核动力工程

Analysis of Penetration Integrity under External Reactor Vessel Cooling

CAO Kemei, XU Yiquan, SHI Guobao, CAI Jianping

2011, 32(1): 1-5.

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When the molten core debris relocates to the lower plenum of the Reactor Pressurized Vessel（RPV） during a severe accident,penetrations may fail due to the thermal attack from the molten core debris,then the RPV loses its integrity,and molten core debris releases into the reactor cavity,resulting in the failure of In-Vessel Retention（IVR）.Based on the two kinds of penetration failure modes,i.e.penetration ejection and debris entering the penetration channel,the ablation of weld and friction force due to thermal expansion are calculated by VTA code,and flowing distance of debris along the penetration channel are analyzed with MBF model respectively.The results demonstrate that 300MW PWR plant RPV lower head will not lose its integrity due to penetration failure,and the molten core debris will not relocate to the reactor cavity through the failed penetrations if the External Reactor Vessel Cooling（ERVC） is performed.

Thermal Stratification and Fatigue Stress Analysis for Pressurizer Surge Line

YU Xiaofei, ZHANG Yixiong

2011, 32(1): 6-9,20.

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Thermal stratification of pressurizer surge line induced by the inside fluid results in the global bending moments,local thermal stresses,unexpected displacements and support loadings of the pipe system.In order to avoid a costly three-dimensional computation,a combined 1D/2D technique has been developed and implemented to analyze the thermal stratification and fatigue stress of pressurize surge line of QINSHAN Phase II Extension Nuclear Power Project in this paper,using the computer codes SYSTUS and ROCOCO.According to the mechanical analysis results of stratification,the maximum stress and cumulative usage factor are obtained.The results indicate that the stress and fatigue intensity considering thermal stratification satisfies RCC-M criterion.

Pseudo Excitation Random Seismic Response Analysis for Structures Equipped with Hysteretic Dampers

HUANG Qian, ZANG Fenggang, ZHANG Yixiong

2011, 32(1): 10-15.

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Hysteretic dampers have been widely used in the reactor coolant piping system as the energy absorbing components.In the paper,the random seismic response is evaluated through the pseudo-excitation principle incorporated with stochastic equivalent linearization method without by solving the Lyapunov differential equation for which the seismic excitation at support is limited to be shot noise process.It is supposed that the structures keep elastic and the hysteretic dampers are represented by the versatile Bouc-Wen model.With the aide of assistant matrices,the unidirectional and spatial excitation vectors of three components are derived and a pseudo-excitation closed-form expression for the system random response is established.Consequently,the stationary random seismic response of two shear type structure interconnected with hysteretic dampers is analyzed.The structural root mean square displacement responses for two methods agree well.Meanwhile,the parametric studies for initial yield force of the hysteretic dampers and the optimum way to install the hysteretic damper are discussed.

Quality Surveillance for PWR Power Plant Reactor Internals Manufacturing

WU Xiaokang

2011, 32(1): 16-20.

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The structure and the function of the reactor internals of the improved generation II PWR power plant is instructed briefly,the critical factors and difficulties in the manufacture process for reactor internals are analyzed,the quality control and surveillance of reactor internals manufacturing is discussed,especially the critical factors and difficulties of the quality control in the manufacture process for the main parts of reactor internals and in the reactor internals assembling process are represented in detail,the key points of the resident manufacture supervision is presented,and other key points of quality control in the manufacture process are also given,such as the documents control and personnel control.

Analytical Investigation on Steam Generator Tube Fretting Due to Foreign Object

CHEN Yinqiang, GUI Chun, WANG Xianyuan, LIU Hongyun

2011, 32(1): 21-24,33.

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The research investigated on tube fretting due to the outflow and vibration based on hypothesis that the tube can’t move to other places.Typical form and layout are considered as analytical objects.In addition,tube fretting due to foreign object is investigated using transient dynamics method according to Archard calculation model.The result shows that lower mass foreign object and foreign object with one end stationary have not remarkably affected on tube integrity under periodic fluctuating load.

Study on Issues of CPR1000 NPP Emergency Diesel Generator Test

LU Xiusheng, ZHONG Zhifei, YANG Yong

2011, 32(1): 25-28.

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During the design of CPR100P0 NPP,there is no special loads for emergency diesel generator tests,and there is no enough loads in emergency cabinets for the tests.In order to perform the test while do not occupy the outage critical time,a Mobile Test Load solution is provided in this paper.According to the existing CPR1000 design,dry mobile loads,breaker for interface with emergency diesel generator,and 2 junction boxes for interface with additional diesel generator are proposed.It is suggested that the interface and test loads for multi-units and multi-plants usage to be considered in NPP design phase.

