*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 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 Primary 
 Containment Vessel, we commenced the valve opening operation concerning 
 injection of nitrogen gas into the primary containment vessel at 10:30 pm 
 April 6 and commenced injection at 1:31am April 7.
-At 11:50 am on May 17, we have decreased the amount of freshwater 
 injected into the reactor from approximately 10 m3/h to approximately
 6 m3/h, since we have finished monitoring 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 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.
-At 5:39 am on May 20, we have decreased the amount of water injection 
 through fire protection system from approximately 9 m3/h to 
 approximately 8 m3/h, at 8:43pm further decreased from approximately 
 8 m3/h to approximately 7 m3/h, and at 11:54 from approximately 7 m3/h 
 to approximately 6 m3/h. 
-The current rate of water injection is approximately 6 m3/h through the
 fire protection system piping arrangement and approximately 12 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 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 cold shutdown.
-At this moment, we do not consider any reactor coolant leakage inside the 
 primary containment vessel 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 cold shutdown.
-At this moment, we do not consider any reactor coolant leakage inside the 
 primary containment vessel happened. 

Operation for cooling the spent fuel pools 
-At 3:06 pm on May 20, we started water spray to Unit 1 by a concrete 
 pumping vehicle, however, since there was a possibility that the water 
 was not properly poured into the spent fuel pool due to the wind and 
 other factors, we stopped spray at 4:15pm. 
-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.
-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 water from 
 the underground level of reactor building to the radiation waste treatment
 facility of Unit 6.
-At 6:04 pm on May 17, we started transfer of high level radioactive waste 
 water from the underground level of the turbine building of Unit 3 to the 
 Centralized Radiation Waste Treatment Facility.
-On May 20, we have conducted improvement of monitoring environment to 
 some of the 8 detectors (No. 8) set at the boundaries of the power station
 by implementing decontamination and putting shield to the lower part of 
 the detector.
-At 9:35 am on May 21, Mega Float which is planned to be used for storing 
 low level radioactive waste liquid arrived at the shallow draft quay. 
-We will continue to take all measures to ensure the safety and to 
 continue monitoring the surrounding environment around the power station.