核动力工程

Seismic Analysis of Structure under Influence of Fluid

Tan Tiancai, Gao Lixia, Ma Jianzhong

2016, 37(S2): 1-3. doi: 10.13832/j.jnpe.2016.S2.0001

Abstract(23) PDF(0)

Abstract:
The complete finite element model of reactor inernals of a certain type test reactor including grid plate assembly and core component is established. Modal combination method of CQC is adopted for the spectrum analysis of the reactor internals. Effect of added mass in still water on the transverse vibration characteristics of the reactor core is considered, but the effect of the added mass of water on the axial direction is ignored. Then two finite element models are established: one is the approximate model of the reactor internal in the water, which is used for spectrum analysis of structure under transverse earthquake load. Another is the model of the reactor internal in the air, which is used for the spectrum analysis under axial direction earthquake load and static analysis under gravity. The results show that the reactor internals are in compliance with the requirements of ASME codes.

Analysis of Weld Overlay Residual Stress for Dissimilar Metal Welds in Qinshan Nuclear Power Plant

Zhang Shiwei, Chen Xuede, Zhang Yong, Sun Lei, Li Xihua

2016, 37(S2): 4-6. doi: 10.13832/j.jnpe.2016.S2.0004

Abstract(19) PDF(1)

Abstract:
Alloy 82/182 were used extensively in PWR primary coolant system as the DMW weld structure for the pipe nozzle and pipelines. The dissimilar metal welds（DMW） easily appears cracking due to the stress corrosion and fatigue after long operation. Based on the service data from foreign nuclear powers, the primary water stress corrosion（PWSCC） is the major factor for cracking, which is sensitive to the stress of pipe inside surface. The structural weld overlay repair is an appropriate way to repair the operating nuclear reactor piping according to the international experiences. Based on the nozzle of Qingshan nuclear power phase I, the axis symmetric FE model was set up to simulate the welding procedures and obtain the thermal field and residual stress field at the area of DMW weld by ANSYS finite element analysis software. The residual stress analysis indicated that PWSCC will be prevented by the resulted inside surface stresses after weld overlay.

Decoupling Solution and Verification of Free Vibration Equation of Curved Beam

Li Xingzhao, Li Pengzhou, Sun Lei

2016, 37(S2): 7-10. doi: 10.13832/j.jnpe.2016.S2.0007

Abstract(25) PDF(0)

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Based on Euler-Bernoulli beam model, this paper establishes the differential equation of arc-curved beam in the free vibration state, and the decoupling solution is theoretically derived, and verified with FEM method. The results show that the modal frequency results of the theoretic method differ from the ones of FEM method within 2% in the low-frequency area.

Crack Growth Analysis of Ω Seal Overlay Weld Repair for CRDM

Luo Jiacheng, Zhang Yong, Li Pengzhou, Luo Juan, Sun Lei

2016, 37(S2): 11-13. doi: 10.13832/j.jnpe.2016.S2.0011

Abstract(24) PDF(0)

Abstract:
The Control rod drive mechanism（CRDM） is a key device in the nuclear reactor, and the pressure shell of CRDM is installed on the canopy of the reactor pressure vessel by the Ω seal weld. The primary water stress corrosion is the major factor for the cracking of Ω seal weld, resulting in the leakage of coolant. The structure integrity of the Ω seal can be insured by the overlay weld technology. Based on the fracture mechanics analysis method, this paper investigates the crack growth of the overlay weld structure on the Ω seal of control rod drive mechanism, induced by the fatigue and the stress corrosion. The calculation method and results can be a reference for the overlay weld structure design and assessment of the Ω seal in CRDM.

Three Key Mechanical Problems of Flow Induced Vibration of Tube Bundles in Two-Phase Flow

Jiang Tianze, Li Pengzhou, Ma Jianzhong, Gao Lixia, Lai Jiang

2016, 37(S2): 14-19. doi: 10.13832/j.jnpe.2016.S2.0014

Abstract(28) PDF(0)

Abstract:
The tube bundle of heat exchange apparatus may generate flow induced vibration（FIV）under the fluid force. Excessive FIV can cause damage to the heat exchanger components, especially the U-bend section of the nuclear steam generator in two-phase flow. Because of the complexity of two-phase flow and complex structure of tube bundles and strong coupling effect between them, there exist three key mechanical problems of FIV of Tube Bundles in two-phase flow: modeling of two-phase flow, identification of kinetic parameters of FIV and study of FIV mechanism in two-phase flow. In the paper the view of the three above points are reviewed and discussed, and problems to be solved are proposed.

