About Radiation

  1. Facts about radiation
  2. Naturally occurring radiation
  3. Ionizing radiation
  4. Human-made radiation
  5. Measuring radiation
  6. Effects of radiation
  7. Contamination and radiation
  8. Radiation source chart

Facts about radiation

Radiation is not new or limited to nuclear-power plants. Each of us is exposed to some radiation every moment of our lives from radioactive materials all around us.

Naturally occuring radiation

The sun covers the earth with cosmic radiation. Some rocks and minerals give off small amounts of radiation, such as radon gas. Radioactive particles are in the air and in our food and water. Many building materials also contain radiation. Even our bodies are mildly radioactive. All together, radiation from these sources is called natural background radiation.

Ionizing radiation

Although the term radiation is very broad and includes such things as light, heat, and radio waves, it is most often used to mean “ionizing” radiation. This is radiation that can produce charged particles, called “ions,” in materials it strikes.

Human-made radiation

Ionizing radiation also comes from human sources. It is used in the medical field to diagnose and treat disease. Science and industry use radiation for research and to x-ray welds, for example. Other human-made sources include color TV, smoke detectors, some luminous-dial watches and clocks, and nuclear power.

Measuring radiation

Like radio waves, ionizing radiation is invisible, silent, tasteless, and odorless. But it can be measured with special instruments. To measure the amount of radiation a person receives, a unit called a millirem (mrem) is used. One mrem is quite small. It's equal to:

  • moving to a ground elevation 100 feet higher for a year
  • viewing color TV an hour a day for a year
  • spending five days in the mountains
On average, a person living in the U.S. receives about 360 mrem per year from all radiation sources. Because of the low elevation and absence of radioactive geologic formations, a person living within 10 miles of the Cook Nuclear Plant receives an average of about 175 mrem per year from both natural and human-made radiation sources. Such low-level radiation is not considered harmful and is well below the safe limits of 5,000 mrem per year set by the Nuclear Regulatory Commission (NRC) for nuclear-plant workers.

Effects of radiation

Just as too much exposure to the sun can cause painful sunburn, too much exposure to certain levels and types of radiation can have harmful effects. But it takes radiation doses of over 20,000 mrem, received within a day, to produce effects measurable by a trained doctor. Very large doses of 50,000 to 100,000 mrem are required before an individual feels any ill effects. Harm from radiation depends on:

  • the length of time you are exposed
  • how far you are from the source
  • the amount your body is exposed to and which part
  • how much material you inhale or take into your body

Your health or physical condition can affect your reaction to radiation exposure, too. For example, parents should be aware that unborn babies and very young children are more likely than others to be harmed by radiation exposure.

Obviously, the less radiation you are exposed to, the less chance you have of receiving any harmful effects. It's for this reason that emergency planning takes place in and around nuclear power plants. Like so many things we live with, radiation need not be harmful if treated with caution and common sense.

Cook Nuclear Plant workers often check radiation levels both inside and outside the plant. If an accident did happen, state and federal health experts also would be called in to take radiation readings beyond the plant site boundary. These readings would determine what steps, if any, you and your family or fellow workers would need to take to protect yourselves.

Contamination and radiation

The term “contamination” means, quite simply, radioactive material is where it is not supposed to be. Food, water, or air is considered contaminated if it contains more or different types of radioactive material than would be normally present.

Our bodies, for example, contain very small amounts of the radioactive elements potassium 40, carbon 14 and tritium. However, we are not considered to be contaminated because these elements exist within us naturally.

On the other hand, the presence of strontium 90 (a possible byproduct of a nuclear-power plant accident) in food, air, or water may be indicative of contamination.

“Radiation” refers to the particles and waves given off by radioactive material. The radiation given off by contaminants could be considered harmful if the levels are high enough and the exposure lasts long enough.

Radiation sources could include:

Natural background radiation

mrem per year
Air 200
Food & Water 40
Cosmic 25-30
Earth 28
Building Materials 7-10
Human-made radiation
Chest x-ray 10-20
Coast-to-coast Airline flight 5
Viewing color TV one hour per day 1
Living next to Cook Plant less than 1

If you have questions or comments about anything in this part of the site, need more information about emergency planning, or want copies of the Emergency Planning Calendar, call or write either of the offices below.

Cook Energy Information Center
One Cook Place
Bridgman, Michigan 49106

Berrien County Emergency Management
Division of Berrien County Sheriff's Office
919 Port Street
St. Joseph, Michigan 49085
(269) 983-7141 Ext. 7215

This Emergency Information was prepared by American Electric Power in cooperation with the Berrien County Emergency Management Office and the Emergency Management Division of the Michigan Department of State Police.