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Flexible liquid metal electromagnetic shielding materials

science China(Technological sciences) 2023年第10期66卷 2757-2774页

作者： BAI YunLong ZHANG Jie ZHANG MingKuan RAO Wei Key Laboratory of Cryogenics Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China Beijing Key Lab of CryoBiomedical Engineering and Key Lab of Cryogenics Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100039China School of Future Technology University of Chinese Academy of SciencesBeijing 100049China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical EngineeringTianjin University of TechnologyTianjin 300384China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of TechnologyTianjin 300384China

The demand for flexible shielding has been rapidly growing in recent *** materials using solid metals,carbon materials,or MXenes as shielding units usually have difficulty in combining high shielding and flexibility(stretching and bending characteristics),and thus they gradually fail to meet the shielding needs of flexible ***,shielding materials with both flexibility and high conductivity are urgent to fill this ***-based room temperature liquid metal(LM)is an emerging functional material with a low melting point,low viscosity,low modulus,and easy ***,due to wettability and compatibility issues,it is difficult to apply bulk LMs directly in the field of electromagnetic shielding(EMS).The article reviews the fabrication methods,performance,and applications of LMs EMS materials from three perspectives:Macroscopic LMs,micro/nano-LMs,and LM-based *** gallium-based liquid EMS materials demonstrate the characteristics of high shielding performance with stretchability and a wide shielding *** this review,different types of gallium-based LM materials are described from macroscopic to microscopic,from liquid to semi-solid,from high density to low density,from room temperature to ultra-low temperature,and from monolayer structure to multilayer *** prospect of LM materials as amorphous high-performance EMS materials is demonstrated in various applications,such as mobile communication,astronomical observation,radar,and medical detection,showing tremendous potential in the EMS field.

关键词： liquid metal electromagnetic shielding flexibility

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Direct Numerical Simulation of Turbulent Flow and Heat Transfer in a Rectangular Duct with High Aspect Ratio

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SSRN 2023年

作者： Sun, Yumeng Li, Jie Wei, Zonglan Ai, Zhelun Miao, Heng Deng, Jian Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen University Guangdong Zhuhai519082 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Sichuan Chengdu610213 China

Plate-type fuel is widely used due to its strong heat transfer capability, and its narrow rectangular geometry has different effects on flow heat transfer than traditional rectangular channels. Therefore, in this work, In this work, Direct Numerical Simulation(DNS) of a narrow rectangular duct was performed with the aim of analyzing flow and heat transfer phenomena and constructing a database of turbulent flow. The open-source program Nek5000 based on the spectral element method is used, the geometry is 0.57×0.00367×0.05 m with a high Aspect Ratio(AR) of 13.6, and the bulk Reynolds number is 24000 with a heat flux of 560 kW/m2. Common turbulence statistics like the time mean field, reynolds stress, turbulent heat flux distribution profile, and turbulent kinetic energy budget are obtained. The distribution of Reynolds stress and turbulent kinetic energy budget was analyzed, and the impact of high aspect ratio and material properties on flow and heat transfer was investigated. Additionally, the effects of single-sided and double-sided heating were studied. The turbulent flow database obtained from this study will be utilized for the later evaluation of turbulence models. © 2023, The Authors. All rights reserved.

关键词： Direct numerical simulation

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Experimental Investigation of Droplet Transient Behavior During Reflood Cooling Process of Single-Rod Channel

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SSRN 2023年

作者： Chen, Mingjing Chen, Deqi Liu, Haiong Liu, Hanzhou Zhong, Lei Deng, Jian Key Laboratory of Low-grade Energy Utilization Technologies and Systems Chongqing University Ministry of Education Chongqing400044 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China

