最新刊期
卷 43 ， 期 1 ， 2020
- “在X射线间接成像领域，专家利用冗余信息重构点扩散函数，为提高图像质量提供新方案。”摘要：BackgroundThe point spread function (PSF) of X-ray indirect imaging system is difficult to measure accurately through experiments, and the theoretical construction process is complex, hence it is difficult to meet the actual situation, resulting in poor image quality.PurposeThis study aims to obtain the PSF of X-ray indirect imaging system by reconstructing PSF with redundant information to obtain a more accurate PSF under incoherent illumination.MethodsFirst of all, theoretical analysis was performed for the measuring problem of incoherent optical PSF. Since the optical transfer function (OTF) was the fourier transform of PSF, and coherent transfer function (CTF) was closely related to OTF, nonlocality of incoherent optical information distribution was used to reconstruct the central region of the PSF. Then, the redundent information in a 2D grating scintillation imaging system was extracted to reconstruct the PSF by converting incoherent diffraction field to coherent diffraction field. Finally, experimental data obtained from BL13W beamline station of Shanghai synchrotron radiation facility (SSRF) were employed to evaluate PSF and image restoration results of scintillator imaging system.ResultsExperimental results of synchrotron radiation imaging show that this method can recover the image more accurately than other PSF measurement methods.ConclusionThe PSF reconstructed by redundant information method can not only restore the image accurately, but also avoid a lot of complex problems.关键词：X-ray;Scintillator imaging;Information redundancy;Point spread function
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发布时间：2024-10-25
SYNCHROTRON RADIATION TECHNOLOGY AND APPLICATIONS
- “华中科技大学研发的质子治疗装置Kicker磁铁测磁系统，通过电磁感应法测量磁场均匀度和动态特性，满足设计指标。”摘要：BackgroundA proton therapy facility based on superconducting cyclotron is under development in Huazhong University of Science and Technology Proton Therapy Facility (HUST-PTF). In HUST-PTF system, a kicker magnet upstream of the degrader is used to realize the fast switch on/off for the spot scanning process and the treatment safety.PurposeThis study aims to measure the integral field and the dynamic performance of the kicker magnet and implement a magnetic measurement system based on induction method.MethodsFirst of all, two different schemes (long coil and PCB coil) were adopted in the magnetic measurement system to obtain the induced voltage. Then, the induction voltage signals acquired by induction coils were integrated by analog or digital integrators. Experimental data analysis was performed to evaluate these two schemes, and final solution for magnetic measurement system was determined.ResultsExperimental results show that PCB coils with high geometric accuracy and RC integrators, less sensitive to zero drift, hence are adopted as the final solution of the measurement system. The overall error of the magnetic measurement system is less than 0.1%. The experimental results show that response time is less than 100 μs, the integral field greater than 0.025 2 T·m, integral field uniformity is better than 1%, and maximum standard deviation of uniformity is 0.006%.ConclusionsThe kicker magnet and its measurement system meet the design specifications.关键词：Kicker magnet;Integral magnetic field;Dynamic performance;RC integrator;PCB coils
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发布时间：2024-10-25 - “在医用直线加速器模拟领域，专家利用蒙特卡罗软件包，针对不同型号加速器，模拟计算入射电子打靶能量对剂量分布的影响，为快速确定打靶能量提供方法。”摘要：BackgroundMonte Carlo method provides a powerful tool for the simulation of particle transport in radiotherapy, hence can be used for determination of the target energy of the incident electron in medical linac simulation.PurposeThis study aims to find a way that can confirm the incident electron energy accurately and quickly, and save time for Monte Carlo linac simulation.MethodsFirst of all, Monte Carlo program package EGSnrc/BEAMnrc was employed to build up the beam models of Varian 600C, Trilogy and Edge FFF (Flattening Filter Free) model with the same nominal energy of simulation of 6 MV. Then, the dose distributions in different fields (3 cm×3 cm, 10 cm×10 cm, 40 cm×40 cm) using different incident electron energies in water phantom were calculated. Finally simulation results were compared and analyzed to find out a way to ensure the incident electron energy accurately and quickly.ResultsWhen the incident electron energy varies from 5.5 MeV to 6.5 MeV, percentage depth dose (PDD) is insensitive