分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2023-09-14
Liu, Tao
Song, Haisheng
Yu, Yuhong
Yan, Duo
Sun, Zhiyu
Tang, Shuwen
Lu, Fenhua
Wang, Shitao
Zhang, Xueheng
Li, Xianqin
Yang, Haibo
Fang, Fang
Zhang, Yongjie
Ma, Shaobo
Ong, Hooijin
Zhao, Chengxin
摘要：A fully digital data acquisition system based on a field-programmable gate array (FPGA) was developed for a CsI(Tl) array at the External Target Facility (ETF)in the Heavy Ion Research Facility in Lanzhou(HIRFL). To process the CsI(Tl) signals generated by γ-rays and light-charged ions, a scheme for digital pulse processing algorithms is proposed. Every step in the algorithms was benchmarked using standard γ and α sources. The scheme, which included a moving average filter, baseline restoration, leading-edge discrimination, moving window deconvolution and digital charge comparison was subsequently implemented on the FPGA. A good energy resolution of 5.7% for 1.33 MeV γ rays and excellent α-γ identification using the digital charge comparison method were achieved, which satisfies CsI(Tl) array performance requirements.
分类： 核科学技术 >> 核仪器、仪表 提交时间： 2023-09-06
摘要：上海光源BL02U2线站已经安装了两台德国HUBER公司的衍射仪，为了进一步满足用户对掠入射衍射实验方法的需求，在两台衍射仪之间安装了一台新的掠入射衍射仪。本文介绍了掠入射衍射仪的整体方案，并针对高精度重载大行程位移台、探测器三维调节平台、样品台系统、控制系统等重要模块进行了详细的论述。实现了三台衍射仪的兼容运行，并以MoS2样品为例介绍了掠入射衍射仪的典型实验结果。目前该掠入射衍射仪已经稳定运行超过2年，完善了上海光源的掠入射衍射实验条件，为材料表面科学研究提供了更丰富的实验平台。
分类： 核科学技术 >> 核科学与技术 提交时间： 2023-09-06
摘要：The accurate modeling of depletion, intricately tied to the solution of the neutron transport equation, is crucial for the design, analysis, and licensing of nuclear reactors and their fuel cycles. This paper introduces a novel multi-group Monte-Carlo depletion calculation approach. Multi-group cross-sections (MGXS) are derived from both 3D whole-core modeling and a 2D fuel subassembly using the continuous-energy Monte-Carlo technique. Core calculations employ the multi-group Monte-Carlo method, accommodating both homogeneous and specific local heterogeneous geometries. The proposed method has been validated against the MET-1000 metal-fueled fast reactors, using both the OECD/NEA benchmark and a new refueling benchmark introduced in this paper. Our findings suggest that microscopic MGXS, produced via the Monte-Carlo technique, are viable for fast reactor depletion analyses. Furthermore, the locally heterogeneous model with angular-dependent MGXS offers robust predictions for core reactivity, control rod value, sodium void value, Doppler constants, power distribution, and concentration levels.
分类： 核科学技术 >> 核科学与技术 提交时间： 2023-08-27
摘要：As a unique probe, precision measurement of textit{pp} solar neutrinos is important for studying the Sun's energy mechanism, monitoring thermodynamic equilibrium, and studying neutrino oscillation in the vacuum-dominated region. For a large-scale liquid scintillator detector, one bottleneck for textit{pp} solar neutrino detection comes from pile-up events of intrinsic $^{14}$C decays. This paper presents a few approaches to discriminate textit{pp} solar neutrinos and $^{14}$C pile-up events by considering the difference in their time and spatial distributions. In this work, a Geant4-based Monte Carlo simulation is constructed. Then multivariate analysis and deep learning technology were adopted respectively to investigate the capability of $^{14}$C pile-up reduction. As a result, the BDTG model and VGG network showed good performance in discriminating textit{pp} solar neutrinos and $^{14}$C double pile-up events. hl{At the $^{14}$C concentration assumption $5 times10^{-18} g/g$,} their signal significance can achieve 10.3 and 15.6 using only one day of statistics. In this case, the signal efficiency is 51.1 % for discrimination using the BDTG model when rejecting 99.18 % $^{14}$C double pile-up events, and the signal efficiency is 42.7 % for the case using the VGG network when rejecting 99.81 % $^{14}$C double pile-up events.
