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Exploring Energy
Science Texts for Close Reading
Nuclear Energy
How is electricity generated at a nuclear power plant? Well, it is often a lot like how electricity is generated
at a coal power plant, but with one key difference. In both cases, water is heated into steam, which turns
a turbine connected to a generator. The generator converts the mechanical energy of the spinning turbine
into electrical energy that can be transmitted to homes and buildings through transmission lines.
The key difference between a coal power plant and a nuclear power plant is in the fuel they use to heat the
water. In a coal power plant, burning coal supplies the energy to heat the water, which releases carbon
dioxide—a powerful greenhouse gas that is contributing to global warming and climate change—and other
pollutants into the atmosphere. In a nuclear power plant, this energy comes from nuclear fission, or the
splitting of a large atom like uranium into two smaller atoms. Fission happens when a neutron—a neutrally
charged particle—collides with a uranium atom. This collision releases more neutrons, which are free to
collide with more uranium atoms, causing more fission. When this fission chain reaction is carefully con-
trolled in a nuclear reactor, a constant supply of energy is produced. And it doesn’t take much uranium to
produce a lot of energy. A single pellet of uranium less than one inch long can produce the same amount of
energy as a ton of coal1!
Nuclear energy is nearly greenhouse gas-free, meaning that it doesn’t release carbon dioxide into the atmo-
sphere like coal power plants do. However, nuclear energy isn’t without some drawbacks. Nuclear fission
is a type of radioactivity, and large amounts of this kind of radioactivity, or radiation, can be harmful to life.
The uranium used in a nuclear reactor is carefully trapped and contained so that radiation cannot escape,
and nuclear power plants are protected by all sorts of systems that can shut the reactors down quickly if
something were to go wrong, but that hasn’t prevented a few nuclear accidents from happening in the past2.
Environments that are contaminated by high levels of radiation are dangerous to live in or visit.
Over time, the fuel in a nuclear reactor becomes less and less effective, and must be replaced with new fuel
and disposed of. However, this old, or ‘spent’ fuel is still radioactive and can be so for hundreds of thou-
sands of years3, so it needs to be disposed of in a way that won’t harm the environment or people. This
might mean burying it deep underground, but if this isn’t done properly, it could contaminate groundwater
that might come in contact with it.
To learn more about other energy sources and technologies, go to the Exploring Energy homepage.
1 Duke Energy: How Do Nuclear Power Plants Work?
2 Union of Concerned Scientists: A Brief History of Nuclear Accidents
3 United States Nuclear Regulatory Commission: High Level Waste
