Cycle chemistry and its effect on materials in a supercritical water-cooled reactor: A synthesis of current understanding

Interest in materials degradation in supercritical water (SCW) increased significantly after the Generation IV International Forum selected the supercritical water-cooled reactor as one of six concepts for investigation. While a significant body of literature now exists on alloy corrosion in SCW, most studies have focused on the metal side of the metal–water interface. Using new data and a selective review of corrosion in SCW, this paper highlights how changes in SCW density change the corrosion mechanism, and highlights the close link between corrosion in SCW and high-temperature steam above 500 °C. Key issues in test methodologies are also discussed.

► Steel corrosion in supercritical water was studied versus temperature and density. ► A simple model invoking electrochemical and chemical oxidation was developed. ► A change in corrosion mechanism occurs above a density of ∼100 kg/m3. ► Weight change is not a reliable measure of corrosion in supercritical water. ► Above 500 °C, low pressure steam is a surrogate for 25 MPa supercritical water.