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arXiv 2024年

作者： Zhang, Heng He, Yun-Ling Liu, Dong Hang, Qin Yao, He-Min Xiang, Di Chongqing University of Posts and Telecommunications Chongqing400065 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China CNNC Engineering Research Center of Nuclear Energy Software and Digital Reactor Chengdu610213 China

The neutron diffusion equation plays a pivotal role in the analysis of nuclear reactors. Nevertheless, employing the Physics-Informed Neural Network (PINN) method for its solution entails certain limitations. Traditional PINN approaches often utilize fully connected network (FCN) architecture, which is susceptible to overfitting, training instability, and gradient vanishing issues as the network depth increases. These challenges result in accuracy bottlenecks in the solution. In response to these issues, the Residual-based Resample Physics-Informed Neural Network(R2-PINN) is proposed, which proposes an improved PINN architecture that replaces the FCN with a Convolutional Neural Network with a shortcut(S-CNN), incorporating skip connections to facilitate gradient propagation between network layers. Additionally, the incorporation of the Residual Adaptive Resampling (RAR) mechanism dynamically increases sampling points, enhancing the spatial representation capabilities and overall predictive accuracy of the model. The experimental results illustrate that our approach significantly improves the model’s convergence capability, achieving high-precision predictions of physical fields. In comparison to traditional FCN-based PINN methods, R2-PINN effectively overcomes the limitations inherent in current methods, providing more accurate and robust solutions for neutron diffusion equations. Copyright © 2024, The Authors. All rights reserved.

关键词： Network architecture

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Formally Verified a Front-End of the Trusted Code Generator for Safety I&C Software of NPPs 5th

Formally Verified a Front-End of the Trusted Code Generator ...

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5th International Symposium on Software Reliability, Industrial Safety, Cyber Security and Physical Protection of Nuclear Power Plant, ISNPP 2020

作者： Lan, Lin Ma, Quan Hou, Rong-Bin Jiang, Wei Liu, Ming-Xing Yang, Fei Li, Yong Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of the China Chengdu Sichuan China Harbin Engineering University Harbin China

ISBN: (纸本)9789811634550

In nuclear power plant embedded software control area, graphical control algorithms are described by Lustre program and designed with graphical editors of engineering station. After they are translated into C programs through a code generator, then the C programs are downloaded to the embedded platform software of NASPIC. The correctness of the code generator will directly determine the credibility and safety of NASPIC. Therefore, it’s important to ensure the correctness of the code generator translation process. Formally verified the correctness of a code generator, which has been studied for many years and becomes a most effective approach to develop a trusted code generator. This article is based on the requirements of nuclear safety-level I&C (Instrumentation & Control) system and mainly presents the development of a formally verified code generator front-end. The front-end translates Lustre source program into S_Lustre (a sequential intermediate language). And it is programmed and proved in Coq (Auxiliary Theorem Prover). During the development of the front-end, two key technical challenges have been resolved. The first is to ensure every id which appeared in the Lustre program has been defined. The second is to implement the casualty analysis and determine the evaluation order of user-defined types and equations based on the dependencies. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Formal verification

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Trusted Algorithm Compiler for Safety I&C Software of NPPs Based on Formal Methods 5th

Trusted Algorithm Compiler for Safety I&C Software of NPPs B...

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5th International Symposium on Software Reliability, Industrial Safety, Cyber Security and Physical Protection of Nuclear Power Plant, ISNPP 2020

作者： Yang, Fei Lan, Lin Ma, Quan Han, Wen-Xing Liu, Ming-Xing Jiang, Wei Science and Technology On Reactor System Design Technology Laboratory Nuclear Power Institute of the China Chengdu Sichuan China Harbin Engineering University Harbin China

ISBN: (纸本)9789811634550

The algorithm for the 1E system of NPPs is generally developed by a graph making tool at the engineering station. After the executable file is generated by the compiler and downloaded to the platform software, the credibility of the executable algorithm depends on the credibility of the generated programming code. Therefore, its security requirements put high demands on the compiler. The formal method has been developed rapidly in response to the problem of trusted compilation in recent years. This paper studies the main methodology and key technological components for designing and implementing the trusted compilers, meanwhile emphasize its industrial application based on existing research. The application is optimized, and a new composite compilation architecture is proposed, which reduces the difficulty of proof work and enhances the flexibility of the compiler’s later phase. Finally, several compiler optimization procedures for the security level software NASPIC are studied, and the algorithm compilation is enhanced, as well as the trusted performance of the device. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Formal verification

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Experimental Study on Flow Resistance and Phase Distribution of Gas-Liquid Flow in Helical Cruciform Fuel Assembly

