Failure analysis of a river water circulating pump shaft from a NPP

摘要

This paper presents the failure analysis of a river water circulating pump from a Nuclear Power Plant. The failed component was the upper shaft made of martensitic stainless steel. The metallurgical analyses performed include fractography, metallography and energy dispersive spectrometry analysis. Charpy impact, tensile and hardness tests were also performed. The destructive examination carried out revealed that the root cause of the pump shaft failure was an improper thermal treatment of the material that generated a temper embrittlement process. However, in addition, a hydrogen embrittlement process could have contributed to the failure.