Due to the high inertia of the metal coolant, the safety concerns of the next generation LMRs (e.g. the Advanced Lead Fast Reactor European Demonstrator - ALFRED) have some connections with the core compaction phenomenon when severe earthquake occurs. In this paper the effects on the fuel assemblies (FAs) are numerically analyzed (by FEM code) taking into account suitable boundary and initial conditions. To characterize the interaction between the internal components, surface-to-surface contact condition has been implemented.
The results indicate that the annular area neighboring the piping penetration ovalizes and so a circumferential buckling occurs. The FAs undergo bending deformation especially in correspondence of the half height of the elements. The displacement varies along the vertical axis (direction of maximum flexibility) reaching, in some time interval, the maximum value of about 9 cm. Vibration phenomenon also appeared.