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2014 Vol. 35, No. 5

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Preliminary Discussion on Neutronic Parameters of Inert Matrix Fuels in PWR Environment
Yu Tao, Xie Jinsen, Li Zhifeng, Liu Zijing, Zuo Guoping, He Lihua, Li Xiaohua
2014, 35(5): 1-3. doi: 10.13832/j.jnpe.2014.05.0001
Abstract:
To study the applicability of utilization of Inert Matrix fuels(IMF) in PWR, the variations of infinite multiplication factor kinf, fuel temperature coefficient Dc, moderator temperature coefficient MTC with PuO2 volume fractions in two typical IMF fuels, PuO2+ZrO2+MgO and PuO2+ThO2, are calculated and analyzed. And the preliminary acceptable design regions of IMF fuels composition to satisfy the negative Dc and MTC are obtained.
Coarse-Mesh Nodal Methods with the Capability to Explicitly Handle the Material Heterogeneity in the Axial Direction of a Fuel Assembly
LÜ Dong, Zhang Shaohong
2014, 35(5): 4-8. doi: 10.13832/j.jnpe.2014.05.0004
Abstract(11) PDF(0)
Abstract:
The incapability to handle the heterogeneity introduced by spacer grid and partially-inserted control rod has long been considered as one of the noticeable defects for the conventional coarse-mesh nodal methods. To improve this defect, two new nodal methods with the capability to explicitly handle these heterogeneities in the framework of coarse-mesh nodal methods are proposed. Numerical results for IAEA 3D benchmark problem and the practical power reactor problems demonstrate that the proposed sub-mesh method is quite successful, it is able to effectively handle not only the partially inserted control rod, but also the fine spacer grid within an axial coarse mesh.
Application of Discrete Ordinate and Monte-Carlo Coupling Method for Reactor Shielding Calculation
Xiao Feng, Ying Dongchuan, Zhang Chunwei, LÜ Huanwen, Li Lan
2014, 35(5): 9-12. doi: 10.13832/j.jnpe.2014.05.0009
Abstract(10) PDF(0)
Abstract:
A coupling calculation method based on the discrete ordinate method code DOT and Monte-Carlo method code MCNP was realized. By automatically providing a binary source specification file for the surface source function of MCNP(i.e. SSR command), this coupling method was achieved and subsequently the necessity of re-compiling of MCNP code was eliminated. This coupling method was applied in the shielding problem of rooms around the pit of reactor cavity and a good agreement was obtained between the calculation and measurement results, which validated the correctness of this coupling method. Further more, source bias method was implemented in this coupling method, which shows great efficiency in variance reduction and the improvements of calculation efficiency.
Preliminary Research on Elimination of OBE in Seismic Design Requirements for NPPs
Li Qiang, Zhang Jian
2014, 35(5): 13-16. doi: 10.13832/j.jnpe.2014.05.0013
Abstract:
Literatures and reports by US NRC and EPRI are reviewed and the statistical data of stress ratios of some class 1 pipes are analyzed to demonstrate the reasons of elimination of OBE from the design basis of NPPs. It is reasonable to decrease the ratio of OBE to SSE, to eliminate OBE from the loading combinations, and to use OBE only as a limit to shutdown the nuclear power plants in earthquake, which can optimize the seismic design. It is shown that measures shall be taken to maintain overall safety level against earthquake.
Analysis of Natural Circulation and Creep Damage under Station Blackout Severe Accidents
Xiang Qingan, Deng Chunrui, Chen Baowen, Feng Jinjun
2014, 35(5): 17-21. doi: 10.13832/j.jnpe.2014.05.0017
Abstract(11) PDF(0)
Abstract:
The natural circulation model of ACP1000 Nuclear Power Plant is built using MELCOR 2.1. This paper analyzes the natural circulation phenomena in the hot leg and steam generator tube by selecting TMLB’ accident, and uses the cumulative creep damage to determine the relative creep-rupture timing in the reactor coolant pressure boundary components. The results showed that RPV outer pipe would be failed earlier than the flawed steam generator hottest tube.
A Modified Wake Oscillator Model for Predicting Vortex Induced Vibration of Heat Exchanger Tube
Feng Zhipeng, Zang Fenggang, Zhang Yixiong, Ye Xianhui
2014, 35(5): 22-27. doi: 10.13832/j.jnpe.2014.05.0022
Abstract:
Base on the classical wake oscillator model, a new modified wake oscillator model is proposed, for predicting vortex induced vibration of heat exchanger tube in uniform current. The comparison between the new wake oscillator model and experimental show that the present model can simulate the characteristics of vortex induced vibration of tube. Firstly, the research shows that the coupled fluid-structure dynamical system should be modeled by combined displacement and acceleration mode. Secondly, the empirical parameter in wake oscillator model depends on the material properties of the structure, instead of being a universal constant. Lastly, the results are compared between modified wake oscillator model and fluid-structure interaction numerical model. It shows the present predicted results are compared to the fluid-structure interaction numerical data. The new modified wake oscillator model can predict the vortex induced heat exchanger tube vibration feasibly.
