Abstract
Small Modular Reactors (SMRs) are becoming one of the key trends in the development of nuclear technology, offering a flexible, safe and cost-effective alternative to large nuclear power plants. This review defines the “driving force” of SMRs as their ability to enhance safety, modular scalability, and fuel sustainability through innovative design and policy integration. It aims to provide a systematic assessment of technological trends, deployment strategies, and fuel innovations that underpin the future of nuclear energy. This article provides a comprehensive overview of the main classes of SMRs, categorised by fuel type and application, ranging from Low-Enriched Uranium (LEU) and High-Assay Low-Enriched Uranium (HALEU) reactors to thorium-232, metallic fuel and reprocessed nuclear materials. The key technical advantages of SMRs are discussed—passive safety systems, extended fuel cycles (longer operational periods before refuelling compared to conventional reactors), modular production and compactness—which make such reactors particularly suitable for use in hard-to-reach regions, military facilities, in space and as part of hybrid power systems. Special attention is paid to the prospects of advanced fuel cycles, including the conversion of thorium to uranium-233 and the reuse of actinides, which contributes to waste reduction and supports the realisation of a closed nuclear cycle. The current status of SMR projects around the world is also analysed, highlighting the most promising solutions and discussing regulatory, infrastructure readiness and geopolitical factors.