Effect of thermal neutron flux on borate and silicate glasses: Experimental and theoretical investigation for distribution, decay period, and absorbed dose rate of produced isotopes

The gamma-ray shielding properties for silicate and borate glass samples were enhanced by heavy metal oxides such as Bi₂O₃, CdO, and Y₂O₃. The current work aims to study experimentally performance of these borate and silicate glasses experimentally when exposed to a flux of thermal neutrons. A nuclear research reactor was utilized to irradiate the fabricated glasses with various doses of thermal neutrons varied between 1.73 and 12.10 MGy. Additionally, the fluency of the thermal neutrons within the dry channel of the IVV-2M reactor containing the fabricated samples varied between 2.27E+17 and 15.86E+17 neutron/cm² at various irradiation times between 1 and 7 days. After that, a gamma-ray spectrometer was utilized to detect the activity concentrations from the irradiated glasses as well as identify the new isotopes created within the fabricated glasses. Additionally, the Monte Carlo simulation code was utilized to estimate the absorbed dose from the irradiated glass samples over a time period between 1 and 120 days after the exposure. The study shows almost all of the activities of the irradiated samples decomposed over 80 days after irradiation. The decomposition of the dose rate and activity concentration for the irradiated samples are attributed to the short lifetime of Ba-131 isotope which represents the major radioactive isotope created within the glass sample.