Desperate, much?

Am I living in an alternate universe? US, UK, Russia, France have been putting nuke plants in submarines for half a century, most of these countries have done the same with surface ships, be it carriers or ice-breakers, Russia has built nuke plants on barges to provide power for remote areas; heck, the US even ran a nuke plant on a plane, and I am the one being desperate?

Yes. Yes, you are.

In none of those cases have economic considerations been dispositive, or even of much interest.

That's moving goalposts; of course small-scale production is going to cost an arm and a leg. The original post said it was impossible, not expensive.

In an open, uncoerced market, anything too expensive does not happen. People opt for cheaper alternatives, or for more value for the same money. Or, somewhere in between.

Of course, and naturally, first-of-a-kind are bloody expensive. Maybe there's a way to make small nuke plants economical, maybe there's not, I dont' know. But it's definitely not ‶impossible″ to humankind.

They are all extra-super-expensive. Experience is that second and third of a design cost even more than the first one.