Vibration Characteristics of a Core Barrel with Conventional and Unconventional Core Support Barrel

Lai Jiang, He Chao, Xi Zhide, Sun Lei, Li Pengzhou

2016, 37(S2): 20-23. doi: 10.13832/j.jnpe.2016.S2.0020

Abstract(20) PDF(0)

Abstract:
The flow-induced vibration（FIV） of the core barrel is very common, and the characteristics of the FIV is important to the security of the nuclear reactor. By monitoring the vibration characteristics of the core barrel, the natural frequencies of the core barrel would decrease, as the nuclear reactor is running, especially for the fundamental natural frequency of the core barrel. It is difficult to calculate this problem with the conventional method. In order to solve this problem, a new method to simulate loose-joined flange between the top of the core support barrel（CSB） and the head of the vessel was presented in this paper. The dynamical finite element model of the structure of the bore barrel was obtained and the fundamental frequencies of the core barrel were calculated, including 8 situations, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% loose-joined flange between the top of CSB and the head of the vessel. The comparison between the calculated results and the experimental ones show that the method developed in this paper is reasonable and feasible.

Study on Flow-Induced Vibration for Pipe Conveying Fluid Based on Two Way Coupling Method with CFD and FEM

Liu Guixiang, Zhang Kun, Lin Song

2016, 37(S2): 24-27. doi: 10.13832/j.jnpe.2016.S2.0024

Abstract(25) PDF(0)

Abstract:
The two way coupling numerical model for a typical pipe conveying fluid is established based on two way coupling method with CFD and FEM, and the dynamic characteristics of flow-induced vibration are obtained. The effects of flow velocity, stiffness and location of pipe supports on its flow-induced vibration characteristics are studied. It can conclude that the low frequency vibration can be excited by hydrodynamic loading, and the low frequency line spectrum is significant. The flow-induced vibration of pipe is closely related to the flow velocity inside, the stiffness and location of pipe supports. There is a positive correlation between the flow velocity of fluid inside and the total flow-induced vibration level of the pipe. The effect of stiffness and location of pipe supports on its spectrum distribution characteristics for flow-induced vibration is significant, and the resonance frequency of equipment and valve can be avoided by optimizing the parameters of pipe supports.

Analysis of Flow-Induced Vibration of Nuclear Reactor Internals

Lai Jiang, Yang Jie, Xi Zhide, Sun Lei, Li Pengzhou

2016, 37(S2): 28-31. doi: 10.13832/j.jnpe.2016.S2.0028

Abstract(22) PDF(0)

Abstract:
The flow-induced vibration characteristic of a new nuclear reactor was analyzed in this paper by performing dynamic test and numerical calculation. A 1/2 scaled-down model of a new designed nuclear reactor was manufactured for performing the dynamic test with the hydrodynamics simulation system at the 100% operation condition. And the dynamical responses of core barrel and secondary core support structure were measured in the test. Based on the results of the dynamic test, a three-dimensional finite element model of the reactor internals for the numerical analysis was constructed to obtain the max strains and stresses of core barrel and secondary core support structure at the 100% operation condition.

Analysis Method for Flow-Induced Random Load of Reactors

Lin Song, Liu Tianyan, Zhang Kun, Xie Xiaoyi

2016, 37(S2): 32-36. doi: 10.13832/j.jnpe.2016.S2.0032

Abstract(25) PDF(0)

Abstract:
Due to the complexity of flow induced vibration in reactors, previous studies mainly focused on the experimental research. Based on the analysis of the random responses of core structures excited by fluctuating pressures, the fluctuating pressures is obtained experimently by scale model. The theoretic method is developed to analyze the random load on the core structures. The load spectrum obtained by this method can be used for the analysis of the response of core structures.

