Halide perovskite single crystals are emerging as great candidates for scintillation detection due to their remarkable luminescent properties. However, most halide single-crystals reported to date have been grown using the Bridgman method, and their crystal quality and properties are significantly affected by impurities, depending heavily on costly ultra-pure raw materials. Herein, we have developed an innovative water solution method enabling the growth of oversized (similar to 30 & times; 30 & times; 30 mm3) Cs2ZnCl4 single-crystal with natural crystal faces in water, achieving exceptional crystal quality (FWHM = 50.4'') without requiring ultra-pure raw materials, thereby effectively resolving the challenge of high-quality crystal growth for this single-crystal. In marked contrast to previously reported results, the Cs2ZnCl4 single-crystal grown exhibits a larger bandgap value (5.0 eV), distinctly different single-peak emission, higher light yield, and a fully ultrafast scintillation decay (1.8 ns). Additionally, we unexpectedly discovered that the grown Cs2ZnCl4 single-crystal exhibits high transmittance (similar to 90%) over an ultra-wide wavelength range of 260 nm to 15 & micro;m, highlighting its immense potential as a high-performance optical window material. This research highlights the successful growth of the first halide perovskite scintillation single-crystal (Cs2ZnCl4) in water, which will inform the future development of other high-performance scintillation crystals in aqueous environments.

Accurate localization of neutron sources in complex indoor environments is essential for nuclear security and radiological protection applications. Conventional inversion-based methods often suffer from structural scattering interference and lack systematic experimental validation in realistic indoor scenarios. To address these limitations, this study proposes a high-fidelity three-dimensional neutron source backtracking framework that combines a 3He proportional counter array with Geant4 Monte Carlo simulations. A dedicated experimental platform was constructed using modular 3He detection modules equipped with polyethylene moderators and a synchronized nuclear electronics chain. Measurements were performed under low-background laboratory conditions with integration times of 10 minutes per point. To enhance simulation fidelity, room-return effects arising from concrete floor and gypsum ceiling were explicitly incorporated into the simulation model, enabling realistic reproduction of neutron scattering within the laboratory. Based on extensive measurements under different source activities, a characteristic response function for 252Cf was obtained, yielding the calibration model [[EQUATION]].The simulated and experimental results showed strong consistency, with a mean absolute error of 9.67 for single-detector configurations. Fixed-point three-dimensional validation further demonstrated decimeter-level localization accuracy, with a mean positioning error of 17.93 cm. Given the 230 mm physical length of the 3He detectors, the achieved accuracy indicates effective use of the current hardware configuration's geometric capabilities. This work provides a validated computational and experimental framework for rapid localization of neutron sources in structurally complex indoor environments.

To enhance the efficiency of solving the two-dimensional neutron transport equation in cartesian coordinates, this paper employs the half-boundary method. It solves the relationship between neutron flux density values at internal and boundary points in the two-dimensional neutron transport model, followed by determining the distribution of neutron flux density throughout the entire model. Compared to traditional finite difference methods, HBM eliminates the need for solving large matrix inverse matrices as model discretization increases, thereby effectively reducing computation time and storage space requirements. This study utilizes four numerical examples to calculate results obtained using HBM and Monte Carlo methods, with previously obtained results serving as reference solutions. The impact of different spatial and angular discretizations on HBM numerical outcomes is analyzed to verify its accuracy. Consequently, it is concluded that accurate results can be achieved through the appropriate selection of discrete times when employing the half-boundary method.

The capture of volatile radionuclides such as iodine from nuclear waste gases is a significant challenging issue in the research field of nuclear energy.Metal-organic frameworks(MOFs)have shown great promise for iodine adsorption.The huge number of MOFs and their com-plex structures make traditional experi-mental and computational screening methods inefficient,whereas the ma-chine learning(ML)-based discovery of reliable MOFs for effective iodine capture is still in its infancy.Here we developed a ML mod-el to predict iodine adsorption capacity of MOFs using different input features.In particular,X-ray diffraction(XRD)spectra,which act as one type of input features,demonstrated an embedding relationship between high iodine adsorption capacity and low-angle XRD spectra.We further applied the constructed ML model to high-throughput screening and suggested several MOF materials for iodine capture.One of them,named MOF-143,was finally synthe-sized and characterized in experiments.

