The trick is, as always, to make a sealed system and scare people into not messing with it.
Having a nuclear reactor in every house would be insane. Even if they don't leak radiation during their lifespan in normal operation. You can scare most people out of opening them. But can you scare every single person out of doing so? Considering some will be mentally unstable too, or outright psychopathic.
The most dangerous thing a mad person can do right now is blow up their house with natural gas. Which is pretty bad, it can damage houses in the nearby area. It absolutely pales in comparison to creating a mini meltdown or even nuclear pollution however. One alpha-emitting dust particle inhaled into the lungs is enough to kill over time.
And this is not a fantasy. It's happened in real life. Consider the Goiania incident for example and it's not the only one.
I'd bet there's a reactor design that's tamper-proof enough to be less lethal than vending machines.
That just leaves very determined, educated terrorists trying to harvest the fuel for radiotoxins or a dirty bomb. There are probably less convoluted ways to cause mass death and destruction than that, but "radioactive" and "fallout" are certainly more terrifying than "gunman" "bomb" or "poison" even if the actual damage is likely much lower.
> The most dangerous thing a mad person can do right now is blow up their house with natural gas.
Wiki says the Oklahoma City bomb cost USD5000 and was equivalent to 5000 lbs of TNT. I don't have a TNT figure for gas explosions in buildings (even the worst-case intentional one you describe), but it sounds like they're way less powerful than that. https://www.researchgate.net/publication/271492483_Hazard_an...
Don't forget to weigh all this doom and gloom against the massive (green) upsides of distributed power generation!
Really, look at that Goiania incident. 93 grams (3.3 oz, less than half the weight of an average smartphone) of radioactive material found by some scavengers who dragged it around the city.
Result: 4 people dead. 249 contaminated of which many with health issues. More than $100 million in cleanup. It was one of the worst radiological incidents.
Now imagine having this kind of material available in every house...
There'd also be massive proliferation of nuclear waste which may or may not be processed and stored correctly.
Well, except for the ozone. That's getting better, though.
Hydrocarbon refrigerants went out of vogue for performance reasons but were/are still used the world over in certain applications and there's been a recent uptick now that we care more about not destroying the environment. The fuel:air mix you need for fire is narrow enough that ignition is mostly not a problem in practice, it also helps that society have moved away from open flames for a lot of heating and lighting applications.
Google "R600a"
No, it is about knowing where the cutoff point of risk vs reward is. It is about understanding when diminishing returns makes something impractical. Trying to design a nuclear reactor small enough for a house or car, that is also so safe, tamper proof, and unweaponizable that it is ok to just have 10s of millions of them floating around is pointlessly difficult. Building a reactor to go into personal vehicles that crash all the time is ridiculous. It’s the different version of the flying car, when we realized that maybe having everyone moving themselves around in personal vehicles that would plummet out of the sky in the event of mechanical failure instead of just pulling over in the breakdown lane. It is a “that would be cool” idea.
Replacing coal plants with nuclear plants is a far better idea. Building self-contained smaller reactors to provide power on the neighborhood, sub division, or factory complex level is a far better idea. Why would I even want a reactor taking of space in my house when I could just get the same electricity from a more efficient reactor installed in a large concrete shed for my whole block? Why would I want to buy an insanely over engineered nuclear car, when I could just charge up my Battery Electric using my neighborhood reactor off peak electricity? Or I could fill up my hydrogen electric car produced by my neighborhood reactor through electrolysis during times of excess power generation.
This has happened, a lot.
Most of the needless venting comes from automotive systems and that's going to be a non-issue in a few years as OEMs continue to switch over to newer refrigerants that are less polluting.