Failure analysis on abnormal bursting of heat transfer tubes in spiral-wound heat exchanger for nuclear power plant

Abstract

A spiral-wound heat exchanger failed to work during the reliability test of nuclear power plant and abnormal bursting of the heat transfer tubes was found after disassembling inspection. To solve this problem, a series of macroscopic and microscopic analysis methods were conducted, and finite element analysis was also used to analyze the stress distribution of the failed heat transfer tube. The results indicated that the stress corrosion cracking (SCC) caused by the interaction of the tensile stress induced by inappropriate fabrication, the aggressive chloride and hot alkaline environment from the media and the susceptible austenite stainless steel materials degraded by improper surface treatment was the root cause of this failure. The failure mechanisms were discussed and the relevant countermeasures were proposed to prevent the occurrence of the similar failure again. Considering that the failure case of spiral-wound heat exchanger was reported rarely so far, the achievement of this paper would provide useful experience for the safety maintenance management of spiral-wound heat exchanger in the future.