Atomic Energy Research Articles

Predictive equation derived from 6,497 doubly labelled water measurements enables the detection of erroneous self-reported energy intake.

Nutritional epidemiology aims to link dietary exposures to chronic disease, but the instruments for evaluating dietary intake are inaccurate. One way to identify unreliable data and the sources of errors is to compare estimated intakes with the total energy expenditure (TEE). In this study, we used the International Atomic Energy Agency Doubly Labeled Water Database to derive a predictive equation for TEE using 6,497 measures of TEE in individuals aged 4 to 96 years. The resultant regression equation predicts expected TEE from easily acquired variables, such as body weight, age and sex, with 95% predictive limits that can be used to screen for misreporting by participants in dietary studies. We applied the equation to two large datasets (National Diet and Nutrition Survey and National Health and Nutrition Examination Survey) and found that the level of misreporting was >50%. The macronutrient composition from dietary reports in these studies was systematically biased as the level of misreporting increased, leading to potentially spurious associations between diet components and body mass index.

Beyond the Surface: Evaluating the Impacts of Fukushima Nuclear Wastewater Release

Following the 2011 Fukushima nuclear power plant accident in Japan, managing contaminated water became a long-term challenge. In August 2023, Japan began discharging treated atomic wastewater into the Pacific Ocean, sparking global concern. Since nuclear wastewater discharge involves environmental safety, public health, and international relations, understanding various perspectives and presenting scientific data is crucial for formulating reasonable policies. This study aims to analyse the attitudes of different countries towards the Fukushima nuclear wastewater discharge, assess its scientific basis, and explore its economic impact on Japan's fishing industry. The results show that Japan's wastewater discharge complies with international safety standards, based on an evaluation of publicly available data from the Tokyo Electric Power Company and the International Atomic Energy Agency. The analysis encompassed both safety measures and environmental impacts of this specific nuclear wastewater release. Despite scientific studies confirming that the treated nuclear wastewater meets safety standards, ongoing public concerns and geopolitical tensions have caused significant economic impacts on Japan's fishing industry. Therefore, enhanced scientific dialogue and research are needed to effectively address the potential long-term challenges that nuclear wastewater discharge may pose to marine ecosystems and global food safety

Radiological considerations in using uranium mine waste rock for road construction materials.

India's road construction is vital for its infrastructure growth, requiring approximately 20,000 tons of high-quality aggregates per kilometer - materials that are increasingly scarce, leading to higher costs and delays. The industrial sector, a cornerstone of the Indian economy, also struggles with waste management. Earlier studies suggested that industrial waste can be used in road construction materials however, the radiological considerations were not focused. This paper explores the potential of utilizing uranium mine waste rock in road construction materials. In the early stages of uranium mining in India, millions of tons of waste rock are generated and typically discarded, requiring extensive land and costly management. In this study, we assessed the radiological considerations in using waste rocks as road construction material generated from lean uranium ore. For this, a typical layered road design in India is adopted and dose rate were evaluated by QAD-CGGP code calculations and real-world measurements. Results indicate that the external radiation dose by using these waste rock in road construction materials remains below 1mSv/year for the public. The observed dose rate complies the National regulatory agency; Atomic Energy Regulatory Board criteria of 1 mSv/y for the unrestricted use of bulk materials in public domain. This approach not only addresses resource scarcity but also supports environmental sustainability by conserving natural resources, reducing ecological imbalances, and promoting a circular economy.

Etching Ceramic Samples with Fast Argon Atoms

A new approach to stripping surface layers from ceramics with fast atoms is proposed. The existing beam sources do not allow for a stripping rate of more than a few µm/h to be achieved. Usually, an increase in the etching rate is associated with growing flux density and energy of fast atoms, which can heat the parts of the beam source up to an inadmissible temperature. In the present work, the etching rate was significantly increased at permanent flux density and energy due to an increase in the angle of incidence of fast atoms on the product surface. An increase in the angle of incidence from zero to 80° resulted not only in an increase in the etching rate by several times but also in simultaneous polishing of the surface to a high finishing class.

Size-, shape-, facet- and support-dependent selectivity of Cu nanoparticles in CO2 reduction through multiparameter optimization.

