Probably a stupid car question...

[Lissa]

Yeah, their present tendency to go unstable and wipe out a whole city leaves a little to be desired.

And, the glass is still half full.

But... it is kind of true that we have the technology to create millions of small scale power reactors that would be emissions free, however, the powers that be don't want to allow such devastating power into the hands of consumers, even if it were affordable. If they were designed to be modular and portable, they would survive multiple vehicle shells before running out of power.

The problem isn't so much minaturizing, it's shielding. To give you an idea, the TRIGA that the University of Arizona had (the decommissioned and pulled it out this year) used 20 feet of water to shield people from the radiation. While in a shutdown state, the radioactivity in the reactor room was at background levels, but when the reactor was powered up, you were still taking about 10 mRem/hr.

So, in order to properly shield a reactor core, you would need a dense material for the gammas (tungsten, lead, uranium - yes, it's a great gamma shielder) and something loaded with hydrogen (water, parafin wax) for the neutrons. This so called minature reactor would actually be about the size of the car itself with the power transformation equipment (turbines, generators, pumps/compressor depending on the cooling fluid for the reactor) in order to properly shield it from the gamma rays and neutrons it was producing.

Miniaturization in a different form. Since not many people are designing mobile reactors, there are not any rapid advances in the technology. Most mobile applications (US navy) can accommodate devoting a large engine room for the comparatively large power required to move an aircraft carrier or a submarine. Scaling it down to 200 to 225 Kilowatts, would require core modifications to augment critical mass. The problems I see are that we currently simply create a fissile pile, then ameliorate the consequences with shielding and cooling. Heat is transformed into power the old fashioned way. It would be better to find fissile materials with fewer negative effects, and create a mechanism for better conversion and control of the power output.

Ford Nucleon

Incorrect, the TRIGA was 100 kW and required that 20 feet of water for shielding while powered. Radiation has to be attenuated which requires material between the radiation source and the object(s) being shielded. There is a known amount of distance of certain materials required to cut down on the radiation. To cut the radiation for a gamma source in half requires 40 feet of air, with other materials it can be less than an inch to a foot (believe it or not, in the event of a nuclear detonation, 6 feet of earth will cut the radiation to near 0 levels if you're not in the pressure/temperature killzone).

To give you an idea of what needs to be done, the first landers on the moon used the SNAP (Space Nuclear Auxilary Power) reactors that made their power by interactions from alpha particles against a film. One of the things most people don't know, and what Neil Armstrong did first thing after exiting the lunar lander, was to take a Plutonium rod from one of the lander legs (I've been able to identify where it was on the lander after seeing a lander mock-up at the Smithsonian's Air and Space museum) and place it into the SNAP to begin producing power. The reason the rod was placed on the leg and not in the compartment with the astronauts was to protect them using the lander's shielding from the gamma rays that are emitted from Plutonium (yes, it's primarly an alpha emitter, but when emitting alphas, there is a likelihood of releasing gamma rays as well to reduce excess energy in the decay process). 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.