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Press Release (May 22,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 3:00 pm, May 22)
 
*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. We are now
 injecting freshwater by a motor driven pump powered by the off-site
 transmission line at 6 m3/h.
-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.
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 at 7 m3/h.
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. 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.
-From 4:00 pm to 7:56 pm on May 21st, we sprayed water to Unit 4 by a
 concrete pumping vehicle (from 4:23 pm to 7:00 pm, hydrazine was also
 injected)
-From 1:02 pm to 2:40 pm, on May 22nd, we injected water to Unit 2 by a 
 temporary motor-driven pump (from 1:04 pm to 2:03 pm, hydrazine was also 
 injected) 
-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.
-We will continue to take all measures to ensure the safety and to
 continue monitoring the surrounding environment around the power station. 
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