最新刊期
卷 44 ， 期 2 ， 2021
- “在受控核聚变领域，专家使用ORBIT代码，针对波纹扰动和NTM对托卡马克氘离子输运的影响进行了详细研究，为核聚变反应的维持提供了重要参考。”摘要：BackgroundTokamak is a possible implementation of controlled nuclear fusion whilst the particle transportation plays an important role in maintaining the progress of nuclear fusion reactions.PurposeThis study aims to investigate the effects of ripple field and neoclassical tearing mode (NTM) on the migration of deuterium ions in Tokamak by numerical simulation. and provide a reference for the confinement of high energy particles.MethodsThe guiding center orbit code ORBIT was employed for numerical simulation. Effects of NTM and ripple field on particles with different positions, pitch angles and energies, were studied in details.Results & ConclusionsSimulation results show that the particle loss rate is high under the condition of high magnetic surface and low pitch angle. NTM mainly causes the loss of passing particles, while the loss of trapped particles is mainly caused by ripple field. When both perturbations are considered, the loss of particles is approximately the sum of losses by two perturbations acting alone. Ripple field will significantly increase toroidal angular momentum diffusion of trapped particles without affecting the passing particles, whilst NTM mainly influences toroidal angular momentum diffusion of passing particles. The particle loss situation basically keeps the original characteristics regardless of NTM frequency varition, while the momentum diffusion condition of particle loss changes with the increase of NTM frequency.关键词：Ripple;Neoclassical tearing mode;ORBIT;Numerical simulation
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发布时间：2024-10-25 - “在β辐射伏特效应核电池仿真领域，专家基于Geant4框架建立了模拟β粒子能量沉积的通用模型，与Casino结果比较，验证了模型准确性。”摘要：BackgroundThe energy deposition behavior of β particles in transducer material is an important issue in the simulation of a betavoltaic battery, which is usually performed by Monte Carlo software Casino and MCNP (Monte Carlo N Particle Transport Code). However, it is difficult to simulate the continuous energy spectrum of β particles by Casino software. The commercial software MCNP is subject to many restrictions on its copyright, it is very necessary to study the energy deposition of β particles in transducer materials based on the universal open-source Monte Carlo program Geant4 (GEometry ANd Tracking, version 4).PurposeThis study aims to develop a model based on Geant4 to study the energy deposition of β particles in betavoltaic battery transducer materials.MethodsBased on the framework of Geant4 software, a general simulation model of energy deposition behavior was developed. The continuous β spectrum, the self-absorption of radioactive source, and the backscattering of β particles on the source-transducer interface were taken into account completely in this model for the Monte-Carlo simulation study, and the computation results were compared with that of Casino software.ResultsSimulation comparison results show that this simulation model can accurately simulate the energy deposition behavior of β particles in the transducer materials of betavoltaic battery.ConclusionsSimulation model proposed in this study can be used to study the energy deposition of β particles in the transducer materials with advantages of convenient application, open software and easy extension to other source-transducer combinations.关键词：GEANT4;63Ni;Betavoltaic battery;Energy deposition behavior
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发布时间：2024-10-25 - “在质子治疗机房屏蔽设计中，铁板嵌入深度对次级中子反射分布有显著影响。主屏蔽墙对次级中子反射贡献超95%，铁板嵌入深度增加可降低反射中子有效剂量率。”摘要：BackgroundThe protection of secondary neutrons in the complex secondary radiation of the 100~250 MeV proton therapy room has always been the focus of shielding design. Currently, iron plates embedded in concrete are often used to reduce neutron transmission, but this will cause significant neutron reflection (toward the patient). And neutrons have a high radiation weighting factor which may cause harmful effects on patients.PurposeThe study aims to investigate the reflection distribution of secondary neutrons in the proton therapy room and its impact on patients.MethodsFirst of all, a simple model of the proton therapy room was established, and Monte Carlo program FLUKA was used to calculate the effects of the secondary neutron reflection from different directions