Nuclear at Sea: Navigating Regulatory Confluence

A new paper titled “Facilitating Global Deployment of Floating Nuclear Power Plants” has been published by World Nuclear Association’s Cooperation in Reactor Design Evaluation and Licensing (CORDEL) Working Group. This paper highlights the benefits of the technology and focuses on progress made in the regulatory space, which is required for their international deployment.

The pledged tripling of nuclear power between now and 2050 that is needed to meet climate and energy security goals will require capacity to expand by an average of 40 GWe per year until 2050. This is equivalent to about 20 large reactors and 70 small modular reactors (SMRs) coming online each year, more than four times the current rate of deployment. New approaches to design, licensing, construction, deployment, and project management are therefore needed to accelerate nuclear new build. Floating nuclear power plants (FNPPs) are proposed within this context as a means of significantly reducing time and cost of deployment.

History of Nuclear at Sea

Nuclear power has a long and distinguished history at sea, starting with the launch of the USS Nautilus in 1954. Its applications have largely been in the naval domain, powering more than 500 ships to date, both above and below the waves. Civilian use of nuclear energy at sea hasn’t been as expansive; it has principally been used to propel icebreakers and has seen a limited use in merchant cargo ships.

Vessels hosting nuclear reactors to produce energy for the grid rather than propulsion have been deployed, notably the American Sturgis MH1-A in 1978 and more recently the Russian Akademik Lomonosov in 2020 (Figure 1). These ships, FNPPs, supply reliable clean power to remote or isolated areas. Importantly, they are constructed in shipyards and deployed to locations that require far less site preparation than traditional land-based nuclear power plants, thereby providing a potential key to unlocking the acceleration of the needed nuclear deployment. Alongside Rosatom, other World Nuclear Association members, including Core Power, Korea Hydro & Nuclear Power (KHNP), and Salftoss Energy, are aiming to build and deploy FNPPs to meet this demand.

A Buoyant Nuclear Solution

FNPPs bring many of the benefits of SMRs’ innovative approaches and combine them with unique advantages offered by their water-based deployment locations. For example, modern shipyards use modular construction approaches, piecing together vessels from pre-constructed modules delivered from factories. This approach reduces build times compared to traditional methods, brings factory-level quality control to vessels, and enables scaling as multiple pre-constructed modules can be built at the same time and assembled without waiting for critical structures such as decks or frames to be complete. In this context, the FNPP’s nuclear steam supply system and conventional island would be modules, to be assembled into the vessel like any other. Separating the construction and deployment locations allows for the construction to start in parallel with site preparations, further reducing deployment timelines.

Hosting nuclear reactors on vessels sidesteps several challenges that land-based reactors face. Some of these are a direct consequence of being in water; the ultimate heat sink surrounds the vessel and cannot be lost. Meanwhile, offshore emplacement could provide greater resilience to tsunamis and earthquakes.

Site preparations at the eventual deployment location are also considerably reduced compared to land-based NPP counterparts. On-shore facilities typically provide supporting services, security, and the connection to the grid, rather than nuclear safety-significant systems, meaning they aren’t subject to the same nuclear safety requirements.

FNPPs’ transportability also enhances survivability as the vessel can be relocated to avoid forecast meteorological hazards, while providing economic benefits as FNPPs can be redeployed to new locations to respond to changes in energy demands. Their transportability also allows for centralised refuelling, servicing, and decommissioning hubs to be developed, making use of optimised shipyard processes once more.

These extensive benefits make FNPPs an attractive option, notably for countries that are looking to add nuclear to their energy mix and are open to relying on another country to do so rather than developing significant domestic nuclear infrastructure. The only currently operating FNPP, Akademik Lomonosov, was deployed in a domestic context: built, licensed, and operated in Russia and Russian territorial waters. Challenges exist for the international deployment of FNPP, however, as these vessels exist at the intersection of international nuclear safety and marine frameworks, and must be licensed and supervised by both nuclear and maritime regulators.

Shipshape Regulation for International Waters

On the nuclear side, the International Atomic Energy Agency’s (IAEA’s) “Convention on Nuclear Safety” establishes the high-level obligations for contracting parties that operate land-based civil nuclear power plants to maintain a high level of safety by establishing fundamental safety principles to which signatory states would subscribe and IAEA safety standards provide guidance. Meanwhile, on the marine side, the “United Nations Convention on the Law of the Sea” establishes the legal framework for all maritime activities, and the International Maritime Organization’s (IMO’s) “International Convention for the Safety of Life at Sea (SOLAS)” provides the safety standards for merchant ships. Elements of both frameworks either are, or could be, applicable to FNPPs. The World Nuclear Association paper explores these applicabilities, emphasising the need for a common global understanding and position, to facilitate a standardised approach to the worldwide deployment of FNPPs.

Alongside safety, security and safeguards make up the other two-thirds of the 3S approach to nuclear energy that must be reconciled with marine counterparts. These requirements do present challenges, such as accounting for nuclear materials on FNPPs during transit and when deployed to remote locations or ensuring restricted access to sensitive plant areas but not compromising rapid vessel evacuation. Work will be needed from both the IMO and the IAEA to marry requirements in these areas. However, FNPP engineers must also contribute to resolving these issues by incorporating safety, security, and safeguards in the design stage of projects. FNPPs may well also provide an opportunity to optimise and bring innovations to current practices, notably for safeguards.

Setting Sail for Success

The worldwide deployment of FNPPs has the potential to help turn the tide on emissions and meet energy security goals more quickly, due to their ability to scale production and reduce construction requirements. Their manufacture and deployment within a national context are proven, but facilitating their transit across international and third-country waters requires a common regulatory framework.

Greater international cooperation is needed to facilitate this deployment, which could also yield dividends to the wider nuclear industry using novel approaches to safety, security, and safeguards. World Nuclear Association’s CORDEL Working Group has long advocated for the alignment of regulatory requirements and design criteria for land-based nuclear power plants and believes the same is necessary for those at sea. The recent decision by the IMO to review the “Code of Safety for Nuclear Merchant Ships” and parts of the SOLAS convention relevant to FNPPs is a welcome one, and an important step toward the alignment of member state representatives with an interest in FNPPs to ensure the work stays on course. To find out more, read the paper “Facilitating Global Deployment of Floating Nuclear Power Plants” published by World Nuclear Association’s CORDEL Working Group. Also, consider attending World Nuclear Symposium, taking place September 3–5, 2025, in London, UK, which will feature a session on navigating maritime nuclear applications as part of the Energy Users Summit on September 3.

—Ronan Tanguy is programme lead for Safety and Licensing with World Nuclear Association.