Experimental and numerical analysis of the fragility of the bubble tower structures under extreme pressure and temperature

This paper describes the experience from the experimental and numerical analysis of the hermetic tightness of bubble tower (BT) of the nuclear power plant (NPP) type VVER 440 under the high internal overpressure after 30 years of the performance. The results from the experimental tests were used for the verification of the numerical model of the reinforced concrete structures. There is showed summary of calculation models and calculation methods for the probability analysis of the structural integrity due to extreme overpressure. The tightness testing of the steel internal liner during the NPP performance was realized in accordance of the international standards. The methodology of the probability nonlinear analysis of the concrete structures using new model of the layered shell elements considering the process of the concrete cracking and crushing.