RESPONSE OF ELECTROCHEMICAL SENSORS TO IONIZING-RADIATION IN HIGH-TEMPERATURE AQUEOUS ENVIRONMENTS

A high-energy electron linear accelerator (LINAC) generated intense electromagnetic bremsstrahlung that approximated the gamma dose rate in the core of a boiling water nuclear reactor (BWR). Experiments with polymer-free platinum, pH, and silver/ silver chloride electrodes at BWR operating temperatures in a stainless steel (SS) autoclave showed reversible, stable voltage offsets that depended on water chemistry and radiation intensity. These changes occurred slowly, and the potentials required several minutes to attain a steady state. Even with a remote reference, it is not possible to determine unequivocally the magnitude and direction of the shift for a specific electrode, but these measurements are most consistent with substantial (100 mV) offsets for silver/silver chloride electrodes, and relatively stable operation for zirconia-membrane pH electrodes. Radiation had no significant effect on high-temperature conductivity. Chemical interactions with radiolytic species offer the simplest explanation for the