and at different embedding positions of the iron shield in the 245 MeV proton therapy room. Then, under the three irradiation modes of AP (Antero-posterior), PA (Posterior-anterior) and LAT (Lateral), the effective dose of the patient was calculated according to the energy of the reflected neutrons reaching the position of the patient whilst the neutron external radiation dose conversion coefficient given in report of ICPR (International Commission on Radiological Protection) Publication 116 was used.ResultsThe simulation results show that the main shielding wall contributes more than 95% to the reflection distribution of the secondary neutrons in the treatment room. The radiation dose level outside the treatment room is the lowest when the embedded depth of the iron plate in the wall is 0 (the iron plate is exposed in the room), but highest effective dose rates caused by reflected neutrons are 1.99 μSv‧s-1, 1.37 μSv‧s-1 and 1.00 μSv‧s-1, respectively, under the three irradiation modes of AP, PA and LAT. With the increase of embedding depth of iron plate, the effective dose rate of reflected neutron decreased gradually, but the decreasing trend becomes slower and slower.ConclusionsThe structure of the main shielding wall of the treatment room and the embedded position of the iron plate have a significant impact on the reflected secondary neutron energy spectrum and the patient's radiation health. This feature needs to be considered in the shielding design of the proton therapy room.关键词：Proton accelerator;Neutron protection;Monte Carlo
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发布时间：2024-10-25 - “在飞行时间型中子散射谱仪领域，中国散裂中子源专家对带宽限制中子斩波器性能进行了系统研究，验证了其满足工程需求，为相关设计提供参考。”摘要：BackgroundBandwidth limiting (BWL) neutron chopper is one of the important devices installed on the time-of-flight neutron scattering spectrometer. The BWL chopper can select the wavelength range of neutrons and filter the pulse period overlapping background by means of the periodically rotating disk, so as to improve the signal-to-noise ratio.PurposeThis study aims to verify whether the performance of the BWL choppers installed on the neutron scattering spectrometer of China Spallation Neutron Source (CSNS) meets the engineering requirements; on the other hand, it can provide reference for the design of BWL chopper on to be constructed.MethodsFirst of all, based on the BWL chopper system installed on the general purpose powder diffractometer (GPPD) of CSNS, the performances of the BWL chopper were systematically studied by theoretical calculation. Then, Monte Carlo simulation software McStas was employed to calculate the performance of BWL with the physical parameters of neutron choppers. Finally, neutron beam experiments were carried out to measure the actual working performance of the BWL choppers.ResultsThe results show that the actual wavelength bandwidth is about 0.478 nm with less than 0.5% relative error to the target bandwidth of 0.48 nm. The BWL chopper has a significant effect on the filtering long-wave neutron background.ConclusionsThe BWL neutron chopper installed on GPPD of CSNS satisfies engineering needs, and can provide a reference for the design and improvement of the BWL in the neutron scattering spectrometer to be built in the future.关键词：Bandwidth limiting neutron chopper, Disk,;McStas, Neutron beam experiments
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发布时间：2024-10-25
ACCELERATOR, RAY TECHNOLOGY AND APPLICATIONS
- “科研人员成功制备64Cu标记单链DNA，为PET分子探针制备提供关键技术，体内分布实验为研究提供重要信息。”摘要：BackgroundDNA (DeoxyriboNucleic Acid) polyhedral structure has great potential in molecular imaging probe with good properties in model animals such as low toxicity, low immunogenicity and excellent in vivo stability.PurposeThis article aims to use positron emission computed tomography (PET) radionuclide 64Cu to label DNA single strands instead of SPECT radionuclide 99mTc, and to study the distribution and metabolism of 64Cu labeled DNA single strands in Kunming mice in vivo.MethodsSingle strand DNA (ssDNA) was coupled with chelating agent p-SCN-Bn-NOTA and incubated with 64Cu for a certain time to obtain NOTA-ssDNA. The labeling reaction was monitored by thin layer chromatography, and purified by NAP-5 desalting column to obtain 64Cu-ssDNA. After injection into Kunming mice, the radioactive uptakes of organs of interest at different time were