1. The conversion of airplane gas turbines to power generation which have about 1/10 the capital cost of the steam turbines used for coal and nuclear plants. (People still quote the cost of coal as if it was a benchmark but it has been uncompetitive since 1980. So much in energy research is like a stopped clock.)
2. A wrong model for what causes nuclear accidents (e.g. the pressure vessel doesn't burst, instead the power goes out like it did at Fukushima.) Existing plants and new designs had to be retrofit -- U.S. power plants went through post-TMI and post-911 upgrades, but Japan did nothing.
3. Racism and islamophobia. When Pakistan got the bomb the fear of proliferation exploded, putting an end to research in new nuclear reactors (which could have a gas-turbine based cost structure) and sustainable nuclear fuel cycles. (e.g. it's possible to not just use Plutonium as a fuel, but even destroy the most pernicious fission products.)
Fossil fuels are too cheap and approval times for new fossil fuel power stations are surprisingly still much faster than for nuclear. Even though the health impact from the latter has historically been orders of magnitudes (at least 1000x) higher.
You are getting some truly bizarre responses. The real answer is that the same crowd of people obsessed with climate change today were against nuclear power yesterday.
The generation that had a great fear of nuclear bombs due to duck and cover exercises in schools when they were kids started coming into political power (the boomers) and have been in power ever since. Most people don't really separate the idea of a mushroom cloud going up into the sky and a nuclear reactor meltdown in their head. The nuclear power industry should have taken a clue from all of the other industries that use nuclear/radioactive tech and removed the word nuclear from the technology description. Maybe call it isotopic power?
Hopefully younger generations, that seem to be completely unaware that we still live 15 minutes to nuclear armageddon, won't have such a visceral negative view of it and see it as a viable zero carbon energy source.
I long thought that the simultaneous release of "The China Syndrome" and TMI led to public fear of nuclear power (TMI happened two weeks after the movie debuted!). But apparently people have studied this and these disasters really didn't have a major effect -- public sentiment generally stayed the same around the time of the accidents[1]
The passage of PURPA in 1978 had a bigger effect. Suddenly utilities were opened to competition. Combined with a slowdown in growth of electric power demand and the window closed on new nuclear.
I thought it was well known: Building nuclear power stations has been extremely expensive and time-consuming.
Why would anyone invest in that? The answer is climate change, but conservatives in the US have opposed any action on that issue, so there hasn't been political will.
