Determination of oxidation rates and volatile oxidation products for HTGR graphite matrix material exposed to steam atmospheres

•Oxidation results of matrix material at 800–1200°C under varied H2O (g) atmospheres.•Temperature is the dominant variable for oxidation rates and volatile gas production in H2O (g) atmospheres.•Matrix oxidation products shift from predominantly CO to greater relative concentrations of CO2 to CO at increased testing temperatures and/or steam atmospheres.