In the context of the energy transition and the low-carbon mix, controlling the performance and safety of the nuclear reactors in the fleet is an imperative that still opens up avenues for research and development with high added value. This is particularly true for the optimization of fuel elements.
Indeed, during its stay in the core of a power reactor, the fuel assembly is subjected to mechanical, thermal and hydraulic constraints. It undergoes a change in its geometry, in particular an elongation and a lateral deformation, due to the creep phenomenon linked jointly to the irradiation and the flow of water in the core. With the increase in the residence times of fuel assemblies in reactors and due to increasingly demanding conditions, the need to understand the phenomenon is necessary to improve the robustness of the design. This is in particular a problem of fluid-structure interaction where the flow plays a role in the creep behavior of the structure and where the deformation of the structure modifies the flow.
A previous study made it possible to implement an experimental device to obtain rapid creep on reduced-scale fuel assembly models. These tests were able to highlight a significant effect of the fluid inlet conditions on the creep behavior of the assemblies. The objective of the proposed thesis work is then to analyze the experimental results using simulation tools in order to understand and quantify the phenomenology of the coupling in fluid-structure interaction under creep. This analysis could lead to the realization of additional tests. Another important aspect will be the transposability of the results to real conditions. The thesis will be carried out at the IRESNE institute of the Cadarache center, in collaboration with the industrialist Framatome, bringing its operational vision in the monitoring and orientation of the research work. The proposed work therefore opens up solid perspectives at the end of the thesis both in research centers and in industrial environments.