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作者： Zhang, Zhizhu Wang, Kan Li, Qing Department of Engineering Physics Tsinghua University Beijing 100084 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu Sichuan Province 610041 China

ISBN: (纸本)9780791844953

The method of characteristics based on arbitrary trajectory adopts interpolation method to deal with the reflective boundary, which can break the restriction on the choice of trajectory layouts and quadrature sets. An acceleration and parallelization scheme is used to reduce the computational time. A generalized coarse-mesh finite difference (GCMFD) method which can be performed on generalized geometry is applied for acceleration. To effectively accelerate, we extend a single GCMFD method to the two-level GCMFD method, one level for the spatial acceleration and the other for the energy group acceleration. On the other hand, a parallelization method based on message-passing model uses an angular decomposition scheme. By grouping the directions to satisfy the reflective relation can effectively reduce the data communications. The numerical results show a good performance on reducing the number of iterations and speeding up the code after the acceleration and parallelization. Copyright ©2012 by ASME.

关键词： Acceleration

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Study on modeling of an integrated control and condition monitoring system for nuclear power plants

Study on modeling of an integrated control and condition mon...

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作者： CHEN Zhi YU Ren ZHANG Ying LIAO Long-tao Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China

The relationship between the control system of the nuclear power plant(NPP) and the condition monitoring system which provides support for the operator is very close, but in most nuclear power plant design, these two systems are designed separately, which affects the system compatibility, the utilization efficiency of the system resources, the extendibility of the systems and the real–time nature of the support, and may have some negative impacts on the plant operation. Focusing on this problem, an integrated design concept for the NPP control system and condition monitoring system is proposed in this paper. The overview scheme of the integrated system is given based on the analysis of the functions required. Furthermore, the study for modeling of the integrated control and condition monitoring system using the IDEF(Integration Definition Language) and UCM(Use Case Maps) methods is introduced in this paper.

关键词： modeling control and condition monitoring integrated system nuclear power plant

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Study on stress corrosion crack of austenitic stainless steel in simulated ocean environment

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Procedia Engineering 2012年 27卷 1538-1543页

作者： Meng Yan Qian Peng Qiwei Yin Science and Technology on reactor fuel and materials laboratory Nuclear Power Institute of ChinaP.O.Box436-4 610041ChengduChina Science and Technology on reactor system design technology laboratory Nuclear Power Institute of China P.O.Box622-502 610041ChengduChina

Recent studies on stress corrosion cracking properties of 321 bend pipe and pipe with weld, 316NG austenitic stainless steel pipe in ocean environment in virtue of slow strain rate tensile stress corrosion crack test are performed in different concentration of NaCl solution. Elongation and max tensile stress are selected as parameters to evaluate the SCC susceptibility based on the phenomenon that elongation and max stress fall as samples being exposed to NaCl solution environment, the results show that 316NG has the best stress corrosion crack resistance and 321 bend pipe materials behavior oppositely. In addition, the influence of differing strain rate and concentration of NaCl solution on properties of materials are researched, elongation increases along with tensile strain rate enhancement, mechanical properties are immune to variety of Cl- concentration from 3.5% to 26.5%.

关键词： stress corrosion crack austenitic stainless steel slow strain rate stress corrosion crack susceptibility

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Research on characteristic of the inverted annular flow regime during the narrow channel

Research on characteristic of the inverted annular flow regi...

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The Fifth China-Korea Workshop on Nuclear reactor Thermal Hydraulics

作者： Wei ZENG Science and Technology on Reactor System Design Technology

plate fuel assembly is widely used as the research reactor core geometry due to the narrow rectangular channel benefit, but the research on the post-CHF thermal-hydraulic characteristics in the narrow rectangular channel is few. Once the loss of coolant accident (LOCA) happens the post-CHF thermal-hydraulic characteristics is important for the accident mitigation. This paper studies the characteristics of the inverted annular flow regime during the narrow channel through the comparison between narrow and general channel inside tube heat reflooding experiment, give the assumptions of the post-CHF reflooding flow regime. Then through the comparison of narrow annular channel experimental wall temperature with the RELAP5 simulation wall temperature for this experiment process. The far downstream of the quench front heat flux is obviously lower than the calculated value, so the wall temperature is higher than the calculated wall temperature. The quality is assumed lower during the far downstream of the quench front in the narrow channel experiment. Because the liquid is consumed during the close downstream of the quench front. Through the comparison of the wall temperature between the calculated by code and experimental value, the liquid core in the inverted annular flow regime which may appears during close downstream of the quench front shortly will breakup earlier due to the more severe surrounding steam disturbing, bringing on the quickly consumption of the liquid, then the quality during far downstream of the quench front is higher than general channel.

