*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.
-At approximately 10:50 am on March 24th, white fog-like steam arising
from the roof part of the reactor building was observed.
-We had been injecting seawater into the reactor, but from 3:37 pm on
March 25th, we started injecting freshwater.
-We had been injecting fresh water to the reactor using fire engines;
however we switched over utilizing temporary electrical pump at 8:32
am on March 29th.
-Some of turbine building lights were turned on April 2nd.
-We injected fresh water to the reactor by a temporary motor driven pump,
but, from 10:42am to 11:52am on April 3rd we temporarily switched the
pump to the fire fighting pump to inject fresh water to use power through
off-site transmission line. We're now injecting fresh water to the
reactor by a motor driven pump powered by off-site transmission line.
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.
-We have been injecting seawater into the reactor, but from 10:10 am on
March 26th, we started injecting freshwater (with boric acid).
-We had been injecting fresh water in to the reactor utilizing fire pump,
however, we switched over to utilizing temporary electrical pump from
6:31 pm on March 27th.
-Some of turbine building lights were turned on April 2nd.
-We injected fresh water to the reactor by a temporary motor driven pump,
but, from 10:22am to 0:06pm on April 3rd, we temporarily switched the
pump to the fire fighting pump to inject fresh water to use power through
off-site transmission line. We're now injecting fresh water to the
reactor by a motor driven pump powered by off-site transmission line.
Unit 3(Shut down)
-Explosive sound and white smoke were confirmed at 11:01am March 14th. It
was assumed to be hydrogen explosion.
-We had been injecting seawater into the reactor pressure vessel, but from
6:02 pm on March 25th, we started injecting freshwater.
-We had been injecting fresh water in to the reactor utilizing fire pump,
however, we switched over to utilizing temporary electrical pump from
8:30 pm on March 28th.
-Some of turbine building lights were turned on April 2nd.
-We injected fresh water to the reactor by a temporary motor driven pump,
but, from 10:03am to 0:16pm on April 3rd, we temporarily switched the
pump to the fire fighting pump to inject fresh water to use power through
off-site transmission line. We're now injecting fresh water to the
reactor by a motor driven pump powered by off-site transmission line.
Unit 4 (outage due to regular inspection)
-At approximately 6 am on March 15th, we confirmed the explosive sound and
the sustained damage around the 5th floor rooftop area of the Nuclear
Reactor Building.
-Some of turbine building lights were turned on March 31st .
-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 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 3:42PM, 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
-Water spray by the concrete pump truck to Unit 4 was conducted from 5:35
pm to 6:22 pm on April 5th.
-We will conduct further water spray depending on the conditions of spent
fuel pools.
·Draining water from underground floor of turbine buildings
-At 1:55 pm April 3rd, in Unit 1, water transfer from a condensate storage
tank to a suppression pool water surge-tank was initiated.
-At 5:10 pm, April 2nd, in Unit 2, water transfer from a condensate
storage tank was to a suppression pool water surge-tank was initiated.
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)
From now on, 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.
-By March 22nd, Units 1 through 6 started to be energized from the
external power source.
-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 4th, we began to transfer the radioactive water we collected
from the building of Radioactive Waste Treatment Facilities 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.
-At around 9:30 am, April 2nd, we detected water containing radiation dose
over 1,000 mSv/h in the pit* where supply cables are stored near the
intake channel of Unit 2. Furthermore, there was a crack about 20 cm on
the concrete lateral of the pit, from where the water in the pit was out
flowing into the sea. (previously announced).
-We also injected fresh concrete to the pit, but we could not observe a
reduction in the amount of water spilling from the pit to the sea.
Therefore, we started to inject the polymer (April 3rd).
-From 7:08 am to 7:11 am on April 4th, we put the tracer into the pit and
began an investigation of water flows. Additional tracer was put through
the two new holes drilled near the pit. At 2:15 pm, April 5th, it was
observed the water with tracer came out from the crack on the concrete
lateral of the pit. At 3:7 pm, April 5th, injection of coagulant from the
holes was initiated.
-There is plenty of radioactive wastewater in the turbine buildings.
Especially, Unit 2's wastewater is very highly radioactive. To store this
stably, it was decided that this needed to be transferred to the Central
Radioactive Waste Disposal Facility. However, within that facility, we
are storing ten thousand tons of low level radioactive wastewater. In
order to transfer more wastewater, we need to discharge the low level
radioactive wastewater. In addition, as low radioactive subsurface water
is piling up in sub-drain pits of Units 5 and 6 and a part of subsurface
water is running into buildings. We are concerned that important
equipment to secure the safety of reactors may be submerged. Based on
the Section 1 of the Article 64 of the Nuclear Reactor Regulation Law,
we have decided to discharge to the sea approximately ten thousand tons
of the accumulated low level radioactive water and a total of fifteen
hundred tons of the low level radioactive subsurface water stored in the
sub drain pits of Unit 5 and 6 as soon as we get ready.
-We evaluate the impact on the discharge of the low radioactive wastewater
to the sea as approximately 0.6 mSv per year per an adult if an adult
eats adjacent fish and seaweeds everyday. The amount (0.6 mSv of
effective radioactive doses per year) is one-forth of annual radioactive
dose to which the general public is exposed from nature.
-At 7:03 pm, April 4th, discharge of low radioactive wastewater
(approximately 10,000 ton in total) from Central Radioactive Waste
Disposal Facility to the sea was initiated.
-At 9:00 pm, April 4th, discharge of low radioactive subsurface water
(1,500 ton in total) from sub-drain pits of Units 5 and 6 to the sea was
initiated.