Study on Seismic Margin of Protection System Cabinet for Nuclear Power Plants
Hu Xiaoying
2014, 35(5): 28-30. doi: 10.13832/j.jnpe.2014.05.0028
Abstract:
This paper takes the protection system cabinet in Qinshan Nuclear Power Plant as an example, based on the existing required response spectrum and test response spectrum of functional component inside cabinet and cabinet frame and enclosure, an easy CDFM(Conservative Deterministic Failure Margin) analysis method mentioned in EPRI NP-6041-SL technical report is adopted to calculate the seismic margin earthquake scale factor through parameters’ selection such as clipping factor, effective cabinet amplification factor, knockdown factor and so on to find seismic margin of existing protection system cabinet.
Structural Evaluation Method Study and Procedure Development for Pressurizer Surge Line Subjected to Thermal Stratification Phenomenon
Zhang Yixiong, Yu Xiaofei, ai Honglei
2014, 35(5): 31-35. doi: 10.13832/j.jnpe.2014.05.0031
Abstract:
Thermal stratification phenomenon of pressurizer surge line can lead potential threaten to plant safety. Base on the mechanism of thermal stratification occurrence, Fr number is used to judge whether the stratification occurs or not. Also the method of calculating heat transfer coefficient is investigated. Theoretically the 3-dimension thermal stress induced by thermal stratification is decoupled to 1-dimension global stress and 2-dimension local stress, and the complex 3-dimention problem is simplified into a combination of 1-dimension and 2-dimension to compute the stress. Comply with criterion RCC-M, the complete structure integrity evaluation is accomplished after combining the stress produced by thermal stratification and the stresses produced by the other loadings. In order to match the above combined analysis method, Code SYSTUS and ROCOCO are developed. By means of aforesaid evaluation method and corresponding analysis program, surge line thermal stratification of Qinshn Phase II Extension project is investigated in this paper. And the results show that structural integrity of the pressurizer surge line affected by thermal stratification still satisfies criterion RCC-M.
Study on Response of Coil Current for Control Rod Drive Mechanism
Liu Sen, Li Yuezhong, Zhao Maomao, Sun Zhenguo, Zhang Yifei
2014, 35(5): 36-38,52. doi: 10.13832/j.jnpe.2014.05.0036
Abstract:
The lift and withdraw of Control Rod Drive Mechanism(CRDM) need three coils working together, which demands a strict process of coil current’s dynamic response. The paper built a rod control system and its equivalent circuit by Simulink, calculated the influence of coil current response time from the aspects of coil resistance inductor, voltage and other factors, and simulated the current in moving coils by MAGNET. Finally, the paper concluded with the influence on CRDM coil current response time by coil voltage, coil equivalent inductance, resistance and rod control circuit.
Research on Reactor Power Controller Based on Artificial Immune P& PID Cascade Control Technology
Cheng Shouyu, Peng Minjun, Liu Xinkai
2014, 35(5): 39-42. doi: 10.13832/j.jnpe.2014.05.0039
Abstract(18) PDF(0)
Abstract:
The Reactor Power control system usually adopts the traditional PID controller, the traditional PID controller can meet the operating requirements, but the control effect is not very good. In order to improve this condition, the paper proposes an immune P&PID cascade controller which based the immune mechanism of B-cell co-operating with T-cell, the nuclear power controller based on artificial immune is less reported. In order to verify &validate the control strategy, the designed controller debugs with the full-scope real-time simulation system of nuclear power plants. The simulation results shows that the immune controller can effectively improve the dynamic operating characteristics of the reactor system, and the immune controller is superior to the traditional PID controller in control performance.
Study on Correction of Reactor Measurement System Based on Digital Technology
HE Zhengxi, Chen Jing, Huo Yujia, Yu Junhui, He Peng, Li Xiaofen, Gou Tuo
2014, 35(5): 43-46. doi: 10.13832/j.jnpe.2014.05.0043
Abstract(11) PDF(0)
Abstract:
According to analyzing all the factors which affect the accuracy of measurement, instrument correction and system correction are proposed in reactor measurement systems. The two correction methods can be implemented by digital system, and then, the measurement accuracy on transient and post-accident conditions are promoted and the usage of instrument is extended, as a result, the safety and economy of plant are improved.
