BONUS CONTENT from the JANUARY 2025 MT
Fission and Fusion
Making the case for nuclear power onboard commercial ships
By Harilaos Petrakakos
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Commercial shipping, a critical component of international trade, requires a major shift in the global energy landscape as environmental preservation and sustainability become increasingly crucial. The use of nuclear power, namely advanced fission and fusion technology, is a highly promising solution. Installation onboard commercial ships of new generation IV energy sources will help ensure the reliable, long-term energy supply required for a booming global economy and considerable emissions reductions.
Integrating fission or fusion power plants into the maritime sector is not only feasible. It’s necessary for the health of humanity and for future international trade. Because of the history of nuclear power, the issue remains divisive; but significant advances in safety, efficiency, and waste management have made even third generation nuclear power a viable solution.
Our purpose here is to look at why nuclear power must be the next frontier for powering commercial ships or using ships to replace power plants that use coal or LNG or other fossil fuels around the world.
Overcoming fear
The fear of nuclear power stems from historical errors more than modern technological advancements. Nuclear mishaps, such as the one at Chernobyl in April 1986—a horrific day that I recall well, as it coincided with the birth of my third child and an Olympiakos vs. PAOK football match—sparked a widespread sense of panic. The Chernobyl nuclear plant tragedy sent radioactive particles into the atmosphere, and many people, including myself, were left with the fear of an unknown peril. People were always concerned about poisoning their children as a result of radioactivity in the food, water, and air. With three young children of my own, the uncertainty and worry were very real.
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Fusion is the chemical reaction that takes place in the Sun.
The Fukushima disaster in 2011 reinforced the widespread distrust of nuclear power. When I visited Fukushima Prefecture in 2018, I saw that, for the locals, the tsunami was a far more vivid memory than the nuclear meltdown. Still, the damage was done, and nuclear power became synonymous with uncontrollable danger.
The true number of fatalities from these nuclear accidents, however, is substantially fewer than most people believe. According to studies, in the decades since Chernobyl, radiation exposure has killed fewer people than conventional energy sources such as coal and oil. Although the concern is understandable, media coverage and a lack of scientific knowledge have exacerbated the problem. To move forward, we must sever the connection between nuclear energy and fear. We must focus instead on the facts, particularly the advancements that have made nuclear power safer over time.
Fission power
Much of the public’s anxiety about fission power is due to outdated designs for pressurized water-cooled reactors. The majority of nuclear power facilities worldwide employ water-cooled reactors, which contributed to the Fukushima and Chernobyl tragedies. Molten salt reactors (MSRs), often known as next-generation or generation IV reactors, provide considerable improvements in both efficiency and safety.
In the 1950s, Oak Ridge National Laboratory experimented with MSRs. Unlike typical light-water reactors, MSRs use a liquid salt mixture as both fuel and coolant. This approach offers a variety of substantial advantages. First and foremost, there is no risk of a steam explosion, which was a key concern with prior reactor designs, because the salt operates at temperatures higher than water but at pressures lower than water. In addition, thorium, a more abundant and sustainable fuel source than uranium, may be used in molten salt reactors.
Thorium’s increased availability and decreased waste generation have prompted acclaim for its potential to alter nuclear energy. It can greatly improve the safety profile of fission reactors when used in MSRs. The reactor is fundamentally safer than traditional designs due to its self-regulating feature, which enables the reaction to slow down as the salt expands as it warms. A freeze plug at the reactor’s base melts in the event of a temperature increase, allowing the fuel to drain into safe storage containers and effectively shutting down the reactor. MSRs are among the safest fission power sources ever built, as the threat of a meltdown is eliminated.
Many experts believe that the first commercial MSRs will be operational within the next 10 years, even though there are still technological challenges to solve, particularly in lowering the corrosive properties of the molten salt. These reactors may ease the public’s long-held fears about a nuclear calamity while generating vast amounts of inexpensive power.
