Nuclear power plants provide about 17 percent of the world's electricity.
Some countries depend more on nuclear power for electricity than others.
In France, for instance, about 75 percent of the electricity is generated from nuclear power, according to the International Atomic Energy Agency. In the United States, nuclear power supplies about 15 percent of the electricity overall, but some states get more power from nuclear plants than others. There are more than 400 nuclear power plants around the world, with more than 100 in the United States. In this edition of How Stuff Works , we will examine how a nuclear reactor and a plant work. We'll explain nuclear fission and give you a view inside a nuclear reactor.