Study on Circuit Simulation Model of Instrument Survivability Assessment in Severe Accident in Nuclear Power Plants
Huang Youjun, Chen Zhi, Zou Shuliang, Yu Junhui, Kong Xiangcheng
2014, 35(5): 47-52. doi: 10.13832/j.jnpe.2014.05.0047
Abstract(10) PDF(0)
Abstract:
The method of enveloping is used commonly in the instrument survivability evaluation in severe accident in nuclear power plants(NPPs). Due to the limitation of this method, this paper studies the method of circuit simulation by PSpice as complementary. Based on the databases of phenomenon and effects on instruments in severe accident, we analyze and summarize the key condition factors that threats most. And according to the characteristics of instruments in NPPs, we create the circuit simulation models that present the instruments in NPPs. Comparing the simulation results with the survivability of instruments in TMI accident, the result shows that the model is reasonable.
Design and Simulation of Passive Residual Heat Removal System for Nuclear Power Plants
Yuan Xiao, Peng Minjun, XiA Genglei, Liu Xinkai
2014, 35(5): 53-56. doi: 10.13832/j.jnpe.2014.05.0053
Abstract:
The passive residual heat removal system(PRHRS) can work for a long period of time to achieve its function by its natural cycle characteristics, ensuring the reactor safety. To meet this requirement, A type of passive residual heat removal system(PRHRS) is designed, the emergency cooling water tank is worked as an intermediate buffer device, ensuring the rapid cooling in the early stage of the accident and the PRHRS could work reliably for a long period of time. Based on the natural circulation characteristics, design calculation gave a steady-state solution. The RELAP5 code was used to analyze the operation characteristics of the PRHRS and the transient characteristics of the primary loop system affected by the PRHRS. The results show that: through rational design, the residual heat can be effectively removed by natural circulation in the PRHRS, guaranteeing the security.
Experimental Research of Film Separation in a Wave-Plate Channel
Liu Xiaoyi, Tian Ruifeng, Chen Junliang, SuN Lanxin, Yan Changqi
2014, 35(5): 57-61. doi: 10.13832/j.jnpe.2014.05.0057
Abstract:
The visualization research experiment platform was designed and built to describe the rupture of falling films driven by a horizontal gas flow in the wave-plate channel in this paper. The critical separation condition of different film thickness was gained by changing the liquid film flow rate and air velocity. The high speed camera was used to get the film separation images. The results showed that the liquid film rupture associated with both air velocity and film thickness which showed a negative correlation; Dimensionless analysis showed that the inertial centrifugal force and air flow shear stress are instability factors leading to the film separation, viscous force and surface tension are the stability factors; The film breach was started from the bending angle(convex angle) of the wave-plate, the separation forms related to the thickness of liquid films.
Heat Transfer Performance of Heat Pipe for Passive Cooling of Spent Fuel Pool
Wang Minglu, Xiong Zhenqin, Gu Hanyang, YE Cheng, Cheng Xu
2014, 35(5): 62-65. doi: 10.13832/j.jnpe.2014.05.0062
Abstract:
A large-scale loop heat pipe has no electricity driven component and high efficiency of heat transfer. It can be used for the passive cooling of the SFP after SBO to improve the safety performance of nuclear power plants. In this paper, such a large-scale loop heat pipe is studied experimentally. The heat transfer rate, evaporator average heat transfer coefficient, operating temperature, operating pressure and ammonia flow rate have been obtained with the water flow ranging from 0.007m/s to 0.02m/s outside the evaporator section, heating water temperature in the range of 50 to 90℃, air velocity outside the condensation section ranging from 0.5 to 2.5 m/s. It is found that the heat transfer rate reaches as high as 20.1 kW. Parametric analysis indicates that the heat transfer rate and ammonia flow rate are influenced significantly by hot water inlet temperature and velocity, while beyond 1.5m/s, the effect of air velocity outside the condensation section is minor.
Research of Supercritical Water Flow Instability under Natural Circulation Based on Factorial Analysis
Li Jingjing, Zhou Tao, Huo Qijun, Xiao Zejun
2014, 35(5): 66-69. doi: 10.13832/j.jnpe.2014.05.0066
Abstract:
The supercritical water flow instability under natural circulation is important to the safety of the reactor. By the method of factorial analysis, the effects of different factors and the factor interaction on the natural circulation stability boundary are computed. The results show that, for the steady state mass flow, the inlet resistance coefficient has the biggest percentage contribution rate about 70.89%. The next is the interaction of heating zone length and inlet temperature, and its percentage contribution rate is about 13.26%. The third is the heating zone length, and its percentage contribution rate is about 12.32%. For the oscillation period, the heating zone length has the biggest percentage contribution rate about 68.47%, the next is the inlet resistance coefficient, and its percentage contribution rate is about 24.04%. The effect of other factors and factor interaction on the steady state flow and oscillation period are negligible.
