* 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 amount from the reactor feed water system is
approx. 4.4m3/h and that from the core spray system is approx. 2m3/h.
- 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.
At 3:05 pm on January 30, we stopped the operation of the secondary
air-fin coolers of spent fuel pool in order to prevent overcooling of
alternative cooling system of spent fuel pool of Unit 1. (the temperature
of fuel pool at the time of stoppage: 12°C)
- 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.
After we finished replacing the water injection line from the reactor
water injection pump on the hill to polyethylene pipe in order to improve
the reliability of water injection to the reactor, we have been changing
the water injection volume to the reactor gradually. At 11:50 pm on
February 1, we adjusted the water injection volume to the reactor through
the feed water system from approx. 5 m3/h to approx. 4 m3/h, and the
volume from the reactor core spray system from approx. 4 m3/h to approx.
5m3/h.
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.
The current water injection amount from the reactor feed water system is
approx. 4m3/h and that from the core spray system is approx. 5m3/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.
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.
At 3:01 pm on January 27, the water injection to the reactor from the
feed water injection system was switched from the reactor water injection
pump in the turbine building to the reactor water injection pump on the
hill.
After we finished replacing the water injection line from the reactor
water injection pump on the hill to polyethylene pipe in order to improve
the reliability of water injection to the reactor, we have been changing
the water injection volume to the reactor gradually. At 11:50 pm on
February 1, we adjusted the water injection volume to the reactor through
the feed water system from approx. 5 m3/h to approx. 4 m3/h, and the
volume from the reactor core spray system from approx. 4 m3/h to approx.
5m3/h.
The current water injection amount from the reactor feed water system is
approx. 4m3/h and that from the core spray system is approx. 5m3/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.
Regarding the water leakage from Filtrate water supply valve of Unit 3
spent fuel pool cooling system occurred on January 29, we removed the
valve and completed installation of blanking plate. In addition, we are
suspending the secondary cooling tower in order to prevent overcooling of
spent fuel pool alternative cooling facility.
- 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.
- 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.
- At 4:05 pm on January 30, we started to transfer 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)
through newly installed polyethylene pipes.
- At 4:12 pm on January 30, we started to transfer 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)
through newly installed polyethylene pipes.
- At 10:00 am on February 1, we started transfer of the accumulated water
from Unit 6 Turbine Building to temporary tanks.
- At 9:18 am on January 31, we started transfer of Sub-drain Water of Unit
6 to the temporary tank. We will conduct transferring to the temporary
tank appropriately.
- At approx. 10:30 pm on January 31, we found that the water was leaking
from the indicator test line in the rack instruments for jet pumps were
stored on the first floor in Unit 4 Reactor Building. At 10:43 pm, the
leakage was stopped after the main valve leading to the rack was closed.
Debris were scattered around on the floor, and the volume of leaked water
was approx. 6 litters as far as we could confirmed. Please note that it
didn't run off outside of the reactor building. We sampled the water in
the test line and measured the radioactivity concentration. From the
results, we estimated the water leaked from the reactor well (analysis
result: 35.5 Bq/cm3).
- Newly found water leakage after the previous announcement (as of 3:00 pm
January 31) is as follows;
· Casing of the water injection pump (electrically driven pump for Unit
2) at the side of the pure water tank (found approx. at 4:00 pm on
January 31)
(Filtrate water*: approx. 10 L)
* Filtrate water: water taken from the dam
· Indicator (flow rate transmitter) test line in the instrument rack
(instrument rack for the jet pump) at the southwest corner on the first
floor of Unit 4 Reactor Building (found approx. at 10:30 pm on January
31) (Water from the reactor well: approx. 6 L)
