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CFD-DEM simulation of fluorination reaction in fluidized beds with local grid and time refinement method

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Particuology 2024年第1期84卷 145-157页

作者： Mofan Qiu Lin Jiang Rongzhen Liu Yaping Tang Malin Liu institute of nuclear and New Energy technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyTsinghua UniversityBeijing100084China

The gas-solid reaction process with wide particle size distribution is extensively used in the chemical engineering field,especially the particle reacts with the gas gradually,such as fluorination reactions in fluidized *** the computational fluid dynamics-discrete element method(CFD-DEM)is used for the coupling simulation of multiphase and polydisperse particle reaction system,the grid size directly affects the accuracy of flow field information and simulation of chemical ***,particle calculation time step will directly affect the efficiency of coupling *** this work,a local grid and time step refinement method is proposed to simulate multiphase and polydisperse particle fluid-ization reaction *** this method,the refined DEM grids are automatically generated in the computational domain around the fine particles,and the detailed fluid phase information is obtained with the interpolation *** the two-phase coupling process,particles are divided into different groups based on physical properties,each group has its own independent time *** multistage conical-cylindrical spouted bed is proposed for the fluorination reaction process;the operating gas ve-locity range of the polydisperse particle system is extended by the new design while the particle size distribution changes with the gas-solid reaction *** is demonstrated that the local grid and time step refinement method can improve the accuracy and efficiency of the traditional CFD-DEM method in the reaction process simulation,which describes a polydisperse particle system with wide particle size *** at improving the simulation accuracy and efficiency,this paper will be helpful for simulating the particle reaction process in the gas-solid fluidized bed and beneficial for the development of the CFD-DEM method.

关键词： CFD-DEM Polydisperse particle Two-phase flow Fluidized bed

Halogen-bond induced unusual polyhalogen anions formation in hydrogen-bonded frameworks to secure iodine sequestration

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Nano Research 2024年第7期17卷 6766-6772页

作者： Yi Xie Pengling Huang Qiang Gao Shiyu Wang Jianchen Wang Gang Ye Collaborative Innovation Center of Advanced nuclear Energy technology Institute of Nuclear and New Energy TechnologyTsinghua UniversityBeijing 100084China

Safe confinement of fission iodine isotopes for long-term radioactive waste disposal remains a formidable challenge,as conventional sorbents provide inherently weak iodine-host *** report here a novel halogen bond(X-bond)directed strategy to sequester volatile iodine in hydrogen-bonded(H-bonded)frameworks with unprecedented ***-assisted Hbonded frameworks bearing open halide sites are developed,showing distinctive iodine encapsulation behaviors without compromising the *** crystallographic evidence indicates the formation of X-bonds,i.e.,I–I···Cl^(−) and I–I···Br^(−),within the confined pore *** polyhalogen anions,i.e.,[I_(2)Cl_(2)]^(2−)and[I_(2)Br_(2)]^(2−),sustained in H-bonded frameworks are identified for the first *** X-bond reinforced host-guest interaction affords robust iodine trapping without leaking out even at elevated temperatures up to 180℃.By integrating the halogen-bond chemistry with H-bonded frameworks,this study offers fresh concepts for developing effective host reservoirs to secure fission iodine isotopes from spent fuel reprocessing off-gases.

关键词： halogen-bond chemistry anion coordination chemistry hydrogen-bonded organic frameworks polyhalogen anions iodine confinement

Perception of fundamental science to boost lithium metal anodes toward practical application

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Green Energy & Environment 2024年第3期9卷 454-472页

作者： Jinkun Wang Li Wang Hong Xu Li Sheng Xiangming He institute of nuclear and New Energy technology Tsinghua UniversityBeijing100084China

As a key material for lithium metal batteries(LMBs),lithium metal is one of the most promising anode materials to break the bottleneck of battery energy density and a commonly used active material for reference *** lithium anodes are regarded as the holy grail of lithium batteries,decades of exploration have not led to the successful commercialization of LMBs,due mainly to the challenges related to the inherent properties of lithium *** pave the way for further investigation,herein,a comprehensive review focusing on the fundamental science of lithium are ***,the natures of lithium atoms and their isotopes,lithium clusters and lithium crystals are revisited,especially their structural and energetic ***,the electrochemical properties of lithium metal are *** important concepts and scientific questions,including the electronic structure of lithium,influence of high pressure and low temperature on the properties of lithium,factors influencing lithium deposition,generation of lithium dendrites,and electrode potential of lithium in different electrolytes,are explained and analyzed in *** to improve the performance of lithium anodes and thoughtfulness about the electrode potential in lithium battery research are proposed.

