*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 4.2m3/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.
- At 10:44 am on December 5 we started increasing nitrogen injection to 
  the reactor , from which we started on November 30 from approx. 5Nm3/h 
  to 10Nm3/h, due to stabilized parameters of the facilities of the power 
  plants such as the Reactor Pressure Vessel and the Primary Containment 
  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.
  Water is currently injected at approx. 3.1m3/h through reactor feed
  water system piping arrangement, and at approx. 4.3 m3/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.
- 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. 
  Water is currently injected at approx. 2 m3/h through reactor feed water
  system piping arrangement, and at approx. 6.1 m3/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.
- At 10:25 am on December 5 we started increasing nitrogen injection to 
  the reactor , from which we started on November 30 from approx. 5Nm3/h 
  to 10Nm3/h, due to stabilized parameters of the facilities of the power 
  plants such as the Reactor Pressure Vessel and the Primary Containment 
  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.
- From November 28, we started cleaning to avoid the performance
  deterioration of pumps by sucking up sands etc. accumulated at the
  bottom of the inlet canal pump room.
- 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.
- From 9:25 am on November 15 to 10:31 am on December 5, we transferred 
  accumulated water from the basement of the turbine building of unit 3 to
  the Centralized Radiation Waste Treatment Facility Building.
- 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 11:33 am on December 4, workers of cooperative company found that
  there was puddle water inside the barrier around the evaporative
  condensation apparatus (the estimated volume of water was approx. 45 m3).
  At 11:52 am, we stopped the evaporative condensation apparatus 3A, and
  at 12:14 pm, workers made visual inspection of the apparatus and the
  leakage seemed stopped. After that, we conducted investigation and at
  2:30 pm, we found that there is a crack in the barrier made of concrete,
  that water was leaking to the gutter (surface dose rate of leaked water:
  beta ray 110 mSv/h, gamma ray 1.8 mSv/h) and that leaked water was
  distilled through the gap between the barrier and base concrete. We are
  considering emergency response to stop leakage of water to the outside
  of the barrier. In the meantime, the water desalination apparatus
  (reverse osmosis membrane type) is continuing operation. As we have
  sufficient volume of desalinated water, there is no impact on the
  Reactor water injection. We piled sandbags around the gap and in the
  gutter and, at 3:30 pm, we confirmed the leakage was stopped. In
  addition, the accumulated water inside the barrier was transferred to
  waste liquid RO tank by under water pump etc. from 6:10 pm to 10:20 pm.
  Meanwhile, because the gutter is connected to general drainage canal in
  the power station, water in general drainage canal around the
  evaporative condensation apparatus and seawater around south discharge
  channel, which is located the exit of general drainage canal, was
  sampled. As a result of nuclide analysis, the result was similar extent
  of or slightly higher than the latest one of published daily analysis.
  On 5 December we again sampled the water of the channel near the water 
  desalination (evaporative concentration apparatus) and the south drain 
  (exit of the channel) and conducted a nuclide analysis, and the results 
  of the south drain showed the same level as the results we are 
  announcing daily. 
- At 10:00 am on December 5, accumulated water in the turbine building of
  Unit 6 was started to be transferred to a temporary tank.
- From 10:35 am to 12:05 pm on December 5, we implemented dust sampling 
  above the reactor building of Unit 3 using a large crane.