Study on Flow Induced Vibration in Reactor Internals of HPR1000

Yang Jie, Xi Zhide, Yu Danping, Ma Jianzhong, He Chao, Tan Tiancai

2016, 37(S2): 37-39. doi: 10.13832/j.jnpe.2016.S2.0037

Abstract(31) PDF(1)

Abstract:
The flow induced vibration is studied in this paper by the combined methods of experiment and simulation. Based on the similarity criterion for the flow induced vibration, a 1:5 test model is designed. According to the RG1.20, the experiment study and analysis and calculation are conducted by finite element method. The challenges in the layout of sensor are solved in this test, and full test data are obtained. Based on the test data, the response of the key structures is obtained. Finally the comprehensive assessment for nuclear reactor internals fatigue strength is implemented. These methods can be of important reference value for other reactor internals FIV studies.

Research of Flow Induced Vibration Test for CAP1400 Reactor Internals

Xu Jing, Liu Linlin, Yu Danping, Ma Jianzhong, Li Xihua

2016, 37(S2): 40-43. doi: 10.13832/j.jnpe.2016.S2.0040

Abstract(33) PDF(0)

Abstract:
Referring to the CAP1400 reactor, the test model was constructed with a linear reduced scale of 1/6. FIV test of CAP1400 reactor internals have been done under all kinds of conditions, and complete data is obtained. According to FIV test results, it can be concluded that the design of CAP1400 reactor internals is reasonable and safe on the aspect of flow induced vibration. And it also provides evidences for nuclear safety reviews.

Test Studies of Flow Induced Vibration for Fuel Assembly

Zhang Xiaoling, Li Tianyong, Ma Jianzhong, Liu Litao, Li Pengzhou

2016, 37(S2): 44-46. doi: 10.13832/j.jnpe.2016.S2.0044

Abstract(18) PDF(0)

Abstract:
Test method is used to research fuel’s natural characteristics and flow induced vibration responses. It obtained the natural frequencies, and responses rule that is flow induced vibration responses increased with flow increases. Then it achieved waterfall for amplitude, frequency and time（flow） on transient state; and movement trace of grid. The full and reliable test data will be an input for the design, safety analysis and fretting test; and support the safety evaluation.

Review of Experimental Research of Flow-Iinduced Vibration of Reactor Internals

Yu DanPing, Ma Jianzhong, Xi Zhide, Yang Jie

2016, 37(S2): 47-51. doi: 10.13832/j.jnpe.2016.S2.0047

Abstract(38) PDF(0)

Abstract:
This paper reviews the experimental research of flow-induced vibration（FIV） of several reactor structures completed in recent years, such as FIV test of reactor internals of Qinshan Phase Ⅱ, 1:5 model FIV test of reactor internals of ACP1000, and comprehensive vibration assessment plan for HPR1000 reactor internals. Comprehensive vibration assessment of these structures were carried out according to U.S. Nuclear Regulatory Commission R.G..1.20. Analysis methods of FIV are also described. The experiences of FIV research and assessment were accumulated. Finally, how to effectively assess FIV of reactor structures is discussed. Possible future work is prospected.

Analysis of Dynamic Characteristics Test for Reactor Internals

Xu Jing, Yu Danping, Ma Jianzhong, Li Xihua

2016, 37(S2): 52-55. doi: 10.13832/j.jnpe.2016.S2.0052

Abstract(17) PDF(0)

Abstract:
In this paper, testing principle, testing method, testing measurement system, and testing result have been introduced. According to the result, it can be concluded that the result of the test is reasonable and believable.

Study on Dynamic Characteristics of Extension-Type Fuel Assembly

Zhang Xiaoling, Zhao Hui, Yu Danping, Liu Litao, Sun Lei, Ma Jianzhong

2016, 37(S2): 56-57. doi: 10.13832/j.jnpe.2016.S2.0056

Abstract(24) PDF(0)

Abstract:
Numerical analysis combined with test which adopting impacting method is used to achieve the dynamic characteristics of fuel assembly under different boundaries. Firstly, finite-element analysis method is used to predict the natural frequency of fuel assembly, and the results supply a reference for test parameter setting and identification. Then the test adopts the impacting method, single-point excitation and multiple-point vibration pickup, to obtain the natural frequencies and modes. The results from the test and the numeric analysis are uniform.

