Numerical investigations on the response of the passive containment cooling system and containment under a DELB LOCA scenario

On the basis of a conceptual passive containment cooling system design, one-dimensional codes, which can be applied to large dry concrete containment in nuclear power plants, are developed to analyze containment thermal-hydraulic characteristics under typical accident scenarios. In this paper, physical models and solution methods are introduced. Containment is geometrically modeled as a combination of a rising cylinder and a downward ring. It is assumed that the control volumes experience adiabatic conditions, except for the heat exchanger and breaks, and that there is no exchange of mass, momentum or energy between each volume in the rising channel and the corresponding volume in the downward ring at the same level. In the current research, we conservatively assume that the heat in the containment can only be transferred through the heat exchanger of a passive containment cooling system by natural circulation. Furthermore, the break is hypothetically set at the bottom center of the containment. Simultaneously, the responses of the containment are predicted by codes for the large LOCA (Loss of coolant accident) scenario. Under the same conditions, the natural circulation characteristics are also studied using the codes developed for the passive containment cooling system. The results may provide a basis for the design of a passive containment cooling system.