Application and Evaluation of APROS to Supercritical Flow Instability
Li Yan, Lu Daogang, Zeng Xiaokang, Liu Yu
2014, 35(5): 70-73,88. doi: 10.13832/j.jnpe.2014.05.0070
Abstract(11) PDF(0)
Abstract:
Considering the possible flow instabilities in the supercritical Water-Cooled Reactor(SCWR), APROS has been applied to three different cases of density wave oscillations. The two-parallel channels, single channel and natural circulation loop are all numerical modeled and stability boundaries are obtained by dynamic simulation. Results show that the software APROS is capable of predicting the supercritical stability boundaries, which agree with other experimental and numerical results. For numerical analysis the time step should be refined. A large time step would bring along dissipative effects.
Experimental Investigation of Air Bubble in Water through a Vertical Narrow Rectangular Channel
Song Mingliang, Huang Yanping, Wang Junfeng, Liu Guangxu, Zhang Liqin, Zhang Xingwu
2014, 35(5): 74-77. doi: 10.13832/j.jnpe.2014.05.0074
Abstract:
This paper presents the visualized investigation of air bubble motion in stagnant water through a vertical narrow rectangular channel with a cross section in 2mm×60 mm, The path and shape of different area equivalent diameter was observed through the experiment. The relationship between the rising velocity and area equivalent diameter was analyzed quantitatively, and finally the cap and slug bubble rising terminal velocities based on this experiment result were compared with the correlations in literature quantitatively.
Effect of Bubble Interface Parameters on Predicted of Bubble Departure Diameter in a Narrow Channel
Xu Jianjun, XiE Tianzhou, Zhuo Wenbin, Chen Bingde, Huang Yanping
2014, 35(5): 78-82. doi: 10.13832/j.jnpe.2014.05.0078
Abstract:
The predicted model on the bubble departure diameter in a narrow channel is built by analysis of forces acting on the bubble, and effects of bubble interface parameters such as the bubble inclination angle, upstream contact angle, downstream contact angle and bubble contact diameter on predicted bubble departure diameters in a narrow channel are analysed by comparing with the visual experimental data. Based on the above results, the bubble interface parameters as the input parameters used to obtain the bubble departure diameter in a narrow channel are assured, and the bubble departure diameters in a narrow channel are predicted by solving the force equation. The predicted bubble departure diameters are verified by the 58 bubble departure diameters obtained from the vertical and inclined visual experiment, and the predicted results agree with the experimental results. The different forces acting on the bubble are obtained and the effect of thermal parameters in this experiment on bubble departure diameters is analysed.
Effects of Inclination and Rolling on Interfacial Parameter Distributions of Bubbly Flow in a Rectangular Duct
Yan Chaoxing, Yan Changqi, SuN Licheng, Xing Dianchuan, Wang Yang
2014, 35(5): 83-88. doi: 10.13832/j.jnpe.2014.05.0083
Abstract:
Effects of inclination and rolling on lateral distribution of interfacial parameters for bubbly flow were studied experimentally with the help of a high-speed camera. Local parameters such as bubble proportion, void fraction and interfacial area concentration(IAC) were obtained in the experiments, showing a similar character with each other. These local parameters change slightly in the central part of the duct and present peaks around positions of xi/(w/2)=±0.5(xi represents the distance from origin based on the central axis of wide side to the inner wall surface of the narrow side, w denotes the wide side) in vertical position for both motionless and rolling cases. The peak of local parameters near the lower wall region is weakened and that near the upper wall is enhanced with an increase in inclined or rolling angles. There exist no obvious differences of interfacial parameters in lateral distribution at the same angle under inclined and rolling conditions within the range of experimental rolling parameters, which is mainly due to that the additional inertial force in lateral direction induced by rolling motion is far more less than that of buoyancy.
Experimental and Numerical Study on Natural Circulation of Integrated Reactor under Inclination Conditions
Gong Houjun, Yang Xingtuan, Huang Yanping, Jiang Shengyao, Liu Zhiyong
2014, 35(5): 89-93. doi: 10.13832/j.jnpe.2014.05.0089
Abstract:
A series of experiments of single phase natural circulation under inclination conditions were performed using the test facility of integrated reactor and followed RELAP5 numerical analysis. The result shows that RELAP5MOD3.2 can accurately predict the mass flow rate of natural circulation under inclination. Mass flow rates of primary side of heat exchangers showes a different variation trend when lateral inclination, mass flow rate of the higher heat exchange is larger than that of lower heat exchanger. The larger the deviation angle of heat exchangers and heaters in vertical direction, the greater the difference of mass flow rates between heat exchangers. The mass flow rates of each section changed in the same way when the longitudinal inclination and the mass flow rate decreased dramatically as inclination angle increased. The total natural circulation mass flow rates of lateral and longitudinal inclination in the same angle are very close.
