Safety is an important task in chemical plants and plays a significant role throughout the whole design process. To ensure the safety and environmental demands and to minimise later plant changes, safety analyses are already performed in early design phases. Due to still manifold drawbacks of applied methods e.g. Hazop-studies, computer-based approaches are subject to research. This contribution introduces a new qualitative, model-based approach to process hazard identification by simulation and reachability examinations of dangerous plant states.