• Carbon-based nanomaterials cause toxicity by oxidative stress to the liver and brain in Sprague–Dawley rats

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-11

    摘要: Carbon-based nanomaterials have important research significance in various disciplines, such as compositematerials, nanoelectronic devices, biosensors, biological imaging, and drug delivery. Recently, the human andecological risks associated with carbon-based nanomaterials have received increasing attention. However, thebiosafety of carbon-based nanomaterials has not been investigated extensively. In this study, we used differenttypes of carbon materials, namely, graphene oxide (GO), single-walled carbon nanotubes (SWCNTs), and multiwalledcarbon nanotubes (MWCNTs), as models to observe their distribution and oxidative damage in vivo.The results of Histopathological and ultrastructural examinations indicated that the liver and lungs were the mainaccumulation targets of these nanomaterials. SR-μ-XRF analysis revealed that SWCNTs and MWCNTs mightbe present in the brain. This shows that the three types of carbon-based nanomaterials could cross the gas–bloodbarrier and eventually reach the liver tissue. In addition, SWCNTs and MWCNTs could cross the blood–brainbarrier and accumulate in the cerebral cortex. The increase in ROS and MDA levels and the decrease in GSH,SOD, and CAT levels indicated that the three types of nanomaterials might cause oxidative stress in the liver.This suggests that direct instillation of these carbon-based nanomaterials into rats could induce ROS generation.In addition, iron (Fe) contaminants in these nanomaterials were a definite source of free radicals. However,these nanomaterials did not cause obvious damage to the rat brain tissue. The deposition of selenoprotein inthe rat brain was found to be related to oxidative stress and Fe deficiency. This information may support thedevelopment of secure and reasonable applications of the studied carbon-based nanomaterials.

  • On the accuracy and efficiency of the reactor operation digital twin for parameter identification and state estimation

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-08

    摘要: Accurate and efficient online parameter identification and state estimation are crucial for leveraging Digital Twin simulations to optimize the operation of near-carbon-free nuclear energy systems. In previous studies, we developed a reactor operation digital twin (RODT). However, non-differentiabilities and discontinuities arise when employing machine-learning-based surrogate forward models, challenging traditional gradient-based in verse methods and their variants. This study investigated deterministic and metaheuristic algorithms and developed hybrid algorithms to address these issues. An efficient modular RODT software framework that incorpo rates these methods into its post-evaluation module is presented for comprehensive comparison. The methods were rigorously assessed based on convergence profiles, stability with respect to noise, and computational performance. The numerical results show that the hybrid KNNLHS algorithm excels in real-time online applications, balancing accuracy and efficiency with a prediction error rate of only 1% and processing times of less than 0.1 s. Contrastingly, algorithms such as FSA, DE, and ADE, although slightly slower (approximately 1 s), demonstrated higher accuracy with a 0.3% relative L2 error, which advances RODT methodologies to harness machine learning and system modeling for improved reactor monitoring, systematic diagnosis of off-normal events, and lifetime management strategies. The developed modular software and novel optimization methods presented offer pathways to realize the full potential of RODT for transforming energy engineering practices. 

  • 乏燃料储存用中子/γ射线屏蔽材料研究进展

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-02

    摘要: 随着核工业的发展,核电站产生的乏燃料因其高放射性而引起人们的关注,如何保证核设施的可靠运行和工作人员的安全占据着至关重要的地位。为了避免致命的辐射,已经开发了许多功能性中子/γ射线屏蔽材料。本文回顾了用于乏燃料储存用的不同中子/γ射线屏蔽材料的研究进展,包括硼化不锈钢、含Gd复合材料、B4C/Al复合材料、含铅、钨的复合材料。分别介绍了中子/γ射线屏蔽材料的优缺点,并提出后续乏燃料储存用的中子/γ射线屏蔽材料的研发思路。