SSRN

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SSRN 2024年

作者： Zhang, Qi Wang, Haoyu Li, Junlong Ren, Quanyao Zhou, Yi Zheng, LeLe Zhang, Yile Li, Dongyang Gu, Hanyang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China School of Nuclear Science and Engineering Shanghai Jiao Tong University Shanghai200240 China Harbin Engineering University China

The helical cruciform fuel (HCF) is characterized by self-supporting and enhanced transverse mixing, which may replace the cylindrical fuel of the light water reactor (LWR). In this work, the flow resistance and phase distribution of a 4×4 HCF assembly was investigated by experimental method. The experimental system of air-water two-phase flow was established, and the void fraction was gained by wire-mesh sensor (WMS). The dummy HCF elements produced by additive manufacturing technology were assembled with the locating plates. The evolution of the flow regime and the void fraction of the central and peripheral were paid particular attention. The correlations for the two-phase friction multiplier and void fraction were proposed based on the experimental data. © 2024, The Authors. All rights reserved.

关键词： Two phase flow

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An IGBT Device Health Status Assessment Method Considering the Influence of Operating Conditions

An IGBT Device Health Status Assessment Method Considering t...

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IEEE/IAS Industrial and Commercial Power system Asia (I&CPS Asia)

作者： Cheng Yang Zeyu Duan Ran Yao Hui Li Wei Lai Yuan Min Yannan Yuan Wenxing Han State Key Laboratory of Power Transmission Equipment & System Security and New Technology Chongqing University Chongqing China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China ChengDu China

The Insulated Gate Bipolar Transistor (IGBT) is a critical component of power electronic equipment, and its health is of utmost importance to ensure the reliability and stability of the entire system. This paper proposes a method for assessing the health status of IGBT device under various operating conditions. Firstly, a finite element model of the IGBT device is established to analyze the influence of solder layer void and bond line detachment on the saturation voltage of the device. Secondly, the device parameters are simulated under different working conditions, and an adaptive neural network algorithm is used to establish the IGBT equipment health state evaluation model. Finally, the results of the model are analyzed, and the prediction results under random conditions are compared with the simulation results. The results show that this method effectively evaluates the health status of IGBT devices.

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AN UNSUPERVISED LEARNING-BASED FRAMEWORK FOR EFFECTIVE REPRESENTATION EXTRACTION OF reactor ACCIDENTS

arXiv

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arXiv 2022年

作者： Li, Chengyuan Li, Meifu Qiu, Zhifang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu Sichuan China

Compared to knowledge-based diagnostic systems, data-based methods tend to perform better in terms of speed and accuracy in diagnosing reactor accidents, and have significant advantages in terms of scalability of models. With the increasing use of high-precision system analysis programs in nuclear engineering, the number of high-fidelity computational data for accident simulation is exploding. Therefore, an algorithm that can achieve both automatic extraction of low-dimensional features from the data and guarantee the validity of the features is needed to improve the performance and confidence of the accident diagnosis system. This study proposes an autoencoder-based autonomous learning framework, namely Padded Auto-Encoder (PAE), which is able to automatically encode accident monitoring data that has been noise-added and with partially missing data into low-dimensional feature vectors via a Vision Transformer-based encoder, and to decode the feature vectors into noise-free and complete reconstructed monitoring data. Thus, the encoder part of the framework is able to automatically infer valid representations from partially missing and noisy monitoring data that reflect the complete and noise-free original data, and the representation vectors can be used for downstream tasks for accident diagnosis or else. In this paper, LOCA of HPR1000 was used as the study object, and the PAE was trained by an unsupervised method using cases with different break locations and sizes as the dataset. The encoder part of the pre-trained PAE was subsequently used as the feature extractor for the monitoring data, and several basic statistical learning algorithms for predicting the break locations and sizes. The results of the study show that the pre-trained diagnostic model with two stages has a better performance in break location and size diagnostic capability with an improvement of 41.62% and 80.86% in the metrics respectively, compared to the diagnostic model with end-to-end model st

关键词： Extraction

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A Long-term Dependent and Trustworthy Approach to reactor Accident Prognosis based on Temporal Fusion Transformer

arXiv

引用

arXiv 2022年

作者： Li, Chengyuan Qiu, Zhifang Ma, Yugao Li, Meifu Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

Prognosis of the reactor accident is a crucial way to ensure appropriate strategies are adopted to avoid radioactive releases. However, there is very limited research in the field of nuclear industry. In this paper, we propose a method for accident prognosis based on the Temporal Fusion Transformer (TFT) model with multi-headed self-attention and gating mechanisms. The method utilizes multiple covariates to improve prediction accuracy on the one hand, and quantile regression methods for uncertainty assessment on the other. The method proposed in this paper is applied to the prognosis after loss of coolant accidents (LOCAs) in HPR1000 reactor. Extensive experimental results show that the method surpasses novel deep learning-based prediction methods in terms of prediction accuracy and confidence. Furthermore, the interference experiments with different signal-to-noise ratios and the ablation experiments for static covariates further illustrate that the robustness comes from the ability to extract the features of static and historical covariates. In summary, this work for the first time applies the novel composite deep learning model TFT to the prognosis of key parameters after a reactor accident, and makes a positive contribution to the establishment of a more intelligent and staff-light maintenance method for reactor systems. Copyright © 2022, The Authors. All rights reserved.

