分类： 核科学技术 >> 核科学技术其他学科 提交时间： 2024-04-29
摘要： 随钻中子孔隙度测量通过测量热中子计数，评价地层减速长度从而获得地层孔隙度，是一种地层储集性评价的重要方法，被广泛应用在复杂油气田的勘探开发中。随钻D-T源中子孔隙度测井仪器由脉冲中子源和多探测器组成，随钻可控源中子孔隙度响应规律受仪器钻铤结构及仪器测量方式的影响，同时井眼参数、流体类型和地层等因素影响仪器周围的中子场分布及测井响应规律。本文利用蒙特卡罗模拟方法，研究不同钻铤结构及仪器设计、仪器测量环境因素和地层参数对随钻D-T源中子孔隙度测量过程中子通量分布与孔隙度响应规律的影响。仪器钻铤结构与测量环境影响分析结果表明，仪器采用侧开槽设计时探测器计数变大，但地层孔隙灵敏度仅为导流通道环绕设计的0.36倍，并明确钻铤尺寸是测量环境影响的主控因素。地层岩性、泥质含量和地层水矿化度的地层环境因素影响分析结果显示，岩性作为地层属性在不同孔隙度下的影响几乎为常量，泥质含量的影响程度在低孔条件下是地层水矿化度影响程度的2.9倍，高孔隙度下为1.48倍，因此地层泥质含量为地层环境影响的主控因素。
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.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2024-04-29
Gao-Long Zhang
Zhen-Wei Jiao
Guang-Xin Zhang
E. N. Cardozo
D. Bazzacco
D. R. Napoli
F. Galtarossa
F. Recchia
A. Illana
S. Bakes
I. Zanon
S. Aydin
G. de Angelis
M. Siciliano
H. Q. Zhang
B. Paes
S. P. Hu
J. Q. Qian
Daniele Mengoni
W. W. Qu
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.
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.
分类： 核科学技术 >> 核科学与技术 提交时间： 2024-04-29
摘要： 为推动“一带一路”共建国家能源合作需求多元化发展，解决新丝绸之路经济带沿线上安全、高效的能源供应需求，提出了固有安全一体化小型氟盐冷却高温堆FuSTAR设计方案。为验证FuSTAR反应堆自身负荷跟踪运行的能力以及其安全性，对FuSTAR系统进行了详细的热工水力和控制系统的建模计算，并深入分析了其抗干扰特性和负荷运行跟踪能力。在不依赖外部控制系统的情况下，小型氟盐冷却高温堆FuSTAR展现出了一定的负荷跟踪能力，这主要归功于其具有固有安全特性，使得反应堆能够在负荷变化下实现自我稳定与调节。在采用冷却剂出口温度恒定控制方案后，FuSTAR的核反应堆负荷跟踪能力得到了进一步增强，在10%FP负荷阶跃变化以及5%FP/min速率线性升降负荷的测试中，核反应堆功率的超调量均严格控制在5%以内，充分满足了反应堆安全运行的要求。
分类： 物理学 >> 核物理学 分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2024-04-28
摘要： A charged particle array, named MATE-PA, which serves as an auxiliary detec#2;tor system to the Multi-purpose Active-target Time projection chamber for nuclear astrophysical and exotic beam Experiments (MATE) has been con#2;structed. The array is composed of twenty single-sided strip-silicon detectors, covering around 10% of the solid angle. It is dedicated for the detection of reaction-induced charged particles which penetrate the MATE active volume. The performance of MATE-PA has been experimentally studied using an alpha source, and a 36-MeV 14N beam injected into the chamber of MATE, filled with a mixture gas of 95% 4He and 5% CO2 under the pressure of 500 mbar, at the Radioactive Ion Beam Line in Lanzhou (RIBLL). The results demonstrate good separation of light charged particles with the forward double-layer silicon detectors of MATE-PA. The energy resolution of the Si detectors was deduced to be about 1% (σ) for an energy loss of about 10 MeV by the α particles. The inclusion of MATE-PA helps improve particle identification, and increases the dynamic range for the kinetic energy of charged particles, in particular that of α particles up to about 15 MeV.
分类： 核科学技术 >> 裂变堆工程技术 提交时间： 2024-04-27
摘要： The heavy-water-moderated molten-salt reactor (HWMSR) is a newly proposed reactor concept, in which heavy water is adopted as the moderator and molten salt dissolved with fissile and fertile elements is used as the fuel. Issues arising from graphite in traditional molten-salt reactors, including the positive temperature coefficient and management of highly radioactive spent graphite waste, can be addressed using the HWMSR. Until now, research on the HWMSR has been centered on the core design and nuclear-fuel cycle to explore the viability of the HWMSR and its advantages in fuel utilization. However, the core safety of the HWMSR has not been extensively studied. Therefore, we evaluate typical accidents in a small modular HWMSR, including fuel-salt inlet temperature-overcooling and -overheating accidents, fuel-salt inlet flow-rate decrease, heavy-water inlet temperature-overcooling accidents, and heavy-water inlet mass flow-rate decrease accidents, based on a neutronics and thermal-hydraulics coupled code. The results demonstrated that the core maintained safety during the investigated accidents.
