Abstract
Unlike some of its neighboring European countries, in Germany the definition of plausible accident scenarios primarily follows a purely deterministic concept. This applies, in particular, to dispersion calculations according to the Major Accident Ordinance (Störfall-Verordnung) and the Federal Immission Control Act (Bundes-Immissionsschutzgesetz, BImSchG), which must be carried out for accidental release scenarios in order to obtain the license-to-operate for chemical plants. The fundamental dilemma of the deterministic concept is the need to commit to specific, predefined release scenarios in order to achieve acceptance by all stakeholders (e.g. regulatory authorities, asset owners, residents, emergency responders, society). Different stakeholders might not necessarily agree on predefined model assumptions for the dispersion calculation. The intention of this paper is to present a deterministic and well-established approach for dispersion calculations, which has been used in many chemical companies throughout Germany for more than three decades. By outlining the multitude of conservative assumptions taken, we aim to show why this is a conservative and viable approach, offering a solid basis for decision-making and hazard assessment.
