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2020 International Conference on Nuclear Engineering, ICONE 2020, collocated with the ASME 2020 Power Conference

作者： Ma, Yugao Liu, Minyun Han, Wenbin Xie, Biheng Chai, Xiaoming Huang, Shanfang Yu, Hongxing Department of Engineering Physics Tsinghua University Beijing China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

ISBN: (纸本)9780791883785

Space fission power systems can enable ambitious solarsystem and deep-space science missions. The heat pipe cooled reactor is one of the most potential candidates for near-term space power supply, featured with safety, simplicity, reliability, and modularity. Heat pipe cooled reactors are solid-state and high temperature (up to 1500 K) reactors, where the thermal expansion is remarkable and the mechanical response significantly influences the neutronics and thermal analyses. Due to the considerable difference between heat pipe cooled reactors and traditional water reactors in the structure and design concept, the coupling solutions for light water reactors cannot be directly applied to heat pipe cooled reactor analyses. Therefore, new coupling framework and program need to consider the coupling effects among neutronics, heat transfer as well as mechanics. Based on the Monte Carlo program RMC and commercial finite element program ANSYS Mechanical APDL, this work introduces the three coupling fields of neutronics (N), thermal (T), and mechanics (M) for heat pipe cooled reactors. The neutronic and thermal-mechanical (N/T-M) coupling strategy is developed theoretically, focusing on the formulation of the nonlinear problem, iteration schemes, and relaxation methods. Besides, the finite element method and the Monte Carlo program use different meshes and geometry construction methods. The spatial mapping and geometry reconstruction are also essential for the N/T-M coupling, which is discussed and established in detail. Furthermore, the N/T-M coupling methods are applied to the preliminary self-designed 10 kWe space heat pipe cooled reactor. Coupling shows that the thermal-mechanical feedback in the solid-state reactor has negative reactivity feedback (-2007 pcm) while it has a deterioration in heat transfer due to the expansion in the gas gap. © 2020 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Heat pipes

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Experimental investigation on temperature characteristics of direct contact condensation in a natural circulation system

Experimental investigation on temperature characteristics of...

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2020 International Conference on Nuclear Engineering, ICONE 2020, collocated with the ASME 2020 Power Conference

作者： Sun, Jianchuang Ding, Ming Mi, Zhengpeng Zhang, Zhuohua Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Harbin Engineering University Harbin China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

ISBN: (纸本)9780791883785

Direct contact condensation (DCC) is a common physical phenomenon appearing in the nuclear power plants and other industrial applications. The current research on DCC focuses on steam-water counterflow or jet flow under forced flow conditions. For some natural-circulation passive safety systems in floating nuclear power plants, the heated section is connected with the heat sink by the horizontal pipes. The heat sink is usually the ocean. In such natural circulation systems (NCSs), the steam produced in the heated section will inevitably contact the subcooled water in the ocean and result in DCC event. In this paper, the fundamental characteristics of two-phase flow were described in detail. In addition, the influences of the subcooled water temperature on the flow rate, outlet temperature, steam bubble behaviors, and pressure surge were emphatically discussed. The experimental results revealed that the subcooled water in the water tank could reversely flow into the pipe, which was able to cause condensation induced water hammer (CIWH) event and flow oscillation. Further research showed that the subcooled water was evidently prevented from reversely flowing into the pipe with the increase in the subcooled water temperature. The position where the DCC event occurs transferred from the pipe to the water tank, and the pressure peak obviously reduced, even disappear when the subcooled water temperature is larger than 61 oC. © 2020 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Water temperature

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Study on Imc-Pid Control of Once Through Steam Generator for Small Lead Bismuth Fast reactor

SSRN

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SSRN 2022年

作者： Sun, Aodi Zhang, Ru Xiao, Kai He, Zhengxi Sun, Peiwei Wei, Xinyu Key Laboratory of Advanced Nuclear Energy and Technology Shaanxi Engineering Research Center of Advanced Nuclear Energy Xi’an Jiaotong University Xi’an710049 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

