Radiological consequence assessment is essential for evaluating emergency preparedness at nuclear power sites, especially where plant-specific licensing data are not yet available. In Morocco, Sidi Boulbra was historically retained as a candidate nuclear power plant site; however, site-specific screening assessments of hypothetical large advanced pressurized water reactor (PWR) accident consequences using long-term local meteorology remain limited. Therefore, this study evaluates two hypothetical accident scenarios using a literature-based representative large advanced PWR source term applied to the Sidi Boulbra candidate site on the Moroccan Atlantic coast. The analysis was performed with the HotSpot Health Physics Code using seasonal meteorological conditions derived from 30-year National Oceanic and Atmospheric Administration Integrated Surface Database (NOAA-ISD) records covering 1995-2024. The study quantified projected plume-centerline total effective dose equivalent (TEDE) for the modeled release and plume-passage period, including the 50-year committed inhalation dose component, ground-surface deposition, organ-specific committed dose equivalent, and precipitation effects. Under dry conditions, Scenario AS1 produced a maximum TEDE of 6.10 × 10-6 Sv, far below the supplementary comparison contour of 1.0 × 10-2 Sv. Scenario AS2 was controlling, with a maximum dry TEDE of 1.10 × 101 Sv and deposition of 2.50 × 107 kBq/m2 near 0.10 km under winter Pasquill-Gifford (PG) class D conditions. With 1 mm/h precipitation, AS2 reached 1.50 × 101 Sv and 1.90 × 108 kBq/m2. Inhalation contributed 77-79% of AS2 TEDE, and the thyroid was critical due to radioiodine uptake. The results identify sector-based plume tracking, inhalation-dose reduction, thyroid protection, ground surveys, and contamination control as priorities for further emergency-planning assessment.
Flexible composite materials with excellent mechanical properties that exhibit neutron moderation and absorption are required for effective neutron shielding in various applications. However, the addition of neutron absorbers may be detrimental to the overall mechanical properties of the materials. In this study, SiO2-reinforced natural rubber (NR/SiO2) vulcanizate with addition of Gd2O3 (NR/SiO2-Gd2O3) was investigated to develop a flexible material with good mechanical and neutron attenuation properties. NR/SiO2 and NR/SiO2-Gd2O3with Gd2O3 concentrations of 5-15 phr were fabricated and characterized for their curing, mechanical, physicochemical, and thermal neutron attenuation properties. The results show that the vulcanizates retained acceptable hardness, tensile strength, elongation at break, and tear strength despite the addition of Gd2O3, with only moderate decreases observed. SEM-EDS mapping confirmed that Gd2O3 and SiO2 were dispersed within the vulcanizate, although micro-agglomeration of Gd2O3 was observed in all samples. The beam hardening correction was applied to estimate the effective neutron attenuation value (Σeff) by linear regression of the experimental values (Σexp) against sample thickness. The Σeff for NR/SiO2 was 2.02 cm-1, whereas the values for NR/SiO2-Gd2O3 were 5.20-9.33 cm-1. These values correspond to an increase in Σeff by a factor of 2.5-4.6 with the addition of Gd2O3 at the investigated concentrations. The value for NR/SiO2 was in close agreement with the theoretical total macroscopic cross section, whereas NR/SiO2-Gd2O3 exhibited smaller values, likely due to the micro-agglomeration of Gd2O3. Nevertheless, the Σeff values were still greater than those of other reported NR vulcanizates.
This work quantifies the effect of shallow trench isolation (STI) guard ring separation (9, 8, 7, 6 and 5 μm) on afterpulsing in 180 nm CMOS SPADs subjected to neutron irradiation at a fluence of 4.29 × 1010 n/cm2. The afterpulsing probability is calculated with an analytical model using TCAD-extracted junction capacitance Cj and trapping/de-trapping parameters at an excess bias of Vex = 3.5 V. Decreasing the guard ring separation lowers Cj and the avalanche charge, giving a monotonic reduction in the pre-irradiation afterpulsing probability from 2.355% at 9 μm to 0.661% at 5 μm, evaluated over the 50 ns to 100 μs observation window. Adding the radiation-induced trap densities predicted by NIEL scaling raises the afterpulsing probability by 30.8% in the unannealed state, by an identical factor for every geometry within the present uniform-bulk-damage model. The results identify the guard ring separation as a geometric lever for capacitance-driven afterpulsing mitigation, show the trade-off between afterpulsing probability, fill factor and photon collection area, and provide layout guidance for radiation-tolerant SPADs. All results are obtained from the TCAD and analytical simulation in this work.
