Magnox

Magnox reactors take their name from the magnesium alloy of the cladding around the natural uranium metal fuel. Calder Hall, in 1956, was the world's first commercial nuclear power station, though its main mission was producing military plutonium. Twenty-six reactors were built in the United Kingdom, plus Tokai 1 in Japan and Latina in Italy.

Their low temperature and minimal power density made them enormous for their output. The last one, Wylfa 1, closed in 2015. Decommissioning the graphite buildings will take decades.