Radiation Protection

Radionuclide Basics: Uranium

Uranium (chemical symbol U) is a naturally occurring radioactive element. When refined, uranium is a silvery-white metal. Uranium has three primary naturally occurring isotopesisotopeA form of an element that has the same number of protons but a different number of neutrons in the nucleus, giving it a different atomic mass. For example, uranium has thirty-seven different isotopes, including uranium-235 and uranium-238.: U-238, U-235 and U-234.

Uranium is weakly radioactive and contributes to low levels of natural background radiationbackground radiationRadiation that is always in the environment. The majority of background radiation occurs naturally and a small fraction comes from man-made elements. in the environment. Uranium is used in nuclear power generation. Specifically, U-235 can be concentrated in a process called “enrichment,” making it "fissile" and suitable for use in nuclear reactors or weapons.

Type of Radiation Emitted:		Half-lifeHalf-lifeThe time required for half of the radioactive atoms present to decay or transform. Some radionuclides have half-lives of mere seconds, but others have half-lives of hundreds or millions of years.

Alpha ParticlesAlpha ParticleA form of particulate ionizing radiation made up of two neutrons and two protons. Alpha particles pose no direct or external radiation threat; however, they can pose a serious health threat if ingested or inhaled.	Gamma RaysGamma RaysA form of ionizing radiation that is made up of weightless packets of energy called photons. Gamma rays can pass completely through the human body; as they pass through, they can cause damage to tissue and DNA. (from radioactive decay products)	Uranium-238: 4.47 billion years Uranium-235: 700 million years Uranium-234: 244,000 years

Uranium in the Environment
Uranium Sources
Uranium and Health

Uranium is present naturally in virtually all soil, rock and water. Rocks break down to form soil. Soil can be moved by water and blown by wind, which moves uranium into streams, lakes and surface water. More than 99 percent of the uranium found in the environment is in the form of U-238. Uranium-234 is less than one percent of all forms of natural uranium, but is much more radioactive. It gives off almost half of the radioactivity from all forms of uranium found in the environment.

The U.S. mining industry can retrieve uranium in two ways. The first is to mine rock that contains uranium. The second is to use strong chemicals to dissolve uranium from underground rocks into ground water, and then pump the water to the surface. The waste from these processes is more radioactive than the natural rock because the natural radioactive material in the earth is now exposed and concentrated. This waste can contaminate water, soil and air if it is not disposed of properly. Uranium eventually decays to radium. Radium decays to release a radioactive gas called radon. Radon in underground uranium mines is a greater radiation hazard to miners than uranium. Without precautions (i.e. ventilation) radon can collect in the mine shafts where it is inhaled by miners. Learn more about uranium mines and mills.