Here’s How a Nuclear Reactor Actually Works
Our largest source of clean energy uses a process you can’t see: fission. At nuclear power plants across the country, highly trained workers monitor an ongoing chain reaction that generates heat and steam, which is then converted to electricity using a turbine.
Here are the three steps that reactors use to make clean electricity.
Nuclear plants harness the incredible power of nuclear fission to generate heat and energy, which ultimately becomes electricity. Fission occurs when a neutron hits a larger atom and splits the atom into two smaller atoms.
When a reactor starts, the uranium atoms in the reactor core split, releasing neutrons and heat, and kick off an ongoing chain reaction that generates more neutrons and heat.
While other power plants burn fuel to create steam and turn the turbine, nuclear power plants are unique. There is no fuel being burned to generate electricity – which means they do not emit carbon dioxide or greenhouse gases in the process.
The only byproducts are energy and heat. There are no additional particles released. In contrast, coal and gas plants release contaminants, including sulfur dioxide, nitrogen oxides and carbon dioxide, during combustion, as they generate electricity.
How do we get from fission to electricity? Water is in large part the answer.
The reactor core (where uranium atoms are splitting) is immersed in water. As the chain reaction happens, the heat generated is used to create steam.
There are two types of nuclear reactors in the United States—both use steam to power a generator, but the difference is how they create it.
Of the nation’s 96 reactors, 32 are boiling water reactors, while 64 are pressurized water reactors. Boiling water reactors heat the water surrounding the nuclear fuel directly into steam in the reactor vessel, while pressurized water reactors heat the water surrounding the nuclear fuel but keep the water under pressure to prevent it from boiling.
In a pressurized water reactor, pumps move the hot water from the reactor vessel to a steam generator. There, the water pumped from the reactor heats a second, separate supply of water, which boils to make steam.
In both types of reactors, the steam spins the turbine, which drives the generator that produces electricity. This mechanism is the same as the turbine used to generate wind power; the only difference is that steam causes the nuclear reactor’s turbine to spin, not wind.
After the steam is used, it gets condensed to water so it can be recycled and reused.
Have you ever wondered about the large towers you’ve seen while driving by a nuclear plant? Though it may look like they are emitting smoke, it’s actually just water vapor. The cooling towers are part of the cooling water system used to condense steam from the turbine back into water. Not all nuclear plants use cooling towers, in some cases they use a large body of water or river to condense the steam back to water. Cooling towers are not unique to nuclear power plants; other generating facilities such as coal plants and other industrial facilities may also use cooling towers.
How do you sum all this up? Nuclear reactors split atoms to boil water into steam, which turns a turbine that generates electricity. No burning of fossil fuels, no combustion byproducts. That’s what makes it the clean, reliable energy source we need.