*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 3:37 pm on March 25, 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.
At 3:05 pm on October 30, we adjusted the amount of water injected to the
reactor approx.6.5 m3/h in order to improve the working condition inside
the covers by mitigating the evaporation from the reactor building.
The current water injection volume is approx 6.5 m3/h from the reactor
feed water system.
-We commenced injection of nitrogen gas into Primary Containment Vessel at
1:31 am on April 7.
-At 11:22 am on August 10, we started cyclic cooling for the water in the
spent fuel pool by an alternative cooling equipment of the Fuel Pool
Cooling and Filtering System.
-On October 28, we completed installation of the cover for the Reactor
Building in order to contain dispersion of radioactive substances.
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.
-At 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.
-At 2:59 pm on September 14, we started injecting water to the reactor
through core spray system water injection piping arrangement in addition
to the water injection through reactor feed water system piping
arrangement.
Water is currently injected at approx. 2.8 m3/h through reactor feed water
system piping arrangement, and at approx. 7 m3/h through core spray system
water injection piping arrangement.
-At 5:21 pm on May 31, we started cyclic cooling for the water in the spent
fuel pool by an alternative cooling equipment of the Fuel Pool Cooling and
Filtering System.
-At 8:06 pm on June 28, we started injecting nitrogen gas into the Primary
Containment Vessel.
-At 10:30 am on October 27, we conducted leak test of the system as a part
of construction to settle the gas control system of Primary Containment
Vessel at the reactor building of Unit 2. As a result, we confirmed in-
leak volume to the system had no problem. In addition, we conducted
tentative operation test. As a result, we confirmed operational aspect of
electric heater and exhaust fun had no problem.
At 12:53 pm on October 28, we activated the exhaust fan of the gas
management system of the reactor containment vessel in the reactor
building and started test operation. As we confirmed stable operation of
the system, from 6:00 pm on the same day, we put the system in operation.
Regarding the hydrogen concentration of the gas management system of the
reactor containment vessel in Unit 2, we confirmed that it increased to
approx. 2.3vol% at 5:00pm on 29 October, which was approx. 1vol% at the
beginning of the operation. Therefore we adjusted the amount of injecting
nitrogen gas from approx.14 Nm3/h to 16.5 Nm3/h in order to avoid
exceeding the combustible threshold concentration (4vol%) of hydrogen.
Unit 3 (Shut down)
-Explosive sound and white smoke were confirmed at approximately 11:01 am
on March 14. It was assumed to be hydrogen explosion.
-At 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 2:58 pm on September 1, we started water injection by core spray system
in addition to water injection by the reactor feed water system piping
arrangement.
Water is currently injected at approx. 2.6 m3/h through reactor feed water
system piping arrangement, and at approx. 8.1 m3/h through core spray
system water injection piping arrangement.
-At 7:47 pm on June 30, we started cyclic cooling for the water in the
spent fuel pool by an alternative cooling equipment of the Fuel Pool
Cooling and Filtering System.
-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 around 6 am on March 15, we confirmed the explosive sound and the
sustained damage around the 5th floor rooftop area of Reactor Building.
-At 12:44 pm on July 31, we started cyclic cooling for the water in the
spent fuel pool by an alternative cooling equipment of the Fuel Pool
Cooling and Filtering System.
-At 11:34 am on August 20, we started an operation of desalination
equipment in the spent fuel pool.
-At this moment, we don't think there is any reactor coolant leakage
inside the primary containment vessel.
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
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 (System B) by its original seawater pump.
-At this moment, we don't think there is any reactor coolant leakage
inside the primary containment vessel.
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
of Unit 6 to cool down Spent Fuel Pool.
-At 7:27 pm on March 20, the reactor achieved cold shutdown.
-At 2:33 pm on September 15, we started separately cooling the reactor
through the Residual Heat Removal System and the spent fuel pool through
Equipment Cooling Water System and Fuel Pool Cooling System.
-At this time, we don't think there is any reactor coolant leakage inside
the primary containment vessel.
Injuries
-At 8:30 am on October 29, two workers from the cooperating companies were
injured during dismantling of the large crane used to install the cover
for the Reactor Building, Unit 1 within the site boundary. At 9:50 am, one
worker departed the emergency room, Units 5 and 6 and will be transported
to a hospital by an air ambulance. The other worker will be transported to
the hospital by a company vehicle. At 10:35 am on October 29, we
transported one worker to Fukushima Medical University Hospital by an air
ambulance and provided medical treatment including operation. At 2:20 pm
on the same date, we transported the other worker to Sogo Iwaki Kyoritsu
Hospital, Iwaki City and provided medical checkup.
Others
-At around 10 am on June 13, we started the operation of the circulating
seawater purification facility installed at the screen area of Unit 2 and
3.
-At 8 pm on June 17, we started operation of Water Treatment Facility
against the accumulated water. 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 7:41 pm on August 19, we started treatment of accumulated water by
parallel operation of one line from the cesium adsorption instrument to
the decontamination instrument and the other treatment line of the cesium
adsorption instrument No.2.
-At 2:06 pm on October 7, we started to spray purified accumulated water
brought from Unit 5 and 6 continually in order to prevent dust scattering
and potential fire outbreaks from the cut down trees.
-At 10:12 am on October 20, we started transferring the accumulated water
from the basement of turbine building of Unit 2 to the Process Main
Building of Central Radioactive Waste Treatment Facility. At 9:32 am on
October 28, we stopped transferring the accumulated water from the
basement of turbine building of Unit 2 to the Process Main Building of
Central Radioactive Waste Treatment Facility temporarily, and after
checking the systematic diagram, at 9:54 am on October 28 we changed the
destination of transferring the accumulated water to High Temperature
Incinerator Building of Centralized Radiation Waste Treatment Facility.
-On October 28, we started installation of the water proof wall at the sea
side, in front of the existing shore protection, Units 1-4, in order to
contain marine pollution by underground water.
-At 10:00 am on October 30, we started transferring accumulated water from
the turbine building of Unit 6 to the temporarily build tank.
