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High-Order Coupling Method of Reaction Rate-Nuclide Density Used in Kylin-2 Code

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SSRN 2022年

作者： Hu, Yuying Liao, Hongkuan Yao, Dong Yu, Yingrui Zhou, Bingyan Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China China

The Projected Prediction-Correction(PPC) method is the most widely used method coupled transport calculation with burnup calculation nowadays, with linear rate(LR) interpolation for normal nuclides and logarithmic linear rate(LLR) interpolation for strong absorbent nuclides. This method has been verified by engineering, and also used in Kylin-2 code. By using PPC method, accurate results could be obtained in the case of detailed division of burnup steps, but the calculation efficiency is not high enough. In this study, the high-order coupling method of reaction rate-nuclide density and its substep calculation method are used to replace the coupling module of Kylin-2 code. By using the high-order coupling and substep calculation to replace parts of transport calculation, the amount of burnup steps is reduced, the calculation time is saved, and the calculation efficiency of Kylin-2 code is improved on the basis of maintaining the whole physical calculation accuracy as much as possible. © 2022, The Authors. All rights reserved.

关键词： Isotopes

A Power Regulation Strategy for Heat Pipe Cooled reactors Based on Deep Learning and Hybrid Data-Driven Optimization Algorithm

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SSRN 2023年

作者： Huang, Mengqi Peng, Changhong Du, Zhengyu Liu, Yu School of Nuclear Science and Technology University of Science and Technology of China Anhui Hefei230027 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Sichuan Chengdu610213 China

Heat pipe cooled reactors are suitable for deployment in remote or isolated areas as reliable small-scale power sources due to their good design characteristics. In order to cope with the real-time changing power demand in a dynamic environment, this study proposes a decision-making strategy for power regulation of heat pipe cooled reactors based on deep learning and hybrid data-driven optimization algorithm, which helps to achieve autonomous safe and efficient control of heat pipe cooled reactors under specific power demand. Firstly, an artificial neural network-based power prediction model for heat pipe cooled reactors is constructed;secondly, an evaluation criterion of power regulation schemes that integrates reactor safety and operational effectiveness is established based on utility theory, and finally, a hybrid data-driven optimization algorithm is proposed, which can quickly discover the power regulation scheme with the best utility under specific power demand. The strategy's effectiveness is verified by taking the power regulation process of the MegaPower heat pipe cooled reactor as an example. The results show that the strategy can make stable, accurate and near-optimal power regulation scheme decisions for arbitrary power demand within 20 seconds. © 2023, The Authors. All rights reserved.

关键词： Decision making

A Study of Flow Measurement Uncertainty Quantification Based on Sample Chunked Bayesian Inference

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SSRN 2024年

作者： Lu, Zihan Zhu, Yudi Zhou, Xinzhi Yu, Junhui Dong, Chenlong Wang, Hailin College of Electronic Information Sichuan University Chengdu610000 China National Key Laboratory of Science and Technology on Reactor System Design Technology Nuclear Power Institute of China Chengdu610213 China

The accuracy of coolant flow measurement of reactor Primary Circuit has a direct impact on the safety and stability of nuclear reactors. However, the presence of errors in the measurement method and instrumentation, as well as the fluid-heat coupling field in the pipeline, leads to a certain degree of uncertainty in the flow measurement. In this paper, an inverse uncertainty quantification method named Sample Chunked Bayesian Inference is proposed based on the establishment of a mathematical model of measurement uncertainty. The proposed method divides the input sample into a number of small samples with single peaks, and then uses each of these as observation sample of Bayesian Inference. The experiments show that the method can effectively quantify the systematic uncertainty and random uncertainty in the measured data. Moreover, compared with the traditional method that use input sample directly as observation sample, the proposed method has higher quantization accuracy. © 2024, The Authors. All rights reserved.

关键词： Bayesian networks

Optimized Moderator design and Analysis of a Pin-Type Supercritical Carbon Dioxide reactor Based on reactor Monte Carlo Code

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Optimized Moderator Design and Analysis of a Pin-Type Superc...

