First and foremost, I have no education or experience in space sciences beyond my affinity of following those who do. Please think twice before saying "won't work" (something like, the old school scientist will say it is impossible, and the new school scientist will prove him wrong).
I understand that the US and Soviet Union both began work on spacecraft propelled by nuclear explosions. Here is an excerpt from the Wikipedia article on Project Orion:
The vehicle and its test program would violate the Partial Test Ban Treaty of 1963 as currently written, which prohibited all nuclear detonations except those conducted underground, both as an attempt to slow the arms race and to limit the
