核动力工程

Conceptual Design of Passive Moderator System for Thorium-Based Advanced CANDU Reactor

LIAN Hai-bo, ZHANG Xin, JIA Bao-shan

2007, 28(6): 1-3,8.

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A conceptual design which can meet the passive safety requirement is established in the study of the passive moderator system Thorium based Advanced CANDU Reactor （TACR）. In this design, the moderator cooling system （MCS） and the passive moderator residual heat removal system （PMRHR） are combined together for the first time. The steady operation during normal work of the reactor is analyzed by CATHENA Mod3.5c/Rev1, which provides a base for the verification of the design reliability.

Simulation Calculation for Equivalent Surface Source of 1# Radial Duct at Xi’an Pulsed Reactor

QUAN Lin, JIANG Xin-biao

2007, 28(6): 4-8.

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Monte Carlo code MCNP/4B and deep duct penetration skill of point detector and DXTRAN sampling had been used to calculate the radiation field parameter of 1# radial duct at Xi’an pulsed reactor. The parameters such as dose, flux, angular flux, spectrum of neutron and photon were obtained, and the veracity of results was confirmed through comparing the experiment with the theory. This calculation work proved the theory foundation for application and surface source’s simulation of this radial duct.

Study on Thermal Neutron Trap in Core of HFETR

FU Rong, PENG Feng, DENG Cai-yu, QIU Li-qing

2007, 28(6): 9-12.

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In this paper, the thermal neutron traps are studied for HFETR by transport method and diffusion method. The calculation results show that the best radius is 6.0cm for water thermal neutron trap and the maximal thermal flux is 3.1～3.7 times of the one in the non-trap core;and for beryllium-water thermal neutron trap, the best radius is 7.5cm（diffusion method） and 2.5cm（transport method）, respectively and the maximal thermal flux is 3.2～4.0 times of the one in the non-trap core.

Criticality Experiment for 2# Core of DF-VI Fast Neutron Criticality Facility

YANG Li-jun, LIU Zhen-hua, YAN Feng-wen, LUO Zhi-wen, CHU Chun, LIANG Shu-hong

2007, 28(6): 13-15.

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At the completion of the DF-VI fast neutron criticality facility, its core changed,and it was restarted and a series of experiments and measurements were made. According to the data from 29 criticality experiments, the criticality element number and mass were calculated, the control rod reactivity worth were measured by period method and rod compensate method, reactivity worth of safety rod and safety block were measured using reactivity instrument;the reactivity worth of outer elements and radial distribution of elements were measured too. Based on all the measurements mentioned above, safety operation parameters for core 2 in DF-VI fast neutron criticality facility were conformed.

Expanding of Reactor Power Calculation Model of RELAP5 Code

LIN Meng, CHEN Yu-qing, ZHANG Hong, LIU Ding-ming, YANG Yan-hua

2007, 28(6): 16-19.

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For better analyzing of the nuclear power transient in rod-controlled reactor core by RELAP5 code, a nuclear reactor thermal-hydraulic best-estimate system code, it is expected to get the nuclear power using not only the point neutron kinetics model but also one-dimension neutron kinetics model. Thus an existing one-dimension nuclear reactor physics code was modified, to couple its neutron kinetics model with the RELAP5 thermal-hydraulic model. The detailed example test proves that the coupling is valid and correct.

Benchmark Validation of DRAGON Program Using WIMS-D Nuclear Data Library

YANG Xue, SHI Gong, WANG Kan

2007, 28(6): 20-24.

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Through a series of benchmarks based on experiments, this paper validates the calculations of DRAGON3.05B with WIMS-D nuclear data library, and testes the correctness of its criticality and its isotope prediction and k_∞ in burnup calculation of various fuel materials and different lattices. By the comparison of the results of WIMSD-5B using WIMS-D and ENDF/B-VI.8, respectively, the result indicates that the calculation of DRAGON3.05B using WIMS-D is reliable and can satisfy the requirement of TACR design.

Experimental Research on Flow Instability in Vertical Narrow Annuli

WU Ge-ping, QIU Sui-zheng, SU Guang-hui, JIA Dou-nan

2007, 28(6): 25-28.

