This paper presents preliminary results of neutronics and thermal-hydraulics design analysis of a sodium cooled, small modular reactor (SMR). The reactor's nominal thermal power is 150 MWth at sodium inlet and exit temperatures of 630 and 780 K. The reactor core is comprised of three rings of shrouded hexagonal assemblies of 19.8% enriched UN fuel pins and a hexagonal assembly of enriched B4C pins in the central cavity for a coarse reactivity control. The objectives are to provide enough excess reactivity for achieving a refueling cycle > 5 year, maintaining a more even coolant flow in the core assemblies and keeping the peak centerline temperature of UN fuel pins < 1300 K. Fuel assemblies with scalloped shroud walls, 4 rings and 1.942 cm diameter fuel pins with p/d = 1.098 are selected for the reference design of the present SMR. In this design, peak fuel centerline temperature is only 1240 K and the beginning-of-life, cold-clean excess reactivity is $26.67. Copyright © 2011 by ASME.