Due to the particularity of nuclear reactor, it is difficult to adjust the controller parameters by experiment. The simulation calculation inevitably simplifies the actual model. The controller parameters tuned by this model is likely to cause poor performance due to model mismatch. Therefore, the research on the adaptability of the controller to model mismatch has guiding significance for engineering application. In this paper, a once through steam generator(OTSG) for small lead bismuth fast reactor(SLBFR) is established and verified, and the presented model is simplified by three different methods. Internal model control(IMC) and IMC-PID controllers are designed based on the simplified models. With the increase of λ , IMC-PID controller becomes insensitive to model mismatch caused by model linearization, non-minimum phase characteristics, noise and time delay, and has high robustness to model mismatch. However, the robustness to model sacrifices the sensitivity of the system. In the study of rapid power reduction, it is found that large λ will lead to conservative control output, and then make the control performance worse. Through the research of this paper, Method 1 is recommended, and λ is selected between 5 and 10 to design feedwater IMC-PID controller for OTSG of SLBFR. © 2022, The Authors. All rights reserved.

关键词： Model predictive control

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Experimental Study on Surface Characteristics and Thermal Conductivity of New Zirconium Alloy with Oxide Layer

SSRN

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SSRN 2022年

作者： Zhong, Lei Chen, Deqi Yu, Hongxing Liu, Haidong Chen, Mingjing Liu, Hanzhou Deng, Jian Ding, Shuhua Wu, Dan Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China Key Laboratory of Low-grade Energy Utilization Technologies and Systems Chongqing University Ministry of Education Chongqing 400044 China

The surface properties and thermal conductivity of oxide layer formed on the new zirconium alloy due to high temperature steam oxidation are studied in this paper. The thickness of oxide layer, surface wettability and thermal conductivity are measured. The effects of oxidation temperature and time on the wettability and thermal conductivity of zirconium alloy are analyzed. The results show that zirconium on the surface is fully oxidized to ZrO2 , and the difference of surface wettability is caused by different surface morphology. The characteristics of oxide layer surface cracks will affect the surface wettability. At the same oxidation temperature, with increasing time duration, the size and number of oxide layer cracks increase. The change of thermal conductivity is the result of competition among factors such as the development of recrystallization process, the increase of oxide layer thickness and the influence of pores and cracks. © 2022, The Authors. All rights reserved.

关键词： Wetting

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Evolutionary Morphology Towards Overconstrained Locomotion via Large-Scale, Multi-Terrain Deep Reinforcement Learning

Evolutionary Morphology Towards Overconstrained Locomotion v...

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ASME/IFToMM International Conference on Reconfigurable Mechanisms and Robots, ReMAR

作者： Yenan Chen Chuye Zhang Pengxi Gu Jianuo Qiu Jiayi Yin Nuofan Qiu Guojing Huang Bangchao Huang Zishang Zhang Hui Deng Wei Zhang Fang Wan Chaoyang Song Department of Mechanical and Energy Engineering Southern University of Science and Technology (SUSTech) Shenzhen China SUSTech School of Design Department of System Design and Intelligent Manufacturing SUSTech. Shenzhen Key Lab of Intelligent Robotics & Flexible Manufacturing Systems SUSTech. SUSTech. SUSTech Institute of Robotics

ISBN: (数字)9798350395969

ISBN: (纸本)9798350395976

While the animals' Fin-to-Limb evolution has been well-researched in biology, such morphological transformation remains under-adopted in the modern design of advanced robotic limbs. This paper investigates a novel class of overconstrained locomotion from a design and learning perspective inspired by evolutionary morphology, aiming to integrate the concept of ‘intelligent design under constraints’–hereafter referred to as constraint-driven design intelligence–in developing modern robotic limbs with superior energy efficiency. We propose a 3D-printable design of robotic limbs parametrically reconfigurable as a classical planar 4-bar linkage, an overconstrained Bennett linkage, and a spherical 4- bar linkage. These limbs adopt a co-axial actuation, identical to the modern legged robot platforms, with the added capability of upgrading into a wheel-legged system. Then, we implemented a large-scale, multi-terrain deep reinforcement learning framework to train these reconfigurable limbs for a comparative analysis of overconstrained locomotion in energy efficiency. Results show that the overconstrained limbs exhibit more efficient locomotion than planar limbs during forward and sideways walking over different terrains, including floors, slopes, and stairs, with or without random noises, by saving at least 22% mechanical energy in completing the traverse task, with the spherical limbs being the least efficient. It also achieves the highest average speed of 0.85m/s on flat terrain, which is 20% faster than the planar limbs. This study paves the path for an exciting direction for future research in overconstrained robotics leveraging evolutionary morphology and reconfigurable mechanism intelligence when combined with state-of-the-art methods in deep reinforcement learning.

