ELECTROCHEMICAL ANALYSIS OF ACTINIDES IN MOLTTIN SALTS

In electrochemical studies, the measured parameter (potential, current, or charge) is related to the quantity of the analyte in the solution and therefore can serve as an analytical signal for concentration measurements. The aim of this work is to develop high precision, real-time, quantitative, electroanalytical measurements of the concentrations of actinide chlorices in molten salts for monitoring pyrochemical process. Possible reasons for discrepancies found in the literature among electrochemically-measured values have been identified and methods to improve their precision have been established. Specific procedures were developed to refine both experimental techniques and data analysis methods. By following these procedures, precise and reproducible measurements were obtained for U and Pu in LiCl/KCl eutectic at 500°C. The effect of varying concentration on the method was investigated. In particular, the applicability of the techniques at high concentration of the analyte is evaluated. In addition to this, samples containing more than one analyte are considered, and the development of a modified data analysis method, required for their quantitative analysis, is described. Comparison of results obtained from improved electroanalytical measurements, and inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis, are shown and discussed. In addition to this, analysis of current-time transients, following a potential step, provide fundamental information about nucleation and growth of actinides on inert electrodes from molten salts. The effect of different concentrations of electroactive species, the applied potential, and the material of the working electrode on nucleation parameters are examined and discussed.Ph.D. in Chemical Engineering, May 201