Investigation of Photon Radiation Attenuation Capability of Different Clay Materials

Alkaline saline lakes: A chemical evolution experiment evaluating the stability of formaldehyde in an aqueous saline environment

Formaldehyde condensation in the presence of a mineral catalyst and under alkaline conditions is considered to be a "messy" chemical system due to its dependence on the complex chemical equilibrium between the reaction intermediates, which has a significant impact on the final products. This chemical system is extremely important in prebiotic chemistry and has been proposed as a potential pathway for carbohydrate formation in the early Earth. Saline and soda lakes are alkaline systems that could concentrate and accumulate a wide variety of ions (such as phosphate) and clay minerals, which can catalyze prebiotic chemical reactions. These geological environments have recently been suggested as ideal environments in which prebiotic chemical reactions could have occurred. This study uses Lake Alchichica in Mexico as a physicochemical analog of an early Archean saline lake to examine the stability of formaldehyde in these aqueous saline environments. Formaldehyde decomposes into sugar-like and CHO molecules in alkaline, high-salinity environments depending on the minerals phases present. As phosphate ion (HPO4 2-) is available in the aqueous medium, the results of our experiments also imply that phosphorylation processes may have occurred in these natural settings.

Radioactive Attenuation Using Different Types of Natural Rocks

Humans benefit from nuclear technology, but it also generates nuclear radiation that is bad for both the environment and human health. The serious issue of radiation leakage affects many technological applications. Shielding is required to protect both users and the environment from negative side effects. This work describes the radioactive attenuation properties of some natural rocks, such as claystone, bentonitic claystone, bentonitic shale, sandstone, and basalt using a NaI(Tl) detector. The mass attenuation coefficients μm of these rocks at various photon energies, half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP) were determined. The validation of obtained values of μm was carried out against the theoretical calculations from the XCOM program, and the correlation factor and relative deviation between the two methods were evaluated. It was noted that basalt samples exhibit superior shielding parameters when compared to other rock samples. Also, the concentrations of naturally occurring radioactive elements (238U, 226Ra, 232Th, and 40K) were measured, allowing for the calculation of environmental hazard indices and assessment of attenuation (%) efficiency for certain natural rocks, such as bentonite, sandstone, and basalt. The results revealed that increasing the thickness of Basalt-AZ from 1.5 cm to 2 cm results in an approximate 11% rise in attenuation percentage, with values reaching 77.12%, 67.2%, 67.65%, and 59.8% for NMA-U, IAEA-Th, IAEA-Ra, and IAEA-K, respectively.

A comparative neutron and gamma-ray radiation shielding investigation of molybdenum and boron filled polymer composites

This work presents a detailed radiation shielding study for polymer composites filled with Boron and Molybdenum additives. The chosen novel polymer composites were produced at different percentages of the additive materials to provide a proper evaluation of their neutron and gamma-ray attenuation abilities. The effect of additive particle size on the shielding characteristics was further investigated. On the gamma-ray side, simulation, theoretical and experimental evaluations were performed in a wide range of photon energies varying from 59.5 keV to 1332.5 keV with help of MC simulations (GEANT4 and FLUKA), WinXCOM code, a High Purity Germanium Detector, respectively. A remarkable consistency was reported between them. On the neutron shielding side, the prepared samples produced with nano and micron particle size additives were additionally examined by providing fast neutron removal cross-section (Σ_R) and the simulated neutron transmissions through the prepared samples. The samples filled with nano sized particles show better shielding capability than the one filled with micron sized particles. In other words, a new polymer shielding material that does not contain toxic content is introduced: the sample codded N-B0Mo50 exhibits superior radiation attenuation.

Insights into the Effect of Aggregate Sizes on the Soil Radiation Interaction Properties Based on X-ray Fluorescence

Soils subjected to disaggregation can break into aggregates of different sizes composed of sand, clay, and silt particles. Each aggregate contains different oxides, which can vary according to the aggregate size and influence its properties, such as the radiation interaction parameters. These parameters are relevant in the evaluation of radiation shielding and soil physical properties. Thirteen tropical/subtropical soils of contrasting textures (clayey and loamy/sandy) with two aggregate sizes (2-1 mm and <45 μm) were studied. The radiation parameters analyzed were the atomic (σ_A), electronic (σ_E), and molecular (σ_M) cross-sections; the effective atomic number (Z_eff); and the electron density (N_el). We verified that the aggregate sizes affected the major oxides (SiO₂, Al₂O₃, Fe₂O₃). In general, the attenuation coefficient and Z_eff were sensitive to the clayey soils' aggregate sizes (low photon energies). However, the loamy/sandy soils did not exhibit differences among the parameters. As the photon energy increased, only Z_eff presented differences for most soils. We also verified that σ_M, Z_eff, and N_el were the most sensitive parameters to the soil composition. Although the soil chemical composition was influenced by the studied aggregate sizes, the radiation parameters exhibited differences for only some of these parameters. This means that the aggregate size is practically irrelevant when radiation parameters are determined based on X-ray fluorescence.

