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2020 International Conference on Physics of reactors: Transition to a Scalable Nuclear Future, PHYSOR 2020

作者： Zhao, Wenbo Yu, Yingrui Chai, Xiaoming Ning, Zhonghao Zhang, Bin Cai, Yun Liu, Kun Peng, Xingjie Yu, Junchong Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China

ISBN: (纸本)9781713827245

For accurate and efficient pin-by-pin core calculation of SP3 equations, a simplified two-node Coarse Mesh Finite Difference (CMFD) method with the nonlinear iterative strategy is proposed. In this study, the two-node method is only used for discretization of Laplace operator of the 0th moment in the first equation, while the fine mesh finite difference (FMFD) is used for the 2nd moment flux and the second equation. In the two-node problem, transverse flux is expanded to second-order Legendre polynomials. In addition, the associated transverse leakage is approximated with flat distribution. Then the current coupling coefficients are updated in nonlinear iterations. The generalized eigenvalue problem from CMFD is solved using Jacobi-Davidson method. A protype code CORCA-PIN is developed. FMFD scheme is implemented in CORCA-PIN as well. The 2D KAIST 3A benchmark problem and extended 3D problem, which are cell homogenized problems with strong absorber, are tested. Numerical results show that the solution of the simplified two-node method with 1×1 mesh per cell has comparable accuracy of FMFD with 4×4 meshes per cell, but cost less time. The method is suitable for whole core pin-wise calculation. © The Authors, published by EDP sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://***/licenses/by/4.0/).

关键词： Nonlinear equations

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Theoretical exploration of heat transfer characteristics of liquid metals

Theoretical exploration of heat transfer characteristics of ...

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2020 Transactions of the American Nuclear Society, ANS 2020

作者： Shen, Yaou Peng, Shinian Yan, Mingyu Zhang, Yu Deng, Jian Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China

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Research on thermal diffusion coefficient calculation for subchannels with spacer grid using CFD methodology 14

Research on thermal diffusion coefficient calculation for su...

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14th International Nuclear Fuel Cycle Conference, GLOBAL 2019 and Light Water reactor Fuel Performance Conference, TOP FUEL 2019

作者： Chen, Xi Du, Sijia Liu, Yu Qian, Libo Liu, Lili Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

Thermal Diffusion Coefficient (TDC) is one of the most important parameters in subchannel analysis codes. Abundant research results demonstrate that TDC is mainly determined by the structures of fuel assembly, especially by the mixing vanes of spacer grids. Traditionally, TDC is acquired by thermal-hydraulic tests. However, hydraulic tests cost a great deal of money and need long time, and it's impossible to test every grid design. Another new way to obtain coefficients economically and fast is really needed for decades. Recently, with great development of Computational Fluid Dynamics, CFD has been validated as an analysis method for nuclear engineering, especially for single phase calculation. This paper established CFD methodology in TDC calculation for a 5x5 rod bundle with spacer grids. Firstly, CFD simulations were carried out to get sunchannel exit temperature including different conditions, such as different temperature, pressure, and flow rate. Then subchannel code CORTH was used to make subchannel analysis with varied TDC. Finally, we compared the TDC using CFD method with that come from tests, and validation results show that the methodology was right. In conclusion, the feasibility of TDC calculation methodology is preliminarily validated, which provided references for developments and design of new fuel assemblies. Copyright © GLOBAL 2019 - International Nuclear Fuel Cycle Conference and TOP FUEL 2019 - Light Water reactor Fuel Performance *** rights reserved.

关键词： Computational fluid dynamics

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Capillary Evaporating Film Model for a Screen-Wick Heat Pipe

SSRN

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SSRN 2022年

作者： Ma, Yugao Zhang, Yingnan Yu, Hongxing Huang, Shanfang Deng, Jian Chai, Xiaoming Zeng, Chang Zhang, Zhuohua He, Xiaoqiang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Department of Engineering Physics Tsinghua University Beijing100084 China

Screen-wick heat pipes are efficient passive heat transfer devices. The heat transfer capacity is determined by the capillary pressure, which is related to the film curvature inside the screen wick. A capillary evaporating film model was developed for the screen wick that divided the film into a capillary pressure microlayer region and a macroscopic film. The film surface shape in the capillary pressure microlayer region is mainly influenced by the long-range molecular forces (disjoining pressure) and the surface tension, while the film surface shape in the macroscopic film is affected by the wick geometry. The numerical results show that the present model more accurately predicts the three-dimensional characteristics of the liquid film inside the screen wick than the classical model. The wire opening distance and the wire diameter affect the capillary pressure and the flow path in the wick. As the liquid film recedes into the wick, the capillary force first increases and then decreases. The film dynamics in the wick are related to the liquid height, which automatically adapts to the required evaporation and pressure balance for a given heat load. High operating temperatures can lead to a mismatch between the capillary head and the pressure loss, leading to dry out in the wick. Thus, this work provides a reference for operating alkali-metal wick heat pipes. © 2022, The Authors. All rights reserved.