Neutron imaging technology is a crucial nondestructive testing technique widely used in nuclear, military, medical, and other fields. However, the development time of neutron imaging technology is relatively short, warranting further investigations in many aspects. In neutron imaging devices, the quality of the neutron-slowing collimator strongly affects both the imaging resolution and the required exposure time. Hence, developing and investigating neutron collimation systems are essential for the development of neutron imaging technology. Based on the shortcomings of the current common collimator structure, we propose a new collimator structure consisting of a circular tube-type collimator and an divergent collimator. Taking the reactor as the neutron source, a new neutron collimator system is studied and designed using the Geant4 program, and neutron slowing, collimation, and neutron gamma ratio improvement are studied and designed under this structure. The optimal selection and design of materials and structural dimensions of each part are completed. The designed device is compared with a conventional device, and simple thermal neutron radiography (TNR) is conducted. The simulation results show that the device has a collimation ratio of 62, a normalized thermal neutron flux of 2.07× 10^-6 cm^-2·s^-1 at the exit, an n/γ ratio of 4.01× 10^11 cm^-2·Sv^-1 , and the inhomogeneity of the radial distribution of neutrons is 7.5

The neutron distribution within a nuclear reactor core plays a crucial role in nuclear engineering, directly influencing the safe operation of nuclear reactors. The neutron transport equation provides a fundamental approach to determine this distribution. This study applies the half-boundary method (HBM) to solve the neutron transport equation in cylindrical coordinates. By deriving mathematical relationships among discrete nodal values, the HBM establishes explicit correlations between boundary conditions and neutron flux at arbitrary spatial points throughout the model. Compared to traditional finite difference methods, the HBM only requires iterative calculations on boundary values, thereby improving computational accuracy while reducing both execution time and memory requirements. In this paper, the HBM discretization and derivation processes are described in detail. The sensitivity analysis to assess the influence of varying the spatial and angular discretization parameters is made. Convergence analysis demonstrates that spatial discretization achieves secondorder accuracy in the radial direction, while angular discretization exhibits first-order convergence. Three numerical test cases are presented to verify the HBM by comparing its results with the Monte Carlo method, showing their consistency, high accuracy, and credibility.

High-resolution scintillation screens with superior light yield play a critical role in many applications. However, conventional single-crystal scintillators face limitations including challenges in ultra-thin precision fabrication, hygroscopic nature, and relatively low light yield, which hinder the development and application of high-resolution X-ray detectors. In this work, a Cs3Cu2I5-AAO scintillation screen is fabricated using a negative-pressure-assisted low-temperature solution synthesis method with an anodic aluminum oxide (AAO) template, which achieves ultra-bright luminescence with a light yield (LY) >70 000 photons/MeV and high spatial resolution (<20 & micro;m). Notably, in addition to the conventional self-trapped exciton (STE) emission (lambda(STE) = 450 nm), the scintillator exhibits an unprecedented ultrafast blue emission (lambda(BL) = 438 nm) with an average lifetime of tau(avg) = 2.279 ns. This phenomenon is reported for the first time in the Cs3Cu2I5 system. Based on reasoned speculation, we propose a surface V-I defect-assisted luminescence mechanism, attributing the fast emission (lambda(BL) = 438 nm) to the negative-pressure heating process during synthesis. Furthermore, the scintillator demonstrates consistent luminescence performance under intense irradiation conditions up to 563.5 mGy/s, indicating notable radiation resistance. These results highlight the promising potential of Cs3Cu2I5-AAO scintillation screens for applications in semiconductor defect inspection, biological tissue imaging, and 3D printing flaw detection.

