The Basics
Nuclear energy comes from splitting atoms in a reactor to heat water into steam, turn a turbine and generate electricity. Today, 98 nuclear reactors in 30 states generate nearly 20 percent of the nation’s electricity without emitting carbon. And nuclear plants are always on, even during extreme weather, supporting the grid 24/7.
How a Nuclear Plant Works
Most power plants spin a turbine to generate electricity. Coal, natural gas, oil and nuclear energy use their fuel to turn water into steam and use that steam to turn a turbine.
Nuclear plants are different because they do not burn anything to create steam. Instead, they split uranium atoms in a process called fission. As a result—unlike other energy sources—nuclear power plants do not release carbon or pollutants like nitrogen oxide (NOx) and sulfur oxide (SO2) into the air.
Nuclear reactors are designed to sustain an ongoing chain reaction of fission; they are filled with a specially designed, solid uranium fuel and surrounded by water, which facilitates the process. When the reactor starts, uranium atoms split, releasing heat. This heat is used to create the steam that spins a turbine, which powers a generator to make electricity.
Nuclear Fuel
Nuclear fuel is solid when it goes in a reactor and solid when it comes out. It is arranged in fuel assemblies: sets of sealed metal tubes that hold ceramic uranium pellets.
Uranium is an abundant metal and full of energy: One uranium fuel pellet creates as much energy as one ton of coal, 149 gallons of oil or 17,000 cubic feet of natural gas. It does not come out of the ground ready to go into a reactor, though; it must undergo four major processing steps: mining and milling, conversion, enrichment and fuel fabrication.
Natural uranium is converted into several different forms to prepare it for enrichment. The enriched uranium is converted into a powder and then pressed into fuel pellets. The fuel fabricator loads these pellets into the fuel assemblies that are used in nuclear reactors.
Nuclear Waste
Once removed from a reactor, used fuel assemblies initially cool down in a storage pool. The concrete-and-steel pool and the water above the assemblies shield workers from radioactivity.
When cool enough that it no longer needs to be stored underwater—typically two to five years after removal from the reactor—used fuel is transferred and stored in dry casks, which are large steel-reinforced concrete containers. They’re safe enough to walk up to and touch.
The nuclear industry handles nuclear waste safely and in compliance with the stringent requirements of the U.S. Nuclear Regulatory Commission, the U.S. Department of Energy and the U.S. Environmental Protection Agency.
The NRC divides waste from nuclear plants into two categories: high-level and low-level waste.
- Low-level waste includes items like gloves, tools or machine parts that have been exposed to radioactive materials. Low-level waste is either stored on-site or collected and transported safely to disposal facilities in South Carolina, Washington, Utah or Texas.
- High-level waste is mostly used fuel from the reactor. A permanent disposal site for high-level waste has been planned for Yucca Mountain, Nevada, since 1987. If the federal government completes the project, DOE will transport and dispose of all U.S. commercial used fuel. Consolidated interim storage sites also have been proposed so that used fuel can be more efficiently managed until a permanent disposal site becomes available.
All of the used fuel ever produced by the commercial nuclear industry would cover a football field to a depth of less than 10 yards. That might seem like a lot, but coal plants generate that same amount of waste every hour.
Safety and Security
Nuclear power plants maintain the highest standard for operational safety, security and emergency preparedness. Robust physical defenses, redundant security systems and highly trained security officers protect our plants from threats. While advanced cybersecurity measures keep intruders out with layers of security and constant monitoring of new threats.
Nuclear plants are designed and licensed under an approach to safety called “defense-in-depth.” The key is multiple independent layers of protection. No single safety layer is exclusively relied upon, no matter how strong it is. Multiple physical barriers protect against an accidental radiation release, such as the rods that encase the uranium fuel and the steel-reinforced concrete building that houses the reactor.
The NRC enforces its safety and security regulations with inspections, can levy fines and can order a plant to shut down. Every nuclear plant is assigned at least two NRC inspectors, who are free to observe anything at the plant at any time.
U.S. commercial nuclear plants have a strong safety record: there have been no radiation-related health effects linked to their operation throughout the history of their operation.
Nuclear Energy Is Critical to Reducing Carbon Emissions
Our nation’s fleet of reactors produce more than 56 percent of the country’s emissions-free electricity.
Electricity generated with nuclear energy avoids the emissions of more than 555 million metric tons of carbon dioxide every year. That’s equivalent to the emissions from 117 million passenger vehicles—more than all of the passenger vehicles on the road in the U.S.—and more than hydropower, wind, solar and geothermal combined.
That’s a big reason why a growing group of companies, environmental groups and nongovernmental organizations has come forward to acknowledge that we will need help from America’s number one emissions-free energy source to find a viable, affordable solution to reducing emissions.
Nuclear Energy Helps Improve Air Quality
Nuclear can go further than any other energy source to reduce air pollution-related health problems caused by burning fossil fuels.
Nuclear plants generate electricity without the harmful byproducts that coal, oil and natural gas emit. These pollutants contribute to stroke, heart disease, neurological disease, lung cancer and respiratory diseases, including asthma.
While producing electricity, nuclear power plants do not emit:
- Nitrogen oxide, which produces smog
- Sulfur dioxide, which produces acid rain
- Particulate matter, like smoke and dust
- Mercury, a harmful neurotoxin.
Without nuclear power, NOx and SO2 levels in the U.S. would increase by more than 29 percent. By keeping existing nuclear power plants on line and building advanced nuclear facilities in the United States, we also protect the health of our communities.
A Strong Nuclear Industry Boosts National Security
A robust commercial nuclear industry can also help boost national security. That’s because American nuclear industry expertise and a robust commercial nuclear export sector helps us set the rules for international operational and safety practices, nuclear security, and nonproliferation.
Recently, Russia and China have made great strides in developing their nuclear industries, leaving them poised to take leading roles in the establishment of global nuclear norms and standards in the future. In response to this and other developments, a group of 77 dignitaries and national security experts signed a letter to Energy Secretary Rick Perry explaining the essential and unique national security benefits of having a strong and growing civil nuclear industry.
If America is to continue to set the global standard for nuclear safety, security and nonproliferation, our commercial nuclear industry needs to remain world-class.