Separation behavior of nickel and cobalt in a LiCl-KCl-NiCl2 molten salt by electrorefining process

Abstract

Among metal waste generated during the dismantling of a nuclear power plant, the steam generator, which is the main component of nickel alloy contaminated by Co-60, is classified as large-scale waste. Therefore, for the decontamination of cobalt in a contaminated nickel alloy, the separation behavior of nickel and cobalt in a LiCl-KCI molten salt containing NiCl2 was investigated at 550 degrees C. Cyclic voltammetry (CV) measurements were recorded for determining the electrochemical properties of Ni and Co in molten salt. As CoCl2 was added into the salt, the reduction peak of cobalt was observed. However, the oxidation peak of cobalt could not be observed owing to the dissolution of the cobalt resulting from the chemical reaction with NiCl2. The highest separation factor of Co to Ni was calculated to be 1394 when the Ni2+/Co2+ ratio was 4, which indicated that Ni and Co can be separated. Therefore, the possibility of its application in the radioactive waste of Ni alloys from a steam generator via electrorefining using molten salt technology was confirmed.