*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 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. 3.7m3/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. 3.4m3/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.
-At 8:43 am on July 22, since the volume of injected water into the
reactor was found to be decreased, we adjusted the volume up to 3.8m3/h.
Hence, water is currently injected at approx. 3.8m3/h through reactor
feed water system piping arrangement.
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. 9.0m3/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 2:45 pm 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 10:06 am 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"). According to the result of physical examination, he was
diagnosed as "fracture of distal end of right radius, of left radius head,
and left ligamentum collaterale ulnae."
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 June 17, 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.
-From 10:50 am on July 16 to 3:59 pm on July 21, we transferred of the
accumulated water from the Turbine Building of Unit 3 to the Process Main
Building of the Centralized Radiation Waste Treatment Facility.
-From 10:56 am on July 16 to 4:04 pm on July 21, we transferred of the
accumulated water from the Turbine Building of Unit 2 to the Process Main
Building of the Centralized Radiation Waste Treatment Facility.
-From 8:30 am 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.
-On July 21, in order to conduct a restoration work for double circuit of
Yonomori line which is power source for Unit 5 and Unit 6, we started a
power switching work to stop the operation of Okuma Line No.3 which was
connected to Yonomori Line No.1. According to this work, we stopped the
alternative cooling system for the fuel pool cooling and filtering system
of Unit 3 at 8:02 am, the water treatment system at 8:38 am, and the
cooling system for the common pool at 8:40 am. After that, upon starting
of power receiving from Okuma Line No.2, we started the cooling system
for the common pool at 2:41 pm, and the alternative cooling system for
the fuel pool cooling and filtering system of Unit 3 at 2:52 pm. At 12:28
am on July 22, we started the operation of the water treatment facility,
resuming water processing at 12:40 am on the same day.
-At 7:10 am on July 22, the circuit breaker for the bus from Okuma line 2L
which supplies electricity to a part of power network in the power
station opened the circuit due to overload, resulting in the power off of
the following facilities: the alternative cooling facility for spent fuel
pool at Unit 3, water treatment facilities, the cooling facility of
common pool, monitoring gauges in the reactor of Unit 3 & 4, and Main
Anti-Earthquake Building. The following facilities which receive power
from other system had no affect: water injection and nitrogen gas
injection to reactor of each unit, each monitoring post, the alternative
cooling facility for spent fuel pool at Unit 2, monitoring gauges in the
reactor of Unit 1 & 2, all facilities of unit 5 & 6. Currently
investigations of the cause of the event as well as power restoration
work are underway. After that, we found no abnormalities at the secondary
side that have been tripped, we began receiving electricity from a power
network line called TEPCO Genshiryoku Sen to complete the restoration
works described below:
-At 09:33 am Power source of Main Anti-Earthquake Building
-At 10:35 am Monitoring instruments in Reactor of Unit 3 and 4
-At 10:40 am Cooling System of Common Pool
-At 11:50 am Substitute Cooling Facilities at Spent Fuel Pool Cooling
and Filtering System of Unit 3
-Water Treatment Facility is being prepared to restart operations.
-We will continue to take all measures to ensure the safety and to
continue monitoring the surrounding environment around the power station.