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A narrow annular test section of 1.5mm gap size and 1800mm heat length is successfully designed. The experiment has been conducted to investigate the characteristics of flow instability of forced convection in vertical narrow annuli. Distilled water is used as work fluid. The range of pressure is 1.0～3.0MPa and the mass flow rate is 3.0～25kg/h. Heat power is from 3.0 to 6.5kW and inlet fluid temperature is equal to 20, 40, and 60℃. It is found that the flow instability occurs in fixed inlet condition and heat power, when mass flow rate is below a certain value. The effects of inlet subcooling, system pressure and mass flow rate on the system behavior have been studied and the instability region is given.

Boiling Two-Phase Flow and Heat Transfer in Concentric Annular Tube

BAI Bo-feng, WANG Yan-chao, HUANG Rong, XIAO Ze-jun

2007, 28(6): 29-33,38.

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The boiling flow resistance and heat transfer characteristics is experimentally investigated under the outer tube wall heating condition in a concentric annular tube with 2.1mm gap size. The results show that the flow resistance in the annular tube is greater than that in circular tube, as well as the boiling heat transfer becomes enhanced. The heat transfer coefficient has close relationship with the pressure, thermal equilibrium quality, mass flux, heat flux, gap size of the annular tube, and heat models as well. The physical explanation about the enhancement boiling heat transfer in the annular tube is proposed with both micro-film evaporation mechanics and bubble disturbance mechanics. The correlations to calculate the flow friction coefficient and heat transfer coefficient are proposed based on the experimental data.

Analysis of Inner Flow Patterns in Gas-Liquid Ejectors

WU Wei-feng, FENG Quan-ke, XIANG Qing-jiang, LU Jun-xian

2007, 28(6): 34-38.

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The flow pattern in the choke of the horizontally installed gas-liquid ejector was studied. According to flow pattern criterion equations in horizontally installed pipes, and combining with the performance equation of gas-liquid ejectors, the transition intervals of annular flow and mist flow in the ejector were obtained. Further, the critical equation of annular flow in air-water ejector was discussed amply, and the relationship between the maximum local Mach number at the outlet of the nozzle and the inlet/outlet pressure ratio of the second fluid was obtained. A conclusion was deduced that the inner flow pattern in air-water ejectors was annular at least, when the gas （air） expanded supercritically in the nozzle.

Characteristics of Void Wave in Vertical Gas-Liquid Two-Phase Flows with External Disturbance

GU Han-yang, GUO Lie-jin, KUANG Bo, YANG Yan-hua

2007, 28(6): 39-42,47.

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Experimental investigation was carried out to study the characteristics of void wave for up-wards gas-liquid flow under external disturbances using double-ring conductance probes. The results show that the void wave exhibits the frequency selectivity to the periodical disturbances exerted. In the bubbly flow regime, low frequency external disturbances can induce void wave, whose frequency is almost equal to that of external disturbances. In the bubble-to-slug transition regime, low frequency external disturbances accelerate bubble coalescence and lead to bubble-to-slug transition. In the slug regime, however, external disturbances have little effect on the characteristics of void wave. Void wave velocity decreases first and then increases with the increasing of disturbance frequency. A critical disturbance frequency was found in the present experimental investigation. The effect of external disturbances on the void wave is most significant under the critical disturbance frequency. The critical frequency obtained in current experimental study was about 20 Hz.

Research on Dynamic Characteristics of New Chaotic-Advection Fins

KONG Song-tao, DONG Qi-wu, LIU Min-shan, ZHU Qing

2007, 28(6): 43-47.

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Analysis and the numerical simulation has confirmed that the flow is of the chaotic advection in the flow channel of the new fin. The chaotic advection results in stronger mixing under low Re, and thus enhances the heat transfer and anti-scaling ability. The new fin provides the beneficial exploration to the concept of chaotic advection which applies to the plate-fin heat exchanger.

Effect of Gap Width of Rectangular Narrow Channel on Heat Transfer Enhancement

HUANG Jun, WANG Qiu-wang, HUANG Yan-ping, BAI Bo-feng

2007, 28(6): 48-53.