  • 贝塔衰变实验中电子对伽马全吸收谱的影响

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-01

    摘要: 贝塔奥斯陆实验方法为研究高激发态下的放射性核素性质以及探究从铁到铀的元素核合成过程提供了一种重要的研究工具。本文提出了一种新型数据处理技术,旨在消除贝塔衰变电子对贝塔奥斯陆实验中了子核伽马退激衰变探测的影响,从而准确地展开观测到的伽马射线光谱。通过运用伽马射线与衰变电子的综合探测器响应函数矩阵,将列主元消去法与逐步迭代反解法相结合,确定真实的入射伽马光谱。通过模拟和反演计算,证实了所提出方法的可靠性与有效性。

  • 脉冲电流作用下纯铁及RPV钢缺陷“修复”的正电子湮没研究

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-05-01

    摘要: 为探究电脉冲处理(Electropulsing treatment,简称EPT)对金属材料缺陷的修复作用,设计了一套电脉冲处理设备和与其配套的处理方法,并对电子辐照样品与拉伸样品等含有缺陷的金属材料进行电脉冲处理。利用正电子谱学对原子尺度缺陷的十分灵敏的特点,对电脉冲处理后样品进行正电子寿命谱等表征,获得纯铁及RPV钢辐照或形变产生缺陷可通过电脉冲处理部分“修复”,缺陷“修复”的效果既与样品初始状态有关,又与电脉冲处理参数有关,正电子湮没作为新的无损检测方法有望给出脉冲电流作用下材料损伤或缺陷“修复”的判据,可方便、快速及高灵敏探测实际工况部件的缺陷状态。

  • Transverse Mode-Coupling Instability with Longitudinal Impedance

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-30

    摘要: Transverse mode-coupling instability (TMCI) is a dangerous transverse single-bunch instability that can leadto severe particle loss. The mechanism of TMCI can be explained by the coupling of transverse coherentoscillation modes owing to the transverse short-range wakefield (i.e., the transverse broadband impedance).Recent studies on future circular colliders, e.g., FCC-ee, showed that the threshold of TMCI decreased significantlywhen longitudinal and transverse impedances were included. We performed computations for a circularelectron-positron collider (CEPC) and observed a similar phenomenon. Systematic studies on the influence oflongitudinal impedance on the TMCI threshold were conducted. We concluded that the imaginary part of thelongitudinal impedance, which caused a reduction in the incoherent synchrotron tune, was the primary reasonfor the reduction in the TMCI threshold. Additionally, the real part of the longitudinal impedance assists inincreasing the TMCI threshold.

  • Quick-scanning X-ray Absorption Fine Structure Beamline at SSRF

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-29

    摘要: The layout and characteristics of the hard X-ray spectroscopy beamline (BL11B) at the Shanghai Synchrotron Radiation Facility are described herein. BL11B is a bending-magnet beamline dedicated to conventional millisecond-scale quick-scanning X-ray absorption fine structures. It is equipped with a cylindrical collimating mirror, a double-crystal monochromator comprising Si(111) and Si(311), a channel-cut quick-scanning Si(111) monochromator, a toroidal focusing mirror, and a high harmonics rejection mirror. It can provide 5–30 keV of X-rays with a photon flux of ~5 × 1011 photons/s and an energy resolution of ~ 1.31 × 10-4 at 10 keV. The performance of the beamline can satisfy the demands of users in the fields of catalysis, materials, and environmental science. This paper presents an overview of the beamline design and a detailed description of its performance and capabilities.

  • One-neutron stripping process in the 209Bi(6Li, 5Li)210Bi* reaction

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-29

    摘要: One-neutron stripping process between 6Li and 209Bi was studied at 28, 30, and 34 MeV using the in-beam γ-ray spectroscopy method. The γ-γ coincident analysis clearly identified two γ-rays feeding the ground and long-lived isomeric states, which were employed to determine the cross section. The one-neutron stripping cross sections were similar to the cross sections of complete fusion in the 6Li+209Bi system, but the one-neutron stripping cross sections decreased more gradually at the sub-barrier region. A coupled-reaction-channel calculation was performed to study the detailed reaction mechanism of the one-neutron stripping process in 6Li. The calculations indicated that the first excited state of 5Li is critical in the actual one-neutron transfer mechanism, and the valence proton of 209Bi can be excited to the low-lying excited state in (6Li, 5Li) reaction, unlike in the (d,p) reaction.

