*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 4.5m3/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. 

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. 4.5 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. 

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. 6.0 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 2:00 am on November 27, we confirmed the difference in temperature at 
  the gateway of the heat exchanger on the primary side of the spent fuel 
  pool alternative cooling equipment was getting small (inlet 
  temperature: 19.7°C, outlet temperature: 19.0°C). However, as we could 
  figure out that it did not affect the cooling of the spent fuel pool 
  immediately, we decided to conduct a field investigation after dawn. At 
  6:33 am, as a result of the field investigation, we confirmed the main 
  valve of watering equipment was closed and therefore we opened it and 
  filled with water for watering. As a result, we could confirm that the 
  outlet temperature fell down (as of 7:00 am on November 27, inlet 
  temperature: 20.3°C, outlet temperature: 15.1°C). Considering this 
  result, it is confirmed that the cause for the difference in temperature 
  is that the valve was closed down and the cooling water was not supplied. 
  We will further investigate the reason of the closing down of the valve 
  (the temperature of the inlet port of the heat exchanger on the primary 
  side = the temperature of the spent fuel pool).  
- 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.
- 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.
- From 2:54 pm on November 25 to 9:38 am on November 27, we transferred 
  the accumulated water from basement of Unit 1 turbine building to
  basement of Unit 2 turbine building.