Morphological and Gamma-Ray Attenuation Properties of High-Density Polyethylene Containing Bismuth Oxide

For extensive radiation exposure, inventing a novel radiation shielding material is a burning issue at present for the purpose of life saving. Considering this thought, in this study, by adding sundry amounts of Bi₂O₃ into pure high-density polyethylene (HDPE), six HDPE systems were prepared to evaluate the radiation shielding efficiency. These HDPE systems were HDPEBi-0 (pure HDPE), HDPEBi-10 (10 wt% Bi₂O₃), HDPEBi-20 (20 wt% Bi₂O_3-), HDPEBi-30 (30 wt% Bi₂O₃), HDPEBi-40 (40 wt% Bi₂O₃), and HDPEBi-50 (50 wt% Bi₂O₃). The values of the linear attenuation coefficients of the experimental results (calculated in the lab using HPGe) were compared with the theoretical results (obtained using Phy-X software) at 0.060, 0.662, 1.173, and 1.333 MeV energies. To ensure the accurateness of the experimental results, this comparison was made. It was crystal clear that for energy values from 0.06 MeV to 1.333 MeV, all the experimental values were in line with Phy-X software data, which demonstrated the research setup's reliability. Here, the linear attenuation coefficient (LAC), and mean free path (MFP) shielding parameters were assessed. At the energy of 1.333 MeV, sample HDPEBi-0 showed an HVL value 1.7 times greater than that of HDPEBi-50, yet it was 23 times greater at 0.0595 MeV. That means that for proper radiation protection, very-low-energy HDPE systems containing 10-50% Bi₂O₃ could be used; however, the thickness of the HDPE system must be increased according to the energy of incident radiation.

Shielding Properties of Epoxy Matrix Composites Reinforced with MgO Micro- and Nanoparticles

The aim of the current study is to investigate the impact of introducing micro- and nanoparticle MgO as a filler into epoxy resin on the radiation shielding abilities of the prepared samples. To this end, we performed a gamma-radiation spectroscopy experiment with the help of an HPGe detector and Am-241, Cs-137, and Co-60 sources. We evaluated the particle size effect (PSE) and detected the maximum PSE value with the addition of 50 wt% MgO particles, indicating that nanoparticle MgO was more successful in shielding against incoming radiation than microparticle MgO. We compared the half-value layer (HVL) for the samples with 10 wt%, 20 wt%, and 30 wt % micro-MgO and nano-MgO and found that the HVL values were lower for the nanoparticle samples than for the microparticles samples, confirming that smaller particle sizes enhanced the shielding ability of the samples against radiation. The MFP results showed that epoxy matrices containing micro-MgO, for all investigated energies, resulted in higher MFP values that those containing nano-MgO.

Impact of WO3-Nanoparticles on Silicone Rubber for Radiation Protection Efficiency

Silicone rubbers are a good choice for shielding materials because of having elastic and attenuating properties as well as cost-effectiveness. Thus, the aim of this study was to prepare ground-breaking silicone rubber samples by adding WO₃-nanoparticles and testing the performance of their radiation shielding ability against Cs-137, Co-60, and Am-241 gamma energy. Increasing the concentration of WO₃ nanoparticles in silicone rubber (SR) led to decreasing the half-value layer (HVL) and mean free path (MFP) values determined for the samples tested. Furthermore, the values of MFP and HVL upsurged according to the enhancement of the photon energy. It is noteworthy that the prepared silicone rubber (SR) systems with 50 and 60 wt% concentrations of WO₃-nanoparticles displayed lower HVL than the Bi₂O₃-containing silicone rubber (SR) systems. In the same way, studied silicone rubber SR-W60 represented the lowest HVL comprising iron ore containing silicone rubber.

Investigation of the Gamma-ray Shielding Performance of CuO-CdO-Bi2O3 Bentonite Ceramics

The purpose of this research is to identify the radiation shielding capability of ceramics adding CuO, CdO, and Bi2O3 with diverse wt (%). The chemical compositions of the raw ceramics were documented through Energy Dispersive X-ray "EDX" techniques. For aesthetic appeal and solidification, CuO has been chosen to be added to ceramic. Moreover, in the interest of increasing the radiation shielding ability, the high atomic number and density of both CdO and Bi2O3 were suggested for the raw ceramics. To obtain the morphological features of the prepared ceramic samples, a Scanning Electron Microscope, or SEM, was utilized. To verify the experimental results, the MCA value obtained from the Phy-X software was compared to the experimental value collected from the HPGe detector. At energies 0.06 MeV, 0.662 MeV, 1.173 MeV, and 1.333 MeV the linear and mass attenuation coefficients of the prepared ceramics have been measured using a high purity germanium "HPGe" detector as well as three different point sources. Moreover, the relationship between ln(I) and the thickness of the ceramics has been presented here, and the comparison between the LAC of the prepared ceramics with other materials has also been displayed. Bentonite ceramic containing CuO (15 mol %)-CdO (15 mol %)-Bi2O3 (20 mol %) with density 3.6 showed the lowest HVL, MFP, and TVL at all studied energies, yet pure Bentonite ceramic containing only CuO (50 mol %), having density 3.4, presented the greatest values. Hence, it can be concluded that the addition of CdO and Bi2O3 enhances the radiation shielding ability.

