Prediction of stress-fatigue life on the impeller of the reactor coolant pump based on fluid-thermal-structure interaction method

The reactor coolant pump (RCP) is the core part of the first loop in nuclear power plant. It plays a crucial role on the stability and security of the nuclear reactor operation. As the only rotating equipment in the RCP, the impeller needs to run tens of thousands of cycles in the high-temperature and high-pressure coolant, which significantly affects the physical properties and reduces the fatigue life. This paper mainly studies the law of the dynamic stress on impeller of the RCP based on the fluid-thermal-structure interaction method, further predicting the stress-fatigue life of the impeller based on the Palmgren-Miner theory. The results show that the impeller is subjected to periodic alternating stress during rotation. The stress value gradually increases with the increase of the flow. The location and value of the maximum stress on the impeller at each moment are inconsistent. The highest negative correlation between the stress amplitude and the fatigue life is found, and the correlation is more than 19%. Fatigue failure first occurs at the junction between the inlet edge of the blade and the hub, and the fatigue life on the impeller is calculated to be 146.6 years. The fatigue life of the impeller is greater than the designed life, thus characterizing the impeller safe for use in nuclear power plant.