A breeder reactor is a [[http://www.machine-history.com/Nuclear%20Reactor|nuclear reactor]] that is designed to produce more fissile material than it uses up.
In these reactors fissile material is produced through the conversion of 238U uranium into 239P plutonium. These machines are based on fast moving neutrons by using no moderator. Some ways this is done are by cooling with liquid sodium which has good heat transfer but does not slow down the neutrons.
Fast neutrons convert the (238U) uranium isotope, which does not directly undergo fission, to (239Pu) plutonium. This 239Pu is fissile material which can be used to create a reaction either for power plants in the form of MOx or for atomic weapons. This fuel cycle has been termed the plutonium economy. Other fissionable materials can be produced in a breeder reactor like thorium-233 which decays to fission material uranium-233.
Experimental Breeder Reactor-I (EBR-I) was the first breeder reactor which operated at Idaho National Laboratory built and designed by the Argonne National Laboratory in Chicago, Ill . On Dec. 20, 1951, the first historic experiment at EBR-I began. At 1:50 p.m., the first usable amount of electricity ever generated from nuclear power began flowing from the turbine generator. Four light bulbs glowed brightly to inaugurate the birth of nuclear-generated power. The next day, the experiment was repeated, and sufficient electricity to power the EBR-I building was generated.
Some other past and present breeder reactors include France's Phenix and later Superphenix which produced electricity form 1985 to 1996. Russia's BN-600 was in operation from 1980 to 2010. Japan's Monju operated in 1994 and 1995 and is suppose to achieved criticality again in 2010.