DAMAGE ASSESSMENT OF THE FEED PUMP 250-KHX SHELL AT NPP DUKOVANY

摘要

By capillary testing, some cracks were found on feed pump 250-KHX shells in the seal chamber area at the pump suction. From the shell (no. 85500410) after 26 years of operation, a ring with cracks has been cut out. In order to determine the causes of its damage destructive analysis were carried out in UJV Rez. Fractography and chemical analyses were studied by means of scanning electron microscopy. Base material and weld metal microstructures were evaluated by means of light optical microscopy. Striations were evident at the crack fracture surface. Metallographic evaluation indicates a poorly executed over-weld repair. In future, the over-weld repair will be replaced by a pressure plate. This evaluation was completed by computational analysis with a remedial action recommendation.