核动力工程

CFD Analysis of Thermal-Hydraulic Behavior of Supercritical Water in Square Sub-Channels

GU Han-yang, CHENG Xu, LU Dong-hua

2009, 30(2): 1-5.

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Investigations on the thermal-hydraulic behavior in the SCWR fuel assembly have obtained a significant attention in the international SCWR community.However,there is still a big deficiency in knowl-edge and prediction of the heat transfer in supercritical fluids.In this paper,CFD analysis is carried out to study the thermal-hydraulic of supercritical water flows in sub-channels of a typical SCWR fuel assembly using commercial CFD code CFX 5.6.Effects of various parameters,such as flow parameters,boundary con-ditions and pitch-to-diameter ratios on the mixing phenomenon between sub-channels and heat transfer,are investigated.The mixing phenomenon due to cross flow between wall sub-channels is much stronger than that between regular sub-channels.The turbulent mixing in tight lattice（P/d=1.1）is lower than that in wide lattice（P/d＞1.1）,whereas,the effect of pitch-to-diameter ratio on the turbulent mixing is slight at P/d＞1.2.It also shows unusual behavior in the vicinity of the pseudo-critical point and further investigation is needed.

Flow Behavior Analysis in Tight Lattice Rod Bundle Using CFD Method

YU Yi-qi, GU Han-yang, YANG Yan-hua, CHENG Xu, WANG Xiao-jun

2009, 30(2): 6-11,40.

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Tight lattice rod bundles have been applied to reactors due to lts high conversion ratio.How-ever,there still exists big deficiency in understanding of the coolant flow characteristics inside the sub-channels of tight lattices.This paper investigates the turbulence air flow behavior inside both square and triangular tight lattice.The validity of both eddy viscosity models and Reynolds stress models is assessed by comparing computational results with experimental data.The results show a reasonable prediction of the nu-merical analysis using the Reynolds stress model SSG,except for the flow behavior in the gap region between the rod and the wall.The SSG model is not sensitive to the mesh structure,in the case the size of the near wall meshes satisfies y⁺＜20,while the secondary moment closure ω model shows numerical oscillation with fine mesh sizes.

Experimental Study on Characteristics of Heat Transfer and Flow Resistance in Flat Tube

HE Shi-jing, SUN Zhong-ning, YAN Chang-qi, FAN Guang-ming

2009, 30(2): 12-15,54.

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Taking water as a medium,the experimental study on the heat transfer and flow resistance of three flat tubes with different geometric sizes is carried out.Experimental results show that the flat tube and circular tube with the same perimeter are with the same Reynolds number under the same water flow rate,however the heat transfer coefficient of the three flat tubes is higher than that of the circular tube and the larg-est heat transfer coefficient of the former can be 2.43 times of the latter.It is concluded that the flat tube is with a good heat transfer enhancement effect.Pressure drop of the latter is however higher than that of circu-lar tube.Finally,the heat transfer performance of horizontally and vertically laid flat tube in the casing pipe is studied and compared,and the experimental result indicates that the vertical one gains the advantage over the other.

Numerical Study of Forced Convection in a Vertical Channel Filled with Heat-Generating Porous Medium

YANG Jian, CENG Min, YAN Xiao, WANG Qiu-wang

2009, 30(2): 16-20,50.

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Steady laminar non-Darcian forced convection in a vertical channel filled with heat-generating porous medium is studied numerically by using the local thermal non-equilibrium model.The heat source generated by solid framework is uniform and kept constant;and the temperature of vertical walls is kept at constant temperature T₀.The flow inside porous medium is modelled by using Forchheimer-Brinkman ex-tended Darcy model.The effects of Reynolds number（0.5≤Re≤50）,effective fluid-to-solid thermal conduc-tivity ratio Γ（0.001≤Γ≤1.0）and Darcy number（10^-3≤Da≤10^-5）are analyzed in detail.It is found that,the effects of Re,Γ and Da are remarkable;at low values of Re and Γ,and at high value of Da,the effect of local thermal non-equilibrium is significant and the local thermal non-equilibrium model should be adopted for predicting the heat transfer characteristics exactly.

Study on Nonlinear Hydraulic Features of Water Circulation Systems at Supercritical Pressure

DOU Li-guo, KUANG Bo, GU Han-yang, LU Lu

2009, 30(2): 21-26,58.