This study presents an optimized Monte Carlo model of an ORTEC GEM-series p-type coaxial high-purity germanium detector using PHITS and MCNP5, achieving mean relative differences in full-energy peak efficiency of approximately 2% across source-to-detector distances of 0 to 9 cm and gamma-ray energies from 59 keV to 1332 keV. By iteratively refining two critical geometric parameters (front dead-layer thickness optimized to 1.3 mm and crystal-to-endcap window distance optimized to 6.5 mm), the model successfully accounts for manufacturing tolerances and long-term dead-layer growth commonly observed in operational detectors. True coincidence summing effects in cobalt-60 were accurately reproduced for point and small-disk source geometries using PHITS' native correlated-emission capability and, alternatively, by applying correction factors derived from P-TReCK-TCS Monte Carlo software to conventional MCNP5 simulations; both approaches yielded nearly identical correction factors (average discrepancy approximately 0.3%) despite differences in geometric detail. The validated model provides a flexible, cost-effective alternative to repeated experimental calibrations with physical standards, enabling reliable efficiency predictions for various sample geometries and radionuclide mixtures in environmental monitoring, nuclear safeguards, and high-precision gamma-ray spectrometry applications.
The discovery of a Cesium-137 (Cs-137) radioactive source in the Modern Industrial Estate (KIM) Cikande, Indonesia, in 2025 highlighted the need to evaluate the potential atmospheric dispersion of radionuclides in industrial areas. This study aimed to investigate the influence of different meteorological datasets on the atmospheric dispersion of Cs-137 using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. A descriptive-comparative numerical simulation approach was employed using three meteorological datasets with different spatial resolutions: the Global Data Assimilation System (GDAS) 1°, GDAS 0.5°, and the Global Forecast System (GFS) 0.25°. The simulation outputs were evaluated based on plume direction, concentration distribution, affected area, hotspot identification, and peak concentration. The results showed that Cs-137 concentrations were highest near the release source and gradually decreased with increasing distance because of advection, turbulent diffusion, and atmospheric dilution. Higher-resolution meteorological datasets produced more detailed plume structures and improved hotspot identification, with GFS 0.25° producing the most spatially detailed plume representation among the datasets evaluated. However, the relative accuracy of the datasets could not be determined because independent meteorological and radiological observations were unavailable for validation for regional-scale assessments. Future studies should incorporate measured source-term data, field monitoring, and effective dose assessments to improve model validation and support more comprehensive radiological risk analyses and emergency preparedness planning.
This study assessed the activity concentrations of natural and artificial radionuclides and evaluated the associated radiological risks in soil and surface water samples collected from the Institute of Nuclear Medicine and Allied Sciences (INMAS) and the hospital premises of Rajshahi Medical College Hospital (RMCH), Bangladesh. Gamma-ray spectrometry and ArcGIS-based spatial mapping were employed to evaluate radiological conditions and associated health risks. The analysis included measurements of 226Ra, 232Th, 40K, 137Cs, 60Co and 131I in ten soil and ten water samples. The results demonstrated spatial variation in radionuclide distribution, although most values remained within internationally accepted radiological safety limits. In soil, mean activity concentrations at INMAS were 36.30 ± 6.52 Bqkg-1 (226Ra), 60.09 ± 8.64 Bqkg-1 (232Th), and 517.84 ± 55.23 Bqkg-1 (40K), exceeding those at RMCH (22.91 ± 6.17, 44.33 ± 8.11, and 468.45 ± 35.17 Bqkg-1, respectively). The distribution pattern (40K > 232Th > 226Ra) aligned with typical alluvial sediment geochemistry. In water, INMAS recorded lower activity concentrations of 226Ra (1.70 ± 0.19 Bqkg-1) and 232Th (2.14 ± 0.27 Bqkg-1) than RMCH (6.74 ± 1.08 and 5.33 ± 1.37 Bqkg-1, respectively), while 40K remained below detectable levels. No anthropogenic radionuclides (137Cs, 60Co and 131I) were detected of the gamma spectrometry system. Although certain soil samples exhibited outdoor absorbed dose rates, annual effective doses and excess lifetime cancer risk values slightly above global averages, others evaluated radiological hazard indices, including radium equivalent activity, external and internal hazard index, remained within internationally accepted safety limits for both soil and water. Scientific analysis confirms that the radiological profile of the Rajshahi medical-urban nexus is governed strictly by natural terrestrial radionuclides rather than medical-industrial discharges. Consequently, this study establishes a pristine "zero-point" radiological archive that is essential for distinguishing future industrial emissions from the existing geogenic background once the Rooppur Nuclear Power Plant becomes operational.
