nuclear power was widely available

"In the United States, the Price-Anderson Act of 1957 limits the liability of the nuclear power industry in the case of accidents" - That is interesting fact #1 for the day that I did not know.

Though I'm not sure that nuclear power accidents are so endemic and common that the cost of such insurance would in fact be prohibitively expensive. The cost of a disaster the scale of Chernobyl is so catastrophic and high that it may still be. Some actuary would have to run these numbers. Along with the probability of such an event occurring from some other cause. Which would be rather hard to probabilistically calculate given that it's the only major nuclear disaster other than the two atomic bombs that were dropped. Three Mile Island is the only major drain on this insurance pool we've had and it amounts to about only $70 million (with most of that settlement payments and public health funding rather than actual substantiated health damages). We (or rather, "Western" constructed and run nuclear power plants) have had other nuclear incidents prior to Three Mile, as well as a few afterward which were bad for the people involved (usually military or scientists or plant workers), but nothing on a scale like Chernobyl.

For good reason. Try looking up how that happened. It's practically impossible to conceive of happening anywhere else in the world. More or less a "deliberate" accident from a happy string of coincidences involved in the Soviet era and terrible design flaws.

And then check how many people actually died. Considering there was also a big goddamn fire there to deal with, I'm surprised at the death toll as well. Much of it was the firefighters themselves (though there will undoubtedly be some cancer related deaths throughout the area for many years). The biggest consideration, economically speaking as an insurable event, was probably the destruction or abandonment of a nearby town and various equipment used to clean it up (and protect against the still radioactive pile) from radiation levels more so than the actual damages suffered physically.

An accident like that would be no joke. Though as I said, the probabilities of such an event are so astronomical that it is hardly a matter of greater public concern. The most recent examples of nuclear accidents tend to deal with the containment of consumed fuel rods (or their assembly) and waste material and less the with actual generation of power causing an accident in and of itself. The possibility of a radioactive leak or spent fuel rods doing something rather naughty shouldn't be discounted as irrelevant events, but I'm pretty sure the damages to the public are also far less than a probable meltdown of a functioning nuclear power facility and thereby much easier to insure against with private insurance markets. And also to design appropriate countermeasures for either disposal or storage to further lower those insurance costs over time.

Ideally we'd figure out a way to get rid of the waste rather than leave it in barrels for the next 10,000-20,000 years with the assumption that we'll be able to keep people away from it for that long. When one considers what modern archaeologists do with tombs less than half that old and the language or symbolic barriers involved in sustaining such a thing. One assumes, given the patterns of human history and general ignorance about scientific facts, that it could develop into a sort of mythology or curse rather than some sort of genuine understanding of the danger. Which isn't exactly the best way to insure that we don't foster some non-trivial accidents for centuries yet to come.

(I'm never quite sure why Civilization games have had nuclear power plants that are so volatile that they can basically destroy your cities. It seems like the thing they ought to do, based on how nuclear power plants and their industry operate in the real world, is cost a lot of money to maintain and piss people off and maybe kick off some "unhealth" or pollution from the storage of waste material. Rather than kill them off by the millions at even a relatively small rate, much less something approaching the actual meltdown incidence point at infinitesimally smaller rates than are used by the game itself).