*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 12th. It was assumed to be hydrogen
explosion.
-At approximately 2:30 am on March 23rd, seawater injection to the nuclear
reactor through the feed water system was initiated.
-From 3:37 pm on March 25th, we started injecting freshwater.
-As it is suspected that hydrogen gas is accumulated inside reactor
containment vessel, we commenced the valve opening operation concerning
injection of nitrogen gas into the reactor container vessel at 10:30 pm
April 6th and commenced injection at 1:31am April 7th.
Unit 2(Shut down)
-At approximately 6:00 am on March 15th, an abnormal noise began emanating
from nearby Pressure Suppression Chamber and the pressure within the
chamber decreased.
-From 10:10 am on March 26th, 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.
Unit 3(Shut down)
-Explosive sound and white smoke were confirmed at approximately 11:01am
March 14th. It was assumed to be hydrogen explosion.
-From 6:02 pm on March 25th, 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.
Unit 4 (outage due to regular inspection)
-At approximately 6:00 am on March 15th, we confirmed the explosive sound
and the sustained damage around the 5th floor rooftop area of the Nuclear
Reactor Building.
-At this moment, we do not consider any reactor coolant leakage inside the
reactor happened.
Unit 5 (outage due to regular inspection)
-Sufficient level of reactor coolant to ensure safety is maintained.
-At 5:00 am, March 19th, we started the Residual Heat Removal System Pump
(C) in order to cool the spent fuel pool.
-At 2:30 pm, March 20th, the reactor achieved reactor cold shutdown. At
around 5:24 pm on March 23rd, when we switched the temporary Residual
Heat Removal System Seawater Pump, it has stopped automatically. At
around 4:14 pm, March 24th we replaced the pump, and restarted cooling of
reactor at around 4:35 pm.
-At this moment, we do not consider any reactor coolant leakage inside the
reactor happened.
Unit 6 (outage due to regular inspection)
-Sufficient level of reactor coolant to ensure safety is maintained.
-At 10:14 pm, March 19th, we started the Residual Heat Removal System Pump
(B) of Unit 6 in order to cool the spent fuel pool.
-At 7:27 pm, March 20th, the reactor achieved reactor cold shutdown.
-In relation to the two seawater side pumps of the Residual Heat Removal
System, we switched the power source from temporary to permanent at 3:38
pm and 3:42 pm, Mar 25 respectively.
-At this moment, we do not consider any reactor coolant leakage inside the
reactor happened.
Operation for cooling the spent fuel pools
-From 5:07 pm to 7:24 pm on April 9th, spraying water to Unit 4 by
concrete pump vehicle was conducted.
-At 10:37 am on April 10th, the injection of fresh water into Unit 2 with
a temporary motor driven pump was initiated.
-We will conduct further water spray depending on the conditions of spent
fuel pools, if needed.
Draining water from underground floor of turbine buildings
-From 1:55 pm on April 3rd to 9:30 am on April 10th, at Unit 1,
transferring water from a condenser to condensate storage tank was
conducted.
Others
-We measured radioactive materials (iodine etc.) inside of the nuclear
power station area (outdoor) by monitoring car and confirmed that
radioactive materials level is getting higher than ordinary level. As
listed below, we have determined that specific incidents stipulated in
article 15, clause 1 of Act on Special Measures Concerning Nuclear
Emergency Preparedness (Abnormal increase in radiation dose measured at
site boundary) have occurred.
