George Dyson’s 2003 Project Orion: The True Story of the Atomic Spaceship is the biography of an atomic rocket that never was. Strike that, the atomic rocket that never was. Atomic rockets like NERVA or DUMBO may have used the power of the atom, but their approach was not so very different from conventional chemical rockets and their performance not so much better. Orion promised delta vees more than an order of magnitude better than NERVA at its best.
All it asked in return for its astounding performance was a studied tolerance for proximity to nuclear explosions. Repeated explosions.