Project Orion is outdated anyway, we have technology like laser detonation and computer coordination such that you can detonate tiny fuel pellets continuously rather than bouncing off of entire bombs with a looney tune pogo stick arrangement.
The standards for propulsion are lower than that for electric power; you don't really need a continuous nuclear explosion flung out the back to be net-positive electrically, you just need it to happen.
https://en.m.wikipedia.org/wiki/Project_Daedalus