分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2022-08-08
A simpler and improved utility approximate point scattered function for thin-fifilm converters currently used in neutron photographic devices is proposed as a correction method to produce clearer, more realistic images. The validity of the model was demonstrated through a simulation experiment. Based on the results, an error analysis was carried out, certain corrections were made to the original model, and the fifinal model achieved a very low relative error in the simulation experiment. The model can also be optimized for quantitative neutron photographic analysis using iterative algorithms to obtain realistic neutron photographic images more quickly. At the end of the article, the model is extended to consider the case of energy spectrum hardening by introducing a temperature correction parameter.
分类： 核科学技术 >> 乏燃料后处理技术 提交时间： 2022-05-28
Nuclear material license holder should develop a nuclear material accounting management system and achieve the closed balance. According to regulations requirements, nuclear material accountancy implementation is based on physical inventory and material measurement. Generally, the spent fuel reprocessing plant operates uninterrupted, annual throughput of nuclear materials is huge, different measurement and analysis techniques are configured combing the reprocessing process. So the closed balance approach of nuclear materials accounting is a great challenge. In order to improve the accuracy and reliability of nuclear material, enhance the timeliness of abnormal detection, near-real time accounting prospect of spent fuel reprocessing plant was researched. In this paper, the crucial aspect affecting the closed balance of nuclear materials was discussed, the factors such as the head-end receiver-shipper difference, the on-line process monitoring accuracy, the applicability of the international target value of nuclear material measurement uncertainty, and also the nuclear material balance model of reprocessing plants. As summarized, proposed suggestions and solutions for nuclear material balance in spent fuel reprocessing plant was put forward on the end of the paper.
分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2022-05-20
A dilation X-ray detector (DIXD) based on time dilation and microchannel plate (MCP) gated technology has been reported. The DIXD passes a driving pulse along the transmission photocathode (PC) to obtain a dilated electron signal and finally achieves a high time resolution of 12 ps. Furthermore, the waveform of the PC driving pulse can be obtained using the DIXD, and a DIXD oscillographic function can be obtained. An experiment is presented to demonstrate the DIXD oscilloscope. The waveform of the PC driving pulse from points t1 to t12 is achieved by the DIXD. The waveform agrees well with that measured by a high-speed oscilloscope with a difference of less than 6%. The maximum theoretical bandwidth of the DIXD oscilloscope is theoretically studied. The bandwidth is limited by the potential difference between the PC and mesh. When the potential difference is 3.4 kV, the theoretical limiting bandwidth is 1000 GHz. The bandwidth increases with an increase in the potential difference.
分类： 核科学技术 >> 粒子加速器 提交时间： 2021-12-31 合作期刊: 《Nuclear Science and Techniques》
Ma, Jin-Ying
Qiu, Feng
Shi, Long-Bo
Zhu, Zheng-Long
Jiang, Tian-Cai
Xue, Zong-Heng
Jin, Ke-An
Chen, Qi
Xu, Cheng-Ye
Ding, Xing-Hao
Gao, Zheng
Sun, Lie-Peng
Huang, Gui-Rong
He, Yuan
摘要： Precise measurements of the cavity forward (Vf) and reflected signals (Vr) are essential for characterizing other key parameters such as the cavity detuning and forward power. In practice, it is challenging to measure Vf and Vr precisely because of crosstalk between the forward and reflected channels (e.g., coupling between the cavity reflected and forward signals in a directional coupler with limited directivity). For DESY, a method based on the cavity differential equation was proposed to precisely calibrate the actual Vf and Vr. In this study, we verified the validity and practicability of this approach for the Chinese ADS front-end demo superconducting linac (CAFe) facility at the Institute of Modern Physics and a compact energy recovery linac (cERL) test ma#2;chine at KEK. At the CAFe facility, we successfully calibrated the actual Vf signal using this method. The result demonstrated that the directivity of directional couplers might seriously affect the accuracy of Vf measurement. At the cERL facility, we calibrated the Lorentz force detuning (LFD) using the actual Vf. Our study confirmed that the precise calibration of Vf significantly improves the accuracy of the cavity LFD measurement.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2021-12-31 合作期刊: 《Nuclear Science and Techniques》
