On the difficulty of clandestinely building an atomic bomb

Wherever breeder reactors and reprocessing are discussed there is a problem of serious impact: the risk of proliferation, which means the spreading of nuclear weapons. But not only in the case of these two components of a future fuel cycle are there proliferation paths, points at which fissionable material might possibly be diverted. They exist from the uranium ore mine up to the depositing of burnt out fuel elements. However, the path from possessing uranium to the finished bomb is a long one, and it is paved with very great technical difficulties. (orig.)