Abstract:
In order to explore the hydrodynamic characteristics of transient process of the reactor coolant pump shaft stuck accident, a full three-dimensional simplified model of the reactor primary circuit system was established by dynamically matching the hydraulic characteristics of the reactor coolant pump and the resistance characteristics of the system pipeline. The transient numerical simulation of the reactor coolant pump shaft stuck accident condition is carried out by using the computational fluid dynamics (CFD) method, and the transient variations of external characteristics, internal pressure field, impeller blade load and force of the reactor coolant pump under different shaft stuck conditions are obtained. The study shows that the shorter the shaft stuck time, the more dramatic the transient variation of the reactor coolant pump characteristic parameters, and the more serious the impact of the accident. Taking the moment when the impeller speed just drops to 0 r/min as the node, under three shaft stuck conditions (i.e. shaft stuck time = 0.1 s, 0.3 s and 0.5 s), the flow rate decreases to 82.3%, 61.4% and 49.6%, respectively, of that under the normal operation. The head of the reactor coolant pump reaches the reverse extreme value, i.e. −137.7%, −87.4% and −56.9% , respectively, of the value under the normal operation. The pressure difference between the two sides of the impeller blade reaches the maximum, i.e. 1.34 MPa, 0.73 MPa and 0.47 MPa, respectively, and a relatively concentrated low-pressure area is formed on the side of the blade working surface in the impeller blade and in the middle part of the guide vane flow channel. The reverse extreme value of the axial force on the impeller reaches −159.3%, −96.5% and −65.5%, respectively, of the value under the normal operation. The numerical prediction method provides certain data support for the dynamic safety assessment of the reactor hydrodynamic system.