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With establishment of a unified hydraulic model for both natural and forced circulation loops,and with considering the unique variation of thermo-physical properties at supercritical pressures,along with the nonlinear momentum transport and system coupling characteristics,this paper,by applying appropriate nonlinear numerical computation based on continuation concept,presents a systematic comparative study on the complex hydraulic features of both supercritical water systems.Special non-monotonic relationships of mass-flow rate and heating power of both natural and forced circulation,with their mechanisms and features,are revealed and comparatively investigated.Related thermal energy transmission issues of both systems are analyzed as well.Meanwhile,effects of such factors as inlet bulk temperature of heating section,local resis-tances and/or pump characteristics on system hydraulic and heat transmission features are delivered.Further-more,characteristics of forced circulation driven by both a real and ideal pump are compared.

Study on Calculation of Influence Function with Fracture Mechanics Analysis Method for Circumferential Through-Crack Pipe

ZHENG Bin, LU Yue-chuan, ZANG Feng-gang, SUN Ying-xue

2009, 30(2): 27-29,89.

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In order to widen the application of the engineering method of EPRI,with a series of analysis on the 3D elastic and elastic-plastic fracture mechanics finite element,the crack open displacements（COD）of cracked pipe were calculated and a key influence function h₂ in EPRI engineering method was studied against the COD results of FEM.A calculation method of h2 under the condition of tension and bending combined load was introduced in detail.In order to validate this method,the calculated h₂ results were compared with that of EPRI,and the calculated COD results based on the h₂ results were compared with that of PICEP.The compared results indicated that the calculated h₂ results as well as the COD results and the corresponding reference values were respectively accordant,and the calculation method in this paper was validated accordingly.

Safety Assessment of Metal Structure with Surface Plane Defects under Random Loads

LIU Qing-gang, SHEN Shi-ming

2009, 30(2): 30-32.

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Many metal structures with surface plane defects are always subject to random loads.In this paper,a simple safety assessment method for these structures is introduced.In this method,the distribution law of the random loads is simulated by the statistic parameter of the loads,and a certain method is used to deal with the real random loads.Monte-Carlo method is used to calculate the reliability of the structure.The relationship between the safety factor of the structure and the coefficient of variation（COV）of the random loads is studied.The results show that it is dangerous ignoring the random of the loads and the influence of the random of the loads can be measured by a safety factor.By using this safety factor,an equivalent invariableness load will be gained to be used in the safety assessment.

Study on Finite Element Analysis Technology for Weld Residual Stress

SUN Ying-xue, SUN Ping

2009, 30(2): 33-35.

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This paper describes the process of simulation weld flow with live-dead element and calculates the distribution of weld residual stress using the modal of the Ling’ao nuclear power station CRDM upper canopy seal weld,and the residual stress curve has been plotted.The comparison results show that the calculated result accords well with the data of WSI Company.It shows that the analysis technology for weld residual stress can be used to evaluate the repair of CRDM upper canopy.

Research on Vibration Properties of Auxiliary Bearing Cage Used in HTR-10 GT Project

TAN Qing-quan, YANG Guo-jun, SHI Zhen-gang, YU Su-yuan

2009, 30(2): 36-40.

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Auxiliary Bearings（ABs）is one of the most important parts in Active Magnetic Bearing（AMB）system,which was used in HTR-10 GT project.This paper uses finite element method to analyze the cen-trifugal stress and free vibration properties of the cage according to its work condition.And different geomet-ric parameters of the cage that has effects on its vibration performance are discussed.The results show that the highest centrifugal stress is in the middle of the cage side sill.The low oder vibration modes of the cage can be induced when the auxiliary bearings are working.Proper geometric parameters and ball pocket number can enhance the performance of the cage.

Analysis of Elastic-Plastic Dynamic Response of Reinforced Concrete Frame Structure

LI Zhong-cheng

2009, 30(2): 41-45,61.

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Based on a set of data from seismic response test on an R/C frame,a force-based R/C beam fibre model with non-linear material properties and bond-slip effects are presented firstly in this paper,and then the applications to the tested R/C frame are presented to illustrate the model characteristics and to show the accuracy of seismic analysis including consideration of non-linear factors.It can be concluded that the elastic-plastic analysis is a potential step toward the accurate modelling for the dynamic analyses of R/C structures.Especially for the seismic safety re-evaluation of the existing NPPs,the elastic-plastic methodology with consideration of different non-linearities should be involved.

Fracture Toughness and Failure Curve of 22NiMoCr3-7 Steel in Ductile-Brittle Transition Range

WANG Zhong-xian, WU Chun-du

2009, 30(2): 46-50.

