nuclear power

I am reading on Scientific American (http://lescienze.espresso.repubblica.it/articolo/Il_grande_piano_solare/1324927) that a project stresses that USA could produce 50% of power and 90% of electric power by solar in 2050. Nowadays in USA nuclear plant are almost completely dismantled; should they turn to nuclear power, they could, even with huge investments, cover perhaps 20% of electric power by 2050 (not considering the risks and the pollutions and the wastes).