Originally Posted by dyna mo

the russian tzar bomb(s). fascinating history. That detonation is where much was learned about nuclear fallout. It was a big concern but what they realized is it launched the radioactive debris so high into the sky that by the time it came down, due to its half-life, the radioactivity had dissipated.

The castle bravo detonation, which was only 15 mt, had a much worse radioactive fallout due to not reaching that far into the atmosphere.