Abstract: With the continuous advancement of decarbonization in the maritime industry, especially after MEPC 80 setting the goal of achieving net-zero emissions by 2050, the application of low-carbon/zero-carbon fuels has become a major focus. The large-scale adoption of energy sources such as liquid ammonia, liquid hydrogen, green methanol, and LNG is gradually accelerating. Nuclear energy, as a clean energy source, is also of increasing interest to the maritime industry. With the development of fourth-generation small modular reactor (SMR) technology, the inherent safety attributes of reactors have been enhanced while reducing the risk of radiation leakage, making nuclear energy a possible propulsion method for large commercial vessels. Starting from the decarbonization needs of the maritime industry, the current use of nuclear energy as a marine propulsion method has been introduced with a focus on the recent technological developments of fourth-generation SMRs. It particularly analyzes their development potential as marine small reactors and proposes key factors that should be considered for their application onboard ships. It focuses on the unique application advantages of molten salt reactors (MSRs), especially thorium-based solid-fueled MSRs, for civilian ships. It also analyzes and prospects the application of SMRs in Suezmax oil tankers, ultra-large container ships, and floating power generation platforms. It can provide theoretical support and references for subsequent engineering applications of nuclear power in ships.

Key words: shipping decarbonization, nuclear power for ships, small modular reactor (SMR), marine small reactor, molten salt reactor (MSR), thorium-based fuel

摘要： 随着海事业脱碳化进程的不断发展,特别是国际海事组织海洋环境保护委员会第80次会议提出在2050年实现净零排放的目标后,液氨、液氢、绿色甲醇、液化天然气等低碳/零碳燃料成为业界热点,相关规模化应用持续加速,核能作为清洁能源之一也引起广泛关注。随着第四代小型模块化反应堆（small modular reactor,SMR）技术的发展,其在提升反应堆本质安全属性的同时,也降低了辐射泄漏的风险,使核动力成为大型商船推进方式的可行方案。该文从海事业脱碳需求出发,概述了目前船舶核动力推进方式,重点关注第四代SMR的最新技术发展,分析其作为船用小堆的发展潜力,并提出船用小堆上船应用需关注的关键因素。此外,该文还重点分析了熔盐反应堆（特别是钍基固态熔盐反应堆）在民用船舶领域独特的应用优势,并对SMR在苏伊士型油轮、超大型集装箱船和浮动供电平台上的应用进行分析和展望,以期为船舶核动力的后续工程化应用提供理论支撑和参考。

关键词: 航运脱碳, 船舶核动力, 小型模块化反应堆, 船用小堆, 熔盐反应堆, 钍基燃料