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Adding a third level of parallelism to OpenMOC, an open source deterministic neutron transport solver

Adding a third level of parallelism to OpenMOC, an open sour...

2019 International Conference on Mathematics and Computational Methods Applied to Nuclear science and Engineering, M and C 2019

作者： Giudicelli, Guillaume Wu, Wenbin Josey, Colin Smith, Kord Forget, Benoit Nuclear Science and Engineering Department Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge02139 United States Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China Los Alamos National Laboratory New Mexico United States

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Phase distribution characteristics of cap bubbly flow in 5×5 rod bundles with mixing vane spacer grids 27

Phase distribution characteristics of cap bubbly flow in 5×...

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27th International Conference on Nuclear Engineering: Nuclear Power Saves the World!, ICONE 2019

作者： Ren, Quan-Yao Pu, Zeng-Ping Pan, Liang-Ming Zheng, Mei-Yin Wang, Hao-Yu Zhou, Wen-Xiong Wei, Lie 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 Chongqing400044 China

ISBN: (纸本)9784888983051

To improve the understanding on the mechanisms of phase distribution and bubble interaction for cap bubbly flow in rod bundles, the adiabatic upward cap bubbly flow has been investigated experimentally in 5×5 rod bundles with prototypical mixing vane spacer grids (MVSGs). Miniaturized four-sensor conductivity probe (MFSCP) has been developed to measure the local two phase flow parameters, such as void fraction, interfacial area concentration (IAC), bubble velocity, and bubble chord length. The detailed local parameters in cap bubbly flow has been measured and analyzed, based on which the phase distribution characteristics have been analyzed for Group I and II bubbles in detail. Moreover, the axial development and the effect of MVSG have also been analyzed. Some interesting phenomenon have been observed: Group I void fraction profile is almost flat at the measuring line while Group II void fraction profile has the skewed peaks near the sub-channel center resulted for the limitation of rod walls and the strong secondary flow;Group I IAC is the main contribution to the total IAC, whose profile has the peaks near the rod gap due to the smaller bubble size near the rod walls. For current cap bubbly flow condition, the bubble velocity and size are the two determined factors for Group I IAC for the similar void fraction, while the void fraction is the key factor for Group II IAC for the larger bubble size. Furthermore, because of the shear force of MVSG and induced stronger turbulence, the large Group II bubbles break up into Group I bubbles and smaller Group II bubbles, which results in the smaller bubble size and larger Group I void fraction and IAC. According to the analysis on the axial development of local parameter profiles, the MVSG dissipation length might be larger than 19.4 L/Dh, but smaller than 32.1 L/Dh for current cap bubbly flow condition. Copyright © 2018-2019 by JSME

关键词： Void fraction

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A New Tone Mapping Operator Based on Two-layer Model 2

A New Tone Mapping Operator Based on Two-layer Model

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2nd IEEE International Conference on Information systems and Computer Aided Education, ICISCAE 2019

作者： Wu, Pei Hu, Congliang Luo, Nanhang Tao, Li Zheng, Wei Second Institute for Wuhan Ship Development and Design Wuhan China National Key LAB of Science and Technology Steam Power System for NS China

ISBN: (纸本)9781728130668

Tone mapping is a process of compressing high dynamic range image data into low dynamic range data according to specific rules, so that the image can be displayed on ordinary display devices. The specific rules are called tone mapping operators. Nowadays, the mainstream tone mapping operator can be divided into two kinds, the global operators and the local operators. This paper processes a new tone mapping operator based on two-layer model. Our operator combines the characteristics of global operators and local operators, and it can effectively compress the high dynamic range images with an excellent performance. © 2019 IEEE.

关键词： Display devices

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Improvements of the CMFD acceleration capability of OpenMOC

Improvements of the CMFD acceleration capability of OpenMOC

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2019 International Conference on Mathematics and Computational Methods Applied to Nuclear science and Engineering, M and C 2019

作者： Wu, Wenbin Giudicelli, Guillaume Smith, Kord Forget, Benoit Yao, Dong Luo, Qi Department of Nuclear Science and Engineering Massachusetts Institute of Technology 77 Massachusetts Ave CambridgeMA02139 United States Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China NO. 328 Section 1 Changshun Ave Shuangliu District Chengdu Sichuan Province610213 China

ISBN: (纸本)9780894487699

Due to its computational efficiency and geometrical flexibility, the Method of Characteristics (MOC) has been widely used for light water reactor lattice physics analysis. Usually acceleration methods are necessary for MOC to achieve acceptable convergence on practical reactor physics problems. Among them, Coarse Mesh Finite Difference (CMFD) is very popular and can drastically reduce the number of transport iterations. In OpenMOC, CMFD acceleration was implemented but had the limitation of supporting only a uniform CMFD mesh, which would often lead to splitting MOC source regions, thus creating an unnecessary increase in computation and memory use. In this study, CMFD acceleration with a nonuniform Cartesian mesh is implemented into OpenMOC. We also propose a quadratic fit based CMFD prolongation method in the axial direction to further improve the acceleration when multiple MOC source regions are contained in one CMFD coarse cell. Numerical results are presented to demonstrate the improvement of the CMFD acceleration capability in OpenMOC in terms of both efficiency and stability. © 2019 American Nuclear Society. All rights reserved.

