The shipping industry views ammonia as an appropriate carbon-free option because it contains a high proportion of hydrogen but exhibits low flammability under typical conditions. However, there is limited literature addressing the toxic dispersion risks involved in ship-to-ship bunkering. Here, we performed a non-probabilistic, deterministic evaluation of ammonia leakages in bunkering operations at four South Korean principal ports via ALOHA simulations. The 15%, 20%, and 25% ammonia concentration scenarios were simulated. Simulations yielded AEGL-1 dispersion distances of up to 831 m (Busan), and AEGL-2 and AEGL-3 distances of ≤381 and ≤137 m, respectively. These findings were the foundation for establishing three conservative control zones: toxic (200 m), safety (500 m), and security (1000 m). These findings contribute to port-specific emergency preparedness and maritime safety planning, as well as to the regulatory use of ammonia as a marine fuel with scientific evidence.
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