*New 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. From on April 27, we have increased the amount of
injecting freshwater from approximately 6 m3/h to approximately 14 m3/h.
At 10:14 am on April 29, we put the amount of injecting freshwater back
to approximately 6 m3/h.
- 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.
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.
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 10:05 am to 11:40 am, May 2, water injection to Unit 2 was
conducted by temporary motor driven pump.
- We will continuously conduct further water spray depending on the
conditions of spent fuel pools, if needed.
Others
- Regarding the transfer of high level radioactive wastewater in Unit 2 to
the Centralized Radiation Waste Treatment Facility, while we temporarily
suspended transfer due to the inspection of transferring facilities at
9:16 am on April 29, transfer was restarted at 2:05pm on April 30.
- The transfer of accumulated water in Unit 6 turbine building to a
temporary tank was conducted from 2:00 pm to 5:00 pm on May 1 and the
transfer was restarted from 10:00 am, May 2.
- 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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