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Molecular transport under extreme confinement

science China(Physics,Mechanics & Astronomy) 2022年第6期65卷 1-10页

作者： FengChao Wang JianHao Qian JingCun Fan JinChuan Li HengYu Xu HengAn Wu CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsCAS Center for Excellence in Complex System MechanicsUniversity of Science and Technology of ChinaHefei 230027China

Mass transport through the nanoporous medium is ubiquitous in nature and *** the macroscale transport phenomena which have been well understood by the theory of continuum mechanics,the relevant physics and mechanics on the nanoscale transport still remain *** developments in fabrication of slit-like nanocapillaries with precise dimensions and atomically smooth surfaces have promoted the fundamental research on the molecular transport under extreme *** this review,we summarized the contemporary progress in the study of confined molecular transport of water,ions and gases,based on both experiments and molecular dynamics *** liquid exhibits a pronounced layered structure that extends over several intermolecular distances from the solid surface,which has a substantial influence on static properties and transport behaviors under *** studies have also shown that those molecular details could provide some new understanding on the century-old classical theory in this field.

关键词： confined mass transport nanocapillary solid-liquid interface confinement effect

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The Influence of Turbulators on the Flow and Heat Transfer Characteristic of Helium-Xenon Mixture Inside the Tight Lattice Rod Bundles

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SSRN 2024年

作者： Wang, Lanxin Shi, Xinhuan Li, Zhongchun Wu, Xiaoli Ding, Shuhua Chen, Wei School of Aeronautics and Astronautics Sichuan University Chengdu610065 China Science and Technology on Reactor System Design Technology Laboratory Chengdu610213 China

The gas-cooled nuclear reactor combined with the closed Brayton cycle is the ideal choice for future high-power space missions, while the helium-xenon mixture is a suitable working medium for the reactor due to its good compressibility and heat transfer capacity. For further development and application of more lightweight compact reactor, the influence mechanism of turbulator structures with different angle and layout on the heat transfer enhancement of helium-xenon mixture in the sub-channel of gas-cooled nuclear reactor is numerically studied. The results show that, due to the vortex and secondary flow induced by the turbulator, the heat transfer is enhanced effectively, and the Nusselt number is fluctuated periodically. Compare the result with different angle, the heat transfer enhancement by the turbulator with 90°angle is relatively small, and the pressure drop is large. Because of the secondary flow in narrow triangular space induced by turbulator with 45°angle, the mixing between the high and low temperature fluids will effective enhanced, the heat transfer enhancement is more significant. The heat transfer performance and thermal efficiency index of different turbulator layout are summarized and compared, which provides the reference for heat transfer design of gas-cooled nuclear reactor. © 2024, The Authors. All rights reserved.

关键词： Helium

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BDGSE: A Symbolic Execution Technique for High MC/DC 23

BDGSE: A Symbolic Execution Technique for High MC/DC

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23rd IEEE International Conference on Software Quality, Reliability, and Security, QRS 2023

作者： Cai, Huangli Zhang, Zhiyi Jian, Yifan Li, Dan Huang, Zhiqiu Nanjing University of Aeronautics and Astronautics Collage of Computer Science and Technology Nanjing China Collaborative Innovation Center of Novel Software Technology and Industrialization Nanjing China Nuclear Power Institute of China Science and Technology on Reactor System Design Technology Laboratory Chengdu China Nanjing University of Aeronautics and Astronautics Ministry Key Laboratory for Safety-Critical Software Development and Verification Nanjing China

ISBN: (纸本)9798350319583

Modified Condition/Decision Coverage (MC/DC) is a test coverage standard with excellent fault detection capability, which is widely used in testing safety-critical software. Symbolic execution generates test cases automatically to achieve high code coverage. However, since symbolic execution uses short-circuit evaluation to evaluate decisions, it fails to guarantee the consistency of other conditions in a decision required by the MC/DC criterion. As a result, it is incapable of generating MC/DC test cases to test safety-critical systems adequately. To solve this problem, we propose Branch Dependence Guided Symbolic Execution (BDGSE), a symbolic execution technique for high MC/DC. The approach utilizes static analysis to compute the branch dependencies, then guides symbolic execution to selectively explore paths and simplify test cases, and finally generates a small number of test cases to achieve high MC/DC coverage. Our experimental results show that BDGSE can generate high-quality test cases. Although BDGSE generates fewer test cases, it can achieve higher MC/DC coverage than SPF and random methods, and the fault detection capability of test cases generated by BDGSE is comparable to that of test cases generated by SPF. © 2023 IEEE.

