A pilot study on modification of containment dome surface to enhance condensation

Abstract

When a loss-of-coolant accident occurs, a large amount of vapor with high temperature and pressure is generated/blow down inside the containment. The vapor is condensed via equipment such as containment spray and on the surface of the containment so that the peaks of pressure and temperature are limited less than the design pressure and temperature of the containment. This article proposed to place prickles on the surface of the containment dome to enhance the condensation and discussed the influence of the shape of the prickles on condensation. Two shapes of prickles—spherical and conical—were studied. Their performance was compared to that of a flat surface. Three-dimensional models were established and computed using the Species Transport Model and the Eulerian Wall Film (EWF) Model in ANSYS Fluent 19.2. The computational setting was validated using the COPAIN experiment. Two inlet directions—parallel and perpendicular to the surface with condensation (the Surface)—were considered to discuss the condensation performance of three different cases from the perspectives of the boundary layers of velocity and temperature, non-condensable gas layer, heat flux and film thickness. The preliminary results show that the prickle enhances condensation by increasing the surface area and perturbing the boundary layers and the non-condensable gas layer, so that the total amount of condensate increases, and most condensate is concentrated on the prickle which is conducive to the dripping of droplets. Compared with the flat surface, the total heat transfer rate of the Surface with a spherical prickle is increased by 11.7% and 5.3% with the vapor-air mixture flowing parallel and perpendicular to the Surface, respectively. Compared with the flat surface, the total heat transfer rate of the Surface with a conical prickle is increased by 5.3% and 1.3% with the vapor-air mixture flowing parallel and perpendicular to the Surface, respectively. The computational results suggest that the spherical prickle has a better heat transfer performance than the conical one. The proposed modification has the potential to be applied to nuclear power plants to enhance passive safety.