As America’s energy demands grow exponentially, the country won’t be able to keep up without more nuclear power. For decades, the climate-friendly industry has been held back by overly burdensome regulations, but that’s beginning to change. In the 1960s, plants took about four years to build, and they cost, in today’s dollars, about $1,500 per kilowatt of electricity generated. Now the idea of building a reactor in less than a decade is unheard of, and the cost of construction is six times greater. The Energy Department took steps this month to exempt certain advanced reactors ...