Gamma-ray and charged-particle shielding properties of W–Ni–Fe heavy alloys

Tungsten-based heavy alloys are promising lead-free candidates for advanced radiation shielding due to their high density and atomic number. In this study, the photon and charged-particle shielding performance of tungsten–nickel–iron (W–Ni–Fe) alloys containing 85–98 wt% tungsten was systematically investigated over a wide energy range (0.01–10 MeV for photons). Mass attenuation coefficients ( µ/ρ ) were calculated using the WinXCOM database and independently evaluated using Monte Carlo simulations performed with MCNP6 and PHITS under narrow-beam geometry. The deviations between the computational methods remained below approximately 3%, demonstrating good consistency among the adopted approaches. Based on these results, key shielding parameters including linear attenuation coefficient (µ), half-value layer (HVL), tenth-value layer (TVL), mean free path (MFP), and effective atomic number (Z eff ) were determined. In addition, exposure and energy absorption buildup factors (EBF, EABF) were evaluated using EpiXS, while Kinetic Energy Released per Unit Mass (KERMA) values were calculated relative to air, concrete, and water. Charged-particle shielding performance was assessed by calculating mass stopping power (MSP) for protons and alpha particles using SRIM. The results demonstrate a strong energy dependence governed by dominant photon interaction mechanisms (photoelectric effect, Compton scattering, and pair production). Increasing tungsten content significantly enhances photon attenuation, leading to higher µ and µ/ρ values and reduced HVL, TVL, and MFP. Among the investigated alloys, W98NiFe exhibited the best overall photon shielding performance, whereas alloys with lower tungsten content showed relatively higher stopping power for charged particles in specific energy regions.