On March 11 2011, turbines and reactors of Fukushima Daini Nuclear Power
Station Units 1 to 4 (Boiling Water Reactors, rated output 1,100 Megawatts)
that we had been constantly operating at rated thermal output were
automatically shut down at 2:48 pm due to the Tohoku-Chihou-Taiheiyou-Oki
Earthquake occurred at 2:46 pm.
Due to the affect of tsunami accompanied by the earthquake, on each unit
of 1, 2 and 4 has lost its cooling function of reactor core and as the
temperature of pressure suppression chamber has exceeded 100°C (which is
relevant event under the Act on Special Measures Concerning Nuclear
Emergency Preparedness), Declaration of a Nuclear Emergency Situation was
issued by the Prime Minister on March 12.
Emergency response measures were taken such as restoration of electric
motors and recovery of function of residual heat recovery pumps and cold
shut down has been achieved for each of the unit by March 15. Thereafter,
emergency response measures had been continuously taken such as
restoration of power supply functions and diversification of residual
heat recovery system and we have endeavored to maintain stable cold shut
down status of the plant.
Implementation status of emergency response measures were confirmed by
the government that it is in the condition to continuously maintain
stable cold shut down status of the plant and on December 26, declaration
of cancellation of a Nuclear Emergency Situation was issued by the Prime
Minister.
In accordance with the declaration, we will take measures for restoration
from nuclear emergency to stably maintain cold shut down status of each
unit and endeavor to enhance stable condition of the plant.
We will announce the plant status as of 3:00 pm of today as stated below
and with attachment.
‹Unit 1>
○ Inspection of inside of the primary containment vessel
At 10:06 am on December 27, for the purpose of determining soundness of
reactor primary containment vessel of unit 1 and internal facilities,
airlock* for the workers was opened and started sight survey.
We plan to conduct same inspection for unit 2 and 3 accordingly.
(Previously announced on December 21 about the results of visual check
inside the reactor containment vessel of Unit 4)
* airlock for the workers
hatch to enter into the primary containment vessel
‹Others>
○ onset of Noro virus to the employee of TEPCO
On December 26, one of TEPCO's employee who was worked at Fukushima
Daini Nuclear Power Station was newly diagnosed as Noro virus.
Disinfecting of the working environment was conducted. We will
continuously promote disinfection method such as hand washing and
gargle.
Appendix: Plant Status of Fukushima Daini Nuclear Power Station (PDF 11.2KB)