Reference electrodes behavior in the monitoring of corrosion potential at high temperature

A fundamental difficulty, on electrochemical potential (ECP) measurements, arises in the development of high temperature reference electrode. The requirements, to get reliable data with a reference electrode, are chemical stability, potential independent of the environment, and calculability electrode potential on a thermodynamic scale (SHE). In this study, three types of high temperature reference electrodes have been developed for the use in a BWR type reactor work operating conditions. The reference electrodes were cooper/cooper (I) oxide with Yttria-Stabilized Zirconia (YSZ) membrane; a silver/silver chloride couple and Platinum. The application to corrosion potential monitoring is illustrated with several examples of measurements at different types environments. Such measurements were needed for studying the thermodynamics behavior and stability of these sensors and for determining the correlations between corrosion potential and water chemistry. (authors). 2 figs., 6 refs