Earlier quoted context omitted.
the notion that you can have a power plant which requires outside power in order to not melt-down is -- frankly -- retarded You're right that this is an additional risk factor, which would be eliminated in a design that required only passive cooling after shutdown (and newer designs have this feature). But "retarded" is too strong. Just having the backup generators not come on for a short time period isn't enough; th…
I agree that average over the kilowatt-hours nuclear might be safer than coal. But the problem is that the risk is HIGHLY concentrated. I can self-insure my computers because if one ever fails I have the cash to handle it. It's not a financial crisis. I don't self insure my car (for collision/comprehensive) because it's too big of an expense for me to absorb at any one time without severe hardship. Nuclear reactors (…
But loss of criticality isn't sufficient for the reactor to be "safe". Even with the reactor no longer critical, there are still a lot of radioactive fission products left. The way to prevent them from escaping is secondary containment, which Chernobyl did not have, as I said (Fukushima, and indeed every other reactor ever built that wasn't built by the Soviet Union, has secondary containment).
Of course, as Fukushima illustrated, secondary containment is not the only necessary feature for safety. You also need decay heat cooling. The key advantage of a design like LFTR, as compared to a design like Fukushima, is passive decay heat cooling; simple thermodynamics is sufficient to keep the fission products contained and cooled after shutdown. That's why such reactors don't, in your words, "require power to stay safe, even if they're not generating power". However, LFTR is not the only possible design with passive decay heat cooling; there are ordinary pressurized water reactor designs that have passive decay heat cooling (by designing the piping circuits and placing the heat exchangers and core to take advantage of natural convection). Fukushima was not such a design, but they do exist (although AFAIK they didn't when Fukushima was built).
Nuclear reactors are one of the few pieces of infrastructure that can't simply be abandoned if something bad happens, or else the problem gets worse and worse and worse.
This is true, but it's just as true of passively cooled designs like LFTR. The problem here is what to do with the highly radioactive fission products. The way every nuclear-using country except the US deals with this is reprocessing: you take the spent fuel, separate out what's still fissionable (which is a pretty large fraction of it with most current designs), and put what remains through a special reactor that converts the fission products to either much longer-lived (and hence much less radioactive) or stable isotopes. Problem solved. France and Japan have been doing this at scale for several decades now. The only reason the US doesn't is politics.