The first Chooz B nuclear power plant, an N4 1400-MW pressurized water reactor scheduled for commissioning in 1992, represents an important step in the French nuclear program. For its construction, an integrated computer-aided design system has been set up by Electricité de France. Such a system was necessary because of the development of new microprocessor-based technologies. Indeed, this is the only way to provide consistent mechanical, electrical, and instrumentation and control data, and thereby achieve a high quality level.