Research on Experiment Evaluation Method for Thermal Ratchet of Nuclear Equipment at CPR1000 Nuclear Power Station
Wu Shijian, JiN Ting, Xiong Guangming, Liu Le
2014, 35(5): 94-96. doi: 10.13832/j.jnpe.2014.05.0094
Abstract:
For the question that RCC-M criteria can not make a security assessment for the ratchet phenomenon of some components, the experience analysis method of thermal ratchet was introduced, and a more detailed thermal ratchet analysis of the electrically heated pressurizer spray nozzle at the CPR1000 nuclear power plant was presented by the Efficiency Design Curve method and the Ratio Curve method. The results achieved indicate that the RCC-M thermal ratchet evaluation criteria are too conservative and the more accurate experience analysis method can improve the economics of nuclear power construction.
Evaluation and Optimization of Ventilation Systems of Control Rods in Nuclear Power Plants
Cao Nian, Zhang Yan, Wen Yan, JiA Chuan, Xiong Wanyu
2014, 35(5): 97-100,137. doi: 10.13832/j.jnpe.2014.05.0097
Abstract:
In order to evaluate the security of the system and optimize its limit value, the characteristics of the ventilation system is analyzed by comparing the CFD calculation results and the experimental parameters. The results show that the increasing of the control rods is beneficial to both the uniform distribution of the air flow and the cooling efficiency of the system, which promotes the operation safety of the control rod drive mechanism. Although the outlet temperature of the ventilation system is a key index as the cooling efficiency, the number and distribution of the control rods should be considered together. The limit value of the outlet temperature should be changed as the control rod is added.
Containment Test in Area of High Latitude and Low Temperature
Cai Jiantao, Ni Yongsheng, JiA Wutong
2014, 35(5): 101-105. doi: 10.13832/j.jnpe.2014.05.0101
Abstract(14) PDF(0)
Abstract:
The effects of high latitude and low temperature on containment test are detailed analyzed from the view of design, equipment, construct and start-up, and the solution is put forward. The major problems resolved is as below: the effects of low temperature and high wind on defect inspection of the containment surface, the effects of test load on the affiliated equipment of containment in the condition of low temperature, and the effects of low temperature on the containment leak rate measurement. Application in Hongyanhe Unit 1 showed that the proposed scheme can effectively overcome the influence of adverse weather on the containment test.
Study on RCP Coupling Interference Assembling of CPR1000 Nuclear Power Plant
Wang Yuxu, Man Xiaoyu, YuE Kai, Liu Yiliang, Liu Yu
2014, 35(5): 106-108. doi: 10.13832/j.jnpe.2014.05.0106
Abstract(12) PDF(0)
Abstract:
Briefly introduce the CPR1000 main coolant pump(RCP) coupling assembly process, and analyzed the existing problems in the implementation process especially the disparity induced by the axial expansion. The improvement measures which primarily contain the domination of temperature and depth of the assembly are proposed and carried out the field application, and the expected effect is achieved.
Design and Research on New Type Mixing Vanes of Grids
Chen Jie, LEi Tao, Peng Yuan, Gu Mingfei
2014, 35(5): 109-112. doi: 10.13832/j.jnpe.2014.05.0109
Abstract(12) PDF(0)
Abstract:
Grids are the important parts which have important influence on the thermal-hydraulic performance in fuel assembly and the mixing vanes of grids mix the fluid. Focused on the mixing effect of the mixing vanes to fluid, Computational Fluid Dynamic(CFD) method is used to research wherever the mixing is weak inside or outside the subchannels in this paper. The results show that larger size of the mixing vanes can enhance the mixing capability of grids, and the new type design of mixing vanes with assistant vanes can reduce the asymmetry of mixing caused by main vanes only, so as to tone up the vortex mixing strength inside the subchannels. The optimized distribution of assistant vanes will not weaken the cross mixing strength between two adjacent subchannels so much, and is helpful to the development of mixing effect axially. Meanwhile, the additional pressure drop of grids has also been considered.