关键词： Heat pipes

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Perceived vs. Objective Human Performance in Diagnostic Tasks: Under-Confidence or Over-Confidence?

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SSRN 2022年

作者： Lyu, Xi Li, Zhizhong Ma, Quan She, Manrong Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Department of Industrial Engineering Tsinghua University Beijing100084 China

Humans are not very good at assessing their own performance, and usually exhibit over-confidence. Little effort has been done to investigate how and how well diagnosticians perceive their performance of sub-processes of diagnosis, for example information seeking and information integration. This study analyzed the performance data of an experiment of diagnosing an accident in a simulated nuclear power plant. The objective performance was measured by eight indicators and the perceived performance was measured by three indicators. Difference relations and correlations between these indictors were explored. Results showed that on one hand there were systematic deviations between perceived and objective performance, on the other hand the perceptions did have some validity. Perceptions of information seeking manifested under-confidence while perceptions of information integration and the overall diagnosis manifested over-confidence. The authors argue that these two biases were mutually complementary and facilitating rather than contradictory. The findings could be used to help diagnosis-related training, operation and decision making. © 2022, The Authors. All rights reserved.

关键词： Information retrieval

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Study on flow modes of open natural circulation with low height difference under low power conditions

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International Journal of Advanced Nuclear reactor design and technology 2020年 2卷 10-14页

作者： Yi, Li Jianchuang, Sun Hang, Peng Cheng, Xiang Quan, Biao Cao, Xiaxin Jian, Zhou Ming, Ding Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Harbin Engineering University Harbin150001 China

Open natural circulation systems are widely applied in the field of energy and chemical industries. Under some special conditions, open natural circulation systems with low height difference need to be applied, but research on this type of systems is not sufficient. In this paper, the flow modes of sucha natural circulation system were experimentally studied at low power level by adopting steam heating. In addition, the flow modes and physical phenomena of the natural circulation system were analyzed in detail under different heating power conditions. It is found that there are four flow modes at different power levels in the natural circulation system due to the influence of non-condensable gas and subcooled boiling. The inlet and outlet temperatures of heating section are analyzed in different flow modes. The result shows that the outlet temperature of heating section can be used as a judgment criterion for different flow modes. © 2019

关键词： Chemical industry

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Applying multi-scale simulations to materials research of nuclear fuels:A review

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Materials Reports(Energy) 2021年第3期1卷 64-80页

作者： Chunyang Wen Di Yun Xinfu He Yong Xin Wenjie Li Zhipeng Sun School of Nuclear Science and Technology Xi'an Jiaotong UniversityXi'an710049China State Key Laboratory of Multiphase Flow Xi'an Jiaotong UniversityXi'an710049China China Institute of Atomic Energy Beijing102413China Key Laboratory of Nuclear Reactor System Design Technology Nuclear Power Institute of ChinaChengdu610213China

Computational simulation is an important technical means in research of nuclear fuel *** nuclear fuel issues are inherently multi-scopic,it is imperative to study them with multi-scale simulation *** present,the development of multi-scale simulation for nuclear fuel materials calls for a more systematic approach,in which lies the main purpose of this *** most important thing in multi-scale simulation is to accurately formulate the goals to be achieved and the types of methods to be *** this regard,we first summarize the basic principles and applicability of the simulation methods which are commonly used in nuclear fuel research and are based on different scales ranging from micro to macro,***-Principles(FP),Molecular Dynamics(MD),Kinetic Monte Carlo(KMC),Phase Field(PF),Rate Theory(RT),and Finite Element Method(FEM).And then we discuss the major material issues in this field,also ranging from micro-scale to macro-scale and covering both pellets and claddings,with emphasis on what simulation method would be most suitable for solving each of the ***,we give our prospective analysis and understanding about the feasible ways of multi-scale integration and relevant handicaps and challenges.

关键词： Computational simulation Nuclear fuel Multi-scale modeling Irradiation behavior

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Safety assessment of UN/Zr fuel with SiC cladding under large break loss-of-coolant accident 14

Safety assessment of UN/Zr fuel with SiC cladding under larg...

