Integral fast reactor

The integral fast reactor (IFR, originally advanced liquid-metal reactor) is a design for a nuclear reactor using fast neutrons and no neutron moderator (a "fast" reactor). IFR is distinguished by a nuclear fuel cycle that uses reprocessing via electrorefining at the reactor site.

IFR development began in 1984 and the U.S. Department of Energy built a prototype, the Experimental Breeder Reactor II. On April 3, 1986, two tests demonstrated the inherent safety of the IFR concept. These tests simulated accidents involving loss of coolant flow. Even with its normal shutdown devices disabled, the reactor shut itself down safely without overheating anywhere in the system. The IFR project was canceled by the US Congress in 1994, three years before completion.

The proposed Generation IV Sodium-Cooled Fast Reactor is its closest surviving fast breeder reactor design. Other countries have also designed and operated fast reactors.

S-PRISM (from SuperPRISM), also called PRISM (Power Reactor Innovative Small Module), is the name of a nuclear power plant design by GE Hitachi Nuclear Energy (GEH) based on the Integral Fast Reactor.

The IFR is cooled by liquid sodium or lead and fueled by an alloy of uranium and plutonium. The fuel is contained in steel cladding with liquid sodium filling in the space between the fuel and the cladding. A void above the fuel allows helium and radioactive xenon to be collected safely without significantly increasing pressure inside the fuel element, and also allows the fuel to expand without breaching the cladding, making metal rather than oxide fuel practical.

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