Development of PWR Passive Autocatolytic Hydrogen Recombiners
Wang Hongqing, MA Weigang, Jiang E, MA Yuandong, Wang Chun, Fu Shengwei, Li Zhiming, Qiu Tian
2014, 35(5): 113-116. doi: 10.13832/j.jnpe.2014.05.0113
Abstract:
Passive autocatalytic hydrogen recombiners(PAR) are mainly used for removing hydrogen in the containment of NPS and keeping the hydrogen concentration at explosion-safe level under severe accident. The PAR is designed according to the theory that catalytic reaction of H2 and O2, the catalytic plate of PAR is made of tPt\Pd catalyzer. According to requirements of the hydrogen removal under NPS severe accidents, put up series experiments on the PAR under the conditions of the different pressure、hydrogen concentration、temperature and The influence test of the different poisons on the catalytic plate and Verification Test of Start and Stop Threshold。The results of performance test indicate that the developed PAR meet the requirements of the NPS hydrogen removal, the development PAR can direct apply the GRE-Ⅱ NPS and the ERP、AP1000 NPS.
Fault Mechanism Analysis of Single Loop Flow Deviation in PWR Nuclear Power Plants
Wang Chuang, Xiong Dongqing, Xu Guangzhen, Zhu Jie, Li Juan
2014, 35(5): 117-119. doi: 10.13832/j.jnpe.2014.05.0117
Abstract(11) PDF(0)
Abstract:
The 3rd Ring Rd PWR repeated some conditions such as single loop flow deviation in power operation, by the qualitative analysis of the possibility and rationality of fault mechanism, and combined with the similar foreign units experience feedback. The author concluded that the single loop flow deviation mostly is caused by the measurement factors, and nuclear power stations can carry out the fault analysis and confirmed by test and measurement data during the unit overhaul.
Analysis and Research of HONGYANHE 1# PZR Pressure’s Closed-Loop Control Circuit Disturbance Test in HFT
Liu Daoguang, Liu Shuangjin, Luan Zhenhua, Chou Shaoshuai, Feng Guangyu
2014, 35(5): 120-123. doi: 10.13832/j.jnpe.2014.05.0120
Abstract:
Analyze the regulator pressure control principle of the Hongyanhe unit 1. Analyze and study the disturbance test results of the PZR pressure closed-loop control loop in HFT, which include +0.1,-0.1, +0.5,-0.5 MPa variation. According to the phenomenon not conforming to the acceptance criteria, put forward the optimization scheme after careful analysis. Optimize the pressure control loop by adjusting the PID differential parameters and the retrace tolerance of ON/OFF heater to get satisfactory results. Compare the Hongyanhe 1# test result with the results of Ningde and Ling’ao to gain rich experience for HPT and the subsequent unit. The disturbance test on the regulator pressure closed-loop control loop is of great significance to HPT and the transient test from fuel loading to commercial operation.
Determination of Experimental Aerosols for Filtered Containment Venting System and Selection of Technical Parameter
Zhou Xiafeng, Gu Haifeng, Li Fu
2014, 35(5): 124-127. doi: 10.13832/j.jnpe.2014.05.0124
Abstract:
In order to perform the aerosol removal efficiency tests of the containment filtered venting system, this paper focuses on the selection of the experimental aerosols for the research. Firstly, the characteristics of the aerosols in the containment are analyzed and the variation of the aerosol characteristics with time is calculated using several computational procedures. Then, on the basis of relevant research experiences of different countries and the special situation of this research, barium sulphate and titanium dioxide are finally selected as the experimental aerosols for this research with a mass median diameter of 1 micron, the system pressures of 1 to 6.5 bar, mass concentration of 50~900 mg/m3, geometric standard deviation of size distribution of 1~2.
A Fault Diagnosis Method Based on Simulation of Real Conditions
Chen Yongwei, Wang Renxiang
2014, 35(5): 128-132. doi: 10.13832/j.jnpe.2014.05.0128
Abstract(13) PDF(0)
Abstract:
This paper proposed a new method of fault diagnosis for instrumentation and control system based on the simulation of real conditions. The first step was to establish a simulation system, in which the logic was consistent with that of the real system. Then signals in the real conditions were sampled as the source of the simulation system and executed in the operator of the simulation system. It utilized Eigen value comparison and wavelet transform to evaluate the deviation between the signal in real system and that in simulation system. The fault was detected based on the comparison between the derived deviation and the threshold by setting or experience. The efficacy of the methodology was demonstrated by implementation and validation in the field.
Study on PCI under Condition Ⅱ Transients for Fuel Rod
Liu Zhenhai, Zhou Yi, Guo Xingkun, Zhang Kun, XiE Qingqing, Gu Mingfei
2014, 35(5): 133-137. doi: 10.13832/j.jnpe.2014.05.0133
Abstract:
The PCI evaluation methodology for Condition Ⅱ transients and thermal-mechanical theoretical model are introduced. The PCI evaluation for the decreasing power operation fuel management of Hainan NPP is performed. The analysis for the PCI margin factors is also carried out. The primary analysis shows that: there are comfortable margins comparing strain energy density of cladding with PCI technological limit value during all the transients; Higher local linear heat generated rate during transients and deeper local burnup before transients will induce lower margin for PCI; the longer decreasing power time before transient is, the lower margin is; Increasing power after decreasing power will increase margin in a certain extent.
