Molten Salt Pump Journal-Bearings Dynamic Characteristics Under Hydrodynamic Lubrication Conditions

A reliable high-temperature molten salt pump is critical for the development of Fluoride-salt-cooled High-temperature Reactors (FHRs). By supporting the rotating journal, the suitable journal bearing can ensure that the high-temperature molten salt pump runs smoothly and efficiently in the high-temperature fluoride salt over a long period of time. However, many bearing candidates served well for only a short period and experienced several issues. Moreover, the molten salt pump journal misalignment or not is a key factor for the molten salt pump's long-term steady running. In the long-term operation, a misalignment in the journal bearing can result in vibrations and excessive wear on the bearing surface of the molten salt pump. The journal bearing dynamic characteristics is a meaningful sign to accurately assess the journal misalignment. Therefore, it is necessary to investigate the detailed journal bearing dynamic behavior under the high-temperature hydrodynamic fluoride salt lubrication conditions for FHR applications. This study's small amplitude vibration is superimposed on a steady-running journal bearing condition. A FORTRAN 90 program has been written for the journal bearing dynamic behavior analysis. The numerical results are validated with experimental data from the literature. The validated program was employed to predict the dynamic coefficients of high-temperature fluoride salt hydrodynamic lubricated journal bearing various Sommerfeld numbers. This study evaluating the journal bearing dynamic coefficients for molten salt pumps provides guidelines that are helpful for designing molten salt primary pumps.