From the developer videos, there will be a new resource called "reputation". I think that, in order to launch a rocket from Kerbin with a nuclear fueled engine or power source, it should require larger than a certain reputation score in order for the public to "trust" you with fissionable materials. Mods that add more nuclear options like KSP Interstellar would impose similar requirements. Each nuclear fueled launch would "cost" reputation as well, or you should get a very limited allocation of it. This would reflect how in real life, NASA has a heck of a time even getting ahold of decaying Plutonium for their RTGs. NASA can only dream of getting enough HEU for a nuclear thermal rocket. I also think that kerbonauts should have a fame stat that will govern how much money you get for completing a manned mission using a particular kerbonaut. The more missions they complete, the more famous they get. Obviously, Jeb would start out with near maxed fame stat. Getting a kerbonaut killed who is famous would cause a bigger reputation hit than getting someone killed who is a nobody. If you crash a vehicle with nuclear materials onboard into Kerbin, it should result in a gigantic loss of reputation. Crashing into land would be worse than crashing into water. The game would need an "iron kerbal" mode for this new system to actually work. In this mode, you would not be permitted to revert or load a quicksave. Of course, when and if they ever add resources, you would be able to mine other planets for things like fissionable materials, and resources gotten this way would not cost you reputation or money.