Exploration of Seismic Qualification Test Method for Nuclear Safety Class Valves

Li Qi, Li Pengzhou, Du Jianyong, Li Tianyong, Sun Lei, Li Pengfei

2016, 37(S2): 58-61. doi: 10.13832/j.jnpe.2016.S2.0058

Abstract(20) PDF(0)

Abstract:
Seismic qualification test must be conducted for the valves which are used in the nuclear power stations. When the valves are qualified for the seismic qualification in the first time, the test method is available. Among the existence criterions of the seismic qualification for valves, the seismic qualification test includes single-frequency sine wave test, consecutive sine sweep wave test, multi-frequency wave method, and so on. In this paper, a type of valve is exampled by three methods of seismic qualification tests. Then, the results of the three methods are compared, which provide a wide ways and reference to improve seismic qualification for valves.

Construction of Database on Nuclear Equipment Qualification Analysis and Test Data

Liu Linlin, Li Pengzhou, Li Qi, Li Pengfei

2016, 37(S2): 62-64. doi: 10.13832/j.jnpe.2016.S2.0062

Abstract(29) PDF(0)

Abstract:
Employing Oracle database program, following the basic table design based on the third paradigm, a database on nuclear equipment qualification analysis and test data was constructed. The establishment of the database using the index, partition, SQL optimization methods is able to efficiently integrate the various types of data generated in computational analysis and tests. It shows good scalability, extensibility, fast response and convenient maintenance.

Research on Vibration Issue due to Pipe Orifice Cavitation

He Chao, Lai Jiang, Yan Junming, Xi Zhide, Yuan Shaobo, Sun Lei

2016, 37(S2): 65-69. doi: 10.13832/j.jnpe.2016.S2.0065

Abstract(24) PDF(0)

Abstract:
The vibration issue due to pipe orifice cavitation of NPP containment spray system（EAS） is analyzed combining the field vibration test and numerical simulation analysis method. The study finds that pipe orifice plate choking leads to the emergence of cavitation downstream of the orifice plate, which resulting in the pipeline vibration. The optimization design of the pressure drop, number of stages, aperture and structure of the orifice is conducted by numerical calculation. The scheme of reducing the cavitation using the three-stage orifice is presented and the integrity evaluation of the scheme is carried out. Through the re-appraisal of the modified pipeline, it is shown that the engineering design scheme based on the optimal design and analysis method can solve the problem of strong vibration of piping induced by cavitation, and greatly reduce the vibration and noise of pipeline, and the pipeline system can be safely operated in long term.

Study on Seismic Test of CAP1400 Control Rod Drive Line

Li Qi, Li Pengzhou, Li Xihua, Sun Lei, Du Jianyong, Li Tianyong, Xie Yongcheng

2016, 37(S2): 70-72. doi: 10.13832/j.jnpe.2016.S2.0070

Abstract(24) PDF(0)

Abstract:
The seismic test of CAP1400 control rod drive line was conducted on the multiple point excitation test device. The horizontal direction and vertical direction of the CRDL were excited with multi-frequency earthquake time history at the same time. The strain values and acceleration of test piece under LLSE and SSE level were measured. The seismic test shows that CAP1400 CRDL can keep the structural integrity and operability under the seismic condition.

Status for Fretting-Wear Study of Nuclear Structural Components

Gao Lixia, Li Pengzhou, Lai Jiang, Ma Jianzhong, Xi Zhide

2016, 37(S2): 73-76. doi: 10.13832/j.jnpe.2016.S2.0073

Abstract(25) PDF(0)

Abstract:
Flow-induced vibration of steam generator tubes or fuel rods results in fretting-wear damage due to impacting and rubbing of the tubes against their supports or fuel rods against their grids. Tubes and fuel rods are working at high temperature and pressure. The damages should be bad for the safety of nuclear reactors. Temperature and water chemistry are the key parameters for fretting-wear. This paper introduces the status for the studies of fretting wear in the world.

