[bzbarsky]

You can go to Three Mile Island just fine as long as you don't go inside the Unit 2 containment vessel itself. The meltdown was fully contained inside said containment vessel. Unit 2 has since had its core removed from the site entirely and has had its electrical generator moved to another reactor (in North Carolina), so it's not like people haven't been going in it either. Unit 1 (the other reactor right next to the one that had a meltdown) has remained a fully operational power station and is used as such today; people go there all the time.

Chernobyl and Fukushima I will grant (especially Chernobyl!) but Three Mile Island has a no-go zone that's far smaller than most people think. And it's only sort of no-go at that.

> which could wipe out our grid, leading to nuclear leaks worldwide

Sorry, but citation needed for the causal mechanism via which the grid going down would lead to "nuclear leaks".

[obpacheco]

I admit a little bit of that is pessimism from what happened at Fukushima from when the plant lost power to run the cooling pumps. from Scientific American

> Pushing water past the core means pumps that are generally run by electricity. What happens when a reactor gets disconnected from the grid? There are emergency diesel generators. You also have a battery system to keep instruments running, but that can also provide power to safety systems [which prevent a meltdown by cooling the reactor core]. It's all meant to provide defense in depth. First you rely on the grid. If the grid is no longer available, you use diesel generators. If there is an issue with the diesels, you have a battery backup. And the batteries usually last long enough for you to get the diesels going. [1]

All I'm saying is that we have a very short term understanding of cosmic events and extreme space weather events [2] and maybe a good percentage of nuclear power plants could withstain these types of events, but I don't see it as a viable long term option.

[1] https://www.scientificamerican.com/article/how-to-cool-a-nuc...

[2]https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/201...

[bzbarsky]

Right, at Fukushima it wasn't just loss of power that was the problem, it was the loss of all the backup power sources too, _combined_ with a design that required power to operate the cooling system.

I agree that this is something we should be keeping in mind as we build new reactors. And people have in fact kept it in mind. Modern reactor designs use passive cooling systems that don't need power to operate properly.

The single best thing we could do for nuclear safety, including from extreme space weather effects, is replace decades-old plants with modern ones. Unfortunately, people tend to react to that with "we shouldn't build any new nuclear plants, even if we're replacing old and less safe ones".

Just to put this in perspective, the first ever commercial nuclear plant was opened in 1956. Fukushima construction began in 1967, finished in 1971, 40 years before the meltdown. We've learned a good bit about safety in reactor design in the 50+ years that have passed since Fukushima was designed...