| Abstract Scope |
Nuclear graphite is used in high temperature gas-cooled reactors owing to its thermal stability, high thermal conductivity, low thermal expansion, and neutron-moderating ability. During water vapor ingress accidents, however, graphite oxidation can induce mass loss, pore growth, and structural degradation. Oxidation rate and depth are governed by oxidant diffusion length and pore structure, which determine gas transport and reaction distribution. Sample size and geometry can also affect oxidation behaviors, but these effects are often neglected in kinetic models. This limits the accurate oxidation prediction of graphite components in different geometries. In this study, IG-110 nuclear graphite specimens with different sizes and geometries were oxidized in He/H2O atmospheres up to 1100 °C. Mass loss was used to calculate oxidation rates and activation energies, while cross-sectional observations evaluated pore evolution and oxidation depth. A kinetic model incorporating sample size correction parameters effectively described the observed oxidation discrepancies. |