分类： 核科学技术 >> 核科学与技术 提交时间： 2023-08-27
摘要：Intensity-modulated particle therapy (IMPT) with carbon ions is comparatively susceptible to various uncertainties caused by breathing motion, including range, setup, and target positioning uncertainties. To determine relative biological effectiveness-weighted dose (RWD) distributions that are resilient to these uncertainties, the reference phase-based four-dimensional (4D) robust optimization (RP-4DRO) and each phase-based 4D robust optimization (EP-4DRO) method in carbon-ion IMPT treatment planning were evaluated and compared. Based on RWD distributions, 4DRO methods were compared with 4D conventional optimization using planning target volume (PTV) margins (PTV-based optimization) to assess the effectiveness of the robust optimization methods. Carbon-ion IMPT treatment planning was conducted in a cohort of five lung cancer patients. The results indicated that the EP-4DRO method provided better robustness (P=0.080) and improved plan quality (P=0.225) for the clinical target volume (CTV) in the individual respiratory phase when compared with the PTV-based optimization. Compared with the PTV-based optimization, the RP-4DRO method ensured the robustness (P = 0.022) of the dose distributions in the reference breathing phase, albeit with a slight sacrifice of the target coverage (P=0.450). Both 4DRO methods successfully maintained the doses delivered to the organs at risk (OARs) below tolerable levels, which were lower than the doses in the PTV-based optimization (P<0.05). Furthermore, the RP-4DRO method exhibited significantly superior performance when compared with the EP-4DRO method in enhancing overall OAR sparing in either the individual respiratory phase or reference respiratory phase (P<0.05). In general, both 4DRO methods outperformed the PTV-based optimization in terms of OAR sparing and robustness.
分类： 核科学技术 >> 粒子加速器 提交时间： 2023-08-21
摘要：The purpose of this study was to design a rapid cycling synchrotron, making it capable of proton beam ultra-high dose rate irradiation, inspired by laser accelerators. The design had to be cheap and simple. We consider our design from six aspects: the lattice, injection, extraction, space charge effects, eddy current effects and energy switching. Efficiency and particle quantity must be addressed when injected. The space charge effects at the injection could affect particles’ number. The eddy current effects in the vacuum chambers would affect the magnetic field itself and generate heat, all of which need to be taken into account. Fast extraction can obtain 1010 protons/pulse, equal to instantaneous dose rate up to 107 Gy/s in a very short time, while changing various extraction energies rapidly and easily to various deposition depths. In the further research we expect to combine a delivery system with this accelerator to realize the FLASH irradiation.
分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2023-08-14
摘要：Alloys of uranium and molybdenum are considered as the future of nuclear fuel and defense materials. However, surface corrosion is a fundamental problem in practical applications and storage. In this study, the static and dynamic evolution of carbon monoxide (CO) adsorption and dissociation on γ-U (1 0 0) surface with different Mo doping levels was investigated based on density functional theory and ab initio molecular dynamics. During the static calculation phase, parameters, such as adsorption energy, configuration, and Bader charge, were evaluated at all adsorption sites. Furthermore, the time-dependent behavior of CO molecule adsorption were investigated at the most favorable sites. The minimum energy paths for CO molecular dissociation and atom migration were investigated using the transition state search method. The results demonstrated that the CO on the uranium surface mainly manifests as chemical adsorption before dissociation of the CO molecule. The CO molecule exhibited a tendency to rotate and tilt upright adsorption. However, it is difficult for CO adsorption on the surface in one of the configurations with CO molecule in vertical direction but oxygen (O) is closer to the surface. Bader charge illustrates that the charge transfers from slab atoms to the 2π* antibonding orbital of CO molecule and particularly occurs in carbon (C) atoms. The time is less than 100 fs for the adsorptions that forms embryos with tilt upright in dynamics evolution. The density of states elucidates that the overlapping hybridization of C and O 2p orbitals is mainly formed via the d orbitals of uranium and molybdenum (Mo) atoms in the dissociation and re-adsorption of CO molecule. In conclusion, Mo-doping of the surface can decelerate the adsorption and dissociation of CO molecules. A Mo-doped surface, created through ion injection, enhanced the resistance to uranium-induced surface corrosion.
