Evaluation of safety performances of a superficial disposal facility subject to an aircraft impact and fuel burning

Safety and security aspects are of meaningful importance in the design of nuclear facilities. In this study, the attention is so focused on the potential damaging effects that a large civilian airplane impact could bring in safety relevant structures, like a superficial repository similar to El Cabril one. Safety performances of such a type of superficial disposal facility, subjected to the aircraft impact and fuel burning, have been analysed and discussed. Conservative assumptions have been made: normal impact on the lateral repository surface, fire scenario based on the amount of fuel burnt. Load functions (calculated with the Riera approach) and the maximum temperature reached by fuel during its combustion were used as input (boundary condition) in the numerical simulations as well as the damaging phenomena occurring in the concrete structure. Numerical analyses, by MARC© code, allowed to simulate the thermo-structural performances of the superficial repository. The obtained results showed that a repository wall thickness, ranging from 0.6 to 0.9 m, is not sufficient to prevent the penetration of wall itself. Despite the ongoing concrete degradation phenomena, the global strength of the repository seemed to be guaranteed.