Or this: https://en.m.wikipedia.org/wiki/Acerinox_accident https://en.m.wikipedia.org/wiki/Acerinox_accident In May 1998, a caesium-137 source managed to pass

Or this: https://en.m.wikipedia.org/wiki/Acerinox_accident https://en.m.wikipedia.org/wiki/Acerinox_accident In May 1998, a caesium-137 source managed to pass through the monitoring equipment in an Acerinox scrap metal reprocessing plant in Los Barrios, Spain. When melted, the caesium-137 caused the release of a radioactive cloud. The Acerinox chimney detectors failed to detect it, but it was eventually detected in France, Italy, Switzerland, Germany and Austria. The radioactive levels measured were up to 1000 times higher than normal.