The reflood process after a loss of coolant accident (LOCA) in a nuclear reactor involves complex two-phase flow with low pressure and flow rate, as well as boiling phase transition. Accurately predicting the transient behavior of liquid droplets during the dispersed flow stage is crucial for evaluating reactor accidents, including peak cladding temperature (PCT). However, existing prediction models for liquid droplets in dispersed flows are typically based on quasi steady-state annular flow models and do not account for transient behavior, such as the propulsion characteristics of the quench front during strong transient flooding processes, and the formation mechanism of large droplets. In this study, we present the results of a visualization experiment of reflood cooling in a single-rod channel to investigate the development mechanisms of droplet formation and fragmentation. We observe the evolution behavior of the vapor-liquid interface during the reflood process and quantitatively analyze the transient size distribution characteristics of the droplets. Based on these findings, the transient characteristics of the quench front propagation during reflood, Kelvin-Helmholtz (K-H) instability, hot wall ejection mechanisms for droplet formation, and aerodynamic and capillary breakup mechanisms for droplet breakage, as well as entrainment and evaporation of droplets under high-speed steam are considered. A prediction model for droplet transient behavior during single-rod channel reflood cooling is established, and the results are compared with experimental data. © 2023, The Authors. All rights reserved.

关键词： Cooling

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Understanding Xenon and Vacancy Behaviors in Uo2, Un and U3si2: A Comparative Ab Initio Study

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SSRN 2022年

作者： Zhao, Jiajun Sun, Dan Wang, Yuanyuan Xi, Liu Chen, Ping Zhao, Jijun Dalian University of Technology Liaoning Dalian China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Sichuan Chengdu China

Extensive attention has been paid to accident tolerant fuels (ATFs), such as uranium mononitride (UN) and uranium sesquisilicide (U3Si2), which are regarded as the potential candidates to replace uranium dioxide (UO2) in light water reactor (LWR). However, the thermodynamic behavior of fission gas atom in these fuels that can quantitatively affect the burnup characteristics of ATF needs to be explored. To this end, the systematic ab initio investigation on the energetic properties of xenon (Xe)-vacancy complexes in UO2, UN and U3Si2 is performed with the GGA+U approach as well as the corrected chemical potential. The stabilities of Xe-vacancy clusters, including interstitial trap site (IS), mono-, bi- and tri-atomic vacancy, are thoroughly assessed. The formation energies of vacancy complexes indicate that it is more likely to form vacancy cluster defects and their complexes with Xe in UO2 and to generate mono-atomic vacancy and Xe-vacancy complex in both UN and U3Si2. Xe can be strictly confined by the trap sites in UO2 and UN, and yet in U3Si2, it prefers to move to the centre of a large free volume trap site. The strongest soluble characteristic of Xe in U3Si2 indicates excellent storage compacity of fission gas products in the matrix. This work can provide comprehensive insights into the original reason of interplay between Xe and vacancy as well as the thermodynamic behavior of those defects in the uranium-based fuels. © 2022, The Authors. All rights reserved.

关键词： Uranium dioxide

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Magnitude,distribution and temporal trend of nitrous oxide emissions from China's natural soils over 1980–2022

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science China Earth sciences 2025年第4期68卷 1074-1085页

作者： Songbai HONG Zimeng LI Mingsong TANG Fa LI Yitong YAO Yanzi YAN Mingzhu HE Xuhui WANG Hui ZENG Shilong PIAO School of Urban Planning and Design Shenzhen Graduate SchoolPeking UniversityShenzhen518055China Key Laboratory of Earth Surface System and Human-Earth Relations Ministry of Natural Resources of ChinaShenzhen Graduate SchoolPeking UniversityShenzhen518055China Institute of Carbon Neutrality Sino-French Institute for Earth System ScienceCollege of Urban and Environmental SciencesPeking UniversityBeijing100871China Department of Earth System Science Stanford UniversityStanfordCA94305USA Division of Geological and Planetary Sciences California Institute of TechnologyPasadenaCA91125USA Department of Soil and Environment Swedish University of Agricultural SciencesUppsala75007Sweden Joint International Research Laboratory of Catastrophe Simulation and Systemic Risk Governance Beijing Normal UniversityZhuhai519087China School of National Safety and Emergency Management Beijing Normal UniversityZhuhai519807China

