What's stopping the expansion of nuclear power is its own high cost, as in this example from David Shaffer of the Minneapolis Star Tribune:
Xcel originally planned to boost the output of the Prairie Island plant by 164 megawatts with upgrades to the reactor in 2014 and 2015, but the utility shelved those plans last October.Not only do you have to build the plant (expensive!), you have to have a plan for what to do with the spent fuel (expensive & dangerous!), get a water source to cool the plant (increasingly uncertain - thanks, climate change!) and the big one, you have to insure the plant (incredibly risky & expensive!). At every step of the way, nuclear power relies heavily on taxpayer support, either directly through subsidies & loan guarantees or indirectly through use of public resources & public assumption of risk.
Electricity demand has not been growing as fast as the company earlier estimated, and cheaper natural gas had become more attractive as an alternative power source, the utility told state regulators.
Given all that, why not just build a natural gas plant, or better yet, a wind farm? That's nuclear's real problem.