PyroDesu

The CANDU reactor (second design referred to) can even burn the various actinides. And even some unreprocessed fuel from other types of reactors, as I recall.

I'll certainly try this one as soon as I get back to my KSP-capable computer, it looks fun (and I love stationbuilding). Might make SirJoab define a new rule or two, though - I plan on using the most Kerbal of launch systems if the correct mod is up-to-date.

If my computer could even run unmodded KSP properly, I would download this mod right now. The Orion is one of the most insane rocket ideas (that could actually work) that I know of (thanks to your site, Nyrath), and having it for use in KSP is awesome.