Study on Wear Mechanism of Thrust Bearing of Nuclear Main Pump in Cooling Water Loss Condition

When the nuclear main pump is in the cooling water loss condition of the nuclear power plant, its thrust bearing loses cold source heat transfer. The temperature of the lubricating medium of the thrust bearing will be continuously increased due to the temperature rise of the bearing, which is accompanied by more complicated thermal transient conditions. When the thickness of the lubricating liquid film of the thrust bearing is seriously reduced, the contact wear of the friction pair occurrs due to the insufficient thickness of the liquid film. A nuclear main pump is disassambled and checked after a water cut-off test, and the wear pattern of the water cut-off operating conditions through lubrication is analyzed. When the station blackout (SBO) inert shutdown is carried out in the water cut-off condition, with the increasing of wear depth, the oil film thickness of the bearing decreases to the extent that it cannot operate reliably, and the loss increases. With the oil film temperature exceeding the Babbitt alloy operating limit temperature of 110-120℃, serious wear of the bearing is prone to occur. It provides a theoretical support for optimizing the bearings and improving the wear resistance of multiple SBO inert shutdowns after wear.