This study investigates the limited selectivity of the Cu111 surface for C-C bond formation during CO2 reduction and explores the factors influencing selectivity using Cu nanoparticles smaller than 2 nm. The optimal nanoparticle size for C-C bond formation on the 111 facet with minimal overpotential is determined using density functional theory. A suitable supporting surface to enhance the stability and catalytic performance of the Cu-based nanoparticles is identified. Various Cu catalyst geometries, including planar surfaces and cuboctahedral, icosahedral, and truncated octahedral Cu nanoparticles, are considered. Size-dependent effects on the binding energies of reaction intermediates and hydrogen atoms are examined. Carbon-based surfaces, particularly 2SO2-doped graphene nanoribbons, are stable hosts for the Cu nanoparticles and help in retaining the activity for CO2 reduction. Scaling relations between the binding energies of the intermediates suggest COOH binding energy as an energy descriptor. Through multiparameter optimization and with the help of parity line and graphical construction, Cu38 and Cu79 are found to be the most promising surface for C2 product generation. This study provides insights into the factors influencing the selectivity and catalytic performance of Cu nanoparticles, aiding the development of efficient catalysts for CO2 reduction.

Estimation of Strontium-90 Concentrations in Pakistan Using Combination of TBP Solvent Extraction, Precipitation and Cherenkov Counting Methods

90Sr does not exist in nature. Its main sources in the environment are global fallout of past nuclear accidents or nuclear detonations. 90Sr is radiologically significant because of its relatively long physical and biological half-lives and its chemical resemblance to calcium. In order to estimate the radioactivity level of 90Sr around Pakistan Institute of Nuclear Science and Technology (PINSTECH) Islamabad, environmental samples (soil, water, vegetation, and water) and food samples (wheat, milk, poultry) were collected from the different selected sites around PINSTECH within the area of about 12.5 km radius. All samples were pretreated using the guidelines of International Atomic Energy Agency (IAEA) Technical Reports Series No. 295. 90Sr was indirectly determined through its progeny 90Y in secular radioactive equilibrium. 90Y was radiochemically separated using combination of Tri-n-butyl Phosphate (TBP) solvent extraction and precipitation. Finally, the activity was measured on Tri-Carb Liquid Scintillation Counter (LSC) through Cherenkov radiation. The activity concentrations of 90Sr in all samples were too low to be detected by the LSC system, except for a vegetation sample from Rawal Dam where a minimum activity of 0.16 ± 0.04 Bq/kg of fresh weight was found. No considerable activity concentration of 90Sr was found around PINSTECH research facilities.

Atomic Energy Optimization: A Novel Meta-Heuristic Inspired by Energy Dynamics and Dissipation

Atomic Energy Optimization: A Novel Meta-Heuristic Inspired by Energy Dynamics and Dissipation

Nondynamical correlation effects in multidimensional potential energy curves of prototypical hydrocarbons

We demonstrate that simultaneously stretching all bonds in a molecule by small increments provides a systematic approach to gradually increasing its multireference character. We show this for four hydrocarbons — methane, ethane, ethylene, and acetylene — each representing a progressively more complex electronic structure. The J1, D1, and %TAE[(T)] multireference diagnostics increase as all the bonds are stretched simultaneously. The post-CCSD(T) correlation components of the total atomization energy (TAE) up to CCSDTQ systematically increase as the bonds are stretched. The extent of the increase in the multireference character correlates with the complexity of the electronic structure in the order methane → ethane → ethylene → acetylene. The CCSDTQ/CBS multidimensional potential energy curves serve as benchmarks for assessing the performance of DFT methods for strong correlation effects. The conventional DFT methods B97-D, TPSS, and TPSSh and double-hybrid DFT methods are more robust toward multireference effects.

Simulation of Arc Discharge in an Argon/Methane Mixture, Taking into Account the Evaporation of Anode Material in Problems Related to the Synthesis of Functional Nanostructures.

