Search Results (189)

This study investigates the dyke swarms of the Um Dwiela area in the southern Egyptian Shield through a combined approach of remote sensing, field investigations and laboratory analyses, including mineralization and radioactive prospecting. Radioelements laboratory measurements and optical remote sensing datasets are combined to detect the bostonite rocks and their radioactive mineralization. The processing of Landsat-8, Sentinel-2 and ASTER data effectively delineated the country rocks, bostonite dykes and structural elements. Field observations indicate that the dykes trend NE-SW, extending approximately 12 km with widths ranging from 1 to 13 m. These dykes have experienced multiple alteration phases, pointing to the influence of hydrothermal fluids. Uranium mineralization is structurally controlled, occurring within fractures at the contact between bostonite and metasedimentary rocks. Average measurements obtained using a NaI(Tl) analyzer reveal elevated and variable radionuclide concentrations [²³²Th (442.25 Bq/kg), ²³⁸U (608.43 Bq/kg), and ⁴⁰K (1141.41 Bq/kg)], all exceeding internationally permissible safety limits. Multiple radiological hazard indices further indicate a substantial radiation risk, with all values classified as high according to global standards. Consequently, the associated gamma radiation exposure poses an elevated radiological hazard concern. Full article

In this study, the radiation-shielding, mechanical, microstructural, and thermal properties of gypsum-based composites modified with thermally treated colemanite were investigated. Composite samples containing 1, 2.5, 5, and 10 wt.% colemanite were prepared, and the additive was pre-treated at 650 °C to improve its stability and compatibility with the matrix. Gamma-ray attenuation was evaluated at different photon energies, and neutron attenuation was determined using a ²⁴¹Am–Be source. The results showed that colemanite addition improves gamma-ray attenuation, particularly at low and medium energies, with the best performance observed at 2.5–5 wt.%. Neutron attenuation increased with an increasing colemanite content due to the presence of boron. Compressive strength exhibited a non-linear trend, reaching its maximum at 2.5 wt.% and decreasing at higher contents due to microstructural changes. Thermal conductivity also showed non-linear behavior, with the lowest value obtained at 5 wt.% colemanite. SEM and FTIR analyses confirmed the incorporation of colemanite and its influence on the microstructure. Overall, the results indicate that colemanite-modified gypsum composites provide a balanced combination of radiation-shielding, thermal insulation, and mechanical performance. Full article

This study developed high-performance, biodegradable nanocomposites from polyvinyl alcohol (PVA) reinforced with nanocellulose derived from the invasive Nile rose plant (NR). Cellulose nanofibrils (CNFs) were successfully extracted using maleic anhydride treatment, yielding nanofibers with an average diameter of 20.81 nm and a high negative surface charge of −40.7 mV, indicating effective functionalization. The synergistic effect of incorporating 7.5% CNF and applying 50 kGy gamma irradiation dramatically enhanced the composite properties, resulting in a 64.01% improvement in tensile strength compared to neat PVA. The crosslinked network significantly increased hydrophobicity, with the water contact angle rising from 60.95° to 106.40°, and reduced moisture absorption. Optical characterization demonstrated excellent UV-shielding capabilities, maintaining a visible light transmittance of 66.6% at 800 nm, while thermal analysis confirmed enhanced stability against high-temperature degradation. These findings suggest that the developed nanocomposites are promising candidates for advanced protective packaging applications where UV shielding and moisture resistance are critical. Full article

To address underground shotcrete support scenarios with potential radiation-protection requirements, a bismuth oxide/clay functional filler was incorporated into a baseline shotcrete formulation. Functional filler dosage, calcium formate dosage, and PCE dosage were selected as variables, and Box–Behnken response surface methodology was used to establish quadratic regression models for 28 d compressive strength, fluidity, and bond strength. Representative optimized mixtures were further evaluated by MCNP5 simulation, gamma-ray air-kerma attenuation tests, and SEM. The models showed good fitting and predictive performance within the investigated design space. Functional filler dosage mainly controlled compressive strength and bond strength, whereas PCE dosage dominated fluidity. Under the constraints of compressive strength ≥ 25 MPa, fluidity of 160–170 mm, and bond strength ≥ 0.8 MPa, three representative mixtures were selected for shielding-, strength-, and interface-priority strategies. Simulated and measured results showed consistent shielding-performance rankings, and the optimized mixtures exhibited higher gamma-ray attenuation than the blank mixture. BBD26 achieved the highest shielding performance, with measured shielding rates of 65.51% and 51.54% at 661.7 keV and 1.25 MeV, respectively. Thickness-gradient tests indicated exponential attenuation, while SEM revealed differences in Bi-bearing particle distribution and matrix continuity. Full article