studied.ResultsAfter NOTA-ssDNA reacted with 64Cu for 1 h, the radiochemical labeling rate is (66.4±2.85)%. After purification, the radiochemical purity is >95%. The in vitro stability experiments show that 64Cu-ssDNA can stably exist in PBS and mouse serum for at least 6 h. There was a certain uptake in the gastrointestinal tract and high radioactive uptake in both the kidney and bladder after 64Cu-ssDNA is injected into the mice, indicating that 64Cu-ssDNA is mainly excreted through the urinary system.ConclusionsSuccessful preparation of 64Cu-ssDNA is a critical step for the preparation of PET molecular probes based on DNA polyhedral. In vivo distribution experiment provides experimental control data for studying the in vivo biological distribution of 64Cu labeled DNA polyhedra.关键词：Single-stranded DNA;Copper-64 labeling;In vivo distribution
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发布时间：2024-10-25
NUCLEAR CHEMISTRY, RADIOCHEMISTRY, RADIOPHARMACEUTICALS AND NUCLEAR MEDICINE
- “在核仪控系统领域，基于Zynq-7000 SoC设计实现了基于UDP的千兆以太网传输系统，传输速度最高可达870 Mbps，满足实际传输需求。”摘要：BackgroundWith the increasing complexity, integration level and data volume of nuclear instrumentation and control system, conventional data buses, such as peripheral component interconnect (PCI) or controller area network (CAN), are difficult to meet the needs of rapid data transmission.PurposeThis study aims to design and implement a Gigabit Ethernet transmission system based on the Xilinx's Zynq-7000 system on chip (SoC) and user datagram protocol (UDP).MethodsFirst of all, the system architecture of UDP Gigabit Ethernet transmission system for nuclear instrumentation and control system was introduced in detail. Then the ModelSim toolkit was employed to verify designed system functions by simulation. Finally, the Gigabit Ethernet transmission system was implemented using ZC706 development board, and tested by experiment.ResultsExperimental results show that the data transmission speed can reach 870 Mbps.ConclusionsThe Gigabit Ethernet transmission system can meet the actual transmission requirements of most nuclear instruments and control system.关键词：Zynq-7000;User datagram protocol (UDP);Ethernet;Transmission system
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发布时间：2024-10-25 - “报道：中国散裂中子源大气中子谱仪采用GEM探测器，通过蒙特卡罗仿真优化设计，实现2.9毫米位置分辨率。”摘要：BackgroundThe GEM (gas electron multiplier) detector with polyethylene conversion layer has the performance of fast neutron detection, high timporal resolution and spatial resolution. It is an ideal choice for fast neutron beam monitor for China spallation neutron source (CSNS).PurposeThis study aims to optimize the design of the GEM detector with polyethylene to meet its application requirements of the atmospheric neutron spectrometer of CSNS.MethodsFirst of all, the physical process of the detector was simulated by Monte Carlo simulation software Geant4 (GEometry ANd Tracking, version 4). The relationship between neutron detection efficiency of three different energies (7 MeV, 10 MeV and 14 MeV) and the thickness of polyethylene conversion layer was studied by simulation, and the influences of different thickness of barrier layer on energy and angle of recoil proton along with detection efficiency were investigated. Then, the energy deposition of recoil protons in gas with different thickness was calculated, and the γ-ray sensitivity of the detector was studied by simulation. Finally, the prototype detector was fabricated using simulated parameters, and a preliminary neutron beam experiment was carried out.ResultsThe results show that the detection has good two-dimensional imaging ability when the detector adopts 2 mm thick polyethylene, 200 µm thick aluminium barrier layer and 4 mm thick working gas. The spatial resolution of this detector can reach 2.9 mm.ConclusionsThis GEM based neutron detector meets the requirements of CSNS beam monitoring, which provides a reference for the optimal design of fast neutron beam monitor.关键词：GEM;Fast neutron;Spatial resolution;Beam monitoring
