Monitoring Corrosion and Oxidation Potentials in a Boiling Water Reactor^★ Available to Purchase

An electrochemical monitoring facility was installed in the bypass of the “A" recirculation line in the Dresden-II boiling water reactor. Potentials of stainless steel and platinum were measured with a silver/silver chloride reference electrode from cold-standby to full-power operation. Simultaneous measurements of dissolved oxygen and reactor water conductivity were obtained. The potentials responded to the primary reactor water chemistry. At cold-standby, potentials of about 0.5 V vs the standard hydrogen electrode (SHE) were measured, which were indicative of neutral water that contained about 5 ppm dissolved oxygen and some hydrogen peroxide. The reactor startup resulted in a large drop in corrosion and oxidation potential due to the increase in temperature and change in water chemistry. Initial steady-state corrosion potentials approached −0.1 V (SHE) at about 525 F (274 C). No significant changes in potential were observed when normal flow or dead-leg conditions were maintained in the bypass line. These in-reactor potentials will be used to guide ex-reactor experiments to obtain a better understanding of specific corrosion phenomena.