ABSTRACT
The paper presents a Probabilistic Risk Assessment (PRA) method for the security of supply of a gas network. The method is based on a procedure for automatic generation of fault trees, which estimate the probability of disruption of the gas delivery from terminals/storages to each consumer nodes in the gas network. The method allows probabilistic analyses of the availability of the demand nodes and of the overall availability of the gas network. To assess the importance of each network component, risk achievement worth and risk reduction worth importance measures are utilized. The aim of the developed method is to assess potential weakness in the gas network as well as to be used as an analysis tool during expansion planning and maintenance scheduling activities. The framework developed in the paper leverages on steady-state analysis of the gas network performed using a physical flow/pressure model. The impact of a component failure on the gas supply interruption at different demand nods is assed and contrasted to the PRA results. The framework is exemplified with reference to the reduced UK gas network. The results provide insights to support a robust reliability assessment of the gas network. Moreover, the probabilistic mapping of the most important components in the gas network provides the means for assessing optimal strategies for maintenance schedule as well as to prioritize improvements of the gas network aiming for effective risk reduction.