Functionally graded AA2024/B₄C metal matrix composites were fabricated via mechanical alloying and hot pressing to investigate structure–property–radiation shielding relationships. Single-layer, two-layer, and three-layer architectures with varying B₄C contents were systematically produced. Microstructural homogeneity and phase constitution were examined using SEM/EDS and XRD, while thermal stability was evaluated by thermogravimetric analysis. Density and porosity measurements were conducted to assess the influence of reinforcement distribution and functional grading on densification behavior. Gamma radiation shielding performance was experimentally evaluated using a ¹⁵²Eu source and an HPGe detector over a wide photon energy range. Key shielding parameters, including linear and mass attenuation coefficients, half-value layer, tenth-value layer, mean free path, and radiation protection efficiency, were determined. The results reveal that functional grading significantly enhances radiation attenuation compared to monolithic composites. The three-layer AA2024/B₄C composite exhibited the highest attenuation coefficients and the lowest HVL, TVL, and MFP values at all investigated energies, achieving nearly 100% improvement in shielding efficiency relative to unreinforced AA2024. These findings demonstrate that controlled B₄C distribution and layered composite architecture provide a synergistic improvement in thermal stability, physical integrity, and radiation shielding performance, positioning functionally graded AA2024/B₄C composites as efficient lightweight materials for advanced radiation shielding applications. These results indicate that the developed functionally graded AA2024/B₄C composites are promising candidates for advanced radiation shielding applications in nuclear facilities, aerospace structures, and medical radiation protection systems, where lightweight and high-performance materials are critically required. Full article

This study investigates the development of a high-density W-Ni-Fe alloy using liquid-phase sintering and examines its microstructure and mechanical properties. Critical parameters, including sintering time and heating rate, were optimized to achieve enhanced density, microhardness, tensile strength, and γ-ray shielding properties. The results show that optimal sintering conditions (45 min at a heating rate of 30 K/min and a sintering temperature of 1753 K) lead to a uniform dispersion of tungsten particles, with a high-volume fraction of tungsten in the matrix and enhanced bonding within the γ(Ni-Fe) matrix. The alloy achieved a density of 16.99 g/cm³ and exhibited superior mechanical performance, with a tensile strength of 846.66 MPa and an elongation of 10.5%, as well as excellent γ-ray attenuation capabilities. These results demonstrate its suitability for nuclear applications. Full article

Superheated liquid detectors (SLDs) exhibit strong sensitivity to fast neutrons and intrinsic insensitivity to gamma radiation, making them promising candidates for detecting shielded nuclear materials in security and non-proliferation applications. This work evaluates the feasibility of octafluoropropane-based superheated droplet detectors (SDDs) for identifying neutron-emitting materials concealed behind common attenuators. A combined acoustic and optical readout system was implemented, including a validated pulse-shape analysis method and a machine-learning-based bubble detection algorithm using YOLOv5. The optical system achieved a detection precision of approximately 80% within the defined region of interest. While the acoustic system remains the primary and more mature detection channel, the optical approach demonstrates feasibility but is not yet operationally ready for field deployment. Experiments with an AmBe neutron source and various shielding materials demonstrate that SDDs reliably detect fast neutrons under realistic inspection conditions while remaining insensitive to gamma radiation. These results support the feasibility of SLD-based systems as low-cost, passive tools for detecting shielded nuclear materials in field environments. Full article

