Power Generation, Transmission, and Use

Markets, Regulation, and Oversight

Impacts of Power Generation and Transmission

Looking Ahead


CEIR Report Map


Maryland Power Plants and the Environment (CEIR-18)

4.5 Radiological Issues

4.5.1 Pathways to Exposure

Production of nuclear power in the United States is licensed, monitored, and regulated by the U.S. Nuclear Regulatory Commission (NRC). Provisions in the operating licenses of each plant allow utilities to discharge very low levels of radioactive material to the environment. The kind and quantity of releases are strictly regulated and must fall within limits defined in federal law as protective of human health and the environment. The NRC regulates releases from nuclear power plants according to the principle that the exposure of the environment and humans to radiation be kept “as low as reasonably achievable.”

Pathways of exposure to radioactive material in the environment are similar to those for other pollutants. An aqueous (water) pathway dose can be received internally or externally by ingesting contaminated water and seafood, or by exposure to contaminated sediments and water. An atmospheric pathway dose can result from exposure to or inhalation of radioactive gas or airborne particles, or ingestion of radionuclides deposited on or assimilated by terrestrial vegetation and animals.

Nuclear power plants are minor contributors to radiation exposure in the United States. As Figure 4-32 illustrates, natural radiation sources (radon and other background sources) account for nearly 50 percent of the average radiation dose to humans. Of the remaining radiation dose to humans that arises from man-made sources, less than 0.05 percent is attributed to commercial nuclear power production.

Figure 4-32 Annual Estimated Effective Dose Equivalent (mrem) to the General Population from Natural and Man-Made Sources

Figure 4-24

Source: National Council on Radiation Protection and Measurements, Ionizing Radiation Exposure of the Population of the United States, NCRP Report No. 160, 2009

As noted above, nuclear power plants such as Calvert Cliffs and Peach Bottom routinely release small quantities of gaseous, particulate, and liquid radioactive material into the atmosphere and adjacent waterways used for cooling water (e.g., Chesapeake Bay). The level of radioactivity in the effluent at any given time depends on many factors, including plant operating conditions and conditions of the nuclear fuel.

Most of the releases to the environment consist of radioactive noble gases into the atmosphere and tritium to waterways, neither of which have environmental significance since they are easily dispersed or are chemically inert. Aqueous discharges, however, may contain varying concentrations of radionuclides (e.g., iodine and metals such as iron, cobalt, cesium, chromium, zinc, and manganese) that can be accumulated by biota or become trapped in bottom sediments.  Over time, these radionuclides may potentially contribute to a radiation dose to humans by transport through the food chain. Total principal environmentally active radionuclide releases have declined over the past two decades due to improvements in coolant water filtration technology.