Probably a stupid car question...

[kandrathe]

I agree with Lissa on this point. One can say "choose a better nuclear reaction", but nature really doesn't offer one. You can say "choose better shielding materials" but even the best possible still take pretty good thicknesses to work.

The Catch-22 is that if you use low energy reactions, you don't need as much shielding but then the pile has to be much larger to get a sustained reaction. If you use high energy reactions, you can make the pile smaller, but you then need more shielding. Optimizing just for weight, you still end up with something more suitable for railroad engines than cars or trucks. And that optimization involves using some nasty materials and insufficient containment for purely mechanical accidents.

There has been recent work showing that fission product of 235U induced by thermal neutrons show points where fission results in almost stable isotopes. What we do now is a mostly uncontrolled reaction where we need to deal with a potpourri of fractured unstable byproducts, where most of the dangerous stuff (highly energetic) decays within days to weeks. The challenge is to create a fission reactor that results in controlled more stable "waste", and you will greatly reduce the need for shielding.

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.

OK, here we're back to naquadah generators (i.e., science fiction). Do you have anything beyond imagination to indicate that the strong force can be re-coupled to the electro-weak in anything other than the conditions immediately after the Big Bang? I suspect that if undoing of the symmetry breaking is possible at all, the energy available will be many orders of magnitude smaller than the energy required. I suspect that that technology will be contemporary with the space warping FTL drive.

If I outlined how to do that, I'd be in contention for the Nobel at least. It's one thing to learn enough to theorize the feasibility, another to work out the theory, and quite another to put it into practical reality. Look what has been achieved in your brief lifespan? You are almost older than the entire field of quantum physics.

From Wikipedia... "As of 2011 the quest for unifying the fundamental forces through quantum mechanics is still ongoing. Quantum electrodynamics (or "quantum electromagnetism"), which is currently (in the perturbative regime at least) the most accurately tested physical theory,[35] has been successfully merged with the weak nuclear force into the electroweak force and work is currently being done to merge the electroweak and strong force into the electrostrong force. Current predictions state that at around 10^14 GeV the three aforementioned forces are fused into a single unified field,[36] Beyond this "grand unification," it is speculated that it may be possible to merge gravity with the other three gauge symmetries, expected to occur at roughly 10^19 GeV. However — and while special relativity is parsimoniously incorporated into quantum electrodynamics — the expanded general relativity, currently the best theory describing the gravitation force, has not been fully incorporated into quantum theory."