Stress Analysis of the Canned Nuclear Coolant Pump Based on FSI

Abstract

The reactor coolant pump (RCP) is one of the most important components in nuclear power plants. It operated in high temperature, high-pressure, high speed and radiative environment, so a long-term security and reliable operations is required. Many internal flow analysis of RCPs was carried out, mainly foucs on steady and unsteady flow field at different operating points in RCP. The research about flow passage components, such as the blade of the RCP, is relatively few. When the RCPs operates in the nuclear power plant, the flow field lashed against the impeller of the RCP, results in a network of small cracks is found on the surface of impeller. For example, periodic vibration caused by a break in a guide vane leaded to cracking of two pieces blades of impeller in a large power plant in southwest of China, and this accident caused much economic loss. The computational method of stress due to the hydraulic reason is an important problem of the RCP. In this work, at first the CFD simulation including the case, guide vane, impeller, inlet and outlet at different operation points is studied, and the result of the pressure distribution on impeller blade is loaded on the impeller using fluid-structure interation (FSI) method. The result showed that the maximum von Mises stress appears on the trailing edge close to the impeller hub which has a large change in gradient of stress and which is prone to fatigue failure. The maximum stress on the impeller is mainly in proportion to the operating power. The maximum stress on the impeller have periodical characteristic, which is due to the number of blade of diffuser. All of these equip us with better understand of the fatigue and fracture of RCP, and it make sense to protect the fatigue damage and promote the stability of RCP.