In-Situ Electrochemical Investigation of Pitting and Interphase Galvanic Corrosion of Duplex Stainless Steels via Scanning Electrochemical Microscopy for Dry Storage Canisters of Spent Nuclear Fuels

Abstract

Duplex stainless steel (DSS) has garnered significant attention as a potential material for dry storage canisters used in nuclear power plants due to its excellent mechanical properties and corrosion resistance. However, localized corrosion, such as pitting and galvanic corrosion, remains a critical challenge in ensuring the long-term structural integrity of DSS in these applications. Of particular concern is chloride-induced stress corrosion cracking (CISCC), which poses a significant threat to the safe and reliable storage of spent nuclear fuel in dry storage canisters. In this study, scanning electrochemical microscopy (SECM) was employed to investigate the pitting corrosion behavior of DSS. Selective etching of DSS phases allowed for the exposure of individual phases to the electrolyte, facilitating the analysis of galvanic interactions between constituent phases. The results provide insights into the fundamental electrochemical properties of DSS and its corrosion mechanisms, with a focus on the roles of phase composition and distribution. Additionally, this research highlights the applicability of SECM in real-time corrosion analysis and its potential for advancing the understanding of corrosion processes in metals and alloys. These findings contribute to the development of more robust DSS-based dry storage systems by addressing the mitigation of CISCC, thereby enhancing the safety and durability of nuclear fuel storage solutions.