Shutdown dose rate (SDDR) assessments have been performed for the DEMO tokamak model, including the latest design and environmental configurations. The main objective of this study was to evaluate the shutdown radiation fields and establish dose rate limits to ensure safe personnel access to the Vacuum Vessel (VV) and nearby components. The simulations were based on the DEMO baseline model, further refined with the minor updates of the lower port, equatorial port limiter, and upper port assemblies. The computational approach employed the Monte Carlo particle transport code MCNP for neutron and photon transport calculations, coupled with the activation and decay code FISPACT-II to determine time-dependent decay gamma source terms. The mesh-coupled Rigorous Two-Step (R2Smesh) methodology developed in KIT was applied to achieve spatially resolved decay of photon source distributions and to compute corresponding SDDR 3D maps within the DEMO reactor configuration. The results provide a detailed characterization of the residual radiation environment inside the VV, offering insight into the accumulated activity, shielding performance of different materials, and potential access scenarios for maintenance operations in next-generation fusion devices. Full article

This study evaluates lead-free high-density polyethylene (HDPE) composites reinforced with high-Z oxides (Bi₂O₃, WO₃, Gd₂O₃, TeO₂, and a Bi₂O₃/WO₃ hybrid) as lightweight materials for gamma-ray and fast-neutron shielding. A hybrid computational framework combining Phy-X/PSD with Geant4 Monte Carlo simulations was used to obtain key shielding parameters, including the linear and mass attenuation coefficients (μ, μ/ρ), half-value layer (HVL), mean free path (MFP), effective atomic number (Z_eff), effective electron density (N_eff), exposure and energy-absorption buildup factors (EBF, EABF), and fast-neutron removal cross section (Σ_R). The incorporation of heavy oxides produced a pronounced improvement in gamma-ray attenuation, particularly at low energies, where the linear attenuation coefficient increased from below 1 cm⁻¹ for neat HDPE to values exceeding 130–150 cm⁻¹ for Bi- and W-rich composites. In the intermediate Compton-scattering region (≈0.3–1 MeV), all oxide-reinforced systems maintained a clear attenuation advantage, with μ values around 0.12–0.13 cm⁻¹ compared with ≈0.07 cm⁻¹ for pure HDPE. At higher photon energies, the dense composites continued to outperform the polymer matrix, yielding μ values of approximately 0.07–0.09 cm⁻¹ versus ≈0.02 cm⁻¹ for HDPE due to enhanced pair-production interactions. The Bi₂O₃/WO₃ hybrid composite exhibited attenuation behavior comparable, and in some regions slightly exceeding, that of the single-oxide systems, indicating that mixed fillers can effectively balance density and shielding efficiency. Oxide addition significantly reduced exposure and energy-absorption buildup factors below 1 MeV, with a moderate increase at higher energies associated with secondary radiation processes. Fast-neutron removal cross sections were also modestly enhanced, with Gd₂O₃-containing composites showing the highest values due to the combined effects of hydrogen moderation and neutron capture. The close agreement between Phy-X/PSD and Geant4 results confirms the reliability of the dual-method approach. Overall, HDPE composites containing about 60 wt.% oxide filler offer a practical compromise between shielding performance, manufacturability, and environmental safety, making them promising candidates for medical, nuclear, and aerospace radiation-protection applications. Full article

In recent years, polymer-based hybrid nanocomposites have emerged as promising alternatives to traditional heavy metal shields due to their low density, flexibility, and environmental safety. In this study, the synthesis of PS-PEG copolymers and the gamma radiation-shielding properties of PS-PEG/As₂O₃, PS-PEG/BN, and PS-PEG/As₂O₃/BN nanocomposites with different compositions are investigated. The goal is to find the optimal nanocomposite composition for gamma radiation shielding and dosimetry. Therefore, the mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), half-value layer (HVL), tenth-value layer (TVL), effective atomic number, mean free path (MFP), radiation shielding efficiency (RPE), electron density, and specific gamma-ray constant were presented. Gamma rays emitted by the Eu source were detected by a high-purity germanium (HPGe) detector device. GammaVision was used to analyze the given data. Photon energy was in the vicinity of 121.8–1408.0 keV. The MAC values in XCOM simulation tools were used to compute. Gamma-shielding efficiency was increased by an increased number of NPs at a smaller photon energy. At 121.8 keV, the HVL of a composite with 70 wt% As₂O₃ NPs is 2.00 cm, which is comparable to the HVL of lead (0.56 cm) at the same energy level. Due to the increasing need for lightweight, flexible, and lead-free shielding materials, PS-b-PEG copolymer-based nanocomposites reinforced with arsenic oxide and BN NPs will be materials of significant interest for next-generation radiation protection applications. Full article

