*New items 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. 3.9 m3/h through reactor feed
water system piping arrangement.
- We commenced injection of nitrogen gas into Primary Containment Vessel
at 1:31am on April 7.
- At 9:00 am on August 10, we started to assemble steel frame for the
Reactor Building Cover.
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.
Water is currently injected at approx. 3.9 m3/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. However at 4:22 pm on August 10, we adjusted the flow rate of injection water to the reactor. 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 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 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 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 Pump (B).
- At this time, 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 this time, we don't think there is any reactor coolant leakage inside
the primary containment vessel.
- From 9:30 am to 1:40 pm on August 9, we conducted plumbing between
temporary pump and residual heat removal system pump (A) to enforce the
connection method. We stopped the power source of residual heat removal
system pump (B) during this work. Even though cooling of a reactor and a
spent fuel pool were temporarily suspended, there are no safety issues
regarding this.
Operation for cooling the Spent Fuel Pools
- At 5:21 pm on May 31, we started cyclic cooling of Spent Fuel Pool of
Unit 2 by using alternative cooling system of the Pool's cooling and
filtering system.
- At 7:47 pm on June 30, we started cyclic cooling of Spent Fuel Pool of
Unit 3 by using alternative cooling system of the Pool's cooling and
filtering system.
- At 0:44 am on July 31, we started cyclic cooling of Spent Fuel Pool of
Unit 4 by using alternative cooling system of the Pool's cooling and
filtering system.
- At 11:22 am on Aug 10, we started cyclic cooling of Spent Fuel Pool of
Unit 1 by using alternative cooling system of the Pool's cooling and
filtering system.
Injured
- Around 12:05 pm on August 10, one partner company worker who was mowing
for curing of water treatment hose at west side of Centralized Radiation
Waste Treatment Facility (outside) was injured his right leg by sickle
and was transferred to the Fukushima Rosai Hospital by the ambulance.
Diagnose was given as contusion of right leg.
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 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 8:00 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 8:42 am on August 5, we started transferring accumulated water at
Unit 3 turbine building to Centralized Radiation Waste Treatment
Facility.
- At 10:00 am on August 9, we started transferring low level accumulated
water from outdoor temporary tanks to Mega Float. However, at 10:12 am,
since leakage was confirmed from the transferring pipes cabled at
outside, we stopped transferring. Thereafter, such pipes were replaced
and at 1:35 pm, we resumed transferring.
- At 11:00 am on August 9, we started transferring of accumulated water
from inside the Unit 6 turbine building to temporary tanks and finished on 5:00 pm on August 10.
- At 4:47 pm on August 10, we started transferring of accumulated water from turbine building of unit 2 to Centralized Radiation Waste Treatment Facility.
- At 10:00 am on August 11, we started transferring of accumulated water from inside the Unit 6 turbine building to temporary tanks.
