Investigating of the Effect of Air-Formed Surface Films on Copper Corrosion Properties

Abstract

Canada’s plan for the safe and long-term management of used nuclear fuel involves utilizing an engineered multi-barrier system that will be deposited in a deep geological repository (DGR).1 Developed and proposed by the Nuclear Waste Management Organization (NWMO), the used fuel bundles will be placed in carbon-steel containers that will be coated with a about 3-mm thick corrosion resistant copper (Cu) coating. To date, Cu corrosion studies have been performed on freshly polished metal coupons that have undergone a rigorous cleaning procedure to eliminate air-formed organic and oxide films from the material’s surface. However, prior to emplacement in a DGR, the containers will be fabricated and stored for periods of time where such surface films can deposit and accumulate.2 Furthermore, a standardized surface preparation/finish procedure has yet to be determined. The influence of air-formed surface films on the Cu coating’s atmospheric and aqueous corrosion behaviour is important to understand the likelihood and extent of localized corrosion under anticipated DGR conditions. This work aims to investigate the effect of aging period, surface roughness, and storage environment on the surface film’s chemical composition, morphology, and influence on Cu corrosion properties using a suite of surface analytical and electrochemical methods. The results will assist in the future development of a surface preparation strategy of the Cu coatings prior to used fuel confinement and DGR deposition. Hall, D. S., Behazin, M., Jeffrey Binns, W. & Keech, P. G. An evaluation of corrosion processes affecting copper-coated nuclear waste containers in a deep geological repository. Prog. Mater. Sci. 118, 100766 (2021).Gateman, S. M. et al. Corrosion of One-Step Superhydrophobic Stainless-Steel Thermal Spray Coatings. ACS Appl. Mater. Interfaces 12, 1523–1532 (2020).