[en] The globalization phenomenon and the process of regional integration have generated new and defiant characteristics in the criminal activation, the one that has acquired growing trans national dimension. After September 11, 2001 it should to have bigger international initiative to reinforce the safety of materials and facilities in the entire world and to apply the international recommendations for to assure that all the nuclear materials of not used bombs are registered and secure of sabotage. Thousands of radioactive sources exist in the world. Possibility that the terrorists use radioactive sources as attack instruments since its are more easily available and its are more easy too to obtain in comparison with the uranium or plutonium classified for weapons. Dirty bomb. Effects of the Radiations. The Goiania accident. 'Orphans' sources Illicit traffic of radioactive material. Security. Measures of Physical Protection. Security of the radioactive sources. Role of the IAEA and other international organisms and regional CAN-MERCOSUR. Nuclear security and Legal frame. International and national instruments against the nuclear and radiological terrorism. Study from a proposal to Pan-American level to make in front of the problem. (Author)