The Integral Fast Reactor or Advanced Liquid-Metal Reactor was a design for a nuclear reactor with a specialized nuclear fuel cycle. The goals were to increase the efficiency of Uranium usage by breeding Plutonium and eliminating the need for transuranic isotopes ever to leave the site. The reactor was an unmoderated design running on fast neutrons, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). The design proceeded as far as a large-scale test that demonstrated the passive safety of the design, but was cancelled in 1994 by the US government.
This reactor is cooled by liquid sodium and fueled by a metallic 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. Key benefits of this design are:
- Enhanced safety because of the high thermal conductivity of the fuel.
- Able to withstand both a Loss of flow without SCRAM and Loss of heat sink without SCRAM [1] (http://www.anlw.anl.gov/anlw_history/reactors/ebrii_docs/ifr_safety.html)[2] (http://www.anlw.anl.gov/anlw_history/reactors/ifr.html).
- Ease of fuel fabrication. Because the sodium fills the space between the fuel and cladding, the fuel need not be precisely fabricated. The fuel is simply cast.
- Because casting is simple, the fuel can be fabricated remotely, reducing the hazards of its radioactivity.
- Reprocessing is simplified because there is no need to stringently reduce the radioactivity of the fuel. Actinides can also be incorporated into the fuel.
- Proliferation hazards are reduced by the high radioactivity of the fuel.
- Pyroprocessing and electrorefining are feasible with this fuel. This allows on site reprocessing. Two forms of waste are produced, a noble metal form and a ceramic form. Both are suitable for geological disposal.
- The waste produced contains no Plutonium or other actinides. The radioactivity of the waste decays to levels similar to the original ore in about 300 years.
Key disadvantages of this design are:
- The flammability of sodium. Sodium burns easily in air, and will ignite spontaneously on contact with water.
- Under neutron bombardment, sodium-24 is produced. This is highly radioactive, emitting an energetic gamma ray of 2.7 MeV. Half life is only 15 hours, so this isotope is not a long term hazard.
- Many environmentalists oppose all nuclear technology.
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