Quote:
Originally Posted by Donnie B.
On the other hand, much of the DU exposure is due to human activity. Before 1940 Uranium was rarely used for anything, and there was little mining. Today it's out of the ground and into the environment. It doesn't hurt to pay attention to any possible effects.
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It wasn't mined directly, but uranium was mined and excess uranium released into the environment long before 1940. From here:
http://www.ornl.gov/info/ornlreview/...t/colmain.html
Using these data, the releases of radioactive materials per typical plant can be calculated for any year. For the year 1982, assuming coal contains uranium and thorium concentrations of 1.3 ppm and 3.2 ppm, respectively, each typical plant released 5.2 tons of uranium (containing 74 pounds of uranium-235) and 12.8 tons of thorium that year. Total U.S. releases in 1982 (from 154 typical plants) amounted to 801 tons of uranium (containing 11,371 pounds of uranium-235) and 1971 tons of thorium. These figures account for only 74% of releases from combustion of coal from all sources. Releases in 1982 from worldwide combustion of 2800 million tons of coal totaled 3640 tons of uranium (containing 51,700 pounds of uranium-235) and 8960 tons of thorium.
Power plant capacity was smaller back before 1940, but they also had little control over particulate release. Further, you can find (naturally) a little uranium in your backyard, a little in seawater or a chunk of granite.
Certainly it's reasonable to be careful, but the evidence just doesn't point to some special danger in this case.