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Insights into Dissolved Oxygen Dependent Crack Initiation Mechanism of 316ln Stainless Steel Fatigue Tested in High-Temperature Pressurized Water

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SSRN 2024年

作者： Qiao, Yufei Li, Hui Tan, Jibo Liu, Daoping Zhang, Ziyu Wu, Xinqiang Ke, Wei CAS Key Laboratory of Nuclear Materials and Safety Assessment Liaoning Key Laboratory for Safety and Assessment Technique of Nuclear Materials Institute of Metal Research Chinese Academy of Sciences Shenyang110016 China School of Materials Science and Engineering University of Science and Technology of China Hefei230026 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China China

The corrosion fatigue behavior of 316LN SS hollow specimen was investigated in high-temperature pressurized water at different dissolved oxygen (DO) concentrations ( © 2024, The Authors. All rights reserved.

关键词： Corrosion fatigue

Surrogate representation of sink strengths and the long-term role of crystalline interfaces in the development of irradiation-induced bubbles

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arXiv

arXiv 2020年

作者： Luo, Jing Xin, Yong Zhou, Zhengcheng Zhu, Yichao Guo, Xu Department of Engineering Mechanics Dalian University of Technology Dalian116023 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology China International Research Center for Computational Mechanics Dalian University of Technology China

The present article addresses an early-stage attempt on replacing the analyticity-based sink strength terms in rate equations by surrogate models of machine learning representation. Here we emphasise, in the context of multiscale modelling, a combinative use of machine learning with scale analysis, through which a set of fine-resolution problems of partial differential equations describing the (quasi-steady) short-range individual sink behaviour can be asymptotically sorted out from the mean-field kinetics. Hence the training of machine learning is restrictively oriented, that is, to express the local and already identified, but analytically unavailable nonlinear functional relationships between the sink strengths and other local continuum field quantities. With the trained models, one is enabled to quantitatively investigate the biased effect shown by a void/bubble being a point defect sink, and the results are compared with existing ones over well-studied scenarios. Moreover, the faster diffusive mechanisms on crystalline interfaces are distinguishingly modelled by locally planar rate equations, and their linkages with rate equations for bulk diffusion are formulated through derivative jumps of point defect concentrations across the interfaces. Thus the distinctive role of crystalline interfaces as partial sinks and quick diffusive channels can be investigated. Methodologicalwise, the present treatment is also applicable for studying more complicated situation of long-term sink behaviour observed in irradiated materials. Copyright © 2020, The Authors. All rights reserved.

关键词： Machine learning

Enhancing Mechanical Properties and Microstructure Evolution of Hybrid Az61-5sic-0.5cnts Composite During Equal Channel Angular Pressing

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SSRN 2024年

作者： Zhou, Mingyang Zhao, Yanli Sun, Dan Long, Ziyao Gen, Laiyao Fan, Lingling Gao, Shixin Xin, Yong Quan, Gaofeng Gupta, Manoj Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China School of Mechanical Engineering Chengdu University Chengdu Sichuan610106 China School of Materials Science and Engineering Southwest Jiaotong University Chengdu610031 China 9 Engineering Drive 1 Singapore117576 Singapore

Equal channel angular pressing (ECAP) is one of widely used severe plastic deformation methods for improving performance of metallic materials. In this work, the effects of the ECAP on the microstructural evolution and mechanical properties of the AZ61-5SiC-0.5CNTs composite were studied systematically. The results revealed that ECAP can effectively reduce the porosity of the AZ61-5SiC-0.5CNTs composite, refine grains, weaken basal texture, and promote the further dispersion of CNTs, which can optimize the microstructure of the composite. However, the large shear effect of ECAP also leads to the destruction of the structural integrity of the CNTs and thus reduces the strengthening effect. Due to the combined effects of grain refinement, porosity changes, texture evolution, and structural damage of CNTs, the composites reached the highest strength after 2 ECAP passes at 250 °C. The yield and tensile strengths were increased to 383 MPa (+11.0%) and 445 MPa (+8.0%), respectively, while the elongation was marginally reduced, but remained around 6%. © 2024, The Authors. All rights reserved.

