Sailing Back into the Future

Nuclear-powered commercial shipping remains years from deployment, but the sector has moved meaningfully closer to reality in the ~18 months since we published our late-2024 cover story titled Sailing into the Future. Regular Ux Weekly readers have likely seen the conversation around nuclear propulsion in the global maritime industry shift from theoretical decarbonization potential to the practical building blocks of commercialization. With evolving international rules permitting reactors to propel seagoing vessels, emerging insurance frameworks, and growing numbers of international entities advancing ship and reactor designs, nuclear shipping has moved from the margins to the starting gate.

The “why” is clear, as the International Energy Agency (IEA) estimates that international sea shipping accounts for more than 2% of global energy-related CO₂ emissions. Additionally, nuclear-powered propulsion could accelerate trans-ocean shipments by enabling higher cruising speeds while eliminating refueling constraints. Thus, it is clear why shipping companies, reactor vendors, and related stakeholders see nuclear as potentially paradigm-shifting, allowing more voyages annually and shorter transit times. Given all the activity in this space, we think it is again time to analyze where the nuclear shipping industry is heading.

Rules Coalesce

Naturally, international standards must be crafted to support nuclear’s foray into the high seas. One of the clearest signs of recent progress is that the UN’s global shipping agency, the International Maritime Organization (IMO), is moving to modernize the global rulebook for nuclear-powered ships. At a January meeting, the IMO finalized a draft workplan to update safety regulations for civil nuclear propulsion systems, with a timeline pointing to approval of a revised Nuclear Code and amendments to the SOLAS treaty, which sets minimum safety standards for ship construction, equipment, and operation, by 2030. This is a significant development, as the current framework is widely viewed as outdated and unable to support modern SAMR designs. Meanwhile, under a separate greenhouse gas emissions reduction strategy, IMO seeks to achieve net-zero emissions by or around 2050, with interim reductions of at least 20% by 2030 and 70% by 2040 versus 2008 levels. These targets are nearly impossible given the shipping sector’s current high carbon-intensity, but they underscore a compelling case for nuclear-powered vessels to achieve reductions in the future.

Bridging Frameworks

Another major development is the growing effort to bridge maritime and nuclear regulatory frameworks to support the future nuclear-powered fleet. In late 2025, global shipping technical standards agency Lloyd’s Register (LR) published a roadmap for the safe use of nuclear technology in commercial shipping and offshore applications. At the same time, the company partnered with UK nuclear shipping company Core Power and marine insurance provider NorthStandard to develop a UK-focused policy framework supporting advanced maritime nuclear. LR took the initiative a step further earlier this year, launching a Maritime Nuclear Consortium with Rolls-Royce, Babcock, and others, which collectively seeks to develop a network of certification frameworks, safeguards, and insurance pathways to support the nuclear-powered ships of tomorrow.

Looking globally, the International Atomic Energy Agency (IAEA) is advancing its ATLAS initiative, which aims to build the regulatory and technical foundation to enable SAMRs at sea. Together, these efforts show that commercializing nuclear-powered ships depends not just on reactor technology, but on aligning insurers, regulators, ports, and governments within a common framework.

Commercialization on the Horizon

Seaborne SAMRs’ overall commercial case has made some notable strides since our last update in 2024. For example, LR’s 2025 study found a 15,000-TEU (Twenty-foot Equivalent Unit) nuclear-powered containership could eliminate bunker costs, avoid carbon penalties, and increase annual cargo capacity through higher operating speeds and additional space freed by removing fuel tanks. The study estimates that just a single nuclear-powered vessel could avoid up to $50 million per year in bunker costs and roughly $18 million in carbon penalties while operating at 25 knots, up nearly 40% from the current fleet’s ~16 knots speed, allowing for more round voyages than a conventional ship, and adding 5% of additional container space to existing vessels due to the elimination of fuel tanks and systems.