关键词： Software testing

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An Interpretable Dynamic Feature Search Methodology for Accelerating Computational Process of Control Rod Descent in Nuclear reactors

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SSRN 2023年

作者： Huang, Qingyu Xiao, Cong Pang, Zhixin Lin, Yuanfeng Liu, Jia Zhang, Zhuo Zhao, Mengwei Liu, Xiaobo Wang, Yuanmei Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

Within the operational dynamics of a nuclear reactor, the customary approach involves modulating the reactor's power output by means of control rod manipulation, which effectively alters the neutron density across the core. The descent behavior of the control rod drive lines pertains to the intricate motion exhibited by the control rod components within the reactor during its operational lifespan, characterized by conditions of heightened irradiation, temperature, pressure, and complex fluid dynamics. The precise calculation of the control rod descent process is an integral facet of reactor structural design to ensure the safe and reliable operation of the reactor. However, the current computational fluid dynamics-based simulation methods employed for this purpose necessitate extensive grid computations, imposing significant computational burdens in terms of resources and time. In light of this challenge, we present a novel and interpretative algorithm rooted in dynamic similarity feature search. Through comprehensive validation, this algorithm demonstrates remarkable precision with computational results exhibiting an error margin within 10%, while simultaneously achieving a substantial enhancement in computational efficiency of nearly three orders of magnitude when compared to conventional computational fluid dynamics techniques. Notably, this algorithm showcases exceptional versatility, holding immense promise for broad applicability across various operational scenarios encountered during the intricate process of nuclear reactor design. © 2023, The Authors. All rights reserved.

关键词： Control rods

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Experimental Research about Corrosion Effect on Boiling Heat Transfer Performance of Plate-type Samples with Micro-structures 20

Experimental Research about Corrosion Effect on Boiling Heat...

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20th International Topical Meeting on Nuclear reactor Thermal Hydraulics, NURETH 2023

作者： Xu, Wei Liu, Xiaojing Ouyang, Kun He, Xiaoqiang College of Smart Engineering Shanghai Jiao Tong University Shanghai200240 China School of Nuclear Science and Engineering Shanghai Jiao Tong University Shanghai200240 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

ISBN: (纸本)9780894487934

Enormous studies have demonstrated that suitable modification methods, such as micro-structures machining, are adopted to enhance boiling heat transfer performance, especially critical heat flux (CHF) value. This significant improvement can lead to broader application prospect of micro-structured surface in the nuclear power plant scenario. However, little attention has been paid to research the durability of micro-structured surface, and whether strengthening effect can be maintained after a long time of harsh corrosive environment within reactor. In this paper, experimental studies are conducted to research the corrosion effect on boiling heat transfer capability of heating plates with micro-structures. To be specific, microgrooves, pores and columns are machined on metal plate-type samples by laser processing. These samples are placed in autoclave of high temperature and high pressure to simulate the actual conditions, with the corrosion span up to 300 days. After then, saturated pool boiling tests are carried out and high-speed camera is also utilized to quantitatively illustrate the boiling heat transfer characteristics. The experimental results show that the CHF values of different micro-structured samples increase initially and then decreases with increasing corrosion time. In addition, the samples with micro-pores have the largest bubble departure frequency at the beginning of nucleate boiling and those with micro-grooves have the highest CHF value instead. © 2023 Proceedings of the 20th International Topical Meeting on Nuclear reactor Thermal Hydraulics, NURETH 2023. All rights reserved.

