Wedoany.com Report-Dec.24, Water containing radioactive substances leaked at the decommissioning site of the Fugen nuclear reactor in Fukui Prefecture, central Japan, on Tuesday, according to reports from local media and the Japan Atomic Energy Agency (JAEA).

The incident occurred at the prototype advanced thermal reactor, also known as Fugen, located in Tsuruga City, Fukui Prefecture. During dismantling work in an auxiliary building, approximately 20 milliliters of water containing radioactive tritium leaked from piping associated with equipment for analyzing heavy water.

The leak happened when a pipe was cut as part of ongoing decommissioning activities at the facility, which has been in the process of being dismantled since its shutdown.

The JAEA reported that tritium concentration levels inside the containment area rose to about 10 times the legal reporting threshold, prompting notification to the Nuclear Regulation Authority.

Three workers were present nearby at the time. They immediately left the site, and authorities confirmed no internal radiation exposure occurred, such as from swallowing or inhaling the water. Detailed examinations are underway to check for any possible external exposure from water splashing on the skin or through other means.

No radioactive materials were detected outside the controlled area of the facility. Monitoring posts measuring radiation levels within and around the site showed no abnormalities, and no impact on the external environment has been confirmed.

The Fugen reactor, a heavy water-moderated, boiling light water-cooled prototype, underwent decommissioning following its operational phase. The current work focuses on safely dismantling structures while managing residual radioactive materials, including tritium.

Authorities emphasized that the small volume of the leak and the containment measures in place, such as a partitioned work area, helped prevent any spread beyond the immediate site.

This event is being managed under standard protocols for decommissioning nuclear facilities, with ongoing monitoring to ensure worker safety and environmental protection.