Fusion power
Fusion is by far the best alternative if fission is considered a step toward a sustainable future. Because it fuses (combines) rather than splits atomic nuclei, fusion power has a nearly limitless energy potential with minimal environmental impact.
Briefly told, fusion is the chemical reaction taking place in the Sun. In contrast to fission, which creates radioactive waste, fusion produces only short-lived isotopes, significantly reducing and possibly eliminating the issue of radioactive waste management.
Studies have shown that, in the decades since Chernobyl, radiation exposure has killed fewer people than conventional energy sources such as coal and oil.
Dubbed the “holy grail” of energy production, fusion power is expected to be capable of producing massive amounts of energy from very basic fuel sources like hydrogen isotopes. However, recent advancements in fusion technology, mostly from private projects such as Commonwealth Fusion Systems and the International Thermonuclear Experimental Reactor (ITER), have made the idea of fusion power more realistic. In 2022 and 2023, the Lawrence Livermore National Laboratory in California made major progress toward viable fusion power plants by demonstrating net energy gain from a fusion reaction—that is, more energy was created than was spent to initiate the reaction.
On the other hand, the ITER project is ridden with delays, possibly due to its being large and expensive.
There will be no denying the benefits of fusion when it becomes available. It produces zero or nearly zero radioactive waste, it emits no greenhouse gases, and there is no meltdown risk. In addition, the primary fusion fuels, deuterium and tritium, are widely available. Deuterium may be extracted from seawater; and tritium, while less frequent, can be generated by breeding lithium, another commonly found metal. This greatly outperforms the limitations of fossil fuels and even fission reactors by providing a consistent, long-term fuel supply for fusion reactors.
Naturally, the challenge is to convert fusion into a viable option. Despite considerable progress, further advancements in materials science, magnetic confinement, and reactor design are required to create long-term, economically viable fusion processes. However, there is growing confidence that fusion reactors will be operational within the next several decades as governments and private firms spend extensively in fusion research around the world, notably in the United States, China, and the European Union who cooperate in the ITER project and share the research results.
The recent announcement by Energy Singularity, a start-up based in Shanghai, promises to have the fusion reactor operational in 2028 at half the cost of the units that U.S.-based companies can develop. Similarly, nT-tao, based in Israel, has the technology to build a fusion reactor before 2030 at considerable savings.
Ideal for maritime
It is important to consider the possible uses of fusion and fission power sources in the maritime industry. Commercial ships handle approximately 90% of global trade, making them a vital business for the global economy. However, the International Maritime Organization estimates that shipping accounts for approximately 2.3% of global anthropogenic CO2 emissions.
Conventional propulsion systems, such as diesel engines, are becoming increasingly difficult to maintain as environmental concerns and regulatory demands rise. To meet the tough targets set by international treaties, the marine sector must reduce its carbon impact significantly. Nuclear power is a great option as it produces no emissions while providing ships with the high energy density and long-range capabilities they require.
Nuclear reactors provide unparalleled energy densities, particularly in fission systems such as MSRs. Commercial ships can run on a single MSR for years without refueling. Other clean energy sources, such as solar and wind power, are not comparable to nuclear; this is especially crucial for long-distance transit routes that demand regular and reliable energy. And liquid hydrogen, ammonia, and liquefied natural gas all have rather heavy “footprints” in terms of emissions.
The vessels that will be using nuclear reactors as propelling power will have the capability to go for months without the need to be refueled in the way that we are accustomed to with existing commercial vessels. Good examples of this capability are today’s nuclear-powered submarines and aircraft carriers.
Lower running expenditures
Despite their high capital costs, nuclear reactors offer extremely low long-term running expenditures. MSRs, and possible fusion reactors, need less maintenance and refueling than current commercial ships. Longer repair intervals and lower fuel costs indicate that the economics of marine shipping may alter dramatically.
In terms of environmental impact, nuclear power’s capacity to drastically reduce the environmental impact of the shipping industry is the fundamental reason for its acceptance. When in operation, neither fission nor fusion reactors generate carbon dioxide that contains carbon particulate matter pollutant.
