The scene is essentially the same whether you are in Rotterdam, Singapore, Shanghai, or any other major port. Massive ships stood in line, waiting and burning fuel. The emissions are clearly visible, even though the smoke isn’t always. Nearly three percent of the world’s greenhouse gas emissions come from global shipping, and the underlying issue is that no one has discovered a completely environmentally friendly method of transporting a 200,000-ton ship across the Pacific. Well, not just yet.
For this reason, it’s important to keep an eye on the covert developments that have been taking place in the field of maritime engineering in recent years. As a long-term solution for deep-sea shipping, nuclear propulsion is attracting the attention of an increasing number of researchers, classification societies, and equipment manufacturers. This isn’t fringe zeal. In late 2025, DNV, one of the most reputable names in maritime risk assessment, released a comprehensive white paper outlining the specifics of how nuclear-powered cargo ships could operate, what would need to happen to make them commercially viable, and which reactor technologies are most likely to be adopted. People don’t commission that kind of analysis on a whim.
There has been a noticeable change in the conversation. In September 2025, during London International Shipping Week, shipowners, insurers, and financiers discussed nuclear propulsion as a legitimate topic rather than as a curiosity. Real questions were being asked by people who had real money on the line. This is in contrast to a few years ago, when the concept was rejected as unfeasible after barely making it past the conference panel stage.
The introduction of fourth-generation Small Modular Reactors—compact, passively safe reactor designs that differ greatly from the enormous installations that come to mind when one hears the word “nuclear.” Blykalla’s SEALER reactor, a lead-cooled design created in Sweden, is one example. It has safety features that enable it to stay stable even in the absence of active external controls, and it is compact enough to possibly fit on a large commercial vessel. In 2025, Blykalla and ABB, a Swiss engineering firm with extensive experience in marine propulsion systems, signed a contract to investigate the possibility of modifying this kind of reactor for use in maritime applications. ABB is a large OEM that doesn’t move until it sees a genuine market emerging, not a startup chasing a concept.
In fact, the engineering case for deep-sea routes is quite strong. Batteries and alternative fuels find it difficult to provide a clean solution for the unique problem of transoceanic freight. Large, continuous energy output is required for long-distance travel. Massive storage volumes and intricate handling are necessary for hydrogen. Ammonia is corrosive and poisonous. In contrast, nuclear fuel has a very high energy density. When a ship is at sea for weeks between ports, a reactor’s ability to run for years between refueling is crucial. Nuclear power has been used in submarines for decades for a reason: it works best in situations where energy density and distance are the most difficult limitations.
Nevertheless, whether the economics will be viable on a commercial scale is still up for debate. In this regard, DNV’s analysis is truthful. According to the report, before nuclear becomes economically viable for a typical cargo operator, reactor costs must be drastically reduced through mass production, standardization, and modular design. Fuel supply, reactor maintenance, and waste management are examples of lifecycle costs that must be taken into account. Additionally, public perception is still a puzzle piece that needs to be solved. When it comes to nuclear ships docking close by, ports and coastal communities will have strong opinions that don’t always follow engineering logic.
Frameworks for regulations are still developing. National governments, flag states, the IAEA, and the International Maritime Organization all have a part to play. Although maps are not roads, DNV’s paper outlines potential regulatory paths. Even under optimistic assumptions, developing a unified, globally accepted legal framework for nuclear-powered merchant ships will take years.
Here, there is a more general pattern that is worth observing. After years of being written off as being too costly or politically complex, nuclear energy is quietly making a comeback in a number of industries, including industrial heat, data centers, and electricity grids. Though it’s coming later than others, the maritime sector is participating in this discussion. The foundation being laid now is significant, regardless of whether nuclear propulsion for deep-sea shipping becomes a true commercial category by the 2030s, as some projections suggest, or takes longer than anticipated. And that in and of itself is noteworthy in an industry that has traditionally moved slowly on anything unfamiliar.
