U.S. nuclear plants NEI website NEI website show 99 nuclear reactors the 20% contribution show US Nuclear Power Plants (Nuclear Energy Institute) 20% of the electricity generated that nuclear made 19% of U.S. electricity 19.5 percent kilowatt hours produced by the US nuclear fleet in 2015 Nuclear Energy Institute (NEI) Nuclear Energy Institute only 19.7% of U.S. electricity production as of 2016 US Nuclear Power Plants that nuclear made 19% of U.S. electricity fleet of 99 reactors nuclear power. 99 nuclear reactors operating in the United States four are currently under construction US Nuclear Power Plants (Nuclear Energy Institute) Nuclear Energy Institute Nuclear Energy Institute