to the incident electron energy; the off axis ratio (OAR) profiles of 3 cm×3 cm and 10 cm×10 cm are insensitive to the incident electron energies, the OAR profiles of different incident electron energies are almost the same. The OAR profile of 40 cm×40 cm is very sensitive to the incident electron energy. Detailed results at 5 cm underwater show that when the incident electron energy increases by every 0.1 MeV, the average of OAR between the off axis distance from 14.5 cm to 19 cm decreases: 0.82% for Varian 600C 6 MV, 0.98% for Trilogy 6 MV, 0.47% for Edge 6 MV FFF, respectively. Combining the measured OAR profiles of large field (40 cm×40 cm) with the linear relationship between average OAR and the incident electron energy, the incident electron energy can be determined quickly. Compared with the measured values, the PDD and OAR using the fitting energy as input in water phantom, profiles differences are both within 1%.ConclusionsThis proposed method provides a way to ensure the incident electron energy accurately and quickly for medical linac.关键词：Medical linear accelerator;Incident electron shooting energy;Varian 600C trilogy edge;Monte Carlo simulation
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发布时间：2024-10-25 - “在MeV能区γ射线天文研究领域，科学家设计了一种新型双端读出γ射线探测器，采用SiPM匹配CsI(Tl)晶体，能量分辨率达5.9%，位置分辨率约5.7mm，为下一代康普顿望远镜提供关键技术支撑。”摘要：BackgroundCompared with other energy regions, little research of gamma-ray astronomy in the MeV energy region has been carried out, hence insufficient exploration of astrophysical information is available in the MeV energy region.PurposeThis study aims to investigate the gamma-ray astronomy of MeV energy region so as to provide reference for the design of the next generation Compton telescope calorimeter.MethodsA dual-ended readout gamma-ray detector was designed as the elementary detection unit of a calorimeter. The detector was made of a long CsI(Tl) bar with the size of 10 mm×10 mm×80 mm and wrapped by the ESR film. The photodiode (PD), the avalanche photodiode (APD) and the silicon photomultiplier tube (SiPM) were used respectively as photoelectric converters for the detector, and they were tested by using 137Cs source at different positions on the detector.ResultsThe results show that the total energy and interaction position of the incident gamma-ray can be determined by reading the signal amplitudes at two ends of the three photoelectric converters. The energy resolution for 662 keV gamma-ray is 5.9% (full width at half maxima, FWHM) and the position resolution is about 5.7 mm (FWHM), which is the best performance obtained in the case of SiPM readout.ConclusionsThe detection unit designed in this paper can meet the performance requirements of the calorimeter of the next generation Compton telescope.关键词：Calorimeter;Dual-ended readout;CsI(Tl) crystal;Energy resolution;Position resolution
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发布时间：2024-10-25 - “纳米Al2O3/ZrO2复合陶瓷在高温稳定性和化学稳定性方面表现出色，专家通过XRD、TEM等技术深入研究了其微结构及缺陷，为纳米陶瓷材料发展提供新思路。”摘要：BackgroundAl2O3/ZrO2 nano-composites have excellent mechanical properties, high temperature stability and chemical stability, as well as good anti-irradiation effect. It is a potential nano-composites in practical industry.PurposeThis study aims to investigate the microstructures and defects of Al2O3/ZrO2 nano-composites at different annealing temperatures (room temperature -1 000 ℃) by positron annihilation lifetime spectroscopy (PALS).MethodsThe Al2O3 and ZrO2 nanoparticle powder with a mass ratio of 1:1 was ball-milled for 10 h and then pressed into pellets under a pressure of 5 MPa for 2 min. PALS was employed for detecting open-volume defects while X-ray diffraction (XRD) and transmission electron microscope (TEM) were used as auxiliary comparison tools for analyzing microstructures under various annealing temperatures.ResultsXRD results showed that the grain sizes of Al2O3, ZrO2 and Al2O3/ZrO2 nano-composites remained unchanged with annealing temperature below 500 ℃. With the increasing of annealing temperature from 500 ℃ to 1 000 ℃, the grain sizes of ZrO2 and Al2O3/ZrO2 increased to 75 nm and 115 nm, respectively. PALS analysis showed that the main defects in the samples were vacancies, vacancy clusters and microvoids, and the defects mainly existed in the grain boundaries. When the annealing temperature was below 500 ℃, the total defect densities of the three samples were basically unchanged. Above 500 ℃, the open volume defects began to recover, and the change of ZrO2 was more obvious, while the stability of Al2O3/ZrO2 was higher because of inhibiting each other's grain growth. TEM images revealed that the grain size of nano-Al2O3 did not change with the annealing temperature below 500 ℃, but when the annealing temperature was higher than 500 ℃, the growth of nano-Al2O3/ZrO2 was slow and agglomeration occurred.ConclusionsBoth grain size and defect density of Al2O3/ZrO2 nano-composites remains unchanged with annealing below 500 ℃. Above 500 ℃, with the increase of annealing temperature, the grain of nano-Al2O3/ZrO2 grew slower than nano-ZrO2 and the openning volume defects began to recover which was confirmed by TEM observation.