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UO2 dissolution in Boom Clay conditions by C Cachoir; K Lemmens; S Van den Berghe; P Van Iseghem is a Materials Science article available to read on EtoBox.

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The solubility of uranium dioxide (UO 2 ) was measured in real and synthetic Boom Clay waters with varying concentrations of humic acids and carbonate under reducing conditions at 20 °C. Uranium concentrations in function of time suggest the reduction of U(VI) to U(IV) by the humic acids which is occurring faster in real clay water than in synthetic clay waters. Humic acids induce also a competition to complex U(VI) in carbonate-containing solution, but they are not able to control the uranium concentration at high bicarbonate concentration (0.02 mol dm À3 ). Nevertheless they may play a role at low carbonate concentration. In our experimental conditions, the geochemical calculations indicate that two uranium secondary phases (U 4 O 9 and UO 2ðcÞ ) are susceptible to control the uranium concentration in solution. These calculations are in good agreement with results of the X-ray photoelectron spectroscopy. At the end of tests, uranium concentrations reach steady-state values between 3 Â 10 À8 and 5 Â 10 À8 mol dm À3 in the bicarbonate-rich solutions. Although these concentrations are considered as conservative, they are 10-100 times higher than in natural Boom Clay. The consequence

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Author

C Cachoir; K Lemmens; S Van den Berghe; P Van Iseghem

Publisher

Elsevier Science; Elsevier ; Elsevier BV (ISSN 0022-3115)

Published

2003

Language

EN

Field

Materials Science (Physical Sciences)