Ju, Xiao-Lu
Deng, Biao
Li, Ke
Yu, Fu-Cheng
Zhang, Hai-Peng
Xu, Ming-Wei
Du, Guo-Hao
Xie, Hong-Lan
Li, Bin
Xiao, Ti-Qiao
摘要： Doped elements in alloys significantly impact their performance. Conventional methods usually sputter the surface material of the sample, or their performance is limited to the surface of alloys owing to their poor penetration ability. The X-ray K-edge subtraction (KES) method exhibits great potential for the nondestructive in situ detection of element contents in alloys. However, the signal of doped elements usually deteriorates because of the strong absorption of the principal component and scattering of crystal grains. This in turn prevents the extensive application of X-ray KES imaging to alloys. In this study, methods were developed to calibrate the linearity between the grayscale of the KES image and element content. The methods were aimed at the sensitive analysis of elements in alloys. Furthermore, experiments with phantoms and alloys demonstrated that, after elaborate calibration, X-ray KES imaging is capable of nondestructive and sensitive analysis of doped elements in alloys.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2021-12-31 合作期刊: 《Nuclear Science and Techniques》
摘要： The radiation environment on the surface of Mars is a potential threat for future manned exploration missions to this planet. In this study, a simple geometrical model was built for simulating the radiation environment on the Mars surface caused by galactic cosmic rays (GCRs); the model was built and studied using the Geant4 toolkit. The simulation results were compared with the data reported by a radiation assessment detector (RAD).
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2021-12-31 合作期刊: 《Nuclear Science and Techniques》
摘要：Controllable D-D neutron sources have a long service life, low cost, and non-radioactivity. There are favorable prospects for its application in geophysical well logging, since traditional chemical radioactive sources used for well logging pose potential threats to the safety of the human body and environment. This paper presents an improved method to measure formation density that employs a D-D neutron source. In addition, the lithological effect on the measured density was removed to better estimate the formation porosity. First, we investigated the spatial distribution of capture gamma rays through Monte Carlo simulations as well as the relationship between the ratio of capture gamma ray counts and formation density to establish theoretical support for the design of density logging tools and their corresponding data processing methods. Second, we obtained the far to near detector counts of captured gamma rays for an optimized tool structure, and then established its correlation with the density and porosity of three typical formations with pure quartz, calcite, and dolomite minerals. Third, we determined the values for correcting the densities of sandstone and dolomite with the same porosity using limestone data as the reference and established the equations for calculating the correction values, which lays a solid foundation for accurately calculating formation porosity. We observed that the capture gamma ray counts first increased then decreased and varied in different formations; this was especially observed in high-porosity formations. Under the same lithologic conditions (rock matrix), as the porosity increases, the peak value of gamma ray counts moves toward the neutron source. At different detector-source distances, the ratio of the capture gamma ray counts was well correlated with the formation density. An equation of the formation density conversion was established based on the ratio of capture gamma ray counts at the detector-source distances of 30 cm and 65 cm, and the calculated values were consistent with the true values. After correction, the formation density was highly consistent with the true value of the limestone density, and the mean absolute error was -0.013 g/cm3. The calculated porosity values were very close to the true values, and the mean relative error was 2.33%, highlighting the accuracy of the proposed method. These findings provide a new method for developing D-D neutron source logging tools and their well-log data processing methods.