In this work, within the framework of a self-consistent model of arc discharge, a simulation of plasma parameters in a mixture of argon and methane was carried out, taking into account the evaporation of the electrode material in the case of a refractory and non-refractory cathode. It is shown that in the case of a refractory tungsten cathode, almost the same methane conversion rate is observed, leading to similar values in the density of the main methane conversion products (C, C2, H) at different values of the discharge current density. However, with an increase in the current density, the evaporation rate of copper atoms from the anode increases, and a jump in the I-V characteristic is observed, caused by a change in the plasma-forming ion. This is due to the lower ionization energy of copper atoms compared to argon atoms. In this mode, an increase in metal-carbon nanoparticles is expected. It is shown that, in the case of a cathode made of non-refractory copper, the discharge characteristics and the component composition of the plasma depend on the field enhancement factor near the cathode surface. It is demonstrated that increasing the field enhancement factor leads to more efficient thermal field emission, lowering the cathode's surface temperature and the gas temperature in the discharge gap. This leads to the fact that, in the arc discharge mode with a cathode made of non-refractory copper, the dominant types of particles from which the synthesis of a nanostructure can begin are, in descending order, copper atoms (Cu), carbon clusters (C2), and carbon atoms (C).

In Ukrainian

The molecular models of tin dioxide nanoparticles containing 1 – 10 metal atoms and can include coordinated or constitutive water were constructed. Their equilibrium spatial structure and electronic structure are calculated using the second-order Möller – Plesset perturbation theory with the SBKJC valence basis set. It is shown that the length of the Sn–O bond in nanoclusters does not depend on their size and the coordination number of Sn atoms, but is determined by the coordination type of neighboring oxygen atoms. Namely, the Sn–O(3) bond length (~ 2.10 Å) > the Sn–O(2) bond length (~ 1.98 Å). The obtained Sn–O(3) bond lengths are in good agreement with the experimental values for crystalline SnO2 samples (2.05 Å). The calculated atomization energy for SnO2 is 1661 kJ/mol and satisfactorily corresponds to the experimentally measured specific atomization energy of crystalline SnO2 (1381 kJ/mol). It was found that a satisfactory reproduction of the experimental characteristics of crystalline tin dioxide is possible when using clusters containing at least 10 tin atoms, for example, (SnO2)10×14H2O. Based on the analysis of the energy effects of coordination of water molecules and hydroxide ion, proton removal and proton transfer on the hydrated surface of tin dioxide, quantitative estimates of the acid-base characteristics of the active centers of the SnO2 surface were made. The dependence of the acidity of hydroxyl groups and coordinated water molecules on the coordination number of the oxygen atom and the neighboring tin atom, as well as on the size of the cluster model, was revealed. It has been shown that the acidity of proton and aproton centers naturally decreases with increasing coordination number of the tin atom. The methodology used in this work to calculate the рКа value of the smallest model of the SnO2×H2O composition allows us to reproduce the experimental data for stannous acids. The mechanisms of formation of the simplest nanostructures from the initial forms of stannous hydroxide Sn(OH)4 are proposed. It has been shown that the formation of a dimer (SnO2)2×4H2O by the association of two Sn(OH)4 molecules is energetically most advantageous. Further transformations of nanoparticles lead to an increase in their size, dehydration, and the formation of denser structures that have crystallinity features inherent in solid-phase SnO2.

Soil Sampling Procedure for Management and Analysis of Legacy Sites in the Korean Peninsula

Background: The Korean Peninsula is split between the South Korea and Democratic People’s Republic of Korea (DPRK, North Korea), with North Korea possessing nuclear weapons. There are rising concerns over legacy sites, areas contaminated primarily by nuclear activities. In North Korea, these sites lack regulatory oversight and are likely neglected even if inactive. Hence, it is vital to devise strategies to manage and assess these sites. Yongbyon, a prominent nuclear site in North Korea, has been proposed for environmental sampling to gauge contamination levels. The goal is to determine contamination by suggesting sample collection points in Yongbyon.Materials and Methods: Using recent data and satellite imagery from the International Atomic Energy Agency’s periodic Safety Measures Report, we selected legacy sites to assess their contamination levels with recent data and satellite imagery. We identified sampling locations using the Visual Sample Plan (VSP) to check nuclear contamination. From these results, we devised a scenario evaluating accessibility and the local environment.Results and Discussion: For Yongbyon in North Korea, this study created two sampling scenarios based on interior access feasibility. Given North Korea’s constraints, we finalized the scenario without interior access. The sampling areas include two steam lines, four vehicle paths, and five green zones outside the facility.Conclusion: Nuclear facility operations worldwide are concerning. When halted, these become legacy sites requiring contamination management. Despite North Korea’s limited recordkeeping and challenges in determining contamination, we devised a sampling scenario using VSP software, factoring in accessibility and movement paths.

