核动力工程

Calculation and Characteristic Analysis of Ex-Core Detector Spatial Response Function for High Temperature Gas-Cooled Reactor

ZHOU Xu-hua, LI Fu, CAI Qi, HAN Ren-yu

2011, 32(6): 1-6.

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Abstract:
The calculation model of ex-core detector spatial response function for the High-Temperature gas-cooled Reactor-Pebble-bed Module（HTR-PM） is constructed.Based on the adjoint transport theory,the ex-core detector spatial response function is calculated by the Monte Carlo method program（MCNP） and 3D discrete ordinate method program（TORT）.The characteristic analysis of ex-core detector spatial response function and comparison of these two results indicates that the result of 3D discrete ordinate method program accords with that of Monte Carlo method program,the adjoint transport theory is appropriate to construct the relationship of ex-core detector reading and in-core power distribution which is named as detector spatial response function,and the reading of ex-core detector is mainly contributed by the high energy group neutrons of the region facing to ex-core detector.

Improvement of Accuracy of Resonance Self-Shielding Calculation Based on Subgroup Method

HUANG Shi-en, WANG Kan, YAO Dong

2011, 32(6): 7-12.

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Based on the neutron self-shielding calculation code SGMOC,which is the combination of subgroup method and characteristics method that developed by ourselves,we studied the two techniques to improve the SGMOC calculation accuracy.The numerical results prove that both techniques have the capability to improve the resonance self-shielding calculation accuracy.The resonance interference effect treatment which uses a new method to obtain the conditional probabilities,has a correction effect about 20~230 pcm.When the impact of the resonance scattering is considered,the correction effect is about 100 pcm.When utilizing the above two techniques simultaneously,the correction effect is about 30~270 pcm.

Design and Experimental Research of General Passive Fluid Controlling Cell

HAN Xu, ZHENG Ming-guang, YU Yi-qi, YE Cheng

2011, 32(6): 13-16,46.

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The present experimental research is focused on the use of GPFC in LPP PCS.It is proved that GPFC is reliable enough to keep effective and precise controlling in PCS spraying.

A Methodology for Analysis of Dependency between Operators in Digital Control System in a Nuclear Power Plant

LI Peng-cheng, DAI Li-cao, ZHANG Li, CHEN Guo-hua, ZHAO Ming

2011, 32(6): 17-22.

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The dependence between actions of the operators is more prevalent in the digital control system.Fuzzy logic-based approach is provided to evaluate the dependence of operators’ actions.Firstly,through the analysis of the characteristics of human factors in the digital control system,the factors influencing the dependence level of operators’ actions are identified,and the analytical model of dependence is constructed.Then,the methodology for analysis of dependency between actions of the operators is established based on the fuzzy logic approach.This method can not only simulate the vague and uncertain knowledge,but also give a clear explanation of the origin of the results and its reasoning process by tracing the reasoning steps.There-fore,there is traceability and repeatability in the proposed method.

Research on Fault Diagnose and Fault Tolerant Control of Steam Generator Based on Strong Tracking Filter

ZHANG Wei, DENG Zhi-hong, XIA Guo-qing, CAI He-gao

2011, 32(6): 23-27.

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In order to further improve the safety of nuclear power plants,based on the nonlinear system with stochastic noise,the strong tracking filter is used to evaluate the sensor fault bias of steam generator control system and reconstruct the sensors output to implement the fault tolerant control.The simulation results demonstrate that this method can evaluate the time-varying sensor fault bias effectively and has great fault tolerant ability,and the methodology employing the strong tracking filter for steam generator fault tolerant control design is effective.

Research on Application of Active Disturbance Rejection Control Based on Adaptive GA in Water Level Control of Steam Generator

WANG Ming-mei, CHENG Qi-ming, WANG Ying-fei, HU Xiao-qing

2011, 32(6): 28-33.

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The steam generator of nuclear power plant is a nonlinear,time-varying system.Application of the active disturbance rejection control method in the water level control of steam generator can solve the contradiction between speed and overshoot in the conventional PID control system,and it also can compensate the internal and external disturbances of the object model dynamically.However,ADRC parameters are numerous and without uniform adjustment specification,and are very difficult to be tuned.In order to over-come the difficulties in the parameter tuning of the ADRC,the adaptive genetic algorithm is used to tune ADRC parameters.The simulation results show that its robustness and its control quality are better than those of the traditional cascade PID control.

