A thorough understanding of oxidation is important when considering the health and integrity of
graphite components in graphite reactors. For the next generation of graphite reactors, HTGRs
specifically, an unlikely air ingress has been deemed significant enough to have made its way
into the licensing applications of many international licensing bodies. While a substantial body
of literature exists on nuclear graphite oxidation in the presence of molecular oxygen and
significant efforts have been made to characterize oxidation kinetics of various grades, the value
of existing information is somewhat limited. Often, multiple competing processes, including
reaction kinetics, mass transfer, and microstructural evolution, are lumped together into a single
rate expression that limits the ability to translate this information to different conditions. This
article reviews the reaction of graphite with molecular oxygen in terms of the reaction kinetics,
gas transport, and microstructural evolution of graphite. It also presents the foundations of a
model for the graphite-molecular oxygen reaction system that is kinetically independent of
graphite grade, and is capable of describing both the bulk and local oxidation rates under a wide
range of conditions applicable to air-ingress.