关键词： RELAP Research on characteristic of the inverted annular flow regime during the narrow channel

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Development and Validation of a CFD Code for Direct Numerical Simulation

Development and Validation of a CFD Code for Direct Numerica...

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The Fifth China-Korea Workshop on Nuclear reactor Thermal Hydraulics

作者： Jie Li Science and Technology on Reactor System Design Technology

Direct numerical simulation is a powerful research tool, which provides a level of information and accuracy that cannot be equaled with other approaches. In this paper, the development of a CFD code for direct numerical simulation is described, which is named dnsPisoFoam. In order to validate the code, direct numerical simulation of channel flow with dnsPisoFoam was performed. The present results are compared with existing simulation results and shows good agreement.

关键词： Direct Numerical Simulation dnsPisoFoam Channel Flow

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Condition II Transients Analysis for Pellet Clad Interaction (PCI)

Condition II Transients Analysis for Pellet Clad Interaction...

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The Fifth China-Korea Workshop on Nuclear reactor Thermal Hydraulics

作者： Bi Shumao Shen Caifen Science and Technology on Reactor System Design Technology Laboratory

During an overpower transient, the fuel rod cladding may be subjected to major stresses due to differential expansion of the fuel and the cladding. This may lead to clad failure through the Pellet Clad Interaction (PCI) phenomenon. So the aim of this paper is to present the linear power reached during the most limiting condition II transients(Excessive Load Increase (ELI), Uncontrolled RCCA Withdrawal at Power (URWP) and undetected Rod Drop (RD)) with respect to Qinshan-II long cycle fuel management project PCI analysis.

关键词： ELI PCI Condition II Transients Analysis for Pellet Clad Interaction

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CFD Analysis on Hydrogen Distribution in Subcompartment of 600MW NPP under Severe Accident

CFD Analysis on Hydrogen Distribution in Subcompartment of 6...

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The Fifth China-Korea Workshop on Nuclear reactor Thermal Hydraulics

作者： ZOU Zhi-qiang ZHANG Yu DENG Jian Science and Technology on Reactor System Design Technology Laboratory

Hydrogen combustion in the containment building may be a threat to containment *** in some subcompartments,hydrogen detonation is more easier to happen,which may destroy the containment structure or the safety equipments in the containment. A study has been carried out using the GASFLOW three-dimensional CFD code to evaluate the hydrogen distribution in the subcompartment during a severe *** Chinese 600MW NPP containment is modeling by GASFLOW. The GASFLOW calculation gave detailed results for the spatial distribution of gas concentrations in the reactor coolant pump（RCP） compartment and the steam generator（SG） compartment within containment.

关键词： Subcompartment Hydrogen LBLOCA+ failure of ECCS CFD

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The precursory cooling characteristics of the reflooing in tight lattice

The precursory cooling characteristics of the reflooing in t...

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The Fifth China-Korea Workshop on Nuclear reactor Thermal Hydraulics

作者： Dan Wu Hongxing Yu Science and Technology on Reactor System Design Technology Laboratory

