Electrochemical behavior of plutonium fluoride species in LiF-CaF2 eutectic melt. (1st April 2019)

• Record Type: Journal Article
• Authors: Claquesin, Julien; Lemoine, Olivier; Gibilaro, Mathieu; Massot, Laurent; Chamelot, Pierre; Bourges, Gilles
• Is Part Of: Electrochimica acta. Volume 301(2019)
• Page Start: 80
• Page End: 86
• Publication Date: 2019-04-01
• Subjects: Molten fluoride -- Electrochemistry -- Plutonium -- Cyclic voltammetry -- Chronopotentiometry; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2019.01.169
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: The electrochemical behavior of plutonium fluoride species was investigated in molten LiF-CaF2 medium in the 1093–1153 K temperature range with PuF4 additions. A preliminary thermodynamic study supposed a Pu(IV) carboreduction into Pu(III) and that Pu(III) reduction into metal proceeds in one step. Then, an electrochemical study was carried out on an inert electrode (tungsten) and confirmed the thermodynamic predictions: Pu(IV) is spontaneously reduced into Pu(III) in presence of carbon and Pu(III) is directly reduced into Pu(0): Pu(III) + 3e − = Pu(0). Moreover, Pu(III) reduction mechanism is a diffusion controlled process. Diffusion coefficients were calculated at different temperatures and obey to an Arrhenius' type law with an activation energy of 63 ± 3 kJ mol −1 . The standard potential of Pu(III)/Pu(0) was determined at 1113 K and is found to be −4.61 V vs. F2 (gaz) /F − . This value permitted to calculate activity coefficients for several molalities.