关键词：Positron annihilation;Microstructure;Defects;Annealing;Nano-composites
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发布时间：2024-10-25
ACCELERATOR, RAY TECHNOLOGY AND APPLICATIONS
- “在环境治理领域，研究人员通过H2O2活化活性炭，制备出高效吸附材料15%-AC，显著提升了对U(Ⅵ)的吸附性能。”摘要：BackgroundUranium pollution to water environment is becoming more and more serious. U(VI) has become the main research object because of its special physical and chemical properties. Although ordinary activated carbon is easy to obtain and cheap, its adsorption properties for U(VI) need to be improved.PurposeThis study aims to improve the adsorption performance of activated carbon for U(VI) by clean and harmless hydrogen peroxide.MethodsThe activated carbon before and after activation was characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscope (SEM) and Brunauer-Emmett-Teller (BET) theory. The mechanism of activated carbon activated by hydrogen peroxide was investigated. The sorption behavior of U(VI) on activated-carbon was studied as a function of contact time, pH value, solid-to-liquid ratio, initial concentration, temperature and ionic species of U(VI) by the static experimental method.ResultsThe results showed that the oxidized groups on the surface of the treated activated carbon increased, and more adsorption sites were formed. The specific surface area decreased slightly whereas the mesoporous content and porosity increased. Under the optimal conditions (contact time, pH, solid-liquid ratio, initial concentration, temperature were 90 min, 5, 8 g·L-1, 80 mg·L-1, 35 ℃, respectively), the adsorption performance was improved by 68%. The quasi second-order kinetic model and Langmuir isotherm adsorption model fitted the adsorption behavior well, and the adsorption behavior was homogeneous and multi-element. 15%-AC still had good adsorption performance under the influence of coexisting ions and cyclic adsorption.ConclusionsExperiments show that the activation process of H2O2 can effectively improve the adsorption of U(Ⅵ) on activated carbon.关键词：Activated-carbon;Hydrogen peroxide;Activation;Adsorption;U(VI)
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发布时间：2024-10-25
NUCLEAR CHEMISTRY, RADIOCHEMISTRY, RADIOPHARMACEUTICALS AND NUCLEAR MEDICINE
- “在放射性监测领域，专家利用点源模拟法提高测量下限，为核电单位测量提供新方案。”摘要：BackgroundWhen the radiation source term lifetime is short and there is a cascade relationship, the standard volume source is difficult to prepare and the background count is too high. In order to solve these two problems, an experimental method based on point source simulation is proposed.PurposeThis study aims to improve the lower limit of radioactivity monitoring instrument by using coincidence technology to reduce the effect of background count.Methods22Na point source was taken as possible replacement of the standard 13N volume source term. The coincidence detection efficiencies of omnipotence peak of 13N with a diameter of 290 mm, 300 mm, 350 mm, 400 mm were measured while the simulation calculation of those efficiencies was carried out with Geant4 software. The experimental measurement results were compared with simulation results.ResultsWithin the error range of 9.2%, the experimental results are consistent with the simulation results.ConclusionsThe results show that proposed method is feasible and reliable, and can be used in practical nuclear power sheet.关键词：Point source simulation test;Short-life source term;Omnipotence peak;Coincidence efficiency
