Specific induced activity profile at the rotary specimen rack of IPR-R1 TRIGA reactor

The IPR-R1 TRIGA nuclear reactor at Nuclear Technology Development Center, CDTN/CNEN, Belo Horizonte, Brazil, has a rotary specimen rack, RSR, outside the reactor core, and it is composed for forty irradiation channels in a cylindrical geometry. The aim of this work is to evaluate the neutron fluence rate distribution at the RSR and its variation under different irradiation conditions by means of specific induced activity measurements. Al-0.1 % Au reference materials were irradiated simultaneously at 100 kW in these irradiation channels and gamma spectrometry was applied with HPGe detector to determine the specific induced activity. This procedure was repeated six times. The results show an asymmetrical neutron fluence rate distribution at the RSR. The variation between the minimum and the maximum specific induced activity values in the RSR channels is about 14%.