核动力工程

Thermal Hydro-Mechanical Analysis of Reactor Vessel Cooling System under Station Blackout Accident

QIAO Xue-dong, YANG Hong-yi, FENG Yu-heng

2006, 27(S1): 1-4,22.

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Reactor vessel cooling system is one of the important auxiliary systems in the primary system of China experimental fast reactor（CEFR）,which can cool the reactor vessel in various conditions.the reactor cooling system during the station blackout accident.It provides the data for the mechanical analysis,and the theoretical support to the optimum design and safety analysis of the fast reactors.

Analysis of Small Break LOCA for ACR-700 NPP

ZHENG Li-min, SHEN Sen

2006, 27(S1): 5-8,72.

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Analysis of a small break loss of coolant accident（SB-LOCA） for the latest design of ACR-700 PHWR nuclear power plant（NPP） developed by Atomic Energy of Canada Limited has been performed with CATHENA MOD 3.5d,a PHWR system thermal-hydraulic analysis code based on the analysismodel established.The limiting break size has been found by performing the sensitivity study for three different break locations [i.e.reactor inlet head（RIH）,HTS pump suction（PS） pipe and reactor outlet head（ROH）] under the limiting case（i.e.SB-LOCA with subsequent loss of class Ⅵ power with all safety system available）,and main analysis results were also provided.

Safety Analysis for Xi’an Pulsed Reactor in Pulse Operation Mode with the Core in Steady Arrangement and Design Project for the New Core Arrangement

CHEN Li-xin, CHEN Wei, ZHANG Ying, JIANG Xin-biao, ZHAO Zhu-min

2006, 27(S1): 9-12,17.

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Through the theoretical calculation of the safety parameters of Xi’an Pulsed Reactor,this paper analyzes the feasibility when the steady arrangement core runs in pulse mode.Based on the original design of steady arrangement core,the paper also gives two kinds of new core arrangements of Xi’an Pulsed Reactor.It calculates the physics parameters,safety parameters and the parameters of experimentation channels of this two kind of design projects.This work may be a reference for the simplification of the refueling program,improving the parameters of the certain channel and reducing the probability of failed fuel rod clad-ding.

Computational Analysis of Environment Condition Inside Containment under Severe Accident

CHEN Song, LIU Xin, SHI Guo-bao, ZHU Xin-guan, CAI Jian-ping

2006, 27(S1): 13-17.

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Considering the detail requirements of evolutionary and advanced light-water reactor design and taking the mitigation measures for severe accidents in Chashma Nuclear Power Plant（NPP） Unit-2 as an example,this paper analyzed the severe accident sequences affecting the environment conditions inside containment such as the large LOCA with safety injection failure,small LOCA with safety injection failure and Station Blackout with AFW failure,and its mitigation measures..The results show that the containment pressure and temperature are decreased obviously after the containment spray is recovered.As a result,the environment condition inside containment comes to available for the equipment.

Analysis of Hydrogen Distribution and Control in NPP Containment during Severe Accidents

FANG Li-kai, CHEN Song, ZHOU Quan-fu

2006, 27(S1): 18-22.

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CONTAIN code was used to calculate the hydrogen distribution in the containment of 1000 MW NPP during severe accidents in this article.Two sequences of severe accidents were selected in the system shall be designed to meet the requirement of safety review and to improve the safety of 1000 MW NPP.analysis: the first was large break LOCA in cold leg with ECCS（emergency core cooling system） failure;and the second was SBO with failure of emergency feed pump driven by turbine.The results showed that different hydrogen control requirements are needed for different accidents in various compartments.Hydrogen control

Analysis of Flow Field in Hot Gas Chamber of the High Temperature Reactor

WANG Jin-hua, BO Han-liang, JIANG Sheng-yao, HUANG Zhi-yong

2006, 27(S1): 23-29.

