Pourbaix diagrams for chromium, aluminum and titanium extended to high-subcritical and low-supercritical conditions

The supercritical water-cooled reactor (SCWR) is a Generation IV concept that will operate with water above its thermodynamic critical point as the coolant. To aid in material selection and reactor design, Pourbaix diagrams for the alloying elements chromium, aluminum, and titanium have been developed under high-subcritical and low-supercritical conditions. The necessary thermodynamic extrapolations were performed using a revised Helgeson–Kirkham–Flowers model. The diagrams reveal the necessity to examine the transient reactor operating conditions such as start-up and shut-down to avoid active corrosion or dissolution of these elements from the alloys.

► Pourbaix diagrams for chromium, aluminum and titanium are extended to low-supercritical temperatures.
► Thermodynamic properties for titanium for use in R-HKF model are re-evaluated.
► Pourbaix diagrams reveal the need for examination of transient operating conditions.