Huge AI data centers and their extreme energy damage are fueling renewed interest in nuclear energy. But it turns out that one of the most impactful uses of this atomic-age technology may not come from Three Mile Island or the American heartland. Instead, the hulls of the giant cargo ships plowing their way across the world’s oceans may be ready to meet the world’s growing energy needs.

Several shipping giants have been toying with the idea of ​​equipping future ships with smaller, more advanced nuclear reactors. Earlier this month, the US Bureau of Shipping, a global maritime classification society that sets technical standards for ships, granted a major Approval in Principle (AIP) to a South Korean consortium interested in building an advanced vessel powered by a pair of molten salt nuclear reactors. The AIP is essentially a regulatory seal of approval and is an essential step in the ship’s progression from idea to reality.

If it becomes a reality, the groups behind it believe the relatively small nuclear reactor on board could allow the vessel to travel at 25 knots (about 28 miles per hour) across the ocean, carrying up to 15,000 20-foot cargo containers. It is an important test for the technology, which supporters say could be the best way for the shipping industry to reduce its notoriously high and stubbornly persistent fossil fuel emissions.

The design of the ship and the integration of the molten salt reactor are being carried out jointly by the Korea Research Institute of Naval and Ocean Engineering (KRISO), Samsung Heavy Industries and the Korea Atomic Energy Research Institute (KAERI).

“Nuclear energy has the potential to fundamentally disrupt commercial shipping in ship design, operational range and energy economics. ABS is focused on building the technical and safety framework necessary to support that, and this AIP with KRISO and KAERI is a concrete part of that work,” ABS senior vice president and chief technology officer Patrick Ryan said in a statement.

New nuclear reactors are getting salty

Nuclear-powered ships, as a general concept, are not that new. After World War II, the United States military began using pressurized water-cooled reactors on warships and submarines. The first nuclear-powered merchant ship, the NS savanna, It was built in the late 1950s and cost approximately half a billion dollars today. Currently, the United States has a fleet of about 70 active nuclear-powered submarines. However, cargo ships powered by conventional nuclear power are much rarer, partly because the technology has not matured and because the large size of the reactors limits the space available for cargo. Only one of these nuclear cargo ships, the Russian sevmorput, It remains in service to this day, after being commissioned in 1988.

New nuclear-powered ships currently being considered, such as the massive Korean vessel, are taking a different approach. Instead of relying on old, massive, water-cooled reactors, their goal is to use a new, developing class of much smaller molten salt reactors. As the name suggests, these reactors use molten salt as a carrier for liquid nuclear fuel, rather than solid fuel rods. In practice, molten salt combines with fissile material such as uranium or thorium, creating a chain reaction. The heat generated by the process is transferred directly to the salt, which then passes through a boiler that generates steam to drive a turbine. Engineers designing the Korean ship say they plan to place the reactor near the center of the hull to minimize the impact of rough ocean waves and mitigate damage to the reactor that could occur during a potential collision. They also plan to build a strong radiation shield to protect the crew on board.

Although still in a relatively early stage of development, proponents of molten salt reactors (MSR) say they offer multiple advantages over conventional nuclear power. For starters, they use much less water since salt is used as the main coolant. This potentially reduces the amount of nuclear waste that is created and reduces intensive water demand. That water reduction could become even more important in light of notoriously thirsty AI data centers. MSRs are also, at least in theory, much safer. That’s because, as cabling notes, are basically self-regulating.

If a chain reaction occurs in the core too quickly and the reactor gets too hot, the salt should expand out of the core, which in turn should cool everything down. The escaping salt can then no longer trigger a fission reaction. The International Atomic Energy Agency describes them as passive safety features that regulate the reactor without the need for direct human intervention.

MSRs are also potentially cheaper. A previous analysis highlighted by IEEE Spectrum showed that an MSR-powered cargo ship would save around $70 million over its lifetime simply by not using heavy diesel. A separate and more recent study published in the International Journal of Naval Architecture and Ocean Engineering found that the ship designed by the Korean consortium would similarly offer “significant long-term cost advantages” over a fossil fuel-powered alternative.

The shipping industry’s race towards ecology

Still, there is a bigger elephant in the room when it comes to the shipping industry as a whole. More than safety or hypothetical fuel cost savings, proponents hope this foray into MSR-based helmets can work as a sort of silver bullet to meeting climate goals. At least for now, it seems incredibly unlikely that these ambitious goals will succeed. Even as automobiles have embraced electrification and solar and wind power have been on the rise, shipping has remained stubbornly tied to fossil fuels. The industry is estimated to consume around 350 million tonnes of fossil fuels a year, accounting for around 3 percent of the world’s total carbon emissions. A single container ship making the journey from Amsterdam to Shanghai is said to require 4,000 tonnes of fuel. And it’s not just any fuel: Cargo ships rely mainly on a cheaper, less refined diesel called heavy fuel oil, which produces much higher levels of environmentally harmful black carbon and sulfur dioxide than standard automobile gasoline.

The International Maritime Organization, the United Nations body that governs the industry, had previously set a goal of a 50 percent reduction in emissions by 2050. That already sounded wildly ambitious, and then they moved the goal even further in 2025. The new goal aims to also achieve net-zero emissions by 2050. To do this, companies are exploring battery power and alternative fuel sources such as ammonia. Some companies, like DHL, have even explored a new generation of wind-powered cargo ships, essentially a massive, modern version of sailing.

All of those options will help at the margins, but achieving a massive reduction in carbon emissions in a short period of time will require something more radical: government cooperation and commitment.

While ships powered by molten salt reactors are an interesting option, they still have a long way to go. Just this week, the U.S. Department of Energy granted Texas-based Natura Resources a nuclear safety design agreement for its experimental molten salt reactor, making it the closest to breaking ground. Meanwhile, China already has a 2-megawatt reactor in operation and others in development.

In other words, technology is advancing, but not exactly at what anyone would call breakneck speeds.

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