Fast breeder reactor

A fast breeder reactor is  nuclear power reactor in whose design tradeoffs have been made not to produce the ideal heat for power generation, but to produce reasonable heat but also a substantial amount of high-energy neutrons that will make ("breed") potential nuclear fuel of an appropriate plutonium isotope. Economically, it seems attractive when a reactor can produce 30 percent more fuel than it burns.

There has been hesitancy to use this design, over concerns on weapons-grade plutonium becoming too widely available. Only two, neither of which is operational, has been built in the U.S.