Experimental and Numerical Analysis of the Hermetic Tightness of NPP Bubble Tower Structure

This paper describes the experience from the experimental testing 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 checking of the numerical model of the reinforced concrete structures. There is showed summary of calculation models and calculation methods for the reliability 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 and results of the optical and mechanical measure are presented. On base of the nonlinear analysis the safety and reliability of the concrete structure were considered.