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The numerical elastic-plastic analyses were processed by using FEA to three-point bend sam-ples in the ductile-brittle transition range.The samples are made of 22NiMoCr3-7 pressure vessel steel with single edge crack.Stress fields and constraint effects of the standard crack sample and the sallow crack sam-ple was assessed by using J-A₂ fracture theory.And the constraint parameters A₂ relating to the master curve reference temperatures T₀ were obtained.Based on J-A₂ approach and RKR fracture model,a formula to fore-cast fracture toughness was given.When it was used to forecast the fracture failure curves at different tem-peratures,the forecast results agree well with the experimental data.

Compatibility of Al-Si Eutectic Alloy and Zr-2 at Different Heat-Treatment Temperature

LIU Jin-yun, ZOU Cong-pei, CHA Wu-sheng, LAN Jun, YAN Shun, YAN Yan

2009, 30(2): 51-54.

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To investigate the compatibility of Al-Si eutectic alloy and Zr-2 at different heat-treatment temperature for different time,the couple of them was prepared by powder-metallurgy method.The micro-structure and element distribution have been measured with SEM,EDS,and XRD.It is shown that the heat-treatment temperature and the state of Al-Si alloy greatly influence the compatibility.At 650℃×40h,the dramatic diffusion layer has been formed due to the infiltration and diffusion of liquid Al-Si alloy.At 560℃×240h,the diffusion layer is very thin because there exists a solid state diffusion only.At 350℃×240h,due to a much smaller diffusion coefficient,almost no diffusion layer occurs,which means a good compati-bility between Al-Si eutectic alloy and Zr-2 at this temperature.

Analysis of Candidate Core Materials in SCWR Based on Boiler Materials of SCU

LIU Jin-hua, LI Zhang-xiang

2009, 30(2): 55-58.

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The core material of supercritical water cooled reactor（SCWR）is one of the sticking points for SCWR,while the operational conditions of supercritical unit（SCU）are greatly similar to SCWR.Me-chanical property,operating temperature and service environment for the materials of both the core of SCWR and the boiler of SCU were compared and discussed.Candidate materials of supercritical water cooled reactor were been put forward in this paper,such as T23,T91,T122,316,TP347H（FG）and Super304H.

Design Optimizations for Conventional Island for Ling’Ao Phase II Nuclear Power Plant

WU Zu-bing, CHEN Juan

2009, 30(2): 59-61.

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Ling’Ao Phase II Nuclear Power Plant is the first 1,000MW power project in China using domestic design methodology.Considering the operation and maintenance conditions,unequal column clearance is avoided as far as possible for main building design of Ling’ao Nuclear Power Station Phase II Conventional Island to satisfy the requirements on the module by civil construction.Since the external dimensions of turbine generator and condenser and the subsection length of deaerator of Ling’ao Nuclear Power Station Phase II are larger than those of Ling’ao Phase I,the first column clearance from South Side column B to column A is bigger than that of Ling’ao Phase I in view of the installation requirements of turbine generator,condenser and deaerator.The main building of Ling’ao Nuclear Power Station Phase II is arranged as three floors,i.e.,bottom floor,intermediate floor and operation floor.A continuous ring-type channel is formed in the intermediate floor for the convenience of equipment manipulation and maintenance by patrol inspection personnel and the intermediate floor thus becomes wider and brighter.

Conceptual Design for Experimental Main Loop with High Temperature Helium Gas

MA Li-hua, FENG Kai-ming, YE Xing-fu, CHEN Huan-xin

2009, 30(2): 62-64,74.

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Based on the design and running experiences on the helium experimental loops home and abroad,the preliminary conceptual design of the main helium loop,HTHEL,is completed according to the design requirements on TBM experimental section.The main design parameters,the system constitutes and main component characteristics for this loop are presented and the stress check is conducted for the design of main pipeline.

Flow Characteristics and Redesign of Highly Loaded Helium Compressors

WANG Song-tao, DU Xin, CHEN Ying, XU Li-min, MA Sheng-yuan

2009, 30(2): 65-69.

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Starting with the peculiarity of helium,the differences in choosing the design parameters be-tween helium compressors and air compressors are analyzed,and the characteristics in parameter selection to increase helium compressors loading are emphasized.Because the physical characteristics of helium are quite different from that of air,the flow in helium compressors is presented as low Mach number resulting in low stage pressure ratio,so generally the variation of passage size is less in helium compressors.In order to im-prove the stage loading and decrease the stage number,it is necessary for each stage to increase reactor.A numerical study is performed for a multistage Helium compressor to analyze the flow characteristics and the redesign is carried out in this paper.

Effect of Natural Circulation on RCS Depressurization Strategy in PWR NPP

ZHANG Kun, TONG Li-li, CAO Xue-wu

2009, 30(2): 70-74.