分类： 核科学技术 >> 核科学与技术 提交时间： 2023-08-08
摘要：摘要：将中国原子能科学研究院研制的核电厂乏燃料水池格架硼铝合金中子吸收材料检测设备进行升级改进，研发了集成数据获取系统、传动系统和控制记录分析系统。该检测设备可适用于不同尺寸的样板的多点测量，具有连续、快速、全面积检测的特点，具有定点式检测和移动式检测两种模式。完成了20cm×30cm的悬挂样片、373cm×19.5cm的长板、6cm×6cm的方形样板和Φ5cm×0.3cm的圆形样板的检测工作，并且对检测结果进行分析。该硼铝合金材料中子吸收性能检测设备为开展国产含硼中子吸收材料的无损检测研究奠定了基础，为核电厂乏燃料水池的临界安全监测提供了有力保障。
分类： 核科学技术 >> 核安全 提交时间： 2023-08-07
摘要：传统静态可靠性评估方法难以表征核电厂数字化控制系统的动态交互性和时间依赖性。为了解决这一问题，以数字化主给水控制系统（DMFCS）为研究对象，提出了一种基于动态故障树（DFT）和动态贝叶斯网络（DBN）的动态可靠性评估方法，对DMFCS进行动态可靠性评估。首先，应用DFT方法，建立了表征DMFCS动态交互性的DFT模型；然后，应用DFT至DBN的转换策略，建立了表征DMFCS时间依赖性的DBN模型；最后，通过DBN正向推理计算得到了DMFCS随时间变化的可靠度曲线，逆向推理计算得到了根节点的后验概率，重要度分析识别了系统薄弱环节。结果表明：所提方法能够很好地描述DMFCS的动态交互性和时间依赖性，分析结果为系统智能维护、日常检修提供了科学依据，进一步提高了DMFCS可靠性和安全性。
分类： 核科学技术 >> 粒子加速器 提交时间： 2023-07-08
摘要：Radio-frequency (RF) breakdown analysis and location are critical for successful development of high-gradient traveling-wave (TW) accelerators, especially those expected to generate high-intensity, high-power beams. Compared with commonly used schemes involving dedicated devices or complicated techniques, a convenient approach for breakdown locating based on transmission line (TL) theory offers advantages in the typical constant-gradient TW-accelerating structure. To deliver such an approach, an equivalent TL model has been constructed to equate the TW-accelerating structure based on the fundamental theory of the TL transient response in the time domain. An equivalence relationship between the TW-accelerating structure and the TL model has been established via analytical derivations associated with grid charts and verified by TL circuit simulations. Furthermore, to validate the proposed fault-locating method in practical applications, an elaborate analysis via such a method has been conducted for the recoverable RF-breakdown phenomena observed at an existing prototype of a TW-accelerating-structure-based beam injector constructed at the Huazhong University of Science and Technology. In addition, further considerations and discussion for extending the applications of the proposed method have been given. This breakdown-locating approach involving the transient response in the framework of TL theory can be a conceivable supplement to existing methods, facilitating solution to construction problems at an affordable cost.
分类： 核科学技术 >> 辐射防护技术 提交时间： 2023-07-07
摘要：Environmental radon emanates from the exhalation and release of soil, rocks, and building materials. Environmental radon contamination tracing and radon pollution prevention and control require the measurement of the radon exhalation rate on media surfaces. Reliable measurements of the radon exhalation rate cannot be achieved without regular calibration of the measuring instrument with a high-performance reference device. In this study, a reference device for the calibration of radon exhalation rate measuring instruments was developed using a diffusion solid radon source with a high and stable radon emanation coefficient, an integrated diffusion component composed of a plasterboard and a high-density wooden board, an air pressure balance device, a radon accumulation chamber, and a support structure. The uniformity and stability of the reference device were evaluated using the activated carbon-γ spectrum and open-loop method, respectively, to measure the radon exhalation rate. The reference device achieved different radon exhalation rates by using different activities of diffusion solid radon sources. Nineteen measurement points were regularly selected on the radon exhalation surface of the reference device, and the uniformity of the radon exhalation rate exceeded 5%. The short-term stability of the reference device was better than 5% under different environmental conditions and was almost unaffected by the ambient air pressure, environmental temperature, and relative humidity.
