A Decay Heat Removal System for a PWR Based on Air Cooling - 14287

The present paper describes the capability of an air cooling system (ACS) for a pressurized water reactor (PWR). The motivation of the present research is the Fukushima Severe Accident (SA) on 11 March 2011. Since any emergency cooling system using water was not available due to station blackout (SBO) and malfunctions, many engineers might understand that water cooling was not completely reliable. Therefore, an absolute decay heat removal (DHR) system would be prepared in order to prevent such an SA under the conditions of SBO. In the case of DHR system using water, water should be supplied from outside. If inside water in the containment vessel is used, a cooling system should survive. If air is used, coolant is supplied eternally. The plant behaviors during the SBO are calculated using the system code NETFLOW++ for a pressurized water reactor (PWR) with the ACS. The DHR characteristics are calculated under the conditions of the forced air circulation and also the natural air convection. As a result of the calculations, the decay heat can be removed by the ACS safely. The heat removal rate is proportional to the air flow rate. Material of the heat transfer tube is also discussed. (author)