Speakers
Description
The Laboratori Nazionali del Sud (LNS) of Italian National Institute for Nuclear Physics (INFN) is a facility devoted to research activities in the field of Nuclear Physics, Nuclear and Particle Astrophysics, but also of Applied research, such as medicine, cultural heritage, and industry. The main particle accelerators are a K800 Superconducting Cyclotron (CS) and an electrostatic 16 MV Van der Graaf Tandem. Some LNS concrete shields of experimental rooms have been demolished due to an upgrade of the Cyclotron. The shields could be radioactive because was exposed to ambient neutron fields generated by the experiments carried out during the last 30 years of LNS activity. To dispose of concrete, measurements and estimations of residual radioactivity have been carried out to verify the clearance levels.
In order to verify the radioactivity quantity, gamma-emitting, some measurements were carried out with a HPGe detector. Furthermore, to estimate the presence of pure beta-emitting radionuclides, impossible to be detected by HPGe, and to confirm the measurements made for the gamma-emitting radionuclides, we simulate a simplification of the last 30 years experiments using the code of calculation Monte-Carlo FLUKA. Moreover, to determine the Minimum Detectable Activity (MDA) for the HPGe measurements and to confirm the reliability of simulation, a sample of concrete identical to the demolished one was prepared and irradiated with a high intensity field of a known Am-Be source.
The results, even in the worst condition of the CS beams, evidence that the concrete is in conditions of no radiological relevance and could be disposed of. In this work we present the performed simulations and the measurements.