Optimum Design of Steam Generator

WANG Meng, WANG Jianjun, SUN Zhongning, HE Shijing, YAN Changqi

2011, 32(1): 29-33.

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Taking the vertical U-tube natural circulation steam generator as an example,this paper puts forward the evaluation model of steam generator as well as the improved complex algorithm.The optimization design under the constraint conditions of various thermal performance and geometry construction is carried out.The results show that the optimal weight is 16.4% less than the original,and the volume is 16.3%.The optimization effect is very obvious.

Hydrogen Safety Analysis of Ling’ao Ⅱ NPP under LOFW+ATWS Accident

HUANG Xingguan, YANG Yanhua, FU Xiaoliang

2011, 32(1): 34-38,52.

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This paper applies the three dimensional CFD code GASFLOW to simulate the behavior of hydrogen and steam under hypothetical LOFW+ATWS accident.Analysis shows that the average temperature and pressure are dominated by the inventory of the steam released to the containment.The calculation results also show that during the hydrogen release time,the average recombine rate of the hydrogen mitigation system can reach 40g/s,but the flame acceleration criterion in the code assess that the flame acceleration may occur in quench tank compartment and pressurizer compartment during hydrogen release peak.

Analysis of Effect of Flashing Liquid Jet on Surrounding Instruments during LOCA

GU Peiwen, TAO Jun, CAO Xuewu, TONG Lili

2011, 32(1): 39-42.

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When the loss of coolant accident（LOCA） happens in the nuclear power plants,the coolant will be discharged to the low-pressure environment and evaporated immediately,causing damage to the surrounding instruments.The numerical software has been used to establish one-dimensional model for the prediction of possible damage in this severe accident,thus giving some advice for the nuclear power plant layout.The analytical result shows that the shock wave should be seen as a critical line,within which the instrument will be under high pressure,beyond which almost no mechanical damage will be caused.

Dependent-Dynamic Reliability Analysis of High-Order Redundancy System in Nuclear Reactors

GUO Qiang, ZHAO Xinwen, CAI Qi, CHEN Ling

2011, 32(1): 43-47.

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The redundancy pump group is a common subsystem in nuclear reactor systems,because of its overlap of warm standby,common cause failure（CCF） and other dependencies,and special effect of check valve group working simultaneously,the high-order one has various states and complex operation.The paper applies the dynamic reliability block diagram（DRBD） to build DRBD model of redundancy pump group,clearly expresses dependencies or dependent behaviors,and dependency parameters between components,and applies Monte Carlo simulation to simulate its operation and plots its fault probability change graphs.The result shows that the combining of DRBD and MC simulation is an effective method to analyze the depend-ent-dynamic reliability of high-order redundancy systems.

Effects of Digital Human-Machine Interface Characteristics on Human Error in Nuclear Power Plants

LI Pengcheng, ZHANG Li, DAI Licao, HUANG Weigang

2011, 32(1): 48-52.

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In order to identify the effects of digital human-machine interface characteristics on human error in nuclear power plants,the new characteristics of digital human-machine interface are identified by comparing with the traditional analog control systems in the aspects of the information display,user interface interaction and management,control systems,alarm systems and procedures system,and the negative effects of digital human-machine interface characteristics on human error are identified by field research and interviewing with operators such as increased cognitive load and workload,mode confusion,loss of situation awareness.As to the adverse effects related above,the corresponding prevention and control measures of human errors are provided to support the prevention and minimization of human errors and the optimization of human-machine interface design.

Optimization of Divergence Angle of Jet Pump Based on Numerical Simulation of Interior Flow Field

LONG Xinping, WANG Fengjing, YU Zhijun

2011, 32(1): 53-57,69.

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The divergence angle of a diffuser is one of the important structure parameters of the jet pumps,which has effect on the performance,interior flow field distribution and manufacture cost of the jet pump.In this paper,SIMPLE arithmetic and Realizable k-ε turbulence model is adopted to simulate the flow field and performance of jet pump of various divergence angles.The analysis on the centerline velocity,wall pressure distributions as well as the momentum correction coefficient and dynamic energy correction coefficient in the inlet and outlet of diffuser indicate that the divergence angle has less effect on the flow upstream the diffuser.It influences greatly the flow in the diffuser and downstream pipe.The effect of divergence angle on the performance and efficiency of jet pump is imposed by the resistance loss in the diffuser.Both the manufacture cost and pump efficiency should be considered together in the optimization of the divergence angle.Under a guideline of relatively changing 2.5% from the maximum efficiency point,the optimal divergence angle is proposed as 8°-11° considering the overall dimension and manufacture cost.

