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Top Fuel 2016: LWR Fuels with Enhanced Safety and Performance

作者： Yifei, Miao Yongjun, Jiao Kun, Zhang Shuo, Xing Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Nuclear Power Institute of China China

ISBN: (纸本)9780894487309

As a new kind of Zr-Sn-Nb series alloy, N36 has not been explored in irradiation growth behavior before. In this paper, four empirical correlations including power, logarithmic, exponential and hyperbolic tangent law were used to build irradiation growth model of N36 zirconium alloy preliminarily. Before that, lengths of the fuel rods with N36 claddings from poolside measurement were analyzed to get irradiation growth strains, which were then used to fit the four empirical correlations mentioned above. Distribution of fast fluence along axial direction of tubes was considered in all irradiation growth models. The fitting results showed that the hyperbolic tangent law fit irradiation growth strains the best, while power law did the worst. In order to improve the precision of the hyperbolic tangent model, several improvements were done. Verification and validation of the improved hyperbolic tangent irradiation growth model suggested that the size of second phase may have an influence on irradiation growth behavior of N36 tubes.

关键词： Zirconium alloys

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Fuel assembly design for supercritical water-cooled reactor

Fuel assembly design for supercritical water-cooled reactor

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作者： Linna, Feng Fawen, Zhu Science and Technology on Reactor System Design Technology Laboratory Third Section of Huafu Road Huayang Town Shuangliu County Chengdu Sichuan Province610213 China

The supercritical water-cooled reactor (SWCR) has been selected as one of the most promising reactors for Generation IV nuclear reactors due to its higher thermal efficiency and more simplified structure compared to the state-of-the-art light water reactors (LWRs). However, there are a large number of potential problems that must be addressed, particularly the fuel assembly design of the SCWR. SCWRs are a kind of high-temperature, high-pressure, water-cooled reactor that operates above the thermodynamic critical point of water (374°C, 22.1 MPa). Corrosion and degradation of materials used in supercritical water environments are determined by several environment- and material-dependent factors. In particular, irradiation-induced changes in microstructure and microchemistry are major concerns in a nuclear reactor. Many structural materials including alloys and ceramics have been proposed for use as SCWR components or materials for applying protective coatings in SCWRs. In this paper, the present status of supercritical fuel assembly design at home and abroad is reported. According to the special requirements of supercritical core design, a kind of configuration design of fuel assembly with two-flow core and using SiC as cladding material are proposed. The analysis results have shown that the design basically meets the requirements of fuel assembly design, which has good feasibility and performance. Copyright © 2015 by ASME.

关键词： Silicon carbide

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Preliminary analysis of FCM fuel thermal-mechanical performance under normal and transient conditions

Preliminary analysis of FCM fuel thermal-mechanical performa...

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Top Fuel 2016: LWR Fuels with Enhanced Safety and Performance

作者： Li, Wenjie Tang, Changbing Liu, Zhenhai Li, Wei Chen, Ping Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Design Sub-institute Nuclear Power Institute of China Chengdu610213 China

ISBN: (纸本)9780894487309

FCM fuel is a candidate fuel form to replace commercial UO2 fuel rod in LWR to enhance fuel reliability under accident conditions. The FCM pellet consists of TRISO particles embedded inside the dense SiC matrix. This fuel design is more complex than conventional LWR fuel, which needs new fuel performance models or analysis tools to assist fuel design and concept evaluation. In this paper an attempt was made to develop a finite element method to analyze FCM fuel pellet thermal-mechanical performance. Three idealized cases of normal operation, power ramp, and LOCA were analyzed. The results showed that the temperature distribution and stress distribution of FCM pellet exhibited a strong non-uniformity. The irradiation strain and creep of buffer layer and PyC layers had a strong effect on the mechanical performance of FCM pellet. The hoop stresses of SiC layers and SiC matrix increased significantly during the LOCA and varied with radial positions.

关键词： Finite element method

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Preliminary analysis of core heat-up for ATFs under accident conditions

Preliminary analysis of core heat-up for ATFs under accident...

