Air ingress analysis of chimney effect in the 200Â MWe pebble-bed modular high temperature gas-cooled reactor

The results indicate that, due to the high flow resistance of the pebble-bed core, the air ingress flow rate is limited. The oxygen content in the reactor cavity is also limited due to the design of the Ventilated Low Pressure Containment (VLPC) that prevents the corrosion of the fuel elements and reflectors by limiting the amount of air that can enter the vessel. The results also indicate that the injection of the nitrogen in a suitable location and with a suitable mass flow rate can effectively prevent significant corrosion of the graphite.