Gas-Cooled Reactor

A gas cooled reactor is a nuclear reactor design that uses graphite to moderate its neutrons and a gas, either carbon dioxide or helium in the designs still operating, to carry heat away from the reactor core, rather than the water used by most reactors worldwide. Britain and France developed the technology through the 1950s because it could run on natural, unenriched uranium at a time when enriched uranium was controlled solely by the United States and the Soviet Union. The United Kingdom built 28 first generation Magnox reactors between 1956 and 2015 and 15 second generation Advanced Gas Cooled Reactors from 1962 onward, while France operated 10 of its own UNGG gas cooled reactors between 1956 and 1994. Gas cooled designs ultimately lost the commercial competition to light water reactors, though helium cooled high temperature variants, including pebble bed and prismatic block designs, remain in active development, with China HTR-10 research reactor operating since 2003.