  • Ultrahard X-ray Multifunctional Application Beamline at the SSRF

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-29

    摘要: The Ultrahard X-ray Multifunctional Application Beamline (BL12SW) is one of the Phase-II Beamline Projects at the Shanghai Synchrotron Radiation Facility. The primary X-ray techniques used at the beamline are high-energy X-ray diffraction and imaging using white and monochromatic light. The main scientific objectives of ultrahard X-ray beamline are focused on two research areas. One is the study of the structural properties of Earth’s interior and new materials under extreme high-temperature and high-pressure conditions, and the other is the characterization of materials and processes in near-real service environments. The beamline utilizes a superconducting wiggler as the light source, with two diamond windows and SiC discs to filter out low-energy light (primarily below 30 keV) and a Cu filter assembly to control the thermal load entering the subsequent optical components. The beamline is equipped with dual monochromators. The first was a meridional bending Laue monochromator cooled by liquid nitrogen, achieving a full-energy coverage of 30–162 keV. The second was a sagittal bending Laue monochromator installed in an external building, providing a focused beam in the horizontal direction with an energy range of 60–120 keV. There were four experimental hutches: two large volume press (LVP) experimental hutches (LVP1 and LVP2) and two engineering material (ENG) experimental hutches (ENG1 and ENG2). Each hutch was equipped with various near-real service conditions to satisfy different requirements. For example, LVP1 and LVP2 were equipped with a 200-ton DDIA press and a 2000-ton dual-mode (DDIA and Kawai) press, respectively. ENG1 and ENG2 provide in-situ tensile, creep, and fatigue tests as well as high-temperature conditions. Since June 2023, the BL12SW has been in trial operation. It is expected to officially open to users by early 2024.

  • In-situ measurement via the flow-through method and numerical simulations for radon exhalation during measurements of the radon exhalation rate

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-26

    摘要: Small-scale measurements of the radon exhalation rate using the flow-through and closed-loop methods were conducted on the surface of a uranium tailing pond to better understand the differences between the two methods.An abnormal radon exhalation behavior was observed, leading to computational fluid dynamics (CFD)-based simulations in which dynamic radon migration in a porous medium and accumulation chamber was considered.Based on the in-situ experimental and numerical simulation results, variations in the radon exhalation rate subject to permeability, flow rate, and insertion depth were quantified and analyzed. The in-situ radon exhalation rates measured using the flow-through method were higher than those measured using the closed-loop method, which could be explained by the negative pressure difference between the inside and outside of the chamber during the measurements. The consistency of the variations in the radon exhalation rate between the experiments and simulations suggests the reliability of CFD-based techniques in obtaining the dynamic evolution of transient radon exhalation rates for diffusion and convection at the porous medium–air interface. The synergistic effects of the three factors (insertion depth, flow rate, and permeability) on the negative pressure difference and measured exhalation rate were quantified, and multivariate regression models were established, with positive correlations in most cases; the exhalation rate decreased with increasing insertion depth at a permeability of 1×10−11 m2. CFD-based simulations can provide theoretical guidance for improving the flow-through method and thus achieve accurate measurements

  • Superhydrophobic melamine sponge prepared by radiation induced grafting technology for efficient oil-water separation

