*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.
 The current water injection volume is approx. 4.3 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.
-At 6:00 pm on December 19, a full-scale operation of the PCV gas 
 management system started.

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, in addition to water injection from water 
 feeding system, we started water injection from piping of core spray 
 system to the reactor.
 The current water injection volume is approx. 1.9 m3/h from the reactor 
 feed water system and approx. 7.0 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 1:36 pm to 3:12 pm on December 26, we 
 also started to inject hydrazine [corrosion inhibitor]).
 At 1:58 pm on December 27, in the alternative cooling system of the spent 
 fuel pool of Unit 2, as the inhale pressure of the primary circulating 
 pump showed the tendency of decrease, we stopped the pump in order to 
 conduct flushing of the strainer on its entry side and suspended cooling 
 of the spent fuel pool (the temperature of the pool at the time of the 
 suspension was approx. 14.2°C). After the flushing, we are maintaining 
 the inhale pressure of the primary circulating pump. Therefore, at 3:57 
 pm on the same day we resumed the pump and cooling of the spent fuel pool 
 (the temperature of the pool at the time of the resuming was approx. 14.2
 °C).
-At 8:06 pm on June 28, we started injecting nitrogen gas into the Primary 
 Containment Vessel.
-At 6:00 pm on October 28, we put the gas management system of the reactor 
 containment vessel in operation. On December 28, we sampled gases in gas 
 management system in primary containment vessel of Unit 2 to analyze 
 nuclides. As a result of nuclides analysis, we evaluated that there is no 
 recriticality since the density of Xe-135 is below the detection limits 
 (1.1x10-1 Bq/cm3) and that indicates the analyzed figure is below the 
 determination criteria for recriticality such as 1 Bq/cm3.
-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. 
 The current water injection volume is approx 3 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. (From 1:28 pm to 3:07 pm on December 28, we 
 conducted injection of hydrazine to spent fuel pool of Unit 4 through the 
 circulating cooling 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 2:45 pm on July 15, we started the operation of the original Residual 
 Heat Removal System (System B) by its original seawater pump.
-At 10:11 am on December 22, since we finished the recovery work of 
 seawater pump (System B) of equipment water cooling system, we made a 
 trial run. At 11:25 am on the same day, we confirmed no abnormalities and 
 restarted the operation.
-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 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 12:25 pm on December 13, we started the re-circulating operation of 
 desalination facility (reverse osmosis membrane type) for the purpose of 
 suppression of condensed water after desalination treatment.
-Since December 22, one of the atmospheric temperatures of Unit 1 Primary 
 Containment Vessel (PCV) monitored by the Containment Atmospheric 
 Monitoring System had risen (the atmospheric temperature of the PCV on 
 December 22 was approx. 38°C, at 7 pm on December 27 was approx. 49°C). 
 The other temperatures had not risen, so we conducted a survey from 9 am 
 to 10 am on December 28, and we confirmed that there are no problems. 
 From 11:00am to 12:15pm on the same date, to identify cause with 
 monitoring, we adjusted the volume of Nitrogen injection, from approx. 8 
 m3/h to approx.18 m3/h, and emission of the gas management system, from 
 approx. 23 m3/h to approx.30 m3/h, as of before December 22. The 
 temperature, the maximum went up to approx. 54.6°C at 6 pm on December 28, 
 fell to approx. 52.3°C at 10 am on December 29. We are planning to 
 identify cause with monitoring. 
-At 3:22 pm on December 28, we started to transfer accumulated water from 
 the basement of turbine building of Unit 2 to the Centralized Radiation 
 Waste Treatment Facility (Miscellaneous Solid Waste Volume Reduction 
 Treatment Building [High Temperature Incinerator Building] and the 
 Process Main Building). 
-At 3:32 pm on December 28, we started to transfer accumulated water from 
 the basement of turbine building of Unit 3 to the Centralized Radiation 
 Waste Treatment Facility (Miscellaneous Solid Waste Volume Reduction 
 Treatment Building [High Temperature Incinerator Building] and the 
 Process Main Building). At 9:03 am on December 29, we stopped transfer.