Vibration Evaluation of Small Bore Pipe in NPPs Based on Strain and Acceleration

Shen Shuangquan, Xu Yugen, Zhang Shiwei, Li Xin

2016, 37(S2): 77-79. doi: 10.13832/j.jnpe.2016.S2.0077

Abstract(29) PDF(0)

Abstract:
Small bore pipes, existing in a form of large quantities of instrument pipes, sampling pipes and vent pipes, often suffer mechanical vibration fatigue fracture. Vibration fatigue life is evaluated according to measured vibration stresses for GRE023 pipes in Unit 2 of Yangjiang NPP. Measured acceleration time history were double integrated into the displacement time history for vibration fatigue life analysis by finite element method, and key parameters for transient dynamic analysis were also determined, which lays an empirical foundation for vibration reduction of analogical structure. The analytical method can provide a reference for small bore pipe vibration reduction in NPPs.

Vibration Attenuation Design of Plate and Shell Support Structure

Lu Jun, Zhang Kun, Liao Kuai, Sun Lei

2016, 37(S2): 80-84. doi: 10.13832/j.jnpe.2016.S2.0080

Abstract(20) PDF(1)

Abstract:
The blocking mass, frame style structure and elasticity separated devices are imported to the plate and shell supports. Schematic designs of vibration attenuation are conducted and simulation model of both modified and primary support structures are constructed, then the vibration transmission characteristics from the plate and shell support structures to the hull is analyzed and the attenuation of every measure also calculated by means of numerical simulation when vibration excitation of bump is bear on upon the model. Numerical results show that the attenuation of blocking mass, frame style structure and elasticity separated devices can achieve 3 d B, 10 d B and 40 d B, respectively. Considering reasonable engineering characteristic parameter and mass ratio, blocking mass has the highest adaptability but little vibration attenuation, elasticity separated devices has notable attenuation but difficulty to apply in plate and shell support structure, and the frame style structure gives consideration to the both factors, having considerable applied prospect.

Investigation on Vibration Analysis and Evaluation of Multispan Straight Pipes Based on Powerflow Method

Xi Wenbing, Li Pengzhou, Sun Lei, Zhang Kun, Lin Song

2016, 37(S2): 85-88. doi: 10.13832/j.jnpe.2016.S2.0085

Abstract(14) PDF(0)

Abstract:
Piping system is a complex structure with multi-supports, and it is difficult to evaluate the vibration isolation performance of the system with traditional methods. A beam-rectangular-plate model is used to analyze the vibration transmission characteristics of the piping system in this paper. Furthermore, the pipe vibration isolation and its performance evaluation methods are studied with theoretic, numerical and experimental analysis based on vibration power flow theory. The theory analysis shows that the power flow criterion can reveal the information of each mode and dynamic characteristics of the whole system, as well as quantify the vibration isolation efficiency. Such a criterion can be used to estimate the primary and secondary vibration transfer paths and isolation efficiency of the whole system with multi supports.

Vibration Control and Experimental Study of Pipes for Auxiliary System

Li Xin, Liu Tianyan, Lin Song, Zhang Kun

2016, 37(S2): 89-91. doi: 10.13832/j.jnpe.2016.S2.0089

Abstract(35) PDF(0)

Abstract:
Under the excitation of the pump, the pipes of auxiliary system for primary loop have a problem of excessive vibration, and when the vibration is transmitted to the installed base, it may result in serious troubles. To solve this problem, the study on piping vibration control of auxiliary system needs to be carried out. First of all, the finite element model of the pipe for auxiliary system is established and the positions of the supports of the pipe are optimized using the optimization algorithm. Then, using the test method, the analysis on the vibration of the fixed end before and after optimization is carried out. On this basis, the vibration transmitted from the support to the installed base is reduced with Dynamic Vibration Absorber（DVA）. Finally, the optimization scheme of vibration control of the pipe is obtained. And it offers some references for the optimization design of vibration attenuation.

Experimental Study of Multi Frequency Vibration Absorber in Pipe System

Liu Tianyan, Li Pengzhou, Xi Wenbing, Zhang Kun

2016, 37(S2): 92-95. doi: 10.13832/j.jnpe.2016.S2.0092

Abstract(28) PDF(1)

Abstract:
As important engineering structures, the pipe system is widely used in the primary circuit of the reactor. According to the vibration and noise and safety problems in pipeline system, a new type of multi frequency vibration absorber is designed. And the effectiveness of DVA is validated through experiments. In the experiments, the vibration of pipe and the vibration transmission is pipe system is significantly reduced.

