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Analysis of accidental loss of pool coolant due to leakage in a PWR SFP

Annals of Nuclear Energy 2015年 77卷 65-73页

作者： Xiaoli Wu Wei Li Yapei Zhang Wenxi Tian Guanghui Su Suizheng Qiu State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi’an Jiaotong University No. 28 Xianning West Road Xi’an Shanxi 710049 China

A large loss of pool coolant/water accident may be caused by extreme accidents such as the pool wall or bottom floor punctures due to a large aircraft strike. The safety of SFP under this circumstance is very important. Large amounts of radioactive materials would be easily released into the environment if a severe accident happened in the SFP, because the spent fuel pool (SFP) in a PWR nuclear power station (NPS) is often located in the fuel handing building outside the reactor containment. To gain insight into the loss of pool coolant accident progression for a pressurized water reactor (PWR) SFP, a computational model was established by using the Modular Accident Analysis Program (MAAP5). Important factors such as Zr oxidation by air, air natural circulation and thermal radiation were considered for partial and complete drainage accidents without mitigation measures. The calculation indicated that even if the residual water level was in the active fuel region, there was a chance to effectively remove the decay heat through axial heat conduction (if the pool cooling system failed) or steam cooling (if the pool cooling system was working). For sensitivity study, the effects of emergency ventilation and water injection on the accident progression were analyzed. The analysis showed that for the current configuration of high-density storage racks, it was difficult to cool the spent fuels by air natural circulation. Enlarging the space between the adjacent assemblies was a way of increasing air natural circulation flow rate and maintaining the coolability of SFP. Water injection to the bottom of the SFP helped to recover water inventory, quenching the high temperature assemblies to prevent melting, and even the molten corium pool to avoid molten-corium-concrete-interaction (MCCI).

关键词： Spent fuel pool MAAP5 Loss of pool coolant Mitigation measures

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A study of the effect of microstructure on liquid-solid impact

A study of the effect of microstructure on liquid-solid impa...

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International Conference on power engineering, ICOPE 2015

作者： Teng, Zhaohui Li, Na Zhou, Qulan Chen, Xi State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Department of Earth and Environmental Engineering Columbia University New YorkNY10027 United States International Center for Applied Mechanics SV Lab School of Aerospace Xi'an Jiaotong University Xi'an710049 China

Liquid drops hit against solid surface, which has an enormous influence on the mechanical properties of base solid surface during its service. Impact of the droplet makes the solid surface and some internal section of the base solid material generate high stress. The conical microstructure may decrease the dimensionless equivalent stress in solid. We investigated the effect of the microstructure with three different sizes by numerical simulation. In the paper, detail theoretic analyses of liquid-solid impact were carried out. Here the mathematics physics model was built to solve the liquid-solid impact problem The numerical method coupling liquid and solid region was designed and the impact procedure of spherical droplet to solid materials was simulated. We acquired the pressure distribution inside water drop and the transient equivalent stress field inside solid. High stress at the solid surface and some internal sections arose from impact of the droplet. The sections in solid with highest stress can be classified into the contact edge and the axis due to stress superposition. The stress in solid declined slightly at the condition with the microstructure (5μm high and a diameter of 1μm). The microstructure (50μm high and a diameter of 10μm) in this paper considerably decreased the average stress in solid. They may store liquid and yield a liquid film higher than the thickness of the microstructure, undertaking the droplet impact and acting as a cushion to the stress concentration in solid. These results may play a role in evaluating the base solid service properties based on the fundamental solution of liquid-solid impact and be valuable to understand the internal mechanism of liquid-solid impact, and are helpful to prevent the erosion of droplet to the solid materials. © 2015 The Japan Society of Mechanical Engineers.

关键词： Microstructure

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Erosion of Premium Connection Cross-over Joint in Solid-liquid flow

Erosion of Premium Connection Cross-over Joint in Solid-liqu...

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The 2015 2nd International Conference on engineering Technology and Application

作者： Yong'an Zhao Wenbin Cai Lu Cui Jiarui Cheng Yihua Dou School of Mechanical Engineering Xi'an Shiyou University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University School of Mechanical Engineering Xi'an Shiyou University

Hydraulic fracturing is a new technique which is used in oil yield to maximize its own *** pumping of fracturing slurry flow through tubing collar can cause considerable mass loss of inner surface *** may pose a significantly potential risk even a well ***,the erosion phenomenon is particularly serious in the structure of variable *** simulation in this paper was used to get particle impact parameters,and it is combined with jet experiments to find out the main factors of BG-13 Cr mass ***,the equation with experimental data was applied to predict erosion rate of premium connection cross-over joint inner wall.

