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Electrochemistry of uranium in molten LiCl-LiF

Geran, Sylvain and Chamelot, Pierre and Serp, Jérome and Gibilaro, Mathieu and Massot, Laurent Electrochemistry of uranium in molten LiCl-LiF. (2020) Electrochimica Acta, 355. 136784. ISSN 0013-4686

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Official URL: https://doi.org/10.1016/j.electacta.2020.136784

Abstract

This work is focused on the electrochemical behaviour of uranium in molten eutectic LiCl–LiF (70–30 mol%) in the 550–650 °C temperature range. On tungsten electrode, U(III) ions were reduced in one step to U metal exchanging 3 electrons and oxidized also in one step to U(IV) exchanging one electron. Both systems were studied by cyclic and square wave voltammetries and chronopotentiometry. The re- duction and oxidation mechanisms of U(III) ions were found to be diffusion controlled processes. The diffusion coefficient of U(III) was measured at different temperatures, and it followed an Arrhenius “type law”. Apparent standard potentials were measured in chloride-fluoride (LiCl-LiF eutectic) and pure chlo- ride media (LiC-KCl eutectic). The addition of fluoride ions into a chloride salt leads to the formation of more stable complexes reduced at more negative potentials. This shift of reduction potentials is more pronounced for the U(IV)/U(III) transition (~ 500 mV) than for the U(III)/U system (~ 100 mV).

Item Type:Article
HAL Id:hal-03118790
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Commissariat à l'Energie Atomique et aux énergies alternatives - CEA (FRANCE)
French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
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Deposited On:22 Jan 2021 14:27

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