关键词： Acceleration

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Surrogate representation of sink strengths and the long-term role of crystalline interfaces in the development of irradiation-induced bubbles

arXiv

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arXiv 2020年

作者： Luo, Jing Xin, Yong Zhou, Zhengcheng Zhu, Yichao Guo, Xu Department of Engineering Mechanics Dalian University of Technology Dalian116023 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology China International Research Center for Computational Mechanics Dalian University of Technology China

The present article addresses an early-stage attempt on replacing the analyticity-based sink strength terms in rate equations by surrogate models of machine learning representation. Here we emphasise, in the context of multiscale modelling, a combinative use of machine learning with scale analysis, through which a set of fine-resolution problems of partial differential equations describing the (quasi-steady) short-range individual sink behaviour can be asymptotically sorted out from the mean-field kinetics. Hence the training of machine learning is restrictively oriented, that is, to express the local and already identified, but analytically unavailable nonlinear functional relationships between the sink strengths and other local continuum field quantities. With the trained models, one is enabled to quantitatively investigate the biased effect shown by a void/bubble being a point defect sink, and the results are compared with existing ones over well-studied scenarios. Moreover, the faster diffusive mechanisms on crystalline interfaces are distinguishingly modelled by locally planar rate equations, and their linkages with rate equations for bulk diffusion are formulated through derivative jumps of point defect concentrations across the interfaces. Thus the distinctive role of crystalline interfaces as partial sinks and quick diffusive channels can be investigated. Methodologicalwise, the present treatment is also applicable for studying more complicated situation of long-term sink behaviour observed in irradiated materials. Copyright © 2020, The Authors. All rights reserved.

关键词： Machine learning

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Study on surface pore characteristic and hydrophilicity of carbon materials in HTGR 27

Study on surface pore characteristic and hydrophilicity of c...

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27th International Conference on Nuclear Engineering: Nuclear Power Saves the World!, ICONE 2019

作者： Ma, Sheng-Chao Shen, Kai-Yue Yin, Hua-Qiang He, Xue-Dong Li, Jun Meng, Ying-Chao Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy Technology Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education Tsinghua University Beijing100084 China Nuclear Power Design and Research Sub-institute Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Institute for Chemical and Bioengineering Department of Chemistry and Applied Biosciences Swiss Federal Institute of Technology Zurich Zurich8093 Switzerland

ISBN: (纸本)9784888983051

Lots of porous carbon materials, including boron-containing carbon (BC) and isostatic pressure graphite (IG-110), are used in high-temperature gas cooled reactor (HTGR). To prevent corrosion caused by carbon-water reaction at high temperature, water absorbed in the materials needs to be removed before the reactor operation. It has become the consensus of the researchers that the pore morphology of the material has an important influence on the physical adsorption and desorption process of the gas. Therefore, it is significant to explore the migration mechanism of moisture in carbon materials by studying the pore characteristics and hydrophilic properties of the material surface. Scanning electron microscopy (SEM) and contact angles tests were used to study the surface pore characteristic and hydrophilicity of BC and IG-110. The results of SEM scanning show that a large number of irregular micropores and cracks were found on the surface of BC, while the structure of IG-110 was more compact, and the size and number of pores were obviously smaller. 3 μL and 5 μL water drops were used to contact angle tests, it was found that the average contact angle of the BC surface with water droplets is 118.04°, which is greater than that of IG-110, measured as 112°. Finally, the water vapor absorption experiment of these two materials were carried out to verify that the pore structure and hydrophilicity have an effect on water absorption, and the pore structure has a more decisive effect on moisture absorption than the hydrophilicity. © 2019 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Scanning electron microscopy

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Neutron physical feasibility of small modular design of dual fluid reactor 27

Neutron physical feasibility of small modular design of dual...