关键词： Couplings Legged locomotion Technological innovation Education Noise Morphology Stairs

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Development of the Expanding Mandrel Test Facility for Investigation of Zircaloy Cladding Performance Under Loading Strain Rate Similar to Power Ramp

SSRN

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SSRN 2022年

作者： He, Yanan Wu, Yingwei Qiu, Bowen Lei, Zhao He, Liang Jiao, Yongjun Chen, Ping Tian, Wenxi Su, Guanghui Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology Shaanxi Engineering Research Center of Advanced Nuclear Energy Xi’an Jiaotong University Xi'An710049 China Nuclear Power Institute of China Science and Technology on Reactor System Design Technology Laboratory Chengdu China

The in-pile pellet-cladding interaction (PCI) is the one of challenging problems for conventional UO2-Zicaloy fuel systems, which can threaten the integrity of the fuel rod and lead to the release of fission product. Currently, several experiments and numerical studies have been devoted to PCI analysis. However, attributing the lacking of experimental data with high fidelity, the development, and validation of the PCI analysis model is not sufficient. In this study, an expanding mandrel test facility has been developed to investigate PCI behaviors, where the digital image correlation (DIC) measuring system was introduced to online monitor the displacements/strain of cladding outer surface with improved fidelity. In addition, the oxygen content measurement system was employed to identify the failure of cladding. Subsequently, the expanding mandrel test facility was leveraged to investigate the PCI performance of three types of cladding (e.g. N36 cladding, recrystallized Zircaloy4 cladding, and M5 cladding) under both with/without iodine corrosion and cladding real-time strain, failure time and failure strain were recorded. Then, performance comparisons among these claddings were completed and discussed. The results show that the established facility can be applied to expanding mandrel tests under varied theoretical loading strain rates (10~60%/h) and the working environment temperature can reach 350 . Meanwhile, there are three distinct stages for the deformed Zicaloy cladding during the expanding mandrel test. The comparison results suggest that recrystallized Zircaloy4 cladding shows the largest cladding failure strain with/without iodine corrosion under 20%/h theoretical loading strain, while M5 cladding and N36 cladding present considerable performance without iodine corrosion effect. In addition, N36 and recrystallized Zircaloy4 cladding seems more iodine corrosion resistant than that for M5 cladding, which can be beneficial for its in-pile performance. Besides,

关键词： Corrosion resistance

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Analysis of Age of Information in Non-terrestrial Networks

arXiv

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arXiv 2023年

作者： Lu, Yanwu Yang, Howard H. Pappas, Nikolaos Geraci, Giovanni Ma, Chuan Quek, Tony Q.S. ZJU-UIUC Institute Zhejiang University Haining China Department of Computer and Information Science Linköping University Linköping Sweden Telefonica Research Universitat Pompeu Fabra Barcelona Spain Zhejiang Lab Hangzhou China Information System and Technology Design Pillar Singapore University of Technology and Design Singapore

Non-terrestrial networks (NTN), particularly low Earth orbit (LEO) satellite networks, have emerged as a promising solution to overcome the limitations of traditional terrestrial networks in the context of next-generation (6G) wireless systems. In this paper, we focus on analyzing the timeliness of information delivery in NTN through the concept of Age of Information (AoI). We propose an on-off process to approximate the service process between LEO satellites and a source node located on the Earth’s surface. By utilizing stochastic geometry, we derive a closed-form expression for the time-average AoI in an NTN. This expression also applies to on-off processes with one component following an exponential distribution while the other has its probability density function supported on a bounded interval. Numerical results validate the accuracy of our analysis and demonstrate the impact of source status update rate and satellite constellation density on the time-average AoI. Our work fills a gap in the literature by providing a comprehensive analysis of AoI in NTN and offers new insights into the performance of LEO satellite networks. © 2023, CC BY.

