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Analysis of the loss of pool cooling accident in a PWR spent fuel pool with MAAP5

Annals of Nuclear Energy 2014年 72卷 198-213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

The Fukushima Daiichi nuclear accident shows that it is necessary to study potential severe accidents and corresponding mitigation measures for the spent fuel pool (SFP) of a nuclear power plant (NPP). This paper presents the analysis of loss of pool cooling accident scenarios and the discussion of mitigation measures for the SFP at a pressurized water reactor (PWR) NPP with the MAAP5 code. Analysis of uncompensated loss of water due to the loss of pool cooling with different initial pool water levels of 12.2 m (designated as a reference case) and 10.7 m have been performed based on a MAAP5 input model. Scenarios of the accident such as overheating of uncovered fuel assemblies, oxidation of claddings and hydrogen generation, loss of intactness of fuel rod claddings, and release of radioactive fission products were predicted with the assumption that mitigation measures were unavailable. The results covered a broad spectrum of severe accident evaluations in the SFP. Furthermore, as important mitigation measures, the effects of recovering the SFP cooling system and makeup water in SFP on the accident progressions have also been investigated respectively based on the events of pool water boiling and spent fuels uncovery. Based upon the reference case, three cases with the recovery of SFP cooling system and three other cases with makeup water in SFP have been studied. The results showed that, severe accident might happen if SFP cooling system was not restored timely before the spent fuels started to become uncovered; spent fuels could be completely submerged and severe accident might be avoided if SFP makeup water system provided water with a mass flow rate larger than the average evaporation rate defined as the division of pool water mass above the top of the spent fuel assemblies by the amount of time to start uncovering the spent fuel assemblies when no mitigation measures were taken. Although spent fuel assemblies were partly exposed due to the mass flow rate of

关键词： Spent fuel pool MAAP5 Loss of pool cooling accident Mitigation measures

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A-Novel-CdS-Nanorod with Stacking Fault Structures: Preparation and Properties of Visible-Light-Driven Photocatalytic Hydrogen Production from Water Splitting

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Energy Procedia 2014年 61卷 2450-2455页

作者： Kai He Liejin Guo International Research Centre for Renewable Energy & State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi 710049 China (Kai He will present the paper at the conference)

In the present study, CdS nanorod particles with the stacking fault structures were hydrothermally synthesized through a dissolution-recrystallization approach in concentrated ammonia solvent, for the first time. It was clear that concentrated ammonia solution contained a large number of hydroxyl ions and large numbers of ammonia. Comprehensive characteristics were performed to investigate the influence of stacking fault structures on the photocatalytic activity and stability of CdS nanorod particles. Transmission electron microscopy (TEM) images revealed that the CdS catalyst included many nanorods with stacking fault structures. Stacking fault structures were obviously observed within CdS nanorods with the length ranging from 70 to 200 nm and diameter ranging from 20 to 65 nm, respectively. It revealed that the formation of CdS nanorod particles with stacking faults was contributed to the dissolution-recrystallization process. There were many structural units for cubic phase changing to hexagonal phase in the CdS crystals in the process of hydrothermal resulting in forming a large number of stacking fault structures. Photo-generated electrons and holes migrating directionally along the nanorods direction and the stacking fault structures in some nanorods could promote the separation of photo-generated electrons and holes, which enhanced the activity of visible-light-driven photocatalytic hydrogen production. Through the photocatalytic hydrogen production experiments, CdS nanorod particles with the stacking fault structures showed much higher photocatalytic activity than CdS patticles prepared by the conventional hydrothermal method using the water as the hydrothermal solvent.

关键词： CdS Nanorods Stacking fault structures Photocatalytic hydrogen production

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FUNCTIONALIZED MODIFICATION TO G-C3N4 FOR EFFICIENT PHOTOCATALYTIC HYDROGEN GENERATION: ENHANCED OPTICAL ABSORPTION AND PROMOTED CHARGE SEPARATION

FUNCTIONALIZED MODIFICATION TO G-C3N4 FOR EFFICIENT PHOTOCAT...

