Advanced Nuclear Energy Pathways for a Net-Zero World: Fuel Cycles, Reactors, and Policy Readiness

This review examines the contributions of alternative nuclear fuels and advanced reactor technologies to enhancing the sustainability, safety, and resource efficiency of nuclear energy systems during the transition to a low-carbon future. A thorough synthesis of the existing literature was undertaken, with an emphasis on Thorium-based fuels, uranium-233, minor actinides, and innovative reactor configurations encompassing molten salt reactors (MSRs), small modular reactors (SMRs), and fast breeder reactors (FBRs). The investigation integrates various dimensions, including technical performance metrics, fuel cycle attributes, environmental ramifications, and pertinent global policy frameworks. MSRs exhibit thermal efficiencies exceeding 45% while incorporating online reprocessing capabilities, whereas SMRs provide advantages in modular deployment and intrinsic safety features. FBRs facilitate closed fuel cycles and the transmutation of long-lived isotopes. Lifecycle emissions consistently remain below 12-20 gCO₂e/kWh. Empirical case studies from India, China, and the United States substantiate this field's technical readiness and regulatory progress. Advanced fuel compositions and reactor systems offer a plausible trajectory toward sustainable nuclear energy. The achievement of this potential is contingent upon the evolution of contemporary regulatory frameworks, active public engagement, and adequate financial mechanisms. Integrating technology, policy, and public trust is essential to making nuclear energy a key pillar of global decarbonization.