Steel Corrosion in Supercritical Water: An Assessment of the Key Parameters

Abstract

The key variables identified to date that influence corrosion in supercritical water (SCW) are temperature, density (pressure), water chemistry (dissolved oxygen concentration, pH control additives), surface finish and irradiation. Work carried out at Chalk River Laboratories over the past few years has focussed on assessing the relative significance of these variables, excluding irradiation. In particular, the work focussed on studying those variables (e.g., density, chemistry, and surface finish) that had not been examined in detail in the supercritical water-cooled reactor (SCWR) literature. A large matrix of tests were performed using 304 stainless steel. The data suggest that surface finish can have as large an effect as temperature on the corrosion rate. The magnitudes of the effects of varying the water chemistry (including oxygen concentration and pH) and water density are similar, and smaller than those of surface finish and temperature. These results are being used to develop strategies for further, longer-term testing.