LR’s report underscores that success will depend on a requirements-led supply chain and coordinated procurement through a cross-industry consortium. The analysis shows that if the industry commits to ordering more than 1,000 units over ~15 years, SAMRs could be produced at ~$750-1,000/kW, while fitting within standard vessel drydock cycles. Each unit is expected to operate for about five years between refueling, reducing downtime and limiting reliance on global bunkering networks. The study also outlines a pathway to commercial readiness within roughly four years of a high-case “focused development program,” with total system costs projected at below $4,000/kW and fuel costs under $50/MWh. LR’s modeling suggests potential deployment of 40-90 GWe by 2050, depending on regulatory progress and industry uptake. While these outcomes depend on standardized supply chains and large-scale procurement, the analysis moves beyond generalized optimism by outlining when nuclear propulsion could be commercially competitive without a green premium.

Meanwhile, on the design side, several projects are producing tangible milestones. While the list is too long to recount here, a few notable examples include South Korea’s Samsung Heavy Industries and the Korea Atomic Energy Research Institute’s (KAERI) 2025 Approval in Principle (AIP) from American Bureau of Shipping (ABS) and the Liberian Registry for a 174,000-cubic-meter LNG carrier powered by a 100 MWt MSR SAMR, which is designed to operate without refueling over the vessel’s lifetime. ABS, HD Korea Shipbuilding & Offshore Engineering, and HD Hyundai Heavy Industries added to the initiative in early 2026, launching a joint development project to assess a nuclear-powered electric propulsion system for a 16,000-TEU container ship. Meanwhile, LR granted an AiP for a hybrid nuclear-ready concept with Seatransport, combining HTR microreactors with diesel-electric systems. While none of these approvals authorize construction, they mark a clear step beyond earlier high-level feasibility studies toward more defined vessel concepts.

FNPP Pathfinders

Floating nuclear power plants (FNPPs) are becoming increasingly relevant to the shipping story, even though they do not use nuclear propulsion. Russia’s Rosatom has been operating FNPPs in the country’s Far East since 2020, which remains the only FNPP in operation today and is being trialed to support the company’s next-generation RITM PWR SAMR-based concepts. Meanwhile, the list of FNPP aspirants includes China, Indonesia, South Korea, and the U.S. For example, Core Power launched in February the “Liberty” program, a U.S.-anchored initiative targeting commercialization of FNPPs by the mid-2030s. The program will mass-produce modular FNPPs using shipyard construction to supply power to ports, coastal regions, and offshore sites, with centralized servicing and maintenance.

Advanced MSRs are expected to underpin the designs, with a second phase introducing nuclear propulsion for commercial vessels. Core Power said it plans to open orders in 2028 and is working with regulators to establish safety and liability frameworks. Elsewhere, U.S.-based shipping classification society ABS in December 2025 issued an AIP for Samsung Heavy Industries’ FNPP design using twin KAERI SMART100 PWR SAMRs. Early FNPP projects can help resolve key challenges by establishing shipyard SAMR fabrication capabilities, advancing marine classification standards, and clarifying offshore operating models while avoiding complex port entry and propulsion licensing issues. As a result, FNPPs may serve as a bridge market, helping to develop supply chains, safety frameworks, and regulatory practices before large-scale commercial nuclear propulsion emerges.

Trouble on the High Seas?

Despite momentum in the sea-based SAMR segment, the sector’s core constraints remain. At the top of the list is the fact that the industry still lacks a globally harmonized regime for port access, nuclear liability, safeguards, emergency preparedness, and crew competency. While several initiatives are advancing to address these gaps, maritime nuclear applications continue to raise legal and regulatory questions that are yet to be standardized. The most advanced milestones today are a collection of early approvals, frameworks, and studies. For now, nuclear shipping remains a future option with significant potential, with progress measured less by conceptual designs and more by whether international regulators can establish a workable licensing and operating system. Whether this ultimately leads to widespread commercial deployment remains uncertain, but compared with our 2024 first look at the sector, nuclear-propelled shipping in 2026 appears less like a distant concept and more like a serious and groundbreaking future option.

This article was originally published in the April 13, 2026 issue of the Ux Weekly.