Updated Oct. 2018
Radiation is a natural part of our environment. We are exposed to radiation every day through the sun’s rays and Earth’s crust; even our bodies give off small amounts of radiation. Smoke detectors, some wristwatches, exit signs and many other manmade devices use radioactive materials.
But when it comes to nuclear power plants, there are still a lot of misconceptions. We're answering the 10 most frequently asked questions about radiation.
1. What is radiation?
Radiation is energy in the form of waves or particles given off by unstable atoms. Radiation exists all around us.
2. Does radiation glow?
The idea of green goo glowing in test tubes comes from Hollywood and the Simpsons, not reality. However, in some cases, radiation does cause a light blue glow. This radiation is called Cherenkov radiation. When extremely radioactive material is placed underwater (like in a nuclear reactor) it can produce a blue glow. The glow is an optical shockwave, like a sonic boom that occurs when charged particles are emitted faster than the speed of light in water.
3. How can exposure occur?
People are exposed to small amounts of radiation every day from natural and man-made sources. Exposure occurs when radiation penetrates the body. For example, when a person has an X-ray, that person is exposed to radiation. Click here to see other ways radiation fits into our daily lives.
4. How much radiation does an American receive, on average, every year?
Radiation is measured in units called rems and millirems. The rem is a unit of measurement that takes into account the effect different types of radiation have on the body. A millirem is 1/1000th of a rem.
An American receives an average of 620 mrem of radiation every year. By comparison, a cross-country flight, round trip, exposes passengers to four mrem. Our bodies dispose of radiation like other wastes.
5. How much radiation comes from nuclear power plants?
Radiation is part of everyday life at a nuclear power plant. However, nuclear power plants release an extremely small dose of radiation. If you lived outside the gate of a nuclear power plant, 24 hours a day for a year, you would receive less than one mrem of radiation. To put this in perspective, living in a brick home for a year will expose you to 10 mrem of radiation.
6. How is radiation used in other industries?
Radiation is a valuable tool in many industries. It can help manage illnesses, like cancer. Doctors use high-energy radiation to shrink tumors and kill cancer cells. Roughly half of all cancer patients receive some type of radiation therapy during the course of their treatment.
Another industry that uses radiation is the mail system. The U.S. Post Office uses radiation to kill organisms in or on envelopes and packages, like anthrax, to protect postal workers and mail recipients.
7. Which organizations regulate radiation?
The United States has several agencies that cover various aspects of radiation and types of exposures. The Nuclear Regulatory Commission (NRC) is the main regulator for nuclear power plants. The NRC sets standards on how personnel work with radioactive materials and dose limits. The Food and Drug Administration (FDA) is responsible for the manufacture and sale of devices that emit radiation (such as X-ray machines). State health departments regulate the use of radioactive materials that concern the public; and the Environmental Protection Agency (EPA) regulates radioactive waste.
8. What is the difference between radiation and contamination?
Although the words “radiation” and “contamination” are used interchangeably, they have two very different meanings. “Contamination” refers to particles of radioactivity that are deposited where they are not supposed to be. Nuclear personnel take many steps to ensure contamination does not occur, including using protective clothing and equipment, undergoing scans for contamination before exiting the plant and following rigorous procedures.
9. What is radon?
Radon is a naturally-occurring radioactive gas. Radon, which is odorless, tasteless and invisible, is produced by the decay of uranium in soil and water. Most exposure to radon is from basements in homes, where the gas becomes trapped and concentrated. The EPA recommends testing your home for radon gas and offers local information on radon and test kits.
10. How far does radiation travel?
The distance radiation travels depends largely on the type of radiation. Alpha and beta particles do not travel far at all and can be blocked easily. X-ray, gamma and neutron radiation travel a significantly farther distance and need strong barriers (like those nuclear power plants are made of) to stop them.
For more information on radiation, check out the NRC's Frequently Asked Questions About Radiation.