How to hide a cloud? The organization of secrecy around French atmospheric nuclear testing (1957-1974)

How can one organize secrecy around an activity as remarkable, and as sensitive, as atmospheric nuclear testing? How can one control information that is –literally– carried on the wind? Based on primary sources, this article examines the original regime of secrecy organized around the French test sites between 1957 and 1974, and the issues it raises in terms of information control and democracy. It shows how the concern over the protection of “strategic secrets” around the French arsenal, though impossible to keep, was combined with one of concealing “dark secrets” –the measurements of radioactivity– thus rendering the extent of the radioactive contamination invisible.