Radioactive Materials: Environmental Radiation Monitoring FAQs - EH: Minnesota Department of Health

Environmental Radiation Monitoring FAQs

In the 1950s and 1960s, atmospheric testing of nuclear weapons introduced large amounts of radioactivity into the global environment. Currently, utility, industrial, medical, government, and academic organizations use and dispose of radioactive materials. Because radiation is known to cause cancer, it is prudent to monitor the environment for radioactivity.

Does Minnesota have an environmental radiation monitoring program?

Minnesota has maintained a radioactivity monitoring program since 1953, when measurements of radionuclides were initiated in response to atmospheric testing of nuclear weapons. The program was expanded to include monitoring around nuclear generating facilities: Elk River plant, 1961; Monticello plant, 1968; and Prairie Island plant, 1973 (The Elk River reactor was decommissioned in 1973).

What is environmental radiation monitoring?

Environmental radiation monitoring is the systematic collection and analysis of certain environmental media, such as air, milk, and water, to determine the level of radioactivity present. Levels of radioactivity are compared to safety standards to ensure a safe environment.

The current Minnesota Department of Health's environmental radiation monitoring program objectives are:

  • To detect any above normal levels of radioactivity in Minnesota.
  • To determine long-term trends so that any changes in the radiological environment are identified and corrective actions, if needed, are taken.
  • To compare against data collected by nuclear utilities.
  • To maintain a knowledge base for responding to nuclear materials accidents.

These objectives are met by sampling various environmental pathways for human exposure and directly measuring radiation levels near the plants and at other locations around the state.

The major pathways are:

  • Release » air » inhalation
  • Release » air » deposition » ingestion
  • Release » water » ingestion
  • Shine » air » direct whole body exposure

What are normal levels of radiation?

Natural radioactivity originates from radioactive elements in the earth's crust as well as extraterrestrial sources, such as cosmic rays. The normal level of natural radiation in Minnesota ranges from 200 to 400 millirem each year. As a rough approximation, the average is about one millirem per day. A "millirem" is one thousandth of a rem. Most of our natural exposure is due to radon, a gas which emanates from the earth's crust and is present in the air we breathe.

Where is environmental radiation monitoring currently performed?

Environmental monitoring is conducted near the Monticello and Prairie Island nuclear generating plants. Monitoring includes the collection and analysis of air, water and milk.

What types of radiation are looked for during monitoring?

There are four types of radiation being monitored:

  • Alpha particles. Alpha radiation is not considered an external hazard because the dead layer of skin will absorb all alpha particles with no harmful effect. However, if inhaled or ingested, it can be an internal hazard.
  • Beta particles. Beta radiation is considered a slight external hazard and is mainly a skin and internal exposure hazard.
  • Gamma rays. They are external hazards, which can penetrate materials and travel much farther in matter than alpha and beta particles.
  • Neutrons. They also penetrate material and are external hazards.

Is there a reason to be concerned about environmental radiation near the nuclear generating plants?

No unsafe levels of radioactivity or direct radiation have been detected near the Monticello and Prairie Island nuclear generating plants in Minnesota.

Updated Monday, 11-Mar-2019 11:53:08 CDT