In the literature, a macroscopic two-equation turbulence model is proposed for analyzing turbulent flows through porous media of particular morphologies (arrays of square or circular rods, packed spheres). This model has been adapted to longitudinal flows in channels, pipes and rod bundles, in order to be able to analyze turbulent flows within nuclear power reactor circuits and core using a macroscopic turbulence model. The additional source terms of the macroscopic k-epsilon equations, which appear as an output of the volume-averaging process, are modeled using the kinetic energy balance and physical considerations. The two unknown constants of the closure expression are determined from the spatial averaging of microscopic k-epsilon computations and from numerical and experimental results available in the literature. This present model has been first successfully evaluated in various simple geometries such as channel and pipe. Good agreement was also obtained between this present model and an experiment of decreasing turbulence inside a rod bundle. (c) 2006 Elsevier Ltd. All rights reserved.