*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 reactor 
  through the reactor feed water system was initiated. 
- From 3:37 pm on March 25, we started injecting freshwater by a motor 
  driven pump powered by the off-site transmission line. We are now 
  injecting freshwater by a motor driven pump powered by the off-site 
  transmission line. 
  The current rate of water injection is approx. 5 m3/h through reactor 
  feed water system piping arrangement. 
- As it was suspected that hydrogen gas had been accumulated inside Primary 
  Containment Vessel, we commenced the valve opening operation concerning 
  injection of nitrogen gas into the primary containment vessel at 10:30 pm 
  on April 6 and commenced injection at 1:31am April 7. 
 
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 freshwater by a motor driven pump powered by the 
  off-site transmission line. 
  The current rate of water injection is approx. 5 m3/h through the reactor 
  feed water system piping arrangement. 
 
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. 
  The current rate of water injection is approx. 11.5 m3/h through the 
  reactor feed water system piping arrangement. 
 
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 Reactor 
  Building. 
- At this moment, we do not consider any reactor coolant leakage inside the 
  primary containment vessel has occurred. 
 
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 cold shutdown. 
- At this moment, we do not consider any reactor coolant leakage inside the 
  primary containment vessel has occurred. 
 
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 cold shutdown. 
- At this moment, we do not consider any reactor coolant leakage inside the 
  primary containment vessel has occurred. 
 
Operation for cooling the spent fuel pools 
- At 5:21 pm on May 31, we started cyclic cooling of the spent fuel pool in 
  Unit 2 using alternative cooling system for fuel pool cooling and 
  filtering system. 
- From 2:23 pm to 7:45 pm on June 4, we started water spray to Unit 4 by a 
  concrete pumping vehicle (from 2:51pm, also injected hydrazine [corrosion 
  inhibitor] at the same time).  
- 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 
  site. 
  On May 27, we started spraying dust inhibitor to Turbine Building of 
  Units 1. We will implement spraying the dust inhibitor to other turbine 
  and reactor buildings of Units 1 to 4. 
- At 2:00 pm on May 1, we started transferring accumulated water in the 
  turbine building of Unit 6 to temporary tanks. 
- At 11:00 am on May 10, we started transferring accumulated water from the 
  underground level of reactor building to the radiation waste treatment 
  facility of Unit 6. 
- At 8:00 am on May 31, 2011, we confirmed oil leakage to the sea around 
  the curtain wall of the water intake canal of Unit 5 and 6, Fukushima 
  Daiichi Nuclear Power Station. As a result of our investigation, we 
  confirmed that oil leaked from pipes around seawall to the port through 
  holes of steel sheet piles and that the leakage has already stopped. 
  Since the diffused area was just around the curtain wall and the surface 
  of the sea around Shallow Draft Quay and the oil film was very thin, we 
  confirmed that there is no spread to the outer sea. We completed 
  installing oil-absorbing mat around seawall at approximately 2:00 pm and 
  also installed oil fences at 4:50 pm. We plan to protect pipes around s 
  eawall and collect the oil. 
- From 12:50 pm on June 2 to 9:56 pm on June 4, we transferred accumulated 
  water from the condenser of turbine building of Unit 3 to the condensate 
  storage tank of Unit 3. 
- At 6:39 pm on June 4, we started transferring accumulated water from 
  vertical shafts (trenches) of turbine building of Unit 2 to Process Main 
  Building. 
- We will continue to take all measures to ensure the safety and to 
  continue monitoring the surrounding environment around the power station.