*The 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, 2011. It was assumed to be hydrogen
 explosion.
-At 3:37 pm on March 25, 2011, 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, 2011, 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 amount from the reactor feed water system is
 approx.4.4 m3/h and that from the core spray system is approx. 1.9 m3/h.
-At 1:31 am on April 7, 2011, we commenced injection of nitrogen gas into
 Primary Containment Vessel.
-At 11:22 am on August 10, 2011, 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, 2011, 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, 2011, we started operation to inject nitrogen
 into the reactor pressure vessel.
-At 6:00 pm on December 19, 2011, a full-scale operation of the PCV gas
 management system started.

Unit 2 (Shut down) 
-At approximately 6:00 am on March 15, 2011, an abnormal noise began
 emanating from nearby Pressure Suppression Chamber and the pressure
 within the chamber decreased. 
-At 10:10 am on March 26, 2011, 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, 2011, in addition to water injection from
 feed water system, we started water injection from piping of core spray
 system to the reactor. 
 Because the tendency of temperature rise at the bottom of PCV had been
 accelerated since February 2, we increased the amount of water injected
 to the reactor and continued monitoring the tendency of the temperature
 fluctuation. Since the temperature had remained high around 70.0 °C, we
 injected boric acid into the reactor as a safety countermeasures against
 the re-criticality from 0:19 am to 3:20 am on February 7, and changed the
 amount of the core spray system injection water from 3.7m3/h to 6.7m3/h at
 4:24 am (the amount of the continuing feed water system injection is
 6.8m3/h). Currently, the temperature is approx. 67.9°C (as of 5 am on 
 February 9). We will monitor the progress continuously. 
 At 9:47 am February 9, as the amount of water injection decrease, we 
 adjusted the volume from the feed water system of reactor Unit 2 
 increased from approx. 6.4 m3/h to approx. 6.8 m3/h(the amount of the 
 continuing injection from reactor core spray system is approx. 6.8 m3/h. 
 The current water injection amount from the reactor feed water system is
 approx. 6.8 m3/h and that from the core spray system is approx. 6.8 m3/h.
-At 5:21 pm on May 31, 2011, 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, 2011, we started injecting nitrogen gas into the
 Primary Containment Vessel.
-At 6:00 pm on October 28, 2011, a full-scale operation of the PCV gas
 control system started. 
-At 10:46 am on December 1, 2011, we started the nitrogen injection to the
 Reactor Pressure Vessel.
-At 11:50 am on January 19, 2012, we started the operation of the spent
 fuel pool desalting facility.

Unit 3 (Shut down) 
-Explosive sound and white smoke were confirmed at approximately 11:01 am
 on March 14, 2011. It was assumed to be hydrogen explosion.
-At 6:02 pm on March 25, 2011, 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, 2011, 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 amount from the reactor feed water system is
 approx. 2.8 m3/h and that from the core spray system is approx. 5.8m3/h.
 At 7:47 pm on June 30, 2011, 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, 2011, injection of nitrogen gas into the Primary
 Containment Vessel started. 
-At 4:26 pm on November 30, 2011, we started operation to inject nitrogen
 into the reactor pressure vessel.
-At 3:18 pm on January 14, we started operation of the radioactive
 material removal instrument for the spent fuel pool in Unit 3

Unit 4 (Outage due to regular inspection) 
-At around 6 am on March 15, 2011, 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, 2011, 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, 2011, 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, 2011, we started the Residual Heat Removal System
 Pump in order to cool the spent fuel pool.
-At 2:45 pm on July 15, 2011, 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, 2011, 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, 2011, we started the Residual Heat Removal
 System Pump of Unit 6 to cool down Spent Fuel Pool.
-At 2:33 pm on September 15, 2011, 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 10:00 am on June 13, 2011, 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, 2011, 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, 2011, 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, 2011, 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, 2011, 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, 2011, we started the re-circulating operation
 of desalination facility (reverse osmosis membrane type) for the purpose
 of suppression of condensed water after desalination treatment.
-As finding of accumulated water containing radioactive materials at the
 trench between the Process Main Building and the Miscellaneous Solid
 Waste Volume Reduction Treatment Building [High Temperature Incinerator
 Building] (December 18, 2011), we started the inspection of other
 trenches at the site on January 11.
-As a result of the inspection made on February 8, the preliminary results 
 of the nuclide analysis and executed place are as follows: 
·Inside the duct for power cables for the Unit 6 water intake 
  I-131: below the detectible limit, Cs-134: 1.0x10-1 Bq/cm3, Cs-137: 
  8.3x10-2 Bq/cm3 
·Inside the trench for the Unit 5 and 6 storm drain pipes 
  I-131: below the detectible limit, Cs-134: 1.7x10-1 Bq/cm3, Cs-137:  
  2.5x10-1 Bq/cm3 
·Inside the duct for the Unit 5 radioactive fluid pipes 
  I-131: below the detectible limit, Cs-134: 8.0x10-2 Bq/cm3, Cs-137: 
  1.3x10-1 Bq/cm3 
·Inside the duct for the Unit 6 main transformer cables 
  I-131: below the detectible limit, Cs-134: 2.8x10-1 Bq/cm3, Cs-137: 
  4.3x10-1 Bq/cm3 
·Inside the trench for heavy oil pipes (east of Unit 5) 
  I-131: below the detectible limit, Cs-134: 2.0x10-1 Bq/cm3, Cs-137: 
  2.8x10-1 Bq/cm3 
-At 9:18 am on January 31, we started transfer of Sub-drain Water of Unit
 6 to the temporary tank. We will conduct transferring to the temporary
 tank appropriately.
-At 2:14 pm on February 7, 2012, we started transferring the accumulated
 water from the basement of turbine building of Unit 2 to Centralized
 Radiation Waste Treatment Facility (Miscellaneous Solid Waste Volume
 Reduction Treatment Building [High Temperature Incinerator Building]).
-From At 10:00 am to 4:00 pm on February 8, 2012, we transferred the
 accumulated water from inside the turbine building of Unit 6 to the
 temporary tank.
-At 10:00 am on February 9, 2012, we started transferring the accumulated 
 water from the turbine building of Unit 6 to the temporary tank.

* In the Chapter 12 of Nuclear Reactor Facilities Security Regulation "The
  Way of Ensuring Mid-term Security", as the treatments like "Operational
  limitation" or "Measures required in case of not satisfying the
  operational limitation" are determined, it is supposed the operator act
  per the required measures if it fails to satisfy the operational
  limitation. This time, to implement maintenance works, we changed the
  amount of water injection into Unit 2 (from 3:48 am on February 7 to
  6:48 pm on February 8) by conducting a planned shift beyond the range of
  operational limitation.