The development of materials with low synthesis costs and high charge density for selectively removing radioactive pertechnetate anions (99TcO4- ) from contaminated groundwater is highly necessary. Here, we prepared ion-covalent organic polymers BBB-THB and DBB-THB featuring imidazole-N+-nanotraps through quaternization reactions involving 1,4-bis (bromomethyl) benzene (BBB), 1,4-dibromo-2,5-bis (bromomethyl) benzene (DBB), and 1,2,4,5-tetrakis (1H-imidazol-1-yl) benzene (THB). The synergistic interaction between the sigma-hole and steric effects of hydrophobic halogens enables selective trapping of perrhenate anions (ReO4-, a nonradioactive substitute for 99TcO4- ). BBB-THB and DBB-THB exhibited rapid removal kinetics (approximately 99% removal within 30 s) and substantial adsorption capacities (745 mg/g and 614 mg/g, respectively) in aqueous solutions containing ReO4- . Bromine-modified DBB-THB demonstrated superior adsorption performance across a broad pH range (pH 2-12) and exhibited enhanced hydrolytic stability and selectivity in strongly acidic solutions (1 M HNO3). Notably, in dynamic column experiments treating 10 mg/L ReO4-in Beishan groundwater at a high flow rate (0.5 mL/min), DBB-THB achieved a dynamic adsorption capacity of 11.86 mg/g, whereas BBB-THB yielded only 6.22 mg/g. Theoretical calculations elucidated the adsorption mechanism of ion exchange: the binding energy of 99TcO4- /ReO4- with the material exceeds that of NO3- , SO42- , etc. Selective recognition of 99TcO4-/ReO4-is achieved through the synergistic effects of electrostatic interactions and hydrophobic halogen sigma-hole and steric effects. More importantly, BBB-THB and DBB-THB had low synthesis costs, simple preparation processes, and fast adsorption rates, demonstrating their significant potential for large-scale treatment of groundwater contaminated with 99TcO4- .

Helical tubes are widely used due to compact structure, good thermal expansion and enhanced heat transfer performances. The characteristics of convection in helical tubes are more complicated than those in straight tubes due to centrifugal forces. In the literature, the viscosity ratio of μw/μb is used to consider the property variation effects of liquid on laminar convection in straight tubes. μw is the dynamic viscosity calculated by the wall temperature and μb is calculated by the bulk fluid temperature. However, investigations on property variation effects on laminar convection in helical tubes are fewer. In the current investigation, forced laminar convection of ethanol and water in helical tubes are simulated with Reynolds number ranging from 257 to 1852. Property variation effects on friction factor and Nusselt numbers in helical tubes are compared with the property variation effects in straight tubes. Based on analysis of order magnitude, the property variation effect ratio between convection in helical tubes and convection in straight tubes is related to the Nusselt number ratio with constant properties. Then, the correlation forms for friction factor and Nusselt number are obtained. Coefficients are determined by regression analysis of numerical results. The new friction factor and Nusselt number correlations show good prediction of numerical results and can be used for ethanol and water.

Uranium is crucial for the sustainable development of nuclear energy. The targeted design of novel adsorbents with high adsorption capacity and superior selectivity for uranium extraction remains a key challenge. Herein, we designed three types of amidoxime-based covalent organic polymers (COPs), named as DDBF-AO, TDBF-AO and HDBF-AO, by modulating hydroxyl density on the aromatic backbone of the materials. Systematical studies combining molecular dynamics (MD) simulations, density functional theory (DFT) calculations, experimental measurements and machine learning (ML) were carried out to elucidate the adsorption mechanism, with a specific focus on the role of hydroxyl groups and the dual-site synergy between hydroxyl and amidoxime groups. Our calculations confirmed that the hydroxyl groups promoted the conformational extension of the polymers and provided more accessible adsorption sites for electrostatic interaction with uranyl ions. Moreover, the synergistic effect between hydroxyl and amidoxime groups played a critical role in achieving high adsorption efficiency. Based on the theoretical guidance, we synthesized hydroxyl-modified TDBF-AO, which exhibited a higher uranium adsorption capacity (299.23 mg g- 1) compared to the DDBF-AO (155.48 mg g- 1). Furthermore, TDBF-AO displayed favorable adsorption kinetics and excellent ion selectivity, efficiently capturing U(VI) even in complex solutions. In alignment with experimental results, SHAP analysis of the ML model revealed that descriptors related to hydrophilicity and BET surface area were the most critical features governing adsorption capacity. Our findings highlight the value of ML in decoding structure-property relationships and provide a promising strategy of integrating theoretical prediction with experimental validation for the rational design of high-performance adsorbents in the application of uranium extraction.

