Ok... a longshot (and it's not particularly detailed):
https://steamcommunity.com/sharedfiles/filedetails/?id=11275...Rimatomics is a mod for the strategy/base builder game Rimworld, adding nuclear reactors and real-world/fictional nuclear powered weapons. You can build your own reactor designs by connecting cores to heating and cooling lines, the heating line to a turbine and then a turbine into a power generator. The challenge comes less from meticulously managing the reactor, and more from protecting it during raids and disruptive events. It's not really a "study sim" so much as it's a satisfyingly complete nuclear reactor conversion mod, but I've had a few reactor-focused playthroughs that are very satisfying.
I've played probably a hundred hours with this mod on Linux and it's quite good. Your enjoyment will probably depend on whether the base game of Rimworld appeals to you though.