A steam leak was detected early Friday morning at Unit 3 of the Mihama Nuclear Power Plant in Fukui Prefecture, central Japan, according to the operator Kansai Electric Power Company (KEPCO).

The incident occurred at around 4:10 a.m. local time, when a steam leak was detected near the unit’s high-pressure turbine section. Approximately 15 minutes later, workers manually shut down the reactor.

KEPCO stated that the steam released did not contain radioactive substances.

Unit 3 of the Mihama Nuclear Power Plant began operation in 1976. It was shut down following the 2011 Fukushima nuclear disaster and resumed operation in 2021.