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10th IUPAC International Conference on Novel Materials and their Synthesis NMS-X(IUPAC第十届新材料及其合成国际会议)

作者： S.SHEN J.CHEN International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi''an Jiaotong UniversityShaanxi 710049China

Metal oxide or metal nanodots modified g-C_3N_4 was fabricated using a facile evaporation-annealing method. The effect of metal oxide or metal nanodots decoration on the rate of visible-light (λ ＞ 420 nm) photocatalytic activity was studied by hydrogen production from triethanolamine (TEOA) aqueous solutions. The highest photocatalytic activity was observed on Cu(0.05wt%)/g-C_3N_4 with the hydrogen evolution rate of 241.3 μmolh~(-1)g~(-1), which exceeded that of pure g-C_3N_4 (141.6 μmolh~(-1) g~(-1) ) by more than 70%. The mechanism for the enhanced visible-light photocatalytic activity of g-C_3N_4 decorated with metal oxide or metal nanodots was carefully investigated. For the metal oxide nanodots decorated g-C_3N_4, the improved photocatalytic activity could be contributed to the promoted charge carrier transfer ability, as revealed by time-resolved photoluminescence emission decay spectra; for the metal nanodots decorated g-C_3N_4 (e.g. Ag@SiO_2/g-C_3N_4), the enhanced visible light absorption induced by plasmon effect greatly contributed to the improved photocatalytic activity for hydrogen production.

关键词： g-C3N4 optical absorption charge separation

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Experimental study on the vascular thermal response to visible laser pulses 15

Experimental study on the vascular thermal response to visib...

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15th International Heat Transfer Conference, IHTC 2014

作者： Li, D. Chen, B. Wu, W.J. Wang, G.X. He, Y.L. Ying, Z.X. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi710049 China Department of Mechanical Engineering University of Akron AkronOH44325-3903 United States Laser Treatment Center Department of Dermatology 2nd Affiliated Hospital Medical School Xi'an Jiaotong University Xi'an Shaanxi710004 China

Port Wine Stains (PWS) are congenital vascular malformations that progressively darken and thicken with age and laser therapy is most effective in clinical practice. Using dorsal skin chamber, this study evaluated thermal response of blood vessel to a 595 nm pulsed dye laser (PDL) with controlled energy doses and pulse durations. Totally 32 vessels (30∼300 μm in diameter) are selected from the dorsal skin of the mouse to match those in port wine stain. The experimental results showed that the thermal response of the blood vessels to laser irradiation can be recognized as coagulation, constriction with diameter decrease, disappearance, hemorrhage and collagen damage in the order of increasing laser incident fluence. Blood vessels with small diameter would response poor and survive from the laser heating because their thermal relaxation time is much shorter than the pulse duration. For PDL, vessel hemorrhage is the dominant thermal responses that appear in 15 of 32 blood vessels, and the consequent purpura can be used as treatment endpoint in clinical practice for 595nm PDL. The optimal incident fluence is from 10 to 12 J/cm2 under 6 ms pulse duration without considering the epidermal light absorption, while the optimal pulse duration is 6ms which is close to the thermal relaxation time of the blood vessels with average diameter of 110 μm.

关键词： Medical applications

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Understanding the Initial Decomposition Pathways of the n-Alkane/Nitroalkane Binary Mixture

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Chinese Journal of Chemistry 2013年第8期31卷 1087-1094页

作者： Yulei Guan Ying Zhang Chunhai Yi Bolun Yang Department of Chemical Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shannxi 710049 China

Addition of nitroalkanes into n-alkanes can lower the activation barriers of free-radical production and acceler- ate the decomposition of n-alkanes at relatively low temperatures. Four initial decomposition mechanisms of the n-butane/nitroethane binary mixture were proposed for the promoting effect and considered theoretically at the B3LYP, BB1K, BMK, MPW1K, and M06-2X levels with MG3S basis set. Energetics above was compared to high-level CBS-QB3 and G4 calculations. Calculated results confirm the feasibility of the four initial decomposition pathways：（I） the C--NO2 bond rupture of nitroethane to produce ethyl and .NO2, （II） HONO elimination from nitroethane followed by decomposition to .OH and .NO, （1II） rearrangement of nitroethane to ethyl nitrite which further dissociates into CH3CH20. and .NO, and （IV） direct hydrogen-abstraction ofnitroethane with n-butane.

