Simulation of Heat and Mass Transfer in Wire-Wrapped Fuel Assemblies in the Anisotropic Porous Body Approximation

Results of the simulation of heat and mass transfer in wire-wrapped fuel assemblies in the anisotropic porous body approximation using the developed APMod software package are presented. The modifications introduced into the porous body model to make it suitable for wire-wrapped fuel assemblies are described. The predictions of thermal and hydraulic characteristics in the liquid-metal cooled experimental and model fuel assemblies according to this updated model are presented. An isothermal sodium flow in a Bundle 2A experimental 19-rod wire-wrapped assembly and uniform or nonuniform heating of the rods was studied. The predictions were compared with the experiments using the pressure difference across the assembly versus the coolant flowrate and the coolant temperature distribution in the assembly’s outlet section. The thermal–hydraulic characteristics in the BN-1200 reactor fuel assembly’s heated 19-rod fragment with its flow cross-section locally blocked in the central part calculated by the porous body model were compared with the predictions by the CONV-3D DNS code. Before their comparison, the distributions of local velocities, pressure, and temperature in an assembly cross-section calculated by the CONV-3D code were averaged over the averaging cells in the APMod software package. It is demonstrated that the APMod software package may be used to calculate parameters, which are averaged over a representative averaging cell, in a liquid-metal coolant flow in wire-wrapped fuel assemblies with an accuracy adequate for engineering applications.