分类： 核科学技术 >> 辐射物理与技术 提交时间： 2021-12-31 合作期刊: 《Nuclear Science and Techniques》
摘要： The muon radiography imaging technique for high-atomic-number objects (Z) and large-volume objects via muon transmission imaging and muon multiple scattering imaging remains a popular topic in the field of radiation detection imaging. However, few imaging studies have been reported on low and medium Z objects at the centimeter scale. This paper presents an imaging system that consists of three layers of a position-sensitive detector and four plastic scintillation detectors. It acquires data by coincidence detection technique of cosmic-ray muon and its secondary particles. A 3D imaging algorithm based on the density of the coinciding muon trajectory was developed, and 4D imaging that takes the atomic number dimension into account by considering the secondary particle ratio information was achieved. The resultant reconstructed 3D images could distinguish between a series of cubes with 5-mm side lengths and 2-mm intervals. If the imaging time is more than 20 days, this method can distinguish intervals with a width of 1 mm. The 4D images can specify target objects with low, medium, and high Z values.
分类： 核科学技术 >> 粒子加速器 提交时间： 2021-12-31 合作期刊: 《Nuclear Science and Techniques》
Bai, Shi-Wei
Yang, Xiao-Fei
Wang, Shu-Jing
Liu, Yong-Chao
Zhang, Peng
Liu, Yin-Shen
Hu, Han-Rui
Guo, Yang-Fan
Wang, Jin
Du, Ze-Yu
Yan, Zhou
Zhang, Yun-Kai
Ye, Yan-Lin
Li, Qi-Te
Ge, Yu-Cheng
He, Chuang-Ye
摘要： Collinear laser spectroscopy is a powerful tool for studying the nuclear spins, electromagnetic moments, and charge radii of exotic nuclei. To study the nuclear properties of unstable nuclei at the Beijing Radioactive Ion#2;beam Facility (BRIF) and the future High Intensity Heavy-ion Accelerator Facility (HIAF), we developed a collinear laser spectroscopy apparatus integrated with an offline laser ablation ion source and a laser system. The overall performance of this state-of-the-art technique was evaluated and the system was commissioned using a bunched stable ion beam. The high-resolution optical spectra for the 4s 2S1/2 → 4p 2P3/2 (D2) ionic transition of 40,42,44,48Ca isotopes were successfully measured. The extracted isotope shifts relative to 40Ca showed excellent agreement with the literature values. This system is now ready for use at radioactive ion beam facilities such as the BRIF and paves the way for the further development of higher-sensitivity collinear resonant ionization spectroscopy techniques.
分类： 核科学技术 >> 裂变堆工程技术 提交时间： 2021-12-31 合作期刊: 《Nuclear Science and Techniques》
摘要： Nuclear data are the cornerstones of reactor physics and shielding calculations. Recently, China released CENDL-3.2 in 2020, and the United States released ENDF/B-VIII.0 in 2018. Therefore, it is necessary to comprehensively evaluate the criticality computing performance of these newly released evaluated nuclear libraries. In this study, we used the NJOY2016 code to generate ACE format libraries based on the latest neutron data libraries (including CENDL-3.2, JEFF3.3, ENDF/B-VIII.0, and JENDL4.0). The MCNP code was used to conduct a detailed analysis of fission nuclides, including 235U, 233U, and 239Pu, in different evaluated nuclear data libraries based on 100 benchmarks. The criticality calculation performance of each library was evaluated using three statistical parameters: , , and . Analysis of the parameter showed that CENDL-3.1 and JENDL-4.0 both had >10 benchmarks that exceeded 3σ, whereas CENDL-3.2, ENDFB-VIII.0, and JEFF-3.3 had, 7, 5, and 4 benchmarks, respectively, exceeding 3σ. The ENDF/B-VII.1 library performed best, with only two benchmarks exceeding 3σ. Compared with CENDL-3.1, CENDL-3.2 offers an improvement in criticality calculations. Compared with the JEFF-3.3 and ENDF/B-VIII.0 libraries, CENDL3.2 performs better in the calculation of the 233U assemblies, but it performs poorly in the pusl11 series case calculation of the 239Pu assemblies, and thus further improvement is needed.
