Studies of the Hydrodynamics of the Coolant behind Mixing Intensifier Grids of Fuel Assemblies of a PWR Reactor

This paper presents the results of studies of the coolant flow behind intensifier grids of TVS-Kvadrat fuel assemblies. To evaluate the efficiency of coolant mixing behind intensifier grids of various designs and select an optimal design for them, a number of experiments were carried out on an aerodynamic research stand with scale models of fuel assembly fragments. As an example area of research, the cells of the area of the guide channel are selected. The picture of the coolant flow consists of vector fields of tangential velocities, as well as graphic dependences of the distribution of transverse velocities. Evaluation of the efficiency of mixing the coolant by intensifier grids was carried out on the basis of an analysis of the parameters of intracell vortex formation and intercell mixing. An analysis of the spatial distribution of tangential flow velocities made it possible to study and detail the picture of the coolant flow, as well as to evaluate the efficiency of flow mixing in TVS-Kvadrat. The results of the experiments are used to justify the design of the cores of PWR reactors.