Magnox Reactor

Magnox is a type of nuclear power and production reactor designed and built in the United Kingdom, running on natural uranium with graphite as the moderator and carbon dioxide gas as the coolant, placing it within the wider class of gas-cooled reactors. Its name comes from the magnesium-aluminium alloy used to clad the fuel rods inside the reactor, and like most other Generation I reactors it was designed for the dual purpose of producing electrical power and plutonium-239 for Britain's nascent nuclear weapons programme. Graphite's efficiency as a moderator let Magnox run on natural, unenriched uranium fuel, unlike the more common commercial light-water reactor, which requires slightly enriched uranium; carbon dioxide cools the graphite core, which is otherwise prone to oxidizing in air, and is pumped to a heat exchanger to raise steam for a conventional turbine, while the core's open design allows fuel elements to be added or removed while the reactor keeps running. The dual-use design let the United Kingdom build up a large stockpile of reactor-grade plutonium with the aid of the B205 reprocessing facility, though despite later design improvements Magnox reactors were never able to match the higher efficiency and fuel burnup of pressurized water reactors.