Today at 2:46PM, turbines and reactors of Tokyo Electric Power Company's
Fukushima Daini Nuclear Power Station Units 1 to 4 (Boiling Water Reactor,
rated output 1,100 Megawatts) that had been operating at rated power
automatically shutdown due to the Miyagiken-oki Earthquake.
Currently, reactor water level for Units 1 to 4 is maintained by injecting
water into the reactors by the Reactor Core Isolation Cooling System.
The reactors are maintained at a subcritical condition.
For Unit 1, the emergency core cooling system automatically started up
due to increase in the reactor containment pressure assumed to be caused
by leakage of reactor coolant in the reactor containment.
Hence, at 5:35PM, it was decided that a specific incident stipulated in
Article 10, Clause 1 of the Act on Special Measures Concerning Nuclear
Emergency Preparedness *1 has occurred.
At 5:50PM, pursuant to the Act, relevant governmental institutions were
notified of the incident.
TEPCO is taking measures to reduce the pressure of the reactor containment.
Impact to safety and external environment:
Water level to cool the irradiated nuclear fuel in the reactor core is
maintained at this moment.
Indication of the monitoring posts installed in the periphery of the power
station is no different from usual and thus no radiation impact to the
external environment is confirmed at this moment.
We will continue to monitor in detail the possibility of discharge of
radioactive material from exhaust stacks and coolant water discharge canal.
*1 Specific Incident Stipulated in Article 10, Clause 1 of the Act on
Special Measures Concerning Nuclear Emergency Preparedness
The objective of the Act on Special Measures Concerning Nuclear
Emergency Preparedness is to protect the welfare, physical wellbeing
and property of Japan's citizens. To this end, when accidents and
equipment breakdown have reached certain levels at nuclear power plants,
the Act obligates us to notify the nation, prefectures, cities and towns
in order for them to take necessary actions and to grasp information in
a timely manner.
Notifications are issued out under circumstances such as when the nuclear
reactor cannot be shut down and/or when the water supply to the reactor
is cut off.
*2 Monitoring Post
Equipment to measure the radiation level in the atmosphere. Seven units
are installed in the periphery of the power station.