Integrating Experimental Measurements, WinXCom Calculations and Monte Carlo Simulations to Evaluate the Ionizing Radiation Shielding Performance of UPR/Bi2WO6 Nanocomposites

Lead-free polymer nanocomposites have attracted considerable attention as sustainable alternatives for ionizing radiation shielding. In this study, unsaturated polyester resin (UPR) nanocomposites containing hydrothermally synthesized Bi2WO6 nanoparticles (2.5–10 wt.%) were fabricated, and their gamma-ray shielding performance was evaluated experimentally and theoretically. The structural and morphological properties of the nanoparticles were characterized by XRD, FTIR, and FESEM. Mass attenuation coefficient (MAC), half-value layer (HVL), and mean free path (MFP) were experimentally determined at photon energies of 81–1332 keV and validated using WinXCom calculations and MCNP6.3 Monte Carlo simulations. In addition, the effective atomic number (Zeff) and effective electron density (Neff) were calculated over the energy range of 0.001–100 MeV. Increasing the Bi2WO6 content enhanced the MAC, Zeff, and Neff values while reducing the HVL and MFP, indicating improved shielding efficiency. The composite containing 10 wt.% Bi2WO6 exhibited the highest attenuation performance, achieving an MAC of 0.4638 cm2 g−1 at 81 keV. The maximum deviation between experimental, theoretical, and simulation results remained below 2.8%, demonstrating excellent agreement. These findings identify Bi2WO6-reinforced UPR nanocomposites as promising lightweight, lead-free materials for gamma-ray shielding applications.