“Development of a Supercritical CO2 Autoclave for High-Temperature Materials Testing in Advanced Nuclear Energy Systems”

Abstract This paper presents the development and commissioning of a supercritical carbon dioxide (sCO2) autoclave for high-temperature corrosion testing of structural materials under representative operating conditions. The facility is intended to support materials development and corrosion assessment for sCO2-based energy conversion systems, with particular relevance to advanced nuclear applications, including Generation IV reactors and small modular reactors (SMRs). The autoclave enables dynamic corrosion testing at elevated temperatures and pressures, with independent control and continuous monitoring of temperature, pressure, and moisture content in the sCO2 environment. The performance of the system is demonstrated through corrosion testing of high-temperature-resistant Ni-based alloys and the advanced austenitic steel Sanicro 25. The observed corrosion behavior, governed by coupled oxidation and carburization processes, is consistent with previously reported studies, validating the capability of the experimental setup. The developed autoclave allows materials to be evaluated under conditions closely approaching those expected in practical S-CO2 power cycles, providing a reliable platform for materials screening and selection for advanced nuclear energy systems.