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发布时间：2024-10-25 - “兰州重离子加速器电源系统研究取得新进展，专家建立了高精度数字化电源脉冲标定体系，为提高电源输出电流精度提供解决方案。”摘要：BackgroundThe power supply system is one of the important systems of heavy ion research facility in Lanzhou (HIRFL). The stability and accuracy of its current directly affect the quality of beam, hence it is necessary to calibrate the DC Current Transducer (DCCT) of approximately 100 high precision digital pulse power supplies on the the main cooling storage ring (CSRm) and the experimental cooling storage ring (CSRe).PurposeThis study aims to establish a digital power supply pulse calibration system for all those power supplies to ensure the accuracy and consistency of HIRFL beam.MethodsBased on the principal of pulse calibration algorithm, a current calibration system of high precision digital power supply was proposed. The hardware composition, software architecture, calibration algorithm and data processing method of the system were described in details. The given coefficient and the read coefficient were obtained according to the analysis, processing and calculation of the collected current data.ResultsThe calibration results show that the accuracy of standard output current is improved by one order of magnitude, and the accuracy of read back value is improved by more than two orders of magnitude.ConclusionsCurrent calibration method proposed in this study can effectively ensure the output current accuracy and the read current accuracy of the high precision digital pulse power supply.关键词：Calibration system;High precision digital power supply;Given coefficient;Read coefficient
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发布时间：2024-10-25 - “在γ谱仪测量领域，专家提出了天然放射性核素特征峰稳谱法，有效识别并矫正峰漂现象，为实验室工艺系统样品γ核素测量提供解决方案。”摘要：BackgroundThe "peak drift" is an important factor affecting the measurement accuracy of the γ spectrometer.PurposeThis study aims to quickly identify and correct the "peak drift" of the high-purity germanium (HPGe) γ spectrometer in laboratory.MethodsA novel "the natural radionuclide characteristic peak spectrum stabilization method" was proposed in detail. Instead of characteristic energy peak of standard radioactive source, this method made use of the characteristic peak of natural radionuclide K-40 to identify "peak drift" and correct the "peak drift" of HPGe γ spectrometer. The effectiveness of this method on the ORTEC HPGe gamma spectrometer was verified by using liquid multi nuclide standard source and standard point source 60Co.Results & ConclusionThe results show that this "natural radionuclide characteristic peak spectrum stabilization method" has advantages of simple operation, fast peak recognition, and real-time accurate correction, which is suitable for the measurement of the γ nuclides in laboratory process system samples.关键词：HPGe γ spectrometer;Peak drift;Spectrum-stabilization
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发布时间：2024-10-25
NUCLEAR ELECTRONICS AND INSTRUMENTATION
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Adsorption and migration of uranium from Guangdong associated radioactive solid wastetored soil AI导读
“在伴生放射性固体废物处理领域，研究了铀在广东红壤中的吸附迁移规律，发现提高废物pH可降低铀的浸出与迁移。”摘要：BackgroundThe associated radioactivity solid waste (ARSW) is one kind of slight uranium mine with high activity of radioactive nuclides 238U and 232Th. There are few reports about the migration of uranium from ARSW in the literature. There are abundant radioactive mines in Guangdong province. Therefore, it is of great significance to study the adsorption and migration behavior of uranium from ARSW in Guangdong environment.PurposeThis study aims to investigate the adsorption and migration behavior of uranium in red soil in Guangdong province, hence provide technical support and reference for the treatment of ARSW.MethodsFirstly, the associated radioactive solid wastes were studied by column leaching experiment in 14 cm columns with natural rainwater lasted for 100 days. And the uranium concentrations migrated into red soil from ARSW were measured. Secondly, the batch dynamic and static adsorption experiments of uranium in red soil were performanced with uranyl nitrate.ResultsThe experimental results show that the uranium leaching rate of ionic acid solid waste, monazite waste and tantalum niobium acid solid waste are 41.1%, 0.015% and 97.8% respectively in natural rain water column leaching experiments. The migration of uranium in red soil is related to the existence of uranium. The water-soluble uranium (e.g., phosphoruranylite) is easier to migrate in red soil and increases with the increase of solubility. The adsorption isotherm of uranyl nitrate in red soil conforms to linear equation with a low partition coefficient Kd and a weak adsorption capacity of the red soilabout uranyl nitrate.ConclusionsIn order to reduce the leaching rate and motility of uranium, the pH of ARSW should be raised to convert the uranium into insoluble form.关键词：Associated radioactive solid wastes;Uranium;Red soil;Adsorption migration- 371
