Progress in corrosion resistant materials for supercritical water reactors

Supercritical water reactors (SCWRs) are a kind of high-temperature, high-pressure water-cooled reactors that operate above the thermodynamic critical point of water (374 °C, 22.1 MPa). Corrosion and degradation of materials used in supercritical water environments are determined by several environment- and material-dependent factors. In particular, irradiation-induced changes in microstructure and microchemistry are major concerns in a nuclear reactor. Many structural materials including alloys and ceramics have been proposed for use as SCWR components or materials for applying protective coatings in SCWRs. Various surface modification processes are also explored to change the chemical composition and microstructure of the near surface regions. This article aims to provide an overview of recent materials developments for supercritical water reactors focusing mainly on the nuclear reactor applications. The emphasis is placed on the corrosion and degradation mechanisms and the selection criteria of materials. In addition, the development of new processes for surface modification of materials in SCWRs is also briefly reviewed. Finally, some perspectives on the direction of future research in this area are also outlined.