15.51. The advanced liquid-metal-cooled reactor (ALMR) design is based on the PRISM (Power Reactor, Innovative Small Module) concept de­veloped by the General Electric Co., while the fuel system is based on the IFR (integral fast reactor) concept developed by Argonne National Lab­oratory [6,7]. Liquid-metal-cooled fast breeder reactors have attracted the attention of reactor designers since the earliest days of the nuclear power industry because of their ability to transform fertile uranium-238 into fissile plutonium-239 efficiently using fast neutrons (§10.65). Furthermore, so­dium cooling allows the reactor to be at atmospheric pressure. However, commercial development of such systems was deferred in the early 1980s as a result of proliferation concerns and economic conditions at the time.

15.52. During recent years, the outstanding performance of new me­tallic fuels in EBR-II, a 20-MW(el) fast reactor that has been operating very satisfactorily since 1961, resulted in the development of the IFR con­cept, which features an inherently safe core with passive features and proliferation-resistant on-site fuel recycling. The modular approach offers the flexibility, standardization, and construction economies described pre­viously for other advanced passive systems. Although funding for continued development appeared uncertain in 1994, the concept is described briefly here as an example of a fast-reactor option with future potential.