Assess of the Nuclear Power Plant Structures Residual Life and Earthquake Resistance

The paper deals with the seismic analysis of safety related structures of an operating nuclear power plant. At present time the nuclear power plants of VVER-400/213 type operate for over thirty years and there are arising requirements to verify the actual state of structures in order to assess their residual life in general. A sophisticated computation model has been developed for the seismic structural analysis using the ANSYS program package. The model involves the complex of all constrained structures of two main production blocks with equipment. In order to get a general view at the seismic load effects, seismic response analysis has been performed using direct integration of equations of motion in 25 sec interval at 0.01 sec step with excitation described by accelerograms. Combinations of dead loads and seismic loads have been considered in the stress assessment of the structures. The results of the performed analyses form a base for residual life prediction of selected structures