Abstract: A mechanism for anti-seismic connection between the pump base and the dome of a nuclear power station is characterized by the fact that the pump base (1) is equipped externally with a flange (3) seated with a slight axial play and significant radial play within a socket (4) which is a fixed cover closed by and able to slide axially with a slight play within a cylindrical reinforcement (7a) of the dome (7). A radial damping mechanism (8) is installed between the flange (3) and the socket (4) to permit slow displacements between these two entities, but to block abrupt displacements. The lower end of the socket (4) comprises a collar (15) equipped with a metallic journal (16) which can slide axially within a bearing (17) firm with the internal wall of the dome (7).