> I am a nuclear expert who got into nuclear to help fight climate change.
I think that is very noble. I am thinking of eventually moving my career to solar or wind for the same motivations.
Chernobyl was partially contained, it could have gone far, far worse. IIRC only 1 of 4 reactors exploded? I suppose hypotheticals are not extremely useful, but what is the hypothetical upper bound on the most catastrophic nuclear scenario?
There are ~equally unlikely life-ending upper bounds of all energy sources. For example, you could have world-ending wars and famines from solar and wind if a superlarge volcano largely blocks out the sun for a few years. Or they could lead to world-ending land wars over sunny and windy areas.
Today, in reality, we have clear and present and known dangers like fossil and biofuel that are currently killing millions and also causing climate change. These things make 84% of our primary energy as a world today. Shifting away from these things to the things low on the ourworldindata graphic above (low carbon, low risk) is a net benefit. Worrying about exceedingly unlikely worst cases is not necessarily productive or useful. Considering them is well and good, sure. But IMHO one must dismiss them quickly based on 60 years of operational experience.
In other words, if someone is currently attacking you and you can pepper spray them, it's probably better to do so than to worry about whether or not the pepper will cause the house to combust.
I would phrase your argument as simple as: you estimate the world is much more likely to become uninhabitable if we don't use nuclear.
What's the worst case of not using nuclear? It's the same as the best case of using it. Best case, nuclear would enable us to entirely phase out fossil fuel energy production, reducing the world's CO2 production by 25%, reducing green house emissions to the point that large parts of the planet no longer become uninhabitable.