The primary reason why nuclear is in trouble is cheap, plentiful natural gas.
Nuclear plants don’t ramp up or down with demand. They’re steady workhorses, running when it’s economical as well as when it isn’t and providing a backbone to the electric grid. In the U.S., about 20 percent of electricity comes from nuclear power.
But the price of electricity is determined by a regional wholesale market each day. Power plants offer to produce power at various prices and their offers are accepted from the lowest to higher until the demand for electricity is met.
The price offered by the last plant in that line becomes the price for all plants called on to produce power.
More often than not, the price is set by a plant that runs on natural gas. As the price of that fuel has fallen over the past several years, the price of electricity on the grid has fallen as well.
That dynamic, along with regulatory costs and lower electricity demand overall, has hurt not only nuclear plants but coal plants as well. (Power Source, 3/6/2017)