Sodium-cooled fast reactor (SFR) technology has been established over several decades and medium-scale prototype plants have been built and operated in several countries, including, e. g., France, UK, and elsewhere.

The SFR is also a Gen IV-B technology which is being put forward at both a medium — and large-size scale (Sinco, 2003). It is seen at present as mainly for the management of plutonium and other actinides and high-level waste (Overview of Generation IV Roadmap). As with all fast spectra systems, it offers an efficient utilisation of fissile and fertile materials in a closed fuel cycle. It is possible that it could be used as an electricity generator but at present capital costs are too high. A 2030-2050 timescale is again the projected timescale for the commercial SFR.