Article Dans Une Revue Electrochimica Acta Année : 2007

Reduction process of uranium(IV) and uranium(III) in molten fluorides

Résumé

This study focused on the electroreduction process of uranium cations in molten fluorides. It involved cyclic voltammetry, chronopotentiometry with and without current reversal, and square wave voltammetry. The results indicate a two-step reduction process for uranium(IV). The first step U(IV)/U(III) exchanging one electron corresponds to a soluble/soluble system and is limited by U(IV) diffusion with DU(IV) = 1.25 ± 0.35 × 10−5 cm2 s−1 in LiF–NaF at 720 ◦C. In order to perform a thorough study of the second step U(III)/U(0) in the reduction process, the melt was chemically reduced in U(III) with U metal as reducing agent. Alternatively to the use of LiF–NaF where U metal is unstable at 720 ◦C, the chemical reduction of U(IV) in U(III) was performed in a LiF–CaF2–UF4 solution containing U metal at 810 ◦C. It has been confirmed that the reduction of U(III) proceeds in one step exchanging three electrons and by a diffusion controlled process with DU(III) = 2.2 ± 0.7 × 10−5 cm2 s−1 in LiF–CaF2 at 810 ◦C.

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Dates et versions

hal-04618917 , version 1 (20-06-2024)

Identifiants

Citer

C. Hamel, P. Chamelot, A. Laplace, E. Walle, O. Dugne, et al.. Reduction process of uranium(IV) and uranium(III) in molten fluorides. Electrochimica Acta, 2007, 52 (12), pp.3995-4003. ⟨10.1016/j.electacta.2006.11.018⟩. ⟨hal-04618917⟩
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