*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 approximately 2:30 am on March 23, seawater injection to the nuclear 
  reactor through the feed water system was initiated.
- From 3:37 pm on March 25, we started injecting freshwater and are now 
  injecting fresh water by a motor driven pump powered by the off-site 
  transmission line.
- As it is suspected that hydrogen gas is accumulated inside reactor 
  containment vessel, we commenced the valve opening operation concerning 
  injection of nitrogen gas into the reactor container vessel at 10:30 pm 
  April 6th and commenced injection at 1:31am April 7.
- At 1:28 pm on May 15, we have increased the amount of freshwater injected 
  into the reactor from approximately 8 m3/h to approximately 10 m3/h so 
  that we can monitor the trend shift of parameters of the Reactor Pressure 
  Vessel as well as the Primary Containment Vessel, the shift which would 
  be resulted from the increase of the amount of injected freshwater. 

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. 
- From 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. 

Unit 3 (Shut down) 
- Explosive sound and white smoke were confirmed at approximately 11:01am 
  on March 14. It was assumed to be hydrogen explosion.
- From 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 4:53 pm on May 12, as a part of work to switch the water injection 
  line to the nuclear reactor from the fire extinction system to the 
  reactor feed water system, we started water injection through the reactor 
  feed water system in addition to through the fire extinction system. 
  The current rate of water injection is approximately 9 m3/h through the 
  fire extinction system piping arrangement and approximately 6 m3/h 
  through the reactor feed water system piping arrangement (We made a 
  mistake on the rate of water injection in the report as of 10 am, May 15 
  and have corrected it).
- From 2:33 pm to 5:00 pm on May 15, we injected boric acid to the reactor 
  through the fire extinction system. 

Unit 4 (Outage due to regular inspection) 
- At approximately 6:00 am on March 15, we confirmed the explosive sound 
  and the sustained damage around the 5th floor rooftop area of the Nuclear 
  Reactor Building.
- At this moment, we do not consider any reactor coolant leakage inside the 
  reactor happened. 

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 
  (C) in order to cool the spent fuel pool.
- At 2:30 pm on March 20, the reactor achieved reactor cold shutdown. 
- At this moment, we do not consider any reactor coolant leakage inside 
  the reactor happened. 

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 
  (B) of Unit 6 in order to cool the spent fuel pool.
- At 7:27 pm on March 20, the reactor achieved reactor cold shutdown. 
- At this moment, we do not consider any reactor coolant leakage inside the 
  reactor happened. 

Operation for cooling the spent fuel pools 
- From 4:25 pm to 8:25 pm, on May 15, we sprayed water into the spent fuel 
  pool of Unit 4 by a concrete pumping vehicle (from 4:26 pm to 8:30 pm, 
  injected hydrazine [corrosion inhibitor] at the same time). 
- From 3:00 pm on May 16th, we began spraying water to Unit 3 by a 
  temporary motor driven pump. 
- We will continuously conduct further water spray depending on the 
  conditions of spent fuel pools, if needed. 

Others 
- At 1:30 pm on April 26, we started spraying the dust inhibitor inside 
  the building.
- At 10:08 am on April 19, we started transfer of high level radioactive 
  wastewater from the vertical shaft near the turbine building of Unit 2 
  to the Centralized Radiation Waste Treatment Facility.
- At 2:00 pm on May 1, we started transferring the accumulated water in 
  turbine building of Unit 6 to temporary tanks.
- At 11:00 am on May 10, we started transferring the accumulated groundwater 
  inside the reactor building to the radiation waste treatment facility in 
  Unit 6.
- We will continue to take all measures to ensure the safety and to 
  continue monitoring the surrounding environment around the power station.