Modular high-temperature gas-cooled reactor

The co-operative industry-government development of the high-temperature gas-cooled reactor (HTGR) in the USA has focused for almost 20 years on large nuclear systems with individual unit outputs from 450MWe to 1300MWe. In 1984, in response to initiatives from the US Congress and the utility industry, the programme was redirected to concentrate effort on small, modular units which could be installed in increments as small as 100MWe. Design of the modular HTGR has been guided by specific, quantified, utility and user requirements which incorporate established regulatory requirements for the protection of the public as well as special requirements for enhanced safety and investment protection. The key requirements are listed. Each module consists of a reactor vessel and a steam generator vessel connected by a coaxial cross duct. The reactor design is illustrated. The annular core and control rod layout is shown and the fuel components are explained. The steam generator and coolant circuits are described. Forecasts of the economics of the modular HTGR indicate that it will be economically competitive. (author)