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Considering the structural characteristics of flow passage in the rectangular narrow channel and the annular flow predicted analytical model of Critical Heat Flux（CHF） in round tube, the annular flow CHF analytical model in rectangular narrow channel has been obtained. This model can be used to predict the CHF of boiling two-phase flow annular flow in rectangular narrow channel which gap width is not less than 0.5mm. The analysis and calculation indicate that when the inlet width-gap width ratio of rectangular narrow optical channel is 25～85, the enhancement of CHF in channel is obvious. At the same time, considering the characteristics of two-phase flow, the new determinant laws of CHF in boiling two-phase flow system has been derived. The analysis and calculation indicate that this determinant laws is appropriate. The best width-gap width ratio of heat transfer enhancement is 45～75. Based on the above results, the reference width-gap width ratio of heat transfer enhancement is 45～75 in rectangular narrow channel.

Numerical Simulation of Flow Field and Temperature Field Near the Wall Region in a Rectangular Narrow Channel

XU Jian-jun, CHEN Bing-de, WANG Xiao-jun, XIONG Wan-yu

2007, 28(6): 54-57.

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Flow field and temperature field is very important for designing an optimized heated mode near the corner in a rectangular narrow channel, which is also one of the concerned problems of the deviser. To better understand the flow field and temperature field in a rectangular narrow channel, flow field and temperature field in a rectangular narrow channel were solved and analyzed. By the Computational Fluid Dynamics （CFD） code CFX, flow field and temperature field near the wall region in a rectangular narrow channel were obtained, and the effect of unheated region on flow field and temperature field was analyzed.

Effect of Inlet and Riser Sections on Two-Phase Flow Instability under Rolling

GUO Yun, QIU Sui-zheng, SU Guang-hui, ZHANG You-jia, JIA Dou-nan

2007, 28(6): 58-61,79.

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In this paper the two-phase flow instability of parallel channels system is studied under ocean conditions. The effect of inlet and riser sections under rolling motion is analyzed detailed. The parallel channel model based on the homogeneous flow model and the system equations are built by using control volume integrating method. The rolling motion model is also included. Gear method is used to solve the equations. The instability boundary under ocean condition is obtained. It is found that the instable regions occur both in low and high equilibrium quality regions. In high equilibrium quality the period-doubling phenomena are found.

Identification Method for Gas-Liquid Two-Phase Flow Regime Based on Singular Value Decomposition and Least Square Support Vector Machine

SUN Bin, ZHOU Yun-long, ZHAO Peng, GUAN Yue-bo

2007, 28(6): 62-66.

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Aiming at the non-stationary characteristics of differential pressure fluctuation signals of gas-liquid two-phase flow, and the slow convergence of learning and liability of dropping into local minima for BP neural networks, flow regime identification method based on Singular Value Decomposition （SVD） and Least Square Support Vector Machine （LS-SVM） is presented. First of all, the Empirical Mode Decomposition （EMD） method is used to decompose the differential pressure fluctuation signals of gas-liquid two-phase flow into a number of stationary Intrinsic Mode Functions （IMFs） components from which the initial feature vector matrix is formed. By applying the singular value decomposition technique to the initial feature vector matrixes, the singular values are obtained. Finally, the singular values serve as the flow regime characteristic vector to be LS-SVM classifier and flow regimes are identified by the output of the classifier. The identification result of four typical flow regimes of air-water two-phase flow in horizontal pipe has shown that this method achieves a higher identification rate.

Assessment of Graphite Oxidation in HTR-10

LUO Xiao-wei, YU Su-yuan

2007, 28(6): 67-70.

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Using a reasonable analysis model, the oxidation of graphite IG-11 used in 10MW High Gas Temperature Cooled Reactor （HTR-10） was investigated. In this paper, the oxidation quantity of reflector graphite by oxygen at maximum temperature in HTR-10 was calculated. The calculation results showed that the oxidation amount increased with the CO quanta in reaction product. When the reaction product was only CO, the maximum theoretical corrosion thickness of graphite was 35.8mm.When the reaction product was only CO₂, the minimum theoretical corrosion thickness of graphite was 23.7mm. During the service life of graphite, the oxidation of reflector graphite at maximum temperature was serious.

