Application of LOPA Method in the Assessment and Risk Management

Sonia Masmoudi

In order to determine the criticality of a risk, an assessment of the probability of occurrence (notion of frequency) and of the impact (notion of severity) are to be estimated. The criticality is the product of the probability of its occurrence and the impact that the risk has on the project, hence on the whole company. So, the practice of matrix or the criticality grid considering these two dimensions is necessary. However, the criticality grid involves the insufficiencies inherent to the subjective behavior of expert judgments and to the imprecise information engaged in the assessment of the risk. Taking into account the problems of the imperfection implied in the Conventional Criticality Matrix (CCM), the objective of this work is to develop a Fuzzy Criticality Matrix (FCM) to overcome these difficulties. The proposed model aims at improving the system of fuzzy inference. To lead an exhaustive analysis, the provision of a method allowing the precise definition of the possible causes and the entire observable consequences will be essential. All these reasons justify the utility of inductive analysis by the HAZOP method, during the phase of the risk qualitative analysis phase, in order to develop accident scenarios and a "barrier" approach using the LOPA method to determine the frequency of the reduced consequence of these scenarios. The LOPA method begins with data developed during the HAZOP study and takes into account each identified hazard by documenting the initiating cause and the protective which avoid or limit the danger. The proposed approach is applied to a test system which is the company SAROST S.A.