> A dirty bomb remains viable with partially enriched materials.

A dirty bomb is basically Hollywood nonsense, and wouldn't use uranium to begin with because it isn't very radioactive.

The premise is that you put radioactive materials into a conventional explosive to spread it around. But spreading a kilogram of something over a small area is boring because you can fully vaporize a small area using conventional explosives, spreading a kilogram of something over a large area is useless because you'd be diluting it so much it wouldn't matter, and spreading several tons of something over a large area is back to "you could do more damage by just using several tons of far cheaper conventional explosives".

Also anything that is dangerous enough to actually be scary in dirty bomb form, like Cobalt-60, would be impossible to handle without providing a lethal dose of radiation to anyone working with he material within minutes if not seconds (presumably a reasonablely large & dangerous amount of this material is involved). At least, not without incredibly expensive equipment. And by the time you factor in those prerequisites it's just not worth it.

The toxicity of the Uranium would be a bigger problem than the radioactivity