Effect of radiation on immobilizer borate glasses: An examination of optical, thermal, and radiation shielding characteristics

In the present work, borate-based glass is suggested as a disposal matrix for radioactive waste generated from various nuclear energy activities. Moreover, it was proposed that doping the basic borate glass with transition metals of high molecular weight would enhance its confinement capacity for radioactive waste. To determine the optimal conditions for this study, samples of sodium borate glass were mixed with CdO instead of B₂O₃ at concentrations ranging from 0 to 45 mol% and tested for their density, UV absorbance, thermal properties, and radiation-blocking effectiveness. Results indicated a favorable correlation between density and CdO content; the transition of BO₃ into BO₄ units creates four-fold coordinated boron atoms, which results in increased density. The UV absorption spectrum displays two peaks at 240 and 380 nm, but no visible absorption bands are present at higher wavelengths. Irradiating the glass with γ-rays at doses of 25 and 50 kGy reduced the intensity of the UV peaks, affecting physical properties such as the refractive index, dielectric constant, and optical basicity, all of which increase with CdO content or exposure dose. The bandgap energy (E_g) decreased as irradiation doses and CdO content increased, making the glass network more suitable for the immobilization of radioactive waste. Radiological characteristics show that the γ-ray attenuation parameters reveal that a glass sample containing 45 mol% CdO has the highest linear attenuation coefficient across all gamma energies. Furthermore, the computed mass attenuation coefficient follows the same trend. We observed excellent agreement between measured, simulated, and estimated attenuation coefficients. It was demonstrated that thicknesses of 3.8 and 4.8 cm can reduce the gamma energies emitted from Cs-137 and Co-60 to half their intensity from the glass sample of CdO0.45. Additionally, a slight change in fast neutron removal cross-sections (FNRCs) was noted at different concentrations of CdO, with the highest value being 0.01095 cm⁻¹.