Investigation on Single Phase Water Reverse Flow in Inverted U-Tubes of Steam Generator under Condition of Natural Circulation

WANG Chuan, YU Lei

2011, 32(1): 58-62.

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Using the code RELAP5/MOD3.3 to model and calculate the natural circulation of single-phase flow for the PWR,this paper provides the distribution of forward flow and reverse flow in the inverted U-tubes of the steam generator（SG） under some typical operating conditions in the natural circulation case,and analyzes the cause,occurrence condition and judgment principle of reverse flow phenomenon.The calculation results show that the occurrence conditions for reverse flow phenomenon are that the steam generator outlet pressure is higher than the inlet pressure and gravitational pressure drop is lower than the total of frictional pressure drop and area change pressure drop.As to the nuclear power plant described in this paper,if the water level of steam generator keeps normal,the mass flux of the shorter U-tubes will drop more quickly and reverse flow will occur.The temperature distributes uniformly in U-tubes with reverse flow and it is almost identical with that of SG in secondary side.

Study on Turbulence Model of Supercritical Fluids Flow and Heat Transfer under Strong Buoyancy

ZHANG Hao, XIE Zhengrui, YANG Yanhua

2011, 32(1): 63-69.

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The buoyancy term of turbulence model is studied,and modification of the buoyancy model has been carried out.After that,several cases of supercritical flows with heat transfer are calculated and the results are compared with DNS and experiment data in the open literatures.The results show that the modified model can predict the buoyancy term correctly,and thus the calculated wall temperature agrees well with the experimental data and DNS data.In contrast,the wall temperature obtained by the traditional models is much higher than the experimental and DNS data.

Investigation on Self-Compensating Characteristics of Vertical Parallel Tubes with Low Mass Velocity

ZHU Xiaojing, BI Qincheng, YANG Dong, WANG Jianguo, CHEN Tingkuan, YU Shuiqing

2011, 32(1): 70-74.

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The physical model has been built up by using parallel six head internally ribbed pipes of Φ31.8 mm×6.0 mm to do the calculation for the vertical parallel tubes with self-compensating characteristics.According to the theoretical calculation result,the vertical parallel tubes with heat flux difference between pipes have obvious self-compensating characteristics.Meanwhile,the mass velocity of water in the pipe with lower heat flux goes down first and then goes up with the increasing of heat absorption.When the steam quality reaches high level,the mass velocity in lower heat flux tube meets or exceeds the average value and the self-compensating characteristics of the system disappears.The experimental research has been carried out based on the calculation result.The experimental results show that the quality and the heat flux difference between pipes have great effect on the self compensation characteristics of the system.The mass velocity in the tube with less heat flux decreased first with the rising quality and then increased.Self-compensating characteristics of vertical parallel tubes disappears when quality gets high.The experimental results also show that when the quality is low,the increasing of the uneven heating ratio strengthens the self-compensating characteristics of the system,in contrast,while the quality is high,the increasing of the uneven heating ratio weakens it.

Experimental Investigation on Heat Transfer Characteristics of Water in Vertical Upward Tube under Supercritical Pressure

PAN Jie, YANG Dong, DONG Zichun, ZHU Tan, BI Qincheng

2011, 32(1): 75-80.

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Within the range of pressure from 22.5 to 30 MPa,mass flux from 1009 to 1626 kg/（m²·s）,and inner wall heat flux from 216 to 822 kW/m²,an in-depth experiment was conducted under supercritical pressure to investigate the heat transfer characteristics of water in vertical upward smooth tube.The heat transfer characteristics of water under supercritical pressure were obtained in the experiment.The effects of pressure,inner wall heat flux and mass flux on the heat transfer coefficient and inner wall temperature were analyzed,the heat transfer mechanism was discussed,and the corresponding empirical correlations were also presented.The experimental results show that when the bulk fluid temperature is near the pseudo-critical temperature,the tube wall temperature increases slowly with the fluid enthalpy,the heat transfer coefficient gets larger abruptly and the heat transfer enhancement phenomenon occurs in the smooth tube.Otherwise,the tube wall temperature increases obviously with the increasing fluid enthalpy and the heat transfer coefficient is low.With the increase of pressure and inner wall heat flux,and with the decrease of mass flux,the inner wall temperature increases,the heat transfer coefficient decreases and the heat transfer enhancement is weakened.With the increase of inner wall heat flux,the maximum of heat transfer coefficient appears ahead.

