Attenuation properties of poly methyl methacrylate reinforced with micro/nano ZrO2 as gamma-ray shields.

This research aimed to examine the radiation shielding properties of unique polymer composites for medical and non-medical applications. For this purpose, polymer composites, based on poly methyl methacrylate (PMMA) as a matrix, were prepared and reinforced with micro- and nanoparticles of ZrO2 fillers at a loading of 15%, 30%, and 45% by weight. Using the high purity germanium (HPGe) detector, the suggested polymer composites' shielding characteristics were assessed for various radioactive sources. The experimental values of the mass attenuation coefficients (MAC) of the produced composites agreed closely with those obtained theoretically from the XCOM database. Different shielding parameters were estimated at a broad range of photon energies, including the linear attenuation coefficient (µ), tenth value layer (TVL), half value layer (HVL), mean free path (MFP), effective electron density (Neff), effective atomic number (Zeff), and equivalent atomic number (Zeq), as well as exposure buildup factor (EBF) and energy absorption buildup factor (EABF) to provide more shielding information about the penetration of γ-rays into the chosen composites. The results showed that increasing the content of micro and nano ZrO2 particles in the PMMA matrix increases µ values and decreases HVL, TVL, and MFP values. P-45nZ sample with 45 wt% of ZrO2 nanoparticles had the highest µ values, which varied between 2.6546 and 0.0991 cm-1 as γ-ray photon energy increased from 0.0595 to 1.408 MeV, respectively. Furthermore, the highest relative increase rate in µ values between nano and micro composites was 17.84%, achieved for the P-45nZ sample at 59.53 keV. These findings demonstrated that ZrO2 nanoparticles shield radiation more effectively than micro ZrO2 even at the same photon energy and filler wt%. Thus, the proposed nano ZrO2/PMMA composites can be used as effective shielding materials to lessen the transmitted radiation dose in radiation facilities.

Novel slag/natural rubber composite as flexible material for protecting workers against radiation hazards.

This work is an attempt to employ the electric arc furnace (EAF) slag as a by-product material to develop an alternative and environmentally friendly material for gamma-radiation protection applications such as in medical and industrial areas. For this purpose, different concentrations of micro-sized EAF slag (0, 20, 40, 60, 80, 100, 500, and 800 phr) were incorporated as fillers in the natural rubber (NR) matrix to produce the shielding composites. In addition, nano-sized EAF slag particles were prepared by using a high-energy ball milling technique to investigate the effect of particle size on the gamma-radiation shielding properties. The synthesized micro and nano EAF/NR composites were tested as protective materials against gamma-radiation by employing NaI(Tl) scintillation detector and standard radioactive point sources (152Eu, 137Cs, 133Ba, and 60Co). Different shielding parameters such as linear and mass attenuation coefficient, half value layer (HVL), tenth value layer, mean free path, effective atomic number (Zeff), and effective electron density (Neff) were determined to assess the radiation shielding capability of the EAF/NR composites. Furthermore, equivalent atomic number (Zeq) and the exposure buildup factor values for photon energy in the range from 0.015 to 15 MeV were also computed by Geometric Progression method. The experimental results of micro EAF/NR composites showed that at 121.78 keV, EAF0 composite (without EAF slag content) had the lowest µ value of 0.1695 cm-1, while the EAF800 composite (which was loaded with 800 phr of micro EAF slag) had the highest µ value of 0.2939 cm-1 at the same energy, which in turn decreases the HVL from 4.09 to 2.36 cm, respectively. Therefore, increasing the filler weight fractions of EAF slag in the NR matrix, increases the shielding properties of the composites. Moreover, the NR composite reinforced with 800 phr of nano EAF slag has better gamma-radiation shielding efficiency compared to that filled with 800 phr of micro EAF slag. The success of this work was to prepare a flexible, lightweight, low-cost, and lead-free material with better shielding capability.

Radiation shielding performance of metal oxides/EPDM rubber composites using Geant4 simulation and computational study.