Experimental Study on Pool Boiling Critical Heat Flux in Inclined Confined Spaces

WEN Qing-long, CHEN Jun, ZHAO Hua

2011, 32(6): 34-37.

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CHF experiments in confined spaces are performed for near-saturated demineralized water at atmospheric pressure with gap sizes of 3 mm,5 mm and 8 mm,and inclination angles of 0°,5°,10°,15°,20°,and 30°.Analysis of CHF data showes that CHF decreases as the inclination angle changes from 30° to full downward facing position（0°） and increases as the gap size varies from 3 mm to 8 mm.In the present study,certain transition angles are also identified for different gap sizes.For the gap sizes of 3 mm,5 mm and 8 mm,the transition angles are found to be 10°,15° and 20°,respectively.

Analyses on Flow Instability of Passive Residual Heat Removal System for CPR1000

ZHANG Ya-pei, TIAN Wen-xi, QIU Sui-zheng, SU Guang-hui

2011, 32(6): 38-41.

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The CPR1000 Passive Residual Heat Removal（PRHR） System were investigated using RE-LAP5/MOD3.4 under the condition of Station Blackout（SBO）.The flow instability of SG secondary side was affected by the arrangement of the air-cooled heat exchanger and the height of the cooling tower.The calculation results showed that the horizontal layout of the air-cooled heat exchanger could reduce the flow instability obviously,and the instability decreased with the increase of the cooling tower.The results also showed that the PRHR of CPR1000 could remove the core residual heat after the SBO to ensure the safety of the reactor.

Theoretical Analysis of Efficiency and Resistance of Glassfiber Filter Media in Helium Gas

ZHANG Zhen-zhong, JIANG Feng, YU Tao, YE Sui-sheng

2011, 32(6): 42-46.

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In the air and helium gas,based on MPPS and Sodium flame methods,this paper calculates the filtration efficiency and resistance of three levels of HEPA filter media.The results show that comparing with the air,in helium gas,filter media have lower resistance and higher efficiency,and secondly,at the same filtration rate and particle diameter,with the rise of environment temperature,the filter media have higher resistance and efficiency.

Effect of Layout on Surge Line Thermal Stratification

LAI Jian-yong, HUANG Wei

2011, 32(6): 47-50,95.

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In order to analyze and evaluate the effect of layout on the thermal stratification for PWR Pressurizer surge line,numerical simulation by Computational Fluid Dynamics（CFD） method is taken on 6 kinds of layout improvement with 2 improvement schemes,i.e.,increasing the obliquity of quasi horizontal section and adding a vertical pipe between the quasi horizontal section and next elbow,and the maximum temperature differences of quasi horizontal section of surge line of various layouts under different flowrate are obtained.The comparison shows that,the increasing of the obliquity of quasi horizontal section can mitigate the thermal stratification phenomena but can not eliminate this phenomena,while the adding of a vertical pipe between the quasi horizontal section and next elbow can effectively mitigate and eliminate the thermal stratification phenomena.

Numerical Study on Flow and Heat Transfer Characteristics with Low-Reynolds Number in Micro-Wavy Tubes

ZHU Sheng, SUN Zhong-ning, FAN Guang-ming

2011, 32(6): 51-55.

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The flow and heat transfer characteristics of three different micro-wavy tubes with different configuration parameters（the curve radius is 32 mm,and the curve angles are 45°,60° and 75°,respectively） in low-velocity（0.0033m/s≤u≤0.05m/s） flow are considered,using software Fluent for computing fluid dynamics.The results show that the curve angle plays an important role in the flow and heat transfer characteristics of micro-wavy tubes.The Nu numbers and friction coefficients f are much larger compared with that of straight tube with the same diameter,f increases when the amplitude ^A becomes larger and the ratio of μplays a decisive role in Nu numbers.When 20≤Re≤300,the Nu number and the friction coefficient f are in-creased by as much as 166.3% and 52.6%,respectively.

Effect of Channel Size on Turbulent Flow in Tight Lattice

YAN Bing-huo, GU Han-yang, YU Lei

2011, 32(6): 56-60,65.

