Nuclear RTGs are a reasonable solution for power generation in the kW range if you could have a bank of them. The benefits are that they're not particularly radioactive (when enclosed) and they also generate copious amounts of heat as a byproduct. I think one is used in the Martian?
The main thing I'm thinking about is robustness and lack of maintenance. One advantage of RTGs is that you could distribute power wherever it's needed. RTGs are essentially maintenance free (decades) over the lifetime of the fuel.
There are suitcase-sized power plants that NASA have proposed, but I have no idea how feasible they are - or what the maintenance requirements are. I've not been able to find any actual papers on the subject, just the usual gushing science press. Safety seems to be OK, but these are incredibly complicated systems requiring liquid metal cooling (for a start).
Yea, each A4W reactor on a Nimitz class aircraft carrier can produce on the order of 100MW electricity, and the fuel rods last about 25 years. So if you can scale those down sufficiently (maybe use in situ materials for shielding?), getting to the GW range doesn't seem as far off as I had initially suspected.
https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...