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This study used the Computational Fluid Dynamics（CFD） program CFX5 to calculate the flow in the hot gas chamber and the hot gas duct in high temperature reactor,on the basis of the experimental research.The calculated results including velocity flow field,pressure field and temperature field were ob-tained,which could be a reference for the design and experimental research of the hot gas chamber of the high temperature reactor.The numerical simulation results indicated that the gases in the hot gas chamber mixed intensively,which accelerated the heat transfer for the gases with different temperatures,and which was in favor of the temperature mixing for high temperature and low temperature gases.In the ribs area,the gas mixing is not so intensive,which had negative effect on the heat transfer between gases with different temperatures.The temperature mixing rate in the hot gas duct increased with the increase of the hot gas duct,and when the length of the hot gas duct was more than 2.5 m,the temperature mixing rate was above 99%.

Transient Thermal Analysis for Safety of Test Blanket Module for ITER

BO Yun-qing, WU Yi-can, CHEN Hong-li

2006, 27(S1): 30-33.

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Based on analyses of the Dual Functional Lithium Lead-Test Blanket Module（DFLL-TBM） submitted to International Thermonuclear Experimental Reactor（ITER） Test Blanket Working Group（TBWG）,the influence to ITER safety was evaluated by analyzing the typical transient accidents related to DFLL-TBM system.The transient accidents include invessel TBM coolant leaks,in-TBM breeder box coolant leaks and exvessel TBM coolant leaks.The results show that DFLL-TBM has the ability to remove the decay heat by thermal radiation when transient accidents occur,and the structures of the TBM would not melt.The DFLL-TBM can meet the ITER safety requirements on thermal aspect.

Study on Depressurization Efficiency of Pressurizer Relief Valves

JI Duan, CAO Xue-wu, CHE Ji-yao

2006, 27(S1): 34-37.

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Based on SCDAP/RELAP5/MOD3.1,which may simulate the detail severe accident transient mechanism,this paper analyzes the progression and depressurization efficiency of postulated ATWS accident,initiated by the loss of main feed water（LOFW）,the loss of offsite power（LOOP） and uncontrolled rod cluster control assembly（RCCA） bank withdrawal.The results show that one train of pressurizer relief valves（PRV） is not sufficient to depressurize reactor coolant system（RCS）,and the primary pressure still remains above 10MPa;it brings a great potential risk of high-pressure core melt.The case adding one more train of PRV is analyzed and the results show that two trains of PRV could adequately reduce the primary pressure to about 3MPa,and the safety injection starts up and arrests the core melt progression,and thus reduce the risk of high-pressure core melt.It is also showed that the high pressure injection system has important contribution to RCS depressurization.

Study of Steady and Transient Characteristics of New Nitrogen-Typed Pressurizer

ZHANG Da-lin, QIU Sui-zheng, GOU Jun-li, JIA Dou-nan

2006, 27(S1): 38-42.

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Based on the basic theoretical model of nitrogen-typed pressurizer,this paper analyzed the steady and transient characteristics of the pressurizer,and the variations of the pressure,water level,water enthalpy,water mass,nitrogen temperature,nitrogen volume with the change of time are predicted using the model under two different fluctuation flow rate.It is found that,when fluctuating flow is positive,the pressure,water region mass,enthalpy,water level and nitrogen temperature all increase,while nitrogen volume decreases.When fluctuating flow is negative,the characters of nitrogen-typed pressurizer are opposite.In addition,the time response of nitrogen-typed pressurizer is very good.Furthermore,the effects on the steady and transient characteristics of main parameters as well as the experimental verification should be carried out in the future.

Characteristic of Fuel Assemblies and Analysis of Fuel Rod Bowing of WWER-1000

YAO Jin-guo

2006, 27(S1): 43-46,52.

