Development of NDE technology to evaluate fatigue damage of steam generator tube

There have been two accidental tube failures relating to fatigue in the steam generators of PWR nuclear plants. Though the primary failure mechanism and the major causal factors leading to these events were adequately demonstrated and identified and corrective measures to prevent the occurrence of similar fatigue failure have been implemented, it still seems necessary to develop a method to non-destructively detect early fatigue damage in order to improve the integrity of steam generator tubes. JAPEIC (Japan Power Engineering and Inspection Corporation) has initiated a research project for the development of such a method. It began by making a literature survey to investigate fatigue phenomena that possibly occur in steam generator tubes, and by selecting the techniques which have potential to detect early fatigue damage in tubes that are in operation. In order to determine which technique has the most potential, it then conducted a comparative study on the techniques that were selected using interrupted fatigue test tubes. In the future, a method using the optimal technique will be developed for application to in-service inspection of steam generator tubes. This paper introduces the outline of the project and the main results that have been obtained