This is an experimental fast-breeder reactor built in Tsuruga, Fukui Prefecture. In light water reactors, the uranium combustion efficiency is poor, and the introduction of a fast-breeder reactor makes it possible to effectively reburn the residual uranium and plutonium that is produced in the reactor. In Japan, where nuclear fuel recycling is the basic policy for nuclear energy, effective use of limited uranium resources is essential. However, during a trial run of Monju in 1995 there was a sodium leak accident, and operations are currently suspended.P>