分类： 核科学技术 >> 裂变堆工程技术 提交时间： 2021-12-31 合作期刊: 《Nuclear Science and Techniques》
摘要： The transport cross-section based on inflow transport approximation can significantly improve the accuracy of light water reactor (LWR) analysis, especially for the treatment of the anisotropic scattering effect. The previous inflow transport approximation is based on the moderator cross-section and normalized fission source, which is approximated using transport theory. Although the accuracy of reactivity is increased, the P0 flux moment has a large error in the Monte Carlo code. In this study, an improved inflow transport approximation was introduced with homogenization techniques, applying the homogenized cross-section and accurate fission source. The numerical results indicated that the improved inflow transport approximation can increase the P0 flux moment accuracy and maintain the reactivity calculation precision with the previous inflow transport approximation in typical LWR cases. In addition to this investigation, the improved inflow transport approximation is related to the temperature factors. The improved inflow transport approximation is flexible and accurate in the treatment of the anisotropic scattering effect, which can be directly used in the temperature-dependent nuclear data library.
分类： 核科学技术 >> 裂变堆工程技术 提交时间： 2021-12-31 合作期刊: 《Nuclear Science and Techniques》
摘要： The advantages of once-through molten salt reactors include readily available fuel, low nuclear proliferation risk, and low technical difficulty. It is potentially the most easily commercialized fuel cycle mode for molten salt reactors. However, there are some problems in the parameter selection of once-through molten salt reactors, and the relevant burnup optimization work requires further analysis. This study examined a once-through graphite moderated molten salt reactor using enriched uranium and thorium. The fuel volume fraction (VF), initial heavy nuclei concentration (HN0), feeding uranium enrichment (EFU), volume of the reactor core, and fuel type were changed to obtain the optimal conditions for burnup. We found an optimal region for VF and HN0 in each scheme, and the location and size of the optimal region changed with the degree of EFU, core volume, and fuel type. The recommended core schemes provide a reference for the core design of a once-through molten salt reactor.
分类： 核科学技术 >> 粒子加速器 提交时间： 2021-12-31 合作期刊: 《Nuclear Science and Techniques》
Chen, Jun-Yang
Tong, Jian-Fei
Hu, Zhi-Liang
Han, Xue-Fen
Tang, Bin
Yu, Qian
Zhang, Rui-Qiang
Zhao, Chong-Guang
Xu, Jun
Fu, Shi-Nian
Zhou, Bin
Liang, Tian-Jiao
摘要： An accelerator-based Boron Neutron Capture Therapy (AB-BNCT) experimental facility called D-BNCT01 has been recently completed and is currently able to generate a high-intensity neutron beam for BNCT related research. In this study, we perform several experiments involving water phantoms to validate the Monte Carlo simulation results and analyze the neutron beam characteristics. According to our measurements, D-BNCT01 may generate a neutron flux about 1.2×108 n/cm2/s at the beam port using a 5 kW proton beam. Our results, also show that the thermal neutron flux depth distribution inside the water phantom is in good agreement with simulations. We conclude that D-BNCT01 may be effectively employed for BNCT research.
分类： 核科学技术 >> 粒子加速器 提交时间： 2021-12-31 合作期刊: 《Nuclear Science and Techniques》
Ma, Zhen-Yu
Zhao, Shen-Jie
Liu, Xu-Ming
Yu, Yue-Chao
Jiang, Hong-Ru
Zheng, Xiang
Chang, Qiang
Zhang, Zi-Gang
Xu, Kai
Wang, Yan
Zhao, Yu-Bin
Hou, Hong-Tao
摘要： The Shanghai High Repetition Rate XFEL and Extreme Light Facility (SHINE) project will use 600 1.3 GHz fundamental power couplers, which are modified based on TTF-III power couplers, for continuous wave operation with input power up to approximately 7 kW. The first batch of 20 sets of 1.3 GHz coupler prototypes were fabricated from three domestic manufacturers for the SHINE project. To better characterize the radio frequency conditioning phenomena for validating the performance of power couplers, a room temperature test stand was designed, constructed, and commissioned for the SHINE 1.3 GHz power couplers. In addition, a horizontal test cryostat was built to test the 1.3 GHz superconducting cavities, fundamental power couplers, tuners, and other components as a set. The results of these tests indicate that the 1.3 GHz couplers are capable of handling up to 14 kW continuous waves. Herein, the main aspects of the radio frequency design and construction of the test stand, along with the test results of the high-power conditioning of the 1.3 GHz couplers, are described.
