AMF #07 - The Nuclear Option: How It Can Help Shipping Meet Decarbonization Targets

1. Introduction

In a world increasingly focused on combatting climate change, the maritime industry faces mounting pressure to reduce its carbon footprint. While exploring alternative fuels as potential solutions, the challenges of implementing them in shipping have become evident.

According to the International Maritime Organization (IMO), shipping contributes to roughly 3% of the world's annual Greenhouse Gas (GHG) emissions. This compels us to explore low-carbon solutions for industry. This article seeks to address the question of whether ships equipped with nuclear propulsion systems can play a significant role. We will evaluate the advantages and disadvantages of incorporating nuclear power into ships, drawing insights from a thorough examination of existing literature and data analysis. Furthermore, we will shed light on the potential hurdles and limitations when it comes to adopting nuclear power in the maritime context.

After all, nuclear-powered naval vessels, submarines, and icebreakers have demonstrated their effectiveness. The joint model developed by the IMO and the UN Intergovernmental Panel on Climate Change (IPCC) for achieving low-carbon shipping by 2050 has identified nuclear propulsion as a "green" energy source, alongside renewable energy, and biofuels.

2. What is Nuclear Propulsion?

Nuclear propulsion involves the use of a nuclear reactor, a device that initiates and controls a continuous nuclear chain reaction. It can be categorized based on factors like the coolant it employs, technology generation, the type of reaction, the fuel used, and other variables. In the context of marine applications, most current nuclear reactors operate through a fission reaction with uranium as the primary fuel source. In this self-sustaining chain reaction, the generated heat is harnessed to superheat water, creating steam. This steam is then utilized in a common Rankine cycle with a steam turbine for propulsion or electricity generation.

The majority of marine reactors in operation today fall under the classification of pressurized water reactors (PWRs), which are also commonly used in civilian electricity generation. These PWRs are a type of light water reactor (LWR) that employs water as a coolant to manage the heat generated by the reaction. This reactor type functions in the thermal neutron spectrum and utilizes water as a coolant, coupled with a steam turbine system for energy conversion. By using highly enriched uranium, it's possible to create a more compact reactor design (with uranium-235 enrichments as high as 93%).

Additionally, advanced reactor designs can use different coolants such as liquid metals, gases, or salts, instead of water. Small modular reactors (SMRs) represent these advanced designs, offering flexibility in coolant selection (including water, liquid metal, gas, or molten salt). SMRs are known for their relatively compact physical footprint, generation capacities ranging from tens to hundreds of megawatts, reduced capital investments, suitability for locations unsuitable for larger nuclear plants, and the capacity for incremental power additions. To put this in perspective, commercial ocean-going vessel would likely require a main propulsion engine generating a range from 10 to 80 megawatts of power, hence SMRs can be suitable option for such applications.

3.?Nuclear Power in Shipping

Historically, nuclear power has found its primary application in naval vessels, particularly in nuclear submarines and aircraft carriers. Since the introduction of the first nuclear-powered ship, the American submarine Nautilus, in 1955, nearly 700 nuclear reactors have been deployed on ships and submarines. Presently, a total of 160 ships, equipped with 200 reactors, are in active service. The majority of these marine nuclear reactors have been utilized in naval surface ships and submarines. Russia, in particular, has constructed nuclear-powered icebreakers, some of which are still in operation, with plans for additional icebreakers, as outlined in Table 1.

While experimental merchant ships with nuclear propulsion have been limited in number, notable examples include the US's NS Savannah, Germany's Otto Hahn, Japan's Mutsu, and the Russian merchant ship Sevmorput, which remains in operation along with certain icebreakers.

In recent years, as the drive for maritime decarbonization has gained significant traction worldwide, numerous maritime related companies have initiated efforts to promote the integration of nuclear energy into merchant ship propulsion systems. Multiple projects and initiatives have emerged, aimed at advancing nuclear reactor technologies for application in merchant ship propulsion.

4.?The Advantages of Nuclear Energy

Numerous studies have underscored the potential of nuclear energy as a significant and sustainable energy source for propelling ships. These studies have thoroughly explored the advantages and practicality of employing nuclear energy in the propulsion of merchant vessels, with one critical finding being that "nuclear fission involves no chemical reactions." This characteristic allows for ship propulsion with zero greenhouse gas (GHG) emissions on a "tank to wake" (TtW) basis. While emissions do arise from the mining and processing of nuclear reactor fuel, the overall life cycle emissions of small modular reactors are estimated to be comparable to renewable sources like wind and solar.

