I disagree that its not the economic choice. I think everybody would agree that for 50 years before lets say the year 2000 is was overwhelmingly the only economic choice for green energy (outside to hydro limited by geography).
After 1990 specially 2000 lots of governments around the world started to massively subsidize solar and wind. While often at the same time having policies punishing nuclear in various ways.
The uneconomical solar and wind became economic because of massive government orders and investment. Even the US often simply set targets for solar and wind that utility providers had to reach. Even nuclear nations like France did so.
So why did wind and solar turn economical, massive investment around the world in making it so. Had Germany, France and the rest of the EU simply gone all in on even a Gen3+ reactor design, and had order 200 of them since 1990, it would also be very economical. History of nuclear shows that if you build the same plant in large numbers, they can be built and finished far faster and cheaper.
And that is even before we consider the huge reduction in capital cost if you go from a PWR design to a GenIV design. Just in terms of the scale of the project, there is a huge difference. Sadly by the time that technology was getting ready for serious commercialization, nuclear was basically seen as legacy and almost all government stopped most research and stop investing in it.
Imagine if nuclear in the 80s had the support wind/solar did in the last decade. If every utility in the US simply sad 'you need X% nuclear by Y date'. And in Europe at the same time as France was building its reactors, Germany, Nordics, Switzerland, Austria, Italy, Britain had also built reactors at the same time.
During the Kyoto protocol talks, France already had a mostly green grid because of nuclear. But somehow essentially nobody copied this success story because it simply wasn't politically viable in most places. It took decade plus after Kyoto before wind/solar were commercially viable but really only if you don't consider intermittency a problem and the market doesn't give you a penalty for it (it usually didn't because before wind/solar that just wasn't an issue). Yet despite solar and wind not being economical, massive investment in it happened and eventually it was made economical thanks to economics of scale.
I would claim if all the investment that was made in wind/solar since 1992 had been made in nuclear, we would produce more green energy now and the cost curve would be driven even lower, and baseload power would be solved as intermittency is simply not a thing. We would not need to redesign grids because nuclear plants would map nicely onto the current grid, if you just replace coal with nuclear.
So, its all about economics of scale, that makes it energy production cheap. Putting up huge wind mills is cheap because there are lots of trained people to do it, the factories can produce large volumes. The largest wind mills now are by themselves large then a whole GenIV plant would be. And produce like 95% less energy and not even consistently.
> I always considered fission tech to be used for the following reasons, and none of them are economic.
You missed that it is green and no CO2. That was not a reason anybody cared about before 2000 but since then it was part of the rational in some countries.
I would like to hear why you think fission can't be economic in principle. Maybe you can make the argument that Gen3 reactors can't be economical but based on first principles, fission itself can be economical if you had economics of scale seems a stretch.