Evolution of Microstructure of Oxide Film of Nano-Crystalline Zircaloy-4

ZHANG Xi-yan, LI Cong, LIU Nian-fu, ZHANG Qiang, SHI Ming-hua, QIU Shao-yu

2007, 28(6): 71-75.

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In this paper the evolution characteristics of the microstructure of the oxide film of nanocrystalline zircaloy-4 have been studied with x-ray diffraction （XRD） technology. The oxide film is formed in water corrosion circumstance at 400℃. The results show that the evolution of the oxide film structure of nano-crystalline zircaloy-4 is similar to that of the normal zircaloy-4 with coarse grain size. However, the preferred orientation in nano-crystalline zircaloy-4 is found at low exponential plane, such as （101） and （102）. The grain size of the oxidation film of nano-crytalline ZrO₂ is smaller than that of the normal crystalline plane. The experimental results also show that the transformation speed rate from tetragonal phase （t-ZrO₂） to monoclinic phase （m-ZrO₂） in the oxide film of nano-crystalline zircaloy-4 is less than that in the oxide film of normal zircaloy-4 with coarse grain size. Thus, the nano-crystallized treatment can result in the changes of the corrosion dynamics process of the zircaloy-4 alloy. And these changes have been discussed in the paper.

Study on Compatibility between Al-Si and 1Cr18Ni9Ti

LAN Jun, CHA Wu-sheng, ZOU Cong-pei, LIU Gai-hua, WANG Zheng-yun

2007, 28(6): 76-79.

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The couple of Al-Si eutectic alloy and 1Cr18Ni9Ti stainless steel canister used in reactor was prepared by powder-metallurgy method. The compatibility and diffusion mechanics between them at 560℃ and 650℃ were investigated. The compatibility is greatly determined by diffusion temperature. At 650℃,SEM, EDS and XRD showed that the dramatic diffusion layer formed due to the infiltration and diffusion reaction. The Fe2Al5 has been found in the diffusion layer. At 560℃, there is a solid state reaction only between the Al-Si eutectic alloy and 1Cr18Ni9Ti.The diffusion layer is very thin, which has showed a very good compatibleness between them.

Performance Analysis of Passive Residual Heat Removal System under Blackout Accident of Chinese Integral Advanced Reactor

SHEN Jin, JIANG Guang-ming, TANG Gang, YU Hong-xing

2007, 28(6): 80-83.

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The residual heat removal system of Chinese Integral Advanced Reactor （CIP） designed by Nuclear Power Institute of China is of passive. In this paper, RELAP5/MOD is used to analyze and compute the core nuclear power, core average temperature, pressures of first and second loop and the PRHR power variation with time, and verifies the accident mitigation capability of the PRHR. The analysis results show that PRHR of CIP can successfully build the natural circulation and remove the core residual heat after the blackout accident.

Cooling Project Design for Magnetic Bearing of HTGR Helium Gas Turbine

WANG Yan, JIE Heng, ZHAO Lei

2007, 28(6): 84-86,109.

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Magnetic bearing is an important part of High Temperature Gas-cooled Reactor （HTGR） helium gas turbine. 4 cooling project designs are put forward for the high-temperature magnetic bearing of HTGR helium gas turbine. A three-dimensional model of magnetic bearing chamber is set up by GAMBIT, and analyzed by general computational fluid dynamic software——FLUENT. The simulation results show that the magnetic bearing chamber is cooled effectively by the improved design of cooling system, and its temperature is under control.

Plastic Limit Load of Elbows with Local Thinned Area under Combined Internal Pressure and In-Plane Closing Bending Moment

DUAN Zhi-xiang, SHEN Shi-ming

2007, 28(6): 87-91.

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Plastic limit load of elbows with local thinned area （LTA） under combined internal pressure and in-plane closing bending moment has been studied by finite element analysis （FEA） and experiments. The results of FEA and experiments show that,with different LTA, the variation of the limit load of elbows to the internal pressure is different. When a/b≤0.313, the limit moment of elbows always decreases with the increasing of the internal pressure. When a/b＞0.313, the limit moment of elbows increases with the increasing of the internal pressure and then decreases with the increasing of the internal pressure. By fitting the results of FEA, the safety assessment figure for elbows under combined internal pressure and in-plane closing bending moment is drawn. The safety assessment method using this figure is applicable for the engineer problems.

