I can top that. I worked on a project for the Air Force, a "broken attow" project which is what they call an accident involving a nuclear warhead. A missile caught fire and burned, the warhead melted and they lost about 1.5 kilograms of plutonium that was washed out into a ditch by the firefighting water. We investigated the site and determined the best way to clean it up, which was to haul the contaminated soil, asphalt, and concrete to the Nevada Test Site for disposal. One of the comments we got on our report was that we didn't consider the cumulative effects of adding 1.5 kg of plutonium to the nuclear material already at the Nevada Test Site.
Which is where we've done most of the testing of our nuclear weapons.
