Gas-Cooled Fast Reactor (GFR)
The Gas-Cooled Fast Reactor (GFR) system features a fast-spectrum, helium-cooled reactor and closed fuel cycle. The main characteristics of the GFR are: a self-generating core (i.e., conversion ratio = 1) with a fast neutron spectrum, robust refractory fuel, high operating temperature, direct energy conversion with a gas turbine, and full actinide recycling (possibly with an integrated, on-site fuel reprocessing facility).
Several fuel forms are candidates that hold the potential to operate at very-high temperatures and to ensure an excellent retention of fission products: composite ceramic fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations may be based on prismatic blocks, pin- or plate-based assemblies.
The GFR is primarily envisioned for missions in electricity production and actinide management, although it may be able to support hydrogen production as well. The GFR design will utilize a direct-cycle, helium turbine for electricity and process heat for production of hydrogen. Through the combination of a fast-spectrum and full recycle of actinides, the GFR minimizes the production of long-lived radioactive waste. The GFR's fast-spectrum also makes it possible to use available fissile and fertile materials (including depleted uranium) considerably more efficiently than thermal-spectrum gas reactors with once-through fuel cycles.