A sodium-cooled fast reactor (SFR) is a type of nuclear reactor that uses liquid sodium as a coolant. This design allows for efficient heat transfer and enables the reactor to operate at higher temperatures compared to traditional water-cooled reactors. SFRs utilize fast neutrons to sustain the nuclear fission process, which can improve fuel efficiency and reduce nuclear waste. SFRs are part of a broader category of reactors known as fast reactors, which can utilize a variety of fuels, including plutonium and uranium. They are considered a promising technology for advanced nuclear power systems, contributing to sustainable energy solutions and the potential for closed fuel cycles.