(Physics) Any of several devices that maintain and control a nuclear reaction for the production of energy or artificial elements; SYN. reactor.
Device for producing nuclear energy in a controlled manner. There are various types of reactor in use, all using nuclear fission. In a gas-cooled reactor, a circulating gas under pressure (such as carbon dioxide) removes heat from the core of the reactor, which usually contains natural uranium. The efficiency of the fission process is increased by slowing neutrons in the core by using a moderator such as carbon. The reaction is controlled with neutron-absorbing rods made of boron. An advanced gas-cooled reactor (AGR) generally has enriched uranium as its fuel. A water-cooled reactor, such as the steam-generating heavy water (deuterium oxide) reactor, has water circulating through the hot core. The water is converted to steam, which drives turbo-alternators for generating electricity. The most widely used reactor is the pressurized-water reactor, which contains a sealed system of pressurized water that is heated to form steam in heat exchangers in an external circuit. The breeder reactor has no moderator and u
ses fast neutrons to bring about fission; it produces more fuel than it consumes.