关键词： Equal channel angular pressing

Predicting Reverse Flow Characteristics in Equal-Height-Difference Passive Heat Removal system for Ocean Nuclear Power

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SSRN 2022年

作者： Wang, Zhiwei He, Yanping Duan, Zhongdi Huang, Chao Li, Mingzhi Liu, Shiwen Hao, Chengming State Key Laboratory of Ocean Engineering Shanghai Jiao Tong University Shanghai200240 China Institute of Marine Equipment Shanghai Jiao Tong University Shanghai200240 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

The equal-height-difference passive heat removal system (EHDPHRS) via natural circulation driving and utilizes ocean as infinite heat sink for heat dissipation, showing broad application prospect in ocean nuclear power field;but the heat removal pipe normally encounters the reverse flow of the cold seawater into the pipe, leading to operation instability and even condensation-induced water hammer. In this study, the integration of the volume of fluid model and the condensation model based on surface renewal theory is used to simulate the reverse flow characteristics in heat removal pipe under single-and two-phase natural circulation conditions. The interfacial heat and mass transfer are calculated by user-defined functions. The numerical results reveal that the buoyancy force ( [[EQUATION]] ) and condensation driving force ( [[EQUATION]] ) both accelerate the reverse flow, while the inertial force ( [[EQUATION]] ) restrains the reverse flow;the reverse flow length presents monotonous decrease with increasing flow velocity under single-phase conditions and parabolic-like trend for two-phase flow. A prediction correlation for reverse length is developed using dimensionless Reynolds number, Grashof number and vapor volume fraction, covering single- and two-phase conditions. The predicted reverse length by the correlation agrees with 94% of the results within deviations of [[EQUATION]] 15%. © 2022, The Authors. All rights reserved.

关键词： Forecasting

Experimental Study on Droplet Behavior and Mechanisms During Reflooding in a Single-Rod Channel

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SSRN 2022年

作者： Chen, Mingjing Liu, Hanzhou Chen, Deqi Zhong, Lei Liu, Haidong Yu, Hongxing Yu, Ruan Feng, Peng Key Laboratory of Low-grade Energy Utilization Technologies and Systems Chongqing University Ministry of Education Chongqing 400044 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China Key Laboratory of Aerospace Thermophysics Ministry of Industry and Information Technology School of Energy Science and Engineering Harbin Institute of Technology Harbin150001 China

Discrete droplets have received extensive attention in reflooding processes under Loss Of Coolant Accident (LOCA) conditions due to their large vapor-liquid interface area, droplet collision, droplet evaporation, and other behaviors that have a significant impact on the heat transfer of Dispersed Flow Film Boiling (DFFB). Unfortunately, the accurate prediction of the characteristics of droplet velocity and distribution under DFFB cannot be achieved at present, due to the lack of sufficient visual data support. For this reason, a visualization experiment of high-temperature surface reflooding in a single-rod channel was carried out. In this paper, the effect of the thermal parameter, such as input heat flux on the transient droplet behavior, which include the droplet size and velocity, has been analaysed in detail. Furthermore, to provide physical support for building droplet distribution models containing more physical mechanisms in the future, several droplet formation and breakup mechanisms, which include the Helmholtz instability, capillary breakage and rewetting area sputter, has been discussed in this paper. © 2022, The Authors. All rights reserved.

关键词： Drop breakup

BDGSE: A Symbolic Execution Technique for High MC/DC

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BDGSE: A Symbolic Execution Technique for High MC/DC

IEEE International Conference on Software Quality, Reliability and Security (QRS)

作者： Huangli Cai Zhiyi Zhang Yifan Jian Dan Li Zhiqiu Huang Collage of Computer Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing China Collaborative Innovation Center of Novel Software Technology and Industrialization Nanjing China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China Ministry Key Laboratory for Safety-Critical Software Development and Verification Nanjing University of Aeronautics and Astronautics Nanjing China

Modified Condition/Decision Coverage (MC/DC) is a test coverage standard with excellent fault detection capability, which is widely used in testing safety-critical software. Symbolic execution generates test cases automatically to achieve high code coverage. However, since symbolic execution uses short-circuit evaluation to evaluate decisions, it fails to guarantee the consistency of other conditions in a decision required by the MC/DC criterion. As a result, it is incapable of generating MC/DC test cases to test safety-critical systems adequately. To solve this problem, we propose Branch Dependence Guided Symbolic Execution (BDGSE), a symbolic execution technique for high MC/DC. The approach utilizes static analysis to compute the branch dependencies, then guides symbolic execution to selectively explore paths and simplify test cases, and finally generates a small number of test cases to achieve high MC/DC coverage. Our experimental results show that BDGSE can generate high-quality test cases. Although BDGSE generates fewer test cases, it can achieve higher MC/DC coverage than SPF and random methods, and the fault detection capability of test cases generated by BDGSE is comparable to that of test cases generated by SPF.