Environmentally friendly materials with superior structural, physical, optical, and shielding capabilities are of great technological importance and are continually being investigated. In this work, novel multicomponent borate glasses with the composition xTiO₂-10BaO-5Al₂O₃-5WO₃-20Bi₂O₃-(60-x) B₂O₃, where 0 ≤ x ≤ 15 mol%, were produced via the melt-quenching technique. The increase in TiO₂ content results in a decrease in molar volume and a corresponding increase in density, indicating the formation of a compact, rigid, and mechanically hard glass network. Elastic constant measurements further confirmed this behavior. FTIR analysis confirms the transformation of BO₃ to BO₄ units, signifying improved network polymerization and structural stability. The prepared glasses exhibit an optical absorption edge in the visible region, demonstrating their strong ultraviolet light blocking capability. Incorporation of TiO₂ leads to an increase in refractive index, optical basicity, and polarizability, and a decrease in the optical band gap and metallization number; all of these suggest enhanced electron density and polarizability of the glass matrix. Radiation shielding properties were evaluated using Phy-X/PSD software. The outcomes illustrate that the Mass Attenuation Coefficient (MAC), Effective Atomic Number (Z_eff), Linear Attenuation Coefficient (LAC) increase, while Mean Free Path (MFP) and Half Value Layer (HVL) decrease with increasing TiO₂ at the expense of B₂O₃, confirming superior gamma-ray attenuation capability. Additionally, both TiO₂-doped and undoped samples show higher fast neutron removal cross sections (FNRCS) compared to several commercial glasses and concrete materials. Overall, the incorporation of TiO₂ significantly enhances the optical performance and radiation-shielding efficiency of the environmentally friendly glass system, making these potential candidates for advanced photonic devices and radiation-shielding applications. Full article

It is well known that the space radiation environment, which has contributions from the trapped particles within the Van Allen belts, solar energetic particles (SEPs) and galactic cosmic rays (GCRs), directly influences space systems. These systems rely on complex and fragile electronic devices, whose performance can be degraded because of the action of the radiation and its related phenomena: single-event effects (SEEs), displacement damages (DDs) and total ionizing dose (TID). This could cause failures to arise through various mechanisms, ranging from parametric drift failures, such as leakage current and threshold voltage, among others, to destructive effects, like single-event burnout (SEB) or single-event latch-up (SEL). These failures in electronics affect the system’s reliability and its performance, which could compromise the mission’s success. Considering this, the main objective of the SRPROTEC project is to develop and validate new composite materials with better shielding performance against space radiation to increase the radiation tolerance of microelectronic devices encapsulated with these materials. For this purpose, three composites will be synthesized using a liquid epoxy resin filled with silica as a matrix mixed in different proportions, with a high-Z filler. The presence of low-Z elements from the high hydrogen content in the polymer and the presence of high-Z fillers are expected to produce a material with good radiation shielding properties. The developed materials will be exhaustively characterized, subjecting the three composites and control samples to rheological outgassing; gamma radiation shielding; and thermal, electrical, thermomechanical and moisture absorption, among other tests. Finally, the composite with the best performance will be selected and subjected to degradation tests (thermal cycling in vacuum, thermal cycling, thermal shock and relative humidity tests) to determine its suitability for space packaging applications. Full article