The performance of various oxygen sensors in liquid lead-bismuth eutectic (LBE) alloy varies significantly across different temperature ranges. Therefore, it is necessary to establish a comprehensive temperature-related calibration database to achieve real-time dynamic calibration and compensation for sensor measurements. In this paper, multiple types of oxygen sensors have been developed based on 8YSZ ceramic tubes. The air reference (LSCF/Air, LSM/Air and Ag/Air) oxygen sensors and metal/metal oxide (Cu/Cu2O, Fe/Fe3O4, Ni/NiO, Bi/Bi2O3, and In/In2O3) reference oxygen sensors were tested under different temperature variations to obtain their operating characteristics in different temperature ranges. The air reference oxygen sensors have been demonstrated to exhibit excellent response speed, accuracy and stability within the range of 205 similar to 550 degrees C. The metal/ metal oxide reference oxygen sensor is more suitable for applications in the medium to high temperature range (>= 350 degrees C). It provides reference data for the operation of non-isothermal lead-bismuth system oxygen sensors.

In the coolant system of lead-based fast reactors, the liquid lead-bismuth eutectic (LBE) alloy exhibits a non-isothermal state, with significant temperature variations across different regions, imposing stringent requirements on the performance of oxygen sensors. The oxygen sensing output signal of metal/metal oxide reference electrode oxygen sensors exhibits notable attenuation at temperatures below 350 degrees C. The activity of noble metal Pt electrode oxygen sensors is significantly reduced under low-temperature conditions. To meet the oxygen measurement requirements under local extreme temperature conditions in LBE systems with oxygen control, it is necessary to develop oxygen sensors with a broader operational temperature range. This study focuses on the development of an air reference oxygen sensor by utilizing lanthanum strontium cobalt ferrite (LSCF) and lanthanum strontium manganite (LSM) from perovskite materials as reference electrodes, combined with 8YSZ (yttria-stabilized zirconia) solid electrolyte ceramic tubes. Tests under varying temperature conditions demonstrate that the LSCF electrode oxygen sensor achieves a maximum operating temperature of 700 degrees C, while the LSM electrode oxygen sensor attains a minimum operating temperature of 150 degrees C. This provides a wide temperature range oxygen measurement instrument suitable for non-isothermal LBE systems.

Shell and tube heat exchangers are widely used in nuclear engineering and the petrochemical industries. In the current investigation, cross flow over inline tube bundles with various pitch-to-diameter ratios is simulated by SST k-w-y. The mesh near the shear layer region is refined due to the large velocity gradient. The effects of the bounding wall, end wall, and pitch ratio on time-averaged and transient flow fields are systematically analyzed. The increased streamwise pitch results in the impinging point shifting to near B = 0 degrees. The increased transverse pitch results in a larger influence on side passages. The recirculation region near the end wall is attenuated, resulting in reduced drag and large velocity magnitude. The separated vortices after the middle tubes sway into the main flow. There is a separation vortex near the bounding wall due to the entrainment of separate vortices.

The application of liquid lead-bismuth eutectic (LBE) alloy coolant technology necessitates the implementation of real-time monitoring of dissolved oxygen concentration. Furthermore, in accordance with operational requirements, the dissolved oxygen concentration within the liquid LBE must be maintained within a reasonable target range. In order to enhance the provision of rapid and efficient oxygen replenishment to the liquid LBE loop, the oxygen supply behavior of the mass exchanger (MX) was modelled. The development of the oxygen control model of the MX was achieved by the collection of input (MX temperature) and output (signal of oxygen sensor) data from the solid-phase oxygen control experiments in the liquid LBE recirculation loop. The least squares method and neural network algorithm were utilised in the development of the oxygen control model, respectively. The findings demonstrate the efficacy of the oxygen control model in predicting the dissolved oxygen concentration within the LBE loop. This provides a theoretical framework for the subsequent optimisation of the solid-phase oxygen control strategy within the LBE system.

