> this issue is that it got caught in a death spiral due to Chernobyl.
Nuclear (fission) power's unprofitability predates Chernobyl to the very first reactors and continuing up to this day. The Shippingport Atomic Power Station was the first commercial reactor to come online, and it was a small reactor, cost $78M to construct in 1958. Decommissioning and cleanup 30 years later cost about $100M. Considering the plant and the resulting mess were small, I really don't think it broke even, but I can't find any economic analysis that includes all the things.
A study in 2019 found that nuclear power has not been profitable anywhere in the world.[1] The study also found nuclear power has never been financially viable, that most plants have been built while heavily subsidised by governments, often motivated by military purposes, and that nuclear power is not a good approach to tackling climate change. It found, after reviewing trends in nuclear power plant construction since 1951, that the average 1,000MW nuclear power plant would incur an average economic loss of about $8B.
And R&D in fission is complete. We know pretty much all there is to know regarding it, and reducing cost simply is not viable through more investment in R&D. We've been working on this in earnest since the late 1940's, so it's no surprise we have figured everything out other than how to do it cheaply enough to achieve economic viability. There are some nuclear power applications where economic viability don't matter, such as nuclear subs and aircraft carriers, and I expect we won't stop building those, but commercial nuclear power just can't work because of the money, and nothing else is needed to say "no," and if it was economically viable, no other objections, such as environmental, would stop it.
[1] https://www.mr-sustainability.com/stories/2020/nuclear-power...