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The natural circulation model of Chinese Qinshan Nuclear Power Plant（NPP）Unit 2 is built using SCDAP/RELAP5 code.Selecting TMLB’ accident as the base sequence,this paper analyzes the natural circulation phenomena in high-pressure core melt severe accident.In order to study the effect of natural cir-culation on RCS depressurization strategy,the accident progressions of RCS depressurization with and with-out natural circulation are simulated,respectively.According to the results,the natural circulation can delay the initiation of RCS depressurization and the whole accident progression,but it does not evidently influence the results of RCS depressurization.

Bridge Balance Control of Fuel Handling Machine for Daya Bay Nuclear Power Plant

WU Feng-qi, LU Xiu-sheng

2009, 30(2): 75-77.

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In order to improve the outage efficiency of Daya Bay Nuclear Power Station,it is necessary to modify the motor-driven types of the fuel handling machine bridge,This paper focuses on the problems for the existing bridge crane for nuclear fule transportation and the characteristics and implementation of the new solution.After modification,the bridge crane was driven by two motors controlled by two separately motor drives,and a PLC was used to balance the operation of the two motors.This solution solved the synchronization problem under the high speed and long traveling distance for the bridge crane.

Migration and Control of Activated Corrosion Products in Primary Coolant Loop During Reactor Shutdown Oxygenation Operation

GAO Hui-bin, ZHANG Le-fu, FANG Jun

2009, 30(2): 78-81.

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The oxidation and purification of the primary coolant loop is of great importance in control-ling the dose rate during the outage.In this paper,the effects of pH value,H₂O₂ and H₂ concentration on the migration of activated corrosion products were discussed theoretically.A new method for the shutdown oxy-genation operation,characterized by low pH,low H₂ and introducing oxygen densely at suitable amount,was proposed based on the operation experience of Daya Bay nuclear power station.

Feasibility Verification for Operation Mode of APG Cation-Bed Changing to Ammonia-Type

WANG Lin, CUI Huai-ming

2009, 30(2): 82-85.

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For APG system in Ling’ao nuclear power station,ammonia-type operation mode is expected to replace the hydrogen-type mode.The analysis,evaluation and verification are performed for the feasibility of this replacement.The results of verification indicate that ammonia-type operation mode could extend the life of demineralizers and reduce the procurement cost of resin and the disposal cost of waste resin.Though the water treatment effectiveness of the demineralizers would be reduced to some extent,but still within the range required by the code.It is recommended to replace the current hydrogen-type cation resin operation mode and the corresponding measurement instrumentation.

Optimization of Leakage Calculation in RCP System of PWR

ZHAN Yong-jie, HE Zi-shuai, PAN Ze-fei

2009, 30(2): 86-89.

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RCP leak rate is a quite important parameter in PWR for its radioactivity,which is required to be calculated every day.However,the study on the RCP leak rate is inadequacy in China,and there is some shortness in its measurement and calculation.In this paper,based on the calculation of leak rate in QSII NPP,we try to summarize and optimize the calculation method for RCP leak rate in PWRs.

Pipe Leak Detection Based on Inverse Transient Analysis

LIU Zhi-yong, LIU Mei-qing, JIANG Jing, ZHAO Wen-sheng

2009, 30(2): 90-94.

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The pipe leak detection method based on ITA（Inverse Transients Analysis）was studied in this paper.The problem of pipe leak detection was converted to optimization problem.Taking the leak location and leak size as decision variables,the optimization model,in which the object function was to minimize the sum of square difference between calculation and measured value,was established.The GA（Genetic Arith-metic）,in which the 1-D approximation Vardy-Brown model was used to calculate fitness value,was applied to solve the optimization model.The feasibility of this method was validated by experiment.Moreover,through analyzing the main influence factors for the method,this paper pointed out that the detection result was impressible to the water hammer wave speed.

Prediction of Pipeline Corrosion Rate Based on Grey Markov Models

CHEN Yong-hong, ZHANG Da-fa, WANG Yue-min, PENG Gui-chu

2009, 30(2): 95-98.

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Based on the model that combined by grey model and markov model,the prediction of corro-sion rate of nuclear power pipeline was studied.Works were done to improve the grey model,and the optimi-zation unbiased grey model was obtained.This new model was used to predict the tendency of corrosion rate,and the markov model was used to predict the residual errors.In order to improve the prediction precision,rolling operation method was used in these prediction processes.The results indicate that the improvement to the grey model is effective and the prediction precision of the new model combined by the optimization unbi-ased grey model and markov model is better,and the use of rolling operation method may improve the predic-tion precision further.

