lee wrote on Jul 25
th, 2017 at 10:13pm:
by electrical conductivity?
By radioactivity from: uranium, sulphate and radium contaminants.
http://www.world-nuclear.org/information-library/nuclear-fuel-cycle/mining-of-ur...The uranium orebody contains both
U-235 and (mostly)
U-238. About 95% of the radioactivity in the ore is from the U-238 decay series. This has
14 radioactive isotopes in secular equilibrium, thus each represents 7% of the total. (In the case of Ranger ore – with
0.3% U308 – it has about 450 kBq/kg, so irrespective of the mass proportion, 32 kBq/kg per nuclide in that decay series.) When the ore is processed, the U-238 and the very much smaller masses of
U-234 (and the U-235) are removed. The balance becomes tailings, and at this point has about 86% of its original intrinsic radioactivity. However, with the removal of most U-238, the following two short-lived decay products (
Th-234 & Pa-234) soon disappear, leaving the tailings with a little over 70% of the radio-activity of the original ore after several months. The controlling long-lived isotope then becomes
Th-230 which decays with a half life of 77,000 years to
radium-226 followed by
radon-222.
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