Interest in nuclear applications in the maritime industry has been growing significantly in recent years and LR recognised that both Guidance and Rules were going to be required. However, the starting point for delivering these was underdeveloped, with only a limited range of candidate technologies and development of regulation in the very earliest stages of discussion.
As developers accelerate work on small modular reactors and advanced marine nuclear systems, the industry’s ability to adopt these technologies will depend on the strength and clarity of the technical frameworks surrounding them. LR’s Navigating Nuclear Energy in Maritime provides that framework and sets out a roadmap for first movers.
The document tackles the fundamental challenge the industry faces today: the absence of a mature, internationally harmonised regulatory architecture for civil maritime nuclear applications. While the International Maritime Organisation (IMO) and International Atomic Energy Agency (IAEA) each operate robust frameworks, neither directly addresses the modern engineering integration, classification assurance, or flag state-specific safety demonstration required for a contemporary mobile nuclear power plants at sea. LR’s guidance bridges this gap by articulating how nuclear and maritime regulatory philosophies can be reconciled into a coherent development pathway.
The guidance emphasises the complete systems integration of maritime and nuclear domains. Rather than treating the reactor as an isolated subsystem, the document positions it at the centre of a tightly coupled set of engineered structures, systems and components. This includes interfaces with propulsion, electrical distribution, heat rejection systems, containment structures, and the wider machinery space, each subject to classification requirements, national nuclear safety, security and safeguards regulation and maritime environmental loading.
Safety is key
Key to this approach is the application of safety classification. LR outlines how Safety classification of structures, systems and components (SSC’s) should be performed in accordance with nuclear and marine safety functions, enabling design teams to adopt graded approaches to assurance. This establishes a foundation for demonstrating compliance both with classification rules and with nuclear regulators’ expectations for deterministic and probabilistic safety analyses. The document goes further by detailing how environmental conditions unique to maritime operations, such as metocean loading, slamming, vibration, shock and long-term fatigue, must be integrated into the definition of the reactor’s Design Basis Envelope, and subsequent nuclear safety case development. This ensures that reactor performance and containment integrity remain robust across the full spectrum of plausible operating and accident scenarios.
The guidance recognises that goal-based design methodologies will be central to the sector’s progress. Prescriptive codes alone cannot address the novel design features and operating contexts of advanced reactors at sea. It offers a consistent approach aligned with IMO goal-based standards and nuclear As Low As Reasonably Practicable (ALARP) principles, allowing project teams to demonstrate an equivalent or superior level of safety where prescriptive rules are absent. This is essential for complex systems where traditional rulebooks do not yet exist.
Security and protective measures are addressed with the same technical rigor as safety considerations, treating security as a distinct but integrated discipline. The guidance incorporates Global Nuclear Security Partners (GNSP) expertise to define security-by-design requirements grounded in Design Basis Threat analysis, physical protection system engineering, cyber protection architecture and safeguards accounting. It stresses that these requirements must be engineered into the earliest phases of design, as retrofitting a nuclear security architecture into an existing vessel is neither practical nor acceptable to regulators. The emphasis on integrated safeguards planning is particularly important given the trans-jurisdictional nature of maritime operations, where nuclear material accountability must remain continuous across multiple state boundaries.
Crew training
The document also brings clarity to operational engineering considerations. Workforces will require Suitably Qualified Experienced Personnel (SQEP) -standard training, supported by reactor-specific certification schemes. Emergency response planning must incorporate both maritime conventions and nuclear incident protocols, aligning shipboard procedures with coastal state and flag administration expectations. Upstream and downstream support models, covering fuel transport, refuelling, maintenance, waste management, and eventual decommissioning, are treated as engineered systems in their own right, rather than peripheral concerns.
Insurance and finance are presented through a technical lens, drawing on NorthStandard’s input to explain how liability frameworks and risk models must evolve to accommodate nuclear propulsion. The guidance outlines the intersections between classification, statutory certification, nuclear licensing and insurance underwriting. This integrated approach provides the technical predictability that insurers require before they can engage meaningfully with first-of-kind maritime nuclear projects.
The adoption roadmap represents the technical culmination of the guidance. It is not a narrative overview but a structured sequence of engineering, regulatory and operational activities: design definition, regulatory engagement, safety case development, security architecture, operational readiness and lifecycle assurance. It encourages project teams to develop verifiable engineering evidence early, establish regulatory pathways before committing to design freeze, and integrate nuclear and maritime requirements into a single coherent development plan.
Nuclear technology has the potential to deliver transformative capability for the maritime sector, but only if supported by rigorous, technically grounded frameworks. With Navigating Nuclear Energy in Maritime, LR provides the most comprehensive pathway the industry has seen. It offers clarity where uncertainty has stalled progress, establishes a shared technical language for stakeholders, and sets the benchmark for safe, secure and commercially viable nuclear integration at sea.
