Nuclear reactors and power plants have complex safety and security features
An uncontrolled nuclear reaction could result in widespread contamination of air and water. The risk of this happening in the United States is small because of:
- Diverse barriers and safety systems at nuclear power plants
- Training and skill of reactor operators
- Testing and maintenance activities
- Regulatory requirements and oversight of the U.S. Nuclear Regulatory Commission
In addition, a large area around a nuclear power plant must be restricted and guarded by armed security teams. U.S. reactors also have containment vessels designed to withstand extreme weather events and earthquakes.
A containment dome on a nuclear reactor
Source: Stock photography (copyrighted)
Nuclear power reactors do not produce carbon dioxide emissions
Unlike fossil fuel-fired power plants, nuclear reactors do not produce air pollution or carbon dioxide while operating. However, the processes for mining and refining uranium ore and making reactor fuel all require large amounts of energy. Nuclear power plants are constructed with large amounts of metal and concrete, which require large amounts of energy to manufacture. The emissions associated with the fossil fuels burned to mine and refine uranium ore and to construct the nuclear power plant could be associated with the electricity that nuclear power plant generates.
Nuclear energy produces radioactive waste
A major environmental concern related to nuclear power is creating radioactive waste such as uranium mill tailings, spent (used) reactor fuel, and other radioactive waste. These materials can remain radioactive and dangerous to human health for thousands of years. Radioactive waste is subject to special regulations that govern its handling, transportation, storage, and disposal. The U.S. Nuclear Regulatory Commission (NRC) regulates nuclear power plant operations.
Radioactive waste is classified as either low-level waste or high-level waste. The radioactivity of the waste can range from a little higher than natural background levels, such as for uranium mill tailings, to the much higher radioactivity of used (spent) reactor fuel and parts of nuclear reactors. The radioactivity of nuclear waste decreases over time through a process called radioactive decay. The amount of time it takes for the radioactivity of radioactive material to decrease to half its original level is called the radioactive half-life. Radioactive waste with a short half-life is often stored temporarily before disposal to reduce potential radiation doses to workers who handle and transport the waste. This storage system also reduces the radiation levels at disposal sites.
By volume, most of the waste related to the nuclear power industry has relatively low radioactivity. Uranium mill tailings contain the radioactive element radium, which decays to produce the radioactive gas radon. Most uranium mill tailings are stored near the processing facility, or mill, where they come from. Uranium mill tailings are covered with a sealing barrier, such as clay, to prevent radon from escaping into the atmosphere. The sealing barrier is covered by a layer of soil, rocks, or other materials to prevent the sealing barrier from eroding.
Other types of low-level radioactive waste are the tools, protective clothing, wiping cloths, and other disposable items that become contaminated with small amounts of radioactive dust and particles at nuclear fuel processing facilities and nuclear power plants. These materials are subject to special regulations for their handling, storage, and disposal to prevent contact with the outside environment.
High-level radioactive waste consists of irradiated, or spent, nuclear reactor fuel (fuel that is no longer useful for producing electricity). The spent reactor fuel is in a solid form, consisting of small fuel pellets in long metal tubes called rods.
Spent reactor fuel and decommissioned reactors have special rules
Spent reactor fuel assemblies are highly radioactive and, initially, must be stored in specially designed pools of water. The water cools the fuel and acts as a radiation shield. Spent reactor fuel assemblies can also be stored in specially designed dry storage containers. An increasing number of reactor operators store their older spent fuel in dry storage facilities using special outdoor concrete or steel containers with air cooling. The United States does not have a permanent disposal facility for high-level nuclear waste.
When a nuclear reactor stops operating, it must be decommissioned. Decommissioning involves safely removing the reactor and all equipment that has become radioactive and reducing radioactivity to a level that permits other uses of the property. The U.S. Nuclear Regulatory Commission has strict rules governing nuclear power plant decommissioning that involve cleaning up radioactively contaminated power plant systems, fuel, and structures.