·Determined at 4:17 pm Mar 12th (Around Monitoring Post 4 )
·Determined at 8:56 am Mar 13th (Around Monitoring Post 4 )
·Determined at 2:15 pm Mar 13th (Around Monitoring Post 4 )
·Determined at 3:50 am Mar 14th (Around Monitoring Post 6 )
·Determined at 4:15 am Mar 14th (Around Monitoring Post 2 )
·Determined at 9:27 am Mar 14th (Around Monitoring Post 3 )
·Determined at 9:37 pm Mar 14th (Around main entrance )
·Determined at 6:51 am Mar 15th (Around main entrance )
·Determined at 8:11 am Mar 15th (Around main entrance )
·Determined at 4:17 pm Mar 15th (Around main entrance )
·Determined at 11:05 pm Mar 15th (Around main entrance )
·Determined at 8:58 am Mar 19th (Around MP5)
Hereafter, if the measured figure fluctuates and goes above and below 500
micro Sv/h, we deem that as the continuous same event and will not regard
that as a new specific incidents stipulated in article 15, clause 1 of
the Act on Special Measures Concerning Nuclear Emergency Preparedness
(Abnormal increase in radiation dose measured at site boundary) has
occurred. In the interim, if we measure a manifestly abnormal figure and
it is evident that the event is not the continuous same event, we will
determine and notify.
-The national government has instructed evacuation for those local
residents within 20km radius of the periphery and evacuation to inside
for those residents from 20km to 30km radius of the periphery, because it
is possible that radioactive materials are discharged.
-In total 12 fire engines are lent for the water spraying to the spent
fuel pools and water injection to the nuclear reactors by various
regional fire departments* as well as Tokyo Fire Department. Also,
instruction regarding the setting and operation of large scale
decontamination system was provided by Niigata City Fire Headquarter and
Hamamatsu City Fire Headquarter.
*:Koriyama Fire Department, Iwaki Fire Brigade Headquarters, Fire
Headquarters of Sukagawa District Wide Area Fire-fighting Association,
Yonezawa City Fire Headquarters, Utsunomiya City Fire Headquarters,
Fire Headquarters of Aizu-Wakamatsu wide area municipal association,
Saitama City Fire Bureau, and Niigata City Fire Bureau.
-At around 11:35 am April 1st, a worker fell into the sea when he got into
a barge of the U.S. Forces to repair a hose of the ship. The worker was
rescued immediately, and was not injured and not contaminated. The worker
will be checked using the whole-body counter to ensure his health.
-From April 2nd, we began to transfer the radioactive water we collected
from the Central Environmental Facility to the Unit 4 turbine building.
On April 4th, water level of the pit in the trench of Unit 3 increased by
15cm from previous day. Pathway of water flow is unknown. We can not deny
the possibility that water in the turbine building of Unit 4 flows into
the trench of Unit 3. So, we stopped transferring water to the Unit 4
turbine building to make assurance. Present water level of the pit in the
trench of Unit 3 is not changed from the time we stopped transferring,
and is being stable.
-As a countermeasure against outflow of radioactive water into the sea
near the cooling water intake at Unit 2 of Fukushima Daiichi Nuclear
Power Station, we have injected coagulant into the pit from April 5th and
we have observed stoppage of spilling of water from the crack on the
concrete lateral of the pit at 5:38 am, April 6th. We have put 6,000
litters of coagulant into the breakage and surrounding ground after
investigation of the leakage route by putting tracer into the 9 holes
drilled around electrical conduit and the pit. On April 6th, we installed
rubber boards and jigs as a countermeasure against the outflow from the
intake. We will further investigate if there is any other leakage.
-From 7:03 pm, April 4, we started to discharge to the sea approximately
ten thousand tons of the accumulated low level radioactive water in the
Central Radioactive Waste Disposal Facility. From 9:00 pm on April 4 to
6:52 pm on April 9, we conducted discharging a total of 1,500 tons of the
low level radioactive subsurface water stored in the sub drain pits of
Unit 5 and 6. The amount of discharged water was approximately 1,320 tons.
-From 3:00 pm to 4:30 pm, April 5th, in order to prevent diffusion of
radioactive contaminated water out from the site port facility to
breakwater area which is south to the power station, we began repair of
breakwater by founding the large sandbag around it to replace damaged
steel water bar. We will continue the operation to prevent diffusion.
-We will continue to take all measures to ensure the safety and to
continue monitoring the surrounding environment around the Power Station.
