Analysis of Reactor Coolant Pump Thrust Bearing Modification of an HPR1000 Unit

The abnormal thrust bearing abrasion was found during the small flow test of the reactor coolant pump (RCP) of three-bearing structure design for an HPR1000 unit. After analyzing the RCP thrust bearing structure, the authors identify and analyze all the possible causes for this abrasion in the root cause analysis method based on fishbone diagram. According to the identification and analysis results, the authors proposing such modifications as using the oil supply of multi-nozzle design, adding oil suction chamfer at the oil film suction ports of the main and auxiliary thrust bearings, adding jacking oil structure design for reverse auxiliary thrust bearing to the original jacking oil design, build an integrated measurement system for thrust bearing temperature-oil temperature, and supporting the structure by spring plate actively compensated thrust bearing. As verified by tests, the improved RCP thrust bearing system helps enhance significantly the RCP operation reliability and inherent safety of the HPR1000 unit.