Study on Heat Transfer and Hydraulic Model of Spiral-Fin Fuel Rods Based on Equivalent Annulus Method

ZHANG Dan, LIU Changwen, LU Jianchao

2011, 32(1): 81-84,94.

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Tight lattice fuel assembly usually adopts spiral-fin fuel elements.Compared with the traditional PWR fuel rods,the closely packed and spiral fin spacers make the heat transfer and hydraulic phenomena in sub-channels very complicated,and there was no suitable model and correlation to study it.This paper studied the effect of spiral spacers on the channel geometry in the equivalent annulus and physical performance based on the Rehme equivalent annulus methods,and the heat transfer of the spiral fin fuel rodsand hydraulic model were obtained.The new model was verified with the traditional one,and the verification showed that two new models agreed well,which could provide certain theoretical explanation to the effect of the spiral spacer on the thermal hydraulics.

Visual Experimental Investigations on Single-Phase Flow in Narrow Rectangular Channel with Longitudinal Vortex

MA Jian, HUANG Yanping, HUANG Jun

2011, 32(1): 85-88.

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Four pairs of rectangular blocks as longitudinal vortex generators（LVG） were mounted periodically in a narrow rectangular channel.To investigate the fluid flow structure in the channel,PDPA was employed to visually measure the single-phase velocity distribution.The velocity distribution of laminar and turbulent regime indicates that the longitudinal vortex will produce in the shape of secondary flow when the flow pass LVG,the development of flow boundary layer is restrained or broken,and the flow convective motion will be strengthened in the channel,so the heat transfer in the channel can be enhanced.This experiment reveals the qualitative physical mechanism of heat transfer enhancement in the narrow rectangular channel with longitudinal vortex.

Experimental Investigations on Single-Phase Heat Transfer Enhancement in a Narrow Rectangular Channel with Longitudinal Vortex

MA Jian, HUANG Yanping, HUANG Jun

2011, 32(1): 89-94.

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Four pairs of rectangular block as longitudinal vortex generators（LVG） were mounted periodically in a narrow rectangular channel to investigate the fluid flow and convective heat transfer respectively in the narrow rectangular channel with LVG and without LVG.The experiments were performed with the channels oriented uprightly and uniform heat fluxes applied at the one side of the heating plate and single-phase water was used as test fluid.In these experimental investigations,both laminar regime and turbulent regime were under the thermo-hydraulic developing conditions,laminar-to-turbulent transition occurred in advance with the help of LV when Reynolds numbers vary between 310 and 4220.In laminar regime,LV causes heat transfer enhancement of about 100.9% and flow resistance increase of only 11.4%. And in turbulent regime,LV causes heat transfer enhancement of above 87.1% and flow resistance increase of 100.3%.As a result,LV can obviously enhance the heat transfer of single-phase water,and increase the flow resistance mildly.

Analysis and Discussion of Flow Boundary Layer in Fully Turbulent of Narrow Rectangular Channel

XU Jianjun, CHEN Bingde, WANG Xiaojun

2011, 32(1): 95-98,103.

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This paper presents the flow and heat transfer in a narrow channel from the macrocosmic view,and the discussion of the flow boundary layer of the narrow rectangular channel by analysis of the results obtained by CFD code.The results show that some classical formulas in single phase are applied for narrow rectangular channels,and the current experimental results support the view that the flow and heat transfer of a narrow rectangular channel accords with that of an ordinary sized channel in fully turbulent.Secondly,the results obtained by CFD code with different turbulent models are compared with the classical formulas and experimental data,which shows that results obtained by CFD code is credible.Finally,according to microcosmic results obtained by CFD code and the velocities near the wall obtained by the classical formulas,the characteristics on flow boundary layer of the narrow rectangular channel in fully turbulent is discussed in detail.

Experimental Research on Single Phase Convection Heat Transfer in Micro-Fin Tube

FAN Guangming, SUN Zhongning, ZHU Sheng

2011, 32(1): 99-103.

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An experimental investigation of heat transfer and flow resistance characteristics of single phase water in three micro-fin tubes with different fin height was conducted.At the same time,the efficiency of micro-fin tubes within the experimental scope was evaluated and the optimal working region was determined.Based on the experimental data in the optimal working region,correlations for predicting the heat transfer and flow resistance were also given by multiple regression method.The result indicates that the micro-fin tubes can greatly enhance the single-phase heat transfer in turbulent flow,and the increase of heat transfer coefficient is higher than the increase of flow resistance.The accuracy of the correlation is very high,of which the deviation from the experimental value is very small.