Additionally, reactors can be installed onboard maritime structures such as barges and ships, which can be positioned to replace existing coal- or fossil fuel-run electrical plants. The use of such floating power plants was discussed during the early 1970s but this was discontinued when the political decision was made in the U.S. not to fund the efforts of the operational MSR using FliBe as the coolant medium.
While many of the issues that plagued previous technologies have been addressed in modern reactor designs, the safety of nuclear-powered ships is still a major concern. MSRs are ideal for usage in maritime environments due to their inherent meltdown resistance and passive safety features.
When fusion reactors reach a practical level of efficiency, there will be no runaway reactions and little radioactive waste. In both cases, nuclear power’s safety record has improved to the point where it is possible to consider employing it for marine trade.
In my view, and lately in the view of many engineers and scientists along with politicians around the world, fusion poses less risk than riding a train or an airplane.
SNAME’s T&R panel M-48 is preparing a risk analysis of the type that will be needed for vessels that carry both the reactor and the steam turbines and gen sets. For safety, we will consider the reactor as a very valuable component, while the steam plant will be treated in the usual manner. The reactor is the most expensive part—at least until full commercialization—of a ship. Therefore, during the design phase, we will protect the reactor (whether containerized or not in a protective enclosure by way of cofferdams) and will work to ensure that it can be removed to safety even in case of the ship sinking. On the other hand, the steam turbines, the generators, and the propulsion system will be treated as a steam-powered ship of the old. (For more information on the work of the M-48 panel, see “Unlocking the Potential” starting on page 9 of the January issue of SNAME’s MT magazine.)
Training
As we address safety, we are required to include in the risk analysis to be carried out, the following question: what are the skills required by the crew onboard commercial maritime power plants that can be used as floating power plants, or simply onboard ships powered by nuclear reactors? We have two distinct engine rooms that are necessary in these types of commercial ships, in the same way as those on the military ships. These are the engine room/space of the reactor and the engine room of the steam generating and power generating equipment.
Recently, a prominent player in the shipping sector, trying to understand the analysis of the new way of power in commercial shipping asked me, “Do you profess that there will be a need for steam turbine engineers onboard the ships?” Laughing, I replied, “Yes, exactly.” The engineers of the reactor will have to follow the ways and training currently undertaken by all those who are working in land-based facilities.
As the units are commercialized, there will be many schools appearing that will teach the aspiring new breed of scientists/sailors how to safely manage the reactors. This may work a little differently when we are faced with the training of the engineers for fusion reactors because, as has been indicated before, these reactors are inherently simple and safe.
In the deck department, where there will be no difference in current training procedures as we ensure that navigation and communication equipment will be identical to that used in current designs and existing ships.
Yamal is a Russian Arktika-class nuclear-powered icebreaker, entering service in 1989.
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Having solved how we train the reactor engineers and deck officers and crew, we turn to the steam turbine engineers, a role that has become obsolete with the use of diesel engines in the great majority of ships. We will need to train diesel engineers in the simplicity—but also the peculiarities—of steam turbines. There will be a switch from diesel engines to steam turbines where the second “engine room” will be manned by ship engineers in the same way as in the old days of steam-propelled ships.
Benefits and breakthroughs
The benefits of nuclear power for commercial ships are undeniable. Many of the difficulties currently confronting the maritime industry might be handled by nuclear power, which provides unrivaled energy density, lower operating costs, and zero emissions. As demand for sustainable energy sources rises and climate change worsens, fusion outperforms fission for a variety of reasons, including fuel availability, safety, and environmental impact. Additionally, fears regarding terrorists getting their hands on molten salt reactors are unfounded as the MSR uses spent radioactive material, which does not allow for bomb production.
We’ll watch with great interest the development of fusion reactors, with R&D and invested capital creating breakthroughs that we have not seen before.
Harilaos Petrakakos is director-senior surveyor at P&P Marine Consultants in Glyfada, Greece.