Whenever I play as Yugoslavia I can't build a nuclear power plant. I played a skirmish on an easy bot and built every building that was available and for some reason it still wouldn't let me build it.
That's because Yugoslavia does not get access to the Nuclear Reactor. They get the Reactor Overload upgrade for Tesla Reactors instead.
You can look at unit availability on the website: http://omegabolt.cnc...tion/s_tech.php