Study on Effect of Flow Blockage at Inlet of Plate-type Fuel Element on Thermal-Hydraulic Characteristics of Reactor Core
Li Xiaorong, Peng Shinian, Bi Shumao
2014, 35(5): 138-142. doi: 10.13832/j.jnpe.2014.05.0138
Abstract(11) PDF(0)
Abstract:
This paper simulated the local flow blockage accident of reactor core made up of plate-type fuel with more detailed consideration of local feedback effect between thermal-hydraulics and neutron kinetics, which will help the analysis of the effect of blockage on the reactor thermal-hydraulic characteristics more practically. The simulation shows that the local blockage will cause strong feedback between neutron kinetics and thermal-hydraulics, which will lead to power decrease in the blocked channel. The fuel centreline temperature, the cladding surface temperature and the coolant average temperature will increase due to the deterioration of cooling in the blocked channel.
Model Development of UO2-Zr Dispersion Plate-Type Fuel Behavior at Early Phase of Severe Accident and Molten Fuel Meat Relocation
Zhang Zhuohua, Peng Shinian, Yu Junchong
2014, 35(5): 143-147. doi: 10.13832/j.jnpe.2014.04.0143
Abstract:
According to former study on oxygen diffusion, Nb-Zr solid reaction and UO2-Zr solid reaction, the models of oxidation, solid reaction in fuel meat and relocation of molten fuel meat are developed based on structure and material properties of UO2-Zr dispersion plate-type fuel. The new models can supply theoretical elements for the safety analysis of the core assembled with dispersion plate-type fuel under severe accident.
Development of A Nuclear Power Plant Simulator for Design and Verification of Instrumentation and Control Systems
Li Yankai, LiN Meng, Yang Yanhua, Liu Bin
2014, 35(5): 148-152. doi: 10.13832/j.jnpe.2014.05.0148
Abstract(10) PDF(0)
Abstract:
An engineering nuclear power plant simulator was developed aimed to provide a close-loop analysis tool during the design of new Instrumentation and Control(I&C) systems. Firstly, a simulation platform with a distributed and parallel computing architecture was developed based on.NET environment. Different functional modules, mainly including the thermal-hydraulic module, the control system module and the human-machine interface module, were integrated in the platform to complete the complex model design. Then, based on the simulation platform, a pressurized water reactor simulator was built. Taking RRC Design Manual as a reference, the performance of the simulator, especially the performance of I&C systems, was evaluated and modified. The final result of the simulator is qualitative accord with the RRC Design Manual and the steady value agrees well with the RRC Design Manual before and after transients.
Experimental Study on Local Two Phase Distributions in ERVC Flow Channel
Li Yongchun, Liu Xiaojing, Cheng Xu
2014, 35(5): 153-156. doi: 10.13832/j.jnpe.2014.05.0153
Abstract(10) PDF(0)
Abstract:
The two-phase flow distribution in the external reactor vessel cooling flow channel shows a significant local feature because of its particular flow structure. In this paper, a slice geometry test section and a 1:1 height scaling experimental apparatus is used to simulate the ERVC flow channel. Air is injected in the test section to simulate the two phase flow phenomena and conductivity probe is used to measure the local void fraction distribution. The test results show that the local void fraction transits from the wall peak distribution to the near-wall peak distribution, and eventually develops into the center peak distribution. The air flow rate has a significant effect on the local void fraction distribution in the flow channel.
Method of Characteristics Direction Probabilities and Its Accuracy and Performance Models
Liu Zhouyu, Wu Hongchun, Brendan Kochunas, Benjamin Collins, Yunlin Xu, Thomas Downar
2014, 35(5): 157-163. doi: 10.13832/j.jnpe.2014.05.0157
Abstract:
The method of characteristics direction probabilities combines the geometry flexibility of the method of characteristics and the computing efficiency of the collision probability method. An angular depended boundary averaging is proposed to further improve the efficiency. After that, an accuracy model for the boundary angular flux is introduced which would be used to find the best boundary averaging method. And then, a performance model which explicitly compares the performance of the method of characteristics probabilities to the method of characteristics is given. The numerical results show that model given is correct and the method of characteristics direction probabilities gets great benefits.
