Title: Surface alteration evidence for a mechanism of anoxic dissolution of UO2
Authors: POPEL ALEKSEJ J.TAN BENG THYEGOUDER THOMASLAMPRONTI GIULIO I.DAY JASONELOIRDI RACHELSEIBERT ALICEFARNAN IAN
Citation: APPLIED SURFACE SCIENCE vol. 464 p. 376-379
Publisher: ELSEVIER SCIENCE BV
Publication Year: 2019
JRC N°: JRC111625
ISSN: 0169-4332 (online)
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC111625
DOI: 10.1016/j.apsusc.2018.09.094
Type: Articles in periodicals and books
Abstract: A secondary phase has been observed to nucleate on the surface of UO2 in a solution with uranium concentration values of ∼10−9 mol/l. The UO2 was in the form of a 100 nm single crystalline film of UO2 epitaxially deposited on the (0 0 1) surface of a single crystalline silicon substrate. An extended (140 days) dissolution experiment with UO2 in contact with a solution in deoxygenated, deionised water, under an Ar atmosphere (∼0.1 O2 ppm) at ambient temperature (∼25 °C) suggests that uranium dioxide should dissolve and precipitate while remaining in the U4+ oxidation state to enable nucleation of a low solubility secondary phase. A mechanism for the anoxic dissolution of UO2 in deionised water is proposed that involves U4+ dissolution at defect sites that subsequently nucleate and precipitate in a less defective form.
JRC Directorate:Nuclear Safety and Security

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