关键词： High speed cameras

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A Monte Carlo Code Developed for Radiation Shielding Calculations Based on RMC 23rd

A Monte Carlo Code Developed for Radiation Shielding Calcula...

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23rd Pacific Basin Nuclear Conference, PBNC 2022

作者： Ying, Dongchuan Lyu, Huanwen Tang, Songqian Shang, Xiaotong Xiao, Feng National Key Laboratory of Reactor System Design Technology Nuclear Power Institute of China Chengdu610041 China Department of Engineering Physics Tsinghua University Beijing100084 China

ISBN: (纸本)9789811988981

In this paper, a new developed Monte Carlo method code, intended to be used in shielding calculations, will be introduced. This code was developed on the basis of RMC and under the collaboration of the Nuclear Power Institute of China and Tsinghua University. To meet the requirement of shielding calculations, many features or functions have been realized, such as the flexible fixed source definition and calculation, the gamma transport function, variance reduction function and various tally functions, etc. Those functions have enabled the new version of RMC to have the radiation shielding capability. The validation and application of radiation shielding calculation capability have been carried out. The results of a nuclear power plant pressurized water reactor model will be presented and good agreements have been achieved, which proves the capability of the RMC in the shielding calculations. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Pressurized water reactors

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A Transient Model of Sodium Heat Pipe With Phase Change Temperature Difference 29

A Transient Model of Sodium Heat Pipe With Phase Change Temp...

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2022 29th International Conference on Nuclear Engineering, ICONE 2022

作者： Ruicheng, Zhong Yugao, Ma Qingzhu, Zhao Jang, Deng Yu, Liu Ding, Shuhua Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China College of Letters & Science University of California Santa BarbaraCA93106 United States

ISBN: (纸本)9780791886502

The heat pipe is the essential component in the heat pipe cooled reactor, it conducts heat through the phase change of the working medium and the circulating flow of gas and liquid. One end of the heat pipe is inserted into the reactor as the evaporation section, while the other end serves as the condensation section connecting to the thermoelectric conversion system. Its heat transfer capacity and temperature distribution under a steady state affect the safety, core temperature and energy conversion efficiency of the heat pipe cooled reactor system. Predicting the heat transfer process and steady-state temperature distribution of the heat pipe is helpful to learn about the heat transfer mechanism inside the heat pipe and key factors affecting its performance. It is also helpful to predict the operating characteristics of the heat pipe cooled reactor system and improve the performance of the heat pipe. The heat pipe is generally considered to be a heat transfer element with good isothermal properties. Past studies, however, proved the significant quantity of its phase-change thermal resistance, resulting in a temperature difference at the gas-liquid interface of the heat pipe that affects the evaporation and condensation. Studies on the relationship between the temperature difference, the working temperature, and heat transfer power of the heat pipe are conductive to building a heat pipe model, to predict the temperature distribution of the heat pipe in a steady state in a much more accurate manner. This paper offered a heat pipe model that applies the temperature difference of the phase change interface to calculate the evaporation and condensation. Meanwhile, a 1-meter-long sodium heat pipe was adopted to carry out steady-state heat transfer experiments. Measured and computed the temperature difference of the phase change interface of the heat pipe under varying power and temperature and conducted the relational equation as the input of the heat pipe model. The mo

关键词： Heat pipes

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Dynamic response of the cell traction force to osmotic shock

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Microsystems & Nanoengineering 2023年第5期9卷 321-331页

作者： Yongman Liu Wenjie Wu Shuo Feng Ye Chen Xiaoping Wu Qingchuan Zhang Shangquan Wu School of Biomedical Engineering Anhui Medical University230032 HefeiChina CAS Key Laboratory of Mechanical Behavior and Design of Material Department of Modern MechanicsCAS Center for Excellence in Complex System MechanicsUniversity of Science and Technology of China230026 HefeiChina

