International Conference on Small Modular Reactors and their Applications

Progress of S-CO2 corrosion behavior of structure material in SMRs

Not scheduled

20m

Vienna

Poster Track 2: Advanced fuels, reprocessing, waste management and decommissioning aspects for SMRs – Safety, Design and Technology

Speaker

WANHUAN YANG

Description

The supercritical CO2 (S-CO2) Brayton cycle has garnered significant attention in SMRs due to its highly efficient thermoelectric conversion, compact component size, and simplified cycle layout. However, the corrosion of alloys in high-temperature S-CO2 environments poses a major challenge for the application of the S-CO2 Brayton cycle system, given its high operating temperature (up to 750°C) and long design life (over 20 years). The China Institute of Atomic Energy (CIAE) has conducted corrosion tests on crucial components, such as heat exchangers, pipes, and turbines, to assess corrosion and life degradation mechanisms in an S-CO2 environment at 500°C and 25 MPa for up to 6400 hours. This study was specifically tailored to meet the research and development needs of small reactors. The materials examined included stainless steel, nickel-based alloys, and a new material known as Malfr-32. The results indicate that Malfr-32 exhibits superior corrosion resistance compared to nickel-based alloys and stainless steel. Similar to the formation of a dense oxide protective layer on nickel-based alloys, the surface of Malfr-32 develops a unique spinel structure to inhibit further corrosion. In contrast, the Fe304 layer formed on the surface of stainless steel is porous and not suitable for long-term corrosion resistance. CIAE has introduced the groundbreaking high-speed dynamic S-CO2 corrosion test system, the first of its kind in China. This system is designed to evaluate the corrosion resistance of essential materials and components, including power generation system pipelines and heat exchangers, in the S-CO2 environment. With operational capabilities of up to 650°C, pressures of up to 30 MPa, and flow rates of up to 2650 kg/h, this test system provides a strong foundation for the comprehensive evaluation of materials and components used in small reactor S-CO2 power generation systems. Its importance is significant in driving the advancement of related engineering technologies in China.