作者： Zhao, Xingyu Liu, Minyun Cui, Rongyi Huang, Shanfang Wang, Kan Lu, Chuan Department of Engineering Physics Tsinghua University Beijing100084 China Department of Engineering Physics Tsinghua University Beijing100084 China China Nuclear Power Engineering Co. Ltd. Beijing100840 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

This study analyzed an yttrium hydride (YH2) moderated supercritical carbon dioxide cooled reactor loaded with pin-type, beryllium oxide diluted oxide fuel elements to reduce the critical enrichment. The impact of the YH2 on the coolant void reactivity was studied along with a moderator zoning scheme to flatten the radial power distribution. The YH2 was added as hexagonal moderating rods at the center of the fuel assemblies. The core was modeled using the continuous-energy reactor Monte Carlo code (RMC) with the on-the-fly cross sections treatment. The results showed that the YH2 moderator increased the thermal fission and reduced the critical enrichment of the core with the same diluent volume fraction by more than 30%. The YH2 moderator significantly softened the neutron energy spectrum and reduced the neutron leakage upon core voiding, resulting in both a weaker positive spectral reactivity feedback and a weaker negative leakage reactivity feedback during core depressurization. For an UO2-loaded core, the YH2 gave a lower negative coolant void reactivity, while for a mixed oxide fuel (MOX)-loaded core with diluent volume fractions smaller than 35%, the spectral feedback was more important and the YH2 strongly reduced the positive coolant void reactivity to less than $1. Arranging the YH2 in the peripheral assemblies reduced the radial power peaking factor to 1.319. The study shows that the YH2 moderator can reduce the critical enrichment, make the core less sensitive to voiding, and can flatten the radial power distribution of a single-enrichment core through moderator zoning. [DOI: 10.1115/1.4056772] © 2023 American Society of Mechanical Engineers (ASME). All rights reserved.

关键词： Carbon dioxide

Quantitative Calculation of Bubble Pinning to Grain Boundaries in Uo2: A Phase-Field Study

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SSRN 2023年

作者： Liu, Wenbo La, Yongxiao Jiang, Yanbo Yun, Di Sun, Zhipeng Department of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

A phase-field model was established to simulate the pinning effect of fission bubbles on moving grain boundaries (GBs) in UO2 nuclear fuel. It was found that the average velocity of the GB at different positions was obviously different during the movement of the GB with the participation of bubbles. The simulation results also showed that the maximum pinning force of bubbles to the GBs is related to the GB energy and the ratio of bubble diameter to bubble spacing (2r/L). The maximum pinning force decreases with the reduction of the 2r/L, which is consistent with the theoretical analysis results. In addition, the logarithm of the average grain size R has a linear relationship with the logarithm of the bubble volume fraction fv. © 2023, The Authors. All rights reserved.

关键词： Grain boundaries

Analysis of Age of Information in Non-terrestrial Networks

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Analysis of Age of Information in Non-terrestrial Networks

2023 IEEE Globecom Workshops, GC Wkshps 2023

作者： Lu, Yanwu Yang, Howard H. Pappas, Nikolaos Geraci, Giovanni Ma, Chuan Quek, Tony Q. S. ZJU-UIUC Institute Zhejiang University Haining China Linköping University Department of Computer and Information Science Linköping Sweden Telefonica Research Universitat Pompeu Fabra Barcelona Spain Zhejiang Lab Hangzhou China Information System and Technology Design Pillar Singapore University of Technology and Design Singapore

ISBN: (纸本)9798350370218

Non-terrestrial networks (NTN), particularly low Earth orbit (LEO) satellite networks, have emerged as a promising solution to overcome the limitations of traditional terrestrial networks in the context of next-generation (6G) wireless systems. In this paper, we focus on analyzing the timeliness of information delivery in NTN through the concept of Age of Information (AoI). We propose an on-off process to approximate the service process between LEO satellites and a source node located on the Earth's surface. By utilizing stochastic geometry, we derive a closed-form expression for the time-average AoI in an NTN. This expression also applies to on-off processes with one component following an exponential distribution while the other has its probability density function supported on a bounded interval. Numerical results validate the accuracy of our analysis and demonstrate the impact of source status update rate and satellite constellation density on the time-average AoI. Our work fills a gap in the literature by providing a comprehensive analysis of AoI in NTN and offers new insights into the performance of LEO satellite networks. © 2023 IEEE.

关键词：

Optimized Moderator design and Analysis of a Pin-Type Supercritical Carbon Dioxide reactor Based on RMC 29

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Optimized Moderator Design and Analysis of a Pin-Type Superc...

