*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. It was assumed to be hydrogen explosion.
- At 3:37 pm on March 25, 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.
- We commenced injection of nitrogen gas into Primary Containment Vessel
at 1:31 am on April 7.
- At 11:22 am on August 10, 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.
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.
- At 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.
- At 2:59 pm on September 14, we started injecting water to the reactor
through core spray system water injection piping arrangement in addition
to the water injection through reactor feed water system piping
arrangement. Water is currently injected at approx. 2.9m3/h through
reactor feed water system piping arrangement, and at approx. 7.1 m3/h
through core spray system water injection piping arrangement.
- At 5:21 pm on May 31, 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, we started injecting nitrogen gas into the
Primary Containment Vessel.
- At 10:30 am on October 27, we conducted leak test of the system as a
part of construction to settle the gas control system of Primary
Containment Vessel at the reactor building of Unit 2. As a result, we
confirmed in-leak volume to the system had no problem. In addition, we
conducted tentative operation test. As a result, we confirmed
operational aspect of electric heater and exhaust fun had no problem.
At 12:53 pm on October 28, we activated the exhaust fan of the gas
management system of the reactor containment vessel in the reactor
building and started test operation.
Unit 3 (Shut down)
- Explosive sound and white smoke were confirmed at approximately 11:01 am
on March 14. It was assumed to be hydrogen explosion.
- At 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.
- At 2:58 pm on September 1, we started water injection by core spray
system in addition to water injection by the reactor feed water system
piping arrangement.
water system piping arrangement, and at approx. 8.0 m3/h through core
spray system water injection piping arrangement.
- At 7:47 pm on June 30, 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, injection of nitrogen gas into the Primary
Containment Vessel started.
Unit 4 (Outage due to regular inspection)
- At around 6 am on March 15, 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, 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 11:34 am on August 20, we started an operation of desalination
equipment in the spent fuel pool.
- 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, 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 (System B) by its original seawater pump.
- 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 2:33 pm on September 15, 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 time, we don't think there is any reactor coolant leakage inside
the primary containment vessel.
Others
- 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 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 7:41 pm on August 19, 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, 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.
- We transferred the accumulated water from the basement of turbine
building of Unit 3 to the High Temperature Incinerator Building of
Central Radioactive Waste Treatment Facility from 10:00 am on October 20
to 9:16 am on October 28.
- At 10:12 am on October 20, we started transferring the accumulated water
from the basement of turbine building of Unit 2 to the Process Main
Building of Central Radioactive Waste Treatment Facility. At 9:32 am on
October 28, we stopped transferring the accumulated water from the
basement of turbine building of Unit 2 to the Process Main Building of
Central Radioactive Waste Treatment Facility temporarily, and after
checking the systematic diagram, at 9:54 am on October 28 we changed the
destination of transferring the accumulated water to High Temperature
Incinerator Building of Centralized Radiation Waste Treatment Facility.
- Partner companies' worker found the crack at connection casing in
driving shaft of ceiling crane, which is used to deal with spent fuel
casks and located in the common spent fuel pool building, during its
annual check out. We will check carefully the situation of the
connection casing in greater detail.
- At 9:30 am on October 28, we changed lines of injecting water to reactor
of Unit 1 and Unit 2 from regular line to emergency line for the purpose
of adding flow controlling valve to the water injection line of Unit 1
which would upgrade the control ability of water flow.
At 1:30 pm, after the completion of the above work, we changed lines of
injecting water to reactor of Unit 1 and Unit 2 from emergency line to
regular line. At the same time, the amount of water from the reactor
feed water system was adjusted to approx. 3.9 m3/h at Unit1. At Unit 2,
the amount of injected water was adjusted to approx. 3m3/h from the
reactor feed water system and approx. 7m3/h from the core spray system.
(The stability of the flow rate was confirmed at 2:00 pm).
- We stopped the water desalination facilities after detecting a water
leakage (approx. 20L) from the pump and stopped the facilities. After we
confirmed that the leakage stopped, at 2:30 pm on the same day, we
stopped the line connecting to the water pump and started other water
desalinations. At 4:20 pm, the rated flow reached 50 m3/h. From October
27 to 28, we exchanged the pump.
- At 2:20 pm on October 28, one of the TEPCO staff felt sick and threw up
while he was checking the documents in the administration office
building, because the full-covered mask was tied too tightly. Because he
put off the mask temporarily when he threw up, he will be tested with
the whole body counter just in case. No radioactive materials was
detected on his face.
