*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 at
3:36 pm on March 12. It was assumed to be a hydrogen explosion.
- At approximately 2:30 am on March 23, seawater injection to the nuclear
reactor through the feed water system was initiated.
- From 3:37pm on March 25, we started injecting freshwater and are now
injecting fresh water utilizing a motor-driven pump powered by the
off-site transmission line. From April 27, we increased the amount of
freshwater being injected from approximately 6 m3/h to approximately 14
m3/h. At 10:14am on April 29, we cut the amount of injecting freshwater
back to approximately 6 m3/h.
- Since it is suspected that hydrogen gas has accumulated inside reactor
containment vessel, we commenced the valve opening operation which is
the 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 the nearby Pressure Suppression Chamber and the pressure within the
chamber decreased.
- From 10:10 am on March 26, we started injecting freshwater into the
reactor and are now injecting fresh water via 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 using a motor-driven pump
powered by the off-site transmission line.
Unit 4 (Outage due to regular inspection)
- At approximately 6:00am on March 15, we confirmed that there had been an
explosion resulting in sustained damage around the 5th floor rooftop
area of the Nuclear Reactor Building.
- At the moment, we believe that there hasn't been any reactor coolant
leakage inside the reactor.
Unit 5 (Outage due to regular inspection)
- Sufficient level of reactor coolant to ensure safety is maintained.
- At 5:00am on March 19, we started the Residual Heat Removal System Pump
(C) in order to cool the spent fuel pool.
- At 2:30pm on March 20, the reactor achieved a reactor cold shutdown.
- At the moment, we believe that there hasn't been any reactor coolant
leakage inside the reactor.
Unit 6 (Outage due to regular inspection)
- Sufficient level of reactor coolant to ensure safety is being maintained.
- At 10:14pm on March 19, we started the Residual Heat Removal System Pump
(B) of Unit 6 in order to cool the spent fuel pool.
- At 7:27pm on March 20, the reactor achieved a reactor cold shutdown.
- At the moment, we believe that there hasn't been any reactor coolant
leakage inside the reactor.
Operation for cooling the spent fuel pools
- From 12:19pm to 8:46pm on May 5, we conducted water spraying for Unit 4,
using the concrete pumping vehicle.
- At 9:36 am on May 6, we started water spraying for unit 2 using a
temporary electric pump.
- We will continuously conduct further water spraying depending on the
conditions of the 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 the Unit 6 turbine building to a
temporary tank was conducted from 2:00pm to 5:00pm on May 3.
- From March 27th, the transfer of accumulated water in the Unit 5 turbine
building to a condenser has been conducted, and water in the amount of
approximately 600m3 was transferred from March 27 to May 2.
- From May 2, we have started work relating to the set up of exhausters,
in order to improve the working environment inside the reactor building
of Unit 1. At 4:36pm on May 5th, all the exhausters (6 units) began
operating.
- We will continue to take all measures to ensure safety and will continue
monitoring the power station's surrounding environment.