High-Performance Whole Core Pin-by-Pin Calculation Based on EFEN-SP3 Method
Yang Wen, Zheng Youqi, Wu Hongchun, Cao Liangzhi, Li Yunzhao
2014, 35(5): 164-167. doi: 10.13832/j.jnpe.2014.05.0164
Abstract(10) PDF(0)
Abstract:
The EFEN code for high-performance PWR whole core pin-by-pin calculation based on the EFEN-SP3 method can be achieved by employing spatial parallelization based on MPI. To take advantage of the advanced computing and storage power, the entire problem spatial domain can be appropriately decomposed into sub-domains and then assigned to parallel CPUs to balance the computing load and minimize communication cost. Meanwhile, Red-Black Gauss-Seidel nodal sweeping scheme is employed to avoid the within-group iteration deterioration due to spatial parallelization. Numerical results based on whole core pin-by-pin problems designed according to commercial PWRs demonstrate the following conclusions: The EFEN code can provide results with acceptable accuracy; Communication period impacts neither the accuracy nor the parallel efficiency; Domain decomposition methods with smaller surface to volume ratio leads to greater parallel efficiency; A PWR whole core pin-by-pin calculation with a spatial mesh 289×289×218 and 4 energy groups could be completed about 900 s by using 125 CPUs, and its parallel efficiency is maintained at about 90%.
Calculation of Fatigue Cumulative Usage Factor for Nuclear Equipment under In-Service Environment
Liu Pan, Chen Rong, Wu Shijian
2014, 35(5): 168-171. doi: 10.13832/j.jnpe.2014.05.0168
Abstract:
Calculation of nuclear equipment design life should consider the influence in service environment. Because the fatigue curves in current regulation do not take into account the impact of in-service environment, the fatigue cumulative usage factor can be modified by the environmental fatigue correction factor. During the correcting, three kinds method have been proposed. Based on above different methods, the fatigue cumulative usage factor has been corrected separately. Meanwhile, the results have been contrasted with each other and the results under air environment. The results showed that the fatigue cumulative usage factor bigger than it under air environment. Furthermore, parameter transformation of environmental fatigue correction factor with results of thermal-structure field calculation more conservative than with the results of transient combination.
Determination of Separation Efficiency in Wire Mesh Mist Eliminator by CFD
SHen Shengqiang, Zhen Ni, Mou Xingsen
2014, 35(5): 172-177. doi: 10.13832/j.jnpe.2014.05.0172
Abstract:
On the assumption of the staggered array model, a numerical simulation of the vapor flow field in wire mesh mist eliminator along with the mechanism for droplet capture due to inertial impaction is presented in this paper. The efficiency of a single wire in the eliminator is computed in order that the efficiency of wire mesh mist eliminator can be calculated. The obtained efficiency is found to be within a reasonable agreement with the published literature data. The effect of wire diameter, pad thickness, packing fraction on the separation efficiency and the relation between Stk and the efficiency of a single wire is investigated.
Classification of Nuclear Power Plant Items and Quality Requirements on Design Extension Items
SuN Zaozhan, SHen Wei, Huang Bingchen, Deng Dong
2014, 35(5): 178-181. doi: 10.13832/j.jnpe.2014.05.0178
Abstract(18) PDF(0)
Abstract:
Adequate safety classification for nuclear power plant items is an important means to ensure good safety and economic performances of the plants. Classification theories and methods further develop with the continuous improvements in nuclear safety goals and plant design philosophy. It becomes a consensus that future nuclear power plants should be explicitly designed against certain severe accidents though their occurrences are considered extremely improbable, and therefore, the quality requirements on equipment expected to function under "beyond design basis" accident conditions becomes a focused topic of discussion.Considering both domestic and international experience, as well as the higher safety goal required for China’s new nuclear power plants and related development in other countries, relevant modifications are p roposed to be made to the current regulations and standards, and further, a set of equipment quality requireme nts is recommended.
Schedule Management of Nuclear Island Design of First Kind of AP1000 Unit
Liu Xiaoheng
2014, 35(5): 182-184. doi: 10.13832/j.jnpe.2014.05.0182
Abstract(16) PDF(0)
Abstract:
Based on the schedule management for the first reactor of advanced passive pressurized water reactor(AP1000), this paper states the major problems under the complicated contractual relationships, focusing on the design of first reactor and the first-time manufacture of primary equipment as well as the modular construction, combined with the actual situation of Sanmen nuclear power project construction, and discusses and analyzes the major challenges and difficulties that the first AP1000 nuclear island design imposed on the scheduling management. A series of countermeasures is taken to minimize the impact on schedule delay of the design of first reactor. It also intends to put forward, in view of the experience and lessons learned in Sanmen nuclear power project construction, some suggestions for the schedule management of the future AP1000 projects.