In June 2025, the 110th session of the International Maritime Organization’s (IMO’s) Maritime Safety Committee recognised that the Code of Safety for Nuclear Merchant Ships was outdated and represented a barrier to the adoption of advanced nuclear technologies for ships and formally agreed that the code should be revised to address this.
This code, issued in 1981, was initially drafted to define safety requirements to allow the use of pressurised water reactors (PWRs) for merchant ship propulsion, the only technology assessed suitable for naval use at that time. Since then, increasing concerns regarding the consequences of climate change, the development of new reactor technologies and the strengthening of nuclear safety standards have led the IMO to decide to revise the code in order to bring it to the current safety standards and expand the possibility of using nuclear technology for the propulsion of merchant ships beyond the sole technology of PWRs.
Meanwhile, the International Atomic Energy Agency (IAEA) is about to launch its Atomic Technologies Licensed for Applications at Sea (ATLAS) project, which aims to establish a framework for the safe and secure deployment of civil nuclear applications at sea, specifically merchant ships and floating nuclear power plants. The IAEA, in co-operation with the IMO, will oversee and guide this global effort, using its established standards for nuclear safety, security, and safeguards.
The Western European Nuclear Regulators Association (WENRA) says it recommends first that the IMO and IAEA work closely together to ensure that their respective activities are carried out in a consistent manner, and the revision of the code be aligned with the most up-to-date IAEA safety standards, “preferably referring, where appropriate, to each other’s set of safety requirements”. In particular, it says, the revision of the code should achieve the highest safety, security and safeguards levels reasonably achievable, given the specific hazards of the maritime environment.
“Then, given the specificities of the maritime environment and its hazards, and the diversity in the current maturity level of the reactor technologies considered, WENRA further calls for the demonstration of a sufficient level of maturity of both the design, the safety case and the licensee, before a reactor (light water or advanced) is licensed to be used at sea” WENRA said. “Due to the strong international component the naval sector has, with its inherent potential for transboundary consequences and the fast development of new reactor technologies worldwide, WENRA reminds that these conditions are essential for considering the harmonisation of safety requirements and criteria at the international level.”
WENRA also calls for a revision of the code that ensures a consistent application of relevant safety requirements and navigation authorisation procedures across countries. “As a consequence, WENRA encourages the IMO to consider, in close coordination with the IAEA, a revision of the code which firmly establishes the safety objectives and then provides sufficiently comprehensive and detailed safety requirements to be used by national competent bodies to grant the ships navigation licenses with the specific chosen technology.”
WENRA members confirmed their willingness to support their national competent authorities in the work conducted by the IMO by contributing, in their field of competences, to the revision of the code.
WENRA is a non-governmental organisation comprised of senior nuclear safety regulators from across the European Union and Switzerland, the UK and Ukraine. Currently 18 members, two associated members and 12 observers are represented in WENRA.
The shipping industry consumes about 350 million tonnes of fossil fuel annually and accounts for about 3% of total worldwide carbon emissions. In July 2024, the shipping industry, via the IMO, approved new targets for greenhouse gas emission reductions, aiming to reach net-zero emissions by or around 2050.
