The American Bureau of Shipping (ABS) has recently concluded a significant study on the use of nuclear propulsion in large ships, a proven concept gaining renewed interest for civilian applications due to its carbon-free nature.
Under a contract from the U.S. Department of Energy, ABS collaborated with Hebert Engineering Corp. (HEC) to model nuclear propulsion for two common vessel classes: a 14,000 TEU Post-panamax boxship and a 157,000 dwt Suezmax tanker. Working with input from leading nuclear reactor developers, the ABS-HEC team assessed the installation of two different powerplants for these vessel types.
For the boxship, the team selected a twin-reactor, lead-cooled, 30MW fast reactor design with a total installed power of 60MW (equivalent to 80,000 horsepower). This configuration was found to increase cargo capacity and operating speed for the ship. The lead-cooled fast reactor, though not used in commercial settings, has been previously employed in a maritime application by the Soviet Navy for their ultra-fast Alfa-class attack submarines, capable of speeds exceeding 40 knots underwater. The reactor design’s advantages include compactness and inherent safety, as the coolant solidifies in case of a leak or shutdown.
On the Suezmax tanker, the team explored the possibility of installing a different power setup: a set of four 5MW heat-pipe microreactors, resulting in a total installed power of 20MW (equivalent to 27,000 horsepower). While this configuration would increase the tanker’s speed, it would reduce its cargo capacity. Heat-pipe microreactors utilize a passive cooling system with long, hollow pipes containing a self-circulating heat transfer fluid. The technology, dating back to Cold War-era research for nuclear reactors in space applications, is still experimental and boasts advantages such as a smaller reactor size and fewer moving parts.
In both cases, the fuel core is expected to last for 25 years, which aligns with the typical operational life of a merchant ship, ensuring zero CO2 emissions during its lifetime.
Christopher J. Wiernicki, ABS Chairman and CEO, stated, “A net-zero world is more easily realized through nuclear propulsion, and we are laying the foundations for that future today.” He emphasized the potential of advanced or small modular reactors, which address safety concerns and efficiency while reducing costs, waste, and proliferation risks. Wiernicki, however, stressed the importance of addressing safety issues and thoroughly evaluating these technologies.
Moreover, the U.S. Department of Energy has engaged ABS to support research into the thermal-electric integration of a nuclear propulsion system on a commercial vessel, with the University of Texas conducting this research.
Although nuclear power has a longstanding history in naval applications, its potential for the maritime industry in the 1950s faced obstacles due to safety concerns and operational challenges. Despite this, Russia remains the only country operating a nuclear-powered cargo ship today, while ABS’s study opens new possibilities for the industry.