Federal regulations require a detailed assessment of environmental impacts associated with a nuclear energy facility before it can be licensed to operate.
Because an unintentional leak of radioactivity from nuclear plants is possible, the Nuclear Regulatory Commission (NRC) evaluates the potential impact of such leakage during the initial plant licensing process. The NRC conducted environmental assessments for all 104 operating reactors and is doing so for new reactors now in the licensing phase.
Electric power companies that operate nuclear energy facilities must begin radiological environmental monitoring at least three years before the plant begins operation, and must continue monitoring throughout the plant's lifetime.
Because radiation is naturally present in the environment, pre-operational monitoring establishes a baseline against which plant staff and the regulator can compare subsequent measurements.
The federal limit for annual radiation dose to the public from nuclear plant operations is 25 millirem. A REM (Roentgen Equivalent Man) is a unit of radiation exposure that indicates potential biological effect on human cells. A millirem is equal to one-thousandth of a rem. The average person receives about 300 millirems annually of naturally occurring background radiation from soil, rocks, consumer products, medical procedures, etc.
The average actual dose to the public from a nuclear power plant is about 2 millirem less than 10% of the regulatory limit.
Nuclear plants also are required to conduct radiological monitoring of air, water, land, food and produce grown near nuclear energy facilities.