Magnox

Magnox is the name given to a magnesium–aluminium alloy used as fuel cladding in Britain’s early gas-cooled, graphite-moderated nuclear reactors, and to the class of reactors that used that cladding. The alloy was developed to clad natural uranium metal fuel and to minimize neutron absorption in the early reactor designs. When irradiated, Magnox cladding becomes radioactive and, in the carbon dioxide coolant environment, can corrode over time, forming oxide scales and releasing hydrogen.

The Magnox reactors are gas-cooled and graphite-moderated, using natural uranium metal fuel enclosed in Magnox cladding. They were constructed and operated from the 1950s into the 1970s and early 1980s, with eleven units at eight sites in the United Kingdom. The fleet represented the first generation of commercial nuclear power in the UK and contributed to the country’s early electricity supply, while also providing materials for defense research in the broader nuclear programme.

Decommissioning and legacy: All Magnox reactors have been shut down. Decommissioning is led by Magnox Ltd, under contract to the Nuclear Decommissioning Authority. The program involves defueling, dismantling facilities, treating and disposing of irradiated fuel and radioactive waste, and restoring sites, a process expected to continue for many decades.

See also: Gas-cooled reactors, Nuclear power in the United Kingdom, Nuclear Decommissioning Authority, Magnox Electric (historical operator).