Novel 3-D printed radiation shielding materials embedded with bulk and nanoparticles of bismuth

In the present study, a new type of radiation shielding material was developed by using a 3-D printing technique which enables to create a light radiation shielding materials of a great variety of shapes and dimensions. Micro and nano bismuth particles were incorporated as a filler between the inner layers of polylactic acid thermoplastic polymer (PLA Plastic) designed of the investigated 3-D printed prototypes to achieve the desired radiation attenuation. The effect of particle size on the attenuation parameters were studied over the energy range from 0.0595 to 1.41 MeV. The mass and thickness needed to reduce the intensity of the incoming radiation to half of its original value were determined experimentally for pure polymer (ABS Plastic), polymer with bulk Bi, and polymer with nano Bi. The results reveal that bismuth NPs with average particle size of about 17 ± 3 nm have a greater mass attenuation capability than normal bulk bismuth particles, meaning they are more efficient and a lighter shield can be produced. The enhanced shielding ability of nano bismuth particles was contributed to the excellent particle distribution, leading to an increase in the probability of photons interacting with the bismuth atoms. The bismuth NPs 3-D printed objects can be considered as a promising radiation shielding candidates and also could be utilized in manufacturing of radiation medical phantom.

The Influence of Bi2O3 Nanoparticle Content on the γ-ray Interaction Parameters of Silicon Rubber

In this study, synthetic silicone rubber (SR) and Bi₂O₃ micro- and nanoparticles were purchased. The percentages for both sizes of Bi₂O₃ were 10, 20 and 30 wt% as fillers. The morphological, mechanical and shielding properties were determined for all the prepared samples. The Linear Attenuation Coefficient (LAC) values of the silicon rubber (SR) without Bi₂O₃ and with 5, 10, 30 and 30% Bi₂O₃ (in micro and nano sizes) were experimentally measured using different radioactive point sources in the energy range varying from 0.06 to 1.333 MeV. Additionally, we theoretically calculated the LAC for SR with micro-Bi₂O₃ using XCOM software. A good agreement was noticed between the two methods. The NaI (Tl) scintillation detector and four radioactive point sources (Am-241, Ba-133, Cs-137 and Co-60) were used in the measurements. Other shielding parameters were calculated for the prepared samples, such as the Half Value Layer (HVL), Mean Free Path (MFP) and Radiation Protection Efficiency (RPE), all of which proved that adding nano-Bi₂O₃ ratios of SR produces higher shielding efficiency than its micro counterpart.

Novel Shielding Mortars for Radiation Source Transportation and Storage

New types of mortar, M1 (60% sand, 25% cement, 10% ball clay, and 15% WO3), M2 (50% sand, 25% cement, 10% ball clay, and 25% WO3), M3 (60% sand, 25% cement, 10% Barite, and 15% WO3), and M4 (50% sand, 25% cement, 10% Barite, and 25% WO3), were prepared and the impact of WO3 and barite on their radiation shielding performance and mechanical properties was evaluated. The radiation attenuation factors were evaluated using five radioactive point sources, and a sodium iodide (NaI) scintillation detector (3″ × 3″) was used to detect the attenuation of gamma ray photons emitted from radioactive sources. The density values of the mortar samples lie within the range of 2.358 and 2.602 g/cm3. The compressive strength and the tensile strength of the prepared mortars increased with the increasing percentage of WO3. The M4 mortar had the highest linear attenuation coefficient (LAC) value. The LAC results demonstrated that adding barite and a high percentage of WO3 into the mortars notably enhanced the radiation shielding performance of the prepared mortar. The relationship between the half value layer (HVL) and the energy is direct, and so was used to calculate the thickness of mortar needed to absorb or scatter half the number of low-energy photons falling on the samples. At 0.06 MeV, the HVL values of the samples were 0.412, 0.280, 0.242, and 0.184 cm for samples M1–M4, respectively. The highest HVL values, obtained at 1.408 MeV, were 5.516, 5.202, 5.358, and 5.041 cm. Thus, a thinner layer of the M4 sample provided comparable attenuation of photons and radiation protection to the thicker M1–M3 samples. The new material is promising as an effective shield of radiation-emitting sources during transportation and long-term storage.