Detection and characterization of neutron activation activities using gamma spectrometric analysis

Neutron activation analysis (NAA) of environmental samples is normally performed using research reactors. IAEA inspectors collect swipe samples at such reactors to verify that undeclared irradiation activities have not been carried out. High resolution gamma spectrometry (HRGS) analytical results of the collected swipes may identify signatures which indicate irradiation activities have been performed at the reactor. The modelling of typical irradiation scenarios used for NAA of material with known elemental composition, followed by the comparison of the calculated activities with the HRGS measurement results of the swipe, allows for the identification of the approximate irradiation date and the type of irradiated material present on the swipe. This approach has been applied for identifying signatures of NAA of soil samples. (author)