The Gas Fast Reactor (GFR) Survey of Materials Experience and R&D Needs to Assess Viability

The GFR system features a fast-spectrum, gas-cooled reactor and closed fuel cycle. The GFR reference design is a helium-cooled system operating at 7 MPa with an outlet temperature of 850°C that utilizes a direct Brayton cycle turbine for electricity production and provides process heat for thermochemical production of hydrogen. Through the combination of a fastneutron spectrum and full recycle of actinides, GFRs will be able to minimize the production of long-lived radioactive waste isotopes and contribute to closing the overall nuclear fuel cycle. Two alternate system options are currently being considered that utilize a supercritical CO2 (SCO2) Brayton cycle for power conversion to maintain good efficiencies at reduced outlet temperatures. One of the alternate system options incorporates a helium-cooled primary circuit, the other an S-CO2-cooled primary circuit. The largest materials challenge for the GFR will be to select and qualify materials for the core and reactor internals structures, since graphite use will be severely restricted due to its heavy moderation of the neutron spectrum. Much of the GFR balance of plant will be able to utilize materials being evaluated or qualified for the Next Generation Nuclear Plant, though a number of items specific to the operation of the GFR will need to be evaluated. The materials R&D plan for the GFR will examine those materials viability issues expected to potentially limit the GFR in time to allow a decision on the overall viability of the GFR system concept to be made by 2010. Potential showstoppers will be identified and resolved. The information generated during this stage of the R&D is sufficient for the conceptual design of a prototype. The extended research required to provide the extensive databases needed to qualify primary GFR candidate materials for final design and licensing will be addressed subsequently, during a materials qualification program phase. While there are significant materials development and qualification needs for the GFR, existing materials have been identified that have the potential to meet the requirements of all the GFR components and subsystems. The total cost estimate for viability R&D of the materials needed for the GFR is about $96 million dollars. These direct costs may be reduced through collaborative research with related domestic and foreign research programs.