ANALYSIS OF THE MISSILE IMPACT ON NUCLEAR POWER INSTALLATIONS

The Ukraine-Russia war rekindled the attention and concern for the threats caused by the external man-induced events. Particularly, great concerns arise for the integrity of the nuclear facilities, safety and security systems, power supply, etc. The missile impact on NPP aged may determine an extensive damage and, in the worst case, the partial or total collapse of buildings. The aim of this study is to determine numerically the ballistic resistance of reinforced concrete/armor materials to penetration by defining a scabbing threshold. A 3D finite element (FE) model of the nuclear building where the spent fuel pool is located, was implemented considering different types of models for wall perforation and velocity perforation and assuming cylindrical shape for the projectile. Plasticity-based material damage was also assumed. Results show that at the instant of the impact, an intense shock wave is initiated in the projectile and target causing the fracture or flow of materials. The residual debris expands as a “bubble” behind the impacted wall and some fragments are seen in front of the surface. For thin wall as the impact velocity increases, damage modes progress for simple dimple formation to spallation, and perforation. Thermal degradation determines a further reduction of the structural integrity.