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Fact Sheet on Environmental Monitoring

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The discharge of radioactive effluents from routine nuclear power plant operations can have environmental impacts – on man, animals, plants, and sea life. During the licensing of a nuclear plant, NRC issues a Final Environmental Impact Statement (FEIS), which identifies these potential impacts. As part of NRC's requirements for operating a nuclear power plant, licensees must:

  • keep releases of radioactive material to unrestricted areas during normal operation as low as reasonably achievable (as described in the Commission’s regulations in 10 CFR Part 50.36a), and
  • comply with radiation dose limits for the public (10 CFR Part 20).

In addition, NRC regulations require licensees to have various effluent and environmental monitoring programs to ensure that the impacts from plant operations are minimized. The permitted effluent releases result in very small doses to members of the public living around nuclear power plants.


Current regulations to limit offsite releases and their associated radiation doses are much more restrictive than those required for nuclear power plants licensed in the 1960s. In 1975, the NRC amended its regulations (10 CFR Parts 50.34 and 50.36 and a new Appendix I) to provide numerical guides for design objectives and limiting conditions for operation to meet the radiation dose criterion "as low as is reasonably achievable." Adoption of these regulations requires that plant releases be kept to doses well below the annual radiation exposure limits for the public of 0.1 rem in a year. [An average person in the United States receives a radiation dose of about 0.31 rem annually from natural or background radiation sources.]

The Environmental Protection Agency (EPA) sets the standards for other agencies that must then develop or revise their requirements to comply with the EPA standards. In late 1979, EPA placed an additional radiation dose requirement on reactor licensees to comply with EPA 40 CFR 190 whole body dose limits of 0.025 rem per year and 0.075 rem organ dose per year for members of the public. The NRC incorporated EPA's regulation into 10 CFR Part 20 in 1981, and all plants must now meet these requirements.

Monitoring Environmental Impacts

Environmental Monitoring

The NRC requires licensees to report plant discharges and results of environmental monitoring around their plants to ensure that potential impacts are detected and reviewed. Licensees must also participate in an inter-laboratory comparison program, which provides an independent check of the accuracy and precision of environmental measurements.

In annual reports, licensees identify the amount of liquid and airborne radioactive effluents discharged from plants and the associated doses. Licensees also must report environmental radioactivity levels around their plants annually. In order to gather the data for these reports, radiation levels are measured with TLDs (thermoluminescent dosimeters) and samples are collected from the air, surface water (such as ponds, streams and lakes) ground water, drinking water, shoreline sediment, milk, fish, vegetation, invertebrates and other medium in the environment that could be impacted by radioactive effluents. The results of this effort are published in the publically available annual reports.

The NRC conducts periodic onsite inspections of each licensee's radioactive effluent control program and environmental monitoring program once every two years, to ensure compliance with NRC requirements. NRC resident inspectors stationed at the site conduct inspections that are designed to ensure that the licensee effectively controls, monitors and quantifies releases of radioactive materials in liquid, gaseous and particulate forms to the environment. Inspections are also designed to ensure that radiological environmental monitoring programs are effectively implemented. The NRC documents the status of licensee effluent releases and the results of their environmental monitoring and assessment effort in publicly available inspection reports.

Environmental Monitoring

Over the past 25 years, radioactive effluents released from nuclear power plants have decreased significantly. During the early part of that period, a significant contributor to the reduction was the addition of special systems (augmented offgas systems) to boiling-water reactors, which process some of the noncondensible gases formed in the reactor process to limit the radioactive gases released to the environment. In recent years, improved fuel performance and licensees' improved effluent control programs further contributed to reducing radioactive effluents.

Tritium in Groundwater at Nuclear Plants

Recently, several nuclear power plants have detected tritium in groundwater monitoring wells, which caused the NRC and its licensees to take actions to address the source of the tritium (e.g., buried piping leaks) and to communicate the impact to the public and other external stakeholders. The NRC assesses licensee’s responses to leaks, and the nuclear industry has undertaken additional initiatives to address buried piping leaks. NRC actions in each individual case ensure the licensee investigates the source of contamination. To date, these tritium leaks have not posed a hazard to human health.

If the levels of radioactive materials in the environmental samples exceed the "reporting levels" specified in the radiological environmental monitoring program (REMP), the licensee is required to submit a report to the NRC that identifies the problem and defines how the problem will be corrected. The problem would also be required to be reported to the NRC in the licensee’s Annual Radiological Environmental Operating Report. These reports are publically available at the NRC web site. To access the report, select the nuclear plant site of interest and follow the links. The NRC performs routine inspections of licensees’ effluent and environmental monitoring programs to ensure that the regulatory requirements are met and that effluents are kept As Low As Is Reasonably Achievable.

November 2011

Page Last Reviewed/Updated Friday, December 12, 2014