Here's a classic TED talk by George Dyson, where he shares his father Freeman's notes on reclassified Project Orion: A Cold War spaceship as large as a Marriott hotel powered by 20 kiloton nukes.
From my earlier post:
Given the time frame, the planners on the Orion had even built in defense systems meant to retaliate against the Russians. This project was the first contract funded by DARPA. In this video, George also steps through passenger acceleration profiles, emergency plans if Orion failed to clear the atmosphere and the not-so-cool 700 rads of radiation you'd get while riding it. George's final take? If an asteroid headed for our planet, an Orion type ship is one of the only emergency plans that NASA could depend on, "off the shelf." And that's why NASA bought roughly 1700 pages of the notes he collected on Orion from him.
Get Me Off This Rock: This week, we're celebrating the dream of human life in space.