*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 4.3m3/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.
-At 4:04 pm on November 30, we started operation to inject nitrogen into
 the reactor pressure vessel.
-On December 7, as a part of installation work of the Primary Containment
 Vessel Gas Management System in the Unit 1 reactor building, we conducted
 nitrogen substitution in order to eliminate hydrogen in the existing pipe
 arrangement to be used in the 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. 
-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. 3m3/h through reactor feed water
 system piping arrangement, and at approx. 4.1m3/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. On December 5, the
 facilities finished its operation.
-At 10:46 am on December 1, we started the nitrogen injection to the
 Reactor Pressure Vessel.
-At 4:17 am on December. 7, on the alternative Spent Fuel Pool cooling
 system of Unit 2, the alarm indicating that the difference of flow rates
 between at the entering and at the exit of the primary pump is big went
 off, and the system stopped automatically. At 4:41 on the same day, after
 field investigation, no defect such as leakage was confirmed. Currently
 the cause is under investigation,. At 4:00 am, the temperature of Spent
 Fuel Pool was 18.4 degree C, the assumed increase of temperature is 0.3
 degree C/h, from the viewpoint of Spent Fuel Pool temperature, there is
 still enough allowance, so that there is no problem.

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. 2m3/h through
 reactor feed water system piping arrangement, and at approx. 6.1m3/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 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.
-Regarding spent fuel pool for unit 4, from August 20 to November 8, we
 had decreased salinity by using the desalting facility. In order to
 decrease more salinity, we installed Ion exchange equipment and started
 the equipment at 10:58 am on November 29.
-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.
-On December 4, workers of partner companies found that there was puddle
 water inside the barrier around the evaporative condensation apparatus.
 Afterwards we stopped the apparatus, and workers made visual inspection
 of the apparatus and confirmed the leakage have stopped. After conducting
 investigation, we found a crack in the concrete barrier, and water
 leaking from this crack to the gutter (surface dose rate of leaked water:
 beta ray 110 mSv/h, gamma ray 1.8 mSv/h). We also found water leaking
 from between the barrier and the base concrete. We are considering
 measures to stop this leakage to outside of the barrier. We confirmed
 that the leakage had stopped by piling up sandbags between the barrier
 and base concrete, and in the gutter. We sent the leaked water remaining
 in the barrier to the waste water RO supply tank with a water pump
 (approx. 15 m3).
 Since the gutter led to the generally used channel of the power plant, we
 have taken sea water from the channel around the water desalinations
 (evaporative concentration apparatus) and the south drain (drain for the
 generally used channel) and have conducted a nuclide analysis, and we
 judged that the leaked water has been discharged into the sea from the
 exit of generally used channel. It was estimated that approx. 150 liter
 out of leakage water has flew in the channel, and assumed that it has
 been discharged into the sea through the generally used channel. As a
 result, the whole amount of radioactivity was approx. 2.6 x 1010 Bq
 (temporary). As the impact of the discharge water into the sea, in the
 assumption that we eat fish and seaweeds around the discharge channel
 every day, the effective zone for an adult is approx. 0.0037 mSv / year,
 that equals to approx. 1/600 of annual dose from nature for general
 public (2.4 mSv), so that we evaluate there is almost no impact
-We plan to establish the system injecting water into the reactor in Unit
 1 to 3 using the condensate storage tank of Unit 3. In preparation of
 such establishment, the stored water in the tank was transferred to the
 basement of turbine building of Unit 3 from 10:22 am on November 21 to
 9:45 am on November 24. As the calibration of water level gauge is
 required if all the water is transferred, approx. 200 ton was left in the
 tank. During the measurement of salt concentration in the left water, it
 turned out that concentration was high. In order to secure the space for
 additional water injection to decrease such concentration, at 10:00 am on
 December 6, the left water was transferred from the tank to the basement
 of the turbine building of Unit 3.
 At 8:54 on December 7, we stopped transferring, and at approx. 9:19 am on
 the same day, we started filling water in the tank, but afterwards, we
 confirmed water leakage (approx. 5 liter) at the joint section of horse
 connecting to the tank, at approx. 9:52 am, we stopped filling water and
 confirmed the leakage has stopped. We plan to consider such measures as
 repair etc. in future. The leaked water was treated as to be free of
 radioactive materials and desalinated.  
-At 10:00 am on December 8, we started transferring accumulated water from 
 the Unit 6 turbine building to the temporary tank.