* 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.
Current water injection volume is approx. 4.6 m3/h from the reactor feed
water system and approx. 1.8 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 10:04 am on January 9, 2012, because the replacement work of the water
injection piping arrangement from the water feed system in association
with the trial run of reactor injection pump in Turbine Building has been
completed, we have adjusted the amount of injected water to the reactor
gradually. For the amount of injected water to the reactor, we adjusted
water injection from the reactor feed water system from approx. 1.7 m3/h
to 3.0 m3/h, and water injection from the core spray system for approx.
8.1 m3/h to 7.0 m3/h.
Current water injection volume is approx. 3.0 m3/h from the reactor feed
water system and approx. 7.0 m3/h from the core spray system.
- 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.
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.
Current water injection volume is approx 2.8 m3/h from the reactor feed
water system and approx. 6.1 m3/h from the core spray system.
- 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.
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.
- At around 1:00 pm on January 8, at circulating cooling system for spent
fuel pool of unit 4, we found water leakage from 4 points of cooling
pipe of air fin cooler (System B) when we tried to conduct scheduled
switching of air fin cooler (From System A to System B). Currently, we
are investigating the cause of the leakage. Leaked water is purified
water (pure water)* and is not contained radioactive materials. Now we
secluded the air fin cooler from the system to prevent the spread of
water leakage. In addition, the cooling of spent fuel pool has no problem
because we are currently using air fin cooler (System A) to cool spent
fuel pool.
* Purified water (pure water): The water from Sakashita dam
- 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.
Injured and others
- At 2:22 pm on January 9, 2012, at the Spent Sludge Storage Facility (*)
which is under construction, a partner company's worker who had been
engaged in concrete placement work reported his physical disorder. He was
carried to the emergency medical room of Unit 5/6 and received medical
treatment. Because he was in cardiopulmonary arrest, he was carried from
Fukushima Daiichi Nuclear Power Station to Iwaki Kyouritsu Hospital at
3:25 pm. No radioactive materials were found to be attached to the worker's
body.
* Spent Sludge Storage Facility: The facility to store radioactive waste
(spent sludge), which is produced during the process of accumulated
water treatment, on a temporary basis. Others
- At around 10 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 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.
- At approximately 10:40 am on January 9, 2012, a water pond was found near
the evaporative concentration apparatus 2B (under suspension) of the water
treatment facility. The amount of the water is about 11 liter and is
staying in the dam. The leakage was from float type flow meter at vent
condenser spray line of evaporative concentration apparatus(*) and the
amount of leakage is about one drop in 6 seconds. After closing the valve
of the line, it was about one drop in 15 - 20 seconds. A dish will be
settled under the leakage. The water is purified one in evaporative
concentration apparatus (for water injection to the reactor). We conduct
nuclide analysis for the water of the line regularly and the last result
was as fallows: β -ray is 6.0×10-1Bq/cm3 (November 29, 2011) and γ -ray
is below measurable limit (December 20, 2011).
*Vent condenser spray line of evaporative concentration apparatus:
cooling the vapor (purified water) that is generated in the evaporative
concentration apparatus and supply water for injection to the reactor.
