This is projection. The irrationality is thinking that fusion is something desirable. I suspect this follows from exposure to fusion reactors as a trope in SF stories. From a hard nosed engineering point of view fusion is just terrible.
There are all sorts of approaches to fusion, and things such as type 2 superconductors were undiscovered 30 ago and uneconomic/unpractical 10 years ago. Timing control systems for magnetised target fusion were impossible but now are doable. Our understanding of plasma has been advancing a lot, simulations are good now, we can control plasmas much better. Chirped pulsed laser amplification is a thing now and really good at making high amplitude pulsed lasers for inertial approaches...
I could go on and on. This isn't the 90s anymore, and our technology is still rapidly advancing. What happens if we find more efficient/cheap/high power density thermocouples, or find a direct energy electrostatic power capture method?
Fusion's economic realities today may be overcome soon, we really do not know what we can do in even 20 years from now. The fundamental truth is that there is vast amounts of energy available in hydrogen, and all it takes is 100MK to ignite it.
And then you have the problem of having to stick sophisticated stuff in the hot zone where hands-on maintenance is impossible (compared to a fission reactor, where just the fuel and relatively simple hardware is in that zone.)
It's not clear why one should expect fusion to have good experience effects. Fission didn't, and the non-nuclear parts of fusion power plants will be mature technologies.
If reactors were ten times cheaper but no safer, we'd be building them like hotcakes.
The western world has made development of new fission plants practically impossible. Requiring 100s of millions in development before you might get a hint if the government would actually allow you to build a plant.
Thankfully this has finally started to change. Mostly in Canada and that's where we will likely see next generation fission first.
What has also prevented changes from happening is that nuclear scales down poorly, so the cost of iterating designs is so large. Making a new kind of PV cell or module, or wind turbine, is comparatively much cheaper, because these are individually much smaller and cheaper. The replicated nature of these sources is an advantage in so many ways.
No it isn't. If you have a regulatory structure that makes progress so expensive and counter to the government plan then progress is very hard to make.
Even the regulatory agency themselves have realized this and are changing their structures.
> What has also prevented changes from happening is that nuclear scales down poorly, so the cost of iterating designs is so large.
US regulation allows nothing between fully commercial and university research making any time of prototyping impossible.
Its in fact very possible to make smaller reactors that can teach you a lot and are not absurdly expensive and still useful. That data then could be used for to further inform regulatory agencies.
> The replicated nature of these sources is an advantage in so many ways.
Yes but even if it doesn't scale down well in terms of engineering you can still do factory construction of reactors. If we can mass produce plans, rocket engines, rockets and cars then the same could be done with reactors.
The reality is the government selected one winner and made deploying anything else practically impossible. The change in regulatory agencies has basically made progress impossible beyond marginal improvements.
The engineering undesirability of DT fusion has been known for decades. All the recent excitement doesn't address any of the known showstoppers.