关键词： premium connection erosion rate numerical simulation Jet flow experiments

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Numerical Simulation on the Laser Induced Oxygen Spark under Different Ambient Conditions

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Energy Procedia 2015年 75卷 2409-2414页

作者： Liu Jiping Chen Keqiang Zhang Xiaobo Wang Jinshi Yan Junjie Yoshiro Deguchi Moe Key Laboratory of Thermo-Fluid Science and Engineering Xi’an Jiaotong University Xi’an 710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China Department of Mechanical Engineering The University of Tokushima Tokushima 770-8501 Japan

As a new type of ignition technique, laser induced spark ignition can be widely used in the ignition system of internal combustion engines and aero-engines. In this paper, laser induced oxygen spark evolution has been numerically studied with a two-dimensional, unsteady, multi-components and time-accurate model under different ambient temperatures and pressures. The chemical kinetics between species has been considered. A commercial software Fluent is used to solve the problem. Results show that both ambient conditions have great effect on the maximum temperature and maximum pressure of oxygen spark initially, but the effect decreases with time going on. The maximum velocity and maximum electron number density are also prominently influenced by ambient conditions. For the relationship between shock wave radius and time, ambient temperature plays an important role while ambient pressure is insignificant. These results above will be the foundation for the applications of laser induced spark ignition in the future.

关键词： laser induced ignition Oxygen Spark Ambient Factors Numerical Simulation

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Progress in hydrogen enriched hydrocarbons combustion and engine applications

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Frontiers in Energy 2014年第1期8卷 73-80页

作者： Zuohua HUANG Jinhua WANG Erjiang HU Chenglong TANG Yingjia ZHANG State Key Laboratory of Multiphase Flow in Power Engineering Xi'anJiaotong University Xi'an 710049 China

The paper summarized the work on hydrogen enriched hydrocarbons combustion and its application in engines. The progress and understanding on laminar burning velocity, flame instability, flame structure flame and chemical kinetics were presented. Based on funda- mental combustion, both homogeneous spark-ignition engine and direct-injection spark-ignition engine fueled with natural gas-hydrogen blends were conducted and the technical route of natural gas-hydrogen combined with exhaust gas recirculation was proposed which experimen- tally demonstrated benefits on both thermal efficiency improvement and emissions reduction.

关键词： hydrogen enriched hydrocarbon combustion,fundamental study engine application

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Novel flow behaviors induced by a solid particle in nanochannels: Poiseuille and Couette

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Chinese Science Bulletin 2014年第20期59卷 2478-2485页

作者： Cheng-Zhen Sun Wen-Qiang Lu Bo-Feng Bai Jie Liu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University College of Physical Sciences University of Chinese Academy of Sciences

We conducted a molecular dynamics(MD)simulation to address the novel flow behaviors induced by a solid particle in *** basic flows,i.e.,Poiseuille and Couette,are involved in this *** Poiseuille flow,the distribution of number density exhibits fluctuations in the center of channel and near the walls,which are caused by the strong interactions from the atoms of particle and *** stronger external driving forces,the fluid atoms move toward the center of channel and some cavities appear in the fluidic *** external driving forces and bigger particles make the fluid moving quickly in *** Couette flow,the particle rotates under the velocity difference among particle atoms in the shear *** fluid atoms near the walls become infrequent and move to the center of *** velocities of the centrally-located fluid atoms decrease owing to the particle,resulting in an untypical non-linear Couette *** summary,the solid particle brings new fluid–solid interface and interactions,which induce several novel behaviors in nanochannel flows.

关键词：流动行为纳米通道固体粒子 Poiseuille流诱发 Couette流强相互作用固体颗粒

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Simulation of the PHEBUS FPT-1 experiment using MELCOR and exploration of the primary core degradation mechanism

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Annals of Nuclear Energy 2015年 85卷 193-204页

作者： Jun Wang Michael L. Corradini Wen Fu Troy Haskin Yapei Zhang Wenxi Tian Guanghui Su Suizheng Qiu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China College of Engineering The University of Wisconsin-Madison Madison 53706 United States Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China

Core degradation evaluation of probability, progression and consequences of a core degradation accident is critical for evaluation of risk as well as its mitigation. However, research and modeling of severe accidents to date are limited, and their accuracy in predicting severe accident consequences is still insufficient. It is therefore important to explore the mechanisms of core degradation and to develop mitigation measures for severe accidents. PHEBUS FPT1 is a typical and classic core degradation experiment. MELCOR is a world famous severe accident analysis code developed by Sandia National Lab that has seen wide application, a broad user base, and a number of supporting experiments. The PHEBUS experiment was simulated using MELCOR in this paper. Experimental data on, thermal power and steam mass flow rates are used to determine average pressure, energy distribution, molten mass, temperature of the fuel, and hydrogen generation. Data from the PHEBUS experiment and Cho’s calculations are used to compare the average pressure, several fuel temperatures and the hydrogen generation rate. The results confirm the validity of MELCOR’s simulation of the PHEBUS experiment. The temperature distribution of the core is provided. These results are used to determine the mode and behavior of core degradation with the intent of building a foundation for further research.

