Replacement of Bearing Journals on 2A-21 Heat Transport Pumps at the Wolsung Nuclear Generating Station

Abstract

The major details of the inspection and replacement of the bearing journals on each of the four Heat Transport (HT) Pumps at the Wolsung Nuclear Generating Station in Korea are presented in this paper. Investigation following a fracture of one of the journals in 1985 November revealed that the journal was excessively hard and this led to the suspicion that the other journals, as well as the replacement for the fractured journal, might also be excessively hard. New replacement journals of the correct hardness were obtained and sent to the Wolsung Site. In 1986 May, during a planned maintenance outage, the Heat Transport Pumps were disassembled, the journals were inspected, found to be excessively hard and were all replaced. At the same time, in order to take advantage of the disassembly, the pump to motor couplings were all refurbished to ensure proper pump shaft to motor alignment. The entire operation including rebalancing and pump reassembly required twenty-one days and was carried out by the Wolsung site maintenance personnel of the Korea Electric Power Company. Byron Jackson fabricated the replacement journals and provided technical guidance at the Site. AECL also provided technical support and the procedures and apparatus for inspection of the journals. The pumps were returned to service after the successful completion of this replacement operation which had never before been carried out on this scale at any other CANDU Nuclear Generating Station.