About Radiation

What is radiation?


Radiation is a form of energy that is a part of our everyday lives.  All of us receive a "dose" of radiation each day.  Most of the dose comes from naturally occurring radioactive materials such as uranium, thorium, radon, and certain forms of potassium and carbon.  The air we breathe contains radon, the food we eat contains uranium and thorium from the soil, and our bodies contain radioactive forms of potassium and carbon.  Cosmic radiation from the sun also contributes to our natural radiation dose. 


We also receive radiation doses from man-made sources such as X-rays, nuclear medical procedures, power plants, smoke detectors and older television sets.  Some people, such as nuclear plant operators, flight crews, and nuclear medicine staff may also receive an occupational radiation dose.


Measuring Dose


Radiation doses are normally measured in a unit called the rem.  The dose is based both on the amount of radiation received by an individual and the biological effect associated with the particular type of radiation. Since our radiation doses are normally very small, we usually record the dose in millirem (mrem).  One rem equals 1,000 mrem.


Most of us receive about 360 mrem a year from the radioactive sources listed above. About 300 mrem comes from natural sources, and the other 60 mrem from man-made sources.  To put this in perspective, the average dose from a chest X-ray is about 10 mrem, and we get about 3 mrem when we make a cross country flight.


The DOE has established a 100-millirem dose limit to members of the public from exposure pathways that are the result of its operations. The maximum dose any member of the public could have possibly received from normal operations on the Oak Ridge Reservation in 2004 was 12 mrem. This includes eating deer, turkey, fish, and geese harvested on or near the Reservation; drinking the most contaminated water; and breathing the most contaminated air. It is very unlikely any one person could have actually received this dose.


Types of Radiation


You may be familiar with some of the common types of radiation: alpha and beta particles, gamma rays and neutrons. Alpha and beta particles are usually hazardous only if inhaled or ingested. Gamma rays and neutrons can penetrate the body from the outside. All radioactive materials emit at least one of these radiations. If a nuclear emergency occurs in Oak Ridge, it is not necessary to remember the differences in the types of radiation, since all of the types could be encountered. 


A Nuclear Emergency in Oak Ridge?


While it is possible that a nuclear emergency impacting the Oak Ridge area could occur, it is not likely. Even if there is a nuclear emergency, most members of the public would not be expected to receive a radiation dose. For those people who did, the average doses would be expected to be less than the 360 mrem the public receives each year.


Levels of Radiation: 

Gastrointestinal series (upper & lower): 1400 millirem

CT Scan (head & body): 1100 millirem
Radon in average household: 200 millirem/year

Plutonium-powered pacemaker: 100 millirem/year

Natural radioactivity in your body: 40 millirem/year
Cosmic radiation: 31 millirem/year

Mammogram: 30 millirem

Smoking Cigarettes (1 pack/day): 15-20 millirem/year

*Maximum possible from normal operations on the Oak Ridge Reservation: 12 millirem/year

Consumer products: 11 millirem/year

Chest X-ray: 10 millirem

Dental X-ray: 10 millirem

Using natural gas in the home: 9 millirem/year

Road construction material: 4 millirem/year

Living near a nuclear power station: 1 millirem/year

Air travel (every 2006 miles): 1 millirem

*Source, 2004 DOE Annual Site Environmental Report Summary





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