On this day 21 years ago a nuclear reactor near the Ukraine city of Chernobyl suffered a steam explosion and a nuclear meltdown. Winds spread the radioactive fallout over thousands of square kilometres. Now, risky new nuclear reactors are under construction in Europe, but not on this day. Not if we can help it. Activists are occupying cranes and using trucks to block the entrance at the construction site of a dangerous new type of reactor in France.