GOING NUCLEAR: Legal Solutions for Nuclear Powered Ships

The 2023 IMO greenhouse gas strategy and the 2025 net-zero framework (set to enter into force in 2027) have placed the world of shipping under increased pressure to decarbonise. Batteries can power ferries and vessels for use in harbours but are impractical over long distances. Other potential solutions, like hydrogen, are too bulky to store at sea.

Nuclear-powered vessels present a transformative opportunity for the decarbonisation of global shipping. However, their deployment and development is critically dependent on creating a robust and realistic legal and regulatory framework which facilitates the new technology, but also maintains appropriately high standards of safety, security and public trust.

What is a nuclear-powered ship?

A nuclear-powered ship uses a nuclear reactor as its primary energy source instead of fossil fuels.[1] The principles of nuclear fission within a ship’s reactor are similar to those in land-based powerplants, but the necessary power output to drive the ship is much lower. Given the constraints of space available in vessels, most naval reactors rely on highly enriched uranium fuel which generates more energy. The result is that nuclear-powered ships can operate at high speeds for 20-30 years without refuelling and with zero exhaust emissions.

The World Nuclear Association’s recent estimate is that over 160 ships worldwide are nuclear powered.[2] The technology is developing fast and, whereas the original interest in developing nuclear-powered merchant ships did not progress to commercial scale (understood largely to be on grounds of cost), interest has, since 2020, significantly increased. For example, it has been suggested that the first nuclear commercial ships in the UK could be in operation by 2032.[3]

The legal vacuum

The international legal framework remains, in important respects, as it was in 1962 when the Convention on the Liability of Operators of Nuclear Ships and Additional Protocol was adopted in Brussels but never entered into force.

The relevant treaties which are in force (e.g. the Paris Convention on Third Party Liability in the Field of Nuclear Energy 1960 and the Vienna Convention on Civil Liability for Nuclear Damage 1963), expressly exclude nuclear reactors comprised in any means of transport. Similarly, national legislation on matters such as port and marine safety is in some cases outdated and was not drafted with nuclear-powered shipping in mind.^[4]

Therefore, in the event of a nuclear incident caused by the propulsion reactor of a ship, there is a legal vacuum. This creates uncertainty for companies to invest in and operate nuclear-powered merchant vessels.

Taking the UK as an example, the Nuclear Installations Act 1965 which implements the UK’s international treaty obligations in respect of nuclear liability, does not extend to reactors comprised within any means of transport. As for the Government’s proposal for a Nuclear Regulation Bill, this represents the most significant proposed overhaul of the UK’s nuclear regulatory architecture in decades and will be the legislative vehicle through which the Government intends to implement the 47 recommendations of the independent Nuclear Regulatory Review 2025 led by John Fingleton (the “Fingleton Review”).[5] However, the Fingleton Review – and therefore the Government’s response – does not address the issue of nuclear-powered ships or vessels. Therefore, this is not an issue, one would expect, that the Bill will address.

In the absence of a dedicated regime, those impacted by a nuclear shipping incident would be forced to rely on common law causes of action — negligence, nuisance, and the rule in Rylands v Fletcher — which present substantial difficulties concerning remoteness of damage, multi-party liability, conflict of laws, and cross-border enforcement of judgments. These are manifestly inadequate mechanisms for addressing what could be a significant, transboundary event.

This legal vacuum raises many practical issues for the deployment of nuclear-powered ships. For example, how can a port state accept a nuclear ship with confidence that compensation will be available in the event of an incident? And how can a shipowner secure the insurance that ports might require as a condition of access?

The regulatory landscape is evolving. The IMO’s revised workplan for SOLAS Chapter VIII and the adoption of a revised Code of Safety for Nuclear Ships by 2030, together with the IAEA’s ATLAS initiative, signal positive engagement with safety standards. However, neither initiative is designed to address the question of civil liability and compensation.

What is the solution?

If there was a will on the part of the international community, it is possible that the Brussels Convention on the Liability of Operators of Nuclear Ships and Additional Protocol 1962 could be updated by a Protocol to bring it in line with modern regimes. However, this has not happened to date and plainly it would take some years for this to be negotiated.

So, for now, and in the absence of an international legal framework for nuclear-powered vessels, a potential solution is for states to rely on bilateral agreements.

A bilateral agreement in this context is essentially a ship-specific, state-specific and likely also a route-specific arrangement whereby both sides agree to a set of obligations. Those obligations would include, for example, allocation of liability in the event of an accident, applicable emergency response arrangements, and a range of technical and administrative provisions including safety standards, permitted reactor types and use of ports.