Soils represent the largest contributor to global nitrous oxide(N_(2)O)***,current research efforts predominantly focus on N_(2)O emissions from agricultural soils,while studies on N_(2)O emissions from natural soils,another significant source,remain *** this study,we explored the magnitude,spatiotemporal dynamics,and drivers of N_(2)O emissions from China's natural soils over the period 1980–2022 via machine learning and a compiled novel dataset of 319 field *** results revealed that the N_(2)O flux per unit area was generally higher in the southeast compared to the northwest,and higher in forests than in *** spatial and biome heterogeneity was strongly regulated by local hydrothermal conditions and nitrogen *** averaged N_(2)O emissions over the study period were 646.2±27 Gg N_(2)O yr^(-1),with approximately equivalent contributions from forests and ***,there exhibited a significant and increasing trend from 1980 to 2022,with a rate of 2.7 Gg N_(2)O yr^(-2).Such an increase was primarily driven by the expansion of forested area and elevated nitrogen *** data-driven study presents a long-term and gridded estimate of N_(2)O emissions from China's natural soils,emphasizing the need for future research on changes of greenhouse gas emissions induced by land use change and nitrogen deposition.

关键词： Nitrous oxide Spatiotemporal dynamics Nitrogen deposition Forests Grasslands Data-driven estimates

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Assessment of Coupled Effect of Steam Pipes on Seismic Analysis of reactor Coolant system

Assessment of Coupled Effect of Steam Pipes on Seismic Analy...

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作者： Lijuan Li Zhenyu Liu Hui Li Xianhui Ye Honglei Ai National Key Laboratory of Science and Technology on Reactor System Design Technology

reactor coolant system is connected with auxiliary pipes, surge pipes and steam pipes. In order to facilitate the dynamic analysis of reactor coolant system, it is necessary to decouple the pipes connected with the reactor coolant system. Although some international standards stipulating requirements for the decoupling of subsystems from the main system, in order to further explore the influence of decoupling steam pipes, the seismic response of reactor coolant system with or without steam pipes is simulated by using ANSYS program. Firstly, the modal analysis of reactor coolant system is carried out to analysis the influence of steam pipes on the resonant frequency of reactor system. Then, the standardized seismic dynamic analysis of reactor system with or without steam pipes is carried out. The nozzle load(inlet and outlet nozzle load of main device, such as reactor pressure vessel, steam generator, pump) and support load(of main device such as reactor pressure vessel, steam generator, pump) are output and compared. According to nozzle load and support load, it can be seen that the steam pipes have little influence on the seismic analysis of reactor coolant system, i.e. steam pipes can be decoupled in the seismic analysis of reactor coolant system.

关键词： reactor coolant system dynamic analysis seismic response decouple steam pipes

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Analysis of Transient Characteristics of Droplets in the Dffb Regime During Single-Rod Channel Reflood Experiment

SSRN

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SSRN 2023年

作者： Chen, Deqi Chen, Mingjing Liu, Hanzhou Liu, Haidong Zhong, Lei Deng, Jian Key Laboratory of Low-grade Energy Utilization Technologies and Systems Chongqing University Ministry of Education Chongqing400044 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China

This study aims to explore the dynamic distribution and hydrodynamic characteristics of droplets in the process of strong transient reflood. However, the quasi-steady state analysis is generally adopted in the current study, ignoring the dependence of droplet formation and breaking mechanism in the Dispersed flow film boiling (DFFB) mechanism on the time-related historical behaviors such as the advance of the quench front. A series of reflood cooling visualization experiments of zirconium alloy high-temperature rod-shaped heating surface were carried out to achieve this research goal. The wall surface and fluid temperature history curves were recorded, and the parameters, such as the size and velocity of DFFB regime droplets, were quantitatively extracted by visual image processing technology. Based on the formation and breakup mechanism of droplets in the dispersed flow, the reasons for droplet size distribution and velocity change with input heat flux, initial wall temperature, inlet subcooling, and inlet flow rate are well analyzed and explained. At the same time, the experimental results also show a strong correlation between droplet behavior and the reflood process in time. This study can provide more detailed physical support for the subsequent development of droplet behavior models more suitable for the strong transient reflood process and the evaluation of existing models. © 2023, The Authors. All rights reserved.