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Based on the design characteristics of WWER-1000 type reactor and the operation practice,this paper describes the characteristics of the fuel assembly of WWER-1000 and compares with PWR in western countries.Especially,this paper analyzes the bowing performance of the fuel assembly of WWER-1000 and the bowing influence on the thermo-hydraulics and fuel assembly design,and clarifies the experimental results of the bowing effect on the critical heat flux density（CHF）,which confirms that the performance of WWER-1000 fuel assembly in the entire operation life can be guaranteed.

Analysis of Characteristic Curves for Natural Circulation Flow Excursion at Low Steam Quality Conditions

YANG Xing-tuan, JIANG Sheng-yao, ZHANG You-jie

2006, 27(S1): 47-52.

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Natural circulation flow excursion has been observed on the test loop HRTL-5 under low steam quality conditions,which simulates the geometry and system design of the 5MW full power natural circulation Nuclear Heating Reactor.By means of a Four-Equations-Drift-Flux Model,which has considered the sub-cooled boiling,condensation and void flashing,the computational codes have been developed,from which the natural circulation characteristic curves and its operation curve have been obtained,and the bifur-cation curve and the static instability boundary have been determined.Therefore the Method of Characteristic Curves Analysis has been presented.Analytical results show that the Characteristic Curves Analysis Method is the effective approach to study the natural circulation static flow instability;Decreasing the heat flux or outlet two-phase resistance,and increasing the system pressure or inlet single-phase resistance are useful to avoid the natural circulation flow instability.

Analysis of System Instability Phenomena of Flow Pulsating Test in Parallel Channels

ZHUO Wen-bin, WANG Fei, XIAO Ze-jun

2006, 27(S1): 53-56.

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The phenomena,including the water hammer and hydraulic pulsation with same phase,appear in the test of flow pulsation in parallel channels.These phenomena are discussed in this paper.The mixing condensator in the loop is the source of flow pulsation,and the means of flux and the range of pulsatile flow based on the Venturi tube in pulsatile flow condition should be corrected with propriety.

An Investigation on Heat Transfer Characteristics of Fully Developed Flow in Bilaterally Heated Narrow Annuli

ZENG He-yi, QIU Sui-zheng, JIA Dou-nan

2006, 27(S1): 57-60,64.

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Numerical research was carried out on the convection heat transfer characteristics in bilater-ally heated annular channel with narrow gap under the conditions of fully developed flow,where the inner and outer walls are heated by uniform but unequal heat fluxes.Calculation results show that the ratio of the inner wall heat flux to the outer wall heat flux has great effects on the heat transfer characteristics in bilater-ally heated narrow annuli.With the increase of the inner wall heated flux,the heat transfer coefficient at the outer wall of the inner tube will decrease,while the heat transfer coefficient at the inner wall of outer tube will increase.These numerical results are in good agreement with some experimental results in open litera-tures.Numerical results also show that the decrease of the annuli gap will yield heat transfer deterioration during flowing in narrow annular channels.

Preliminary Visualization Study of Onset of Bubble Sliding in Sub-Cooled Boiling in Rectangular Narrow Channel

HE Jun-shan, CHEN Jun, JIANG Xu-lun, ZHAO Hua

2006, 27(S1): 61-64.

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To understand the onset of bubble sliding（OBS） in sub-cooled boiling flow in a rectangular channel,a visualization study has been conducted using a high-speed digital camera system.The results show the OBS distribution in the heating plate is with the obvious parabola-shape,and the mass velocity,the heat flux and the pressure have greater effect on the distance of OBS.

Design of Critical Heat Flux Test Section for Non-Uniform Axial Power Shapes in Rectangle Narrow Channel

XIONG Wan-yu, WANG Fei, MA Jie-liang

2006, 27(S1): 65-67,82.

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Test section design,test techniques and test data processing are one of the key technologies of test research of CHF for non-uniform axial power shapes in rectangle narrow channel.However,the design of test section is critical for this test research.Therefore,it is very important to accurately design the test section for test research of CHF for non-uniform axial power shapes in rectangle narrow channel.Design method and result of CHF test section of rectangle narrow channel has been presented.During the test,the electric heating has been adopted,and the non-uniform heating has been realized by changing the wall thickness along axial direction.The Measurement and insulation method of the experimental assembly has also been described.

