Probably a stupid car question...

[kandrathe]

... So, you have to have shielding of some kind and you have to have a given amount for it to cut down on the radiation.

I think you misunderstood me. I'm not saying that shielding is unnecessary, I'm saying that by choosing better nuclear reactions you can minimize the amount of harmful radiation emitted, and by choosing better shielding materials you can minimize the size and mass of the shielding. Water, concrete, earth, or lead are abundant and cheap, which is why for terrestrial uses or even in large vehicles (like aircraft carriers, or submarines) bulk is still not an issue.

Another point I'm trying to make is that while there have been some advances in making nuclear power smaller and safer, essentially a simple critical mass nuclear reaction is still used to generate steam power. That is a fairly archaic and inefficient way to transfer the power of the strong nuclear force into motive or electrical power. Given more attention and less political antipathy, quantum chromodynamics might have progressed much further than it has. For example, allowing for the direct conversion of the strong force into the electroweak force thereby eliminating waste altogether.