From an economic standpoint, nuclear power offers ships the ability to operate for extended periods, typically 5 to 10 years, without the need for refueling. This extended autonomy shields them from the volatility of fuel prices, presenting a substantial long-term cost-effective advantage. In a discussion with a reputable UK-based manufacturer, it was revealed that the costs involved might include approximately $200 million for the reactor and an additional $300 million to secure enough fuel for 25-30 years of operation, with minor maintenance expenses on top. In contrast, a 20,000 TEU container ship consuming 250 metric tons of fuel per day and sailing for 300 days annually would consume approximately $1.2 billion worth of fuel oil over a 25-year commercial lifespan, based on today's very-low-sulfur fuel oil (VLSFO) prices.

Furthermore, it was noted in the same interview that this technology could lead to space savings, resulting in increased cargo capacity and profitability. For example, a Capesize bulker equipped with a nuclear reactor could potentially save about 4.5% of space compared to conventional fuel storage tanks and piping systems.

5.?Challenges and Concerns

While the use of nuclear energy to propel merchant ships offers substantial benefits in terms of power generation and emissions reduction, it raises several unique concerns in the context of the marine environment.

Questions regarding the legal framework within which these ships would operate and how it might differ from conventionally powered vessels are paramount.

Several key questions demand attention when contemplating the use of nuclear energy in ships:

• Disposal of waste fuel and environmental protection are pressing concerns.
• Crew training, qualifications, and associated costs are essential considerations for ship owners and operators.
• Port access terms and locations require careful assessment.
• Defining operators' liability in case of accidents, regardless of the cause, is crucial.

Studies have emphasized that the management of nuclear fuel waste stands as a central concern. This waste must be transferred from the ship to a storage facility, and it played a role in the opposition faced by the NS Savannah from local communities and port authorities in the past. To address the handling of fuel waste, a dedicated nuclear servicing vessel ship was constructed to accompany the NS Savannah and remove nuclear waste. In its first year of operation, the NS Savannah discharged 115,000 gallons (428.36 tonnes) of low-level waste into the ocean. Radioactive waste is non-biodegradable, with no feasible means of removal once it enters the sea. These substances vary in their impact but are typically absorbed by marine organisms, leading to concentration as they move up the food chain, thereby affecting the growth, reproduction, and mortality of marine life.

Additionally, regular refueling or maintenance necessitates specialized docks. History reveals that conventional ports are often hesitant to accommodate nuclear ships, even when provided with all necessary permissions and security certificates. Thus, the construction of new ports for nuclear vessels may become a necessity. These ports would be situated away from human settlements and equipped with the infrastructure required to meet the needs of ships, crew, and companies.

Daily operations of nuclear-powered merchant ships introduce environmental concerns encompassing perimeter contamination and thermal pollution. These ships are not entirely free from low-level radiation release, considering them as mobile nuclear installations. The risk of low-level radiation release may lead to persistent low-dose radioactive contamination of the marine environment, resulting in increased mortality rates for fish and marine mammals. Nuclear-contaminated seawater could further affect coastal ecosystems like mangroves due to tidal action.

Another issue arises from the substantial heat energy produced by nuclear reactors on board ships. Thermal pollution stemming from nuclear vessels can impact marine flora, fauna, and ecosystems in nearby waters. Alterations in water temperature have the potential to harm marine life, modify the chemical composition of seawater, and disrupt ecological balance.

In cases of maritime accidents involving nuclear-powered merchant ships, there's a potential for nuclear disasters at sea. Situations like ship collisions, severe machinery damage, fires, or explosions can trigger nuclear leakage, causing severe harm to the marine environment, marine ecosystems, and human health. During its maiden voyage, the Mutsu, a Japanese nuclear-powered merchant ship, encountered a nuclear leakage issue, prompting strong opposition from local inhabitants, port authorities, and fishermen.

In terms of the nuclear liability regime, strict rules apply to operators of nuclear reactor plants. Transitioning from land-based installations to sea-based operations can present challenges, especially given the absolute liability principle of the operators. This principle may not align with the management and operation of nuclear-powered ships, which are not exclusively managed by their operators. In the realm of nuclear shipping, both managers and owners can bear responsibility for ship management, and the absolute liability of the operators can absolve ship owners from certain liabilities.