This paper aimed to evaluate the shielding performance of ethylene propylene diene monomer (EPDM) rubber composites filled with 200 phr of different metal oxides (either Al2O3, CuO, CdO, Gd2O3, or Bi2O3) as protective materials against gamma and neutron radiations. For this purpose, different shielding parameters, including the linear attenuation coefficient (µ), mass attenuation coefficient (µ/ρ), mean free path (MFP), half value layer (HVL), and tenth value layer (TVL), were calculated in the energy range between 0.015 and 15 MeV by using the Geant4 Monte Carlo simulation toolkit. The simulated µ/ρ values were validated by the XCOM software to examine the precision of the simulated results. The maximum relative deviation between the Geant4 simulation and XCOM was not greater than 1.41%, confirming the accuracy of the simulated results. Based on µ/ρ values, other significant shielding parameters such as effective atomic number (Zeff), effective electron density (Neff), equivalent atomic number (Zeq), and exposure buildup factor (EBF) were also computed to explore the potential usage of the proposed metal oxide/EPDM rubber composites as radiation protective materials. The study demonstrates that the gamma-radiation shielding performance of the proposed metal oxide/EPDM rubber composites are increasing in the order of EPDM < Al2O3/EPDM < CuO/EPDM < CdO/EPDM < Gd2O3/EPDM < Bi2O3/EPDM. Furthermore, three sudden increases in the shielding capability in some composites occur at 0.0267 MeV for CdO/EPDM, 0.0502 MeV for Gd2O3/EPDM, and 0.0905 MeV for Bi2O3/EPDM composites. This increase in the shielding performance is due to the K absorption edges of Cd, Gd, and Bi, respectively. Regarding the neutron shielding performance, the macroscopic effective removal cross-section for fast neutrons (Æ©R) was evaluated for the investigated composites using MRCsC software. The highest Æ©R is obtained for Al2O3/EPDM, while the lowest Æ©R is obtained for EPDM rubber with no metal oxide content. According to the obtained results, the investigated metal oxide/EPDM rubber composites can be employed as comfortable clothing and gloves designed for workers in radiation facilities.

A New Environmentally Friendly Mortar from Cement, Waste Marble and Nano Iron Slag as Radiation Shielding.

Improving mortar shielding properties to preserve environmental and human safety in radiation facilities is essential. Conventional cement mortars, composed of cement, water, and lime aggregate, are crucial for radiation shielding. Using recycled aggregates to produce new mortar and concrete compositions has attracted the attention of several researchers. In the current study, waste marble and iron slag as aggregates are used to create novel cement mortar compositions to study the aggregate's impact on the radiation attenuation capability of the mortar. Three mortar groups, including a control mortar (CM-Ctrl), were prepared based on cement and waste marble. The other two groups (CM-MIS, CM-NIS), contained 25% iron slag at different particle sizes as a replacement for a waste marble. The study aims to compare iron slag in their micro and nano sizes to discuss the effect of particle size on the mortar radiation capability. For this purpose, the NaI scintillation detector and radioactive point sources (241Am, 133Ba, 137Cs, 60Co, and 152Eu) were utilized to measure several shielding parameters, such as the linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP), for the produced mortars at different photon energies. Furthermore, the transmission electron microscope (TEM) is used to measure the particle size of the aggregates. In addition, a scanning electron microscope (SEM) is utilized to acquire the cross-section morphologies of the prepared mortars. According to our findings, mortars prepared with nano-iron slag and waste marble offered superior shielding capabilities than mortars containing natural sand or fine crushed stone. The nano iron slag mortar can be utilized in place of typical sand mortar for applications as rendering or plastering materials for building medical diagnostic and CT scanner rooms, due to its improved shielding abilities.

Enhancing the Gamma-Radiation-Shielding Properties of Gypsum-Lime-Waste Marble Mortars by Incorporating Micro- and Nano-PbO Particles.

In the current study, the gamma-radiation-shielding characteristics of novel gypsum-lime-waste marble-based mortars reinforced with micro-PbO and nano-PbO powders were investigated. In total, seven mortar groups, including a control mortar (named GLM), were prepared. The other groups contained10, 20, and 30 wt.% of both micro-PbO and nano-PbO as a waste marble replacement. This study aimed to explore the effect of particle size and concentrations of PbO powders on the γ-ray-shielding capability of GLM mortars. For this purpose, an HPGe detector and five standard radioactive point sources (241Am, 133Ba, 137Cs, 60Co, and 152Eu) were employed to measure different shielding parameters, including the linear attenuation coefficient (µ), mass attenuation coefficient (µm), mean free path (MFP), half-value layer (HVL), and tenth-value layer (TVL), for the prepared samples in the energy range between 59.53 keV to 1408.01 keV. On the basis of µm values, other significant shielding parameters such as effective atomic number (Zeff), effective electron density (Neff), equivalent atomic number (Zeq), and exposure buildup factor (EBF) were also computed to explore the potential usage of the proposed mortars as radiation protective materials. The results reported that the smallest HVL, TVL, and MPF, as well as the largest attenuation values, were obtained for mortars reinforced by nano-PbO compared to those containing micro-PbO. It can be concluded from the results that the mortar samples containing nano-PbO had a remarkably improved gamma-radiation-shielding ability. Thus, these mortars can be used for radiation shielding on walls in nuclear facilities to reduce the transmitted radiation dose.

