View of Advanced Gas-cooled Reactor (AGR), 1980s.
© Science Museum / Science & Society Picture Library
Reconstruction. In 1958 the United Kingdom Atomic Energy Authority (UKaeA) began work on the AGR, the succesor to Magnox reactors, building a prototype at Windscale, Cumbria. Like Magnox, the core of an AGR is graphite and the coolant carbon dioxide. However, the AGR operates at higher temperatures and gas presures and so it uses uranium oxide fuel clad in stainles steel. The proportion of uranium 235 which can fision in the fuel is enriched to nearly 3 per cent rather than the 0.7 per cent it is in natural uranium.