*Updates from previous press release 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 which is now powered by the off-site transmission line.
Water is currently injected at approx. 4.0m3/h through reactor feed
water system piping arrangement.
- We commenced injection of nitrogen gas into Primary Containment Vessel
at 1:31am on 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. From 2:25pm on July 17, the motor
driven pump of Unit 2 is injecting the freshwater to the Unit 1 and 2
reactors.
Water is currently injected at approx. 4.1m3/h through reactor feed
water system piping arrangement.
- At 8:06 pm on June 28, we started injecting nitrogen gas into the
Primary Containment Vessel.
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.
Water is currently injected at approx. 9.1 m3/h through reactor feed
water system piping arrangement.
- At 8:01 pm on July 14, injection of nitrogen gas into the Primary
Containment Vessel started.
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 2:45pm on July 15, we started the operation of the original Residual
Heat Removal System Pump (B).
- 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.
- At 7:47 pm on June 30, we started cyclic cooling of the spent fuel pool
in Unit 3 using alternative cooling system for fuel pool cooling and
filtering system.
- We will continuously conduct further water spray depending on the
conditions of spent fuel pools, if needed.
Injury accident
- Around 10:06am on July 18, a worker of the partner company fell from the
distribution pole during the connection work of the optical cable near
the observatory entrance* of the station. He was transported to the
Iwaki Kyouritsu Hospital by the helicopter emergency medical service
(called "Doctor Heli").
*: Modification on the place where the accident happened
Others
- 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 approximately 10:00 am on June 13, we started the operation of the
circulating seawater purification facility installed at the screen area
of Unit 2 and 3.
- From 8:00 pm on June17, we started operation of water treatment of
accumulated water at accumulated water treatment facility.
- At 6:00 pm on July 2, we started the circulating injection cooling to
inject the water, which was treated by the accumulated water treatment
system, to the reactors through the buffer tank.
- At 10:50 am on July 16, we started transfer of the accumulated water
from the Turbine Building of Unit 3 to the Process Main Building of the
Centralized Radiation Waste Treatment Facility.
- At 10:56 am on July 16, we started transfer of the accumulated water
from the Turbine Building of Unit 2 to the Process Main Building of the
Centralized Radiation Waste Treatment Facility.
- From 8:30am on July 18, we started an installation work of a temporary
roof for the Unit 3 turbine building in order to cover the roof's
opening as a measure for rainwater.
- At 11:00 am on July 19, we stopped the operation of the cesium
adsorption system at accumulated water treatment facility in order to
replace the cesium adsorption towers.
- We will continue to take all measures to ensure the safety and to
continue monitoring the surrounding environment around the power station.