Can’t we just send up the propulsion system and the fuel separately? So like, ya, either could fail, but one is just some fancy equipment being g destroyed and the other is…unert uranium or plutonium coming down, needing to be cleaned up but not in a particular dangerous mode. Then once in orbit and the risk of crashing into earth is much less, put them together, fire up the reactor and go?

I suspect that the fuel separate from the reactor is still a major risk.