分类： 核科学技术 >> 核动力工程技术 提交时间： 2023-07-04
摘要：为研究压水堆严重事故一体化分析程序开发规范，为严重事故一体化分析程序开发提供必要的参考。本文基于当前国内相关法规要求和规范、软件开发法规标准体系、核安全分析与设计软件开发规范及要求、核安全分析及设计软件评价要求，研究了压水堆严重事故一体化分析程序开发过程中相关规范体系，在此基础上，对比和建议了严重事故程序开发的标准体系，以及质量保证、验证与确认的规范，初步建立了严重事故程序开发的标准体系要求。在已有的和正在开展的核动力厂安全分析软开发与件评价工作的基础上，初步建立了严重事故程序开发的标准体系，对压水堆严重事故一体化分析程序开发规范做了初步的建议。并在已有程序评价的实践基础上，讨论了严重事故程序的评价要求及其中各方面的重点。
分类： 核科学技术 >> 粒子加速器 提交时间： 2023-06-25
摘要：在这项研究中，开发了一种用于医学放疗的x波段驻波双周期线性加速器，它可以使用2.4 MW速调管将电子加速到9 MeV。该结构工作在π/2模式下，采用腔间磁耦合，产生适当的相邻模分离，频率为10 MHz。加速器长度小于600mm，由4个束状细胞和29个正常细胞组成。进行了几何优化、全尺寸射频(RF)模拟和波束动力学计算。利用低功率射频测试对加速器进行了制造和检测。冷态试验结果与仿真和实际测量结果吻合较好。在高功率射频测试中，测量了输出束流、能谱、俘获比和加速器出口光斑大小。输入功率为2.4 MW，脉冲电流为100 mA，输出光斑均方根半径约为0.5 mm。输出动能为9.04 MeV，谱频宽为3.5%，表明该加速器具有良好的性能。
分类： 核科学技术 >> 核科学与技术 分类： 物理学 >> 核物理学 提交时间： 2023-06-24
摘要：利用CR-39探测器、HSP-1000高速成像显微镜和PitFit径迹分析软件研究了中高能28Si与C靶反应产生的弹核碎片角分布。通过束流照射、化学蚀刻以及径迹重建等实验过程，给出了能量为736 AMeV 28Si与C靶反应弹核碎片发射角分布的最新实验结果，并与能量在800 AMeV和775 AMeV下28Si与C靶反应产生的弹核碎片发射角分布进行比较。结果表明，弹核碎片发射角的角分布平均值和宽度大于28Si束流粒子的散射角；大多数弹核碎片发射角小于2.0度，很少有发射角大于2.0度；不同电荷数Z的弹核碎片发射角平均值范围在1.0度以内，其角分布平均值和宽度随碎片电荷数Z的增加总体呈现减小的趋势。
分类： 核科学技术 >> 核科学与技术 提交时间： 2023-06-21
摘要：熔盐堆作为第四代先进反应堆的重要堆型之一，以高沸点熔盐为核燃料，具有高温输出、常压操作等特点。而基于温差发电的热管熔盐堆，兼具了熔盐堆、热管和温差发电的优势，具有输出温度高、热电转换效率高、结构简单及安全可靠等优点。故该堆型在能源系统领域具有极大的优势，是外太空及深海探测任务的理想能源。但因堆芯熔盐低热导率而形成的热管密集排布给热管冷凝段温差发电传热设计带来了难题。针对该堆型设计需求，本文提出适于熔盐堆的热管-温差发电耦合系统结构并进行了传热分析。堆芯热管冷凝段采用塔式温差发电系统结构设计，整体热端座与堆芯热管冷凝端相配合，形成从下至上的第1层至第N层热段套；冷端座套设于热端座外，内设冷端热管通道；热端座的外侧壁与冷端座的内侧壁之间贴有温差发电片，发电片间隙采用保温棉减少漏热。采用Ansys Workbench开展了适于热管熔盐堆的四层塔式温差发电系统传热仿真模拟，分析表明，系统运行时，整体塔座温度分布均匀，热量有效利用率大于 96%，系统漏热量小于4%，发电片两侧温差大于490℃，利于提高热电转换效率，设计具有可行性，有利于推动温差发电在热管熔盐堆中的应用。
分类： 物理学 >> 核物理学 分类： 核科学技术 >> 乏燃料后处理技术 提交时间： 2023-06-20 合作期刊: 《原子核物理评论》
摘要：第一性原理被应用在核工程领域关注的热中子散射材料的热中子截面计算中，本文以Al和Bi金属的热中子截面制作为例，分别基于第一性原理冷冻声子法和密度泛函微扰法，采用VASP结合PHONONY程序计算了它们的声子色散关系和声子态密度，基于NJOY程序，在LEAPR中添加Bi相干散射处理，制作了Al和Bi的热中子散射截面库，结果表明：对于Al，相较于冷冻声子法，密度泛函微扰理论的声子态密度得到的热中子散射截面与ENDF8.0符合更好，对于Bi，采用密度泛函微扰法消除了冷冻声子法的虚频现象，得到的热中子散射结果与实验值符合较好。本文从探索材料内部特征机理的角度提出了一种更基础、更有预见性的制作热中子截面的方法，为研究新型反应堆的核材料热化机理奠定了理论基础。
分类： 核科学技术 >> 核科学与技术 分类： 核科学技术 >> 粒子加速器 提交时间： 2023-06-20
摘要：With the development of high-performance photon sources which have extremely low emittance,
autotuning magnet girders have drawn more and more attention, especially for diffraction-limited storage
rings and free-electron lasers. The biggest challenge is to simultaneously obtain high stability and high
flexibility. In this paper, an autotuning magnet-girder prototype has been designed and developed.
Topological optimization, multipoint supports, and locking systems have been applied for magnet-girder
design to improve the stability. The modal analysis accords with the vibration test well. The natural
frequency of the magnet-girder assembly is deduced as high as 45.6 Hz, which demonstrates good stability.
Ball-cam movers have been chosen as adjustment mechanisms, and a closed-loop control scheme has been
