Book Description

In the scheme of French ASTRID (Advanced Sodium Technological Reactor for Industrial Demonstration) project, fluid-structure interaction phenomena involved in the dynamic behaviour of core flowering, which could happen during seismic events, are of high interest. Also core flowering behaviour is considered as the main initiating event for the four SCRAMs that happened in Phénix reactor during 1989 and 1990. In objective to improve the knowledge of fluid-structure interaction phenomena of dynamic issues in a SFR core, especially focused on damping, this Ph.D. thesis have been conducted in experimental, numerical and analytical approaches based on free-vibration experiments on mono-assembly test facility PISE-1A and multi-assembly test facility PISE-2C. Two series of free-vibration experiments have been performed on PISE-1A with different water heights and different mass fractions of water-glycerol mixtures to examine the dynamic behaviours with respect to different added mass, different densities and viscosities. Corresponding numerical interpretations have been conducted with 3D Navier-Stokes model in CAST3M code. Sources of uncertainties are discussed to explain the discrepancies between the numerical computation and experimental results. Edge effects are not found to have an important impact on the dynamic behaviours of the system. On PISE-2C, free-vibration experiments with different modes of excitations have been conducted, including total flowering, partial flowering with internal crown excited and partial flowering with external crown excited. A reticulate model with homogenised linear hypothesis has been developed to interpret PISE-2C experiments. Good symmetries are found in PISE-2C suggesting that the deterministic tool is valid for the analysis.