h).
  ·On November 26 (from 10:18 am to 11:02 am), we adjusted the flow rate 
   from Core Spray System from approx. 5.5 m3/h to approx. 4.5m3/h (for 
   feed water system, the flow rate is kept at 3.0 m3/h).
- At 9:12 am on November 28, the alarm went off indicating that the 
  difference of flow rates between at the entrance and at the exit of the 
  primary pump of the alternative cooling system for the spent fuel pool, 
  and the system automatically stopped. At 9:16 am on the same day we 
  checked the site and no leakage was confirmed. We are investigating the 
  cause. 

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. 1.9 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. 

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 11:34 am on August 20, we started an operation of desalination 
  equipment in the spent fuel pool.
- 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.