关键词： Heat flux

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Analysis of Transient Characteristics of Droplets in the Dffb Regime During Single-Rod Channel Reflood Experiment

SSRN

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SSRN 2023年

This study aims to explore the dynamic distribution and hydrodynamic characteristics of droplets during the highly transient process of reflood. However, the quasi-steady state analysis is generally adopted in the current study, ignoring the dependence of droplet formation and breaking mechanism in the Dispersed flow film boiling (DFFB) mechanism on the time-related historical behaviors such as the advance of the quench front. A series of reflood cooling visualization experiments of zirconium alloy high-temperature rod-shaped heating surface were carried out to achieve this research goal. The wall surface and fluid temperature history curves were recorded, and the parameters, such as the size and velocity of DFFB regime droplets, were quantitatively extracted by visual image processing technology. Based on the formation and breakup mechanism of droplets in the dispersed flow, the reasons for droplet size distribution and velocity change with input heat flux, initial wall temperature, inlet subcooling, and inlet flow rate are well analyzed and explained. At the same time, the experimental results also show a strong correlation between droplet behavior and the reflood process in time. This study can provide more detailed physical support for the subsequent development of droplet behavior models more suitable for the strong transient reflood process and the evaluation of existing models. © 2023, The Authors. All rights reserved.

关键词： Heat flux

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Dynamic Rod Worth Estimation with Extended Kalman Filter and Background Current Elimination

Dynamic Rod Worth Estimation with Extended Kalman Filter and...

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第40届中国控制会议

作者： Hao Xia Junqi Yang Chao Bao Dalian University of Technology Science and Technology on Reactor System Design Technology Laboratory

The dynamical rod worth method(DRWM) is a fast and accurate method to measure and validate the worth of control rod during the zero power physics test at pressure water nuclear *** control rod worth is obtained from the reactivity change caused by the fast insertion of the control rod into the bottom of the *** reactivity is calculated based the measured ex-core detector signals which normally varies from～10 nA to～10 nA during the rod insertion *** the later stage of the test,as the detector signal becomes～10 nA,the impact of the measurement noise and the gamma-ray background current on the reactivity calculation becomes *** this paper,we developed an extended Kalman filter(EKF) with suitable weighing matrices to filter out the measurement *** most measurement noise filtered out,a background current estimation method is used to eliminate the effect of the background *** combining the background current estimation method with EKF filter,accurate control rod worth is obtained from the real test data.

关键词： Dynamic Rod Worth Method Reactivity Extended Kalman filter Background Current

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Thermal-Mechanical Influence Aspects and Evaluation of Helical Cruciform Single Rod in Fluoride-Salt-Cooled High-Temperature Advanced reactor

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SSRN 2024年

作者： Chen, Yiwen Zhang, Dalin Jiang, Dianqiang Li, Wei Wu, Xiaoli Tian, Wenxi Qiu, Suizheng Su, Guanghui Lu, Qi State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong University Xi’an710049 China Science Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China China

Helical cruciform fuels are novel in nuclear reactors, potential to increase reactor’s power density. However, the geometry is complicated so influence of it on the fuel performance is not identified yet. In this paper, impact of power density, cross-section parameters, and twist pitch on thermal and mechanical characteristics of fuel used in Fluoride-Salt-cooled high-Temperature Advanced reactor is discussed based on fluid-thermal-mechanical coupling. For thermal features, twist pitch is key while others have few effects. Increase in twist pitch leads to temperature uniformity and rise owing to weaker mixing effects. Fuel center temperature at middle plane of 300mm-pitch rod is 829.58℃, 54.66℃ higher than that of 100mm-pitch rod. Difference of maximum and minimum temperature at 45° cross section of 500mm-pitch rod is 153.62℃, while the figure is only 74.00℃ of 300mm-pitch rod. Besides, axial temperature of cladding outer surface increases wavelike due to complex geometry. For mechanical features, not geometry sizes but temperature affects stress distribution. Maximum Von-Mises stress appears at the elbow, where maximum temperature exists, 116.8MPa under normal conditions, lower than tensile strength of the material. After identifying the influence of these factors, five dimensionless parameters are proposed to evaluate and rate fuel performance based on Technique for Order Preference by Similarity to an Ideal Solution. As a result, an optimization comes up, scoring 0.310, twice more than the original design, owing to the thermal uniformity and mechanical safety. This study provides a reference for identifying and evaluating the performance of helical structure. © 2024, The Authors. All rights reserved.

关键词： Geometry

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