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学者姓名：卢凯
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When cracks are detected in structural components of nuclear power plants, the integrity of cracked components should be assessed by comparing the material strength with the crack driving force (e.g., stress intensity factor KI). To support the structural integrity assessment of nuclear components with cracks, several fitness-for-service (FFS) codes have been established in which KI solutions are provided for various components and cracks. For nozzle corner cracks in reactor pressure vessels (RPVs), the existing KI solutions are found to have limitations in applications because of the complexity of nozzle geometrical configurations and stress concentrations. In particular, only KI solutions at the deepest point of the nozzle corner crack are provided in the FFS codes and the applicable range of those KI solutions is not clear. Thus, in this study, three-dimensional finite element analyses (FEAs) were performed to develop normalized KI solutions for a wide range of nozzle corner cracks, with the objective of supporting the structural integrity assessment of RPV nozzles. The RPV inner radius to thickness ratio Rv/tv from 5 to 20, nozzle inner radius to thickness ratio Rn/tn from 1 to 5, and the nozzle inner radius to RPV inner radius ratio Rn/Rv from 0.025 to 0.25, were considered in the FEAs. The KI solutions along the crack root front of nozzle corner cracks with the normalized crack depth a/te from 0.1 to 0.6 (herein, te = 2 & sdot;max(tv, tn)) were analyzed with a fourth-order polynomial stress distribution applied on the crack face. By using the developed KI solutions for nozzle corner cracks, several application examples considering internal pressure and thermal transient are also presented in this paper. The results demonstrate that the developed KI solutions are highly useful for the integrity assessment of cracked RPV nozzles under diverse loading conditions.
Keyword ：
Finite element analysis Finite element analysis Loss of coolant accident Loss of coolant accident Nozzle corner crack Nozzle corner crack Reactor pressure vessel Reactor pressure vessel Stress intensity factor Stress intensity factor
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| GB/T 7714 | Lu, Kai , Li, Xuesen , Wu, Ziqiang et al. Numerical investigation on stress intensity factor solutions of nozzle corner cracks in reactor pressure vessels [J]. | INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING , 2025 , 218 . |
| MLA | Lu, Kai et al. "Numerical investigation on stress intensity factor solutions of nozzle corner cracks in reactor pressure vessels" . | INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING 218 (2025) . |
| APA | Lu, Kai , Li, Xuesen , Wu, Ziqiang , Wang, Dong , Pan, Jun , Zhang, Tairui . Numerical investigation on stress intensity factor solutions of nozzle corner cracks in reactor pressure vessels . | INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING , 2025 , 218 . |
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The initial behavior of multi-principal element alloys (MPEAs) is crucial to understanding their deformation mechanism. However, its orientation dependence remains poorly understood. The initial plastic behavior of three typical crystal planes (100), (110) and (111) of FeNiCr MPEA was investigated by nanoindentation experiments, molecular dynamics (MD) simulations and density functional theory (DFT) calculations. Our novel findings reveal that the initial plastic behavior of FeNiCr MPEA is highly orientation-dependent. Specifically, the (111) plane has the highest initial yield load, and (110) plane exhibits the smallest width of displacement burst. This is related to the number of activated slip systems and the evolution behavior of dislocation structure under different crystal orientations. These differences would not lead to different incipient mechanisms and activation volumes. For the first time, MD simulations not only clarify that the dislocation nucleation load is the decisive factor for the initial yield load but also disclose that the incipient behavior of (111) orientation is more sensitive to the lattice distortion (LD). In addition, DFT results unravel that intrinsic LD promotes dislocation nucleation by triggering heterogeneous distribution of charge density. Finally, the orientation dependence of incipient behavior in FCC FeNiCr MPEA shares similarities with conventional metals and other FCC MPEAs, but differs from BCC MPEAs due to their distinct slip systems. The key findings of this paper deepen our understanding of the incipient behavior of MPEAs.