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发布时间：2024-10-25 - “在稀有衰变实验中，铜表面放射性本底抑制取得新进展。研究人员采用5%柠檬酸加8%双氧水酸洗配方，有效去除铜表面210Po，去除效率高达99.93%。”摘要：BackgroundCopper is one of materials often used in rare decay experiments due to its low intrinsic radioactivity. During the installation and assembly of detectors, copper parts may be exposed to air-born radon, therefore the decay daughters of radon (210Pb, 210Bi and 210Po) will be deposited on copper surfaces, and their α, β and γ decays will result in the increase of the experimental radioactive background.PurposeThis study aims to suppress this background by carefully cleaning the radioisotopes on copper surface.MethodsFirst of all, eight pickling recipes were used to test the efficacy of 210Po removal from copper surfaces. Copper test samples were prepared by exposing to high concentration radon gas environment. Then, counting rates of deposited 210Po on copper surfaces were measured by an alpha detector before and after cleaning for the calculation of 210Po removal efficiency. The relationship between removal efficiencies and concentration of pickling cocktails were investigated and pickling recipe with the highest removal efficiency was obtained. Finally, with the highest removal efficiency pickling cocktail, the radioactivity of 232Th/238U on copper surface was measured by an inductively coupled plasma mass spectrometry (ICP-MS) to estimate the radioactive contamination level in passivation layer.ResultsMixing 5% C6H8O7 and 8% H2O2 as pickling solution can remove 99% of 210Po, and 232Th/238U concentration in passivation layer is less than ng·g-1 level.ConclusionsThis best pickling recipe found by this study can be used in rare decay experiments to remove radon daughters (210Po) from copper surfaces to suppress the background induced by radon daughters.关键词：Copper;Radon daughters;α detector;Pickling and passivation;ICP-MS
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发布时间：2024-10-25 - “在放射性核素分析领域，专家提出了一种基于约束非线性最优化的重峰解析方法，有效降低了高统计涨落能谱重峰的峰面积相对误差，为复杂能谱解析提供解决方案。”摘要：BackgroundThe measurement and analysis of γ ray spectrum are important means of qualitative identification and quantitative analysis of radionuclides. The analysis of overlapping peaks in complex spectra has always been a difficult problem. The traditional fitting method has greater uncertainty when processing data with high complexity and high statistical fluctuations.PurposeThis study aims to propose an improved method to achieve more accurate overlapping peak analysis.MethodsFirst of all, an overlapping peak analysis method based on constrained nonlinear optimization was proposed by using system calibration data, hence the peak width constraint was added to the conventional nonlinear least squares fitting of overlapping peaks, making the results more physically consistent. Then a simple iterative method was designed to solve the constrained optimization problem by transforming the constraints into real-time updates of peak width and weight coefficients, and its performance was investigated by simulated data under different statistical fluctuations, peak distance and peak area ratio. Finally, the method was verified by the spectra of 152Eu and 133Ba point sources measured by LaBr3(Ce) and NaI(Tl) spectrometers.ResultsThe results show that the errors of peak parameters such as peak position, full width at half maximum (FWHM) and peak area obtained by the proposed method are significantly lower than those of the unconstrained method. For spectra with high statistical fluctuations, the relative error of the analytic peak area can be reduced by more than 50%.ConclusionsMaking full use of known information such as FWHM calibration can constrain the results of nonlinear fitting in a more accurate range, effectively improving the accuracy of overlapping peak analysis. This method is suitable for complex spectrum analysis.关键词：γ spectrum analysis;Overlapping peak analysis;Nonlinear fitting;Constrained optimization
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发布时间：2024-10-25
NUCLEAR PHYSICS, INTERDISCIPLINARY RESEARCH