关键词： PHEBUS FPT1 MELCOR Core degradation

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Improvement on Quantitative Measurement of Fly Ash Contents Using Laser-Induced Breakdown Spectroscopy

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Journal of flow Control, Measurement & Visualization 2015年第1期3卷 10-21页

作者： Zhenzhen Wang Yoshihiro Deguchi Hiroaki Watanabe Ryoichi Kurose Junjie Yan Jiping Liu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China Graduate School of Advanced Technology and Science The University of Tokushima Tokushima Japan Energy Engineering Research Laboratory The Central Research Institute of Electric Power Industry Kanagawa Japan Department of Mechanical Engineering and Science Advanced Research Institute of Fluid Science and Engineering Kyoto University Kyoto Japan

Contents of fly ash are important factors for the operation of coal-fired plants. Real-time monitoring of coal and fly ash such as unburned carbon in fly ash can be an indicator of the combustion conditions. Because of the strong signal intensity and the relative simplicity of the LIBS (Laser- Induced Breakdown Spectroscopy) technique, LIBS can be applicable for real-time composition measurement of coal and fly ash. This research presented here focused on the clarification of the effects of plasma temperature and coexisting materials on quantitative measurement of fly ash contents. Quantitative capability of LIBS was improved using the proposed plasma temperature correction method. The CO2 effect was also discussed to accurately evaluate unburned carbon in fly ash in exhausts. Using the results shown in this study, quantitative measurement of fly ash contents has been improved for wider applications of LIBS to practical fields.

关键词： Laser-Induced Breakdown Spectroscopy Fly Ash Temperature Correction CO2 Effect

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Influence of transient thermal response of solid wall on bubble dynamics in pool boiling

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Journal of Computational multiphase flows 2014年第3期6卷 313-327页

作者： Zhang, Liang Li, Zhen-Dong Li, Kai Li, Hui-Xiong Zhao, Jian-Fu Beijing100190 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi710049 China Beijing102209 China

Numerical simulation of single bubble pool boiling process including transient thermal response of solid wall is performed using the ghost fluid method and the level set method for the sharp interface representation. The results show that non-physical initial condition in the numerical simulation deeply affects the process of bubble growth, and then multi-cycle simulation is necessary to eliminate its influence. It is shown by the present results that two nucleate criteria, i.e. constant waiting time and constant nucleate superheat, for determining the appearance time for the subsequent bubble lead to the same quasi-steady process of bubble growth if they are matched with each other. A periodically expanding and receding thermal "hollow" can be observed inside solid wall underneath the growing bubble. The recovery of the temperature on the nucleate site and the thermal boundary layer near the heating surface is influenced by transient heat conduction inside solid wall, which can affect evidently bubble thermal dynamics and heat transfer.

关键词： Numerical methods

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Au@SiO_2 core/shell nanoparticle-decorated TiO_2 nanorod arrays for enhanced photoelectrochemical water splitting

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Chinese Science Bulletin 2014年第18期59卷 2191-2198页

作者： Jianan Chen Miao Yu Yuhao Wang Shaohua Shen Meng Wang Liejin Guo International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong University School of Chemical Engineering and Technology Harbin Institute of Technology

To improve the separation efficiency of photoinduced charge carries,Au@SiO2nanoparticles(NPs)with core–shell structure were loaded onto the surface of TiO2nanorods grown on fluorine-doped tin oxide substrate by a facile two-step *** resulted Au@SiO2/TiO2photoanodes were characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,as well as photoelectrochemical *** with pristine TiO2nanorod film,the Au@SiO2/TiO2films showed remarkable enhancement in photoelectrochemical water splitting,with incident photonto-current conversion efficiency increasing from 31%to37%at 380 nm at 0.7 V versus saturated calomel *** could be interpreted by the effect of metallic surface plasmon resonance of Au@SiO2NPs,which would generate an intense electromagnetic field with spatially nonhomogenous distributed *** a result,the charge carriers generated in the near-surface region of TiO2nanorods could be easily *** modification method based on the effect of metallic surface plasmon resonance for promoted charge carrier separation provides a promising way to develop semiconductor photoelectrodes with high solar water-splitting performance.

关键词：二氧化硅纳米粒子二氧化钛纳米棒电解水表面等离子体共振效应纳米颗粒金属 TiO2薄膜

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