Emergency response plays an important role in preventing or delaying the domino effect of chemical accidents. Requirements for emergency response to a major accident may exceed the capacity of the emergency department within the region of responsibility for the accident, in which case multi-department emergency response is necessary. In this work, modeling problems related to the arrival of emergency teams at different times in multi-department emergency response are discussed. These problems will dynamically influence the time to failure of adjacent facilities in the event of a fire. A timed colored hybrid Petri-net (TCHPN) approach is proposed to solve these problems and analyze multi-department emergency response processes. An example of responding to a tank fire illustrates the proposed approach. An emergency response process is simulated, and probabilities of fire escalation prevention under different fire levels are analyzed.

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Major industrial accidents occurring at so-called major hazard installations may cause domino accidents which are among the most destructive industrial accidents existing at present. As there may be many hazard installations in an area, a primary accident scenario may potentially propagate from one installation to another, and correlations exist in probability calculations of domino effects. In addition, during the propagation of a domino effect, accidents of diverse types may occur, some of them having a synergistic effect, while others do not. These characteristics make the analytical formulation of domino accidents very complex. In this work, a simple matrix-based modeling approach for domino effect analysis is proposed. Matrices can be used to represent the mutual influences of different escalation vectors between installations. On this basis, an analysis approach for accident propagation as well as a simulation-based algorithm for probability calculation of accidents and accident levels is provided. The applicability and flexibility of this approach is discussed while applying it to estimate domino probabilities in a case study.

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Chemical production- or storage facilities may have a strong appeal to terrorists due to their potential for causing great losses and possible huge societal impact. In view of the deficiency of attack trees, especially the impact of attacker numbers on the attack time, a timed colored Petri-net based attack process modeling approach, as well as a simulation based security failure probability analysis approach for security management, is proposed in this paper. The number of attackers has a key influence on the logic relationship of attack events. For performing the events represented by the logical gates (mainly AND gate and OR gate) of an attack tree, the influence of a different number of attackers on the attack time is discussed, and corresponding timed colored Petri-net based modeling approaches are provided. Comparing the duration of an attack process with an assumed interval of security inspection, a security failure probability can be obtained.

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In the chemical process industry, large quantities of different flammable substances are stored in tank farms. Due to potential mutual impacts among the tanks, severe domino accidents may occur after a tank catches fire. The emergency response to a tank fire may influence the development of the accident and impact the occurring of escalating events or so-called domino effects. In this paper, a fuzzy Petri-net (FPN) based reversed reasoning approach is proposed to analyze emergency response actions impacting domino effects. FPN is utilized to deduce the consequence-antecedent relationship between an accident and the emergency response actions. To analyze and compare the impacts of the actions on a domino effect, the backward reasoning is of special interest and often preferable when the occurrence probability of domino effects is known. As a tank fire accident in an oil depot usually lasts for a certain period of time, and as it may be greatly influenced by emergency response actions, it is taken as an example to illustrate the proposed approach.

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In the chemical process industry, flammable gases are handled or stored in many production- or storage facilities. They can cause a vapor cloud explosion (VCE) accident if they come free from their containment and there is an ignition. A knock-on effect propagation from a primary VCE to one or more subsequent VCE(s) forms the cascading effect of VCEs. A new methodology of probabilistic Petri-net (PPN), which is an extension of Petri-net, is proposed to model the cascading effect and estimate the probabilities of escalation VCEs. The definition of what is a PPN is provided and three types of probabilistic relationships based on PPN are modeled. Further, the VCE cascading analysis approach based on Petri-net reasoning (execution of transitions) is discussed. The approach is illustrated by an example analyzing a VCE cascading effect in atmospheric tanks containing gasoline.@en