Characteristics of corrosion products in low-pressure and high-pressure feedwater heaters in an operating pressurized water reactor

In this study, the characterization and comparison of corrosion products collected from the low-pressure and high-pressure heaters of an operating pressurized water reactor during the dry lay-up period indicated distinct differences in their composition and structure. Low-pressure and high-pressure feedwater heaters favored the formation of hematite and magnetite, respectively. Notably, Fe oxyhydroxides, such as goethite and lepidocrocite, were observed exclusively on the surface of the corrosion products formed in the high-pressure feedwater heater. Thermodynamic calculations confirmed the formation of Fe oxyhydroxides from Fe ions, indicating that Fe oxides such as magnetite can transform into Fe oxyhydroxides during the dry lay-up period under high humidity and oxygen-rich conditions. The results of this study could guide future research on mitigating corrosion in nuclear power plants, significantly improving their safety and efficiency.