Spectroelectrochemical Study of Uranium and Neptunium in LiCl-KCl Eutectic Melt

Experimental set up for spectroelectrochemical measurements was designed. Uranium(III) ions, UCl6 3-, are formed during anodic dissolution of metallic uranium and prolonged contact of U(IV)- containing melts with uranium metal. UCl4 dissolution in 3LiCl- 2KCl melt leads to the formation of UCl6 2- ions. They undergo a two-step electrochemical reduction: U4+→U3+ recharge followed by U deposition. Neptunium(IV) chloride dissolves in 3LiCl-2KCl melt producing NpCl6 2- ions. Electrochemical reduction of Np(IV) on a glassy carbon electrode results in the formation of NpCl6 3- ions and then leads to the deposition of neptunium metal. Electronic absorption spectra of uranium (III, IV, V and VI) and neptunium (III and IV) species in 3LiCl-2KCl eutectic were measured at 450 oC.