Experimental Breeder Reactor-II (EBR-II) was a sodium-cooled fast reactor designed, built and operated by Argonne National Laboratory at the National Reactor Testing Station in Idaho. It was shut down in 1994. Custody of the reactor was transferred to Idaho National Laboratory after its founding in 2005.

The integral fast reactor is a design for a nuclear reactor using fast neutrons and no neutron moderator. IFR would breed more fuel and is distinguished by a nuclear fuel cycle that uses reprocessing via electrorefining at the reactor site.