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
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。
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.
分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2024-04-26
摘要： 高能宇宙辐射探测设施（HERD）是计划部署在中国空间站上的旗舰级科学装置，旨在间接探测暗物质、精确测量宇宙线成分以及进行高能伽马射线的巡天观测。其中，硅电荷探测器是HERD的关键组成部分之一，用于测量从氢到镍的宇宙射线的电荷。为了对硅电荷探测器的电荷测量能力进行验证和分析，设计了硅电荷探测器束流样机的地检系统。该系统采用了Xilinx公司的ZYNQ UltraScale+ MPSoC芯片作为控制芯片，并实现了LVDS数据接收、编解码、RS-422控制和千兆以太网数据接收存储功能。硅电荷探测器束流样机参加了欧洲核子中心的重核束流实验，地检系统在束流实验采集了100G实验数据,功能稳定可靠为HERD项目硅电荷探测器的后续实验提供了重要的技术支持和数据基础。
分类： 核科学技术 >> 同位素技术 提交时间： 2024-04-26
摘要： We proposed and compared three methods (filter burnup, single-energy burnup, and burnup extremum analysis) to build a high-resolution neutronics model for 238Pu production in high-flux reactors. The filter burnup and single-energy burnup methods have no theoretical approximation and can achieve a spectrum resolution of up to ~1 eV, thereby constructing the importance curve and yield curve of the full energy range. The burnup extreme analysis method combines the importance and yield curves to consider the influence of irradiation time on production efficiency, thereby constructing extreme curves. The three curves, which quantify the transmutation rate of the nuclei in each energy region, are of physical significance because they have similar distributions. A high-resolution neutronics model for 238Pu production was established based on these three curves, and its universality and feasibility were proven. The neutronics model can guide the neutron spectrum optimization and improve the yield of 238Pu by up to 18.81%. The neutronics model revealed the law of nuclei transmutation in all energy regions with high spectrum resolution, thus providing theoretical support for high-flux reactor design and irradiation production of 238Pu
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.
分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2024-04-20
摘要： 经过几十年的研究，对现有反应堆合金材料服役工况下的腐蚀问题及规律已经有了较为清晰的认识，但是依然存在一些待解决的问题，如反应堆合金材料腐蚀中本质过程的理解，单一因素在腐蚀过程中所起的作用，新材料以及极端环境下的腐蚀行为预测等。基于量子力学的密度泛函理论计算可以精确地预测极短时间内原子的运动过程以及相关能量的变化，近年来逐渐成为反应堆合金材料腐蚀过程研究的重要辅助手段，这将有助于解决上述问题。本文首先介绍了密度泛函理论方法，主要包括理论基础、发展过程与主流计算软件。之后，综述了密度泛函理论在反应堆合金材料腐蚀领域应用的研究现状，包括水冷堆、液态金属冷却堆、熔盐堆介质环境中反应堆合金材料表面的吸附、解离、结合、内部扩散等腐蚀行为。
分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2024-04-19
摘要： 为满足高能物理实验对基本粒子检测和分析的需求，现代像素探测器研发日益趋向追求低功耗、高分辨率、高读出效率的性能要求。本文研究了一款名为IMPix-N1的硅像素探测器数模混合读出芯片，像素阵列由16行×16列像素单元构成，每个像素单元面积为100μm×100μm，像素阵列部分以1行×8列的像素单元为一个超级像素，其具有共同的逻辑电路进行控制。芯片具有像素配置模式和三种像素地址读出方式的工作模式，实现了对击中粒子时间、能量及位置信息的测量、存储及读出。时间数字转换电路（TDC）可以同时测量和记录粒子的到达时间 TOA 和过阈时间 TOT，时间测量精度为5ns。IMPix-N1适用于要求高时间、空间分辨率以及快速数据获取能力的粒子探测实验。在TSMC 180 nm工艺下，芯片整体使用digital-on-top的方法进行设计。本设计对像素单元数字电路、超级像素控制电路和外围数字电路进行仿真验证，前后仿真结果一致，满足设计要求。
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2024-04-19
Lu, Yudong
Zheng, Jinxing
Liu, Xufeng
Wu, Huan
Ge, Jian
Xu, Kun
Li, Ming
Liu, Haiyang
Zhu, Lei
Liu, Fei
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.