关键词： free radical initial decomposition mechanism computational chemistry hydrogen-abstraction bimol-ecular

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Optimization of crucial parameters for double-layer microchannel heat sink

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2014年第3期35卷 567-570页

作者： Lin, Lin Chen, Yang-Yang Wang, Xiao-Dong School of Mechanical Engineering University of Science and Technology Beijing Beijing 100083 China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing 102206 China Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy North China Electric Power University Beijing 102206 China

As compared with single-layer microchannel heat sink (SL-MCHS), double-layer microchannel heat sink (DL-MCHS) can significantly improve the temperature uniformity of electric elements. This work uses a three-dimensional solid-fluid conjugate model incorporated with a progressive optimization procedure to optimize the cooling performance of a water-cooled, silicon-based DL-MCHS. Four geometric parameters (channel number N, bottom channel height Hc1, upper channel height Hc2, and vertical rib width Wr) and coolant velocity ratio of upper channel to bottom channel, t, are selected as optimized variables. The results show that at a fixed pumping power of 0.05 W and a heat fluxes qw=100 W·cm-2, the optimal geometric structure and coolant velocity ratio for the DL-MCHS are Nopt=70, Hc1,opt=200 μm, Hc2,opt=650 μm, Wr,opt=71.48 μm, and topt=1.85. The thermal resistance of the optimal DL-MCHS is reduced by 11.3% compared to the SL-MCHS, and the maximum temperature difference is reduced to 0.5 K, which is far less than 4.2 K of the SL-MCHS.

关键词： Heat resistance

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Enhanced photodynamic therapy of mixed phase TiO2（B）/anatase nanofibers for killing of HeLa cells

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Nano Research 2014年第11期7卷 1659-1669页

作者： Shuchao Zhang Dongjiang Yang Dengwei Jing Hongwei Liu Long Liu Yi Jia Meihua Gao Liejin Guo Ziyang Huo Department of Blood Transfusion the Affifiated Hospital of Medical College Qingdao University Oingdao 266003 China Department of Immunology Medical College of Qingdao University Qingdao266000 China Collaborative Innovation Centre for Marine Biomass Fibers Materials and Textiles of Shandong Province College of Chemical and Environmental Engineering Qingdao University Qingdao China Queensland Micro- and Nanotechnology Centre (QMNC) Griffith University Nathan Brisbane QLD 4111 Australia International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering College of Chemistry Chemical and Environmental Engineering Xi'an Jiaotong University Xi'an 710049 China Australian Centre for Microscopy and Microanalysis (ACMM) the University of Sydney Sydney NSW 2006 Australia

Photodynamic therapy （PDT）, which is a procedure that uses photosensitizing drug to apply therapy selectively to target sites, has been proven to be a safe treatment for cancers and conditions that may develop into cancers. Nano-sized TiO2 has been regarded as potential photosensitizer for UV light driven PDT. In this study, four types of TiO2 nanofibers were prepared from proton tri-titanate （H2T3O7） nanofiber. The as-obtained nanofibers were demonstrated as efficient photosensitizers for PDT killing of HeLa cells. MTT assay and flow cytometry （FCM） were carried out to evaluate the biocompatibility, percentage of apoptotic cells, and cell viability. The non-cytotoxicity of the as-prepared TiO2 nanofibers in the absence of UV irradiation has also been demonstrated. Under UV light irradiation, the TiO2 nanofibers, particularly the mixed phase nanofibers, displayed much higher cell-killing efficiency than Pirarubicin （THP）, which is a common drug to induce the apoptosis of HeLa cells. We ascribe the high cell- killing efficiency of the mixed phase nanofibers to the bandgap edge match and stable interface between TiO2（B） and anatase phases in a single nanofiber, which can inhibit the recombination of the photogenerated electrons and holes. This promotes the charge separation and transfer processes and can produce more reactive oxygen species （ROS） that are responsible for the killing of HeLa cells.