Technetium-99m, the most widely used diagnostic radioisotope in nuclear medicine, is obtained from the decay of molybdenum-99 produced by neutron irradiation of uranium-235. Annular low-enriched uranium (LEU) targets employ a thin metallic uranium foil positioned between concentric aluminum tubes, requiring effective consolidation to minimize interfacial gaps and maintain adequate heat transfer during irradiation. Traditionally, the consolidation is achieved mechanically using a draw plug. This study evaluates hydroforming as a technically feasible alternative that applies direct radial pressure while avoiding plug-tube sliding contact. A dedicated system was developed to apply pressures from 4 to 60 MPa, and residual gaps were measured circumferentially at one central axial cross-section. At 60 MPa, the two nickel-foil-wrapped targets exhibited average gaps of approximately 10.6 and 6.7 μm and maximum gaps of 16 μm. A target using electrodeposited nickel showed an average gap of 6.4 μm and a maximum gap of 12 μm. Relative to the nominal initial assembly clearances, the corresponding average-gap reductions were approximately 84%, 90%, and 91%. Hydroforming also eliminates the specific scratching and galling mechanism associated with direct draw-plug contact. However, a direct statistical comparison of average gaps with the previous draw-plug route is not possible because different sampling protocols were used. The electroplated condition was evaluated in only one specimen, and the measurements do not establish full axial uniformity. The results demonstrate technical feasibility and substantial local gap reduction, while target-specific thermal analysis, axial assessment, and post-irradiation disassembly qualification remain necessary.
Quantum dots (QDs) have been explored as active elements of scintillators, dosimeters and detectors for X-ray and gamma-ray ionizing radiation. This integrative review catalogued the computational simulation tools used in QD-detector studies published between 2018 and 2026, reporting the empirical evidence of use for each tool and the limitations declared by the original authors. Following Whittemore and Knafl's method combined with PRISMA-ScR reporting elements, five databases were queried (Scopus, Web of Science, PubMed, IEEE Xplore, and Google Scholar via Publish or Perish). The search yielded 4530 unique records after de-duplication, from which 35 studies were extracted through a structured form (30 fields): 34 published within the window plus one pre-window historical reference. The inventory distinguished two complementary classes: (A) twenty-four codes that model the QD itself (Table 5A), spanning ab initio, tight-binding, quantum transport and open-quantum-systems methods; and (B) fourteen Monte Carlo radiation-transport codes (Table 5B), namely Geant4, GATE 10, TOPAS, EGSnrc, PENELOPE, CASINO, FLUKA, MCNP/MCNPX, PHITS, TOPAS-nBio, Geant4-DNA, SSLG4, Chroma and optiGAN. Across the 35 studies, Geant4 was the most frequently declared radiation-transport engine (six studies). In the broader QD-modelling literature, VASP, Quantum ESPRESSO and DFTB + concentrated the atomistic parametrisation of II-VI and perovskite QDs. Each study declared between one and three tools, and explicit integration between radiation-transport engines and QD electronic-structure codes remained uncommon in the analysed literature. The consolidated inventory was intended as a reference for the QD-detector research community.
Dy2O3‒doped ZrO2‒PbO‒As2O3 glasses were synthesized via the conventional melt-quenching technique to investigate their structural, physical characteristics, Phy-X based radiation shielding, and dielectric properties. X‒ray diffraction confirmed the amorphous nature of all glass compositions, while energy-dispersive spectroscopy verified the successful incorporation of the constituent elements. The incorporation of Dy2O3 resulted in a systematic increase in density from 4.302 to 4.551 g/cm3, accompanied by increase oxygen packing density and a reduction in molar volume and inter-ionic separation, indicating enhanced structural compactness and possible Dy‒O interactions within the glass network. Radiation shielding parameters were evaluated using Phy-X/PSD software over a broad photon-energy range. The glass containing 1.0 mol% Dy2O3 exhibited the best shielding performance, with a linear attenuation coefficient of 377.72 cm-1, an effective atomic number of 43.76, and lower half-value layer and mean free path at 0.015 MeV, demonstrating improved γ-ray attenuation efficiency. The Energy-dependent variations of effective atomic number and electron density followed expected photon-matter interaction mechanisms, including photoelectric absorption, Compton scattering and pair production. Dielectric measurements performed over a wide frequency range revealed an enhanced dielectric constant with Dy2O3 addition up to an optimum concentration within the investigated range, attributed to increased ionic polarizability and network modification. Further, AC conductivity exhibited a typical frequency-dependent increase consistent with a hopping conduction mechanism in disordered oxide systems. The simultaneous enhancement in structural compactness, electronic response and radiation attenuation demonstrates that Dy2O3serves as an effective network modifier in ZrO2‒PbO‒As2O3 glass system, making these glasses promising candidates for radiation shielding and dielectric applications in nuclear and medical fields.
