Comprehensive review of small modular reactor development focusing on challenges in the backend nuclear fuel cycle

A large number of small modular reactors (SMRs) are being developed worldwide. However, to avoid repeating the trial-and-error experiences that have prevented the disposal of high-level radioactive waste generated from nuclear power plants over the past 70 years, international agencies such as the IAEA and OECD/NEA emphasize the need to consider the backend nuclear fuel cycle (BNFC) from the early phases of reactor design. This study provides a comprehensive compilation of design parameters, including fuel type, enrichment, coolant, and moderator, for 141 SMRs currently under development or in operation, based on publicly available data. The unstructured design status of SMRs is also systematically reorganized using the concept of technology readiness levels. An integrated framework is proposed to address BNFC issues, consisting of five key factors (e.g., radioactive waste management, spent fuel management, decommissioning, nonproliferation and safeguards, and safety regulation). These are further detailed into 14 elements and 39 recommendations. Some reflect widely shared priorities from international and governmental organizations, while others are newly derived in this study. The proposed framework is applied to different reactor types and individual SMRs to identify technical gaps. The findings support strategic approaches to BNFC in SMR development and prioritization of future research and development.