Modeling Flow Characteristics of Reactor Sumps

After a postulated loss of coolant accident in a nuclear powerplant, heated water from the core is removed through the emergency reactor building floor sump, cooled, and reinjected into the core or the containment building via the spray system. Reduced scale models of reactor sumps are demonstrated to be an efficient means to assure the hydraulic performance of the emergency core cooling system is adequate for long term operation. Similitude criteria for model operation are described, considering the phenomena of interest such as free surface and submerged vortices, swirling flow in the pump suction lines, and energy losses in the flow path. Typical model scale ratios, construction techniques, instrumentation, and operating procedures are described. Test results from several typical recent studies are used to illustrate design features which are desirable and those that are undesirable.