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The turbulent flow in 37 rod bundles is investigated with CFD code FLUENT.The calculation results are validated with experimental data at first.Then the effects of diminishing rod-rod gap size on turbulent mixing and coherent structure in tight lattice are analyzed.As the P/D decreases,the large scale coherent structure becomes more significant,and the resulted transverse momentum and energy exchange become more obvious.When the critical pitch to diameter ratio is about 1.03,the heat transfer in this kind of tight lattice is at the best.As P/D=1.01,there is nearly no large scale coherent structure in the tight lattice.There is also nearly no momentum and energy exchange and the heat transfer is not very good.

Theoretical Study on Critical Heat Flux for Reactor Lower Head Using Subscale Boundary Layer Boiling Model

YANG Zhen, SU Guang-hui, TIAN Wen-xi, QIU Sui-zheng

2011, 32(6): 61-65.

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Based on the subscale boundary layer model,a preliminary boundary layer thickness analysis is performed,which is treated with the conservation equation,in order to calculate the CHF.Predictive results of CHF are obtained by selecting the largest entrainment coefficient.The angle,which implicates the change beginning of the two-phase boundary layer thickness,will increase with the increasing radius.The result of CHF increases observably with the angle,and the maximum value appears in 90 degrees.Comparing the predictive results with the experimental data,a better result of CHF prediction is obtained with the improved subscale boundary layer model.

Research on Out-of-Phase Oscillation in a Nuclear-Coupled Parallel Double-Channel Boiling System

ZHOU Ling-lan, ZHANG Hong, ZANG Xi-nian, LIU Yu

2011, 32(6): 66-70.

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In this paper,the RELAP5 thermal-hydraulic system code is coupled with the TDOT-T 3D neutron kinetic code by PVM（Parallel Virtual Machine）.A parallel double-channel boiling system is built by the coupled code and the instability boundary of out-of-phase oscillation in the system is obtained.The effects of axis power distribution and neutron feedback on the out-of-phase oscillation are analyzed in details.It is found that there are type-I and type-II density wave oscillation regions when the axial power peak is located at upstream of the heating section.At relatively lower values of fuel time constant,the neutron feedback always delays both types of density wave oscillations.

Study on Friction Resistance Characteristics of Narrow Rectangular Channel Single-Phase Isothermal Flow in Heaving Motion

LIU Xiao-zhong, HUANG Yan-ping, MA Jian, HUANG Jun

2011, 32(6): 71-75.

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Experimental investigation and physical analysis were carried out on friction resistance characteristics for single-phase isothermal flow in heaving motion.Results indicated that the effect of geometrical features for narrow rectangular channel only appeared in the laminar region.Influence factors of friction resistance characteristics of narrow rectangular channel in heaving motion are channel boundary conditions.The heaving motion have no effects on the isothermal flow if the boundary conditions are only related with the velocity,and the formula for friction resistance calculation obtained in the standstill works well in heaving motion.

Effect of Rolling Motion on Flow in Tight Lattice

YAN Bing-huo, GU Han-yang, YU Lei

2011, 32(6): 76-80.

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The flow oscillation and large scale coherent structure in tight lattice in rolling motion is investigated theoretically with URANS.The calculation results are consistent with the experimental data.The rolling motion may have effect on the flow oscillation and coherent structure.The oscillation period in rolling motion is about ten percent bigger than that in steady state.The coherent velocity in rolling motion is a little different from that in steady state.The minimum coherent streamwise velocity is at the channel center,while the maximum coherent streamwise velocity is at the transition region of the channel center and narrow gap.However,the effect of rolling motion on the flow and heat transfer characteristics in tight lattice is limited.

Numerical Simulation of Gas-Liquid Slug Flow inside Narrow Channels

ZHANG Wen-zhi, PAN Liang-ming, XU Jian-jun, HUANG Yan-ping

2011, 32(6): 81-85.

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Based on VOF model,the Taylor bubble and its surrounding characteristics of flow field are analyzed in a vertical rectangular narrow channel at different liquid flow rate.It shows that the relationship between the dimensionless bubble velocity and capillary number agrees well with those experimental results in cubic channels reported in literature The wall stress distribution around a gas slug has been investigated and the results show that the wall stress increases from the bubble nose to tail,but severe random motion would be occurred at the region behind the bubble tail.Meanwhile,as liquid flow rate increases,the Taylor bubble shape becomes much sharper and the liquid film thickness becomes thicker gradually,however,both the wall stress and the liquid axial velocity decrease and thus the portion of downward flow becomes shorter.

Numerical Investigation of Bubble Condensation of Subcooled Boiling in Narrow Rectangular Channels

PAN Liang-ming, TAN Zhi-wei, YAN Xiao, XU Jian-jun, HUANG Yan-ping

2011, 32(6): 86-90.

