The gas-cooled fast reactor (GFR) system features a fast-spectrum helium-cooled reactor and closed fuel cycle. Like thermal-spectrum helium-cooled reactors such as the Gas Turbine Modular Helium Reactor (GT-MHR) and the Pebble Bed Modular Reactor (PBMR), the high outlet temperature of the helium coolant makes it possible to generate electricity, hydrogen or process heat with high conversion efficiency. The GFR uses a direct-cycle helium turbine for electricity (45% efficiency at 850ºC), and process heat for thermochemical production of hydrogen. Optional coolants (e.g., supercritical CO2) may offer high thermal efficiency (45%) using a direct cycle, while maintaining lower coolant temperatures (at 550ºC). The GFR' s fast spectrum makes it possible to utilize available fissile and fertile materials (including depleted uranium from enrichment plants) several orders of magnitude more efficiently than thermal spectrum gas reactors with once-through fuel cycles. Furthermore, through the combination of a fast neutron spectrum and full recycle of actinides, GFRs minimize the production of long-lived radioactive waste isotopes, and can be designed for minor actinide management from spent fuel. The GFR concept targets an integrated, on-site spent fuel treatment and refabrication plant.