Method of Determining the Transition Boundary of Slug Flow to Churn Flow in Vertical Tubes

CAO Xia-xin, YAN Chang-qi, SUN Li-cheng, SUN Zhong-ning, HUANG Wei-tang

2006, 27(S1): 68-72.

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Experimental studies on determining the transition boundary of slug flow to churn flow are pressure and friction loss,the turning point of inside pressure curve is just the point where the churn flow takes place.According to the experimental data,the transition boundaries of slug flow to churn flow in two carried out in two tubes,which inside diameters are 15mm and 25mm,respectively.The results show that during the transition,the inside pressure experiences the changeable process from decrease to increase with the increase of the air flow rate.Based on the visual observation and the theoretical analysis of the inside different tubes are given.

Vapor Bubble Behavior in Sub-Cooled Flow Boiling in Vertical Annular Ducts

SUN Li-cheng, YAN Chang-qi, SUN Zhong-ning

2006, 27(S1): 73-76.

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In the boiling heat transfer setup,the two commonly methods to heat the test section wall are electric heating and fluid heating,and the boiling heat transfer for the latter is seldom studied.The boiling heat transfer characteristics under the two heat methods are different.Visualization research has been conducted on the bubble behavior of sub-cooled flow boiling water in vertical annular ducts heated by water.The duct widths are 5mm and 3mm,and the mass flux ranges are 16.8～55.3 kg/（m².s） and 15.3～62 kg/（m².s）,respectively.The results show that there exists a bubble layer near the wall,and most bubbles move in the layer.Most bubbles in 3mm annulus will slide for a distance not more than 2～3 times of the bubble diameter and keep expanding and shrinking for several times before departure.On the contrary,most bubbles in 5mm duct scarcely slide and are always bounced to the wall after departure.All these bubble behavior should be one of the reasons that the boiling can enhance heat transfer greatly.

Research Progress on Flow and Heat Transfer in Porous Media

YAN Xiao, XIAO Ze-jun, HUANG Yan-ping, WANG Fei

2006, 27(S1): 77-82.

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Flow and heat transfer in porous,which is one of the most interested issues in the engineering thermo-physics,is frequently encountered in many fields of science and engineering.In this paper,research progress on the criterion for different flow regimes,correlation for the prediction of flow press drop,heat transfer enhancement and the thermal equilibrium assumption between solid matrix and fluid in porous media with internal heat source is reviewed.Based on the characteristics of flow and heat transfer in porous media,the potential applications in thermal hydraulic of nuclear reactor in China are suggested.

Evaporation Drag Model of High Temperature Particles Moving Inside Coolant

HU Zhi-hua, KUANG Bo, YANG Yan-hua

2006, 27(S1): 83-85,98.

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A thin layer vapor film due to the rapid evaporation of liquid around the particles in the coarse mixing stage surrounds high temperature particles.The flow in the boundary layer around the high temperature particles is greatly different from the flow without evaporation,and then the general drag model of particles in room temperature cannot be adopted in this situation.In this paper,considering the forces distribution and surface evaporation effect,an evaporation drag model for one high temperature particle moving inside coolant is proposed based on the analysis of acting forces on the particle.It is theoretically indicated that the thickness of the vapor film has great effects on the drag force.In the beginning of vapor film growing,the evaporation drag is always much larger than that in general conditions except the relative velocity is very high.The calculation results prove that unless the initial film thickness or the relative velocity is very large,the inner evaporation drag should be taken into account at high temperature conditions.

Parametric Study on Bubble Collapse in the Finite Depth Liquid

XU Cheng-jie, BAI Bo-feng, WANG Xian-yuan, LIU Hong-yun

2006, 27(S1): 86-90,98.

