Testing of a New High-Density Concrete as Neutron Shielding Material

We present the testing as neutron shielding material of a new high-density concrete (commercially available under the name Hormirad™, developed by the Spanish company CT-RAD). The purpose of this work was to characterize the material behavior against neutrons, as well as to test different mixings including boron compounds in an effort to improve neutron shielding efficiency. Hormirad™ slabs of different thicknesses were exposed to a 241Am-Be neutron source under controlled conditions in the neutron measurements laboratory of the Nuclear Engineering Department at UPM. The original mix, which includes a high fraction of magnetite, was then modified by adding different proportions of anhydrous borax (Na2B4O7). The same experiment was repeated with HA-25 concrete slabs, looking for a reference against ordinary concrete used to shield medical accelerator facilities. In parallel to the experiments, Monte Carlo calculations of the experiments were performed with MCNP5, with some differences found, attributable to uncertainties in the elemental composition of the samples tested. The first and equilibrium tenth-value layers have been determined for the different types of concrete tested. The results show an advantageous behavior of the Hormirad™ one, when comparing neutron attenuation against real thickness of the shielding. Although borated-concretes show a little better neutron attenuation with respect to mass-thickness, the resulting reduction in density and structural properties makes them less practical.