This article discuss an analytical dynamic model of a polar crane to assess its seismic strength based on artificially generated accelerograms. The polar crane is installed under the dome of the VVER-1000 NPP containment and serves to move various cargoes in the reactor compartment, including nuclear hazardous cargo. The high-rise location of the crane (+ 55m) causes the possibility of significant seismic loads. To build a dynamic model, at the beginning, the stiffness of individual elements was analyzed using numerical and analytical methods. In particular, the stiffnesses of the main beams and the main balancers are analyzed to determine the type of dynamic model required. A feature of the seismic analysis of a polar crane is the nonlinear interaction of its elements, which can lead to the breaking of some connections and the separation of the structure from the supporting elements. The key in the analysis is taking into account the contact nonlinearity of the wheel-rail pair; to model this contact, we used the classical theory of Hertz. The generalized response spectra for the NPP site were used as the load. A method for calculating artificial accelerograms, which are generated for the purposes of dynamic analysis, based on response spectra is used. Also, as a comparison, the results of calculating the seismic strength of the polar crane by the linear response spectrum method are given. As a result of the analysis, weak points in the structure were identified, and the ultimate seismic resistance of the polar crane was determined.