Research on flow induced vibration characteristics of heat transfer tube plugs in nuclear power plant steam generators

When the defect of the heat transfer tubes in the steam generator of a pressurized water reactor (PWR) nuclear power plant meets the damage repair standard, plugging must be implemented to prevent the leakage of radioactive coolant materials, but plugging will inevitably affect the flow field state of the original equipment. In order to evaluate the safety of the heat transfer tube plug, this paper takes the heat pipe plugging as the research object, carries out the fluid-solid coupling numerical simulation of the steam generator heat transfer tube plugging based on ANSYS Workbench platform, and analyzes the action law of the fluid at the feedwater end of the bottom of the steam generator on the solid-liquid contact surface in the area. The research shows that the pressure around the plug near the edge of the feedwater end is easy to cause uneven pressure distribution on the pipe-fluid contact surface, thus causing flow-induced vibration of the plug. At the same time, the pressure at the inflow of the pipe is greater due to the scouring of the fluid, which is more likely to cause vibration. In addition, under the action of alternating inflow, the stress value and pressure energy borne by the bottom end of the plug are larger, while the displacement at the top end is larger, and the local stress at the inflow of the plug is the largest. Attention should be paid to the reinforcement of the plug at the inflow, increasing the stiffness of the bottom of the plug, and improving its natural frequency, to prevent it from failing due to resonance.