Fluid–structure interactions in nuclear power plants: Review of some main phenomena and analysis of the related safety aspects

Fluid–structure interactions such as fluid-induced vibrations are a source of wear and damage in nuclear power plants. Several issues linked with fluid–structure interaction phenomena have been constantly reported for a wide range of plant components. In order to understand the importance of fluid–structure related problems, the analysis of the underlying mechanisms should be combined to a discussion of the associated safety issues. This is what this article is intended to present. Some main fluid–structure related phenomena are presented, ranging from issues concerning reactor pressure vessel internals such as fuel rods/assemblies and thermal sleeves, to steam generator tube degradation. For each phenomenon, a review of the documented events is first presented, followed by the analysis of the underlying physical mechanisms and, finally, by the analysis of the associated safety concerns, that represents the main originality of this article. Beside, new numerical studies aimed at predicting the wear of thermal sleeves are presented: they rely on the CFD simulation of the core upper plenum. A dedicated analysis of the steam generator tube wear at the San Onofre nuclear power plant is proposed.