Use of quantitative risk assessment to enhance the safety of ships using ammonia as fuel

Efforts to decarbonise the shipping industry have led to the consideration of several alternative fuels, including ammonia. Safety concerns have been raised about the use of ammonia due to its toxicity. Quantitative risk assessment is applied to two vessel designs that use ammonia as fuel (a containership and a tanker). The effectiveness of risk reduction measures and the effect of design changes is studied. Risk criteria for use in this context are discussed and the results compared with those criteria. The method enables identification and evaluation of a risk reduction measure that is not currently mandated within the design requirements for such vessels. Following risk reduction, the individual risks were shown to be at a tolerable level and below the project criterion. The results of sensitivity analyses are also presented.