The nation’s nuclear power plants are among the safest and most secure industrial facilities in the United States. Multiple layers of physical security—together with high levels of operational performance—protect plant workers, the public and the environment.
The U.S. Nuclear Regulatory Commission (NRC) regulates the commercial and institutional uses of nuclear energy, including nuclear power plants. The NRC monitors plant performance according to three strategic areas: reactor safety, radiation safety and security. Independent NRC inspectors at each plant provide daily oversight of plant operation, maintenance, equipment replacement and training.
Nuclear power plants are fueled with uranium. The uranium atoms split—a process called fission—producing heat that boils water to produce steam. The steam is used to spin a turbine to generate electricity. The leftover radioactive materials—a by-product of nuclear fission—are carefully controlled to be sure no dangerous levels of radiation get outside the plant.
Nuclear plant designers account for the possibility that equipment may fail and human mistakes can happen; therefore, multiple redundant backup systems and automatic processes are in place to minimize any problem that may occur. Nuclear power plants have built-in sensors to watch temperature, pressure, water level and all other operating indicators that are important to safety. These sensors are linked to control systems that adjust or shut down the nuclear reactor— immediately and automatically—at the first sign of an abnormality. In addition to backup systems that monitor and regulate what goes on inside the nuclear reactor, U.S. nuclear power plants also use a series of physical barriers—known as defense-in-depth—to prevent the escape of radioactive material.
- The first barrier is the nuclear fuel itself. The uranium fuel is in the form of solid ceramic pellets. Most of the radioactive by-products of the fission process remain locked inside the fuel pellets.
- The next barrier is the fuel rods, which hold the fuel pellets. They are made of a zirconium alloy that is resistant to heat, radiation and corrosion.
- The fuel rods are inside a large steel pressure vessel, with walls about eight inches thick.
- Finally, these barriers are enclosed in a massive reinforced concrete structure—called the containment—with walls that are about four feet thick. To reach the environment, radioactive material would have to escape from each of these barriers in succession.
The people who work at nuclear power plants recognize that nothing matters more than safety. They are trained and tested continually to make sure they understand the plant, follow procedures and pay strict attention to detail. The NRC requires all plant operators to pass difficult licensing—and re-licensing—exams. There are NRC inspectors monitoring daily operations at each of the more than 100 U.S. nuclear power plants. The NRC also conducts regular—and unannounced—inspections which cover all plant operations.