Elucidating the Deposition Mechanisms of Corrosion Products on the Stainless Steel Piping Surface of a Pressurized Water Reactor Primary Circuit

The deposition of corrosion products in the primary circuits of pressurized water reactors (PWRs) poses a threat to the reliable operation of nuclear power plants. However, the underlying mechanisms remain unclear. In this work, density functional theory (DFT) calculations were performed to investigate the deposition process of corrosion products on the Fe–Cr–Ni alloy (111) surface at the atomic scale. The results reveal that the adsorption strength follows the order Cr > Fe > Co > Ni under solvation conditions. Electronic structure analysis shows that the adsorption strength is mainly governed by the number of d electrons, with more d electrons leading to a greater occupation of antibonding states and lower bond order. Furthermore, solvation effects could enhance the stability of the Cr and Fe adsorption. However, thermodynamic stability alone cannot account for the experimentally observed deposition behaviors. Despite the higher thermodynamic stability of Cr, hydrolysis kinetics dominates the deposition process, ultimately resulting in Fe-dominated deposition. Overall, this study provides an atomic-scale understanding of the early stages of CRUD nucleation and offers theoretical support for developing predictive models and effective mitigation strategies.