关键词： Lithium Cluster Crystal Physicochemical property Fundamental science

Electronic effects on radiation damage inα-iron:A molecular dynamics study

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Chinese Physics B 2024年第3期33卷 521-529页

作者：江林李敏付宝勤崔节超侯氢 Key Laboratory for Radiation Physics and technology Institute of Nuclear Science and TechnologySichuan UniversityChengdu 610064China

Iron(Fe)-based alloys,which have been widely used as structural materials in nuclear reactors,can significantly change their microstructure properties and macroscopic properties under high flux neutron irradiation during operation,thus,the problems associated with the safe operation of nuclear reactors have been put forward *** this work,a molecular dynamics simulation approach combined with electronic effects is developed for investigating the primary radiation damage process inα-***,the influence of electronic effects on the collision cascade in Fe is systematically evaluated based on two commonly used interatomic potentials for *** simulation results reveal that both electronic stopping(ES)and electron-phonon coupling(EPC)can contribute to the decrease of the number of defects in the thermal spike *** application of ES reduces the number of residual defects after the cascade evolution,whereas EPC has a reverse *** introduction of electronic effects promotes the formation of the dispersive subcascade:ES significantly changes the geometry of the damaged region in the thermal spike phase,whereas EPC mainly reduces the extent of the damaged ***,the incorporation of electronic effects effectively mitigates discrepancies in simulation outcomes when using different interatomic potentials.

关键词： radiation damage electronic effects molecular dynamics simulation α-iron

First-principles study on the diffusion behavior of Cs and I in Cr coating

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nuclear Science and Techniques 2024年第6期35卷 177-188页

作者： Shu-Ying Lin Xiao-Jing Li Lin-Bing Jiang Xi-Jun Wu Hui-Qin Yin Yu Ma Wen-Guan Liu Sino-French institute of nuclear Engineering and technology Sun Yat-Sen UniversityZhuhai 519082China School of nuclear Science and technology University of South ChinaHengyang 421001China

Cs and I can migrate through fuel-cladding interfaces and accelerate the cladding corrosion process induced by the fuel-cladding chemical *** coating has emerged as an important candidate for mitigating this chemical *** this study,first-principles calculations were employed to investigate the diffusion behavior of Cs and I in the Cr bulk and grain boundaries to reveal the microscopic interaction mitigation mechanisms at the fuel-cladding *** interaction between these two fission products and the Cr coating were studied systematically,and the Cs and I temperature-dependent diffusion coefficients in Cr were obtained using Bocquet’s oversized solute-atom model and Le Claire’s nine-frequency model,*** results showed that the Cs and I migration barriers were significantly lower than that of Cr,and the Cs and I diffusion coefficients were more than three orders of magnitude larger than the Cr self-diffusion coefficient within the temperature range of Generation-IV fast reactors(below 1000 K),demonstrating the strong penetration ability of Cs and ***,Cs and I are more likely to diffuse along the grain boundary because of the generally low migration barriers,indicating that the grain boundary serves as a fast diffusion channel for Cs and I.

关键词： First-principles calculation Fuel cladding chemical interaction Cr coating Fission product Diffusion Grain boundary

High-power compact continuous-wave Fe:ZnSe laser at 4μm with>50%overall conversion efficiency

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Chinese Optics Letters 2024年第8期22卷 87-92页

作者： Yanlong Shen Yingchao Wan Feng Zhu Tongxing Chai Yousheng Wang Ke HuangState Key Laboratory of Laser Interaction with Matter Northwest Institute of Nuclear TechnologyXi’an 710024China

We report on a compact,high-efficiency mid-infrared continuous-wave(CW)Fe:ZnSe laser pumped by a 2.9μm fiber laser under liquid nitrogen cooling.A maximum output power of 5.5 W and a slope efficiency of up to 66.3%with respect to the launched pump power were *** overall optical-to-optical(OTO)conversion efficiency,calculated from the output of the 2.9μm fiber laser to the 4μm laser,was as high as~54.5%.The OTO efficiency and the slope efficiency are,to the best of our knowledge,the highest ever reported in Fe:ZnSe lasers.A rate-equation-based numerical model of CW operation was established,and the simulation agreed well with the experiment,identifying the routes used in the experiment for such high efficiency.

