Neutron-shielding behaviour investigations of some clay-materials

Geant4 Simulation of Photon- and Neutron-Shielding Capabilities of Biopolymer Blends of Poly(lactic acid) and Poly(hydroxybutyrate)

Simulation is used by scientists to imitate a real-life experimental setup in order to save time, costs and effort. Geant4, a toolkit based on the Monte Carlo method, has been widely used in investigating the radiation-shielding properties of different materials. In many recent studies, researchers have focused on polymers and their shielding capabilities. Poly(lactic acid) (PLA) is a widely used biopolymer in many applications due to its excellent mechanical properties. However, it has limitations related to its degree of crystallinity and molecular characteristics, which could be improved through blending with other biodegradable polymers such as poly(hydroxybutyrate) (PHB). Previous published studies have shown that the mechanical properties of such blends can be improved further. In this work, the effect of blending PHB with PLA on the photon- and neutron-shielding capabilities will be investigated using Geant4 over a wide energy range, as well as the effect of doping those blends with metal oxides. The results show that the shielding properties of the polymers are affected by blending with other polymers and by doping the polymer blends with different metal oxides, and they confirm that Geant4 is a very reliable tool that can simulate any material's shielding properties against photons and neutrons.

Geant4 Simulation of the Effect of Different Composites on Polyimide Photon and Neutron Shielding Properties

Polymers are widely used materials that have many medical and industrial applications. Some polymers have even been introduced as radiation-shielding materials; therefore, many studies are focusing on new polymers and their interactions with photons and neutrons. Research has recently focused on the theoretical estimation of the shielding effectiveness of Polyimide doped with different composites. It is well known that theoretical studies on the shielding properties of different materials through modeling and simulation have many benefits, as they help scientists to choose the right shielding material for a specific application, and they are also much more cost-effective and take much less time compared to experimental studies. In this study, Polyimide (C₃₅H₂₈N₂O₇) was investigated. It is a high-performance polymer, well known for its outstanding chemical and thermal stability, as well as for its high mechanical resistance. Because of its exceptional properties, it is used in high-end applications. The performance of Polyimide and Polyimide doped with different weight fractions of composites (5, 10, 15, 20 and 25 wt.%) as a shielding material against photons and neutrons were investigated using a Monte Carlo-based simulation toolkit Geant4 within a wide range of energies of both photons and neutrons from 10 to 2000 KeVs. Polyimide can be considered a good neutron shielding material, and its photon shielding abilities could be further enhanced when adding different high atomic number composites to it. The results showed that Au and Ag gave the best results in terms of the photon shielding properties, while ZnO and TiO₂ had the least negative effect on the neutron shielding properties. The results also indicate that Geant4 is a very reliable tool when it comes to evaluating the shielding properties against photons and neutrons of any material.

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.

Evaluation of Acrylonitrile Butadiene Styrene (ABS) polymer reinforced with Bi and TiO2 nanopowders for gamma and neutron shielding

3D printer technology has recently become easily reachable technology and are used to create simple or complex structures with high-quality. Its superior advantages could also be useful on the production of effective radiation shielding materials. On this purpose, the presented work studies the gamma and neutron shielding effectiveness of Acrylonitrile Butadiene Styrene (ABS) sample, a 3D printing material, reinforced with Bi and TiO2 nanopowders at various gamma and neutron energies. The gamma shielding properties were evaluated using experimental (High Purity Germanium detector system), theoretical (WinXCOM computer program) and simulation techniques (GEANT4 and FLUKA) in a wide gamma energy region ranging from 59.5 to 1332.5 keV. The investigation on neutron attenuation capabilities of the printed composites were performed with help of simulation and theoretical approaches for various sample thickness and neutron energies. The half value layer of ABS-Bi10 sample is found to be as 4.9565 cm, which is much smaller than some commercial polymers: polyvinylidenechloride, polyamide, polyacrylonitrile, polyphenylenesulfide, and unsaturated polyester. With the usage of 3D printing technology, significant enhancements in neutron and gamma shielding were reported.

Theoretical Investigation of Fast Neutron and Gamma Radiation Properties of Polycarbonate-Bismuth Oxide Composites Using Geant4

The gamma mass (µ_m) and linear (µ) attenuation coefficients of polycarbonate-bismuth oxide composites (PC-Bi₂O₃) with different bismuth oxide weight factors were investigated theoretically using EpiXS and a Monte Carlo simulation-based toolkit and Geant4 within an energy range between 0.1 and 2 MeV. The wide energy ranges of gamma rays and neutrons were chosen to cover as many applications as possible. The attenuation coefficients were then used to compute the half-value layers. The effective atomic numbers and effective electron densities of the studied samples obtained by EpiXS were compared as well. In order to further evaluate the shielding effectiveness of the studied samples, the thicknesses of all the investigated samples equivalent to 0.5 mm lead at a gamma energy of 511 keV were compared using a Geant4 code simulating a female numerical phantom with a gamma source placed facing the chest and a cylinder-shaped shield wrapped around the trunk area. The fast neutron removal cross sections of the investigated samples were studied to evaluate the effect of the weight factor of nanocomposites on the neutron shielding capabilities of the polymer as well.