Keyword ：
Crystal orientation Crystal orientation Incipient behavior Incipient behavior Lattice distortion Lattice distortion Molecular dynamics simulations Molecular dynamics simulations Multi-principal element alloys Multi-principal element alloys Nanoindentation Nanoindentation
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| GB/T 7714 | Zhang, X. K. , Fan, J. T. , Xiang, H. L. et al. Unveiling the critical role of crystal orientation in the incipient behavior of FCC FeNiCr multi-principal element alloy [J]. | INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES , 2025 , 297 . |
| MLA | Zhang, X. K. et al. "Unveiling the critical role of crystal orientation in the incipient behavior of FCC FeNiCr multi-principal element alloy" . | INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES 297 (2025) . |
| APA | Zhang, X. K. , Fan, J. T. , Xiang, H. L. , Yan, J. , Li, W. P. , Zhao, W. et al. Unveiling the critical role of crystal orientation in the incipient behavior of FCC FeNiCr multi-principal element alloy . | INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES , 2025 , 297 . |
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In our previous studies of Cr-coated Zr alloy cladding, models for the oxidation and degradation of Cr coating and for the oxidation and phase transformation of Zr alloy have been established. On these foundations, oxygen flux models for Cr-Zr non-eutectic and eutectic conditions are developed in this paper, enabling a comprehensive simulation of the oxidation processes of Cr-coated Zr alloy. The models are validated through oxidation experiments under isothermal and temperature ramp conditions, showing good agreement with the experimental data. The models can effectively simulate the processes where, under non-eutectic conditions, oxygen atoms first dissolve into the prior beta-Zr matrix after coating degradation, followed by the formation of alpha-Zr(O) and eventually ZrO2. For conditions with eutectic reaction, model assumption of immediate complete coating failure could lead to overestimation of substrate oxidation extent at low heating rates. This prediction deviation decreases as heating rate increases.
Keyword ：
Cr-coated Zr alloy Cr-coated Zr alloy Diffusion Diffusion High-temperature oxidation High-temperature oxidation Model development Model development Oxygen flux Oxygen flux
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| GB/T 7714 | Wang, Dong , Wu, Shihao , Lu, Kai et al. High-temperature oxidation of accident tolerant Cr-coated Zr alloy cladding: Model development and validation [J]. | JOURNAL OF NUCLEAR MATERIALS , 2025 , 606 . |
| MLA | Wang, Dong et al. "High-temperature oxidation of accident tolerant Cr-coated Zr alloy cladding: Model development and validation" . | JOURNAL OF NUCLEAR MATERIALS 606 (2025) . |
| APA | Wang, Dong , Wu, Shihao , Lu, Kai , Zhang, Yapei , Su, G. H. , Liu, Xi . High-temperature oxidation of accident tolerant Cr-coated Zr alloy cladding: Model development and validation . | JOURNAL OF NUCLEAR MATERIALS , 2025 , 606 . |
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This study focuses on waste heat recovery, renewable energy storage, and cascade energy utilization by proposing a polygeneration system that integrates a Carnot battery, an absorption refrigeration cycle, and multi-stage flash desalination. This system is engineered to provide cooling, heating, electricity, and freshwater. It utilizes a dual-pressure condensation heat pump to facilitate energy output across different stages, with the low-temperature condenser connected to the absorption refrigeration cycle, while one side of the high-temperature condenser acts as thermal energy storage. The provision of freshwater and domestic hot water primarily relies on excess heat from the absorption refrigeration cycle. In this research, the optimal working fluid for the Carnot battery was identified. Subsequently, the study analyzed the impact of several operating parameters on the system's thermodynamic performance and economy, including the outlet water temperature of the low-temperature condenser, the degree of superheat of the working fluid in the heat pump evaporator, the temperature of the storage tank, the isentropic efficiency of the compressor, and the mass flow rate ratio of the working fluid in the low/high-temperature condensers. Among them, the mass flow rate ratio of the working fluid in the low/high-temperature condensers has the most significant impact on the system, and the overall energy efficiency and payback period of the system increase by 138.51 % and 174.58 %, respectively. A multi-objective optimization of the system was performed using the Non-dominated Sorting Genetic Algorithm II to identify the optimal design parameters for the integrated generation system. The optimized system achieved total energy efficiency, exergy efficiency, and payback period of 23.26 %, 12.56 %, and 4.96 years, respectively. © 2025 Elsevier Ltd
Keyword ：
