Study on the effect of high temperature on the seismic performance and rotor dynamic characteristics of the molten salt pump for reactor

The high-temperature molten salt pump is the crucial rotating equipment in the molten salt reactor and the first circuit’s pressure boundary. The pump belongs to safety class I equipment and seismic category I. Seismic response and rotor dynamics are essential for the stable operation of the pump, which is directly related to the entire reactor’s safety. The submerged temperature of the molten salt pump reaches as high as 700 °C, which is significantly higher than the design temperature of primary coolant pumps in pressurized water reactors. In order to investigate the effect of high temperature on the seismic performance and rotor dynamic characteristics of the molten salt pump, this study comparatively analyzed the modal characteristics, seismic response and stress, rotor critical speed, and rotational amplitude with the high-temperature effect and without high-temperature effect using thermal-vibration coupled numerical simulation. The analysis results showed that with the effect of high temperature, the molten salt pump’s first-order modal frequency has decreased by 6.2 %, the modal shape has not changed significantly, the displacement and stress under earthquake respectively have increased by 13.9 % and 9.2 %, the first-order critical speed of the rotor has decreased by 5.1 %, and the rotational amplitude has increased by 17.4 %. The primary factor of high temperature’s effect on the molten salt pump is the change of the elastic modulus, and the effect of the thermal stress is relatively minor. The research indicates that in the seismic and rotor analyses of molten salt pumps, the effect of high temperature needs to be considered; otherwise, it may cause specific safety hazards. The results of this paper can provide a valuable reference for the design and analysis of the molten salt pump for reactors and further ensure the pump’s stable operation and structural integrity.