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27th International Conference on Nuclear Engineering: Nuclear Power Saves the World!, ICONE 2019

作者： Wang, Xiang Zhang, Qian He, Xun Du, Zhuoqi Seidl, Marcus Macian-Juan, Rafael Czerski, Konrad Dabrowski, Mariusz College of Nuclear Science and Technology Harbin Engineering University Harbin Heilongjiang China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu Sichuan China Institute of Nuclear Engineering Technical University of Munich Garching Bayern Germany Faculty of Mathematics and Physics University of Szczecin Szczecin Poland

ISBN: (纸本)9784888983051

The Dual Fluid reactor (DFR) is a fast reactor concept proposed by the Institute of Solid-state- and Nuclear physics (IFK) in Berlin. The design of DFR aims to combine the Gen-IV Molten Salt reactor (MSR) and the Liquid-Metal Cooled reactor (SFR, LFR), which means that the molten-salt fuel is no more used as coolant while the heat is removed in a separate loop by liquid lead, to improve these two concepts. Without control rods, DFR is given hope to react and take steps to the change of operation conditions automatically by its inertial negative temperature feedback. Since fuel and coolant are both liquid, the circulation speed of each liquid is considered capable to adjust operational parameters for DFR. The original design of a 3000MWth (Wang, 2017) and a downscaled version of 500MWth (He, 2016) were analyzed in the aspects of reactor physics and thermal-hydraulics. For the practical purpose, this paper has proposed a small modular version of the DFR, which has power output of 2MWth. The reactor with such power level is expected in various applications. Therefore, it is necessary to perform the more explicit analysis on the design than the previous ones. The analysis focuses on the neutronic calculations with the default fuel salt of U-Pu mixture under steady state conditions. Copyright © 2018-2019 by JSME

关键词： Coolants

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The application of Deep Reinforcement Learning in Coordinated Control of Nuclear reactors

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Journal of Physics: Conference Series 2021年第1期2113卷

作者： Jing Li Yanyang Liu Xianguo Qing Kai Xiao Ying Zhang Pengcheng Yang Yue (Marco) Yang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu 610213 China Department of Engineering The University of Sydney Sydney 2006 Australia

The nuclear reactor control system plays a crucial role in the operation of nuclear power plants. The coordinated control of power control and steam generator level control has become one of the most important control problems in these systems. In this paper, we propose a mathematical model of the coordinated control system, and then transform it into a reinforcement learning model and develop a deep reinforcement learning control algorithm so-called DDPG algorithm to solve the problem. Through simulation experiments, our proposed algorithm has shown an extremely remarkable control performance.

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A Reduced-order Extrapolation Model Based on Proper Orthogonal Decomposition Technique for Rayleigh–Bénard convection

A Reduced-order Extrapolation Model Based on Proper Orthogon...

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第二届材料科学应用与能源材料国际研讨会

作者： Jinghua Yang Dengfeng Lu Zhiguang Deng Xiang Guan Qing Shi Sichuan Electric Power Design & Consulting Co. Ltd National Key Labortory of Science and Technology on Reactor System Design Technology

In order to quickly calculate the flow characteristics in the simulated two-dimensional Rayleigh–Bénard convection model,a reduced-order extrapolation difference model for solving two-dimensional Rayleigh–Bénard is established based on the Proper Orthogonal Decomposition(POD) ***,the classical difference format is used to calculate the flow field on the initial time span,the sample data is to construct the POD basis,and the truncation error generated in the process of constructing the POD base is ***,the two-dimensional reduced-order extrapolation Rayleigh–Bénard model is constructed by combining the SVD and POD *** numerical examples,the classical difference model and the reduced-order extrapolation model are numerically simulated under the given initial boundary *** reliability and effective of the reduced-order method are verified by comparing the flow field temperature cloud maps in the two calculation stages.

关键词： POD A Reduced-order Extrapolation Model Based on Proper Orthogonal Decomposition Technique for Rayleigh nard convection Model

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A method for predicting the configuration of corium pool in RPV lower plenum

A method for predicting the configuration of corium pool in ...

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2018 International Congress on Advances in Nuclear Power Plants, ICAPP 2018

作者： Liu, Lili Yu, Hongxing Chen, Liang Jian, Deng Chunrui, Deng Dan, Zhang Xiaoli, Wu Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

ISBN: (纸本)9780894487552

The configuration of a corium pool in the lower plenum of reactor vessel is very important for validity of maintaining reactor vessel integrity under IVRERVC (In-Vessel corium Retention through External reactor Vessel Cooling) condition. A method is designed to predict the configuration of corium pool for an Advanced China PWR, call ACP1000 after entire melt dropping into the lower plenum. It takes into account both thermo-chemical reaction of oxides and metals in corium and the influence of different paths of corium relocated from core region into the lower plenum. The reasons why a three-layer pool has not been observed in the MASCA and COSMOS tests are given by this method. The method is applied to investigate the corium configuration of ACP1000 after a hypothetical station blackout (SBO) accident. It is shown that the stratification of the corium pool is related to the relocation paths of the corium. In the case of downward relocation, a two-layer melt pool with a metal layer on the top is formed. For the sideward relocation, the configuration shows a stratified pool consisting of a dense metal layer on the bottom, an oxide layer in the middle and a light metal layer on the top. © 2018 American Nuclear Society. All rights reserved.

关键词： Pressurized water reactors

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