On machine learnability of local contributions to interatomic potentials from density functional theory calculations

Machine learning interatomic potentials, as a modern generation of classical force fields, take atomic environments as input and predict the corresponding atomic energies and forces. We challenge the commonly accepted assumption that the contribution of an atom can be learned from the short-range local environment of that atom. We employ density functional theory calculations to quantify the decay of the induced electron density and electrostatic potential in response to local perturbations throughout insulating, semiconducting and metallic samples of different dimensionalities. Molecules and thin layers are shown to fail keeping such disturbances localized. Therefore, the learnability of local atomic contributions, which guarantees scalability and transferability of a machine learning interatomic potential, is questionable in the case of molecules and low-dimensional samples. Similarly, the induced electrostatic effects due to substituted impurities or vacancy sites in a crystalline bulk are weakly damped and remain significant beyond several interatomic distances. However, geometric deformations in bulks are practically local within the first neighbors and induce a Yukawa-type electrostatic potential that exponentially vanishes. The practical importance of this finding is that it limits the application of the machine learning interatomic potentials to conformational search or thermal properties of bulk materials and so on, where only purely geometrical deformations are involved. Once chemically impactful defects like aliovalent impurities or vacancies are present, the interatomic potentials trained on local environments need to be corrected for long-range effects.

Phosphorus Doping Effects on the Optoelectronic Properties of K₂AgAsBr₆ Double Perovskites for Photovoltaic Applications

This work explores the modifications of optoelectronic properties in K₂AgAsBr₆ double perovskites induced by phosphorus doping. First-principles calculations using the CASTEP code with the PBE functional were carried out based on density functional theory (DFT). Our research investigates the electronic structure and optical behavior of the cubic Fm-3m phase of K₂AgAsBr₆, K₂AgAs₀.₈P₀.₂Br₆, and K₂AgAs₀.₆P₀.₄Br₆ to elucidate the impact of progressive phosphorus (P) substitution. P was chosen for its potential to modify the electronic structure due to its smaller atomic radius and different valence orbital energies compared to As. Our results reveal a systematic narrowing of the band gap with increasing P content, from 0.749 eV for the undoped compound to 0.587 eV for K₂AgAs₀.₈P₀.₂Br₆ and 0.424 eV for K₂AgAs₀.₆P₀.₄Br₆. This trend is attributed to the upward shift of the valence band maximum due to the higher energy of P 3p orbitals compared to As 4p orbitals. Analysis of the density of states confirms increased hybridization between P-p and As-p states at the valence band edge. Optical properties, including absorption coefficient, dielectric function, refractive index, and extinction coefficient, demonstrate a consistent red-shift and broadening of spectral features with P doping. Notably, P-substituted compounds exhibit enhanced absorption in the visible light region, with up to a 20% increase in the absorption coefficient at 550 nm for K₂AgAs₀.₆P₀.₄Br₆ compared to the undoped compound. This study reveals that elemental substitution offers a viable route to tailor optical and electronic properties of double perovskites, paving the way for the design of novel materials for next-generation photovoltaic and photoelectric devices.

Switchable Acidic Oxygen Evolution Mechanisms on Atomic Skin of Ruthenium Metallene Oxides.

RuO2 has been considered as a promising, low-cost, and highly efficient catalyst in the acidic oxygen evolution reaction (OER). However, it suffers from poor stability due to the inevitable involvement of the lattice oxygen mechanism (LOM). Here, we construct a unique metallene-based core-skin structure and unveil that the OER pathway of atomic RuO2 skin can be regulated from the LOM to an adsorbate evolution mechanism by altering the core species from metallene oxides to metallenes. This switch is achieved without sacrificing the number of active sites, enabling Pd@RuO2 metallenes to exhibit outstanding acidic OER activity with a low overpotential of 189 mV at 10 mA cm-2, which is 54 mV lower than that of the counterpart PdO@RuO2 metallenes. Additionally, they also exhibit robust stability with negligible activity decay over 100 h at 50 mA cm-2, outperforming most reported RuO2-based catalysts. Multiple spectroscopic analyses and theoretical calculations demonstrate that the Pd-metallene core, acting as an electron donor, increases the migration energy of subsurface oxygen atoms and optimizes the adsorption energy of intermediates on the active Ru sites, enabling a switch in the reaction mechanism. Such a unique metallene-based core-skin structure offers a novel way for tuning the catalytic behaviors of electrocatalysts.

