Method Development for Quantitative Analysis of Actinides in Molten Salts

This paper describes how electrochemical techniques have been used to develop a method for high-precision, real-time quantitative measurements of the concentration of actinides, present in in molten salts as actinide chlorides, for pyrochemical process monitoring applications. Possible reasons for discrepancies between reported measurements obtained with electrochemical techniques have been investigated and a combination of methods to improve their precision has been established. The combination of methods consists of selecting a suitable electroanalytical measurement technique, experimentally verifying assumptions used in its theoretical analysis, ensuring reproducible conditions at the electrode/electrolyte interface, and using an improved method to eliminate the need to know the electrode surface area. By following the developed procedures and refining both experimental techniques and data analysis methods, precise and reproducible measurements were obtained for U and Pu in LiCl/KCl eutectic at 773 K. Preliminary results showed that cyclic voltammetry, along with a method of standard area addition, are very promising tools for in situ quantitative measurements with a degree of precision comparable to destructive analysis techniques.