The Fukushima nuclear reactor accident in March 2011 challenged the public’s perception of nuclear power. However, much of this disillusionment simply stems from a lack of understanding of how a nuclear power plant functions.
Inside a Nuclear Reactor
A nuclear power plant is a lot like most coal or natural gas plants. They all create steam to power the plant. Instead of burning a typical fuel such as natural gas or coal, nuclear power plants use a process called fission to create the steam.
Though there are different models used around the world, American nuclear power reactors are either pressurized or boiling water reactors.
Fission is the process of splitting an atom, which then releases energy in the form of heat. The fissionable material used in nuclear reactors is uranium, which is found naturally all over the world.
Uranium ore, however, is not quite ready to fuel a reactor when it comes out of the ground. The ore contains different forms, or isotopes, of uranium. The isotope used for fission in most reactors is uranium-235, but the predominant isotope found in natural uranium ore is uranium-238. Only around 0.7 percent of natural uranium is U-235, but reactor fuel must consist of at least 3 percent to 5 percent U-235. A process called enrichment is used to increase the amount of U-235.
This enriched uranium is then fabricated into ceramic pellets that are about the size of a pencil eraser and then placed into rods. The rods are combined to form bundles, which are then grouped together to form the reactor’s core.
The reaction that ultimately generates electricity starts when an atom of U-235 absorbs a neutron and splits. The process of splitting atoms expels a tremendous amount of heat, some fission byproducts, and more neutrons, which are then absorbed by other uranium atoms. The process is repeated in a chain reaction that is controlled by control rods that are inserted into the reactor core.
The heat produced is used to heat water until it turns to steam. The steam turns a turbine, which in turn powers a generator to create nearly 20 percent of the electricity consumed inAmerica.
Outside the Reactor
Reactors are enclosed within thick steel pressure reactor vessels, which are protected with concrete shielding and enclosed in containment structures made of steel and reinforced concrete that are several feet thick. These layers of defense protect the reactor from outside threats like earthquakes or other natural disasters and the public and environment from the radiation within the reactor.
Other important buildings on a nuclear power plant site include the generating room and the iconic cooling towers (though not every plant uses cooling towers). Though the anti-nuclear crowd likes to show billowing cooling towers as symbolic of the dangers of nuclear energy, these are harmless giants that simply cool the superheated water. The vapor that emerges from the towers is not radioactive; rather, it is condensation of the water taken in from a nearby lake or river.
Americahas been pursuing and perfecting nuclear energy for over 50 years. Despite competitors such as natural gas, public relations disasters such asThree Mile Island, and cost-inflating government policies, nuclear energy continues to grow. Indeed, five reactors are under construction in theU.S.today.
Over the decades, the industry has become safer while at the same time becoming more efficient: In 1980, the average capacity factor (a measure of power actually produced over a specified period of time versus a generator’s theoretical capacity) was 56.3 percent, whereas in 2011 it was 89 percent.
Though the nuclear industry faces some significant challenges—such as nuclear waste storage—nuclear power’s future is bright.
Learn more about nuclear power plants and the important role they play in the new video “How a Nuclear Plant Works.” Heritage also explores the science behind nuclear energy and its role in the American energy landscape in the 40-minute film Powering America.