Experimental study on transient performance in the coasting transition process of shutdown for reactor coolant pump

Highlights: • For the diverting guide vane, the existence of the flow distribution plate can improves the flow state in the interval where the flow is larger during the idling process, reduces the flow loss, improves the energy utilization and improves the head and efficiency obviously. • The diverting guide vane prolongs the coasting time of the half flow of the model pump, makes the pump more sufficient flow, and improves the reliability of the model pump's coasting process. - Abstract: The coasting characteristic of the reactor coolant pump is one of the important indicators for the safe operation of the nuclear power system. Coasting transition process of the reactor coolant pump under the working condition of power failure belongs to transient flow process. For most of the time of the coasting transition process, the parameters of flow rate, speed and head of reactor coolant pump are nonlinear. It is very difficult to study the changing law of coasting. This paper studies the energy conversion process in the coasting transition process of reactor coolant pump under accident conditions to build a comprehensive test bench for a hydraulic prototype and complete the external characteristic test and coasting transient process test of the reactor coolant pump. We find the results through coasting test: Diverting guide vane obviously improves the flow pattern (the various forms of fluid movement) larger flow conditions, reduces the flow loss, improves the energy utilization, improves the head and efficiency obviously, and prolongs the coasting time of the flow rate is reduced to the flow rate of the reactor coolant pump, makes the core of nuclear reactor obtain more sufficient coolant flow.