*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 10:11 am on December 10, in addition to water injection from water
 feeding system, we started water injection from piping of core spray
 system to the reactor. At 10:30 am on December 11th, we adjusted water 
 injection from Core Spray System from approx. 1.0 m3/h to approx. 2.0 
 m3/h to cool down the reactor more safely. 
 The current water injection volume is approx 4.2 m3/h from the reactor
 feed water system and approx. 2 m3/h from the core spray 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. At 10:44 am on December 11th, we adjusted water injection 
 from Core Spray System from approx. 5.6 m3/h to approx. 6.0 m3/h to cool 
 down the reactor more safely, while we adjusted water injection from the 
 Feed Water System from approx. 2.5 m3/h to approx. 3.0 m3/h 
 The current water injection volume is approx 3.0 m3/h from the reactor
 feed water system and approx. 6.0 m3/h from the core spray system.
-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 10:46 am on December 1, we started the nitrogen injection to the
 Reactor Pressure 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.
-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 11:10 am on December 11th, as we found that there was small vibration 
 at the Flow Control Valve of Core Spray System, we adjusted water 
 injection from Core Spray System to unit 3 from approx. 6.1 m3/h to 
 approx. 6.5 m3/h, while we adjusted water injection from the Feed Water 
 System from approx. 3.1 m3/h to approx. 2.5 m3/h. Because the vibration 
 of the Flow Control Valve still continued, we adjusted water injection 
 from the Feed Water System to approx. 3.0 m3/h, and from Core Spray 
 System to approx. 6.0 m3/h. Because the vibration is tiny and would do 
 little influence on pipe arrangements and others, we will study on its 
 countermeasure later. 
 The current water injection volume is approx 3.0 m3/h from the reactor
 feed water system and approx. 6 m3/h from the core spray system.
-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.
-At 10:58 am on November 29, in order to decrease more salinity, we
 installed Ion exchange equipment and started the operation of such
 equipment.
-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 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 2:00 pm on December 10, we started transferring of accumulated water
 from underground of the Turbine Building of Unit 1 to underground of the
 Turbine Building of Unit 2.