2022 29th International Conference on Nuclear Engineering, ICONE 2022

作者： Zhao, Xingyu Liu, Minyun Cui, Rongyi Huang, Shanfang Wang, Kan Lu, Chuan Department of Engineering Physics Tsinghua University Beijing China Cnnc Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology Nuclear Power Institute of China Chengdu China China Nuclear Power Engineering Co. Ltd Beijing China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

ISBN: (纸本)9780791886502

This study analyzed an yttrium hydride (YH2) moderated supercritical carbon dioxide cooled reactor loaded with pin-type, beryllium oxide diluted oxide fuel elements to reduce the critical enrichment. The impact of the YH2 on the coolant void reactivity was studied along with a moderator zoning scheme to flatten the radial power distribution. The YH2 was added as hexagonal moderating rods at the center of the fuel assemblies. The core was modeled using the continuous-energy reactor Monte Carlo code, RMC, with the On-The-Fly cross sections treatment. The results showed that the YH2 moderator increased the thermal fission and reduced the critical enrichment of the core with the same diluent volume fraction by more than 30%. The YH2 moderator significantly softened the neutron energy spectrum and reduced the neutron leakage upon core voiding, resulting in both a weaker positive spectral reactivity feedback and a weaker negative leakage reactivity feedback during core depressurization. For an UO2-loaded core, the YH2 gave a lower negative coolant void reactivity, while for a MOX-loaded core with diluent volume fractions smaller than 35%, the spectral feedback was more important and the YH2 strongly reduced the positive coolant void reactivity to less than $1. Arranging the YH2 in the peripheral assemblies reduced the radial power peaking factor to 1.319. The study shows that the YH2 moderator can reduce the critical enrichment, make the core less sensitive to voiding, and can flatten the radial power distribution of a single-enrichment core through moderator zoning. © 2022 by ASME.

关键词： Carbon dioxide

Research of the Neutronics Performance Improvement Based on the Small Lead-Based Fast reactor Slbr-50

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SSRN 2022年

作者： Zhao, Chen Lou, Lei Zhang, Bin Zhou, Bingyan Peng, Xingjie Wang, Lianjie Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

design of high-performance lead-based fast reactor has already become a hotspot in the advanced reactor system. Research of the neutronics performance improvement is presented based on the small lead-based fast reactor SLBR-50. Parameter sensitivity analyses are conducted, including height-diameter ratio(H/D), reflector assembly arrangement, pitch-diameter ratio(P/D) in fuel assembly, fuel material and fuel enrichment partition. Numerical results of eigenvalue in burnup procedure, assembly power distribution and energy spectrum are analyzed. These results provide influences of these design parameters in quantity and the neutronics performance can be improved with parameter optimization. © 2022, The Authors. All rights reserved.

关键词： Fast reactors

POST-HOC INTERPRETABILITY BASED PARAMETER SELECTION for DATA ORIENTED NUCLEAR reactor ACCIDENT DIAGNOSIS system

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arXiv

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 China

During applying data-oriented diagnosis systems to distinguishing the type of and evaluating the severity of nuclear power plant initial events, it is of vital importance to decide which parameters to be used as the system input. However, although several diagnosis systems have already achieved acceptable performance in diagnosis precision and speed, hardly have the researchers discussed the method of monitoring point choosing and its layout. For this reason, redundant measuring data are used to train the diagnostic model, leading to high uncertainty of the classification, extra training time consumption, and higher probability of overfitting while training. In this study, a method of choosing thermal hydraulics parameters of a nuclear power plant is proposed, using the theory of post-hoc interpretability theory in deep learning. At the start, a novel Time-sequential Residual Convolutional Neural Network (TRES-CNN) diagnosis model is introduced to identify the position and hydrodynamic diameter of breaks in LOCA, using 38 parameters manually chosen on HPR1000 empirically. Afterwards, post-hoc interpretability methods are applied to evaluate the attributions of diagnosis model's outputs, deciding which 15 parameters to be more decisive in diagnosing LOCA details. The results show that the TRESCNN based diagnostic model successfully predicts the position and size of breaks in LOCA via selected 15 parameters of HPR1000, with 25% of time consumption while training the model compared the process using total 38 parameters. In addition, the relative diagnostic accuracy error is within 1.5% compared with the model using parameters chosen empirically, which can be regarded as the same amount of diagnostic reliability. Copyright © 2022, The Authors. All rights reserved.

关键词： Nuclear power plants