Absorption cooling Absorption cooling Absorption refrigeration Absorption refrigeration Carnot cycle Carnot cycle Condensers (liquefiers) Condensers (liquefiers) Economic analysis Economic analysis Electric energy storage Electric energy storage Energy efficiency Energy efficiency Energy utilization Energy utilization Exergy Exergy Fluids Fluids Genetic algorithms Genetic algorithms Heat storage Heat storage Hot working Hot working Multiobjective optimization Multiobjective optimization Renewable energy Renewable energy Thermal energy Thermal energy Thermal management (electronics) Thermal management (electronics) Waste heat Waste heat Waste heat utilization Waste heat utilization Water Water
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| GB/T 7714 | Liu, Xi , Lu, Pengxu , Wang, Dong et al. Energy-exergy-economic (3E) analysis and multi-objective optimization of a polygeneration system for cooling, heating, electricity, and freshwater based on carnot battery energy storage [J]. | Applied Thermal Engineering , 2025 , 279 . |
| MLA | Liu, Xi et al. "Energy-exergy-economic (3E) analysis and multi-objective optimization of a polygeneration system for cooling, heating, electricity, and freshwater based on carnot battery energy storage" . | Applied Thermal Engineering 279 (2025) . |
| APA | Liu, Xi , Lu, Pengxu , Wang, Dong , Liu, Zicheng , Lu, Kai . Energy-exergy-economic (3E) analysis and multi-objective optimization of a polygeneration system for cooling, heating, electricity, and freshwater based on carnot battery energy storage . | Applied Thermal Engineering , 2025 , 279 . |
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The temperature-dependent mechanisms for hydrogen-induced embrittlement and electrochemical corrosion in Ni-based superalloy 600 have been unravelled by means of tensile tests and potentiodynamic polarization tests under electrochemical environment. Increasing temperature accelerates electrochemical corrosion behaviour and induces the transition into intergranular corrosion, whereas there exists critical temperature THE, max, in which hydrogen-induced ductility loss reaches its peak. Detailed electron microscopy and thermal desorption spectroscopy analysis demystify that intergranular brittle fracture at THE, max is predominantly driven by hydrogen-dislocation-grain boundary interactions, compounded by high diffusible hydrogen content. These findings offer new insights into the critical role of temperature in modulating hydrogen embrittlement and corrosion, contributing to the design of materials in hydrogen environment.
Keyword ：
Hydrogen-dislocation-grain boundary Hydrogen-dislocation-grain boundary Hydrogen-induced brittle fracture Hydrogen-induced brittle fracture interaction interaction Intergranular corrosion Intergranular corrosion Ni-based superalloy Ni-based superalloy Temperature threshold Temperature threshold
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| GB/T 7714 | Li, Jiaqing , Yu, Xi , Zheng, Zhiye et al. Temperature-driven mechanisms of hydrogen embrittlement and electrochemical corrosion in Ni-based superalloy 600 [J]. | JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T , 2025 , 35 : 6715-6727 . |
| MLA | Li, Jiaqing et al. "Temperature-driven mechanisms of hydrogen embrittlement and electrochemical corrosion in Ni-based superalloy 600" . | JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T 35 (2025) : 6715-6727 . |
| APA | Li, Jiaqing , Yu, Xi , Zheng, Zhiye , Lu, Kai , Teng, Lin , Ding, Yu et al. Temperature-driven mechanisms of hydrogen embrittlement and electrochemical corrosion in Ni-based superalloy 600 . | JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T , 2025 , 35 , 6715-6727 . |
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This study provides investigations on whether the fracture toughness can be accurately predicted from mini-sized uniaxial tensile specimens with existing global and local approaches. The critical toughness model, based on classical fracture mechanics, and the energy release rate (ERR) model, based on damage mechanics, were used as the two representative global approaches. While the finite element simulated compact tension (CT) specimen implemented with Gurson-Tvergaard-Needleman model was used as the local approach. Specimen size effect was judged through the viewpoints of stress-strain relationship and damage development. It was proved that the specimen size has no significant influence on stress-strain relationship, and has little influence on damage developments when the thickness reaches 1.0 mm. Fracture toughness predictions were conducted on four metals, including two steels (SA508Gr.3Cl.1 and 18MnMoNbR), one aluminum alloy (6061-T651), and one titanium alloy (TC4). For TC4 exhibiting brittle cleavage features on the fracture surface of CT specimens, neither the global nor the local approach can accurately predict its fracture toughness. For 6061-T651 exhibiting both ductile and brittle features on the fracture surface of CT specimens, there exists significant macroscopic crack propagation at the moment of conventional fracture toughness determination. The existence of significant macroscopic crack is inconsistent with the "equivalent crack" assumption in the ERR model, leading to a failure in its fracture toughness prediction. For two steels following the "equivalent crack" assumption, the ERR model and the local approach yield more accurate predictions (with the maximum error around 10 %) than their critical toughness counterpart (with the maximum error around 30 %).
