Quarter Century Ago Today of Hokuriku, Japan



Heavy water leak containing radioactive material at Fugen Advanced Thermal Reactor in Tsuruga City [25-year ago today]


During a regular inspection by the Japan Nuclear Cycle Development Institute of the prototype advanced thermal reactor Fugen in Tsuruga City, Fukui Prefecture, a 35-liter leak of heavy water (water with higher specific gravity than usual, used in nuclear reactors) containing radioactive material was discovered.


The Fukui Prefecture Nuclear Safety Division announced that the radioactive tritium level in the building where the heavy water was leaking reached nearly 1,000 times than usual.

Q. What is Fugen?

Fugen was a prototype advanced thermal reactor built by the former Power Reactor and Nuclear Fuel Development Corporation (the Japan Nuclear Cycle Development Institute in 1999).


The reactor was a Japanese nuclear reactor that was using natural uranium instead of enriched uranium.


In developing a nuclear reactor, a prototype reactor is built after an experimental reactor, and a demonstration reactor is built after the prototype reactor.


In the case of the prototype reactor, Fugen, accidents repeated, including a sodium leak in 1995 and a device falling in 2010. In 2016, it was decided to decommission the reactor.


Decommissioning work is still ongoing.


The name “Fugen” comes from Fugen Bosatsu (Samantabhadra Bodhisattva), standing to the right of Buddha. The prototype fast breeder reactor, Monju, comes from Monju Bosatsu (Manjusri Bodhisattva) to the left.


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