Breeder Reactor

A breeder reactor is a nuclear reactor that generates more fissile material than it consumes, breeding new nuclear fuel from abundant but non-fissile isotopes such as uranium-238 or thorium-232. Its neutron economy is efficient enough that, beyond the neutrons needed to sustain the chain reaction, surplus neutrons are captured by fertile material loaded into the reactor and transmuted into new fissile fuel; fast breeder reactors use unmoderated fast neutrons to breed plutonium from uranium-238, while thermal breeder reactors use moderated neutrons to breed uranium-233 from thorium-232. Breeder designs looked attractive early in the nuclear era because they could make far more complete use of uranium resources, but interest declined after the 1960s once uranium reserves proved more abundant, and enrichment grew cheaper, than had been expected. Today Russia is the only country operating commercial fast breeder reactors, the sodium-cooled BN-600 and BN-800, though India, China and other countries continue development work on the technology.