Safety analysis of liquefied natural gas bunkering and simultaneous port operations for passenger ships

The use of liquefied natural gas (LNG) has been recognized as an effective alternative fuel for marine propulsion, evidently, a growing number of vessels, including passenger ships, is already running on such a fuel. While LNG bunkering can be performed in several ways, depending on transferred volumes and managerial considerations, the time spent for LNG bunkering is regarded to be a key factor to ensure the costeffectiveness of such operation, since a minimization of bunkering duration at the berth will make port infrastructures available for more vessels. As a result, passenger embarkment is simultaneously conducted with ship bunkering, which may increase the potential risk to individuals both onboard and nearby. Given this background, this paper is to investigate the potential risk of passenger vessels with the identification of credible scenarios for port operations that can be carried out simultaneously with LNG bunkering. An approach of quantitative risk assessment is applied to determine the risk levels pertinent to proposed scenarios. For frequency analysis, the technique of the fault tree analysis is adopted to integrate the influence of human error and management policy to the likelihood of unwanted events. Consequence analysis is conducted in aids of a commercial software to simulate the impact of LNG dispersion and fires. Research findings have shown that simultaneous operations have a negative impact both on frequency and consequence of accidental scenarios arising from LNG bunkering, taking the risk beyond lower acceptance criteria. Finally, a quantification of the risk increase is proposed to help stakeholders identify criticalities and reduce the risk contributions of simultaneous operations.