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Based on an improved mathematical physical model of bubble collapse in the finite depth of liquid caused by an initial bubble wall motion,the effect of fluid viscosity,initial bubble wall motion,height height of liquid affects hardly the criteria of bubble collapse if it is 100 times more than the initial radius of the bubble,which can be considered as the bubble staying in the infinite depth of liquid.It is difficult for the bubble to collapse if the initial bubble wall velocity is of 0m/s.On the contrary,it is easy for the bubble to vance.

Nonlinear Characteristics of Two-Phase Natural Circulation and Its Experimental Investigation

LIU Xiao-jing, KUANG Bo, CHEN Hong, XU Ji-yun, WANG Tao, SUN De-xiang, JIANG Xu-lun

2006, 27(S1): 91-98.

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Based on experimental investigation and bifurcation analysis on two-phase natural circulation system,certain nonlinear mechanisms of the system,especially static bifurcation features and hysteresis effect,are verified and discussed in this paper.Study of time series of the dynamic parameters is carried out in both time and frequency domains,with boiling eruption induced relaxation instability mechanism under certain conditions being suggested and investigated.Further,through the phase space reconstruction of relating time series and fractal analysis,discussion to nonlinear evolution of the system with varying heating power is delivered.

Hydraulic Experimental Research of New Type Heat Exchanger

WANG Sheng, XIAO Ze-jun, HU Jun, HUANG Zhao-qing, LI Hua-qi

2006, 27(S1): 99-101,106.

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New type heat exchanger consists of five cell subassemblies. Hydraulic experiment of new type heat exchanger is divided into two parts: separated effect experiments and integral hydraulic simulation experiments. The separated effect experiments simulate four kinds of passages, from which the correlations of pressure drop is obtained. Simulation scale of integral hydraulic simulation model is 1:1, and some components is simplified. By the experiments, flow rate distribution of the primary side and resistance coefficients of the different components are determined. All data obtained have been used to improve the design of new type heat exchanger.

Experimental Study of Heat Transfer and Flow Resistance Characteristics for Shell-and-Tube Heat Exchangers with Continuous Helical Baffles

ZENG Min, PENG Bo-tao, YU Peng-qing, CHEN Qiu-yang, WANG Qiu-wang, HUANG Yan-ping, XIAO Ze-jun

2006, 27(S1): 102-106.

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This paper investigated the flow and heat transfer characteristics for shell-and-tube heat exchangers with continuous helical baffles and segmental baffles. The resistance factor and heat transfer correla-tions for shell-side regions have been obtained. The comparison among heat transfer exchangers with continuous helical baffles, segmental baffles and non-continuous helical baffles has been made, and it is found that the heat exchangers with continuous helical baffles is superior to the heat exchangers with segmental baffles and non-continuous helical baffles when the shell-side velocity increased.

Experimental Research on Hydraulic Resistance of Throttle Set with Special Structure under Non-Isothermal Condition with Single-Phase Water

MA Jun, ZHUO Wen-bin, CHEN Bing-de

2006, 27(S1): 107-110.

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Experiments were done to examine the effects of geometric and operational parameters on the hydraulic resistance of throttle set,and the experimental parameters were as follows: flow rate ranged from 1.5 to 33 kg/h,inlet fluid temperature from 20 to 70℃,and pressure from 1.8 to 2.4 Mpa,respectively.An empirical equation for hydraulic resistance was obtained after the effects of pitch number of throttles,throat diameter,temperature,pressure,flow rate and outside heat source on the hydraulic resistance of throttle set were examined.The results indicated that the pitch number,throat diameter,flow rate and temperature has great effect on the resistance of throttle set;when the inlet temperature was constant,the effect of external heat flux on the resistance was considerable;the higher the heating power was,the higher the temperature rise between inlet and outlet was,and the less the resistance was.

2006 Vol. 27, No. S1