Stress analysis and stress fatigue life prediction of RCP impeller based on fluid-thermal-solid coupling

Abstract

Due to the extreme working conditions of the reactor coolant pump (RCP), it is difficult to repair and replace the structure, so a more accurate technology is needed to analyze the dynamic characteristics of the RCP under extreme working conditions and predict the fatigue life. This paper takes the CAP1400 RCP as the research object, when analyzing the hydraulic excitation characteristics, it is found that resonance may occur when the excitation frequencies are 22fn, 28fn and 33fn, then use the unidirectional fluid-thermal-solid coupling technology to analyze the dynamic stress of the RCP, and then use nCode to calculate the stress fatigue. The results show that the fatigue form of the impeller is mainly stress fatigue, and the maximum equivalent stress value is 100.83 MPa, which appears at the junction of the suction surface of the blade and the front cover plate, and the point with the largest stress fluctuation is at the junction of the suction surface and the hub. The position with the shortest impeller life of the RCP is node 397, in the contact stress concentration area between the suction surface of the impeller blade and the hub, the damage value is 2.833 × 10-12, the cycle life value is 3.53 × 1011 times, and the continuous operation is 364.18 years, which meets the requirements of the RCP. Conforms to the safety criterion of 60 years of safe operation of the RCP.