Neutron and Gamma Radiation Shielding Block from Natural Rubber

Abstract

A neutron and gamma radiation shielding block is developed based on natural rubber mixed with boron compounds and lead oxide. In this study, two types of boron compounds, including borax and boric acid, are considered. This shielding block is exposed to the radiation from an ²⁴¹Am/Be radiation source. It is found that both types of the rubber shielding blocks can efficiently reduce thermal neutron, where its efficiency increases with the thickness and boron concentration. Although the amount of boron per weight of boric acid is higher than that of borax, the radiation shield efficiency of the rubber shielding block mixed with borax is higher. This can be explained by the increase of porous structure in rubber shielding block mixed with boric acid, resulting in the decrease of boron concentration per volume in the rubber shielding block mixed with boric acid. In addition, lead is mixed into the rubber shielding block to absorb the gamma ray radiated from the neutron absorption. It is found that the rubber shielding block with boron compound and lead can efficiently absorb both neutron and gamma radiation.  Furthermore, the decrease of physical properties of the rubber shielding block, including hardness, tensile strength, and elongation at break, is also found.