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The bubble condensation mass and energy transfer models for the subcooled boiling bubbles are developed,and the condensation progress for the bubbles is numerically simulated by VOF multiphase model.The simulation results agree well within ± 20% of the experiment results,which can reflect the real changing history of the parameters.Based on the simulation results,the effect of the initial bubble size,sub-cooling degree and system pressure on the bubble condensation behavior is analyzed.The analysis results show that the bubble lifetime in condensation is proportional to the bubble initial size;with the increasing of subcooling degree,the bubble lifetime will significantly reduce;vortex occurs at the region around the bubble,the higher the subcooling degree,the more intensive the vortex;vortex occurs also within the bubble in high subcooling degree boiling flow;and the bubble lifetime will be prolonged at higher system pressures in narrow rectangular channels.

Numerical Simulation of Fission Gas Swelling in Sintered Uranium Dioxide Fuel

XIAO Hong-xing, LONG Chong-sheng

2011, 32(6): 91-95.

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A model for the swelling behavior of fission gas in the range of low temperature of irradiated uranium dioxide fuel is established.In this paper,the finite difference method is adopted to compile a computational program and quantitatively calculated the fractions of fission gas as solid solution in UO₂,the density and average radius of intragranular bubbles and their contributions to the swelling of uranium dioxide fuel.in different burn-ups and temperatures of uranium dioxide fuel.The calculation shows that this model can be used to predict the fission gas swelling of uranium dioxide fuel versus burn-up in the range of low temperature.

Preliminary Study on Manufacture Process and Microstructure of Thin Rod Uranium-Zirconium Hydride Fuel Pellets

ZHANG Rui-qian, LIU Si-wei, JIANG Ming-zhong, LIU Chao-hong, PAN Qian-fu, LAN Guang-you, WANG Xiao-min

2011, 32(6): 96-100.

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Uranium-zirconium hydride fuel pellets were manufactured by the method of melting and casting U-Zr alloys and then hydrogenating the U-Zr alloys.The casting quality and yield were improved by changing the parameters of melting and casting process.U-Zr alloys were hydrogenated by using different parameters.The H/Zr atomic ratio of uranium-zirconium hydride fuel pellets was ranged from 1.41 to 1.71.The size of specimens was increased after hydrogenation process.The fuel pellet was composited by several phases,and uranium was present as metallic inclusions in a matrix of zirconium hydride.In addition,the concentration of hydrogen at fuel pellet brim was higher than that at fuel pellet center.

Experimental Study on Stress Corrosion Cracking of 316LN

KANG Huan-ju, YANG Shuang, SUN Hua

2011, 32(6): 101-104,114.

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5%,10% and 20% deformation are achieved to the 316LN matrix material respectively by rolling,then they are annealed at 1050℃ for 30 minutes.The specimens are made by the materials of different deformation in the two treatment conditions.After that,the SCC（stress corrosion cracking） experiment is carried out in boiling saturated magnesium chloride solution by the constant load tensile technology.Comparing with the SCC behaviors and crack growth rates of the specimens,the crack growth rate of 316LN is sensitive to the deformation.The bigger deformation changes,the poorer resistance to the SCC behavior and the faster crack growth rate.The treatment of rolling plus annealing leads better resistance to SCC behaviors than the treatment of rolling alone,indicating that the annealing can indeed improve the SCC resistance of 316LN.

Cause Analysis for Accelerated Aging of Condenser Rubber Expansion Joint in NPPs

ZHANG Sheng, ZHANG Tao, CHEN Shi-jun, CHEN Yu, JIANG Hong, HUANG Li-jun, LI Ji

2011, 32(6): 105-109.

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This paper analyzes the root cause for the accelerated aging of condenser rubber expansion joint according to the actual condition in Daya Bay Nuclear Power Plant and the experience feedback from overseas nuclear power plants.Life assessment is taken for rubber expansion joints and some specific management strategies and suggestions are recommended.The result shows that the aging mechanism of the rubber expansion joints include the embrittlement aging,fatigue aging,contacted media aging,stress fatigue and thermal aging caused by mechanics and environment.Embrittlement aging is the main aging mechanism.

Design and Analysis of Prevention and Mitigation Measures against Core Melting under High Pressure in RCS for CHASHMA NPP Unit 2

SHI Guo-bao

2011, 32(6): 110-114.