The advanced pressurized water reactor with a tight hexagonal lattice has its potential to improve uranium utilization. With a smaller pitch-to-diameter ratio(p/d) ranging from 1.06 to 1.20, a major problem is the emergency core cooling in a loss-of-coolant accident. The NEPTUN-III and FLORESTAN flooding experiments at PSI and KfK have been performed during the verification period 1985-1990, and the results shows that the reflooding behavior of LWHCR is quite different from that of LWR with higher peak clad temperatures and smaller quench rates. The existing system codes like RELAP5, CATHARE, TRAC may not be able to be used in the calculations of the reflooding phase of LWHCR. Though some efforts have been put into the validation of the improvement of codes, the results are not so good. In this study, the characteristics of the reflooding behavior of tight lattice are pointed out, and the deficiencies of the reflooding models of RELAP5/MOD3 are also fount out after a simulation of the NEPTUN-III reflooding test. The precursory cooling in tight lattice is not effective especially at low reflooding rates (<4cm/s), the droplet enhancement is not significant compared to LWR, and the vapor Reynolds number is much smaller. Finally, a few modifications to RELAP5/MOD3 are made. Compared with the original code, the modified one can better predict the reflooding phase of tight lattice especially the peak clad temperatures at low reflooding rates. More work should be done to deal with the heat transfer characteristics in the transition region of reflooding in tight lattice..

关键词： reflood tight lattice RELAP5 precursory cooling

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On energy-efficient trap coverage in wireless sensor networks

On energy-efficient trap coverage in wireless sensor network...

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2011 32nd IEEE Real-Time systems Symposium, RTSS 2011

作者： Li, Junkun Chen, Jiming He, Shibo He, Tian Gu, Yu Sun, Youxian State Key Lab. of Industrial Control Technology Zhejiang University China Computer Science and Engineering University of Minnesota United States Pillar of Information System Technology and Design Singapore University of Technology and Design Singapore Singapore

ISBN: (纸本)9780769545912

In wireless sensor networks (WSNs), trap coverage has recently been proposed to tradeoff between the availability of sensor nodes and sensing performance. It offers an efficient framework to tackle the challenge of limited resources in large scale sensor networks. Currently, existing works only studied the theoretical foundation of how to decide the deployment density of sensors to ensure the desired degree of trap coverage. However, the practical issues such as how to efficiently schedule sensor node to guarantee trap coverage under an arbitrary deployment is still left untouched. In this paper, we formally formulate the Minimum Weight Trap Cover Problem and prove it is an NP-hard problem. To solve the problem, we introduce a bounded approximation algorithm, called Trap Cover Optimization (TCO) to schedule the activation of sensors while satisfying specified trap coverage requirement. The performance of MinimumWeight Trap Coverage we find is proved to be at most O(ρ) times of the optimal solution, where ρ is the density of sensor nodes in the region. To evaluate our design, we perform extensive simulations to demonstrate the effectiveness of our proposed algorithm and show that our algorithm achieves at least 14% better energy efficiency than the state-of-the-art solution. © 2011 IEEE.

关键词： Sensor nodes

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Three-Dimensional Modeling of Heat Flow Field for Hot Dry Rock Crannies

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Procedia Engineering 2011年 15卷 4504-4510页

作者： Lun Li Dong-hong Si Ji-shun Li Yong-jian Yu Henan University of Science and Technology Henan Key Lab for Machinery Design and Transmission System Luoyang 471003 China

Owing to the shortage of traditional fossil energy, at present the use of geothermal energy has aroused people considerable attention. As a kind of clean and renewable geothermal resource, the hot dry rock will be widely applied. There is a large number of heat energy stored in hot dry rock. But the hot dry rock is usually located in deep-seated rocks of the earth. So it is rather difficult to utilize such deep resources directly. By means of working medium, heat energy could be delivered to ground and used properly. Usually, the heat exchange between medium and hot dry rock is achieved while the working medium flows through the rock crannies. The characteristic and structure of crannies in hot dry rock play a major role in heat transfer. It is very necessary to study characteristics of three-dimensional crannies and heat transfer effect of hot dry rack in order to reasonable development geothermal energy. The natural crannies in hot dry rock are quite narrow which cannot meet the needs of heat transport. The crannies used to heat exchange are usually produced by artificial explosion to obtain enough porosity. According to the distribution types of crannies after artificial explosion, The three-dimensional model of crannies is established, which is related to the identical porosity and variable porosities in different radius direction. In this paper, the hole with ideal shape is used to simulate crannies. The relationship among pressure, flux, velocity of working medium flowing through crannies and porosity are discussed based on fluid mechanics and heat transfer theory. The present study would have guiding significance in development and utilization of geothermal power.

关键词： geothermal power hot dry rock crannies porosity modeling heat exchange

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