This instrument can be implemented quicker than a treaty due to having less negotiating states involved, and none of the treaty ratification hurdles. It is also more flexible. Contracting states can draft the terms to address the specific legal questions arising for the nuclear vessels operating between their countries and tailor the provisions to the specific reactor technologies and operational profiles of the vessels in question.

Successful bilateral agreements can then become templates for other states to adopt, gradually building a network of routes on which nuclear vessels can operate ahead of any international legal regime being established.

For example, following the US-UK Technology Prosperity Deal Memorandum of Understanding (signed in September 2025) whereby a commitment was made to explore the establishment of a maritime shipping corridor between the countries for nuclear-powered vessels, and in the event that such a corridor is established, a bilateral agreement between the US and UK could be drafted to regulate the passage of nuclear ships within that route.

There are some historic examples of bilateral agreements in this context to draw upon, including those concluded by the US for the Nuclear Ship Savannah (the first nuclear-powered merchant ship which was launched by the US in 1959) concerning its visits to different countries. An analysis of the US/UK and US/Belgium agreements reveals a consistent core architecture: prior governmental approval for port entry, compliance with Chapter VIII of the International Convention for the Safety of Life at Sea 1974, provision of a safety assessment, host state inspection rights, restrictions on radioactive waste disposal, accident reporting obligations, a clear indemnification structure with a defined liability cap, waiver of sovereign immunity, and submission to host state jurisdiction.

These features provide a robust template which, appropriately modernised to reflect current reactor technologies, updated liability limits consistent with the Paris Convention as amended, comprehensive definitions of nuclear damage, and adequate insurance requirements, could form the basis of a new generation of bilateral agreements.

Challenges for bilateral agreements

There are several difficult issues that would apply to any bilateral agreement.

One is who the ‘operator’ of a nuclear-powered ship should be. Operators of nuclear power plants are liable for any damage caused by them, regardless of fault. This is important as the structure of insurance of nuclear installations is different from ordinary industrial risks. World-wide, almost all legal regimes transfer third party liability for nuclear accidents exclusively towards the operator of a nuclear plant – referred to as “channelling”. A bilateral agreement would need to secure itself against a number of issues here, including defining who the “operator” is and how this interacts with the role of the master of the ship.

To take a blunt hypothetical scenario: an operator makes the decision that a reactor needs to be shut off for safety reasons, however the captain of the ship needs more power to avert a risk for example an obstruction in the sea. In those circumstances there might be conflict between the ‘operator’ of the source of nuclear power and the orders of the captain of the ship.

Another issue is the threat of war and terrorism. Like many aspects of trade and relations between states, nuclear-powered vessels presume peacetime cooperation and orderly marine traffic. Recent global events demonstrate that these presumptions cannot be taken for granted, most notably for shipping this is illustrated by the Strait of Hormuz. There is no straightforward answer as to how nuclear-powered vessels are to navigate these difficult geo-political events and risks. However, that reality must be borne in mind when routes are negotiated for vessels within bilateral agreements.

Conclusion

The protracted timelines inherent in multilateral treaty negotiation and ratification mean that bilateral agreements will, for the foreseeable future, remain the primary mechanism through which the legal vacuum for nuclear-powered ships can be addressed. However, much discussion needs to be had between legal, insurance, technical and political worlds as to how to build one that is fit-for-purpose.

Such agreements are particularly timely in light of the UK-US Memorandum of Understanding in 2025 and the establishment of the UK Maritime Nuclear Consortium in January 2026. If the commitment to explore a maritime shipping corridor between the two countries is to be realised, a bilateral agreement addressing both safety regulation and civil liability will be essential.

The authors of this article, along with Ian Truman at Burges Salmon, will be presenting a detailed paper on these issues at the upcoming International Nuclear Law Association Congress 2026.

[1] See Maritime and Coastguard Agency, ‘Guidance: MGN 679 Nuclear Ships’ (published 1 December 2022), available at: https://www.gov.uk/government/publications/mgn-679-nuclear-ships.

[2]https://world-nuclear.org/information-library/non-power-nuclear-applications/transport/nuclear-powered-ships

[3] See: https://www.lr.org/en/knowledge/horizons/october-2025/nuclear-energy-moves-closer-to-the-commercial-fleet/.

[4] In the UK see Department of Transport and Maritime and Coastguard Agency, Ports & Marine Facilities Safety Code Guidance for all ports, harbours, marine facilities, berths and terminals (April 2025). Available at: https://assets.publishing.service.gov.uk/media/67fd175bed87b81608546666/port-marine-safety-code.pdf

[5] Department for Energy Security and Net Zero and Ministry of Defence, ‘Independent report Nuclear Regulatory Review 2025’ (published 23 April 2025). Available at: https://www.gov.uk/government/publications/nuclear-regulatory-taskforce.