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-26

    摘要: 本文介绍了一种超疏水性三聚氰胺(ME)海绵(ME-g-PLMA),该海绵通过高能辐射诱导的原位共价接枝长烷基十二烷基甲基丙烯酸酯(LMA)到ME海绵上,以实现高效的油水分离。所得的ME-g-PLMA海绵具有优良的孔隙结构,具有超疏水性(水接触角为154°)和超亲油性,可吸收高达自身重量66-168倍的各类油脂。所得到的ME-g-PLMA海绵可以通过连接泵连续分离水面上的浮油,或者通过重力驱动装置分离水下的浮油。ME-g-PLMA海绵在长期浸泡在不同的腐蚀性溶液中,多次反复吸油后,也能保持其高疏水性。所得改性ME-g-PLMA海绵具有优异的分离性能,在溢油清理方面具有巨大的潜力。

  • Surface Diffraction Beamline at the SSRF

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-26

    摘要: BL02U2 of the Shanghai Synchrotron Radiation Facility (SSRF) is a surface diffraction beamline with a photon flux of 5.5 × 1012 photons/s at 10 keV and a beam size of 160×80 µm2 at the sample site. It is dedicated to studying surfaces (solid–vacuum, solid–gas) and interfaces (solid–solid, solid–liquid, and liquid–liquid) in nanoscience, condensed matter, and soft matter systems using various surface scattering techniques over an energy range of 4.8–28 keV with transmission and reflection modes. Moreover, BL02U2 has a high energy resolution, high angular resolution, and low beam divergence, which can provide excellent properties for X-ray diffraction experiments, such as grazing incident X-ray diffraction, X-ray reflectivity, crystal truncation rods, and liquid X-ray scattering. Diversity of in-situ environments can also be provided for the samples studied. This paper describes the setup of the new beamline and its applications in various fields.

  • BL03HB:A Laue microdiffraction beamline for both protein crystallography and materials science at SSRF

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-25

    摘要: A Laue microdiffraction beamline (BL03HB) was constructed at the Shanghai Synchrotron Radiation Facility (SSRF). This beamline features two consecutive focusing points in two different sectors within its end station, the first dedicated to protein crystallography and the other tailored to materials science applications. Based on a superbend dipole magnet with a magnetic field of 2.29 T, a two-stage focusing design was implemented with two sets of Kirkpatrick–Baez mirrors to achieve a micro white beam as small as 4.2×4.3 µm 2 at the first sector and 0.9×1.3 µm 2 at the second sector in the standard beamline operation mode at SSRF. The X-ray microbeam in the two sectors can be easily switched between monochromatic and white beams by moving a four-bounce monochromator in or out of the light path, respectively. In the protein crystallography sector, white-beam Laue microdiffraction was demonstrated to successfully determine the structure of protein crystals from only a few images of diffraction data collected by a Pilatus 2M area detector. In the materials science sector, the white-beam Laue diffraction was collected in a reflection geometry using another Pilatus 2M area detector, which could map the microstructural distribution on the sample surface by scanning the samples. In general,the BL03HB beamline promotes the application of Laue microdiffraction in both protein crystallography and materials science. This paper presents a comprehensive overview of the BL03HB beamline, end station, and the first commission results.

  • An improved analysis method for assessing the nuclear-heating impact on the stability of toroidalfield magnets in fusion reactors

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-19

    摘要: The superconducting magnet system of a fusion reactor plays a vital role in plasma confinement, a processthat can be disrupted by various operational factors. A critical parameter for evaluating the temperature marginof superconducting magnets during normal operation is the nuclear heating caused by D-T neutrons. This studyinvestigates the impact of nuclear heating on a superconducting magnet system by employing an improvedanalysis method that combines neutronics and thermal hydraulics.In the magnet system, toroidal field (TF) magnets are positioned closest to the plasma and bear the highestnuclear-heat load, making them prime candidates for evaluating the influence of nuclear heating on stability.To enhance the modeling accuracy and facilitate design modifications, a parametric TF model that incorporatesheterogeneity is established to expedite the optimization design process and enhance the accuracy of the computations. A comparative analysis with a homogeneous TF model reveals that the heterogeneous model improvesaccuracy by over 12%. Considering factors such as heat load, magnetic-field strength, and cooling conditions,the cooling circuit facing the most severe conditions is selected to calculate the temperature of the superconductor. This selection streamlines the workload associated with thermal-hydraulic analysis. This approach enablesa more efficient and precise evaluation of the temperature margin of TF magnets. Moreover, it offers insightsthat can guide the optimization of both the structure and cooling strategy of superconducting magnet systems.