Gamma Attenuation Features of White Cement Mortars Reinforced by Micro/Nano Bi2O3 Particles.

This study aims to explore the radiation protection properties of white mortars based on white cement as a binder and Bi2O3 micro and nanoparticles in proportions of 15 and 30% by weight as replacement sand. The average particle size of micro- and nano-Bi2O3 was measured using a transmission electron microscope (TEM). The cross-sectional morphology and distribution of Bi2O3 within the samples can be obtained by scanning electron microscopy (SEM), showing that nanoscale Bi2O3 particles have a more homogeneous distribution within the samples than microscale Bi2O3 particles. The shielding parameters of the proposed mortars were measured using the HPGe detector at various γ-ray energies emitted by standard radioactive point sources 241Am, 133Ba, 60Co, 137Cs, and 152Eu. The experimental values of the prepared mortars' mass attenuation coefficients (MAC) match well with those determined theoretically from the XCOM database. Other shielding parameters, including half value layer (HVL), tenth value layer (TVL), mean free path (MFP), effective electron density (Neff), effective atomic number (Zeff), equivalent atomic number (Zeq), and exposure buildup factor (EBF), were also determined at different photon energies to provide more shielding information about the penetration of gamma radiation into the selected mortars. The obtained results indicated that the sample containing 30% by weight of nano Bi2O3 has the largest attenuation coefficient value. Furthermore, the results show that the sample with a high concentration of Bi2O3 has the highest equivalent atomic numbers and the lowest HVL, TVL, MFP, and EBF values. Finally, it can be concluded that Bi2O3 nanoparticles have higher efficiency and protection compared to microparticles, especially at lower gamma-ray energies.

Gamma-Ray Attenuation and Exposure Buildup Factor of Novel Polymers in Shielding Using Geant4 Simulation.

Polymers are often used in medical applications, therefore, some novel polymers and their interactions with photons have been studied. The gamma-ray shielding parameters for Polymethylpentene (PMP), Polybutylene terephthalate (PBT), Polyoxymethylene (POM), Polyvinylidenefluoride (PVDF), and Polychlorotrifluoroethylene (PCTFE) polymers were determined using the Geant4 simulation and discussed in the current work. The mass attenuation coefficients (µ/ρ) were simulated at low and high energies between 0.059 and 1.408 MeV using different radionuclides. The accuracy of the Geant4 simulated results were checked with the XCOM software. The two different methods had good agreement with each other. Exposure buildup factor (EBF) was calculated and discussed in terms of polymers under study and photon energy. Effective atomic number (Zeff) and electron density (Neff) were calculated and analyzed at different energies. Additionally, the half-value layer (HVL) of the polymers was evaluated, and the results of this parameter showed that PCTFE had the highest probability of interaction with gamma photons compared to those of the other tested polymers.

Gamma Attenuation Coefficients of Nano Cadmium Oxide/High density Polyethylene Composites.

In the present work, high density polyethylene (HDPE) matrix mixed with micro-sized and nano-sized Cadmium oxide (CdO) particles of different concentrations were prepared by compression molding technique. The aim of the study is to investigate the effect of particle size and weight percentage of CdO particles on the gamma radiation shielding ability of CdO/HDPE composites. The mass attenuation coefficients of pure HDPE, micro-CdO/HDPE and nano-CdO/HDPE composites were evaluated at photon energies ranging from 59.53 keV to 1408.01 keV using standard radioactive point sources [241Am, 133Ba, 137Cs, 60Co and 152Eu]. Adding micro and nano CdO particles to the HDPE matrix clearly increases the mass attenuation coefficients of the composites and the improvement is more significant at low γ-ray energies. The effect of particle size of CdO filler has an important role on the shielding ability of the composite. The experimental results reveal that, the composites filled with nano-CdO have better γ-radiation shielding ability compared to that filled with micro-CdO at the same weight fraction. A relative increase rate of about 16% is obtained with nano-CdO content of 40 wt% at 59.53 keV, which attributed to the higher probability of interaction between γ-rays and nanoparticles. From this study, it can be concluded that nano-CdO has a good performance shielding characteristic than micro-CdO in HDPE based radiation shielding material.