The report presents the results of the studies carried out on a concept of sodium-cooled SMR (Small Modular Reactor) CADOR (Core with Amplified DOppleR effect). Initially, a pre-design of the primary loop was performed, with a particular focus on the pressure drops along the different components of the circuit in nominal conditions. The VBA-based tool COPERNIC was used in order to conduct parametric studies and find the design that would better fit the chosen requirements. For this purpose, the number of primary loops, the primary piping diameter and the thermal power of the reactor were varied, and, through thermohydraulic modelling, the effect on the loop pressure drops and primary fluid velocity were observed.