[curmudgeonII]

If the damn thing explodes [which has happened with some degree of frequency with rockets], how big an area is it going to contaminate?

[RightWhale]

If the damn thing explodes [which has happened with some degree of frequency with rockets], how big an area is it going to contaminate?

If it explodes, that would happen in space, so it wouldn't contaminate an area.

[Brett66]

It will only be used in LEO, not in the atmosphere. It's power source will probably be a nuclear reactor, but the propulsion system itself is a magnetically powered plasma stream. It would probably be safer than a nuclear sub or aircraft carrier in terms of it's operation.

[Frank_Discussion]

You really are a curmudgeon! The RTG's in the systems proposed are very low volume plutonium sources, so even if you did breach the casings, it is a very small amount. The fission-powered energy sources are a bit more dicey, but still nothing on par with Chernobyl, etc.

The rockets they will power, BTW, do not release radioactivity at all at any rate. Hence, if the engines blew, it wouldn't be a contaminating source in themselves.