The standardization of nuclear plants offers considerable advantages and results in particular in a reduction in deadlines and costs and in a concentration of the studies and testing facilities on a single type of equipment. In order that this standardization be even more beneficial, Electricité de France and Spie-Batignolles Company have developed the aseismic bearing foundation system based on the combination of elastomer and friction elements. This system permits the reconduction of a standardized nuclear plant in potentially higher seismic areas with an equivalent or even higher degree of safety. The implementation of this concept on actual nuclear power plants has necessitated a comprehensive analysis of technological and mathematical aspects during recent years.