* Updates from previous press release 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. 4.7 m3/h and that from the core spray system is approx. 1.7 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. 
  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. 6 m3/h.
- With regard to the water injection volume for Unit 2 reactor, which was 
  increased with temperature figure raising, we have gradually adjusted it 
  to the original volume before temperature increasing (Feed water system: 
  approx. 3.0m3/h, core spray system: approx. 6.0m3/h). During our observing 
  the plant parameter after decreasing the flow rate of feed water system 
  on February 22, we found that one thermometer in the lower part of the 
  RPV (top of the lower head 135°) indicated the different movement from 
  others. From 12:21 pm to 2:48 pm on February 23, we investigated the 
  concerned device. As the result of the measurement of DC resistance, we 
  found no breaking wire and availability of the thermometer. But we 
  confirmed that the DC resistance of it became higher than the previous 
  measurement test data. We will evaluate the soundness of the concerned 
  device and examine correspondence in future. We make sure no re-
  criticality state because there were no significant changes at the 
  monitoring post and as the result of the sampling for the Gas Control 
  System of the Unit 2; we confirmed that the concentration of Xe-135 was 
  below the detectible limit. Through the investigation, we confirmed the 
  concerned device is soundness. We submitted the report on the soundness 
  of concerned device and the alternative method for monitoring temperature 
  inside the Reactor of Unit 2 at Fukushima Daiichi Nuclear Power Station 
  to NISA on March 1. We continue the observation of the concerned device.
  · At 5:00 am on March 12, the temperature of the lower part of the RPV 
    (top of the lower head 135°) : approximately 42.0 °C 
  · At 5:00 am on March 12, the temperature of the lower part of the RPV 
    (top of the lower head 270°) : approximately 40.1 °C (Reference)
- 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 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. 1.8 m3/h and that from the core spray system is approx. 5.2m3/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. 
- As installation works of the PCV gas control system was completed, we 
  started a test operation at 11:38 am on February 23, 2012. We confirmed 
  that an exhaust flow amount was stable at 33Nm3/h at 2:10 pm and started 
  an adjustment operation.
- At 4:26 pm on November 30, 2011, 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, 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.
 
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.
 
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.
- At 8:47 am on March 11, we started transferring the 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]).
- At 10:10 am of March 10, 2012, we started transferring the accumulated 
  water from the basement floor of the turbine building of Unit 3 to the 
  centralized radiation waste treatment facility (Miscellaneous Solid Waste 
  Volume Reduction Treatment Building [High Temperature Incinerator 
  Building]).
- At 8:37 am on March 12, 2012, we started transferring the water 
  accumulated in the site banker building to the process main building in 
  the centralized waste treatment facilities. 
- At 10:00 am on March 12, 2012, we started transferring the water 
  accumulated in the basement of Unit 6 Turbine Building to temporary tanks.