Corrosion Monitoring of Carbon Steel in Non-Irradiated, Humidity-Controlled Environments Simulating Gamma-Ray Irradiation

Abstract

To evaluate the effect of oxidants, which are formed by radiolysis of water under gamma-ray irradiation, on the corrosion of a carbon steel in a humid environment, ozone was introduced as a model oxidant into humidity-controlled air at 50C in a thermo-hygrostat chamber. Corrosion monitoring of carbon steel was performed by using an Atmospheric Corrosion Monitor-type (ACM) sensor consisting of a carbon steel anode and an Ag cathode, and a Resistmetric Corrosion Monitor (RCM) sensor consisting of carbon steel sheets. The corrosion rates obtained from the outputs of the sensors were increased with the increase in relative humidity and were obviously increased with the increase in the introduced ozone concentration at each relative humidity, indicating that ozone accelerates the corrosion of the carbon steel. The effect of ozone on the corrosion acceleration is attributed to its easy reduction reaction and/or fast dissolution reaction into water compared to that of oxygen.