The 12th International Conference On Emerging Nuclear Energy Systems that was organised in Hotel Metropole, Brussel, August 21-26, 2005 by SCK•CEN, the Belgian Nuclear Research Centre. The main objective of ICENES 2005 was to provide an international scientific and technical forum for scientists, engineers, industry leaders, policy makers, decision makers and young professionals who will shape future requirements, for a broad review and discussion, at world level, of various advanced, innovative and non-conventional nuclear energy production systems. The proposed systems should contribute to a sustainable development of future energy production. Earlier editions were held in Graz (Austria), Lausanne (Switzerland), Helsinki (Finland), Madrid (Spain), Karlsruhe (Germany), Monterey (USA), Chiba (Japan), Obninsk (Russia), Tel-Aviv (Israel), Petten (The Netherlands) and Albuquerque (USA) respectively. Over 110 participants from over 21 different countries participated in our Conference. During the five days that the Conference lasted, a total of 68 papers were presented. 55 of them were presented during 14 oral sessions and 13 during the 2 poster sessions.