Enhanced neutron and gamma shielding via optimized hematite/B4C ratios in concrete: A combined experimental-simulation study using laboratory radioactive sources

This study experimentally and by Monte-Carlo simulation evaluates the gamma-ray and neutron shielding ability of 51 concrete composites incorporating various hematite (Fe 2 O 3 ) concentrations as aggregate replacement and boron carbide (B 4 C) as an additive. The total neutron macroscopic cross-section (Σ n ) for an Am-Be source and the linear gamma attenuation coefficient (μ γ ) for 137 Cs and 60 Co gamma sources (661.66, 1173, and 1332 keV) were measured and compressive strength (CS) was also determined for all concrete shield samples. The results show that hematite significantly increases the photon and neutron attenuation ability due to its high thermal neutron's cross-section and higher atomic density compared to conventional aggregate. By increasing the hematite concentration to 70%, the performance of the concrete shield reaches saturation. Furthermore, Gamma attenuation efficiency predictably decreased with increasing energy. The results also indicate that increasing hematite concentrations in aggregates beyond its critical level at a concentration of 50% leads to a decrease in compressive strength. While B 4 C addition improved neutron attenuation, it inversely affected CS and μ γ . Composites containing 40% to 50% hematite exhibit the best performance for μ γ , Σ n , and CS simultaneously. Using H 50 -B 20 composite instead of ordinary concrete reduces the gamma tenth-value layer by ∼57% and the neutron tenth-value layer by ∼45%, and also increases the CS by ∼85%. This significant improvement in the effectiveness of the concrete shielding highlights the potential of these composites to increase volumetric efficiency and useable space in nuclear facilities, while reducing the need for construction materials and enhancing structural resistance.