re: #1071 SixDegrees

Most plutonium and uranium fallout is going to hit the ground fairly quickly. But byproducts of various types can easily be sampled; you don’t even have to be nearby. Also, analysis of the seismic signature can reveal an awful lot about the bomb’s design.

That’s true. The U-235 and plutonium would not drift far. But their would be traces of daughter isotopes from the nuclear reaction. The proportions of these isotopes would be a signature of the fuel used in the warhead.