A recently synthesized lead-free PMMA nanocomposite modified with Bi2O3:SiO2 was assessed for its structural, optical, and radiation shielding qualities. The samples were synthesized using the process of solution casting at ambient temperature, with chloroform as a solvent. Bi2O3:SiO2 weight percentages of 5%, 10%, 15%, 20%, and 25% were progressively added to the dissolved PMMA of the nanocomposites. As the Bi2O3:SiO2 content increased, indirect and direct energy band gaps shrank from 5.57 to 2.54 and 4.64-2.69, respectively. On the other hand, as the concentration of Bi2O3:SiO2 increased, the refractive index rose from 1.92 to 2.53. The density of the samples increased from 2.729 g/cm3 for Pure PMMA to 3.631 g/cm3 for 25%, causing increase in LAC at all energy levels, which as an illustration, rises from 1.05 cm-1 for Pure PMMA to 1.707 cm-1 for 25% at 60 keV energy level, while from 0.146 cm-1 for Pure PMMA to 0.201 cm-1 for 25% at 1333 keV energy level. PMMA/25%Bi2O3:SiO2 demonstrated excellence shielding performance among other samples investigated, making it a potential candidate for radiation protection.
Radiation shielding is essential in nuclear energy, medical radiation facilities, space applications, and other environments exposed to ionizing radiation. Recent research has increasingly focused on improving shielding performance while reducing material weight, thickness, cost, and environmental impact. This review critically examines recent developments in radiation-shielding materials, with particular emphasis on radiation-shielding concrete, concrete aggregates, and predictive models used to evaluate and optimize their attenuation performance. The review summarizes the effects of aggregate composition, density, elemental constituents, microstructure, and material formulation on the attenuation of gamma and neutron radiation. Particular attention is given to experimental characterization methods and computational approaches, including attenuation measurements, spectroscopic and microstructural characterization, and Monte Carlo simulations, which provide complementary information on radiation transport and shielding effectiveness. Recent advances in the development of heavyweight, modified, and composite concretes are discussed, together with emerging approaches for improving shielding performance through optimized aggregate selection and concrete composition. The review also evaluates predictive and computational models developed to estimate key shielding parameters and support material optimization, highlighting their advantages and limitations relative to experimental measurements. Sustainable and locally available aggregate sources, as well as strategies for reducing shielding material requirements without compromising radiation protection, are also considered. By integrating experimental evidence with computational modeling, this review identifies current knowledge gaps and future research priorities for the development of high-performance and economically viable radiation-shielding concretes. Overall, the reviewed studies demonstrate that systematic control of aggregate characteristics, concrete composition, and predictive modeling can provide an effective pathway toward more efficient and application-specific radiation-shielding materials.
A novel polyacrylamide@vermiculite/lignin (PAA@VL) ternary composite was synthesized for the removal of UO22+ ions from aqueous solutions. FT-IR and SEM-EDX analyses confirmed the functional groups, heterogeneous layered morphology, and successful UO22+ adsorption of the composite. Bulk experiments showed that the adsorption process was affected by pH, initial concentration, dosage, temperature, and contact time. Isotherm studies showed that Langmuir and Freundlich models described the process well and that the maximum adsorption capacity was 2.15 mol kg-1. The high UO22+ removal performance of PAA@VL is attributed to the synergistic effect of its components, the abundant adsorptive sites, and a strong affinity for UO22+ ions. Thermodynamic findings indicate that a negative Gibbs energy (ΔG° = -55.0-54.4 kJ mol-1) suggests the adsorption process is spontaneous, a negative entropy change (ΔS° = -16.8 J mol-1 K-1) indicates a reduction in surface disorder on the composite, and a negative enthalpy value (ΔH° = -59.7 kJ mol-1) suggests the adsorption process is exothermic. The PAA@VL ternary composite shows strong potential as an efficient and sustainable adsorbent for UO22+ removal.
Previous published analyses of trinitite to determine the yield of the Trinity nuclear explosion used various estimates of the fraction of fission products that became incorporated in trinitite. Furthermore, these studies utilized nuclear data that has subsequently been revised. Utilizing a planar germanium detector, we observed gamma rays produced by the decays of both 137Cs and 239Pu from four samples of trinitite. From the observed 137Cs/239Pu ratios of and a simple analysis method based on current nuclear data and weapons debris studies, we find an average yield of 9.1 ± 4.5 kilotons from our four samples. While this result is substantially lower than the established total yield of 21 kilotons, it is in reasonable agreement that attributable to fissions in the 239Pu core alone.
