This study made an effort to design a novel high-power density SMR core based on a hexagonal lattice for the soluble boron free environment. The VVER-1000 reactor core was converted to an SMR core with a “halved scale”. The core design process is divided into two parts; Part I: assembly-level analysis and Part II: whole-core analysis. Important design parameters such as core dimensions, number, and arrangement of fuel assemblies, fuel enrichment, appropriate burnable poison, and placement of burnable poison pins have been studied in Part I. Also, by designing an optimized burnable poison pattern, the excess reactivity and acceptable radial pin power distribution were treated without soluble boron. WIMS, and PARCS codes have been investigated for fuel assembly and whole core analysis. Finding the most appropriate fuel-loading pattern involved an iterative manual optimization between the core loading pattern and FA design to assess the acceptable neutronics and thermal-hydraulics core features and satisfy the safety margins.The design of high-power density core requires accurate prediction of the thermal–hydraulic parameters to ensure safe operation. In Part II coupled 3-D neutronic/thermal–hydraulic analysis has been done to identify the main safety challenges of the developed core. To access the proper discharge burn-up, an initial enrichment of 6.6% U235 was determined for the developed core. The developed core maximum discharge burn-up is equal to ∼49 Mwd/KgU at full power operation. Radial-zoning burnable poison is investigated in the seek of a proper pattern to limit power peaking.