Comparison and mechanism research of corrosion behavior of materials used in supercritical water-cooled reactors

• Published in: The Journal of supercritical fluids 2024-05, Vol.207, p.106192, Article 106192
• Main Authors: Deng, Zhongyue, Yang, Pu, Huo, Zhiyuan, Zou, Lin, Wang, Yueshe
• Format: Article
• Language: English
• Subjects: Corrosion mechanism; Nuclear reactor materials; Oxide layer; Stainless steels; Supercritical water-cooled reactors
• ISSN: 0896-8446; 1872-8162
• DOI: 10.1016/j.supflu.2024.106192

In this study, the corrosion characteristics of essential materials used in supercritical water-cooled reactors (SCWRs) were investigated. Austenitic stainless steels 304 SS and 316 SS and nickel-based alloys 625 and 800 were exposed to supercritical water (SCW) at 500 °C and 25 MPa. The results showed that 304 SS, 316 SS, and Alloy 800 formed a double oxide layer, with the outer and inner layers enriched in Fe and Cr/Ni, respectively. Alloy 625 formed outer Ni-rich oxides (mainly NiO) and inner Cr-rich oxides and Ni-Cr oxides (mainly Cr2O3 and NiCr2O4, respectively). The results indicated that the difference in the protective performance of the corrosion products was mainly due to the Cr content, and the order of corrosion resistance was Alloy 625 > Alloy 800 > 304 SS > 316 SS. In addition, a corrosion mechanism model was established, which lays a good foundation for corrosion prediction and protection in SCWRs. [Display omitted] •304 SS, 316 SS, Alloy 625 and Alloy 800 formed different double corrosive oxides.•The Cr-poor zones were more prone to develop into the corrosion islands.•Holes and pits in Alloy 625 were mainly related to the precipitation of Nb-rich and Ti-rich phases.•A continuous Cr-rich oxide layer provided excellent protection for the matrix material.