Research on Shock Stress Reduction Factor in Shock Stress Evaluation of Stainless Steel Piping

Chen Xuede, Liu Zicai, Zhang Kun, Lin Song, Li Pengzhou, Li Xihua

2016, 37(S2): 96-98. doi: 10.13832/j.jnpe.2016.S2.0096

Abstract(19) PDF(0)

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To study the over conservative margin of shock stress reduction factor in stainless steel piping designed by elasto-plastic rules, a method is used by carrying out elastic and elasto-plastic calculations for stainless steel piping with scaled three kinds of independent loads of gravity, pressure and shock loads, respectively, to obtain nominal stress and actual total strain for manifesting shock load’s less damage effect on stainless steel piping. Comparative analysis results show that shock stress reduction factor 0.25 stipulated in shock codes is of conservative margin, and a new value of 0.2 is proposed for elasto-plastic design. Conclusion is that a new shock stress reduction factor of 0.2 by elasto-plastic design can not only meet the code requirements of conservatism but also reduce the over conservative margin in shock stress evaluation.

Active Control of Vibration with Line-Spectrum of the Blade Pump

Zhang Kun, Xi Wenbing, Li Pengzhou, Sun Hongling, Li Xihua, Liu Tianyan

2016, 37(S2): 99-102. doi: 10.13832/j.jnpe.2016.S2.0099

Abstract(19) PDF(0)

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The control on vibraiton with line spectrum of the blade pump, which is a typical rotate pump, has become the research hotspot in the field of vibration and noise control. On the demand of reducing the periodic line spectrum vibration of the blade pump, this paper studied the method for the line spectrum vibration and noise reduction based on the active vibration control technology. The facility for the vibration test of the blade pump is built to study the characteristics of the periodic line spectrum. Then the line spectrum reduction performance of the approach applying on the test blade pump was verified by the experiment.

Gap Stiffness Value Research in Transient Dynamic Analysis for Piping Model

Huang Wenhui, Li Pengzhou, Chen Xuede, Li Xihua

2016, 37(S2): 103-106. doi: 10.13832/j.jnpe.2016.S2.0103

Abstract(26) PDF(0)

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Set up a geometry nonlinear finite element model consistent with experiment model to calculate shock response of piping under transient load with nonlinear transient dynamic time history method and made comparison between corresponding experiment data and numeric results. By way of this comparison, the exploration study has been done for how to simulate the gap of support and how to confirm the gap stiffness.

Vibration Transmission Analysis of Pipe System for Nuclear Reactor System Based on Transmission Path Analysis Method

Zhang Kun, Peng Liang, Li Pengzhou, Lin Song

2016, 37(S2): 107-110. doi: 10.13832/j.jnpe.2016.S2.0107

Abstract(28) PDF(0)

Abstract:
The noise source identification, qualification and recognition of transmission path are the precondition of the vibration and noise control. In order to meet the engineering requirement of quantitative vibration contribution analysis, the transmission path analysis method was applied to the vibration transmission analysis of the pipe system for nuclear reactor system. By measuring the frequency response function（FRF） of each vibration transmission path, the vibration velocity of exciting points and evaluation points, and estimating the exciting forces, the TPA was performed and the vibration contribution of the facilities and pipes to the evaluation points were obtained. The experiment on a typical pipe system was used to verify the accuracy of proposed method.

Numerical Simulation on Effect of Steam Velocity on Separating Property of Cyclone Separator

Li Yong, Huang Zhen, Yuan Dewen

2016, 37(S2): 111-115. doi: 10.13832/j.jnpe.2016.S2.0111

Abstract(26) PDF(0)

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In the present paper, numerical simulation on separating process of cyclone separator used in the steam generator is performed under conditions of different steam velocity based on two-fluid model and Reynolds Stress Model. The effect of steam velocity on separation process of droplets is analyzed. The simulation results show that the effect of steam velocity on separation property is related with droplets diameter. The effect of steam velocity is significant and separation efficiency increases with the increasing of steam velocity only when the droplets diameter is in a certain range. It is also found that liquid stack will happen on the wall of cyclone separator when steam velocity is small.

