This study focusses on the neutronic analysis of UN-FCMF based fuel assembly using Serpent and SCALE codes. It is shown in the proposed fuel assembly design has inherent safety features with respect to the fuel temperature reactivity coefficient, void reactivity coefficient, and moderator temperature reactivity coefficient. It is noted that the use of FCMF leads to a lower ratio of burnup to 235U enrichment ratio compared to the UO2/Zr fuel. | Neutronic analysis of fuel assembly design in Small-PWR using uranium mononitride fully ceramic micro-encapsulated fuel using SCALE and Serpent codes