Fluid Flow and Mass Transfer in Finned Fuel Rod Assemblies of Nuclear Reactor BREST-OD-300

Fluid flow and mass transfer in models of fuel rod assemblies of nuclear reactor BREST-OD-300 are analyzed. The models consist of 37 rods spaced from each other by spiral fins. Assemblies have the same step of spacing between rods, but different height of fins and diameter of cylindrical shells. Constructions of this type are offered to be used in cores of fast fission reactors. Pre-test calculations were made. Information about flow structure, mass transfer in turbulent flow of coolant was obtained by methods of computational fluid dynamics. CFD- code STAR-CCM+ was used. According to calculations, characteristics of mass transfer depend on Froude number, pressure drop coefficient depends on Reynolds number and Froude number. It is shown that secondary convection generated by spiral fins is a dominant mechanism of mass transfer. Pressure drop coefficient increases with decreasing fin step; intensity of mass transfer increases with decreasing fin step or with fin height increase. Aerodynamic experiments using models of fuel rod assemblies were performed. Coolant axial velocity, temperature and pressure distributions in the models were obtained. Fluid flow was with Reynolds number from 3•10⁴ to 6•10⁴. Pressure drop coefficients were calculated. Data of numerical and physical experiment correspond to each other.

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