Comment by M95D

Nuclear explosions don't have "reactants". There's just a few Kg of Uranium or other fuel and a little conventional explosive to trigger it, and that's all. That's not enough mass to propell anything of significant size outside of atmosphere. The speed at which the mass is ejected from the engine counts, of course, but a nuke won't give the same speeds as an ion engine for example.

Aldebaran spacecraft proposed to "intake" air. But it's mass means it would have to intake A LOT of air. And that engine, as described in the article, doesn't seem to compress the air before each bomb expands it. I don't think it would work.

IIRC, the Orion project proposed to wrap each bomb in one ton of polypropylene. It would provide mass and also reduce radiation fallout.