Theoretical Investigation of Gamma- and Neutron-Shielding Properties of Polysulfone (PSU) Polymer Material Using Geant4

Polymers are widely used materials that have many medical and industrial applications. Some polymers have even been introduced as radiation-shielding materials; therefore, many studies are focusing on new polymers and their interactions with photons and neutrons. Research has focused on theoretical estimation of the shielding effectiveness of different materials. It is well known that theoretical studies on the shielding properties of different materials through modeling and simulation have many benefits, as they help scientists to choose the right shielding material for a specific application, and they are also much more cost-effective and take much less time compared to experimental studies. In this study, polysulfone (PSU) was investigated. PSU is a high-temperature, amber-colored, semi-transparent plastic material with good mechanical properties. It is resistant to degradation from hot water and steam and is often used in medical and food preparation applications, where repeated sterilization is required. The interactions of photons and neutrons with PSU were investigated using a Monte Carlo-based simulation toolkit, Geant4, within a wide range of energies of both photons and neutrons. The mass attenuation coefficients (µ_m), the half-value layers (HVL), the effective atomic numbers (Z_eff), and the effective electron densities (N_eff) of gammas were investigated. In addition, the effective removal cross-sections (Σ_R) and the mean free paths (λ) of neutrons were also studied. The results were then compared to other commonly used polymer materials.

Radiation attenuation properties of B2O3-ZnO-Al2O3-Bi2O3-Sm2O3 glasses

The goal of this study is to examine theoretically radiation absorption properties of zinc alumino bismuth borate (BZnAlBiSm) glasses with chemical formula 60B2O3-9ZnO-(30-x)Al2O3-xBi2O3-1Sm2O3 where x = 5, 10, 15 and 20 mol%. The linear and mass attenuation coefficents of BZnAlBiSm glasses turn out as this trend BZnAlBiSm-1<BZnAlBiSm-2<BZnAlBiSm-3<BZnAlBiSm-4. The BZnAlBiSm-4 with the smallest half value layers, tenth value layers and mean free paths in the examined energy ranges has the superior radiation shielding characteristics among the BZnAlBiSm glasses. The BZnAlBiSm-4 glass has the highest radiation protection efficiency among the BZnAlBiSm glasses. The transmission factors increase as photon energy range enhances from 0.015 to 15 MeV and thickness declines from 2.5 to 0.5 cm. The energy buildup factors and energy absorption buildup factors of BZnAlBiSm glasses reduce from 15 to 1 mfp. Variation of the effective atomic number and effective electron density as a function of photon energy for BZnAlBiSm glasses are similar. The projected ranges of electron, proton, alpha and carbon for the BZnAlBiSm glasses increase as photon energy enlarges. The fast neutron removal cross sections of the BZnAlBiSm glasses vary in order of BZnAlBiSm-4<BZnAlBiSm-3<BZnAlBiSm-2<BZnAlBiSm-1. Thus, it can be concluded that BZnAlBiSm-1 has the highest neutron absorption ability among the BZnAlBiSm glasses.

Evaluation of gamma ray and neutron attenuation capability of thermoplastic polymers

The fast neutron and gamma ray attenuation capability of the most common thermoplastic polymers used in nuclear applications has been evaluated theoretically. Monte Carlo simulation has been used to compute the gamma-ray energy absorption buildup factor in the energy range 0.015-15 MeV at penetration depths up to 40 MFP. The results of MCNPX calculations have been validated against the results derived from the Geometric Progression fitting method. To evaluate neutron attenuation performance of the polymers, the fast neutron removal cross-section has been determined using theoretical database. Despite the superior ability of polysulfone and poly (ether sulfone) in gamma ray attenuation, high-density polyethylene has been found to have the best fast neutron removal ability among all. The detailed insights into the fast neutron and gamma ray shielding properties of selected polymers in the present work might have great potential applications in nuclear systems.

Neutron shielding calculations for neutron imaging facility at the Maâmora Triga reactor

The build of neutron imaging facility is planned in the tangential beam around the TRIGA 2 MW, located in the Mâamora Nuclear Research Centre of Morocco. The design of this equipment and the plans for all operations should be evaluated in advance for the adequacy of radiation protection. Cement and concrete has been widely used as shielding material in a nuclear reactor in order to minimize exposure to individuals. In this paper GEANT4 and FLUKA simulation toolkit were used to study neutron attenuation, and optimizing the layers of shielding material to minimize thickness. Materials being studied include different types of concrete such as Hematite and Hormirad mixed borax with different boron and iron compositions. Initial studies indicate that optimized shielding material is Hematite. A total thickness of 700 mm produces the required attenuation factor. Further studies may allow optimizing the shielding enclosures. Because of the low floor load (5000 kg/m²), one solution that could be adopted is the substitution one bloc shielding by two blocks (with a half thickness) with air gap between them. The model allows studying the performance of the shielding materials in this particular space arrangement. The main goal is to maintain the total dose outside the shield boundary less than 5.0e-03 mSv/h during operation.