关键词： photodynamic therapy titanium oxides （TiO2） nanomaterials apoptosis mixed phase

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Effect of heavy metal ions on the hydrogen production performance of Rhodobactersphaeroides HY01

Effect of heavy metal ions on the hydrogen production perfor...

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第十五届全国氢能会议暨第7届两岸三地氢能研讨会

作者： Honghui Yang Hongyu Ma Lingdi Li Hao Xu Wei Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049P.R.China Department of Environmental Science & Engineering Xi'an Jiaotong UniversityXi'an 710049P.R.China

A newly isolated photosynthetic bacterium,Rhodobactersphaeroides HY01 showed high hydrogen production performance(*** Energy39,10051-60)and good flexibility on genetic modification(*** Energy 39,14633-41).In order to investigate its potential on using wastewater containing heavy metal ions for photosynthetic hydrogen production,four conventional heavy metal ions,Pb2+,Cu2+,Cr6+ and Cd2+ were studied for their effects on the photosynthetic hydrogen production performance of Rhodobactersphaeroides HY01.

关键词： photosynthetic hydrogen production heavy metal ions Rhodobactersphaeroides HY01

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The Advances of Post-combustion CO 2 Capture with Chemical Solvents: Review and Guidelines

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Energy Procedia 2014年 63卷 1339-1346页

作者： Xiaomei Wu Yunsong Yu Zhen Qin Zaoxiao Zhang School of Chemical Engineering and Technology Xi’an Jiaotong University No.28 Xianning West Road Xi’an 710049 P.R. China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road 710049 P.R. China

Carbon dioxide is the major greenhouse gas that contributes to the global warming more than 60%. Carbon dioxide from power plants is one of the main sources. Therefore it is essential to reduce the CO 2 emission from power plant flue gas. Post- combustion carbon capture is the optimal choice in near-to meddle-term, since it does not need to change the configuration of the power plants essentially. Chemical absorption with amine-based solvents is currently the state-of-the-art technology for post- combustion carbon capture. This paper introduces the typical CO 2 amine absorption process and analyses the main problems during the absorption process. To make the process more efficient, several improvements were investigated: increasing gas-liquid contacting area, searching for new type of reactant, and dilution of the aqueous fraction with organic liquids. The present study aims to summarize the improvements in amine scrubbing process for CO 2 capture and forecast the promising research directions in the future.

关键词： CO 2 emission post-combustion capture chemical absorption absorbents

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Single-jet Spray Mixing with a Confined Crossflow

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Chinese Journal of Chemical engineering 2013年第1期21卷 14-24页

作者：孙慧娟白博峰严俊杰张海滨 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

In order to achieve uniform mixing between spray droplets and crossflow, cold-model experiment of a hollow-cone water spray in an air crossflow is investigated via a numerical simulation. The simulation cases are designed by using the orthogonal design method. The Eulerian-Lagrangian formulation is employed for modeling the droplets-crossflow two-phase flow while the realizable k-ε turbulence model is used to describe the turbulence. A new index, mixedness quality, is proposed to assess the overall mixing of the droplets in the crossflow. The simulation results demonstrate that the counter-rotating vortex pair (CVP) imposes a more significant impact on the spatial distribution than on the size distribution of the droplets. Pairs of CVP with smaller scales are preferable for achieving a better mixing. The influencing factors are listed in the following order in terms of the degree of their impact from the greatest to the least: the Sauter diameter of the initial droplets, the mixing tube diameter, the spray angle, the velocity of the inlet crossflow, and the vertical velocity of the initial droplets. A moderate droplet diameter, a smaller tube diameter, a moderate spray angle, a greater crossflow velocity and a moderate vertical velocity of the droplet are favorable for achieving a higher mixedness quality of the jet spray in a confined crossflow.

关键词： mixing jet spray droplets crossflow numerical simulation

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