For the first time in 30 years, the United States has licensed the construction of new nuclear reactors. Given a price tag of $10 billion per plant, the comparatively cheap cost of alternatives such as natural gas, and the Fukushima nuclear disaster in Japan, the decision is fraught with controversy. Aside from these new reactors, the country must also decide what to do with its fleet of 104 aging nuclear facilities. Licenses for about 70 of them have been renewed and the others are pending or expected. If any one plant is taken off line, how would that electricity be replaced?