*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.
-From 7:35 pm, April 12th, we started transferring the high level
radioactive puddle water in the trench of the turbine building to the
condenser by an underwater pump.
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 0:30 am to 6:57 am on April 13th, we conducted water spraying to
Unit 4 by the concrete pumping vehicle.
-We will conduct further water spray depending on the conditions of spent
fuel pools, if needed.
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.
-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. To be
safe, we checked the worker using the whole-body counter and confirmed
that there was no internal exposure.
-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.
-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. We are confirming the
amount of discharged water. From 9:00 pm on April 4, 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 1,323 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.
From 8:45 am to 10:45 am, April 11, in order to prevent water containing
radioactive material from spilling from a plant's port to the sea, we
conducted works to install 120m wide double silt fences around a
breakwater on the south of the station.
-Below is the status of TEPCO's major facilities due to the 7.1 magnitude
earthquake centered in the Fukushima-Hama-dori earthquake which occurred
at approximately 5:16 pm, April 11th 2011. Due to the shutdown of the
off-site power, water injection to the reactor of the units 1-3 was
suspended and was resumed at approximately 6:04 pm after restoration of
off-site power. No abnormalities were detected in the parameter of each
of the Units. Nitrogen gas injection to the reactor containment vessel
of Unit 1 was suspended and resumed at 11:34 pm. In addition, we
confirmed that the water level of Units 1-3's pit did not change
significantly and there were no injured workers inside of the buildings.
-In regard to the earthquake occurred at 2:07 pm on April 12th with a
magnitude of 6.3, epicenter in the Fukushima-Hama-dori, no trouble were
detected in the plant units after the earthquake. Safety of workers has
also been confirmed.
-At approximately 6:38 am, April 12th, a fire broke out at the
distribution switchboard containing batteries located in the sampling
equipment switchbox situated close to the south water discharge channel
for Units 1-4. The self defense fire fighting team began extinguishing
this fire soon after it broke out. At approximately 6:45 am, this
incident was reported to the Futaba fire authorities. The Futaba fire
authorities confirmed the fire was extinguished as a result of site survey
as of 9:12 am. This incident did not impact the external release of
radioactive substances and the cooling capability of the reactor. The
data taken from the monitoring of the environment in the area did not
change.
-On April 12th, in order to confirm the conditions of the fuels stored in
the spent fuel pool of Unit 4, we sampled the water in the spent fuel
pool. We will be conducting nuclide analysis on these samples.
-We will continue to take all measures to ensure the safety and to
continue monitoring the surrounding environment around the Power Station.
