But as nuclear weapons proliferated people began to understand the unbreakable connection between nuclear power and nuclear weapons. After mining the uranium mineral is refined to uranium oxide, called yellowcake. Its concentration in yellowcake is only 0.7 per cent. To make bomb-grade fuel yellowcake is enriched to 90 per cent. In the diffusion process hex vapour passes through thousands of membranes along a two kilometre tunnel.
Centrifuge plants are compact and so readily concealed.
Uranium is the key to nuclear weapons. Periodically spent-fuel is removed from reactors and after storing for a year or more it can be treated in a reprocessing plant to recover the plutonium. One large reactor produces 250 kilograms of plutonium each year. With so much plutonium around in the world today some has found its way on to a black market. Nations were more concerned with developing nuclear industry than with the effectiveness of safeguards.