In this work, the sorption behavior of Cs(I) onto Aspergillus Niger modified with zirconium molybdenum antimonate (ZrMoSb@AN) using the batch technique was studied. ZrMoSb@AN biosorbent was synthesized using the co-precipitation technique and characterized by different analytical tools, including scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray (EDX), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). According to the sorption results, the sorption process was carried out after 150 min to reach equilibrium. Reaction kinetics and sorption isotherms are more applicable to the pseudo-second-order model and the Langmuir isotherm with a maximum sorption capacity of 42.7 mg g-1. Thermodynamic data reveal that the sorption process is endothermic and spontaneous. Recovery of Cs(I) from the loaded ZrMoSb@AN was achieved using 0.1 M HCl. ZrMoSb@AN is a promising biosorbent for the retention of 134Cs from simulated radioactive waste containing major radionuclides such as 134Cs, 60Co, and 85Sr. The data revealed that ZrMoSb@AN could be considered an effective biosorbent for the retention of Cs(I) from aqueous solution.
In this study, a solution combustion approach was utilized to successfully produce Dy3+-doped LaBO3 phosphors. A comprehensive evaluation of their dosimetric capabilities, thermoluminescence (TL) features, and crystallographic properties was subsequently performed. The presence of a pure orthorhombic crystalline phase, free from any secondary formations, was verified through X-ray diffraction measurements. Elemental and morphological analyses utilizing EDX and SEM showcased the effective doping of Dy3+ into the lattice framework alongside a distinctly porous surface structure. We examined the impact of varying the Dy3+ dopant amounts from 0.25 to 7 wt%, discovering that the 1 wt% concentration yielded the maximum luminescent signal when monitored with a 565 nm filter. The glow curve of the optimum composition consisted of four prominent glow peaks, indicating the presence of trapping centers with different thermal stabilities. The beta dose response exhibited an almost ideal linear behavior between 0.1 and 30 Gy (b = 0.98, R2 = 0.99992), while a sublinear trend appeared at higher doses due to trap saturation effects. The phosphor demonstrated excellent reusability with a coefficient of variation close to 1% over ten irradiation-readout cycles. A minimum detectable dose of 0.09 ± 0.01 Gy and an effective atomic number of 50.31 were calculated, highlighting the high sensitivity of the material to ionizing radiation. Kinetic parameters determined with a method using the various heating rates presented corrected activation energies of 1.19, 1.60, 1.73, and 1.94 eV for the visible maxima. Thermal quenching analysis produced activation energies of 1.24 and 1.66 eV for the high-temperature peaks. Tm-Tstop, Initial Rise, and computerized glow curve deconvolution analyses consistently revealed a complex trapping structure composed of approximately eight discrete trap levels. The deconvolution fits resulted in low figure of merit (FOM) values of 2.24% and 0.82%, confirming the reliability of the deconvolution procedure and the extracted kinetic parameters. These findings demonstrate that LaBO3:Dy3+ is a promising thermoluminescent material for radiation dosimetry applications requiring high sensitivity and stable signal characteristics.
This study focuses on the determination of cytotoxicity and mutagenicity of Reactive Orange 122 dye (RO122). The ultraviolet (UV) and gamma (γ) radiations along with hydrogen peroxide (H2O2) were employed as an advanced oxidation process (AOPs). The 50 mg/L of dye solution were treated with UV radiation for 30-150 min and γ-ray absorbed doses (1-5 kGy) alone and in conjunction with H2O2. The untreated dye solutions have shown cytotoxicity and mutagenicity, which were decreased after treatment. The Allium cepa test showed 39.35, 46.16 and 52.44 (%) increase in root length (RL), root count (RC) and mitotic index (MI) for UV/H2O2-treated RO122 samples, whereas RL, RC and MI were increased up to 63.52, 70.32 and 89.98 (%), respectively for γ/H2O2 treatment. The brine shrimp assay has shown a reduction in mortality up to 82.95 and 91.30 (%) after UV/H2O2 and γ/H2O2 treatment, respectively. The hemolytic assay revealed a 32.5 and 62.4 (%) hemolysis for UV/H2O2 and γ/H2O2, respectively. The Ames test was performed using S. typhimurium strains to determine the mutagenicity of treated and untreated dye. The results indicated that cytotoxicity and mutagenicity of dye solutions were reduced following treatment with the selected AOPs. Further investigation into the scalability, energy efficiency and real wastewater applicability of these AOPs is recommended to facilitate their practical implementation in sustainable water treatment systems.
