*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.
- From 3:37 pm on March 25, we started injecting freshwater by a motor 
  driven pump which is now powered by the off-site transmission line.
  Water is currently injected at approx. 3.6 m3/h through reactor feed 
  water system piping arrangement. 
- 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. 

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. 
- From 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.
  At 3:05 pm on September 26, the amount of water injection from the core 
  spray system into the reactor was adjusted from approx. 5.0 m3/h to 
  approx. 6.0 m3/h. 
  Water is currently injected at approx. 4.0 m3/h through reactor feed 
  water system piping arrangement, and at approx. 6.0 m3/h through core 
  spray system water injection piping arrangement.
- From 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. 

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.
- From 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.
- From 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. 2.7 m3/h through reactor feed 
  water system piping arrangement, and at approx. 7.9 m3/h through core 
  spray system water injection piping arrangement.
- From 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.
- From 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.
- From 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.
- From 9:45 am to 10:42 am on September 26, we switched the seawater pump 
  from B system (permanently installed) to A system (temporarily installed) 
  in order to repair the outlet valve of Unit 5 residual heat removal 
  system seawater pump (D).  
- At this time, 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 time, we don't think there is any reactor coolant leakage inside 
  the primary containment vessel. 

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 8:00 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 9:51 am on September 13, we started transferring accumulated water 
  from the turbine building of Unit 2 to High Temperature Incinerator 
  Building of Centralized Radiation Waste Treatment Facility. 
- At 9:54 am on September 15, we started transfer of the accumulated water 
  from the turbine building of Unit 3 to Centralized Radiation Waste 
  Treatment Facility.
- At 8:30 pm on September 24, the 2nd Cesium adsorption apparatus of water 
  treatment facility has automatically shut down. Investigations are now 
  underway. Water injection of Unit 1 to 3 are continuing and as there are 
  sufficient treated water stored in the tank, there is no impact on the 
  water injection into the reactors. After that, we identified that the 
  cause of the shutdown was closure of a valve in the system due to 
  malfunction of an air compressor for valve actuators. After replacing the 
  compressor, at 5:02 pm on September 25, we restarted the 2nd Cesium 
  absorption apparatus and at 5:05 pm, reached the rated flow.
- At 10:00 am on September 26, we started transfer of the accumulated water 
  from the turbine building of Unit 6 to the temporary tank.
- One of the staff from the cooperating companies was injured catching his 
  forth finger between the steel stocks in site of the power plant 
  (outdoors) at 11:05 am, September 26. The staff returned to the office 
  outside the site and was carried to the emergency medical office of Unit 
  5 & 6 with a surgical mask on, not the full-cover mask. We are planning 
  to conduct a measurement with a whole body counter just in case. 
  Contamination on the surface of the body and the surgical mask is not 
  detected.