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High-Fidelity Neutronic/Thermal-Hydraulic Coupling Analysis of Plate-Type reactor based on MOOSE and cosRMC

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SSRN 2023年

作者： Chen, Junyi Liu, Guodong Huang, Shanfang He, Ying Qiu, Meiming Wang, Kan Lu, Chuan Li, Zhigang Quan, Guoping Wang, Xing Department of Engineering Physics Tsinghua University Haidian district Beijing100084 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Shuangliu district Chengdu610213 China State Power Investment Corporation Research Institute Changping district Beijing102209 China

A full scale high-fidelity neutronic/thermal-hydraulic coupled analysis method for plate-type reactor is proposed based on the open-source Multiphysics Object-Oriented Simulation Environment (MOOSE) and Monte Carlo Code cosRMC. The two-dimensional heat transfer model and one-dimensional coolant subchannel model are established, and integrated into the thermalhydraulic analysis code SPhase. The code-to-code validations of SPhase show good agreement with that of CTF and Fluent. The detailed neutronics model and parameters schemes are verified through cosRMC to ensure accuracy of physics calculation. The criticality search is implented, and the full scale JRR-3M critical coupled simulation under steady state is realized through celllevel resolution. The thermal feedback introduces negative activity of about 400 pcm. The insertion of absorbers renders the complexity of power distribution. The reflection effect results in peak thermal neutrons flux and temperature at the edge of the core. This work provides reference for correlational studies on neutronic/thermal-hydraulic characteristics of plate-type reactor. © 2023, The Authors. All rights reserved.

关键词： Multiphysics

Application of feedforward predictive control in DC furnace coordination system

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Journal of Physics: Conference Series 2021年第1期1780卷

作者： Zhiguang DENG HE Zhengxi ZHU Biwei ZHU Jialiang LV Xin WU Qian National Key Labortory of Science and Technology on Reactor System Design Technology Chengdu610213China

In order to solve the control difficulties such as large dynamic delay, serious coupling between machine and furnace and strong nonlinear, the feedforward and feedback predictive control is proposed to control the coordinated system on the basis of multi-model predictive control, and the static feedforward part designs the feed line feedforward of coal quantity against coal quality disturbance on the basis of the accurate balance of energy. Thus, the reference total fuel quantity under the target load instruction is determined, and the dynamic part fully considers the dynamic compensation of the unit energy storage, gives a certain overshoot fuel quantity to the boiler regulation, speeds up its response, and ensures the rapidity of the unit. The real-time simulation results of virtual DPU (Distributed Processing Unit) show that the designed feedforward-feedback predictive control can quickly respond to load change, improve the resistance to fuel disturbance, reduce the fluctuation of main steam pressure, and better ensure the safe, economic and stable operation of the coordination system.

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Assessment of Coupled Effect of Steam Pipes on Seismic Analysis of reactor Coolant system

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IOP Conference Series: Earth and Environmental science 2021年第4期719卷

作者： Lijuan Li Zhenyu Liu Hui Li Xianhui Ye Honglei Ai National Key Laboratory of Science and Technology on Reactor System Design Technology Chengdu Sichuan China

reactor coolant system is connected with auxiliary pipes, surge pipes and steam pipes. In order to facilitate the dynamic analysis of reactor coolant system, it is necessary to decouple the pipes connected with the reactor coolant system. Although some international standards stipulating requirements for the decoupling of subsystems from the main system, in order to further explore the influence of decoupling steam pipes, the seismic response of reactor coolant system with or without steam pipes is simulated by using ANSYS program. Firstly, the modal analysis of reactor coolant system is carried out to analysis the influence of steam pipes on the resonant frequency of reactor system. Then, the standardized seismic dynamic analysis of reactor system with or without steam pipes is carried out. The nozzle load (inlet and outlet nozzle load of main device, such as reactor pressure vessel, steam generator, pump) and support load (of main device such as reactor pressure vessel, steam generator, pump) are output and compared. According to nozzle load and support load, it can be seen that the steam pipes have little influence on the seismic analysis of reactor coolant system, i.e. steam pipes can be decoupled in the seismic analysis of reactor coolant system.

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