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Top Fuel 2016: LWR Fuels with Enhanced Safety and Performance

作者： Li, Wei Chen, Ping Su, Guanghui Qiu, Suizheng Tian, Wenxi Li, Wenjie School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an Shaanxi710049 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu Sichuan610213 China

ISBN: (纸本)9780894487309

Experience gained in decades of nuclear safety research and previous nuclear accidents direct to the investigation of passive safety system design and accident-tolerant fuel (ATF) system which is now becoming a hot research point in the nuclear energy field. The ATF system is aim at upgrading safety characteristics of the nuclear fuel and cladding in a reactor core where active cooling has been lost, and is preferable or comparable to the conventional UO2-Zr fuel system when the reactor is in normal operation. By virtue of advanced materials with improved basic properties and oxidation resistance, the ATF system is placed high hopes on slowing down the accident progression, allowing wider margin of time for the mitigation measures to be effective. SiC and FeCrAl accident-tolerant claddings and FCM accident-tolerant fuel are considered in this work, as they are receiving more and more attention in China. In this paper, the improved performance of UO2-SiC, UO2-FeCrAl, FCM-SiC and FCM-FeCrAl fuel systems on the core heat-up progress in a pressurized water reactor (PWR) is analyzed by using the best-estimate system code RELAP5 and severe accident analysis program respectively. For this purpose two accident scenarios are selected, e.g., a large break LOCA as a design base accident and an extended station blackout (SBO) severe accident, to reflect the accident-tolerance characteristic of ATFs. Obtained quantitative results show promising safety enhancement in terms of peak cladding temperature (PCT) and recovery of the core coolability for the selected ATF systems, which is beneficial for further down-selections of various kinds of ATF systems.

关键词： Silicon carbide

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Research on Rotational Accuracy of Cylindrical Roller Bearings

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Procedia CIRP 2017年 62卷 380-385页

作者： Yu Yongjian Chen Guoding Li Jishun Xue Yujun School of Mechanical Engineering Northwestern Polytechnical University Xi’an 710072 China Henan Key Laboratory for Machinery Design and Transmission System Luoyang 471003 China School of Mechanical Engineering Henan University of Science and Technology Luoyang 471003 China

To investigate transferring mechanism of form error of bearing elements and rotational accuracy in cylindrical roller bearings, according to the bearing components motion and geometric relationships, a prediction model for rotational accuracy of cylindrical roller bearings based on roundness error of the inner raceway is presented. The effects of roundness error (i.e., amplitude, order) in the inner raceway, the number of rollers and radial clearance on the radial runout of inner ring are analyzed. Analytic solutions of the radial runout of inner ring are deduced when shapes of bearing elements are an ideal circle, which verifies the correctness of the presented model. The results show that the proposed model has better precision accuracy.

关键词： Cylindrical roller bearing Rotational accuracy Radial runout Roundness error Form error

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Forecast for Radial Runout of Outer Ring in Cylindrical Roller Bearing

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Procedia CIRP 2017年 62卷 375-379页

作者： Li Jishun Yu Yongjian Xue Yujun Henan Key Laboratory for Machinery Design and Transmission System Luoyang 471003 China School of Mechanical Engineering Henan University of Science and Technology Luoyang 471003 China School of Mechanical Engineering Northwestern Polytechnical University Xi’an 710072 China

The radial runout of outer ringin cylindrical roller bearing is investigated by numerical computation. Considering form error of outer raceway, a forecasting model for the radial runout of outer ring in cylindrical roller bearing is developed to study the influences of roundness error (i.e., amplitude, order) of outer raceway, number of rollers and radial clearance on the radial runout of outer ring. To testify the presented forecasting method, an analysis algorithm for computing the radial runout of outer ring with outer raceway shape of ellipse is derived. The comparison of the prediction results with the analytical results shows that the presented forecasting method has the better forecast precision.

关键词： Cylindrical roller bearing Radial runout of outer ring Roundness error Forecast

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On the lift force modeling for single bubble in water 3

On the lift force modeling for single bubble in water

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3rd International Topical Meeting on Advances in Thermal Hydraulics 2016, ATH 2016

作者： Li, Zhongchun Song, Xiaoming Jiang, Shengyao Ishii, Mamoru Science and Technology on Reactor System Design Technology Laboratory Chengdu610041 China Nuclear Power Institute of China Chengdu610041 China Tsinghua University Beijing100084 China Department of Nuclear Engineering Purdue University 47906 United States

ISBN: (纸本)9780894487330

Lift force is one of the interfacial momentum transfer terms in the framework of two-fluid modeling. It is vital for accurate understanding of two phase flow system. The present study concluded the lift force modeling and correlations proposed using analytical, experimental and numerical approaches. The correlations were assessed with the existing experimental and numerical simulation results. The regions where insufficient data and contradictions between modeling and experimental data were presented were identified. A strategy for the lift force modeling was proposed based on the similarity between drag force and lift force. In addition, the effects of bubble size, fluid properties, contamination and shear flow rate were discussed. © 2016, American Nuclear Society. All rights reserved.

关键词： Shear flow

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RANS simulation of natural convection in an enclosure with curved surface heating from below 3

RANS simulation of natural convection in an enclosure with c...