关键词： Nuclear industry

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Experimental Study on Turbulent Characteristics of Dispersed Bubbly Flow in a Narrow Rectangular Channel by Two-Phase Piv

SSRN

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SSRN 2023年

作者： Chen, Wuguang Huang, Guangyuan Hu, Yuanbiao Junlian, Yin Wang, Dezhong Li, Songwei Yang, Fan School of Nuclear Science and Engineering Shanghai Jiaotong University Shanghai200240 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China

Narrow rectangular channels are widely used in high heat flux applications, due to the high heat transfer efficiency and compact structure. However, a rare understanding was known about the two-phase turbulent characteristics. In this study, an experimental investigation of bubble and turbulent characteristics of dispersed bubbly flow in the narrow rectangular channel was carried out by using the high-speed camera and two-phase particle image velocimetry. The bubble size effect was studied independently using the continuous spectrum bubble generator. According to the results, the bubble size distribution conforms to a Weibull distribution, and the wall-peak void fraction distributions were found. Both turbulent enhancement and suppression were observed in current conditions. Large bubbles enhance turbulence intensity, while small bubbles suppress it. The eddy viscosity ratio [[EQUATION]] characterizes the modification of turbulence intensity by bubbles, with a critical value of [[EQUATION]]. © 2023, The Authors. All rights reserved.

关键词： High speed cameras

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Corrosion Behavior of Alumina-Forming Austenitic Steel in Supercritical Carbon Dioxide Conditions: Effects of Nb Content and Temperature

SSRN

引用

SSRN 2023年

作者： Ma, Zhaodandan Cong, Shuo Chen, Huan Liu, Zhu Dong, Yuanyuan Tang, Rui Chen, Yong Guo, Xianglong Science and Technology on Reactor System Design Technology Laboratory Chengdu610041 China Science and Technology on Reactor Fuel and Materials Laboratory Chengdu610041 China Nuclear Power Institute of China Chengdu610041 China Shanghai Jiao Tong University Shanghai200030 China

The corrosion behavior of alumina-forming austenitic (AFA) stainless steels with different Nb additions in supercritical carbon dioxide environment at 500℃, 600℃ and 20 MPa were investigated. A novel structure with a double oxide was identified as outer Cr2O3 oxide film and inner Al2O3 oxide scale with discontinuous Fe-Cr spinel outermost in the steels with low Nb content and a transitional layer, consisting of Cr spinel and γ`-Ni3Al phase was distributed randomly below the oxide scale. The oxidation resistance was improved by decreasing diffusion of oxygen after adding 0.6wt.% Nb. However, the corrosion resistance ability degraded significantly at higher Nb level due to the accelerated diffusion rate of ions through the refined grain boundaries, which resulted in the formation of a continuous thick outer FeCr2O4 layer on the surface and an internal oxide zone. Fe2(Mo, Nb) Laves phase were discovered as well with high Nb addition, which promoted the production of cracks inside the oxide film. Fewer spinel and thinner oxide scales were found after exposure at 500℃. The specific mechanism was discussed. © 2023, The Authors. All rights reserved.

关键词： Alumina

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Intra Fast Mode Decision Algorithm and Hardware design for AVS2

Intra Fast Mode Decision Algorithm and Hardware Design for A...

引用

2021 International Conference on Signal Processing and Machine Learning, CONF-SPML 2021

作者： Xie, Hao Liu, Kaiyang Zhao, Yang Zheng, Xiao Qing, Xianguo Nuclear Power Institute of China Science and Technology on Reactor System Design Technology Laboratory Chengdu China Peking University School of Software and Microelectronics Beijing China

ISBN: (纸本)9781665417341

AVS2 is a kind of video coding standard proposed by China, it adopts 33 intra prediction modes to improve coding performance, while the computational complexity has increased dramatically. In order to reduce the complexity of AVS2 intra mode decision and make the AVS2 hardware encoder meet real-time requirements, this paper proposes the AVS2 intra fast mode decision algorithm and hardware design. The experimental results show that the intra mode decision algorithm and hardware design proposed in this paper can meet the throughput requirement of 1920x1080@60fps at a clock frequency of 300MHz. By using Xilinx FPGA XC7K325T 900 on the Vivado HLS platform for synthesis, only 10% of the LUT, 5% of FF, 5% of BRAM, and 6% of DSP in FPGA resources are consumed to meet the design requirements. © 2021 IEEE.

关键词： Field programmable gate arrays (FPGA)

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