  • Calculation of microscopic nuclear level densities based on covariant density functional theory

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-12

    摘要: A microscopic method for calculating nuclear level density (NLD) based on the covariant density functional theory (CDFT) is developed. The particle-hole state density is calculated by combinatorial method using the single-particle levels schemes obtained from the CDFT, and then the level densities are obtained by taking into account collective effects such as vibration and rotation. Our results are compared with those from other NLD models, including phenomenological, microstatistical and non-relativistic HFB combinatorial models. The comparison suggests that the general trends among these models are basically the same, except for some deviations from different NLD models. In addition, the NLDs of the CDFT combinatorial method with normalization are compared with experimental data, including the observed cumulative number of levels at low excitation energy and the measured NLDs. Compared with the existing experimental data, the CDFT combinatorial method can give reasonable results.

  • Cross section determination of 27Al(n,2n)26Al reaction induced by 14 MeV neutrons uniting with D-T neutron activation and AMS techniques

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-11

    摘要: Aluminum is the primary structural material in nuclear engineering, and its cross-section induced by 14 MeV neutrons is of great significance. To address the issue of insufficient accuracy for the 27Al(n,2n)26Al reaction cross-section, the activation method and accelerator mass spectrometry (AMS) technique were used to determine the 27Al(n,2n)26Al cross-section, which could be used as a D-T plasma ion temperature monitor in fusion reactors. At the China Academy of Engineering Physics (CAEP), neutron activation was performed using a K-400 neutron generator produced by the T(d,n)4He reaction. The 26Al/27Al isotope ratios were measured using the newly installed GYIG 1 MV AMS at the Institute of Geochemistry, Chinese Academy of Sciences. The neutron flux was monitored by measuring the activity of 92mNb produced by the 93Nb(n,2n)92mNb reaction. The measured results were compared with available data in the experimental nuclear reaction database, and the measured values showed a reasonable degree of consistency with partially available literature data. Thenewly acquired cross-sectional data at 12 neutron energy points through systematic measurements clarified the divergence, which has two different growth trends from the existing experimental values. The obtained results are also compared with the corresponding evaluated database, and the newly calculated excitation functions with TALYS-1.95 and EMPIRE-3.2 codes, the agreement with CENDL-3.2, TENDL-2021 and EMPIRE-3.2 results are generally acceptable. A substantial improvement in the knowledge of the 27Al(n,2n)26Al reaction excitation function was obtained in the present work, which will lay the foundation for the diagnosis of the fusion ion temperature, testing of the nuclear physics model, and evaluation of nuclear data, etc.

  • 核天体物理实验中的原位正电子湮灭测量方法

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-10

    摘要: 在核天体物理关心的热核反应中,有一些可以产生短寿命的正电子放射性产物,这些反应产物发射的正电子会在靶中与电子发生湮灭,继而产生一对能量为511 keV的γ射线,可以通过测量这一对γ射线来得到反应产额,从而计算出核反应截面以及天体物理S因子。以往的实验通常将靶辐照后转移到屏蔽体内进行离线活度测量,近期有研究提出了在实验终端上原位测量正电子湮灭的方法,该方法主要是借助511 keV-511 keV γ射线对的方向相反特性,利用探测阵列的对向单元进行空间符合测量,压制本底干扰。本文基于近期自主研发的大型模块化BGO阵列LAMBDA-II,在地面实验室利用强流质子束打靶,对这一方法进行了实验研究和验证,为将来进一步将该方法应用到核天体物理研究中奠定了良好的基础。

