In the AEO2011 Reference case, nuclear power capacity increases from 101.0 gigawatts in 2009 to 110.5 gigawatts in 2035 (Figure 82), including 3.8 gigawatts of expansion at existing plants and 6.3 gigawatts of new capacity. The new capacity includes completion of a second unit at the Watts Bar site, where construction on a partially completed plant has resumed. Increases in the estimated costs for new nuclear plants make new investments in nuclear power uncertain. Four new nuclear power plants are completed in the Reference case, all of which are brought on line by 2020 to take advantage of Federal financial incentives. High construction costs for nuclear plants, especially relative to natural-gas-fired plants, make other options for new nuclear capacity uneconomical even in the alternative electricity demand and fuel price cases. In the GHG Price Economywide case, which attaches a price to reductions in carbon dioxide, total nuclear capacity additions from 2010 to 2035 increase to 29 gigawatts as a consequence of the higher costs for operating fossil-fueled capacity.