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, improving its thermal efficiency. SFRs utilize fast neutrons to sustain the nuclear fission process, which allows them to use a wider range of nuclear fuels, including recycled materials. SFRs are part of the Generation IV nuclear reactor designs, aimed at enhancing sustainability and safety in nuclear energy. They can help reduce nuclear waste and improve fuel utilization, making them a promising option for future energy needs.