Keyword ：
Critical toughness model Critical toughness model Energy release rate model Energy release rate model Fracture toughness Fracture toughness Local approach Local approach Mini-sized uniaxial tensile specimen Mini-sized uniaxial tensile specimen
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| GB/T 7714 | Zhang, Tairui , Shang, Xiandong , Zhang, Naixin et al. An investigation on fracture toughness predictions from mini-sized uniaxial tensile specimens with global and local approaches [J]. | THEORETICAL AND APPLIED FRACTURE MECHANICS , 2024 , 131 . |
| MLA | Zhang, Tairui et al. "An investigation on fracture toughness predictions from mini-sized uniaxial tensile specimens with global and local approaches" . | THEORETICAL AND APPLIED FRACTURE MECHANICS 131 (2024) . |
| APA | Zhang, Tairui , Shang, Xiandong , Zhang, Naixin , Lu, Kai , Xie, Mingjiang . An investigation on fracture toughness predictions from mini-sized uniaxial tensile specimens with global and local approaches . | THEORETICAL AND APPLIED FRACTURE MECHANICS , 2024 , 131 . |
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In this paper, the cyclic elastic-plastic behaviors of the centrifugal steam compressor impeller (CSCI) structure under practical operating conditions are discussed employing the linear matching method (LMM). The three-stage strategy of the LMM is employed to determine the shakedown and ratchet boundaries by conducting a series of iterative direct steady cyclic analysis, and based on this, the load regions corresponding to different types of damage behavior that may occur during the operation are identified. Computational results reveal slight contraction in the structural response diagram when considering actual material constitutive relationships, compared to ideal elastic-plastic models. Meanwhile, by integrating the unified ratchet and fatigue program with fatigue experimental data, a series of constant low-cycle fatigue life curves has been presented for different service conditions. Furthermore, a comparison with detailed step-by-step inelastic analyses confirms the applicability and great efficiency of the LMM in practical engineering problems. The cyclic elastic-plastic behavior of impeller were investigated using the three-stage procedure. The effect of temperature-dependent and strain hardening on structural response of impeller were evaluated. The constant low-cycle life fatigue curves of the impeller structure were generated. The applicability and great efficiency of linear matching method have been confirmed.
Keyword ：
impeller impeller linear matching method linear matching method low cycle fatigue low cycle fatigue ratchet limit ratchet limit shakedown limit shakedown limit
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| GB/T 7714 | Li, Jianxun , Wang, Xiaoxiao , Ma, Zhiyuan et al. On the elastic-plastic behaviors of centrifugal steam compressor impeller under cyclic thermomechanical loading [J]. | FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES , 2024 , 47 (8) : 2888-2904 . |
| MLA | Li, Jianxun et al. "On the elastic-plastic behaviors of centrifugal steam compressor impeller under cyclic thermomechanical loading" . | FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES 47 . 8 (2024) : 2888-2904 . |
| APA | Li, Jianxun , Wang, Xiaoxiao , Ma, Zhiyuan , Lu, Kai , Chen, Haofeng , Wang, Weiqiang . On the elastic-plastic behaviors of centrifugal steam compressor impeller under cyclic thermomechanical loading . | FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES , 2024 , 47 (8) , 2888-2904 . |
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In this work, hydrogen diffusion behavior and mechanisms in the 4130X steel influenced by temperature, locally high concentration, and grain boundary were studied by leveraging both electrochemical hydrogen permeation experiments and molecular dynamics simulations. It was revealed that the hydrogen diffusion coefficient of the 4130X steel was increased with increasing temperature and decreasing locally high hydrogen concentration. The grain boundaries with misorientation below 15 degrees characterized by an electron backscatter diffraction map were identified as hydrogen trapping sites, thus rendering a lower mean square displacement of hydrogen atoms and localized hydrogen diffusion trajectories. Furthermore, at a high hydrogen concentration of 4 at. %, these grain boundaries were saturated by hydrogen atoms, and platelet-like hydrogen clusters were formed within the lattice, which further inhibited the diffusive motion of hydrogen atoms. These findings would deepen our understanding of hydrogen embrittlement mechanisms by establishing the connections between macroscopic permeation behavior and atomic-scale hydrogen diffusion in structural materials.
