Feasibility and readiness of next-generation small modular reactors for marine decarbonization: A technical, economic, and societal review

Next-generation Small Modular Reactors (SMRs) offer a transformative solution for decarbonizing maritime transport by eliminating 100% of propulsion-related greenhouse gas emissions, thereby supporting the International Maritime Organization's (IMO) net-zero target by 2050. Despite extensive research on terrestrial SMRs, their readiness for marine applications remains underexplored. This critical review assesses the feasibility and readiness of SMRs for marine propulsion and floating nuclear power plants using the Technology Readiness Level (TRL), Investment Readiness Level (IRL), and Community Readiness Level (CRL) frameworks. Compared to fossil fuels and low-carbon alternatives such as hydrogen and ammonia, SMRs provide exceptionally high energy density (on the order of 10 6 –10 7 MJ/kg) and significantly longer fuel cycles, ranging from 6 to 10 years for current HALEU-fueled designs to up to 30 years for advanced microreactors and high-temperature gas-cooled reactors. PWR-based systems demonstrate the highest technological maturity (TRL 7–9), while non-light water reactor concepts offer advantages in passive safety, thermal efficiency, and waste minimization but remain at lower readiness levels. Key challenges, including regulatory harmonization, public acceptance, high capital costs, and constraints in the HALEU and advanced fuel supply chains, are critically analyzed. Through a comprehensive evaluation of reactor designs, safety systems, infrastructure needs, and international collaboration pathways, this study identifies standardized designs, leasing models, hybrid propulsion architectures, and policy support as essential enablers. These findings provide actionable insights for shipbuilders, policymakers, investors, and regulators to advance nuclear propulsion as a credible cornerstone of zero-emission maritime transport.