The US navy uses nuclear reactors for their aircraft carriers and they don’t seem to have the same problems getting them built and installed that commercial power operators do now. I wonder what makes the difference, I tried googling but couldn’t find a good comparison. Perhaps it is just not commercially viable but works on a military scale budget?
Also those old powerplants were not built with safety in mind. In my country they literally dumped nuclear waste into the sea. Back in the sixties they were cutting corners, something we couldn't do today (I hope).
See for example
https://fluormarinepropulsion.com/
https://www.bechtel.com/services/defense-nuclear-security/us...
https://www.bwxt.com/what-we-do/naval-nuclear-propulsion
Welcome to the military-industrial complex
[1] https://en.wikipedia.org/wiki/Olkiluoto_Nuclear_Power_Plant#...
[2] https://news.ycombinator.com/item?id=13987046