Does Basis Set Superposition Error Significantly Affect Post‐CCSD(T) Corrections?

ABSTRACTWe have investigated the title question for both a subset of the W4‐11 total atomization energies benchmark, and for the A24x8 noncovalent interactions benchmark. Overall, counterpoise corrections to post‐CCSD(T) contributions are about two orders of magnitude less important than those to the CCSD(T) interaction energy. Counterpoise corrections for connected quadruple substitutions (Q) are negligible, and or especially so. In contrast, for atomization energies, the counterpoise correction can reach about 0.05 kcal/mol for small basis sets like cc‐pVDZ, thought it rapidly tapers off with cc‐pVTZ and especially aug‐cc‐pVTZ basis sets. It is reduced to insignificance by the extrapolation of applied in both W4 and HEAT thermochemistry protocols. In noncovalent dimers, the differential BSSE on post‐CCSD(T) correlation contributions is negligible even in basis sets as small as the unpolarized split‐valence cc‐pVDZ(no d).

Theoretical Study on the Adsorption of Hexavalent Chromium by Metal-Modified and Nitrogen-Doped Carbon Materials.

Cr(VI) can cause great harm to human beings and the environment and often exists in the form of HCrO4̅ in aqueous environments. The adsorption characteristics of HCrO4̅ on nitrogen-doped and iron-nickel-modified carbon substrates were systematically investigated using first principles. The properties of electron transfer and orbital hybridization of the substrates and HCrO4̅ during the adsorption process were analyzed by electron deformation density and density of states. The electrons were donated by the metal atoms and gained by the oxygen atoms involved in the adsorption of HCrO4-. The binding energies of the substrates and metal atoms were larger than the cohesive energies of the metal atoms, indicating excellent structural stability. Both mono- and bimetallic modifications of the carbon materials by Fe/Ni were favorable for the adsorption of HCrO4-. The increased number of doped nitrogen atoms could promote the adsorption. Among them, (Fe,Ni)/N-C possesses the optimal adsorption of HCrO4-, with an adsorption energy of -4.64 eV. This is mainly attributed to the fact that the Fe-Ni bimetallic atoms simultaneously participate in the electron transfer and orbital hybridization, providing a new perspective for the adsorption of Cr(VI) on bimetallic-modified substrates.

SOLEDGE3X full vessel plasma boundary simulations of ITER non-active phase plasmas

Abstract The onset of detachment in the ITER machine is analyzed in this work through the help of 2D-axisymmetric boundary plasma simulations with the SOLEDGE3X-EIRENE code, which features a numerical domain for the plasma solver extending up to the first wall. The plasma boundary is computed in scenarios from the first non-active phase of ITER, in pure H and at 20 MW. This set of simulations is used in two aspects: first, to study the plasma detachment in the divertor, and second, the plasma conditions, fluxes, and beryllium erosion at the first wall. Here, the code results are also compared to those obtained with the well-established SOLPS-ITER code, which includes a plasma numerical domain only covering the main SOL. Results show an increase in the SOL width $\lambda_q$ with increasing density, and a detailed analysis is carried out, for the first time, on each of the different plasma-neutral interactions in the code's physics model in EIRENE. The gross beryllium erosion rates of first wall panels are estimated from 2D simulations, with the aim of assessing their sensitivity to two parameters: the divertor density regime, and the presence of density shoulders in the far-SOL formed by enhanced perpendicular transport at this location. The erosion contributions from neutrals and ions are considered in each case, and the charge-exchange atoms fluxes and energy distributions are provided, highlighting the two atom populations (cold and charge-exchange).