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| GB/T 7714 | Li, Jiaqing , Zheng, Zhiye , Yu, Xi et al. Hydrogen diffusion mechanisms in the 4130X steel: An integrated study with electrochemical experiments and molecular dynamics simulations [J]. | JOURNAL OF APPLIED PHYSICS , 2024 , 136 (16) . |
| MLA | Li, Jiaqing et al. "Hydrogen diffusion mechanisms in the 4130X steel: An integrated study with electrochemical experiments and molecular dynamics simulations" . | JOURNAL OF APPLIED PHYSICS 136 . 16 (2024) . |
| APA | Li, Jiaqing , Zheng, Zhiye , Yu, Xi , Lu, Kai , Liang, Huilong , Yin, Pengbo et al. Hydrogen diffusion mechanisms in the 4130X steel: An integrated study with electrochemical experiments and molecular dynamics simulations . | JOURNAL OF APPLIED PHYSICS , 2024 , 136 (16) . |
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The stress intensity factor (SIF) solutions for subsurface flaws in flat plates are provided in Appendix A of ASME Boiler and Pressure Vessel Code Section XI. A part of the SIF solutions was initially provided in the 2015 edition. The solutions were obtained for the fourth order polynomial stress distribution base on the influence function method. The solutions were expanded in the 2021 edition for subsurface flaws near the surface of the plate. The additional solutions were obtained based on the J-integral from the elastic finite element analyses. However, recent investigations have found that there is a minor discrepancy in trend between the two sets of SIF solutions because they were obtained by using different numerical methods. Although the discrepancy is very small, the change in trend causes some difficulties in engineering applications. In this work, the SIF solutions are recalculated using the same numerical method based on the J-integral from elastic finite element analyses. The results are compared with the solutions in the current Section XI, RSE-M, and are finally cross-checked with the results obtained from an independent numerical model. The results are useful to eliminate the discrepancy in trend in the SIF solutions for subsurface flaws in flat plates in the current edition of Section XI. Copyright © 2024 by ASME.
Keyword ：
Boiler codes Boiler codes Convergence of numerical methods Convergence of numerical methods Fracture mechanics Fracture mechanics Pressure vessel codes Pressure vessel codes Pressure vessels Pressure vessels Stress analysis Stress analysis Stress concentration Stress concentration Stress intensity factors Stress intensity factors
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| GB/T 7714 | Li, Suo , Li, Yinsheng , Lu, Kai et al. ANALYSES OF STRESS INTENSITY FACTOR SOLUTIONS FOR SUBSURFACE FLAWS IN FLAT PLATES [C] . 2024 . |
| MLA | Li, Suo et al. "ANALYSES OF STRESS INTENSITY FACTOR SOLUTIONS FOR SUBSURFACE FLAWS IN FLAT PLATES" . (2024) . |
| APA | Li, Suo , Li, Yinsheng , Lu, Kai , Lacroix, Valéry , Dulieu, Pierre . ANALYSES OF STRESS INTENSITY FACTOR SOLUTIONS FOR SUBSURFACE FLAWS IN FLAT PLATES . (2024) . |
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In the structural integrity assessment of an embrittled reactor pressure vessel (RPV) based on probabilistic fracture mechanics (PFM), it is crucial to consider both of the mean value and the uncertainty of the embrittlement prediction. Typically, the embrittlement prediction uncertainty is given by a normal distribution, and its standard deviation is determined from the residuals of the measured and predicted values of all data used to develop the embrittlement prediction method. Therefore, the same uncertainty is assumed regardless of neutron fluence and the available data. To overcome this issue, the Japan Atomic Energy Agency recently developed the embrittlement prediction method based on machine learning and Bayesian statistics, i.e., the Bayesian nonparametric (BNP) method, and introduced it to the PFM analysis code. The BNP method can predict the probability distribution according to data scarcity and provide more reasonable uncertainty because it estimates significant uncertainties where the scatter of actual measured data is large and the number of data is small. In this study, PFM analysis for a Japanese model RPV in a pressurized water reactor is conducted using the PFM analysis of structural components in aging light water reactors, where the embrittlement probability distribution calculated using the BNP method is used. Furthermore, the effects of different embrittlement prediction methods and uncertainties on the failure frequency of RPVs are investigated in the PFM analyses, and the results are presented.
Keyword ：
Irradiation embrittlement Irradiation embrittlement Machine learning Machine learning Probabilistic fracture mechanics Probabilistic fracture mechanics Reactor pressure vessel Reactor pressure vessel
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| GB/T 7714 | Takamizawa, H. , Lu, K. , Li, Y. . Probabilistic fracture mechanics analyses of a reactor pressure vessel using the irradiation embrittlement evaluation based on the Bayesian nonparametric method [J]. | INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING , 2024 , 210 . |
| MLA | Takamizawa, H. et al. "Probabilistic fracture mechanics analyses of a reactor pressure vessel using the irradiation embrittlement evaluation based on the Bayesian nonparametric method" . | INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING 210 (2024) . |
| APA | Takamizawa, H. , Lu, K. , Li, Y. . Probabilistic fracture mechanics analyses of a reactor pressure vessel using the irradiation embrittlement evaluation based on the Bayesian nonparametric method . | INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING , 2024 , 210 . |
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