Rational design and synthesis of stable and efficient photocatalysts for selective U(VI) capture in water remains a great challenge due to the complicated water environment. Herein, considering the synergistic interaction between anthraquinone (-AQ, electron acceptor) and methoxy (-OCH3, electron donor), a series of ternary donor-acceptor-acceptor (D-A1-A2) covalent triazine frameworks named as OCH3(x)-AQ(y) (x and y represent different content ratios) were rationally designed and synthesized via molecular regulation. This work not only constructed a directional charge-transfer pathway, but also greatly improved the utilization efficiency of photogenerated electrons in OCH3(x)-AQ(y) framework, which was also further verified by density functional theory (DFT) calculations. Finally, OCH3(2)-AQ(3) could reach nearly 100% removal efficiency of U(VI) within 240 min under visible light irradiation in air. Meanwhile, OCH3(2)-AQ(3) showed an extremely high distribution coefficient (Kd, 1.07 × 106 mL·g-1) for U(VI) under multicomponent ion competition and further performed high removal efficiencies (>98%) in real water environments, such as seawater and groundwater. Importantly, the machine learning results also demonstrated that the structural characteristics would greatly influence the catalytic performance of CTF catalysts. The component tuning of donor-acceptor groups achieved synergistic effects in stepwise charge transport and target-selective site accessibility, which offered an effective photocatalytic strategy for U(VI) extraction in complex water environment.

The selective capture of 99TcO4- in extremely acidic and alkaline conditions remains a long-standing challenge in nuclear waste treatment. Herein, a strategy is proposed to rationally modulate polar substituents and spatial effects, resulting in the development of three ultra-stable cationic polymers, designated as V-P, V-3B, and V-YX. These polar-heterogeneous materials consistently achieve removal efficiencies exceeding 98.6% across a broad pH range (1-11), with saturated adsorption capacities of 1115.0, 655.1, and 871.4 mg g-1 for ReO4- (a nonradioactive surrogate for 99TcO4-), respectively. The phosphonium-functionalized V-P demonstrates exceptional suitability for capturing ReO4- from extremely acidic solutions and achieves a record-high capacity of 204.8 mg g-1 in long-term dynamic column experiments. Through the adjacent steric hindrance and unique electron-withdrawing effects in V-3B and V-YX, the alkaline stability of the imidazolium-N+ moiety is significantly enhanced, culminating in extraordinary ReO4- removal of approximate to 100% in 3 M NaOH solutions. In breakthrough experiments of simulated Beishan groundwater, V-3B and V-YX demonstrate dynamic capacities of 64.6 and 62.0 mg g-1, respectively. Molecular dynamics simulations and machine learning analyses further elucidate host-guest interaction mechanisms and the critical role of polar heterogeneity. These findings offer innovative and universal strategies for designing and screening materials tailored for radionuclide decontamination.

Two-dimensional (2D) nanomaterials display unique characteristics owing to their ultrahigh surface-to-volume ratio and quantum confinement effects. Nonetheless, seeking a versatile and facile method to rationally shape ultrathin 2D frameworks is still an appealing challenge. Herein, a series of ultrathin 2D metal oxide crystals (2D MOs), including 3d transition metals (Ti, Cr, Mn, Fe, Co, Ni, Cu, Zr, W), lanthanide (Ce) and nontransition metal (In, Sn, Bi) oxides, were created through a confined interlayer growth strategy in combination with melt infiltration, in which no complicated chemistry or sophisticated equipment was needed. The 2D oxides presented lamellar constructions with high crystallinity, and the thickness was strictly limited to similar to 1 nm. The crystallization process, including the Frank-van der Merwe mode and the Volmer-Weber mode, was described. The defects and distortions of 2D TiO2 reduced the optical band gap and improved the sunlight utilization efficiency, thus accelerating the photocatalytic activity. This method could be extended to the preparation of 2D polymetallic oxides, metal sulfides etc., which enables the development of versatile systems for ultrathin 2D frameworks, especially for nonlayered structures originally.

Vacuum ultraviolet (VUV) photodetection is pivotal for space exploration and radiation monitoring, yet its dynamic imaging capability is significantly hindered by the slow response of conventional scintillators. However, existing scintillators exhibit microsecond-to-nanosecond decay time, failing to meet sub-nanosecond ultrafast imaging demands. Here, we uncovered a surface exciton recombination mechanism in layered perovskite PEA2PbBr4, where lattice contraction induced exciton localization, achieving ultrafast decay time of 600 ps-over 100-fold faster than commercial scintillation. A reflective optical configuration was designed to suppress self-absorption, improving the light utilization efficiency. This work established a material paradigm for ultrafast dynamic imaging and opens avenues for advancing space science and high-energy physics detection.