Global Structural Response of an SMR Reactor Subjected to an Aircraft Impact

Although a 11 September 2001-style vicious attack on a nuclear power plant is considered as ‘beyond design basis’ event, an appropriate design of the nuclear facilities, with features and functional capabilities, is of meaningful importance to demonstrate that the reactor containment could safely withstand the impact of a large commercial aircraft without any radioactive release. This paper deals with the evaluation of the global structural response and of the vulnerability of a reactor building subjected to a deliberate commercial aircraft impact in the assumption of an attack from multiple entry directions. In this framework, separately from penetration and fire, the ‘shock’ loadings due to the progressive aircraft crashing on the power plant buildings were evaluated, taking into account that even if such penetration occurred, together with some concrete crushing and bent steel rebars, it very probably would not reach the reactor vessel. To the purpose a rather refined numerical methodology was employed and three-dimensional models (FEM approach) of a SMR reactor building and possible realistic, even if simplified, aircraft structures were set up and used in the performed analyses, taking also into account a suitable materials behaviour and constitutive laws. The analysis was performed increasing the severity of the crash scenario, assuming that the during the impact the aircraft transfers the full impact energy of the crash to the structure being struck. The obtained results were analysed to check the additional safety margin of the reactor containment and the fuel pool.