Oxidation Behaviour of Alloys 800H, 3033 and 304 in High-Temperature Supercritical Water

The choice of materials is of great concern in the construction of Gen IV supercritical water-cooled reactors (SCWRs), particularly the fuel cladding, due to the harsh environment of elevated temperatures and pressures. Material's performance under simulated conditions must be evaluated to support proper material selection by designers. In this study, alloys 800H, 3003 and 304 were tested in SCW at 700 °C and 25 MPa for 1000 h. The results showed that only alloy 3033 experienced weight gain while weight loss was found for alloys 304 and 800H. Based on SEM/EDS and XRD analyses, spinel and Cr2O3, in addition to small amount of Fe2O3, formed on 800H surface, while predominant Cr2O3 and some spinel were present on alloy 3033. Alloy 304 showed no evidence of Cr2O3 on the surface, although some Cr-containing spinel and Fe2O3 were detected on the surface