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Exploring the Change in Redox Reactivity of UO(2) Induced by Exposure to Oxidants in HCO(3)(–) Solution

[Image: see text] Understanding the possible change in UO(2) surface reactivity after exposure to oxidants is of key importance when assessing the impact of spent nuclear fuel dissolution on the safety of a repository for spent nuclear fuel. In this work, we have experimentally studied the change in...

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Autores principales: Li, Junyi, Liu, Xianjie, Jonsson, Mats
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2023
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10189733/
https://www.ncbi.nlm.nih.gov/pubmed/37128775
http://dx.doi.org/10.1021/acs.inorgchem.3c00682
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author Li, Junyi
Liu, Xianjie
Jonsson, Mats
author_facet Li, Junyi
Liu, Xianjie
Jonsson, Mats
author_sort Li, Junyi
collection PubMed
description [Image: see text] Understanding the possible change in UO(2) surface reactivity after exposure to oxidants is of key importance when assessing the impact of spent nuclear fuel dissolution on the safety of a repository for spent nuclear fuel. In this work, we have experimentally studied the change in UO(2) reactivity after consecutive exposures to O(2) or γ-radiation in aqueous solutions containing 10 mM HCO(3)(–). The experiments show that the reactivity of UO(2) toward O(2) decreases significantly with time in a single exposure. In consecutive exposures, the reactivity also decreases from exposure to exposure. In γ-radiation exposures, the system reaches a steady state and the rate of uranium dissolution becomes governed by the radiolytic production of oxidants. Changes in surface reactivity can therefore not be observed in the irradiated system. The potential surface modification responsible for the change in UO(2) reactivity was studied by XPS and UPS after consecutive exposures to either O(2), H(2)O(2), or γ-radiation in 10 mM HCO(3)(–) solution. The results show that the surfaces were significantly oxidized to a stoichiometric ratio of O/U of UO(2.3) under all the three exposure conditions. XPS results also show that the surfaces were dominated by U(V) with no observed U(VI). The experiments also show that U(V) is slowly removed from the surface when exposed to anoxic aqueous solutions containing 10 mM HCO(3)(–). The UPS results show that the outer ultrathin layer of the surfaces most probably contains a significant amount of U(VI). U(VI) may form upon exposure to air during the rinsing process with water prior to XPS and UPS measurements.
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spelling pubmed-101897332023-05-18 Exploring the Change in Redox Reactivity of UO(2) Induced by Exposure to Oxidants in HCO(3)(–) Solution Li, Junyi Liu, Xianjie Jonsson, Mats Inorg Chem [Image: see text] Understanding the possible change in UO(2) surface reactivity after exposure to oxidants is of key importance when assessing the impact of spent nuclear fuel dissolution on the safety of a repository for spent nuclear fuel. In this work, we have experimentally studied the change in UO(2) reactivity after consecutive exposures to O(2) or γ-radiation in aqueous solutions containing 10 mM HCO(3)(–). The experiments show that the reactivity of UO(2) toward O(2) decreases significantly with time in a single exposure. In consecutive exposures, the reactivity also decreases from exposure to exposure. In γ-radiation exposures, the system reaches a steady state and the rate of uranium dissolution becomes governed by the radiolytic production of oxidants. Changes in surface reactivity can therefore not be observed in the irradiated system. The potential surface modification responsible for the change in UO(2) reactivity was studied by XPS and UPS after consecutive exposures to either O(2), H(2)O(2), or γ-radiation in 10 mM HCO(3)(–) solution. The results show that the surfaces were significantly oxidized to a stoichiometric ratio of O/U of UO(2.3) under all the three exposure conditions. XPS results also show that the surfaces were dominated by U(V) with no observed U(VI). The experiments also show that U(V) is slowly removed from the surface when exposed to anoxic aqueous solutions containing 10 mM HCO(3)(–). The UPS results show that the outer ultrathin layer of the surfaces most probably contains a significant amount of U(VI). U(VI) may form upon exposure to air during the rinsing process with water prior to XPS and UPS measurements. American Chemical Society 2023-05-02 /pmc/articles/PMC10189733/ /pubmed/37128775 http://dx.doi.org/10.1021/acs.inorgchem.3c00682 Text en © 2023 The Authors. Published by American Chemical Society https://creativecommons.org/licenses/by/4.0/Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Li, Junyi
Liu, Xianjie
Jonsson, Mats
Exploring the Change in Redox Reactivity of UO(2) Induced by Exposure to Oxidants in HCO(3)(–) Solution
title Exploring the Change in Redox Reactivity of UO(2) Induced by Exposure to Oxidants in HCO(3)(–) Solution
title_full Exploring the Change in Redox Reactivity of UO(2) Induced by Exposure to Oxidants in HCO(3)(–) Solution
title_fullStr Exploring the Change in Redox Reactivity of UO(2) Induced by Exposure to Oxidants in HCO(3)(–) Solution
title_full_unstemmed Exploring the Change in Redox Reactivity of UO(2) Induced by Exposure to Oxidants in HCO(3)(–) Solution
title_short Exploring the Change in Redox Reactivity of UO(2) Induced by Exposure to Oxidants in HCO(3)(–) Solution
title_sort exploring the change in redox reactivity of uo(2) induced by exposure to oxidants in hco(3)(–) solution
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10189733/
https://www.ncbi.nlm.nih.gov/pubmed/37128775
http://dx.doi.org/10.1021/acs.inorgchem.3c00682
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