Experimental Study on Critical Heat Flux of Rectangular Channel under Condition of Single Plate Heater

Liu Liang, Zhang Yan, Xing Dianchuan, Huang Zhigang

2016, 37(S2): 116-120. doi: 10.13832/j.jnpe.2016.S2.0116

Abstract(30) PDF(2)

Abstract:
The experimental study on critical heat flux of narrow rectangular channel under the condition of single plate heater about upward flow carried on high temperature and high pressures thermal hydraulic test facility was introduced in this paper. The effect of thermal hydraulic parameters such as mass flux and critical quality on CHF in the rectangular channel under the condition of single plate heater had been studied. The results of experimental research showed that: in the range of the test parameters, CHF difference between single plate heater and double plate heater was very little, while effect of quality and mass flux on it was similar. When other parameters kept constant, the CHF of rectangular channel under the condition of single plate heater became lower along with the increasing of critical quality. The CHF became higher along with the increasing of inlet sub-cooling. In the range of lower critical quality, the CHF became higher with the increasing of mass flow flux. However, the opposite trend was observed for higher critical quality. Finally, the formula to predict CHF in rectangular channel under the condition of single plate heater was drawn up, which had perfect results in its prediction scope.

Theoretical Investigation on Thermal Hydraulic Characteristics of Boiling Two-Phase Sodium

Qiu Zicheng, Lan Zhike, Ma Zaiyong, Qiu Suizheng, Zan Yuanfeng, Xing Dianchuan, Li Yongliang

2016, 37(S2): 121-124. doi: 10.13832/j.jnpe.2016.S2.0121

Abstract(21) PDF(0)

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Based on the experimental work, thermal hydraulic characteristics of sodium boiling are theoretically researched. The object of calculation is an annulus. Liquid sodium is considered incompressible while sodium vapor is considered compressible. Homogeneous flow model is used in the two phase region and upwind scheme integral is used during the calculation. The calculated results showed good agreement with the experimental data, moreover, this work shows good predictive ability as expansion of the experiments.

Experimental Analysis of Steam Effect on Hydrogen Combustion in Severe Accidents

Wang Ying, Li Yong, Zan Yuanfeng, Tang Yueming, Zheng Hua, Xie Shijie, Zhang Zhen, Zhang Youjia

2016, 37(S2): 125-128. doi: 10.13832/j.jnpe.2016.S2.0125

Abstract(21) PDF(0)

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This paper investigates the effect of steam concentration on hydrogen combustion in severe accident condition. By changing the initial concentration of steam, combustion temperature, peak pressure, flame velocity and burn-off rate are compared, and experimental results also are compared. These results are concluded that the steam can decrease the combustion temperature, pressure and flame velocity, but has no effect on the burn-off rate.

Experimental Research on Passive Residual Heat Removal System of Small Modular Reactor under SBO

Zhang Yan, Lu Xiaodong, Peng Chuanxin, Bai Xuesong, Zan Yuanfeng, Zhuo Wenbin, Yan Xiao

2016, 37(S2): 129-134. doi: 10.13832/j.jnpe.2016.S2.0129

Abstract(23) PDF(0)

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Based on the design characteristics of the passive residual heat removal system（PRHRS） for small modular reactor, a scaled experimental facility of passive safety system CREST was constructed. A short-term residual heat removal experiment under the station blackout accident（SBO） was performed in the CREST facility, and the cooling capacity and operation characteristics of the PRHRS was studied. The results show that, after the station blackout accident, the PRHRS can be started effectively, in which a stable two-phase natural circulation between the steam generators and the heat exchanger was established with a mass flow of 0.4T/h, thus the core decay residual heat and the sensible heat were removed to the water in the containment water tank（CWT） effectively. The cold water from the core makeup tanks（CMTs） was injected into the reactor pressure vessel for core cooling. During this period, the peaked primary pressure was 16.3 MPa and less than the relief valve opening pressure 16.9 MPa. In addition, the average coolant temperature of the reactor core reduced below 210 ℃, and the operation of the reactor was in safe condition..

