A Battle Over Uranium Bodes Ill for U.S. Debate

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Radionuclides contained in uranium tailings emit 20 to 100 times as much gamma-radiation as natural background levels on deposit surfaces. Gamma radiation levels decrease rapidly with distance from the pile.
The radium-226 in tailings continuously decays to the radioactive gas radon-222, the decay products of which can cause lung cancer. Some of this radon escapes from the interior of the pile. Radon releases are a major hazard that continues after uranium mines are shut down. The U.S. Environmental Protection Agency (EPA) estimates the lifetime excess lung cancer risk of residents living nearby a bare tailings pile of 80 hectares at two cases per hundred.
Since radon spreads quickly with the wind, many people receive small additional radiation doses. Although the excess risk for the individual is small, it cannot be neglected due to the large number of people concerned. EPA estimates that the uranium tailings deposits existing in the United States in 1983 would cause 500 lung cancer deaths per century, if no countermeasures are taken.



Tailings deposits are subject to many kinds of erosion. Due to the long half-lives of the radioactive constituents involved, safety of the deposit has to be guaranteed for very long periods of time.
After rainfall, erosion gullies can form; floods can destroy the whole deposit; plants and burrowing animals can penetrate into the deposit and thus disperse the material, enhance the radon emanation and make the deposit more susceptible to climatic erosion.
When the surface of the pile dries out, the fine sands are blown by the wind over adjacent areas. The sky has darkened from storms blowing up radioactive dust over villages located in the immediate vicinity of Wismut's uranium mill tailings piles. Subsequently, elevated levels of radium-226 and arsenic were found in dust samples from these villages.



Seepage from tailings piles is another major hazard. Seepage poses a risk of contamination to ground and surface water. Residents are also threatened by radium-226 and other hazardous substances like arsenic in their drinking water supplies and in fish from the area. The seepage problem is very important with acidic tailings, as the radionuclides involved are more mobile under acidic conditions. In tailings containing pyrite, acidic conditions automatically develop due to the inherent production of sulfuric acid, which increases migration of contaminants to the environment.

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