Distributed Diagnosis Strategy and Its Application in Nuclear Power Plants

YAN Xiu-ping, PENG Min-jun, CHENG Shou-yu

2009, 30(2): 99-103.

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State monitoring and fault diagnosis are directly related to the safety,reliability and economy of nuclear power plants.Considering the fault diagnosis characteristics of nuclear power plants,this paper presented a method of distributed fault diagnosis and designed the Distributed Fault Diagnosis System of Re-actor Coolant System（RCSDFDS）.Experiments show that RCSDFDS is able to identify the single fault timely and accurately,and is with reasonable identification result for multiple faults.

Common Cause Failures Analysis of PWR Purification System Based on GO Methodology

HUANG Tao, CAI Qi, ZHAO Xin-wen, CHEN Ling, GUO Qiang

2009, 30(2): 104-107.

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GO methodology was applied to analyze the reliability of PWR purification system with common cause failures.The expression of purification system state probability was derived under the algo-rithm of GO methodology and the contribution to system unavailability caused by common cause failures was calculated in the way GO methodology dealing with it.The results show that the common cause failures greatly affect the reliability of PWR purification system.

Application of Ant Colony Optimization in NPP Classification Fault Location

XIE Chun-li, LIU Yong-kuo, XIA Hong

2009, 30(2): 108-112.

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Nuclear Power Plant is a highly complex structural system with high safety requirements.Fault location appears to be particularly important to enhance its safety.Ant Colony Optimization is a new type of optimization algorithm,which is used in the fault location and classification of nuclear power plants in this paper.Taking the main coolant system of the first loop as the study object,using VB6.0 programming technology,the NPP fault location system is designed,and is tested against the related data in the literature.Test results show that the ant colony optimization can be used in the accurate classification fault location in the nuclear power plants.

Aanalysis of Cementation Technology for Liquid Radioactive-Waste in PWR NPPs

CHEN Liang, CHEN Li, LI Jun-hua

2009, 30(2): 113-116,123.

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Cementation is one of the most pupular solidifacation technology for the low-and-intermediate levele liquid radioactive waste.It has been applied in all of domestic PWR NPPs.The process characteristics and operation of the cementations in the different NPPs are introduced,and the advantage and disavantage of the cementation are analyzed in this paper.A drum and a cask are compared as a package of the solidified waste,the drum can decrease over 50% final volume of the waste,furthermore the cost for manufacture and transportation for this drum is more cheaper than the cask,but an additional shielding may be necessary for the waste with higher level radioactivity that is packed in drum.More waste can be contained if an appropriate in-drum mixer is used while secondary waste will be unavoidable if the out-drum mixing is adopted.A carriage can make it easier to decontaminate on the surface of equipment and on the floor,furthermore the carriage is more economical than a roller conveyor in manufacture and maintainace.The cementation recipe for the waste should be optimized and additive material should be as less as possible to increase the containing rate of the waste.

Disposal and Close of Major Non-Conformity of Crack of Concrete Baseplate

ZHANG Zhi-hua, LIU Han-gang, QIAN Da-zhi, HUANG Hong-wen, DENG Yue, ZHOU Wei, YANG Guo-qing

2009, 30(2): 117-119,123.

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In terms of the quality assurance and control for nuclear engineering construction,this paper introduced the determination,origin analysis,remediation,disposal and close of the major non conformity of crack of concrete baseplate.

Delayed Supercritical Process with Temperature Feedback at Arbitary Initial Power

WANG Shao-ming, XU Guojun, ZHANG De

2009, 30(2): 120-123.

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By using the analytical method,the delayed supercritical process of nuclear reactor with tem-perature feedback while inserting small step reactivity（ρ₀＜β）is analyzed.The analytical expression of the relationship between reactivity and time is derived,and the variation curves of output power with time are obtained.The effects of the inserted step reactivity and initial power on the delayed supercritical process are analyzed and discussed.The results indicate that initial power of reactor can obviously influence the transient process.

Application of 3F Integrated Technology in New Product Development

LI Shu-qing, GAO Wei-sen, LIU Xiao-song

2009, 30(2): 124-128.

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3F integrated technology is a reliability analysis technology consisted of two modules,i.e.,FMECA and FTA,by methods based on a comprehensive analysis of potential failure prediction and improvement of function modules and the FRACAS prototype known fault closed-loop control function module.The research ideas that 3F integrated technology be applied to the whole process of new product development was described.The process model and the implementation of the operation flow of 3F integrated technology in the new product development were focused,and presentation of its case-specific process of implementation was given.Finally,for the 3F integrated technology and its application in new product development,pending development study were proposed.

2009 Vol. 30, No. 2