Gamma-Ray Spectrometric Investigation of Rare-Earth-Doped Glasses Irradiated by Fast and Thermal Neutrons

In the current study, four borate glass samples were fabricated according to the chemical formula of 20Na2O-69B2O3-10ZnO-1RE, where the rare earth (RE) is CeO2, Pr2O3, Nd2O3, and Er2O3, all in mole percent. Utilizing a TESCAN Mira3 scanning electron microscope featuring an energy-dispersive X-ray analysis for characterization, the elemental chemical composition of the prepared samples was measured. In order to analyze the secondary gamma-ray emission from the prepared samples, they are irradiated with high doses of fast and thermal neutrons. The irradiation process was performed by placing the prepared samples within a dry channel of the nuclear reactor IVV-2 M core for 4 h. The flux density of thermal neutrons is 8156 × 1012 n/(cm2.s), and it is 8.11 × 1011 n/(cm2.s) for the fast neutrons. Then, the secondary gamma-ray emission from the irradiated glasses was detected using a CANBERRA high-purity germanium detector. The spectrometric analysis confirms the presence of many radioactive isotopes due to the activation of the glass-constituting elements. The dose rate (µSv/h) at a distance of 1 m from the irradiated samples reached 116.9, 150.5, 95.2, and 95.5 µSv/h, respectively, when the glass samples were dosed with 1 mol % of CeO2, Pr2O3, Nd2O3, and Er2O3, respectively. Owing to the elevated dose rates, the manufactured samples are not safe for direct handling postirradiation; they must be stored in shielding containers for 10 days prior to handling. After this period, the dose rates at a distance of 1 m from the samples CeO2, Pr2O3, Nd2O3, and Er2O3 are reduced to 0.027, 0.031, 0.012, and 0.190 µSv/h, respectively.