Factors affecting anti-radiation protection and shielding performance for different metal and non metal environment friendly composite materials

The aim of this research was to design, fabricate and develop an efficient radiation shielding material to meet today's needs and to further investigate its applicability too. To attain this goal, different types of composite shielding materials such as metalreinforced rubber, heavy base metal rock ores, reinforced geopolymer concrete heavyweight shields such as tungsten-brass (W-brass) composites and high density Portland cement concrete and other multifunctional radiation shielding materials were all fabricated, examined and evaluated with a special focus on wastes and recycled materials, for instance; iron fillings, worn out steel balls and slags amongst many. Portland cement concrete and geopolymer concrete relying on heavy metal ore rocks were included too. Lead was ruled out due to its toxic nature so Green friendly materials to replace lead in shielding. The experimental work included different powder metallurgy, casting, molding to consolidate the metal, ceramics and polymer materials. Viewing the aspect of radiation attenuation and attaining the highest possible density were both the comer stone of this work. Controlling the microstructure properties as well as focusing on the type of the materials used itself was both considered to enhance density and attain the required target. Extensive gamma-ray attenuation was measured for each material at different radiation sources of different energy levels carried out in transmission geometries using gamma ray spectrometer of3"x3" Nal (Tl) detector with a Multi-Channel Analyzer (MCA). The utilized radiation sources comprised Cesium-137 (137Cs) and a Cobalt-60 (60Co) radioactive elements with photon energies of 0.662 MeV for 137Cs and two energy levels of 1.17 and 1.3 3 MeV for the 6°Co. The acquired results revealed that tremendous improvement in gamma-ray attenuation ability can be attained for the material used via controlling the microstructure parameters such as the distribution of the hard highly-dense component in the matrix, the particle size; orientation and porosity level. The attenuation level and other factors such as, the half value layer {HVL), the mean free path (Mfp), the linear attenuation coefficient~ and the standard deviation(u) a were calculated by special equations and compared with those of different material spectrum examined by other researches and related to the standard lead shield. The best attenuation coefficient ( - ) results acquired for W-pre alloy brass composite, NR/NBRr-hard particulates composite, OPC concrete and geopolymer concrete were: (1.12±0.010 cm·1 for 137Cs and 0.98±0.012 em· 1 for 6°Co), (0.0410± 3.2123x10-3for137Cs and 0.0346± 6.973x10"3 , 0.0182±1.297xi0-3 mm·1 for 6°Co), (1.102±0.263, 0.803±0.032, and 0.891±0.021 cm-1) and (0.201±0.002 for 137Cs , 0.162±0.003 cm·1 fo.-6°Co) respectively. Finally, tilting of the shield at various angles was tried to increase the traversed distance the ray has to travel within the shield and increase the attenuation accordingly. For certain tilt angles( depending on the source distance and source orientation too) attenuation value can be doubled, compared to nontilted shields attenuation.