Results in Physics (Jun 2022)
Comparative assessment of fast and thermal neutrons and gamma radiation protection qualities combined with mechanical factors of different borate-based glass systems
Abstract
Adequate shielding from ionizing radiations is essential in nuclear facilities because of such radiations’ adverse effects on humans in the event of unwanted or accidental exposure. In the current work, for four distinct compositions of B2O3-Li2O, Li2O-Na2O-K2O-B2O3, Gd2O3-SiO2-B2O3, and Bi2O3-Li2O-ZnO-B2O3 glass systems, neutron and γ-ray attenuation competencies combined with elastic features have been examined for feasible nuclear radiation protection purposes. ΣR (fast neutron removal cross-section) and for thermal energy neutrons σT (total cross-section) and SP (shielding percentage) were estimated. Comparably, in all samples, 50B2O3-10K2O-40Li2O (mol%) glass possesses larger ΣR (=0.11755 cm−1), whereas 25B2O3-37.5Si2O-37.5Gd2O3 (mol%) glass shows large σT (=646.171 cm−1) and SP for thermal neutrons at minimal thickness, indicating the included Gd2O3’s positive effect as element Gd has a high neutron absorption capacity. Employing the Phy-X/PSD program and MCNPX code, μ/ρ (mass attenuation coefficient) of all selected glasses is calculated for a γ-ray energy span of 0.015 – 15 MeV. Gd2O3 or Bi2O3 addition improved μ/ρ, and such increment is significant at low energies owing to PEA (photoelectric absorption) dominance and Gd or Bi K-edges. Also, for 15B2O3-10ZnO-5Li2O-70Bi2O3 (mol%) glass, μ/ρ has been derived by the WinXCOM program and FLUKA, Geant4, and PHITS codes, and a good accord between such simulated and theoretical μ/ρ outcomes is noticed following the calculated relative differences. Next, linear attenuation coefficient, effective atomic number and electron density, MFP (mean free path), TVL (tenth-value layer), HVL (half-value layer), and RPE (radiation protection efficiency) have also been evaluated. Comparatively, at 1.25, 0.662, and 0.2 MeV energies, 15B2O3-10ZnO-5Li2O-70Bi2O3 (mol%) sample possesses lower MFP and HVL than five SCHOTT AG commercial glass shields. Approximated RPE results affirmed all Gd2O3-SiO2-B2O3 and Bi2O3-Li2O-ZnO-B2O3 samples’ potent absorption (almost 100%) ability for lower energy γ-rays. Moreover, equivalent atomic number, and by geometric progression fitting process, within energy 15 keV–15 MeV extent for ten different penetration depths at 1–40 mfp span buildup factors have been assessed. 15B2O3-10ZnO-5Li2O-70Bi2O3 (mol%) glass exhibits better gamma-ray shielding effectiveness in all chosen samples, specifying Bi2O3’s favorable impact. Changes in photon shielding factors were interpreted following pair production, Compton scattering, and PEA processes. Later, elastic (Young’s (Y), bulk (K), shear (S), and longitudinal (L)) moduli and Poisson’s ratio values have been calculated for all inspected glasses. BC (bond compression) and M-M (Makishima–Mackenzie) models were utilized for such elastic traits reckoning. All K, Y, S, and L values’ trends for binary B2O3-Li2O glasses were identical in both BC and M-M models, and Kbc was found to be raised from 73.63 to 89.89 GPa, while KM–M increased from 75.35 to 180.53 GPa accordingly when Li2O content improved from 9.6 to 39.9 mol% in the chemical composition.
