Generation IV nuclear reactors: The gas-cooled fast reactor (GFR)

The Gas-Cooled Fast Reactor (GFR) has been chosen as one of six candidates for development as a Generation IV nuclear reactor based on: its ability to fully utilize fuel resources; minimize or reduce its own (and other systems) actinide inventory; produce high efficiency electricity; and the possibility to utilize high temperature process heat. Current design approaches include a high temperature (≥ 850°C) helium cooled reactor using a direct Brayton cycle, and a moderate temperature (550°C-650°C) helium or supercritical carbon dioxide cooled reactor using direct or indirect Brayton cycles. These design choices give thermal efficiencies approaching 45% to 50%, and have turbomachinery sizes that are more compact compared to steam plants. However, there are challenges associated with the GFR, which are the focus of current research. This includes safety system design for decay heat removal, development of high temperature/high fluence fuels and materials, and development of fuel cycle strategies.