Experimental study on the oxidation of nuclear graphite and development of an oxidation model

The present study investigates the graphite oxidation, which is one of the most serious problems during an air-ingress accident of a high temperature gas-cooled reactor (HTGR). In our study, oxidation experiments have been performed for IG-110 graphite by gas analysis under the various temperatures and oxygen concentrations. As a result, the order of reaction (n) and activation energy (Ea) were estimated as 0.75 ± 0.146 and 218 ± 3.76 kJ/mol, respectively within a 95% confidence level. The CO/CO2 ratios were also measured and compared with Aurthur’s and Rossberg’s correlations. Most of data lie between their predictions, but for better prediction, an empirical correlation was newly developed. We measured reaction rates and analyzed them with a computational fluid dynamics (CFD) simulation by incorporating the oxidation parameters and the CO/CO2 ratio estimated here. Finally, an analytical model that includes both the chemical reaction and mass transfer was proposed and validated against experimental data.