Antinuclear

The Japanese government is moving toward decommissioning the Monju prototype fast-breeder nuclear reactor in Tsuruga, Fukui Prefecture. The Mainichi answers common questions readers may have about what kind of reactor Monju is, and the state of international research on other fast-breeder reactors.

Question: The Monju reactor is supposedly a power generating device, but how does it work?

Answer: The reactor uses one of three high-speed neutrons that are released when plutonium-239 undergoes nuclear fission, causing more plutonium-239 to undergo nuclear fission and creating heat. The other two neutrons are collided with uranium-238 — which is not usable by normal nuclear reactors — to create more plutonium-239. The reactor is called a “fast-breeder” because it uses “fast” neutrons to “breed” more nuclear fuel.

Q: What were the original research objectives at Monju?

A: Generally, the development process of fast-breeder reactors is to create an experimental reactor followed by a prototype reactor…