Gas production from hydrothermal and radiolytic reactions at silicon carbide-water interfaces

Abstract

The present work explored the surface reactions in SiC suspensions subjected to high temperature and 60Co-gamma irradiation, respectively. We observed for the first time the pH-dependent SiC dissolution by water at 300 °C and 10 MPa produces a substantial CH4, while the formation of another product H2 is decreased by the reaction time. On the other hand, the continuous H2 production from water radiolysis is greatly enhanced by the presence of an interface possibly due to the interfacial charge transfer processes. Both of the reactions are accelerated by the increased active surface contacts that are associated with the decreased SiC particles size from 250 nm to 50 nm and rising weight percentage from 3% up to 7%. The XPS, FTIR, SEM, and XRD data found little microstructure changes by gamma irradiation, but noticeable corrosive surface during hydrothermal reactions. The study pointed out that gas release is an important factor that should be considered when SiC is applied for LWR fuel assemble.