An investigation on the pressure losses of two different candidate rod bundles, respectively for the projects EFIT (European Facility for Industrial Transmutation) and ELSY (European Lead-cooled SYstem), has been carried out and is presented in this report. For the EFIT design a hexagonal arrangement and far the ELSY design a square arrangement of the bundle have been retained, respectively. In both cases, the bundle is cooled by lead, or lead-bismuth alloy. Four correlations available in the literature have been taken into consideration. In addition, as the rods are not wire-wrapped and the channels they delimit might be assimilated to a straight fluid passage, all results of the previous correlations have been compared with those of the Blasius model far smooth circular tubes. Results of all attempts are very similar.