Dynamic risk assessment in the process industries: proposal of a methodology based on the system dynamics approach
Résumé
Due to the relationships between human, technical and organizational factors, process industries can be considered as complex systems for which risk assessment is a key activity in order to promote a sustainable industrial development. This consideration is particularly significant for SEVESO industries that must provide safety reports to the public authorities and inspection services. The core of the safety report is mainly dedicated to the risk assessment which needs to model the industrial system with regards to its complexity. Most often this step is partially treated, or simplified or avoided. In the same time, accidents investigations have shown that their occurrence is frequently related to the complexity of industrial systems too. In order to take into account the complexity of the industrial systems and their spatial and temporal dynamic, this paper aims to propose a method based on the System Dynamics theory developed by Forrester in the 60's in order to model and simulate the behavior of a technical system. This methodology is applied in the context of risk assessment and contributes to support the development of a Dynamic Risk Assessment Framework dedicated to such economical activities. This framework includes four complementary steps applied in a case study: i) the modeling of the system using the systemic theory principles and terms; ii) the implementation of this model into a Dynamic System platform for its simulation; iii) the simulation of the system using normal and abnormal scenarios in order to identify and to estimate the consequences of the potential deviations; iv) the assessment of the proposed barriers efficiency. As a conclusion, the paper presents the benefits and limits of this approach in the safety reports and proposes ways to improve and generalize the proposed methodology and to implement the framework.