Advances in Research on Uranium Isotope Fraction in Nature and Prospects

Abstract

Uranium is the heaviest naturally occurring radioactive element in nature, and it is widely distributed in the earth’s crust. With the improvement of the technical accuracy of mass spectrometry to measure uranium isotope ratios, it is gradually recognized that uranium isotopes in the natural environment also have fractionation effects. In this paper, the recent research results on uranium isotope fractionation is reviewed and the geochemical behavior of uranium in nature and the analytical methods of uranium isotopes is introduced. The natural uranium isotope fractionation is related to the nuclear volume effect, which leads to a greater tendency for heavy uranium isotopes to be enriched in the reductant equivalent, and the δ238U of U(Ⅵ) reduction to U(Ⅳ) reaches 1.0‰. The isotopic fractionation mechanism of uranium in redox exchange reactions is revealed by the sensitivity of uranium isotopes to the oxidation-reduction environment, and it is found that δ238U is significantly isotopically fractionated between deposits formed in different oxidation-reduction environments, and moreover, it is shown that the bioreduction-induced isotopic fractionation of uranium is greater. Therefore, uranium isotope fractionation has an important tracer role in the inversion of uranium ore formation environment and the study of radioactive environmental chemistry and environmental remediation in the in-situ leaching of uranium mining. Finally, how to better address the environmental remediation of groundwater in the in-situ leaching of uranium mining is suggested, thus promoting the research and application of uranium isotope systems in the field of earth sciences.

Keywords

• uranium isotope
• fractionation
• redox reduction