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14th International Nuclear Fuel Cycle Conference, GLOBAL 2019 and Light Water reactor Fuel Performance Conference, TOP FUEL 2019

作者： Qian, Libo Yu, Hongxing Sun, Yufa Deng, Jian Wu, Dan Ding, Shuhua Chen, Wei Li, Zhongchun Chen, Xi Liu, Lili Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu Sichuan610213 China

Accident Tolerant Fuel (ATF), which is aiming at upgrading safety characteristics of nuclear fuel and cladding under design basis and design extension conditions, has drawn more and more attention since Fukushima accident. By virtue of improved basic properties and oxidation resistance comparing with conventional UO2-Zr, UN(Particle)/Zr(Matrix) fuel pin and SiC cladding (UN/Zr-SiC) is expected to slow down accident progression and to provide wider margin of coping time. In present paper, the improved performance of UN/Zr-SiC fuel system on the Large Break Loss-Of-Coolant-Accident (LB LOCA) is analyzed by Appendix K version of ARSAC code (ARSAC-K). For this reason, the corresponding models in ARSAC-K are modified to achieve the goal: 1) thermal physical properties of SiC;2) equivalent thermal physical properties of UN/Zr composite fuel;3) passive oxidation model of SiC under pure steam condition based on modified Deal-Grove model together with linear volatilization model of SiO2 based on heat/mass transfer analogy. Obtained quantitative results show promising safety enhancement in terms of peak cladding temperature (PCT): the PCT of UN/Zr-SiC fuel is much lower than that of UO2-Zr fuel. Then due to the great safety margin of UN/Zr-SiC fuel under LB LOCA condition, an exploratory investigation of the reduction of safety injection capacity and the increase of reactor nominal power under LB LOCA condition is presented. The results show that from the LB LOCA point of view, UN/Zr-SiC fuel has the potential can to be utilized to reduce safety injection capacity or increase reactor nominal power without reducing the safety margin. Therefore, UN/Zr-SiC fuel is demonstrated to have positive effects on safety and capability of reactor design optimization. Copyright © GLOBAL 2019 - International Nuclear Fuel Cycle Conference and TOP FUEL 2019 - Light Water reactor Fuel Performance *** rights reserved.

关键词： Silicon carbide

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Simulation analysis on the pressurizer degassing sub-system of module small reactor (ACP100)

Simulation analysis on the pressurizer degassing sub-system ...

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

作者： Zhiyun, Cai Yun, Ren Jianyong, Lai Yulong, Zhang Hang, Liu Xianghong, Liu Minghao, Liu Zhu, Ye Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Sichuan Chengdu610041 China

ISBN: (纸本)9780791883778

A pressurizer degassing sub-system is designed in Module Small reactor(ACP100), which can be used to vent the noncondensable gas dissolved in reactor Coolant during plant shutdown period by opening the remote degassing valve installed on top of the pressurizer. In order to verify the transient characteristic during the whole degassing process, a dedicated transient degassing program is developed based on the improved non-equilibrium multi-region model and the transient degassing model, which is used then to carry out a simulation analysis on this process. Also, the boundary condition models including pressurizer heater power model, pressure spray model, surge line flow model and critical flow model for degassing valve are established. The simulation results show that, under ultimate condition of hot-zero power operation, during the whole degassing process, the Pressurizer's pressure drops to a maximum 0.038MPa, and the water level is raised 0.0637m above the normal level, which means, both of the pressure and water level are within the normal operation band and shall not initiate any safety signal. Meanwhile, the whole transient process lasts about 16 minutes, and then it enters into the stable degassing period. The gas concentration vs time curve is very smooth. It takes about 5.8 hours to remove the gas dissolved in reactor Coolant from 35 ml(STP)/kg to 15 ml(STP)/kg. The analysis shows the Pressurizer Degassing Sub-system is safety, effectively and reliable. Copyright © 2020 ASME

关键词： Plant shutdowns

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Optimization design for the configuration parameters of helical-coil steam generator volume

Optimization design for the configuration parameters of heli...

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

作者： Fang, Hongyu Wang, Li Zhu, Dahuan Cai, Rong Jiang, Xiaowei Zhang, Dan Qian, Libo Wu, Dan Science and Technology on Reactor System Design Technology Laboratory Chengdu China Sun YAT-SEN University Guangzhou China

ISBN: (纸本)9780791883785

With the development of the nuclear energy industry, small modular reactors (SMRs) have become an important option in China's energy development due to their advantages in terms of safety and economics. The helical-coil steam generator is an important part of SMR, and the structure parameters need to be optimized urgently to reduce costs and improve safety. In this paper, various thermohydraulic parameters were used as indicators for the design quality of the helical-coil steam generator, such as the volume of the equipment, velocity of the flow, maximum temperature of the tubes, and natural circulation capability. The optimization of these target parameters has important theoretical and practical values. The genetic algorithm method is widely used to processes data efficiently, and it is able to reach a optimum design rapidly, which makes it a good choice for the optimization of parameters. The results show that this method could efficiently reduce the volume of the helical coil steam generator. © 2020 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Genetic algorithms

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