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3rd International Topical Meeting on Advances in Thermal Hydraulics 2016, ATH 2016

作者： Chai, Xiang Chen, Bin Xu, Cheng School of Nuclear Science and Engineering Shanghai Jiao Tong University 800 Dongchuan RD. Minhang District Shanghai China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China Karlsruhe Institute of Technology Kaiserstr. 12 Karlsruhe76131 Germany

ISBN: (纸本)9780894487330

Prediction accuracy of natural convection is strongly dependent on the choice of turbulence model. In this paper, different turbulence models as well as turbulent heat flux models are employed to predict the natural convection in an enclosure with curved surface heating from below and investigate their performance. Based on the simulation results, it is found that k-Ε model which is well known to overestimate the production of kinetic energy provides a higher prediction of Nusselt number while k-Ε-ζ-f model provides a relatively smaller estimation. A systematic CFD simulation is carried out for Rayleigh numbers in the range 109 to 1011, with which the influence from aspect ratio is also investigated. The effect of Rayleigh number on heat transfer is found to be significant and the dependency of Nusselt number (Nu) is obtained as a function of Rayleigh number (Ra). The influence from the aspect ratio of the simulation domain is found to be dependent on the choice of turbulence model. For k-Ε model, Nu increases as aspect ratio increases, while an opposite dependency is observed when k-Ε-ζ-f model is used. For this discrepancy, arguments are provided based on the streamlines and the profiles of Nu over the heating surface. © 2016, American Nuclear Society. All rights reserved.

关键词： Natural convection

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Influence of Sn addition on mechanical properties of gas tungsten arc welded AM60 Mg alloy sheets

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Transactions of Nonferrous Metals Society of China 2016年第8期26卷 2051-2057页

作者： Jun GOU Ai-tao TANG Fu-sheng PAN Jia SHE Su-qin LUO Jun-hua YE Da-wei SHI College of Materials Science and Engineering Chongqing University Chongqing 400044 China National Engineering Research Center for Magnesium Alloys Chongqing University Chongqing 400044 China Chongqing Academy of Science and Technology Chongqing 401123 China Science and Technology on Reactor System Design Technology Laboratory College of Materials Science and Engineering Guilin University of Technology Guilin 541004 China

The effects of Sn addition on the microstructure and mechanical properties of gas tungsten arc butt-welded Mg?6Al?0.3Mn (AM60) (mass fraction, %) alloy sheets were investigated by optical microscopy, scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and microhardness and tensile tests. The results indicate that both the average microhardness and joint efficiency of AM60 are improved by the addition of 1% Sn (mass fraction). The ultimate tensile strength of Mg?6Al?1Sn?0.3Mn (ATM610) reaches up to 96.8% of that of base material. Moreover, fracture occurs in the fusion zone ofATM610 instead of in the heat-affected zone of AM60 welded joint. The improvement in the properties is mainly attributed to the formation of Mg2Sn, which effectively obstructs the grain coarsening in the heat-affected zone, resulting in a relatively finemicrostructure. The addition of 1% Sn improves the mechanical properties of AM60 welded joint

关键词： AM60 Mg alloy ATM610 Mg alloy gas tungsten arc welding mechanical properties

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Mechanism study and theoretical simulation on heat split phenomenon in dual-cooled annular fuel element

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Annals of Nuclear Energy 2016年 94卷 44-54页

作者： Yangbin Deng Yingwei Wu Yuanming Li Dalin Zhang Wenxi Tian G.H. Su Suizheng Qiu State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an City 710049 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu 610213 China

In this study, the mechanisms that cause heat split, a specific phenomenon in dual-cooled annular fuel elements, were investigated. On the basis of thermal resistance analysis, the developing process of heat split phenomenon was summarized. It was found that thermal expansion, fuel densification, swelling, creep, relocation and fission gas release are the original parameters driving the development of heat split. Due to these factors, thermal resistances for heat flux to internal and external channels change with the operating time, which results in heat split. Furthermore, the theoretical simulation on heat split was performed by FROBA-ANNULAR, which is a coupled thermal–mechanical analysis code for dual-cooled annular fuel elements. key parameters at different burnup stages, including gap size, gap conductance, temperature profile, coolant flux and heat flux were obtained. The calculation result shows that the fraction of heat flux to the internal cooling channel experiences complicated variation at the range of 32.9–39.7%. In addition, it was found that heat split does not match with the coolant split, especially at the lower burnup stage. Asymmetric heat transfer occurred because of the imbalance between heat split and coolant split, resulting in a substantial asymmetric temperature profile. Furthermore, heat split exerts an influence on DBNRs of inner and outer channels, although the computational values were still within the allowable limits.

关键词： Dual-cooled annular fuel Heat split FROBA-ANNULAR code MDNBR

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