* 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.4.6 m3/h and that from  the core spray system is approx. 2 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. 
  To improve reliability of water injection to the reactors, the injection 
  line connecting to the reactor injection pump on the hill was replaced 
  with polyethylene pipes and we have been changing the route for reactor 
  injection from feed water system to reactor core spray system in a 
  stepwise manner. After completion of adjusting water flow amount as 
  planned on February 2, tendency of temperature rise at the bottom of PCV 
  was observed. Thus, at 7:20 pm on February 3, 2012, we changed the 
  injection amount into Unit 2 reactor through feed water system from 
  approx. 2.9 m3/h to approx. 4.9 m3/h and changed that though reactor 
  core spray system from approx. 5.8 m3/h to approx. 3.8 m3/h (which means 
  setting them at those of before flow adjustment on February 1, 2012). 
  After that, we have observed the tendency of temperature at the upper 
  head of the bottom of PCV. The temperature was around 70.0 °C (approx. 
  70.3 °C at 11:00 pm on February 5) and in order to prevent further 
  temperature increase, we decided to increase the amount of water injected 
  to the reactor. At 1:29 pm on February 6, the water injection volume to 
  the Unit 2 reactor through the feed water system was changed from approx. 
  5.8 m3/h to approx. 6.8 m3/h (the water injection through the reactor 
  core spray system remains approx. 3.8 m3/h). At this moment, temperature 
  indicates approx. 70.6 °C (as of 5:00 am on February 6). We will monitor 
  it continuously.
  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. 3.8 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 
  management 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.
  At 10:56 pm on February 4, "Abnormal state (low pressures) in suction 
  pressure of RO high pressure pump" triggered the alarm in the desalting 
  facility for spent fuel pool of Unit 2, and the facility automatically 
  stopped. Because all isolation valves of the system have been closed due 
  to the interlock and the alternative cooling system for spent fuel pool 
  is continuously operated, it does not affect the cooling for the spent 
  fuel pool. In addition, as a result of site check, it was confirmed that 
  any leakage from the facility was not found. At 5:35 pm of February 5, 
  the operation of the system was resumed and no abnormality was confirmed. 
  Also, there was no abnormality regarding the RO high pressure pump. We 
  will monitor it continuously.

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. 2.9 m3/h and that from the core spray system is approx. 6m3/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. (From 1:24 pm to 3:07 pm on February 3, 
  2012, we injected hydrazine [corrosion inhibitor].)
  Regarding the water leakage from Filtrate water supply valve of spent 
  fuel pool cooling system occurred on January 29,we removed the valve and 
  completed installation of blanking plate, In addition, we are temporally 
  suspending the secondary cooling tower in order to prevent overcooling 
  of spent fuel pool alternative cooling facility. Because the pool 
  temperature began to increase, at 9:55 am on February 6, we initiated 
  the secondary cooling tower. 
- 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.
- At 4:07 pm on February 3 to 8:47 am on February 6, 2012, we transferred 
  accumulated water from the basement of T/B, Unit 2 to the Centralized 
  Waste Treatment Facility (Miscellaneous Solid Waste Volume Reduction 
  Treatment Building [High Temperature Incinerator Building] and Process 
  Main Building). 
- 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 9:49 am on February 5, we started water transfer from the basement of 
  turbine building of Unit 3 to Centralized Radiation Waste Treatment 
  Facility (Miscellaneous Solid Waste Volume Reduction Treatment Building 
  [High Temperature Incinerator Building]).
- At 10:00 am on February 6, we started water transfer from the basement 
  of turbine building of Unit 6 to the temporary tank. 
- At 8:40 am on February 6, we temporally suspended the second cesium 
  adsorption apparatus to conduct backwash of the filter since gradual 
  decrease in the volume of treatment was confirmed. 
- At 8:05 am on February 5, our employee on patrol confirmed the water 
  leakage from valve flange in the outdoor fire protection system piping 
  in Unit 6. Around 8:31 pm, the valve for upper stream was closed and 
  leakage was stopped. The water leaked was already processed and there 
  supposed to be no outflow of the water to the sea because there is no 
  drain located near by.