* 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. To improve reliability of water injection
to a reactor, line connecting to injection piping in water injection
line of reactor injection pump on the hill of Unit 1 had replaced with
polyethylene piping. So at 10:35 am, we changed injection route from
injection pump in turbine building to reactor injection pump on the hill.
We confirmed the decrease in volume of injecting water to reactors, so
at 3:15 pm on February 2, we adjusted volume of water injection in each
reactor as follows: Feed water system from approx. 4.2 m3/h to approx.
4.5 m3/h, Reactor core spray system from approx. 1.5 m3/h to approx. 2.0
m3/h.
The current water injection amount from the reactor feed water system is
approx. 4.5m3/h and that from the core spray system is approx. 2.0m3/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.
- 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. To improve reliability of water injection
to a reactor, line connecting to injection piping in water injection
line of reactor injection pump on the hill had replaced with
polyethylene piping.. At 10:55 am in February 2, we adjusted water
injection volume to the reactor of Unit 2 through the feed water system
from approx. 3.9 m3/h to approx. 3.0 m3/h, and the volume from the
reactor core spray system from approx. 5.1 m3/h to approx. 6.0m3/h. We
confirmed the decrease in volume of injecting water to reactors, so at
3:15 pm on February 2, we adjusted volume of water injection in each
reactor as follows: Feed water system from approx. 2.5 m3/h to approx.
3.0 m3/h, Reactor core spray system from approx. 5.2 m3/h to approx. 5.5
m3/h.
The current water injection amount from the reactor feed water system is
approx. 3.0m3/h and that from the core spray system is approx. 5.5m3/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. On February 1 2012, we conducted sampling of
the gas of the PCV gas management system. As a result of the analysis,
we confirmed that at the entrance of the system Xenon 135 was below
detection limit (9.5x10-2Bq/cm3), and below the re-criticality
criterion which is 1Bq/cc.
- 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. To improve reliability of water injection to
a reactor, line connecting to injection piping in water injection line
of reactor injection pump on the hill had replaced with polyethylene
piping. At 11:10 am on February 2 , we adjusted water injection volume
to the reactor of Unit 3 through the feed water system from approx. 3.8
m3/h to approx. 3.0 m3/h, and the volume from the reactor core spray
system from approx. 5.2 m3/h to approx. 6.0m3/h. We confirmed the
decrease in volume of injecting water to reactors, so at 3:15 on
February 2, we adjusted volume of water injection in each reactor as
follows: Feed water system from approx. 2.5 m3/h to approx. 3.0 m3/h,
Reactor core spray system from approx. 5.2 m3/h to approx. 5.5m3/h.
The current water injection amount from the reactor feed water system is
approx. 3m3/h and that from the core spray system is approx. 5.5m3/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.
- 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 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. 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). We
estimated the amount of water leaked is 8,500 litters by measuring
decrease in water level of skimmer surge tank
- At 3:20 pm on February 2 , a Tepco worker on patrolling at reactor
building of Unit 4 found the very small flow(just as much as lead in
pencil) of water in north west corner in first floor of the reactor
building. This leakage seemed to be occurred at make up water system in
reactor well because the valve at reactor well is closed totally and so
the leakage seemed not be from reactor well. We are investigating
further. No water leakage to out side 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 5:00 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 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.
- From 10:00 am to 4:00 pm on February 1, we conducted transferring the
accumulated water from Unit 6 Turbine Building to temporary tanks. From
10:00 am to 4:00 pm on February 2, we transferred the accumulated water
from Unit 6 Turbine Building to temporary tanks.
- At 8:36 am on February 2, second Cesium adsorption apparatus was stopped
to backwash the filter because there was a gradual downward tendency. At
11:12 am of the same day, we restarted the apparatus and at 11:15 am,
reached to steady volume of water flow (36m3/h)
- Newly found water leakage caused by congelation after the latest report
(at 10:00 am February 1) are as follows:
· two valves in discharged water piping at water treatment building
where filtrate water purified(Found at 3:30 pm on February 2 )
· (Filtrate water(water taken from dam): approx. 0.5 litters)
