How nuclear plants work

Mighty power from tiny atoms

A nuclear power plant is not all that different from coal, oil, or gas fueled plants. The main difference is that at a nuclear power plant, the heat used to make steam is produced by fission.

Fission is the splitting of atoms into smaller parts. Some atoms, themselves tiny, split when they are struck by even smaller particles, called neutrons. Each time this happens more neutrons come out of the split atom and strike other atoms. This process of energy release is called a chain reaction. The plant controls the chain reaction to keep it from releasing too much energy too fast. In this way, the chain reaction can go on for a long time.
Few natural elements have atoms that will split in a chain reaction. Iron, copper, silver and many other common metals will not split, or fission. There are isotopes of iron, copper, etc. that are radioactive. This means that they have an unstable nucleus and they emit radioactivity. However, just being radioactive does not mean that they will fission, or split. But uranium will. So uranium is suitable to fuel a nuclear power plant.

What radioactive means

URANIUM PELLETS: Pellets that look like these have the power of many tons of coal.

Radioactivity means giving off radiation. Radiation is a spontaneous emission of energy from the nuclei of atoms. It is naturally occurring, but it is also a byproduct of the fission process. Uranium is radioactive and when it splits, the atoms that are produced are also rad ioactive. Also, some metals that do not split when struck by a neutron will absorb the neutron and then become unstable or radioactive.

Heat makes it work

Boiling Water Nuclear Power Reactor

As atoms split and collide, they heat up. The plant uses this heat to create steam. The pressure of the expanding steam turns a turbine which is connected to a generator. Click on the drawings below to see animated versions of a pressurized water reactor and boiling water reactor.

Pressurized Water Nuclear Power Reactor

Getting a charge out of it
After the steam is made, a nuclear plant operates much like a fossil fuel plant: the turbine spins a generator. The whirling magnetic field of the generator produces electricity. The electricity then goes through wires strung on tall towers you might see along a highway to an electrical substation in your neighborhood where the power is regulated to the proper strength. Then it goes to homes and businesses providing electricity to power lights, heaters, air conditioners, computers and more.

Safety first
The Nuclear Regulatory Commission (NRC) makes sure nuclear power plants in the United States protect public health and safety and the environment. The NRC licenses the use of nuclear material and inspects users to make sure they follow the rules for safety.
Since radioactive materials are potentially harmful, nuclear power plants have many safety systems to protect workers, the public and the environment. These safety systems include shutting the reactor down quickly and stopping the fission process, systems to cool the reactor down and carry heat away from it and barriers to contain any radioactivity and prevent it from escaping into the environment.

Clean air

One of the greatest benefits of nuclear plants is that they produce emissions-free energy. The big towers many people associate with nuclear plants are actually for cooling water used to make steam. (Some other kinds of plants have these towers, too.) The towers spread the water out so as much air as possible can reach it and cool it down. Most water is then recycled into the plant. The puffs you see coming out of a cooling tower are just clouds of water vapor.

Learn more
It’s fun to study about nuclear energy. To learn more about this fascinating science, please visit the Nuclear Energy Institute and the Nuclear Regulatory Commission’s Web sites. Some of the material on this page is from these organizations — we thank them for their help. Also take a look at Learning Power, the Southern Company energy education Web site.

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