The rapid development of deep-space exploration and crewed missions makes efficient, lightweight, and low–secondary-radiation γ-ray protection in complex cosmic fields a critical materials challenge. Current studies still struggle to simultaneously balance attenuation efficiency, areal density and thickness, flexibility, and shielding against secondary γ rays. Compared with existing reviews that mainly focus on single matrices (especially polymers) or medical lead-based protection, this work targets γ-ray shielding under deep-space and mixed radiation environments, emphasizing multiscale structural designs (multilayer/gradient architectures, micro/nanofiller synergy, and fiber networks) for suppressing secondary γ-rays and outlining composition–structure–morphology–coupled strategies for flexible, wearable, lead-free shields. Recycling and sustainability remain key bottlenecks for practical deployment. Accordingly, this review also summarizes representative Monte Carlo simulation tools and their integration with experiments, and proposes directions for element selection, structural design, and green manufacturing to build design rules and a scale-up roadmap for next-generation lead-free γ-shielding wearables. Full article

Lightweight and lead-free radiation shields are increasingly developed to overcome the toxicity and handling challenges associated with conventional heavy-metal-based materials. In this study, the $\gamma$-ray attenuation behavior of polymer–zeolite composites was examined by reinforcing high-density polyethylene (HDPE) and polylactic acid (PLA) with natural clinoptilolite zeolite at concentrations of 10–40 wt%. Photon-interaction parameters, including the linear attenuation coefficient ($\mu$), half-value layer (HVL), mean free path ($\lambda$), and effective atomic number ($Z_{\mathrm{eff}}$), were evaluated over 15 keV–15 MeV using the Phy-X/PSD platform. Zeolite incorporation consistently enhanced photon attenuation, particularly at low energies dominated by the photoelectric effect. At 15 keV, the HVL decreased from 0.60 cm to 0.08 cm for HDPE and from 0.043 cm to 0.033 cm for PLA as the zeolite loading increased to 40 wt%. Correspondingly, $Z_{\mathrm{eff}}$ increased from 2.7 to 4.3 for HDPE and from 6.5 to 11.6 for PLA, while $\mu$ reached approximately 41 cm⁻¹ and 56 cm⁻¹ at 15 keV for the respective 40 wt% composites. Beyond about 1 MeV, differences between compositions became minimal as Compton scattering dominated. PLA–zeolite composites exhibited higher $\mu$ and lower HVL than HDPE–zeolite, whereas HDPE maintained an advantage in mixed-field environments owing to its hydrogen-rich matrix. The results confirm that zeolite-reinforced polymers are safe, low-cost, and lightweight materials suitable for radiation shielding in medical, nuclear, and aerospace applications. Full article

The increasing demand for sustainable and multifunctional materials in radiation shielding and optical applications has driven research toward utilizing natural and waste-derived reinforcements in polymer matrices. However, achieving effective attenuation performance across different radiation types using eco-friendly fillers remains a significant challenge. In this study, polyvinyl chloride (PVC)/Polystyrene (PSt) blend composites (1:1 weight ratio) were reinforced with powdered snail shell (SSP) as a biogenic additive, aiming to enhance their shielding and optical performance. Composites containing 5%, 10%, 20%, and 30% SSP (w/v) were fabricated and characterized. Key parameters including linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), mean free path (MFP), half-value layer (HVL), and effective atomic number (Zeff) were measured using a variable-energy X-ray source (13.37–59.54 keV) and ULEGe detector. Fast neutron shielding performance and theoretical values for build-up factor (EBF) and macroscopic neutron cross-sections were also calculated. The results showed a marked improvement in X-ray attenuation with increasing SSP content (SSP30 > SSP20 > SSP10 > SSP5), while neutron shielding declined due to the high oxygen content of SSP. Among the tested samples, the SSP30 composite exhibited the highest X-ray attenuation efficiency, whereas the SSP5 composition showed the greatest enhancement in optical reflectance and neutron absorption, indicating optimal performance in these respective tests. Additionally, 5% SSP incorporation improved optical reflectance by 12%, indicating enhanced photon backscattering at the material surface. This behavior contributes to improved gamma shielding efficiency by reducing photon penetration and enhancing surface-level attenuation. These findings highlight the potential of snail shell-based fillers as low-cost, sustainable reinforcements in multifunctional polymer composites. Full article