This paper presents the results of neutronic analyses and reactivity depletion calculations for the Scalable Liquid Metal cooled small Modular (SLIMM) reactor. A companion paper introduces and describes the conceptual design of this small modular reactor (SM,) with enriched UN fuel clad in HT-9 steel cladding and all passive operation, except the control drives. Natural circulation of liquid sodium, with the aid of in-vessel helically coiled tubes Na/Na heat exchanger, cools the reactor core during nominal operation and after shutdown. This work investigates the effects of the UN fuel enrichment below 18% on the cold and hot-clean excess reactivity, while maintaining a safe shutdown margin. Also investigated are the effects of using no, depleted UN, BeO and HT-9 followers for the enriched B4C control rods in the emergency shutdown and reactor control systems and BeO walls for the hexagonal UN fuel assemblies in the driver core. The investigated reactivity worth of the HT-9 core barrel wall as a function of thickness is very small. At nominal operational temperatures, the best results are with BeO followers, UN fuel enrichment of 17.65% and BeO shrouds of the UN fuel assemblies in the driver core. Estimated operation life of the SLIMM reactor at nominal powers of 20 and 100 MWth is ∼26.8 and ∼5.6 full-power years without refueling, respectively.