Modeling interactive effects of Pb contamination, Ca2+ and Mg2+ on passivity of alloy 800 in simulated crevice chemistries at high temperature

A phenomenological model is postulated to interpret the interactive impacts of dissolved Pb contamination, Ca2+ and Mg2+ on passivity of Alloy 800 in simulated crevice chemistries at 300 °C. Passivity degradation is characterized by the retarded dehydration during passivation and increased donor density in passive film. Ca2+ and Mg2+ can cause the passivity degradation in the Pb-free chemistries but, if the Pb-contamination concentration exceeds a critical value, would reduce the detrimental effect of Pb-contamination. This behavior may be related to the extremely strong adsorption capacity of Pb contamination. Finally, the applications in the water management strategy of nuclear power plants are discussed.