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

This payer presents the failure analysis of a river water circulating pump from a Nuclear Power Plant. The failed component was the upper shaft made o f martensitic stainless steel. The metallurgical analyses performed include fractography, metallography and energy dispersive spectrometry analysis. C harpy impact, tensile and hardness tests were also performed. The destructi ve examination carried out revealed that the root cause of the pump shaft f ailure was an improper thermal treatment of the material that generated a t emper embrittlement process. However, in addition, a hydrogen embrittlement process could have contributed to the failure. (C) 2001 Elsevier Science L td. All rights reserved.