Rod bundle thermalhydraulics mixing phenomena: 3D analysis with cathare 3 of ROSA-2/LSTFexperiment

Abstract

International audienceCATHARE-3 is the new version of the French thermal-hydraulic code for the safety analysis of nuclear reactors [1]. There is a three-dimensional (3-D) module in CATHARE-3 mainly used to model the reactor vessel (specially the core). This 3-D module is based on the "porous" medium approach with two-fluid six equations model. Therefore, one set of mass, momentum and energy balance equations is written for each phase. These equations are established using a double-averaged method: first, a time-average to filter the pseudo-random variations of the flow variables due to turbulence and two-phase intermittence, and then, space-average to account for the interactions of the flow with the internal solid structures. This is illustrated by the figure and the equation bellow. Optional terms can be added in momentum and energy balance equations to model turbulent diffusion and dispersion effects. These terms have an impact on core simulation at subchannel scale. So, the CATHARE team had established models for these terms in rod bundle geometry and had validated them on various rod bundle experiments [2]