In his book The Curve of Binding Energy John McPhee talked with Theodore Taylor about the original Orion concept (which was indeed aborted by, among other things, the test ban teaty). It was tested using conventional explosives and seemed to work quite well. There's an interesting little story in there about how they brought the idea to von Braun.

By the way, is that a GREAT title for a book, or what?

__________________
If they can get you asking the wrong questions, they don't have to worry about the answers.