March 12 TEPCO reported that the cooling system for reactors 1, 2 and 4 at the plant had exceeded 100 °C and that the "pressure suppression function was lost". Tepco has announced it was preparing for pressure release in the containments of the units.
TEPCO reported at 06:00:00 pm Saturday March 12, Eastern Time
Fukushima Daini Nuclear Power Station:
Units 1 to 4: shutdown due to earthquake
* The national government has instructed evacuation for those local
residents within 10km radius of the periphery.
* At present, we have decided to prepare implementing measures to reduce
the pressure of the reactor containment vessel (partial discharge of air
containing radioactive materials) in order to fully secure safety.
These measures are considered to be implemented in Units 1, 2 and 3 and
accordingly, we have reported and/or noticed the government agencies
As of 8:35 Eastern Time 12 March, the IAEA has reported that venting has not occurred at Units 1, 2, and 4 at the Fukushima Daini nuclear power plant. It is reported that Units 1, 2, and 4 retain off-site power.
In the 10-kilometre radius around Fukushima Daini an estimated 30,000 people have been evacuated. Full evacuation measures have not been completed.