Structural Vibrations in a Building of a Nuclear Power Plant Caused by an Underground Blasting

In this paper, a methodology has been proposed to obtain the response spectrum of a nuclear building caused by underground detonations. For the problem at hand, a reinforced concrete building containing a boiling water reactor was postulated. It was constructed on a hard soil with a zero-period acceleration of 0.26 g. Its structural damping was 7%. The building is subjected to horizontal vibrations originated from a detonation of 15 tons of TNT, located at a distance of 2000 m from the nuclear power plant site. Initially, an analytical evaluation was carried out to obtain the horizontal vibrations. In a second step, a foundation soil model was developed with the finite element method in conjunction with an explicit approach. ANSYS^® Autodyn^® code was used. The response spectrum due to the underground detonation was developed with the data obtained. It was compared with the safe shutdown earthquake (SSE) response spectrum and the operating basis earthquake (OBE) response spectrum. The results show that the seismic response spectrums envelop the explosion response spectrum. A resonance did not develop. The horizontal velocity is below the limits established by the regulations considered in this paper. Under this condition, the postulated building is safe.