* The 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, 2011. It was assumed to be hydrogen
explosion.
- At 3:37 pm on March 25, 2011, 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 10:11 am on December 10, 2011, in addition to water injection from
water feeding system, we started water injection from piping of core
spray system to the reactor.
The Current water injection volume is approx. 4.4 m3/h from the reactor
feed water system and approx. 2 m3/h from the core spray system.
- At 1:31 am on April 7, 2011, we commenced injection of nitrogen gas into
Primary Containment Vessel.
- At 11:22 am on August 10, 2011, 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, 2011, we completed installation of the cover for the
Reactor Building in order to contain dispersion of radioactive substances.
- At 4:04 pm on November 30, 2011, we started operation to inject nitrogen
into the reactor pressure vessel.
- At 6:00 pm on December 19, 2011, a full-scale operation of the PCV gas
management system started.
Unit 2 (Shut down)
- At approximately 6:00 am on March 15, 2011, an abnormal noise began
emanating from nearby Pressure Suppression Chamber and the pressure
within the chamber decreased.
- At 10:10 am on March 26, 2011, 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, 2011, in addition to water injection from
water feeding system, we started water injection from piping of core
spray system to the reactor.
- At 5:10 pm on January 25, regarding the reactor injection from the feed
water system at the Unit 2, we changed the injection line from the pump
located uphill to the T/B reactor injecting pump.
- At 9:47 am on January 26, due to the change of injection duct owned by
the pump located uphill, the volume from the feed water system increased
from approx. 7.9m3/h to 8.7 m3/h, and the volume from the reactor core
system decreased from approx. 1.0m3/h to 0m3/h.
The current water injection amount from the reactor feed water system is
approx. 8.7 m3/h and that from the core spray system is approx. 0 m3/h.
- At 5:21 pm on May 31, 2011, 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, 2011, we started injecting nitrogen gas into the
Primary Containment Vessel.
- At 6:00 pm on October 28, 2011, a full-scale operation of the PCV gas
management system started.
- At 10:46 am on December 1, 2011, we started the nitrogen injection to
the Reactor Pressure Vessel.
- At 11:50 am on January 19, 2012, we started the operation of the spent
fuel pool desalting facility.
- At 2:17 pm on January 24, 2012, at the desalting facility of the spent
fuel pool of Unit 2, an emergency alarm of "RO unit warning" activated,
and the system stopped automatically. We are currently checking for cause
of the alarm. All of the separation valves of the system were closed by
the inter-lock, and the alternative cooling system continues operation.
Therefore, there is no influence on cooling, In addition, as a result of
the on-site confirmation, no liquid leakage was confirmed. At 3:40 pm on
January 25, 2011, we found there are no abnormalities by resuming the
device. Since we could not detect the cause of the alarm warming although
we think it resulted from the filter clogging, we will continuously
monitor the progress.
Unit 3 (Shut down)
- Explosive sound and white smoke were confirmed at approximately 11:01 am
on March 14, 2011. It was assumed to be hydrogen explosion.
- At 6:02 pm on March 25, 2011, 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, 2011, we started water injection by core spray
system in addition to water injection by the reactor feed water system
piping arrangement.
The current water injection amount from the reactor feed water system is
approx. 8.1 m3/h and that from the core spray system is approx. 1 m3/h.
- At 7:47 pm on June 30, 2011, 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, 2011, injection of nitrogen gas into the Primary
Containment Vessel started.
- At 4:26 pm on November 30, 2011, we started operation to inject nitrogen
into the reactor pressure vessel.
- At 3:18 pm on January 14, we started operation of the radioactive
material removal instrument for the spent fuel pool in Unit 3
Unit 4 (Outage due to regular inspection)
- At around 6 am on March 15, 2011, 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, 2011, 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 (from 1:30 pm to 3:14 pm on January 12,
2012, we injected hydrazine [corrosion inhibitor] in conjunction with
the cyclic cooling).
- At 10:58 am on November 29, 2011, in order to decrease more salinity, we
installed Ion exchange equipment and started the operation of such
equipment.
- 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, 2011, we started the Residual Heat Removal System
Pump in order to cool the spent fuel pool.
- At 2:45 pm on July 15, 2011, we started the operation of the original
Residual Heat Removal System (System B) by its original seawater pump.
- At 10:11 am on December 22, 2011, since we finished the recovery work of
seawater pump (System B) of equipment water cooling system, we made a
trial run. At 11:25 am on the same day, we confirmed no abnormalities
and restarted the operation.
- 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, 2011, we started the Residual Heat Removal
System Pump of Unit 6 to cool down Spent Fuel Pool.
- At 2:33 pm on September 15, 2011, 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 moment, we do not think there is any reactor coolant leakage
inside PCV.
Others
- At around 10:00 am on June 13, 2011, 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, 2011, 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, 2011, 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, 2011, 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.
- On October 28, 2011, 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 12:25 pm on December 13, 2011, we started the re-circulating operation
of desalination facility (reverse osmosis membrane type) for the purpose
of suppression of condensed water after desalination treatment.
- As finding of accumulated water containing radioactive materials at the
trench between the Process Main Building and the Miscellaneous Solid
Waste Volume Reduction Treatment Building [High Temperature Incinerator
Building] (December 18, 2011), we started the inspection of other
trenches at the site on January 11.
- As a result of the inspection carried out on January 25, the nuclides
analyzed at the locations where the accumulated water was discovered are
as follows (advance report):
- Inside of the connecting duct of Unit 1 Waste Liquid Surge Tank
I-131: below measurable limit, Cs-134: approx. 1.2x101Bq/cm3, Cs-137:
approx. 1.5x101Bq/cm3
- Inside of the main transformer cable duct
I-131: below measurable limit, Cs-134 :approx. 1.5x100Bq/cm3, Cs-137 :
approx.2.3x100Bq/cm3
- Inside of the fire extinguishing duct trench
I-131: below measurable limit, Cs-134 : below measurable limit, Cs-137 :
approx.1.0x10-1Bq/cm3
- From 9 :42 pm on January 25 to 8:13 am on January 26, we transferred the
accumulated water from the basement of T/B, Unit 2 to the Centralized
Waste Treatment Facility (Miscellaneous Solid Waste Volume Reduction
Treatment Building [High Temperature Incinerator Building] and Process
Main Building).
- From 9 :53 pm on January 25 to 8:18 am on January 26, we transferred the
accumulated water from the basement of T/B, Unit 3 to the Centralized
Waste Treatment Facility (Miscellaneous Solid Waste Volume Reduction
Treatment Building [High Temperature Incinerator Building] and Process
Main Building).
- On October 27, when a contracted company was conducting the annual
checkup of a ceiling crane, which handles used fuel casks, a crack was
found on the casing of the connection point of the vehicle for driving.
After that, as we found that the damaged part was a crack that occurred
at the gear coupling cover of the vehicle's running drive, we completed
a replacement of the part with a same kind. On January 25, 2012, we
confirmed completion of the crane rehabilitation after we implemented a
loading test and made sure there are no abnormalities.