关键词： Fe:ZnSe mid-infrared laser high efficiency solid-state laser

Comparison of thermal shock resistance capabilities of the rotary swaged pure tungsten,potassium-doped tungsten,and W-La2O3 alloys

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Tungsten 2024年第4期6卷 759-766页

作者： Tao Yang Hao Wang Fan Feng Xiang Liu Xue-Yu Gong You-Yun Lian Jian-Bao Wang School of nuclear Science and technology University of South China Southwestern institute of Physics

Tungsten-based materials are one of the most important candidates for the plasma facing materials（PFMs） of future fusion reactors,and it is necessary to study the properties of tungsten-based materials under the service conditions of fusion devices to ensure the long-term steady-state operation of future fusion *** this paper,different tungsten-based materials made by the same rotary swaging process are selected to simulate the transient thermal loads on the PFMs of a fusion reactor using an electron beam,and thermal load experiments are carried out by changing the power density of a loading pulse and the pulse *** is found that different tungsten-based materials made by the same process have large differences in thermal shock resistance,and the doped tungsten materials（W-K and W-La2O3） are significantly better than the pure tungsten materials with the increase in thermal shock power density and the number of cycles,especially the W-K materials,which have excellent performance.

关键词： Electron beam Rotary swaging Thermal shock Tungsten materials

The biochemical behavior and mechanism of uranium(Ⅵ)bioreduction induced by natural Bacillus thuringiensis

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Journal of Environmental Sciences 2024年第2期136卷 372-381页

作者： Shunzhang Chen Junyuan Gong Yanxia Cheng Yuqi Guo Feize Li Tu Lan Yuanyou Yang Jijun Yang Ning Liu Jiali Liao Key Laboratory of Radiation Physics and technology of the Ministry of Education Institute of Nuclear Science and TechnologySichuan UniversityChengdu 610064China

For a broader understanding of uranium migration affected by microorganisms in natural anaerobic environment,the bioreduction of uranium(Ⅵ)(U(Ⅵ))was revealed in Bacillus thuringiensis,a dominant bacterium strain with potential of uranium-tolerant isolated from uranium contaminated *** reduction behavior was systematically investigated by the quantitative analysis of U(Ⅳ)in bacteria,and mechanism was inferred from the pathway of electron *** anaerobic conditions,appropriate biomass and sodium lactate as electron donor,reduction behavior of U(Ⅵ)induced by *** was restricted by the activity of lactate dehydrogenase,which was directly affected by the initial pH,temperature and initial U(Ⅵ)concentration of bioreduction *** of U(Ⅵ)was driven by the generation of nicotinamide adenine dinucleotide(NADH)from enzymatic reaction of sodium lactate with various *** transmission of the electrons from bacteria to U(Ⅵ)was mainly supported by the intracellular NADH dehydrogenase-ubiquinone system,this process could maintain the biological activity of cells.

关键词： Uranium Bacillus thuringiensis Bioreduction Electron transmission

High-resolution neutronics model for ^(238)Pu production in high-flux reactors

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nuclear Science and Techniques 2024年第5期35卷 226-236页

作者： Qing-Quan Pan Qing-Fei Zhao Lian-Jie Wang Bang-Yang Xia Yun Cai Jin-Biao Xiong Xiao-Jing Liu School of nuclear Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Science and technology on Reactor System Design technology Laboratory Nuclear Power Institute of ChinaChengdu 610200China

We proposed and compared three methods(filter burnup,single energy burnup,and burnup extremum analysis)to build a high-resolution neutronics model for 238Pu production in high-flux *** filter burnup and single energy burnup methods have no theoretical approximation and can achieve a spectrum resolution of up to~1 eV,thereby constructing the importance curve and yield curve of the full energy *** burnup extreme analysis method combines the importance and yield curves to consider the influence of irradiation time on production efficiency,thereby constructing extreme *** three curves,which quantify the transmutation rate of the nuclei in each energy region,are of physical significance because they have similar distributions.A high-resolution neutronics model for ^(238)Pu production was established based on these three curves,and its universality and feasibility were *** neutronics model can guide the neutron spectrum optimization and improve the yield of ^(238)Pu by up to 18.81%.The neutronics model revealed the law of nuclei transmutation in all energy regions with high spectrum resolution,thus providing theoretical support for high-flux reactor design and irradiation production of ^(238)Pu.

关键词： ^(238)Pu Neutronics model High-flux reactor Spectrum resolution Spectrum optimization