Secondary radioactive isotopes are created by nuclear explosions through nuclear spallation, basically random rejumbling of atoms; the nuclear version of free radicals. And you certainly can split every atom except hydrogen, since it only has one proton. And btw I’m no expert either, I’ve just done my own research.
Yeah, I just was answering off the top of my head. I work with several people that did underground tests and all my knowledge is based off what I’ve gleaned off of them. I’m better versed in TNT and ANFO.