6.?Social, Political and Regulatory Considerations

When contemplating the potential utilization of nuclear power in maritime applications, a holistic comprehension of the social, political, and regulatory dimensions is paramount. These discussions often commence with a broader conversation about nuclear energy, necessitating contemplation of both its benefits and concerns, not only within the maritime sector but also in the context of the global energy landscape and environmental sustainability.

Furthermore, the establishment of a robust nuclear infrastructure serves as a foundation. This encompasses fuel production, secure refueling procedures, careful planning for vessel decommissioning, and the safe disposal of radioactive waste. Stringent adherence to national requirements is essential for reactor builders, covering a wide range of considerations, from material quality to export control laws. Shipyards must develop a parallel set of requirements based on national regulations, including protocols for safeguarding nuclear devices during their storage and handling on-site, alongside comprehensive measures to protect workers from radiation exposure.

As political and technical commitment from Flag State Authorities remains central, safety assessments and regulations must be strict, even though this may lead to an extended and resource-intensive certification process. Addressing skepticism is an essential aspect; sharing safety records, emphasizing emission reductions, and highlighting robust safety protocols all contribute to instilling trust.

Licensing and compliance procedures involve multifaceted assessments and alignment with international and national regulations, underscoring the importance of collaboration with organizations like the International Atomic Energy Agency (IAEA).

Routine inspection and maintenance procedures are critical for the operation of nuclear vessels, including radiation monitoring, mechanical checks, and preventive maintenance. Regulatory approvals, as required for all ships operating internationally, involve comprehensive examinations of vessel design, safety systems, and compliance with international and national frameworks.

Presently, the "Code of Safety for Nuclear Merchant Ships" established by the International Maritime Organization (IMO) is the sole specific document outlining technical regulations for the use of nuclear power in merchant ship propulsion. This code, developed in conjunction with the IAEA as part of the Safety of Life at Sea (SOLAS) convention, primarily pertains to PWR technology, which was the prevailing choice for naval and marine purposes then. While comprehensive, the document has become outdated due to the many advancements over the last four decades.

Safety assessment standards are not only outlined in the Nuclear Ship Code and IMO Resolution A.491(XII) but also within national regulatory frameworks. These standards define risk assessments, accident scenarios, and the secure containment of nuclear materials in case of incidents.

In navigating this multifaceted landscape, comprehensive safety measures, technological advancements, and regulatory compliance all play pivotal roles in ensuring the secure and responsible use of nuclear propulsion in the maritime industry.

7.?Nuclear-Powered Ships: A Viable Solution?

Amid the global pursuit of innovative, sustainable transportation solutions with low carbon footprints, nuclear-powered ships have re-emerged as a focal point of interest. In recent times, what was once a futuristic concept has transformed into a topic of robust exploration and investment. The pressing question is whether nuclear propulsion can truly be a viable solution for the modern maritime industry. In seeking answers, we will delve into the latest projects, investments, and research shaping the future of nuclear-powered ships, providing insights into the path forward and the obstacles to overcome. So, is the resurgence of nuclear-powered vessels merely a notion, or is it poised to become a tangible reality? Let's embark on a journey to explore the promising developments.

• The American Bureau of Shipping (ABS) has undertaken a groundbreaking study on the application of nuclear propulsion in large ships, a concept gaining fresh attention for its carbon-neutral attributes. This study, carried out under contract from the U.S. Department of Energy, in collaboration with Hebert Engineering Corp., models the application of nuclear propulsion in two common vessel types: a 14,000 TEU Post-panamax container ship and a 157,000 deadweight tons (dwt) Suezmax tanker. With input from leading nuclear reactor developers, this study evaluates the installation of two distinct powerplant configurations on these vessel types. For the container ship, a twin-reactor, lead-cooled, 30MW fast reactor design is considered, enhancing cargo capacity and operational speed. In contrast, the Suezmax tanker explores the feasibility of installing a set of four 5MW heat-pipe microreactors, potentially increasing speed but reducing cargo capacity. Both configurations offer a fuel core life of 25 years, aligning with the typical operational life of merchant ships while achieving zero CO2 emissions.

