Characterization of unknown objects containing radioactive materials

Fraunhofer INT is going to equip a transportable container with a system for the detection, identification and characterization of radioactive material inside objects with unknown content. This system will be a prototype for a mobile system to detect illicit trafficking of radioactive and especially nuclear material and will thus prohibit nuclear proliferation. This container will be equipped with systems for passive and active nondestructive measurements. For active measurements we use a sealed tube 14 MeV neutron generator with and without a moderating assembly between the interrogating neutron source and the object of interest. Because stolen or diverted radioactive material generally may not have a fixed geometry and will not be packaged in standard containers the main emphasis in this paper is on in-situ gamma measurements taking into account possible shielding around the radioactive source. High-resolution gamma measurements were performed on radioactive material behind differen t types of shielding. The measured data were evaluated by modeling the different parameters like the wall thickness of the box, matrix and shielding material inside and so on. Comparison with the actual experimental setup of the models showed good agreement and proved the power of this method. In this way significant information was gained on the content of the unknown box, with is important for further actions