Charting Safe Waters for Nuclear Shipping
Risk Based Design Framework for Nuclear Powered Commercial Vessels
S. Mougis (TU Delft - Mechanical Engineering)
A.A. Kana – Mentor (TU Delft - Mechanical Engineering)
R. J. Berendschot – Mentor (C-Job Naval Architects)
N. de Vries – Mentor (C-Job Naval Architects)
H. Polinder – Graduation committee member (TU Delft - Mechanical Engineering)
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Abstract
The global transition towards more sustainable energy systems is placing increasing pressure on the maritime industry to reduce its greenhouse gas emissions. In response, the International Maritime Organization (IMO) has set the ambition of reaching net zero greenhouse gas emissions by/or around 2050. Achieving this objective requires the development and adoption of alternative propulsion technologies capable of supporting the energy demands of commercial shipping. Nuclear propulsion represents an attractive candidate, particularly for long distance shipping, because it can provide continuous high density energy, long operational endurance, and very low operational greenhouse gas emissions during onboard operation. However, its application introduces safety and integration challenges.
Existing maritime, nuclear, and classification requirements provide relevant safety principles, but they remain fragmented and do not provide a single modern methodology for assessing nuclear and maritime hazards together and translating the resulting findings into ship design decisions. To address this
problem, the work was divided into two distinct phases.
The first phase established the technical, regulatory, and methodological basis of the study through a literature review. It examined the fundamentals of marine nuclear propulsion, the shipboard systems required to support nuclear safety, relevant safety frameworks and representative accident scenarios, and available risk assessment methods. From this review, Hazard Identification Study (HAZID) and Bowtie analysis were selected within a Formal Safety Assessment (FSA)-informed structure, supported by Defence-in-Depth (DiD) and an As Low As Reasonably Practicable (ALARP) approach.
The second phase applied this methodology to a reference nuclear powered bulk carrier. A HAZID identified and ranked 95 scenarios across five functional nodes, after which three representative top events were examined in greater detail using Bow-tie analysis. The assessment identified weaknesses related to barrier dependencies, system segregation, release management, electrical support, heat
rejection, and severe condition mitigation. These findings were translated into six concept level design recommendations and implemented in a second design iteration.
Twenty scenarios affected by the recommendations were reassessed. Following the second design iteration, no High- or Extreme-risk scenarios remained within this subset, while the number of Mediumrisk scenarios decreased and the number of Low-risk scenarios increased. The study concludes that the methodology proposed in this research provides a structured and traceable framework for linking hazard identification, barrier assessment, design improvement, and reassessment. A key finding is that the nuclear installation and the vessel should be developed as one integrated safety system rather than as separate design domains.
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