• Korean industry leaders, including prominent shipping companies HMM and Sinokor, have joined hands to explore nuclear-powered ships. A Memorandum of Understanding (MoU) inked in February 2023 includes Gyeongju city, the Gyeongbuk Province, Korea Atomic Energy Research Institute, the Korean Research Institute of Ship & Ocean Engineering (KRISO), the Korean Register, Wooyang Shipping Co, Sinokor, H-Line, and HMM. Their collaboration aims to develop and demonstrate the use of small modular nuclear reactors for ship propulsion. The project also encompasses the investigation of marine system interfaces, propulsion technology, and hydrogen production using molten salt reactors (MSR).
• UK-based CORE POWER is independently pursuing the development of an advanced molten salt nuclear reactor using liquid fuel, a notable departure from solid fuel. These reactors involve the fusion of fuel and coolant in a liquid fuel-salt that remains liquid at high temperatures, minimizing the risk associated with coolant loss, a common challenge in conventional nuclear reactors.
• Samsung Heavy Industries, South Korea's shipbuilding giant, has partnered with the Korea Atomic Energy Research Institute to collaboratively develop molten salt reactors for marine propulsion.
• The United Kingdom enacted the Merchant Shipping (Nuclear Ships) Regulations in 2022, underlining its commitment to nuclear-powered ships.
• China has unveiled plans to build nuclear-powered ice-breaking comprehensive support ships and intends to deploy 20 floating nuclear power plants in the South China Sea by 2025.
• BWX Technologies and Crowley, a global shipping and energy supply chain company, are collaborating under a memorandum of understanding to develop a ship equipped with an onboard microreactor. This innovation could supply power to shore-based users via buoyed power cables, representing a zero-carbon energy option for defense and disaster relief.
• Prodigy Clean Energy, a Canadian commercial marine nuclear power developer, has entered into an agreement with NuScale Power to explore business opportunities for a marine-deployed power station using the NuScale Small Modular Reactor (SMR). This collaboration follows three years of cooperative efforts in conceptual design and economic assessments for floating nuclear power plants.
• RINA, a leading ship certification company based in Italy, is actively investigating the use of nuclear fuel and is engaged in a feasibility study alongside Fincantieri and a nuclear technology firm.

These global initiatives are propelling the exploration of nuclear-powered ships, marking a potential shift toward a more sustainable and low-carbon future for the maritime industry.

8.?Final Thoughts

In the realm of nuclear power, it is extensively employed in commercial land-based power applications and its utilization in maritime has been somewhat limited to naval ships. At present, there are substantial challenges linked to the current rules and laws governing nuclear power, especially in the context of marine use. Nevertheless, there is a growing interest from organizations responsible for setting standards in addressing these issues.

The concept of utilizing nuclear energy for maritime purposes holds promise, as it can reduce pollution, extend vessels' operating durations, and provide better control over fuel expenses. Nevertheless, challenges exist, , including how the public perceives these endeavors, the need for clear and comprehensive regulations and the safe handling of used nuclear fuel. Striking a balance between progress and safety is considered of utmost importance. These are all vital considerations for potential future applications in this field.

Looking forward, more research and collaboration are deemed essential. While several significant projects and advancements have illuminated the potential of nuclear propulsion, there remains a requirement for comprehensive, interdisciplinary investigations to address remaining uncertainties and facilitate practical implementation. Vital aspects for forthcoming studies encompass the long-term safety and environmental impacts of nuclear-powered vessels, as well as the development of safer, more compact, and versatile reactor technologies.

As countries and organizations across the globe continue to invest in research and development, nuclear propulsion may gain more interest to achieve the decarbonizations goals. It has the potential to provide the maritime industry with a sustainable, low-carbon solution for meeting the evolving demands of modern shipping. Despite the challenges, this journey toward nuclear-powered ships underscores the capacity to utilize advanced technologies in the pursuit of a cleaner and more efficient maritime future.

Disclaimer: The opinions and views expressed in this article are solely those of the author and do not necessarily reflect the official position or policies of ABS. This article is not endorsed by ABS and should not be construed as an official communication from the company. While the author is an employee of ABS, this article is written in a personal capacity and does not represent ABS in any official manner. The content provided herein is for informational purposes only and should not be interpreted as professional or legal advice from ABS.