International organization established in 1958 to form a common market for developing peaceful uses of atomic energy. It originally had six members; it now includes all members of the European Union. Among its aims were to facilitate the establishment of a nuclear energy industry on a European rather than a national scale, coordinate research, encourage construction of power plants, establish safety regulations, and establish a common market for trade in nuclear equipment and materials. In 1967 its governing bodies were merged into the European Community