Flow Pattern Characteristics of Pool Boiling in Inclined Confined Spaces

WEN Qinglong, CHEN Jun, ZHAO Hua

2011, 32(1): 104-107,121.

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In this paper,visualization of bubble behavior and two-phase flow in inclined confined spaces are performed for near-saturated demineralized water at atmospheric pressure with gap sizes of 3mm to 8mm,and inclination angles of 0° to 30°.Based on the results,three boiling regimes are observed:isolated deformed bubbles,coalesced deformed bubbles and partial dry-out.A flow pattern map for confined pool boiling,based on the Bond number and a dimensionless number of heat flux,has been developed in order to determine the regimes.Objective criteria are proposed for the transitions between various regimes.It is shown that the transition criteria between isolated deformed bubbles and coalesced deformed bubbles is Q=0.16 and Q=0.55 between coalesced deformed bubbles and partial dry-out.It has to be pointed out that the gap structures and downward facing heating surfaces may be responsible for the special flow patterns

LES Research on Flowing Characteristics of Turbulent Flow in Rectangular Tubes in Rolling Motion

YAN Binghuo, GU Hanyang, YANG Yanhua, YU Lei

2011, 32(1): 108-111,116.

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The turbulent flow in rectangular tubes in rolling motion is investigated theoretically with FLUENT code and large eddy simulation.The effects of rolling motion and tube size on the flowing characteristics of turbulent flow are analyzed.The results show that if the rectangular tube is narrow,the effect of rolling motion on the turbulent flow can be depressed by the tube wall.If the rolling amplitude is small,the effect of rolling motion on the turbulent flow is very limited.With the decrease of length-width ratio of the tube,the turbulent frictional resistance coefficient decreases.The frictional resistance coefficient is in a wave or slope shape.If the rolling amplitude is big,the counter flow occurs first at the π/2 phase.With the decrease of rolling period,the frictional resistance coefficient on the wall decreases first,and increases later.

Research on Single-Phase Forced Circulation in Rectangular Channel Flow haracteristics under Rolling Conditions

XING Dianchuan, YAN Changqi, LIU Yang, GAO Puzhen

2011, 32(1): 112-116.

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Studies on the single-phase flow characteristics in rolling rectangular channel were carried out using the deionized water as the working fluid under normal temperature and pressure.The single-phase water friction coefficient under rolling conditions is obtained,according to the pressure drop measured by experiments.Experimental results show that the volume flow of the closed loop cyclical fluctuations under rolling conditions.The amplitude of fluctuation increased with increasing rolling amplitude and frequency,and the average volume flow decreased due to the rolling motion.The average friction coefficient in rolling is larger than the one in the steady-state,which depends on the rolling amplitude,rolling cycle and the average Reynolds numbers.Empirical correlation for the average friction coefficient under rolling conditions is obtained by fitting a large number of experiment data.

Study on Neutron Amplification Factor of Fast-Zone in VENUS 1^# on Unidirectional Coupling Mode

XIE Jinsen, YU Tao, QIAN Jindong

2011, 32(1): 117-121.

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VENUS 1^# was the first fast-thermal coupled accelerator driven sub-critical experimental facility of the world built by China Atomic Energy Institute-CIAE.In this paper,the leakage and net neutron yield of fast zone and leakage neutron spectrum driven by ²⁵²Cf,Am-Be and D-T neutron sources with different loading layers was calculated based on VENUS 1^# unidirectional coupling mode.The results show that,from the view of energy production and transmutation,there exists optimized fuel loadings of fast-zone,which will provide theoretical basis for designing "fast-thermal" unidirectional coupling systems.

Optimization and Selection of Long Fuel Cycle Reloading Pattern for Qinshan Project Ⅱ

PAN Zefei, YE Guodong, XIANG Junjun, HE Zishuai, DAI Qianjin, ZHAN Yongjie

2011, 32(1): 122-126.

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Reloading pattern is the basic and most important item during the process of the fuel management strategy modification.It has great effects on the safety and economic performance of the nuclear power plants.Unit 1 and 2 in Qinshan project Ⅱ will modify the fuel management strategy once more after the modification of AFA-2G&AFA-3G mixing core with raising the enrichment.This paper introduces the whole process to optimize and select the reloading pattern for Qinshan Project Ⅱ based on the requirements of long fuel cycle management strategy.

2011 Vol. 32, No. 1