Small modular reactors (SMRs) with power levels much smaller than the currently standard 1000- to 1600-MW(electric) reactor designs have been proposed as a potential game changer for the future of nuclear power. We explore the contours of an expanded nuclear power generation capacity and the associated fuel cycles. To lay out a possible geographical distribution of nuclear capacity, we use results from an integrated assessment model used in energy and climate policy analysis. A wide variety of SMR designs with distinct characteristics are under development. To explore the impacts of these different designs, we have developed notional models for two leading SMR types and analyzed their resource requirements using results from neutronics calculations. Finally, we offer an initial assessment of the proliferation risks associated with these notional SMR designs compared to standard light water reactors (LWRs) using a Markov model. The analysis indicates that SMRs based on LWR technology (integral pressurized water reactors) have higher resource requirements as compared to gigawatt-scale reactors, while SMRs with long-lived cores have much lower resource requirements but a higher fissile content in the spent fuel they generate. These characteristics translate into increased proliferation risks unless they are offset by reactor design features or dedicated safeguards approaches.