分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2021-08-07
摘要：合肥光源储存环束流位置检测器BPM的4路电极信号直接接入国产12bit分辨率、10Gsps采样率、2GHz带宽的示波器，采集程序运行在Zstack架构下的云主机上，每次触发读取500μs的一组波形，提取出45个束团2266圈束团质心的X（水平位置）、Y（垂直位置）、Z（纵向相位）信息，逐束团的X、Y的分辨率约为5μm，Z的分辨率约为0.5ps，在线运行更新周期7秒左右。得到的逐束团3维位置信息做频谱分析可得到运行常态时每个束团的3维工作点，对纽扣和条带电极信号的分析可得到激励时横向尺寸四极振荡的谱峰。
分类： 核科学技术 >> 核聚变工程技术 提交时间： 2017-10-27
摘要： Purpose – The purpose of this paper is to develop a serial redundant manipulator system applied in nuclear fusion environment. It will allow remote inspection and maintenance of plasma facing components in the vacuum vessel of fusion device without breaking down the ultra-high vacuum condition during physical experiments. Design/methodology/approach – Firstly, considering the dynamic sealing of actuators to avoid polluting the vacuum condition inside fusion reactor, the mechanical design of robot system has been introduced. The redundant manipulator system has 11 degree of freedoms in total with an identical modular design. Besides, to improve the position accuracy, an error prediction model has been built based on the experimental study and back-propagation neural network (BPNN) algorithm. Findings – Currently, the implementation of the manipulator system has been successfully finished in both atmosphere and vacuum condition. The validation of BPNN model shown an acceptable prediction accuracy (94%~98%) compared with the real measurement. Originality/value – This is a special robot system which is practically used in a nuclear fusion device in China. Its design, mechanism and error prediction strategy have great reference values to the similar robots in vacuum and temperature applications.
分类： 核科学技术 >> 核聚变工程技术 提交时间： 2017-10-27
摘要： Structured Abstract: Purpose: EAST is a tokamak fusion device running in ultra-high vacuum condition. To avoid polluting the inner vessel environment, solid lubrication has been applied on the surface of bearings and gears which exposed to the vacuum. Design/methodology/approach: anti-friction MoS2 coatings penetrating with different atoms have been developed by multi-target magnetron sputtering deposition technique. This paper presents the comparative testing of tribological properties for three kinds of MoS2-based coating layers. Findings: based on the test results, MoS2-Ti-C coating films are supposed to be the final selection due to the better performance of friction coefficient and lubrication longevity. Originality/value: finally, the detailed information has been characterized for the hybrid coatings which can provide some references for applications of solid lubrications in similar condition of high vacuum and temperature.
分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2017-08-23
摘要：钨基材料以其高熔点、高导热率、良好的抗中子辐照和抗溅射腐蚀等优异性能，被视为未来核聚变装置中最有前景的面向等离子材料。在聚变服役环境下，14MeV的高能中子以及低能氢/氦粒子流对钨基材料造成严重的辐照损伤。研究材料的辐照损伤与氢氦效应机理对揭示辐照引起材料微观结构与性能的变化以及探索开发新型抗辐照材料具有重要的意义。近年来，随着计算模拟技术的发展，多尺度模拟方法在聚变堆关键材料辐照损伤与氢氦效应机理研究方面有着广泛的应用。本文主要结合作者近几年的研究实践，介绍了纳米晶钨/铁的抗辐照损伤机理、钨中氢滞留机制、合金元素强化界面机制、嬗变元素偏聚及其对氦泡形成机制的影响。通过多尺度模拟方法来获取材料在辐照环境下的不同时间/空间层次的结构演化信息，从而揭示材料的辐照损伤与氢氦效应机理，为聚变堆面向等离子体材料的优化设计与性能调控提供理论基础。
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