Large airplane crash on a nuclear plant: Design study against excessive shaking of components

摘要

The problem of the strong shaking of structures and of components in case of an aircraft impact is the subject of this study. This problem is solved in some designs by protecting the external Nuclear Island block (N.I.) by an external thick wall, capable to withstand the aircraft impact. This wall is connected to the rest of the N.I. by the common foundation slab only. The first part of this study consists of the evaluation of the order of magnitude of the vibration attenuation which can be obtained by this design scheme. Should the attenuation obtained be not sufficient for some parts of the internal structures, some additional design provision could be adopted. In order to solve this problem, a specific design solution is here suggested. It essentially consists in connecting critical parts of structures to the common foundation slab with restraints having an adequate degree of deformability, so that the transmission of high frequency impact forces from other parts of the whole structure is minimized. In a previous paper (Petrangeli, 2007), the structural protection of the reactor dome and of connected structures of a modern nuclear plant is dealt with. In the present paper, the protection of internal parts of the plant (the internal containment is chosen) in case of strong impact on lateral walls is studied. The indicative result of this study is that the enhancement of attenuation in the transmission of acceleration from the impact point to some representative point in the inner structure is of the order of 75. This result cannot be generalized, as it depends on many parameters of the structure and of the soil.