Electrochemical Characterization and Selective Electrodeposition of Uranium and Cerium in LiF-BeF 2 -CeF 3 -UF 4 Molten Salt for MSR Applications

This study provides the first experimental confirmation of Be 13 Ce and Be 13 U intermetallic formation in a representative molten salt reactor (MSR) fuel salt, enabling two complementary electrochemical pathways for selective U/Ce separation: uranium recovery on inert Mo/Ni electrodes and cerium extraction on reactive Al electrodes. Cyclic voltammetry and chronopotentiometry reveal reversible redox couples for Ce(IV)/Ce(III) ( E 1 / 2 = 3.090 V), U(IV)/U(III) ( E 1 / 2 = 0.701 V), and U(III)/U ( E eq = 0.186 V) at 873 K, with diffusion coefficients of 1.54 × 10⁻ 6 cm 2 s⁻ 1 (U(IV)) and 2.92 × 10⁻ 5 cm 2 s⁻ 1 (Ce(III)). We confirmed the formation of Be 13 U and Be 13 Ce intermetallics, showing preferential Be 13 U formation suppresses Ce codeposition on Mo and Ni electrodes. Aluminum electrodes selectively extract Ce as Al 11 Ce 3 , enabling efficient Ce/U separation. These findings provide fundamental insights into actinide/lanthanide partitioning and establish a practical foundation for online reprocessing of molten salt reactor fuels.