- “在核能领域，研究人员开发了基于EPICS平台的S7plc驱动程序，实现了钍基熔盐固态仿真堆控制系统与保护系统的整合，满足核电人因工程要求，为核反应堆安全运行提供保障。”摘要：BackgroundThe operation control and safety protection functions of thorium molten salt reactor-solid fuel (TMSR-SF0) are independently implemented by the distributed control system based on experimental physics and industrial control system (EPICS) and a protection system based on field programmable gate array (FPGA). Since the protection system is set up to ensure the ultimate safety of the reactor, it is the most important part of the reactor control system for the safe operation of the reactor. Therefore, it is compulsory for integrating these two systems to meet the regulatory requirements of nuclear power human factors engineering.PurposeThis study aims to realize the real-time communication between the protection system and control system for TMSR-SF0.MethodsA distributed control system based on EPICS was designed and implemented to communicate with the protection system. The communication scheme between TMSR-SF0 control system and protection system was designed via the S7plc driver based on EPICS platform, and implemented by constructing the software input/output controller (IOC), configuring S7plc driver, designing IOC real-time database, developing the man-machine interface. Control system studio (CSS) was adopted to implement the display of communication scheme, and communication scheme was tested systematically by pre-set experiments.ResultsThe test results show that the TMSR-SF0 control system can stably communicate with the serial device of the protection system for accurate data acquisition in real-time through this proposed communication scheme, satisfying all technical indexes and requirements of TMSR-SF0 control system.ConclusionsThe communication scheme of the S7plc driver based on the EPICS platform and the communication protocol defined by protection system can be used to implement scheme for communication between the TMSR-SF0 control system and the protection system, providing reference for similar communication design.关键词：TMSR;EPICS;Control system;S7plc;Serial device
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发布时间：2024-10-25 - “在核设施放射性物质控制领域，专家重新计算了氚的导出空气浓度和水中活度浓度控制限制值，为辐射防护管理提供参考。”摘要：BackgroundTritium is one of the radionuclides released during the operation of nuclear facilities. The radiation hazard of tritium to human body is internal exposure, which is not only related to the activity of tritium, but also closely related to the chemical form and intake route of tritium. In view of the current standards involving tritium, there is an inconsistency in the control limit of tritiated water (HTO), as well as elemental tritium (HT).PurposeThis study aims to derive and standardize the concentration limits of HTO and HT, as well as the discharge activity concentration limits of HTO.MethodsThe development of tritium concentration control limits and the basis for the formulation of relevant standards were analyzed. According to the current radiation protection standards of China, combined with the latest biodosimetry parameters of tritium in publications of International Atomic Energy Agency (IAEA) and International Commission on Radiological Protection (ICRP), the control limits of derived air concentration (DAC) and water activity concentration for tritium were recalculated. When calculating the recommended limit of air concentration derived from HTO, the skin absorption was converted into the inhalation, and the complete skin absorption was set to half of the inhalation.ResultsSince the dose conversion coefficient used in the current standard is close to that in the new international publications, the recommended limits of HTO are slightly smaller than that specified in the standard, and the corresponding values are basically in the same order of magnitude.ConclusionsThe derived results can provide reference for the standard formulation of radiation protection management. The applicable objects of control limits are also clearly exhibited and distinguished. These objects are only available for people, not for facilities or equipment.关键词：Tritiated water (HTO);Elemental tritium (HT);Derived air concentration;Control limit;Internal exposure
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发布时间：2024-10-25
NUCLEAR ENERGY SCIENCE AND ENGINEERING
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