分类： 核科学技术 >> 放射性计量学 提交时间： 2024-04-26
摘要： The aim of this study is to evaluate the uncertainty of 2πα and 2πβ surface emission rates using the windowless multiwire proportional counter method. This study used the Monte Carlo method (MCM) to validate the conventional Guide to the Expression of Uncertainty in Measurement (GUM) method. A dead-time measurement model for the two-source method was established based on the characteristics of a single-channel measurement system, and the voltage threshold correction factor measurement function was indirectly obtained by fitting the threshold correction curve. The uncertainty in the surface emission rate was calculated using the GUM method and the law of propagation of uncertainty. The MCM provided clear definitions for each input quantity and its uncertainty distribution, and the simulation training was realized with a complete and complex mathematical model. The results of the surface emission rate uncertainty evaluation for four radioactive plane sources using both methods showed an uncertainty consistency En < 0.070 for the comparison of each source, and the uncertainty results of the GUM were all lower than those of the MCM. However, the MCM has a more objective evaluation process and can serve as a validation tool for GUM results.
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 >> 粒子加速器 提交时间： 2024-04-25
摘要： 摘要：目的：放疗过程中的锥形束CT(cone beam CT，CBCT)可为患者提供更精确的靶区定位，但由于散射线多造成的对比度低、噪声大、伪影大等，导致影像质量较差，在实时放疗中无法用于剂量计算。本研究旨在使用Unet、CyclaGAN和CGAN等三种深度学习网络生成基于CBCT的合成CT(sCTs)，研究并对比三种sCTs的图像质量。方法：使用78例前列腺癌患者的CBCT和计划CT(pCTs)数据，进行预处理后，其中63例为训练集，10例为测试集，5例为验证集，分别训练和评估基于三种模型的图像质量。使用平均绝对误差(MAE)、平均误差(ME)、均方误差(MSE)、峰值信噪比(PSNR)、结构相似性(SSIM)和空间非均匀性(SNU)等影像评估指标以及频域信息进行评估。结果：在三种模型中，cGAN模型在各个指标上都表现出最优的性能。在全局条件下的图像质量方面，平均MAE降低到7.77HU, MSE降低到4.99，PSNR提高到54.95，SSIM提高到96%。结论：应用深度学习方法可以大幅修正CBCT的HU值并生成对应高质量的sCT，针对前列腺癌的病人，CGAN模型生成的sCT拥有更好的影像质量，使用该模型生成基于CBCT的sCT可以为前列腺癌放疗靶区剂量计算提供。
分类： 核科学技术 >> 粒子加速器 提交时间： 2024-04-25
摘要： HVE-400注入机是专用的低能加速器离子注入设备，主要用于半导体材料的硼磷参杂工艺。注入机的离子源及引出偏转系统处于高电位，而相应控制系统处于地电位，控制信号与高压端各参数的测量反馈信号需要在地电位与高电位之间通过光纤进行传输，以隔离高压。因光纤传输控制与监测系统年久老化不能稳定工作而进行升级改造。改造采用无线数字传输模式取代多路光纤传输，具有高压隔离功能；利用先进的分散集中控制方式代替原有的分散式单点控制方式，将所有的控制与监测功能集中到工控计算机上进行数字化操作与显示。计算机控制监测系统还设计了两种方式离子质量数软件计算功能。升级改造后，注入机高压平台控制与监测系统具有无线化、数字化、集中控制、操作简单方便等特点。
分类： 核科学技术 >> 核科学技术其他学科 提交时间： 2024-04-25
摘要： 复杂岩性井段对密度测井数据精度要求很高，传统的计算模型不能很好的满足此时的高精度要求。为此提出利用机器学习回归预测模型提高密度测井曲线的精度，考虑到XGBoost模型的过拟合问题，基于SSA算法改进XGBoost进而提出了SSA-XGBoost密度预测模型。采用蒙特卡罗模拟双探测器密度测井仪器，获取不同密度地层数据以验证该模型的预测效果。利用SSA算法优化SVR、RFR和LSTM参数，构建SSA-SVR、SSA-RFR和SSA-LSTM模型预测模拟地层密度，并使用量化评价指标和泰勒图模型对比分析各个模型的预测性能。此外，还分析了不同预测模型对实际密度测井数据的预测效果。结果表明SSA-XGBoost模型的预测精度高于传统脊-肋图模型，在实际密度测井数据处理中具有广阔的应用前景。
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 >> 核科学与技术 提交时间： 2024-04-24
摘要： 射频功率源是负离子源中性束注入电源系统的重要组成部分，它为射频离子源产生等离子体和维持稳定放电提供射频电流。根据设计指标提出了全固态功率放大器设计结构，并对射频通路环节的缓冲放大电路、预推动放大器、功率放大器、功率合成器、输出匹配和滤波进行了设计与分析。最后过实验实现了150kW的射频等离子体放电，验证了这一拓扑结构的可行性。
分类： 核科学技术 >> 核科学与技术 提交时间： 2024-04-24
摘要： 针对铅铋堆开展燃料组件子通道分析，对于铅铋堆的发展具有重要的意义。本研究的目的是修改和优化COBRA子通道程序，使其适用于铅铋反应堆，并验证其性能。修改包括调整物性参数、流换热模型、摩擦阻力模型以及湍流交混模型。然后将修改后的程序与实验数据和数值计算进行比较。针对宽参数质量流量条件，提出了一种与神经网络相结合的子通道优化方法。结果表明，改进后的子通道程序在实验工况下与实验结果和FLUENT结果吻合良好。分析了质量流量对计算精度的影响，指出神经网络可以提高计算精度。通过改进和神经网络优化子通道分析程序适用于宽参数质量流量工况下的铅铋堆子通道分析，可为铅铋堆的堆芯设计提供方法借鉴。
分类： 核科学技术 >> 核科学与技术 提交时间： 2024-04-22
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。
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