CFD investigating the air ingress accident for a HTGR simulation of graphite corrosion oxidation

Through a compressible multi-component CFD model, this paper investigates the characteristics of graphite oxidation corrosion in the HTR-10 core under the postulated accident of gas duct rupture. In this accident, air in the steam generator cavity would enter into the core after pressure equilibrium is achieved between the core and the cavity, which is also called as the air ingress accident. Oxygen in the air would react with graphite on pebble surface, subsequently resulting in oxidation corrosion and challenging fuel integrity. In this paper, characteristics of graphite oxidation corrosion during the air ingress accident can be reasonably captured, including distributions of graphite corrosion amount on the different cross-sections, time histories of local corrosion amount at the monitoring points and overall corrosion amount in the core, respectively. Based on the transient simulation results, the corrosion pattern and its corrosion rate would approach to the steady-state conditions as the accident continuously progresses. The total amount of graphite corrosion during a 3-day accident time is predicted to be about 31 kg with the predicted asymptotic corrosion rate. This predicted value is less than that from the previous work of Gao and Shi (Gao and Shi, 2002).

► A CFD model is proposed to investigate graphite oxidation corrosion in the HTR-10.
► A postulated air ingress accident is assumed in this paper.
► Air ingress flowrate is the predicted result, instead of the preset one.
► O2 would react with graphite on pebble surface, causing the graphite corrosion.
► No fuel exposure is predicted to be occurred under the air ingress accident.