The US (and/or China, Russia, and Canada) are bad examples, because most countries are not nearly as large, and most countries want some measure of "ensured by our own hand" electrical-grid independence/fault-tolerance (even though they share a power-grid with their neighbours), just like most countries want a standing border-defence force (even if they participate in a defence alliance.)

So what you'd get in practice, in a nuclear-first world, is O(K log N) power plants: i.e., log(N) plants per country, for each of K≥195 countries.

The world already operates more than 195 nuclear power plants.