Parameter Sensitivity Analysis of Interface Momentum Transfer Model in Two Fluid Model

Zhang Junyi, Yan Xiao, Xiao Zejun, Huang Yanping, Xu Jianjun

2016, 37(S2): 135-141. doi: 10.13832/j.jnpe.2016.S2.0135

Abstract(30) PDF(0)

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Parameter sensitivity analysis of the interface force model and/or its key parameters in the momentum transfer models was carried out with the framework of two-fluid model. The effect of the interface force model and/or its key parameters on the axial and radial distribution of two-phase flow parameters in a vertical round tube under subcooled flow boiling process was studied and compared with the integrated effect experiment data. It was shown that the drag force is with effect on the axial two-phase flow process rather than the radial parameter distribution, and non-drag forces have strong effect on the radial parameter distribution rather than the axial two-phase flow process. In the aspect of non-drag forces, turbulence dispersion force and lift force have a dominant effect on the radial void fraction distribution, especially the peak value of void near the wall. Wall lubrication force mainly affects the peak value of void near the wall. Virtual mass force has little effect neither on the axial nor the radial parameter distribution and can be neglected in the simulation of subcooled boiling process in a round tube.

Experimental Investigations on Interaction of Surface Catalyst and Thermal Hydraulics in Passive Autocatalytic Recombiner

He Yanqiu, Yan Xiao, Sui Xi, Huang Yanping, Zan Yuanfeng, Huang Zhen, Wang Yin

2016, 37(S2): 142-145. doi: 10.13832/j.jnpe.2016.S2.0142

Abstract(25) PDF(0)

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An experimental investigation focusing on the interaction between surface catalytic reaction and thermal hydraulics is carried out. Analysis is conducted on the effects of different inlet velocities and hydrogen concentrations on the chemistry and thermal hydraulics. From the experiment results, it can be found that the distribution of catalytic temperature at first half of the sheet is higher than that of the second half. With the increasing of the inlet velocity, the outlet hydrogen concentration also increases. Relative to the inlet hydrogen concentration, the effect of inlet velocity exerted on outlet temperature and catalytic temperature are not monotonous. As inlet hydrogen concentration increases, outlet hydrogen concentration, along with catalytic temperature would increase therewith.

Investigations on Startup Methods of Large LOCA Blowdown Simulation Experiments

Xing Dianchuan, Tang Ming, Wang Tao, Hou Fengwei, Zan yuanfeng, Huang Jun, Qiu Zicheng

2016, 37(S2): 146-149. doi: 10.13832/j.jnpe.2016.S2.0146

Abstract(23) PDF(0)

Abstract:
The large LOCA blowdown simulation experiment is usually needed for the purpose of the performance evaluation of containment sump strainer and downstream effect analysis. In this paper, large LOCA blowdown simulation experiment was conducted by double rupture discs combining with a pneumatic valve, and the accurate controlling of starting pressure and the instantaneous release of high-energy fluid was realized. The measurement results of dynamic pressure indicate that the pressure lose of double discs bleed starting mode is the largest, and the total pressure rise velocity is relative slow for the single disc starting mode. Double discs charging starting mode can accurately simulate large LOCA blowdown physical process in term of pressure loss, pressure rise velocity and pressure accuracy. Finally, jet impinging destruction tests for double-wall encapsulated insulation configuration were carried out by double discs charging starting mode. The results indicate that the impact load supplied by the present facility is sufficient.

Experimental Research of Separate Effect on Containment Condensation Heat Transfer

Zhang YouJia, Yu Shimo, Zhang Zhen, Bai XueSong, Zan YuanFeng, Zhuo WenBin, Yan Xiao, Wang Ying

2016, 37(S2): 150-155. doi: 10.13832/j.jnpe.2016.S2.0150

Abstract(32) PDF(0)

Abstract:
The effect of condensation heat transfer ability of containment is one of the significant factors on passive safety system by removing residual heat from core. The experimental study of separate effect on the containment condensation heat transfer was conducted, based on the passive containment coolant system of ACP100 K modularize reactor. Coolant energy balance method is applied to obtain the heat flux. The effects of steam temperature, temperature difference between steam and surface, steam mass flow rate, condensation plate orientation and non-condensable gas on condensation heat transfer coefficient were mainly studied. The correlation between steam temperature and condensation heat transfer is obtained by fitting based on the experimental data.

2016 Vol. 37, No. S2