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发布时间：2024-10-25 - “CMOS图像传感器在空间应用中受粒子辐照影响，专家综述了其单粒子效应研究进展，为相关研究提供理论参考。”摘要：BackgroundCMOS imager sensors (CISs) used in the space radiation environments are susceptible to single event effects (SEEs), which can cause images corruption and even CIS function failure.PurposeThis study aims to evaluate the progress of SEEs and hardening technology of CIS.MethodsIn this paper, the SEEs on the CIS are reviewed by summarizing the investigation from different particles such as heavy ions, protons, electrons and neutrons, and from different types of SEEs: including single event transient (SET), single event upset (SEU), single event functional interrupt (SEFI) and single event latch-up (SEL). Progresses of SEEs hardening technology on CIS are briefly investigated.Results & ConclusionsThis paper analyzes the SEEs and problems to be solved urgently on hardening technology on the CIS technology, which provides theoretical reference for further researches in the future.关键词：CMOS image sensor;Single event effects;Radiation hardening technology;Space radiation
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发布时间：2024-10-25 - “在探测技术领域，专家建立了随钻方位γ能谱测井仪探测特性研究体系，为仪器结构优选设计及资料解释提供解决方案。”摘要：BackgroundThe detection characteristics of the spectral azimuthal γ-ray (SAGR) logging while drilling (LWD) tool are important for the early design of the instrument structure and subsequent interpretation of the logging data, so it is necessary to study its detection characteristics and its influencing factors.PurposeThis study aims to investigate the effects of wellbore size, mud density, formation density, and natural radioactive material types on the SAGR instrument detection characteristics.MethodsFirst of all, the instrument structure of the LWD spectral azimuthal gamma ray tool was determined, then the corresponding MCNP model was established. Based on the geometric factors in the induction logging, the radial, longitudinal and circumferential integral geometry factors of the SAGR instrument were simulated. Finally, the influence of wellbore size, mud density, formation density and different natural radioactive materials on the detection characteristics of the SAGR were studied by simulation.ResultsThe results show that the wellbore size, formation density and natural radioactive material types have a great influence on the SAGR detection characteristics, while the mud density have no effect.ConclusionThis study provides a theoretical reference for instrument design and logging data interpretation of the spectral azimuthal γ-ray logging while drilling tool.关键词：LWD spectral azimuthal γ-ray;Geometric factors;Numerical simulation
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发布时间：2024-10-25
NUCLEAR PHYSICS, INTERDISCIPLINARY RESEARCH
- “中国聚变工程实验堆增殖包层采用多模块设计，通过增加低场侧极向分块数目，可有效降低等离子体大破裂工况产生的电磁力和力矩，提高结构稳定性。”摘要：BackgroundThe multi module segment (MMS) proposal was adopt for the design of the breeder blanket for the China Fusion Engineering Test Reactor (CFETR) reactors. The breeder blanket system is divided into 16 toroidal sectors of 22.5° with the inboard (IB) and outboard (OB) blanket modules maintained together with the back plate support. When a plasma major disruption or vertical displacement event occurs, a large electromagnetic (EM) loads generated on the breeder blanket will applied to the back plate system.PurposeThe aim is to study the influence of the poloidal segmentation of breeder blanket of CFETR on the electromagnetic load distribution.MethodsThe finite element models with different poloidal segmentations were developed in ANSYS code to simulate a plasma large break with 36 ms exponential current quenching. The eddy current, Lorentz forces and moments on U-shaped casing of Helium Cooled Ceramic Breeder (HCCB) were calculated by transient analysis. Furthermore, the effect of EM loads on the back plate poloidal segmentations was studied.Results & ConclusionsThe results show that when the EM forces and moments of the inboard blanket barely changed little, the outboard blanket changed greatly. With the number of poloidal segmentations increases, the total EM forces load on the back plate will decrease. Those results may provide important data support for the subsequent optimization of the back plate of CFETR.关键词：CFETR;Helium cooled ceramic breeder;Plasma major disruption;EM force and moment
