Electrochemical Mix‐Reduction Process of U and U‐Fe Alloys on the Surface of Cathode in LiCl‐KCl‐U3O8 at 773 K

Abstract

AbstractTo acquire production uranium and uranium‐iron alloys, a mix‐reduction of a direct electrochemical reduction and Li co‐deposition with triuranium octaoxide (U3O8) in molten LiCl‐KCl salt was investigated by a sequence of electrochemical experiments using cyclic voltammetry (CV), square wave voltammetry (SWV), open circuit chronopotentiometry (OCP) and chronopotentiometry (CP). The electrochemical curves on molybdenum electrode reveal that the reduction of U3O8 on the surface of cathode is a two‐step process and the reduction potential of U3O8 to UO2 is −1.70 V, and of UO2 to U is −2.45 V. The electrochemical curves on the stainless‐steel electrode, or with FeCl3 additive, demonstrate that different U−Fe alloys are generated as Fe2U and FeU6 at −0.90 V and −1.20 V, respectively. Our study proves the feasibility of mix‐reduction to prepare U metal in LiCl−KCl−U3O8 melts at −2.60 V for 480 min, and only FeU6 alloy forms in LiCl−KCl−U3O8−FeCl3 melts at −2.60 V for 480 min on the molybdenum cathode, respectively. Electrolysate U and FeU6 are proved by XRD, and SEM‐EDS analysis confirms more negative potential −3.20 V for 4 h on 304 stainless steel cathode accelerates the formation of the U−Fe phase with obvious Li co‐deposition.