QUANTITATIVE RISK ASSESSMENT APPLIED TO SPES FACILITY

The SPES Radioactive Ion Beam (RIB) facility is in the construction phase at INFN-LNL. SPES is the acronym for “Selective Production of Exotic Species”. The aim of the SPES project is to provide high intensity and high-quality beams of neutron-rich nuclei to perform forefront research in nuclear structure, reaction dynamics and interdisciplinary fields like medical, biological and material sciences. It is based on the ISOL method with an UCx Direct Target able to sustain a power of 10 kW. The primary proton beam is delivered by a Cyclotron accelerator with an energy of more than 40 MeV and a beam current of 200 µA. Neutron-rich radioactive isotopes will be produced by Uranium fission at an expected fission rate in the target of the order of 1013 fissions per second. Currently work is underway to complete the infrastructures and the security system of the SPES building, which are binding for the issue of the CPI (Fire Prevention Certificate) and the necessary authorizations relating to the radiological risk. It is necessary to develop reliable methodologies to analyse, from a safety point of view, the dynamic behaviour of the characteristic mechanisms of a system which can include system errors, events from the sequence of operation, spare parts and variation of the failure rate of the compound functioning at high levels of radiation. Through the dynamic study of a system considering these factors, it is possible to obtain frequencies of occurrence of accidental events starting from failure rates that are more representative of reality, especially as regards a complex system such as SPES. In terms of fire safety, therefore, there is the problem of extinguishing a possible outbreak, despite the reduced possibility that a fire could develop inside the basement of the building, given that most of the material present in the bunker is self-extinguishing and flame retardant. The goal, through the FDS modelling, is to determine whether, in the event of a fire, this remains confined within bunker and pre-bunker or whether there is a leak of radioactive fumes. Taking in to account this result of the simulation it is necessary to develop the internal and external emergency plan; the instruction manual for exceptional situations (identification of rescue teams, PPE and necessary equipment); the activities, programs and measures to be implemented from the beginning of the risk scenario until the arrival of the rescue teams; the training programs also for the external rescuers team (Fire Brigade, SUEM).