High Temperature Gas-Cooled Reactors: Design Features, Potential and Challenges

Over a period spanning more than half-a century, the High-Temperature Gas-cooled Reactor (HTGR) design has evolved from early experimental prototypes with single-coating fuel to more recent modular designs featuring TRISO fuel and a Brayton cycle gas turbine design, promising enhanced safety and improved economics. In this paper, the current status of the technology is reviewed, starting with a brief introduction and a descriptive history of the evolving design. This is followed by an overview of the special fuel and core design aspects, including core physics, thermal-hydraulics, reactivity control and fuelling schemes. An overview of safety performance is also presented, followed by an outline of the various power conversion unit layouts, the Brayton cycle main characteristics and the potential process heat applications of this particular design. A brief overview of the challenges facing HTGR designs and the status of research and development work is also presented. (authors)