Nuclear Power

Nuclear power is a way of making electricity by splitting atoms. It uses the energy stored deep inside the tiny center of an atom, called the nucleus. About 10 percent of the world's electricity comes from nuclear power plants. France gets most of its electricity this way, and the United States runs about 90 nuclear plants.

The science behind nuclear power is called fission. Fission means splitting. Inside a nuclear plant, scientists shoot tiny particles at atoms of a heavy metal called uranium. When a uranium atom is hit, it splits into smaller pieces. This split releases a huge burst of heat. It also releases more particles, which hit other uranium atoms and split them too. The chain keeps going by itself.

A nuclear plant uses that heat to boil water. The boiling water makes steam, and the steam spins giant machines called turbines. The spinning turbines make electricity. So even though the science is unusual, the last step is the same as in many other power plants.

The reaction has to be controlled very carefully. Engineers slide special rods into the reactor to slow it down or speed it up. Thick walls of steel and concrete keep the radiation inside. Radiation is a kind of invisible energy that can hurt living things if too much of it escapes.

Nuclear power has big advantages. A small amount of fuel makes a huge amount of electricity. The plants do not burn anything, so they do not put carbon dioxide into the air. That makes them helpful in fighting climate change.

But nuclear power also has serious problems. The used fuel stays dangerously radioactive for thousands of years, and nobody has agreed on the best place to store it. Accidents are rare, but they can be terrible. In 1986, a reactor in Chernobyl, Ukraine, exploded and forced more than 100,000 people to leave their homes forever. In 2011, a giant tsunami in Japan damaged the Fukushima plant and caused another big leak.

People still argue about whether the world should build more nuclear plants. Some scientists say we need them to replace coal and gas quickly. Others say wind and solar power are safer choices. Both sides agree the question matters a lot.

Scientists are also studying a different kind of nuclear power called fusion. Fusion joins atoms together instead of splitting them. It is the same reaction that powers the Sun, and it would make almost no dangerous waste. Nobody has built a fusion plant yet, but researchers around the world are trying.