Semi-analytical modeling of the flow redistribution upstream from the mixing grids in a context of nuclear fuel assembly bow

Fuel assembly bow is a phenomenon that has drawn significant attention over the last decades, due to its role in several issues related nuclear core management. As result, nuclear-based electricity production stakeholders support extensive research on this topic. Recent studies agree various hydraulic forces affecting fuel assemblies their whole height constitute major cause of deformation. More specifically, lateral force acting mixing grid strongly depends coolant main flow distribution between itself and surrounding water gaps. This redistribution varies according position relatively neighbours. Often ignored, modeling gaps limelight article. In order design simple yet accurate model redistributions, we approximate space two successive grids (further called convergent-diffuser) as 1D-channel. The latter set up with suitable properties variable thickness reflects deflection assemblies. A network connecting gap adjacent (both represented by loss coefficients) built enable redistribution. Successive enhancements are proposed comply physical aspects neglected initial model. final version our semi-analytical achieved very close agreement both CFD simulations at local scale dedicated experimental results. obtained thanks mock-up made 3D-printed grids, especially designed validate approach’s trustworthiness. end, computational efficiency models upon initiate first sensitivity analysis. It aims emphasizing most influential inputs models, values best obtain description phenomena. described present article meant be included within larger, properly future full reactor core.