a notable incident occurred at Kansai Electric Power Co.'s No. 3 reactor at the Mihama Nuclear Power Plant in Fukui Prefecture. Workers identified a steam leak around 4:10 AM, prompting an immediate manual shutdown of the reactor about 15 minutes later as a precautionary measure.

According to the utility, the steam leak did not contain any radioactive material, ensuring that there was no impact on the external environment. However, the timeline for when the reactor, which began operations in 1976, will be restarted remains uncertain.

The No. 3 unit holds significance as it became the first reactor in Japan to operate beyond 40 years since new regulations were instituted after the 2011 Fukushima Daiichi nuclear disaster. While standard regulations limit a reactor's operational life to 40 years, extensions of up to 20 years can be approved by regulators.

The situation at the Mihama plant has drawn attention as decommissioning work progresses on two older reactors, in line with broader safety measures implemented across Japan's nuclear facilities since the Fukushima incident.

Kansai Electric Power Co. continues to evaluate the technical aspects of the steam leak while managing safety inspections at the plant. The incident raises ongoing concerns regarding the safety and reliability of aging nuclear infrastructure in Japan.