Nuclear microreactor propulsion concept from MIT Maritime Consortium gets green light

A consortium of leaders in academia, class, shipbuilding, and shipowning has received approval in principle (AiP) for a nuclear reactor that uses a novel cooling technology in a cargo vessel’s propulsion system. The AiP was granted by ABS, which reviewed the reactor-to-machinery interface based on class requirements.

Developed by the Massachusetts Institute of Technology (MIT), HD Korea Shipbuilding & Offshore Engineering (HD KSOE), and Capital Maritime Group, this nuclear reactor design uses a special synthetic fluid to carry heat from the system’s core. Typical modern designs focus on microscale thermal outputs of 10-20 MW. The MIT design’s near-atmospheric operating pressure can allow for thinner, lighter reactor vessels, supporting modular construction and easier transport, according to ABS.

In 2025, the consortium performed a study assessing the feasibility of retrofitting a Neopanamax container ship with nuclear microreactor propulsion. The research examined the replacement of the 12,000-TEU box ship’s two-stroke, slow-speed WinGD 7X92-B diesel engine and auxiliary generators with two MIT-designed Organically Cooled Reactors (OCRs), each paired with a 27-MW Mitsubishi steam turbine generator and a Leonardo DRS 36.5-MW direct-drive electric motor.

“As the industry evaluates new pathways for the future, this approval in principle highlights the value of collaboration with key stakeholders in advancing promising commercial nuclear technologies,” said ABS Senior Vice President and CTO, Patrick Ryan. Mr Ryan called the MIT reactor design “an interesting piece of technology,” noting its characteristics “can support modular fabrication and vessel integration,” offering “one possible pathway toward the safe, practical development of next-generation commercial shipping solutions”.

HD KSOE vice president and head of Green Energy Research Laboratory, Sangmin Park, said, “Nuclear energy represents one of the most promising alternatives to traditional fossil fuels.”

“It is our responsibility as an industry to explore every potential solution, including those that challenge conventional thinking. Nuclear propulsion is one such frontier,” said Capital Clean Energy Carriers Corp, chief sustainability officer, Stergios Stergiou.

“Our reactor design is one of the first concrete outcomes of this synergy, providing a realistic pathway towards nuclear propulsion for commercial vessels,” said Themis Sapsis, Koch Professor of Marine Technology at MIT and Co-director of the Maritime Consortium.

The AiP is part of the ABS New Technology Qualification service that provides a structured approach to support the early adoption and implementation of innovative solutions.

This is the first AiP for the MIT Maritime Consortium, formed to conduct research into alternative fuels, new nuclear technologies, data-driven operational strategies, autonomy, cybersecurity, and onboard manufacturing. ABS, HD KSOE, Capital Maritime Group, and Delos Navigation are founding members.