One of the reactors at Tokyo Electric Power Co.'s Kashiwazaki-Kariwa Nuclear Power Station in Niigata Prefecture automatically shut down Friday after the generator providing electricity to the reactor failed, Tepco said.
Tepco said there is no risk of radioactive leakage or other environmental damage due to the 3:11 a.m. shutdown of the plant's No. 1 reactor, a 1.1 million-kw boiling-water reactor put into operation in 1985.
Electricity from the generator leaked into the soil, which is normally an insulator, triggering a system to protect and halt the generator, according to the utility.