Background knowledge Nuclear power Nuclear power can come from the fission of uranium plutonium or thorium or the fusion of hydrogen into helium. Today it is almost all uranium. The fission of an atom of uranium produces 10 million times the energy produced by the combustion of an atom of carbon from coal. By 1993, there'd been 109 licensed power reactors in the U.S. and about 400 in the world They generate about 20 percent of the U.S. electricity.Background knowledge ◼ Nuclear Power ◼ Nuclear power can come from the fission of uranium, plutonium or thorium or the fusion of hydrogen into helium. Today it is almost all uranium. The fission of an atom of uranium produces 10 million times the energy produced by the combustion of an atom of carbon from coal. By 1993, there‘d been 109 licensed power reactors in the U.S. and about 400 in the world. They generate about 20 percent of the U.S. electricity