Establishment of Local Diagnostic Reference Levels for Head CT Imaging in the Madina Region, Saudi Arabia.

Background: Computed Tomography (CT) is crucial in medical diagnosis, particularly for head examinations. Diagnostic Reference Levels (DRLs) are pivotal in balancing diagnostic efficacy with radiation safety. International organizations such as the International Atomic Energy Agency (IAEA) and the International Commission on Radiological Protection (ICRP) provide guidelines for establishing DRLs, emphasizing their importance in optimizing radiation doses. Aim: This study aimed to establish and standardize DRLs for head CT imaging in institutional and regional settings, emphasizing the need for tailored reference levels specific to each region's practices and standards. Method: Data collection included patient demographics, imaging parameters, and radiation dose indices, namely volume-weighted CT dose index (CTDIvol) and dose-length product (DLP). Statistical analyses were conducted to determine the median and 3rd quartile values for establishing DRLs. The results were compared with national and international benchmarks to assess variations in radiation doses across regions. Results: Demographic profiles detailed gender distributions and ages across hospitals. Imaging parameters exhibited variability in tube voltage, milliampere-seconds (mAs), pitch, scan length, and field of view (FOV). For CTDIvol, the 3rd quartile value was 65.8 mGy (range: 24.8-85.9 mGy), and for DLP, it was 1230.95 mGy·cm (range: 382.3-1189.0 mGy·cm). These values were slightly higher than the national DRLs for Saudi Arabia in 2021 and other international benchmarks, underscoring the need for further optimization and alignment of protocols. Conclusion: Optimizing and standardizing DRLs for head CT imaging is crucial for effectively managing radiation doses while ensuring diagnostic accuracy. Comparison with national and international benchmarks highlighted the importance of tailoring reference levels to regional practices and standards, ensuring patient safety without compromising diagnostic efficacy.

Enhancing puncture resistance in critical applications: A combined experimental and numerical approach

The qualification of materials for puncture resistance is essential for applications like pressure vessels and transport containers, particularly for the safe transport of radioactive materials. International regulations, set forth by organizations such as the International Atomic Energy Agency (IAEA) and the Atomic Energy Regulatory Commission (AERB), mandate the design of transport packages capable of withstanding various accident scenarios, including puncture, fire, impact, and immersion, to ensure the safety and integrity of radioactive material transport. This paper establishes a correlation between puncture energy ( E) required to penetrate stainless steel and mild steel plates, both with and without lead backing, as a function of plate thickness ( t) and punch diameter ( d). The simulation of strain and damage caused by punch impact is carried out within the elastoplastic region of structural materials, with a focus on the kinetic strengthening of the material. Abaqus finite element software is employed for numerical simulations, with model parameters derived from experimental stress-strain flow curve data using a curve-fitting technique. Dynamic compression experiments were conducted at the Refueling Technology Division (RTD) in the Bhabha Atomic Research Center (BARC) across a range of strain rates from 600 [Formula: see text] to 1750 [Formula: see text] at room temperature, using a Split Hopkinson Pressure bar. Additionally, drop weight tower (DWT) experiments were performed at RTD in the BARC facility to calibrate numerical simulations. These experiments were carried out on both bare and leaded stainless steel (SS304L) and mild steel (SA516Gr70) plates.

Bending Moiré in Twisted Bilayer Graphene.

Moiré potentials caused by lattice mismatches significantly alter electrons in two-dimensional materials, inspiring the discovery of numerous unique physical properties. While strain modulates the structure and symmetry of the moiré potential, serving as a tuning mechanism for interactions, the impact of out-of-plane deformation, e.g., bending, on the moiré superlattice remains unknown. Here, we performed large-scale molecular dynamics simulations to study the evolution of the moiré superlattice of twisted bilayer graphene under out-of-plane bending deformation. Our findings indicated that curvature-dependent bending caused both global and local lattice structure modifications in the moiré superlattice. We revealed a linear relationship between lattice displacement and bending curvature across varying initial twist angles along with precise regulation of local interlayer rotation. Additionally, the atomic potential energy landscape revealed that the localized atomic stacks underwent a whirlpool-like transformation, becoming a relaxed superlattice. This work opens up new opportunities for tailoring moiré superlattices by using out-of-plane bending engineering.