While small-scale nuclear power is typically thought of for niche markets, recent work has suggested that it could help address the massive gaps in energy access in developing countries. However, nuclear energy has safety, governance and economic considerations that affect its deployment. Here we present a global analysis of regions suitable for nuclear reactor deployment based on physical siting criteria, security, governance and economic competitiveness. We use high-resolution population and satellite night-time light data to identify areas in need of electricity. We show that, technically, reactors in the 1–50 MWe range could serve 70.9% of this population. However, economics alone would make microreactors uncompetitive compared with renewables and energy storage for 87% of this population. Grid extensions and small modular nuclear reactors (with more competitive economics) could electrify these populations, but governance issues could limit deployment for all but 20% of this population. Together, governance and economics eliminate 95% of the potential market for microreactors.