used to pursue high accuracy. The kinematic resolution is better than 1 μm, and the accuracy is better than
1 μm within the adjusting range of #1;5 mm. Besides, it can eliminate most of the calibration, which can
save much manpower and time. The tests demonstrate that the magnet girder can be used for beam-based
girder alignment with high stability and high accuracy.
分类： 核科学技术 >> 裂变堆工程技术 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要：Molecular dynamics method is used to investigate the displacement cascades in Ni-Mo binary alloy. Effects of the irradiation temperature, energy of the primary knock-on atoms and concentration of solute Mo atoms are taken into consideration on radiation damage to the Ni-Mo alloy. It is found that Mo atoms reduce production of the Frenkel pairs at 100 K, while they enhance defect production at 300 K and 600 K. Size of the largest defect clusters decreases with increasing concentrations of Mo atoms (CMo) at 100 K, but it increases with CMo at 300 K and 600 K. Most of the point defects get clustered in cascades leaving only a few vacancies and interstitials isolated.
分类： 核科学技术 >> 裂变堆工程技术 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要：To investigate the corrosion products of Cr in molten FLiNaK salt (46.5 mol% LiF–11.5 mol% NaF–42 mol% KF), the corrosion test of the pure metal Cr was performed in molten FLiNaK salt at 700 ℃ for 200 h. The FLiNaK salt after the corrosion test was thoroughly investigated by X-ray absorption near-edge structure spectroscopy, a transmission electron microscope, and X-ray diffraction. The results demonstrate that the predominant oxidation state of Cr in FLiNaK salt is Cr3+, and the main corrosion product in cooled FLiNaK salt is K2NaCrF6.
分类： 核科学技术 >> 裂变堆工程技术 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要：Based on the design of CLEAR (China LEAd-based Reactor), it is important to study the molten LBE (Lead-Bismuth Eutectic)/water interaction following an incidental steam generator tube rupture (SGTR) accident. Experiments were carried out to investigate the fragmentation behavior of the molten LBE/water contacting interface, with a high-speed video camera to record the fragmentation behavior of 300–600 ℃ LBE at 20 ℃ and 80 ℃ of water temperature. Violent explosion phenomenon occurred at water temperature of 20 ℃, while no explosion occurred at 80 ℃. Shapes of the LBE debris became round at 80 ℃ of water temperature, whereas the debris was of the needle-like shape at 20 ℃. For all the molten LBE and water temperatures in the present study, the debris sized at 2.8–5.0 mm had the largest mass fraction. The results indicate that the dominant physical mechanism of the molten LBE fragmentation was the Kelvin-Helmholtz instability between LBE/water direct contact interface.
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