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A motor operated valve（MOV） is added on the Pressurizer for CHASHMA NPP Unit 2,to implement the bleed function in Feed-Bleed cooling mode,and depressurize rapidly the RCS during high pressure core melt in severe accident.This paper analyzes the accident consequence of Station Blackout co-incident with the loss of Diesel Driven Feedwater Pumps using the computer code of SCDAP/RELAP5/MOD 3.1,and the analysis results justify that the added MOV is able to depressurize the RCS effectively to mitigate the accident consequence in severe accident.

Feasibility Research of ⁹⁹Mo,³¹I and ⁸⁹Sr Production by Medical Isotope Production Reactor

DENG Qi-min, CHENG Zuo-yong, LI Mao-liang, ZHANG Jing-song, CHEN Yun-ming

2011, 32(6): 115-118,124.

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The recovery of ⁹⁹Mo and ¹³¹I was studied from simulation of Medical Isotope Production Reactor（MIPR） loop liquid delivery system,and the ¹³¹I recovery and ⁸⁹Sr purification from simulation of MIPR gaseous loop.The results indicated that the overall recovery yield of ⁹⁹Mo and ¹³¹I from simulation liquid delivery system were 56.4% and 50.2% respectively,while the contents of impurities meet Pharmacopoeia require.¹³¹I in gaseous loop can be recovered with absorbent,and the recovery yield is more than 90%.The ⁸⁹Sr recovered from by-pass gaseous loop can be purified by chemical separation,and the over all recovery yield of strontium is more than 70%,while the contents of impurities meet Pharmacopoeia re-quire.The results showed that MIPR can be used for ⁹⁹Mo,¹³¹I and ⁸⁹Sr production.

Heat Transfer Optimization of Once-Through Steam Generator

WEI Xin-yu, DAI Chun-hui, ZHAO Fu-yu

2011, 32(6): 119-124.

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The double-tube OTSG（Once-through steam generator） component is presented in this paper.Based on the analysis of the effects of the distribution ratio on heat transfer,the optimal distribution ratio is obtained by the constrained nonlinear optimization method.Subsequently,the optimal distribution ratio is achieved by a throttle setting in the entrance of the inner tube.

Shaking Table Test Study on Seismic Performance of Dehydrogenation Fan for Nuclear Power Plants

LIU Kai-yan, SHI Wei-xing, WANG Yang, CAO Jia-liang

2011, 32(6): 125-128.

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Seismic performance of the dehydrogenation fan for nuclear power plants was evaluated based on the shaking table test of earthquake simulation.Dynamic characteristics including the orthogonal tri-axial fundamental frequencies and equivalent damping ratios were measured by the white noise scanning method.Artificial seismic waves were generated corresponding to the floor acceleration response spectra for nuclear power plants.Furthermore,five OBE and one SSE shaking table tests for dehydrogenation fan were performed by using the artificial seismic waves as the seismic inputs along the orthogonal axis simultaneity.Operating function of dehydrogenation fan was monitored and observed during all seismic tests,and performance indexes of dehydrogenation fan were compared before and after seismic tests.The results show that the structural integrity and operating function of the dehydrogenation fan are perfect during all seismic tests;and the performance indexes of the dehydrogenation fan can remain consistent before and after seismic tests;the seismic performance of the dehydrogenation fan can satisfy relevant technical requirements.

Study of Utilization Alumina for ⁹⁹Mo and ¹³¹I Separation from UO₂（NO₃）₂ Solution

DENG Qi-min, CHENG Zuo-yong, LI Mao-liang

2011, 32(6): 129-132.

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Alumina（Al₂O₃） can be used for the extraction of MoO₄^2- and from UO₂（NO³）² soluTion.can be reduced to by using Sodium sulphite,then MoO₄^2- and IO₃^- can be separated with Al₂O₃ for the unadsorption of I^- on Al₂O₃.The total recovery yield of Mo and I is 78.3%±7.00% and 87.9%±5.48% respectively,after MoO₄^2- and IO₃^- in UO₂（NO₃）₂ solution were separated with two Al₂O₃ columns,and Mo in iodide products solution and I in molybdenic products solution meet the requirements.The results indicate that Al₂O₃ can be used for ⁹⁹Mo and ¹³¹I separation from the fuel of Medical Isotope Production Reactor.

2011 Vol. 32, No. 6