Abstract
Accidents involving accidental release of liquefied petroleum gas (LPG) can cause very serious damage to people and structures. Such as, for example, the derailment of a freight train carrying LPG, which occurred in Viareggio (Italy) on 29 June 2009 or the accident involving the fixed tank installed at the end user, which occurred in Gravedona (Italy) on 11 July 2019. The danger of LPG derives from its flammability and its tendency to form a dense cloud of vapour which is dispersed in atmosphere, even at a significant distance from the release, which if ignited can explode. In the present work, authors give indications for risk assessment of LPG release scenarios. The evaluation is obtained by combining the probability of the occurrence of the scenarios with the relative class of consequences of the dangerous phenomena (effects on the human target and effects on the environment target). The combination obtained through a risk matrix has the purpose of identifying the accident scenarios with the greatest impact. From matrix scenarios, we can deduce: - Phenomena with a low frequency and/or consequence that probably have no concrete effect on the damage; - Phenomena which will certainly lead to the development of real damage (these will have to be re-analysed in order to insert additional safety systems); -Phenomena of medium effect, which will probably have real effects on the damage and will be selected for further study. These scenarios for LPG depots, which fall under the activities at risk of major accident, are the basis of correct territorial planning and internal and external emergency planning; also consider the Italian Directive of the Presidency of the Council of Ministers - Civil Protection Department of 7 December 2022. (Guidelines for the preparation of the external emergency plan, guidelines for informing the population and guidelines for testing external emergency plans (Italian Official Gazette no. 31 of 7 February 2023)).
