Fluid–structure interaction modelling of a PWR fuel assembly subjected to axial flow

• Axial flow induces an added stiffness of PWR fuel assembly.
• A modelling based on leakage flow accounting for the flow in the by-pass surrounding the fuel assembly is proposed.
• Simulations are compared to experimental results.

Nuclear industry needs tools to design reactor cores in case of earthquake. A fluid–structure model simulating the response of the core to a seismic excitation has been developed. Full scale tests considering one fuel assembly are performed to identify coefficients (added mass and damping) that will be used as inputs in the models. Tests showed that the axial water flow induced an added stiffness. In the paper, an expression of the model accounting for the fluid in the fuel assembly with a porous media model and in the by-passes with a leakage flow model is developed. Numerical simulations are compared to experiments and showed good agreement.