关键词： Probability density function

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Analysis of Age of Information in Non-terrestrial Networks

Analysis of Age of Information in Non-terrestrial Networks

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IEEE Globecom Workshops

作者： Yanwu Lu Howard H. Yang Nikolaos Pappas Giovanni Geraci Chuan Ma Tony Q. S. Quek ZJU-UIUC Institute Zhejiang University Haining China Department of Computer and Information Science Linköping University Linköping Sweden Telefonica Research and Universitat Pompeu Fabra Barcelona Spain Zhejiang Lab Hangzhou China Information System and Technology Design Pillar Singapore University of Technology and Design Singapore

Non-terrestrial networks (NTN), particularly low Earth orbit (LEO) satellite networks, have emerged as a promising solution to overcome the limitations of traditional terrestrial networks in the context of next-generation (6G) wireless systems. In this paper, we focus on analyzing the timeliness of information delivery in NTN through the concept of Age of Information (AoI). We propose an on-off process to approximate the service process between LEO satellites and a source node located on the Earth's surface. By utilizing stochastic geometry, we derive a closed-form expression for the time-average AoI in an NTN. This expression also applies to on-off processes with one component following an exponential distribution while the other has its probability density function supported on a bounded interval. Numerical results validate the accuracy of our analysis and demonstrate the impact of source status update rate and satellite constellation density on the time-average AoI. Our work fills a gap in the literature by providing a comprehensive analysis of AoI in NTN and offers new insights into the performance of LEO satellite networks.

关键词：

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Modal Analysis of Lead-Bismuth Eutectic Flow in a Single Wire-Wrap Rod Channel

SSRN

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SSRN 2022年

作者： Zhao, Xielin Cheng, Qian Yu, Xiaofei Huang, Qian Zhang, Ke Feng, Zhipeng Zhou, Jinxiong State Key Laboratory for Strength and Vibration of Mechanical Structures School of Aerospace Xi'an Jiaotong University Xi'An710049 China Key Laboratory of Science and Technology on Reactor System Design Technology Nuclear Power Institute of China Chengdu610200 China

The thermal-hydraulics as well as flow-induced vibration of wire-wrapped rod bundles calls for accurate and efficient liquid metal flow simulation and prediction, yet it remains a challenge due to the complex geometries and high Reynolds number flow in wire-wrapped rod channel. Previous efforts towards this goal exclusively adopts full-order modeling (FOM), which is prohibitively computation-intensive. This work reports the first reference on modal analysis of the turbulent lead-bismuth eutectic (LBE) flow in a single wire-wrapped rod channel by a data-driven dynamic mode decomposition (DMD) method. The spatio-temporal data of fluid velocities and pressure were modelled and collected by using the Reynolds-averaged NavierStokes equations (RANS) approach with stress-omega RSM turbulence model. Model analysis was performed over the snapshot matrices and DMD modes and corresponding eigenvalues were calculated. The DMD modes and eigenvalues were then used to construct a reducedorder modeling (ROM) system for fast fluid field reconstruction and short-term forecasting. The correctness and feasibility of the method was demonstrated and compared with groundtruth CFD simulation results. Our method offers a fast and reliable approach for ROM of turbulent flow in wire-wrapped rod fuel assemblies. We publicize all the data and codes via https://***/XJTU-Zhou-group/Wire-wrapped-fuel-pin-CFD-DMD. © 2022, The Authors. All rights reserved.

关键词： Dynamic mode decomposition

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Verification of the 2D/1D coupling 3D transport code TIGER with C5G7 benchmarks

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International Journal of Advanced Nuclear reactor design and technology 2019年 1卷 43-50页

作者： Wu, Wenbin Yu, Yingrui Li, Qing Yao, Dong Luo, Qi Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

TIGER is a 2D/1D coupling 3D transport code developed by Nuclear Power Institute of China based on large-scale parallel computation. It employs 2D domain-decomposed parallel Matrix MOC in the radial direction and 1D finite difference diffusion in the axial direction. 2D domain-decomposed parallel Matrix MOC is accelerated with multi-group and multi-domain coupled PGMRES algorithm. Generally, 2D planar problem are solved independently and parallel degree is natural in the axial direction. Combination of the parallel degrees of both radial and axial directions is adopted in TIGER to achieve the large-scale parallel computation. In this paper, a few variations of C5G7 benchmarks were created based on the published benchmarks. Reference results of these variations were provided by the Monte Carlo code RMC. To demonstrate the accuracy and efficiency of TIGER, C5G7 benchmarks and these relevant variations were calculated by TIGER, and the comparisons were made with the published results and Monte Carlo results. © 2019 Xi'an Jiaotong University

关键词： Matrix algebra

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