  • GEM元素俘获测井在页岩储层古沉积环境辨识中的应用

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-09

    摘要: 元素俘获测井可以获取地层中的岩石元素含量,为了查明页岩气储层发育和展布规律,以中扬子地区保靖区块寒武统牛蹄塘组首口页岩气参数井—BY2井为研究对象,通过对元素俘获测井资料的解释和处理,获取精准的页岩储层元素组成及含量,建立牛蹄塘组地球化学指标剖面,利用元素地球化学指标开展古沉积环境的辨识和反演。研究结果表明:牛蹄塘组页岩中元素以Si、Al、Fe为主,少量的K、Ca、Mg、S等,页岩中Si、Fe、S等元素含量较高,页岩可压性较好;牛蹄塘组页岩属活动大陆边缘沉积,沉积物源岩的原始物质应来自西北端康滇古陆,基本为活动大陆构造带、有热液参与的正常沉积,牛蹄塘组上段沉积期气候干燥,为缺氧的滞留盆地边缘缓坡沉积,水体盐度高,陆源供给充分,古生产力低下;牛蹄塘组下段沉积期气候湿润,为深水滞留型盆地沉积,陆源供给不足,水体盐度较高,具有较高的古生产力,有利于有机质的形成,水体环境以贫氧相为主,有利于有机质保存,为页岩气形成和富集的有利沉积环境。

  • HWR019超导腔氦压敏感系数模拟优化

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-08

    摘要: 中国加速器驱动嬗变研究装置(CiADS)的超导直线段运行在连续波模式下,4K液氦压强波动导致超导腔体产生形变而失谐是影响低β腔稳定运行的重要因素。针对半波长超导谐振腔受氦压波动影响而运行不稳定的问题,以CiADS超导直线段β=0.19的半波长超导谐振腔(HWR019)为例,采用数值模拟的方法对液氦压强波动与该腔的频率变化规律进行仿真研究。通过对腔液氦接触区域、腔体的壁厚、液氦冷却流道的形状与腔体氦压敏感系数(KPrees)之间的关系进行计算分析,实现了将HWR019超导腔KPress值降为接近0的目的;同时通过对腔体进行热力学计算,提供了相应的强化传热方案,有效地降低了超导腔在运行过程中的最高温度,保证了CiADS装置对超导腔稳定运行的需求,其分析优化方法对同类型的低β超导腔也具有借鉴意义。

  • HIAF-BRing 四极铁钛合金内衬真空管道宽带阻抗研究

    分类: 核科学技术 >> 辐射物理与技术 提交时间: 2024-04-08

    摘要: 超薄壁钛合金内衬不锈钢真空管道以其结构强度高,横向孔径小,适合于极高真空环境,在快上升磁场中的涡流效应处于可接受范围内,与其他类型的磁场快变化磁铁的真空管道相比成本较低等原因,已经成为HIAF-BRing二极磁铁和四极磁铁真空管道方案的首选。二极铁和四极铁钛合金内衬真空管道是BRing中重要的束流耦合阻抗源。其中,四极铁钛合金内衬的阻抗及其减小措施尚未研究过。在模拟软件CST studio suite中使用传输线法和尾场法分别对各种规格的四极铁钛合金内衬真空管道进行模拟,模拟结果表明1—500 MHz频段内钛合金内衬真空管道主要引入宽带阻抗,且钛合金内衬内表面加薄板的阻抗减小措施同样适用于四极铁真空管道。利用模拟结果计算全环阻抗,发现在106—5x108Hz频段内,钛合金内衬真空管道采取阻抗减小措施能将全环横向宽带阻抗虚部从0.70MΩ/m(水平)和0.82MΩ/m(垂直)减小到0.33MΩ/m(水平)和0.43MΩ/m(垂直),将此结果代入DELPHI中计算78Kr19+单个束团在不同流强下的模式频率移动,发现BRing中Kr束发生横向模耦合不稳定性的流强阈值从2.7x1011 ppp提升到4.4x1011ppp.