Development and Evaluation of Hybrid Fault Diagnosis System for Nuclear Power Plant

ZHANG Jian-de, YANG Ming

2007, 28(6): 92-96.

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A hybrid approach based on rule-based method and Artificial Neural Network （ANN） is proposed for on-line fault diagnosis of nuclear power plant. Rule-based method is used for identifying accident type and ANN is used for accurately estimating some information that is difficult to be diagnosed by rule-based method, such as accident location and severity level. Validity of the proposed method was verified by a simulation experiment in normal operation condition.

Research on γ-Heat in Core and φ63 Material Irradiation Channel of High Flux Engineering Test Reactor

DENG Cai-yu, QIU Li-qing, WANG Zhen-dong, JIA Dou-nan

2007, 28(6): 97-100.

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In this paper, γ-Heat distributions in the current High Flux Engineering Test Reactor core and in the φ63 material irradiation channel of HFETR were calculated with MCNP code. The results of the calculation and analysis showed that the γ-Heat power distribution in the current core is 3.29MW, the power of fuel element is 62.8MW, which is respectively 4.7% and 89.7% of the core total power （70MW）. Theγ-Heat power distribution of the unit flux media in threeφ63 irradiation channel is as follows:3.016W/g in G7, 3.733W/g in P12, and 3.627W/g in P15.

Countermeasures of Severe Accident in PWR

ZHANG Song, ZHUANG Wen-cui, ZANG Xi-nian

2007, 28(6): 101-104,116.

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The process and phenomena of the severe accident is described in this paper, and the severe accident management is analyzed. The WOG SAMG is systemically introduced, as well as its structure:the guidelines of MCR, the guidelines of TSC, CAs, and SAEGs. The logic of the accident management strategies of WOG SAMG is summarized and some suggestions for the research of accident management in China are provided.

Numerical Simulation of Effect of Different Hydrogen Production Rates on Hydrogen Distribution within Containment

CHENG Zhang-hua, CAO Xue-wu

2007, 28(6): 105-109.

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Flow characteristics of hydrogen gas in the containment is preliminarily studied by CFD code CFX. The result suggests that the basic trend of the hydrogen distribution is the same at various hydrogen release rates, and effects of different hydrogen production mainly on the hydrogen distribution are the different spiral formed when the hydrogen moves to the dome of the containment, the hydrogen kinetic energy would be lower and distribution area are larger and evener for the sequence with lower hydrogen release rate, and the hydrogen kinetic energy is higher and distribution area is more centralized in the higher hydrogen production rate accident.

Development of NPTC-11 Intelligence Control Instrument with Digital Display

WANG Cheng-ming, PU Li, XUE Yu-ping, ZHANG Bo, YU Jiang, CHEN Yong

2007, 28(6): 110-111,116.

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The accurate of the process control gauge has direct influence on the safe operation of nuclear power plants. Therefore it is necessary to accumulate experiences for the domestic development of this Instrument. In this paper, NPTC-11 intelligence control Instrument with digital display is developed based on the design code for nuclear Instrument, considering the actual application requirements and technical redundancy. Its application in nuclear power plant for almost one year indicates that this Instrument satisfies the development purpose and requirements.

Expansion of RELAP5 Control and Protection Simulation Functions with Simulinl

HOU Dong, LIN Meng, XU Zhi-hong, YANG Yan-hua, CHEN Zhi

2007, 28(6): 112-116.

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The RELAP5 itself is with the abilities to simulate nuclear power plants （NPP） control and protection systems. However, its simulation modeling are text-based, which is complicated and lacks of readability, and above all it is not suitable to model large complicated NPP control and protection systems. Simulink, which uses diagram-based modeling, however, is capable of modeling large complicated systems with high efficiency and convenience. This paper has coupled RELAP5 with Simulink, and also expanded the control and protection functions of RELAP5 with Simulink. To verify the coupling method, this paper has also compared the simulation results of the same NPP control and protection systems simulated by Simulink and RELAP5, respectively, and the comparison result has illustrated a good match between the two.

Nuclear Power Engineering Index

2007, 28(6): 117-128.

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2007 Vol. 28, No. 6