Abstract: The treatment of radioactive spent resin by wet oxidation requires continuous processing of radioactive materials under strongly acidic and oxidizing conditions (dominated by hydroxyl radicals). The corrosion resistance of the reactor materials becomes a core concern in engineering applications. In this paper, the corrosion behaviors of three candidate reactor alloys, namely 316L, Incoloy 825, and Alloy 31, were systematically investigated under the wet oxidation conditions of spent resin. The corrosion degree, micromorphology, and characteristics of corrosion products of the alloys were characterized using the weight loss method combined with scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and metallographic microscopy, and the corrosion mechanism was revealed. The results demonstrate that after 168 h of exposure, the uniform corrosion rates of 316L, Alloy 31, and Incoloy 825 were 0.022, 0.001, and 2.132 mm/a, respectively, demonstrating that the former two alloys possessed markedly superior corrosion resistance to Incoloy 825. Further enhancement of corrosion performance could be achieved by increasing the contents of chromium, molybdenum, and nitrogen in the alloy matrices. On the basis of the mandatory retirement criterion of wall thickness reduction by half, the estimated service life of Incoloy 825 was less than 2 years, whereas both Alloy 31 and 316L exceeded 40 years, thereby meeting the requirements for long-term safe service. This study provides technical support for the optimization and application expansion of materials used in wet oxidation technology for radioactive waste resins.

Key words: wet-oxidation, radioactive spent resin, corrosion resistance, Incoloy 825, Alloy 31, 316L stainless steel