> As far as I know though, Chernobyl and Fukushima had completely different reasons and don't really clump together apart from "both were meltdowns"

A glass-half-empty view of that would be that there isn't a single reason which could be fixed to avoid all future issues. Fukushima AFAIK didn't have the design and operational mistakes which led to the Chernobyl incident, but that wasn't enough to prevent it from having its own incident. Which other causes we might be missing which could lead to new severe incidents in other nuclear power plants?

(And, by the way, the bad part IMO was not "both were meltdowns", but "both were explosions"; if it were just the meltdown, it would stay confined within the power plant, while the explosions are what spread the damage. Yes, they weren't nuclear explosions, but even a non-nuclear explosion in a nuclear power plant is bad.)

But nuclear power starts to look even better when you look up the death tolls and realize that as long as you are halfway competent (i.e. not Chernobyl) even the worst disasters have led to vanishingly few deaths. What is more dangerous is the irrational fear of nuclear power that led to the dangerous evacuation of Fukushima.

We have modern designs that Litterally can not melt down. No meltdown means no explosion.

Maybe. I'm trusting one comment on internet.

I'm pretty sure the Chernobyl engineers also said "this is impossible", "this is very safe design that can not fail". Only in hindsight did the failures appear.

For Fukushima. Sure, once in a lifetime earthquake. It's always something, and at some point walls can't go any higher. Seems like backup pumps should have been on higher ground. But to think nobody will do something similarly silly again, is being pretty trusting.

The difference is in Chernobyl there were mechanical safety systems to stop a meltdown. current designs are such that physics prevents it from being able to melt down. While its possible to improperly maintain safety systems causing them to fail, physics doesn't need maintenance.

Do you have link? I am curious what this design is.

If I just randomly search, it is just hundreds of designs, everyone has a 'theory' on some design that is safe and effective. Hard to filter out the 'crack-pot' from the actual physicists.

Do you have one in-particular.

(edit, also. I ask because Chernobyl was also deemed impossible by 'physics'. Technically it did not melt down first, the reactor didn't 'fail', something else fails, then melt down happens. The risk was never a nuclear explosion, it was release of nuclear material and radiation)

pebble bed reactors.

to quote wikipedia which expalins it better than i can;

"When the reactor temperature rises, the atoms in the fuel move rapidly, causing Doppler broadening. The fuel then experiences a wider range of neutron speeds. Uranium-238, which forms the bulk of the uranium, is much more likely to absorb fast or epithermal neutrons at higher temperatures. This reduces the number of neutrons available to cause fission, and reduces power. Doppler broadening therefore creates a negative feedback: as fuel temperature increases, reactor power decreases. All reactors have reactivity feedback mechanisms. The pebble-bed reactor is designed so that this effect is relatively strong, inherent to the design, and does not depend on moving parts. If the rate of fission increases, temperature increase and Doppler broadening reduces the rate of fission. This negative feedback creates passive control of the reaction process."

Thank You Yes, guess any built in Negative Feedback would be better than defaulting Positive Feedback.

Guess someone could still do some bad design to cause some other type of rupture that would expel radioactive material, but much less possible.

A rupture is unlikely as most pebble bed designs use helium as the coolent. It being a noble gas it won't react chemically, and unlike water cooled designs it doesn't undergo phase change (liquidgas) so no massive pressure build up. And as there is no oxygen fire is unlikely.

So 2 mistakes in the last 50 years, each wiping out a radius of 25km from being habitable for 1000 years. I won’t trust people for not making more mistakes.

Its not likely to be a thousand years before its habitatable again. Long lived isotopes are safer as they are less radioactive and less energetic. And short lived isotopes while dangerous are short lived. Its the medium lived that are a problem 70-150 years that are the biggest problem. Secondly we dont have to wait for it to all to be gone just down to a safe background level

There is a common cause.

Humans.

You mention both Cost Savings and Design Mistakes. Those are common, and will occur in future projects.

Don't think totalitarian Gov has any monopoly on hiding design problems. Every company does it.

Those are both things, drives, that the US has shown to be incapable of administering. All industry is rife with cost cutting. And "safety" is very much cut in the name of profits. It happens today, just not 'obvious'. We don't hear about it until there is a meltdown.

I do hope that new designs are better. But I am absolutely not confident that humans have learned anything and wont subvert any improved designs again for cost savings.

> Chernobyl was entirely a product of design compromises due to cost savings, combined by a totalitarian system suppressing the known impact of those design decisions.

This sounds exactly like what could happen when a private for-profit company would exploit nuclear, which is already happening