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发布时间：2024-10-25 - “在反应堆结构动力学领域，研究者基于势流体声学有限元理论，采用ADINA软件和共节点网格技术，对HDR实验堆失水事故进行数值模拟，提供了一种简单高效的分析方法。”摘要：BackgroundDynamic response of reactor internals due to loss-of-coolant accident (LOCA) is one of the main issues in structural dynamics of nuclear reactors. Current analysis methods mainly adopt computation fluid dynamics (CFD) based fluid-structure interaction approaches, which have high numerical accuracy but pay the price of high computational cost.PurposeThis study aims to propose acoustic finite element method for dynamic analysis of reactor internals induced by loss-of-coolant accident.MethodsDisplacements of both fluid and structure and the pressure of fluid were taken as basic unknown variables in this flow acoustic finite element method. The commercial code, ADINA, together with conforming mesh along the fluid-structure interface, was utilized to model the V32 experiment of the Germany HDR (Heiss Dampf Reaktor) reactor.ResultsThe acoustic-structure coupling results agree well with the experimental results reported in reference and the results given by CFD-based two-way coupling method whilst relative lower computation cost and ease implementation are achieved.ConclusionsThe study provides a straightforward and efficient method for engineering nuclear LOCA dynamic analysis.关键词：LOCA;Reactor internals;Dynamic response;Fluid-structure interaction;Acoustic finite element
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发布时间：2024-10-25 - “在核电技术领域，专家采用三维数值模拟研究了稳压器波动管中气液相向流动限制现象，为提高反应堆安全性提供解决方案。”摘要：BackgroundPassive automatic pressure relief system is widely used in the third generation nuclear power technology to improve the safety of the reactor. However, the counter-current flow limitation (CCFL) which may be caused by a rupture accident will increase the safety risk of the pressurizer surge line itself. Therefore, it is very important to study the CCFL phenomenon in the pressurizer surge line.PurposeThis study aims at numerical simulation of the phenomenon of CCFL in the pressurizer surge line.MethodsThe free surface model and modified algebraic interfacial area density (AIAD) model were used to simulate the CCFL phenomenon by ANSYS CFX software. By comparison with corresponding experimental phenomena, the model used for the simulation of the interphase action of the two phases under this phenomenon was evaluated.ResultsResults of the sensitivity analysis of the gas phase velocity and inclined angle show that the advance of the slug is mainly affected by the initial gas phase velocity and the surge line inclination angle of the pressurizer. The position near the initial gas phase velocity of the surge line is mainly affected by the initial gas phase velocity, while the position away from the pipeline initial point is mainly affected by the inclined angle.ConclusionsThe CCFL phenomenon can be clearly reflected by using free surface model and modified AIAD models which is consistent with the experimental results.关键词：CCFL phenomenon;Pressurizer surge line;Modified algebraic interfacial area density model
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发布时间：2024-10-25 -
Th-U and U-Pu cycling performances of molten chloride salt fast reactor under LEU start-up mode AI导读
“在核能领域，研究人员基于2500MW氯盐快堆，分析了Th-U与U-Pu循环的性能，发现U-Pu循环增殖性能优于Th-U循环，但Th-U循环安全性能更好。”摘要：BackgroundCompared with molten fluoride salt fast reactor, molten chloride fast reactor (MCFR) has higher solubility of heavy metals, harder neutron energy spectrum, and better breeding performance, hence an ideal type of reactor for realizing closed fuel cycle.PurposeThis study aims to analyze and compare Th-U and U-Pu cycle performances of MCFR.MethodsBased on the 2 500 MW molten chloride salt fast reactor, the TMCBurnup and MESA codes were used to analyze the transition and equilibrium states of Th-U and U-Pu cycles with Low Enriched Uranium (LEU) as the starting fuel. Two different transition modes were analyzed from the perspectives of nuclide evolution, proliferation, safety and radioactivity.ResultsThe results show that U-Pu cycle has better breeding performance than Th-U cycle. In breeding and burning (B&B) mode, the breeding ratios of the U-Pu and Th-U cycle are 1.56 and 1.24, respectively. The corresponding doubling time (DT) of the U-Pu and Th-U cycle is 13.5 years and 16.5 years, while in pre-breeding and burning (PB&B) mode, the replacement ratios are 1.58 and 1.08, and the doubling time is 12.8 years and 13 years, respectively. However, Th-U cycle has better safety performance, lower transuranic nuclides (TRU) accumulation and lower radiotoxicity.ConclusionsBoth Th-U and U-Pu cycle have good breeding performance in MCFR, and they can keep safety under all cycle modes. However, the U-Pu cycle has better breeding performance and the Th-U cycle has lower radiotoxicity and TRU accumulation, which reduces the difficulty of post-processing.关键词：MCFR;Fuel cycle;Breeding ratio;Transition mode- 340
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发布时间：2024-10-25
NUCLEAR ENERGY SCIENCE AND ENGINEERING
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