分类： 核科学技术 >> 核科学与技术 提交时间： 2024-04-15
摘要： 活化-燃耗计算是反应堆分析的重要组成部分，需要耦合临界输运程序和点燃耗程序来迭代求解。LightAB（Light Activation and Burnup）是一个新的轻量化的通用活化-燃耗分析程序，可以用来处理活化-燃耗系统。LightAB采用了基于燃耗计算程序ORIGEN-2和ORIGEN-S的燃耗数据库，采用了处理刚性燃耗系统的切比雪夫有理逼近算法（Chebyshev rational approximation method, CRAM）。LightAB支持在衰变模式，定通量模式和定功率模式下的活化-燃耗计算。为了验证LightAB程序的正确性，计算237Np衰变问题和锆（Zr）合金的固定通量辐照问题，与燃耗程序ORIGEN-2.1程序的结果一致。实现了LightAB和RMC程序的耦合并用于计算加压水慢化冷却反应堆压水堆（Pressurized Water Reactor, PWR）栅元燃耗基准题、PWR组件燃耗问题、经合组织/核能机构（OECD/NEA）快堆燃耗基准问题，计算结果与RMC的燃耗计算模块一致。在超钚同位素的辐照生产与RMC对比模拟计算中LightAB展现出良好的应用前景。
分类： 核科学技术 >> 核科学与技术 提交时间： 2024-04-15
摘要： 天环一号（CAT-1: China Astro-Torus 1）是一个悬浮偶极场磁约束装置，主要用于偶极场等离子体物理实验研究，要求中心悬浮超导磁体在无冷却和无电源条件下稳定悬浮至少5h。本文设计了超导托举磁体与中心悬浮磁体环耦合的悬浮控制系统，为确保1200 kg、5 MA中心悬浮磁体环稳定悬浮，完成了控制系统的Simulink模型建立和仿真，基于 Routh-Hurwitz稳定判据，研究了PID（Proportion-Integral-Derivative）控制策略对稳定控制影响，确定了稳定控制参数选取的范围：理想条件下PD（Proportion-Derivative）控制系统上升时间为0.1545 s、峰值时间为0.6283 s、调节时间0.0848 s。结果表明：基于PID能够在较短的时间内将悬浮超导环恢复在预设平衡位置，采用合适的启动方式可极大的降低电路的负载。本结果为悬浮超导悬浮偶极场装置设计研发提供关键技术支撑。
分类： 核科学技术 >> 核科学与技术 提交时间： 2024-04-14
摘要： 不确定度量化已经成为反应堆物理分析的普遍需求，核数据的协方差数据是开展不确定度量化的基础数据。在核数据处理程序NECP-Atlas中开发了协方差数据产生模块covar_calc，产生适用于蒙特卡罗程序的连续能量协方差数据库与确定论程序的多群协方差数据库。covar_calc可根据不同核数据在评价核数据库中的存储格式及不同的计算方法，分别处理评价核数据库给出的所有协方差数据，包括：平均裂变中子数、截面、次级粒子角度分布、裂变谱、共振参数、中子活化截面等数据的协方差数据。通过与核数据处理程序NJOY21中协方差数据制作模块的对比验证，表明NECP-Atlas制作的多群协方差数据库的精度与NJOY21相当,最大偏差小于0.1%。在此基础上使用蒙特卡罗计算程序NECP-MCX和不确定度量化程序NECP-UNICORN分别计算得到不同基准题的灵敏度系数，并分别结合连续能量协方差数据库和多群协方差数据库，利用“三明治公式”计算得到最终的不确定度。结果表明，基于NECP-Atlas制作的多群协方差数据库计算得到的不确定度具有与NJOY21相当的精度。连续能量协方差和多群协方差制作精确，满足蒙特卡罗程序和确定论程序使用需求。
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.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2024-04-11
Xian-Lin Yang
Chang-Lin Lan
Yu-Ting Wei
Yi Zhang
Gong Jiang
Bo Xie
Yu Liu
Hong-Tao Shen
Xiao-Jun Sun
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.
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。
分类： 核科学技术 >> 核科学与技术 提交时间： 2024-04-09
摘要： 特征线方法（Method of Characteristics，MOC）因其具备强大的几何处理能力，且在计算过程中亦能兼顾计算成本和计算精度，被广泛应用于高保真数值模拟计算中。常见的输运计算方法除MOC外，还包括碰撞概率法（Collision Probability Method，CP）和界面流法（Interface Current Method，IC）等。本文从方法理论以及数值计算上将MOC、CP和IC进行比较分析，对于评估其在pin-by-pin计算中的能力尤为重要。同时在MOC计算中，不同的参数选择会对计算成本和计算精度产生影响，因此有必要进行敏感性分析以寻求最佳参数。本文首先将三种计算方法从原理上进行比较分析，再基于2D C5G7-MOX基准题完成了数值计算及MOC参数敏感性初步分析。计算结果表明：MOC在计算精度、计算效率和内存开销上均优于CP和IC。MOC的计算耗时和内存开销分别为23.9min和37.5MB，与参考解的相对误差仅为6.04×10-4。而CP和IC的计算耗时分别为MOC的56.7倍和15.6倍，内存开销分别为MOC的407.7倍和32.8倍。进一步通过参数敏感性分析发现：网格划分对计算内存开销以及计算时间的影响最大，极角的选择对计算精度的影响最大，并且给出一组建议参数：网格划分6×6，极角为GAUS且数目为2，方位角个数为30。该组参数的计算耗时为45.4min，内存开销为264.7MB，相对误差为5.9×10-5，归一化后的栅元均方根误差为0.00255。
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。
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。
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.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2024-04-08
摘要： In the framework of the Lanzhou Quantum Molecular Dynamics (LQMD) model, a possible probe to the neutron-skin thickness (δnp) of neutron-rich 48Ca is studied in 140A MeV 48Ca + 9Be projectile fragmentation reaction based on parallel momentum distribution (p//) of residual fragments.The Fermi-type density distribution is employed to initiate the neutron density distributions in the LQMD simulation. A combined Gaussian function with different width parameters for the left side (ΓL) and the right side (ΓR) in distribution are used to describe the p// of residual fragments. The value of ΓL, taking neutron-rich sulfur isotopes as examples, shows a sensitive correlation to δnp of 48Ca, which is suggested to be a probe to determine the neutron-skin thickness of the projectile nucleus.
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