Osmotic pressure is vital to many physiological activities,such as cell proliferation,wound healing and disease ***,how cells interact with the extracellular matrix(ECM)when subjected to osmotic shock remains ***,we visualize the mechanical interactions between cells and the ECM during osmotic shock by quantifying the dynamic evolution of the cell traction *** show that both hypertonic and hypotonic shocks induce continuous and large changes in cell traction ***,the traction force varies with cell volume:the traction force increases as cells shrink and decreases as cells ***,the direction of the traction force is independent of cell volume changes and is always toward the center of the cell-substrate ***,we reveal a mechanical mechanism in which the change in cortical tension caused by osmotic shock leads to the variation in traction force,which suggests a simple method for measuring changes in cell cortical *** findings provide new insights into the mechanical force response of cells to the external environment and may provide a deeper understanding of how the ECM regulates cell structure and function.

关键词： traction healing wound

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Molecular levers enable anomalously enhanced strength and toughness of cellulose nanocrystal at cryogenic temperature

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Nano Research 2023年第5期16卷 8036-8041页

作者： YuanZhen Hou Jun Xia ZeZhou He YinBo Zhu HengAn Wu CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsCAS Center for Excellence in Complex System MechanicsUniversity of Science and Technology of ChinaHefei 230027China Faculty of Civil Engineering and Mechanics Jiangsu UniversityZhenjiang 212013China

The quest for widespread applications especially in extreme environments accentuates the necessity to design materials with robust mechanical and thermodynamic *** all existing materials yield temperature-variant mechanical properties,essentially determined by their different atomic bonding *** general,weak non-covalent interactions are considered to diminish the structural anti-destabilization of covalent crystals despite the toughening ***,starting from multiscale theoretical modeling,we herein reveal an anomalous stabilizing effect in cellulose nanocrystals(CNCs)by the cooperation between the non-covalent hydrogen bonds and covalent glucosidic skeleton,namely molecular levers(MLs).It is surprising to find that the hydrogen bonds in MLs behave like covalent bindings under cryogenic conditions,which provide anomalously enhanced strength and toughness for *** analyses demonstrate that the unique dynamical mechanical behaviors from ambient to deep cryogenic temperatures are synergetic results of the intrinsic temperature dependence veiled in MLs and the overall thermo-induced CNC destabilization/*** the consequence,the variation trend of mechanical strength exhibits a bilinear temperature dependence with~77 K as the turning *** underlying investigations not only establish the bottom–up interrelations from the hydrogen bonding thermodynamics to the crystal-scale mechanical properties,but also facilitate the potential application of cellulose-based materials at extremely low temperatures such as those in outer space.

关键词： cellulose nanocrystal molecular lever thermodynamic stability thermo-mechanical behavior cryogenic temperature

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Cybersecurity Risk Assessment of Nuclear Svdu Based on Attack Tree

SSRN

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SSRN 2025年

作者： Wu, Yanqun Wang, Junfeng Ma, Quan Liu, Mingxing Chen, Meiyuan College of Computer Science Sichuan University Chengdu610065 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610000 China

The nuclear power SVDU in nuclear power plants is an important component of the nuclear reactor protection system. With the complete digitalization of the reactor protection system, the risks of cybersecurity attacks have significantly increased. This paper proposes a safety risk assessment method based on an attack tree model to analyze the risk status of the nuclear power SVDU and assess its risk level and security level. Firstly, the typical information security threats faced by nuclear power SVDU are analyzed. Subsequently, an attack tree model of the system is constructed based on the STRIDE model, with four security attributes assigned to the leaf nodes of the tree with reference to the CVSS4.0 system and multi-attribute utility theory. These attributes are quantified through level scoring, and the risk probability of the leaf nodes is calculated using entropy weighting. The risk probability of the root node is then obtained based on the dependency relationship between nodes. Finally, the security risk rating of nuclear power SVDU is obtained. Experimental results demonstrate that the method in this paper more accurately identifies high-risk security threats, predicts possible attack paths, and provides a basis for security protection strategy selection. © 2025, The Authors. All rights reserved.

关键词： reactor shielding

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