Current Status of VHTR Technology Development

High Temperature Gas-cooled Reactors (HTGRs) featuring particle fuel reached the stage of commercial deployment in the mid-1980s with the Fort St.Vrain and Thorium HochTemperatur Reaktor feeding electricity to the grids in the United States and West Germany, respectively. The technology was then adopted by Japan and China with the operation of the High Temperature Test Reactor in Oarai, Japan and the High Temperature Reactor (HTR-10) in China. Increasing the outlet temperature of the HTGR to even higher temperatures above 900 C will improve the thermodynamic efficiency of the system and enable application of a new class of gas reactor, the very high temperature reactor, to provide process heat, electricity, and hydrogen to chemical industries with the attendant benefits of improved energy security and reduced CO2 emissions. However, the increase in coolant outlet temperature presents a number of technical challenges associated with fuel, materials, power conversion, and analysis methods for the reactor and hydrogen production. The U.S. Department of Energy is sponsoring a broad program of research and development with a goal of addressing the technical challenges over a broad range of outlet temperatures as part of the Next Generation Nuclear Plant Project. This paper describes the research and development activities that are currently underway to realize the technologies needed for an HTGR that features outlet temperatures of 750 to 950 C.