{"title":"Digital twin model generation for crack propagation in steam generator tubes: Methods and implementation","authors":"Yingying Jiang , Hong Xia , Jinming Zhang , Yihu Zhu , Kaige Zhang , Xueying Huang , Wenzhe Yin , Peiqi Jiang","doi":"10.1016/j.anucene.2025.111697","DOIUrl":"10.1016/j.anucene.2025.111697","url":null,"abstract":"<div><div>Crack propagation in the steam generator tubes are critical factor influencing the safe operation of nuclear power plants. Accurate prediction of crack growth behavior is vital for effective equipment health monitoring and maintenance. A fundamental framework and key technologies for the implementation of digital twin technology in nuclear power plants were presented in this study. And a novel crack propagation digital twin model generation technique for steam generator tubes was introduced, which integrates experimental data with extended finite element simulation results. Particle Filter method and reinforcement learning were conducted to evaluate respective strengths and limitations in crack propagation prediction. Both experimental data and extended finite element simulation data were incorporated into the model training process. The results demonstrated that both digital twin model generation techniques have distinct applicability conditions and high accuracy. This study could provide new insights and technological approaches for the health monitoring of steam generator tubes.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"224 ","pages":"Article 111697"},"PeriodicalIF":1.9,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144563722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qian Li , Siwei Cai , Shengcai Zhang , XueChen Liu , Nianmei Zhang , Chen Hu , Xian Zeng , Yulong Mao , Weihua Cai
{"title":"Machine learning prediction for thermal–hydraulic parameters of semicircular-fin fuel bundle in lead–bismuth fast reactor","authors":"Qian Li , Siwei Cai , Shengcai Zhang , XueChen Liu , Nianmei Zhang , Chen Hu , Xian Zeng , Yulong Mao , Weihua Cai","doi":"10.1016/j.anucene.2025.111696","DOIUrl":"10.1016/j.anucene.2025.111696","url":null,"abstract":"<div><div>In this study, a machine learning approach is used to predict the thermal–hydraulic parameters of lead–bismuth eutectic flow in a new-style semicircular-fin rod bundles. With numerical simulation data, a novel micro segment method was used to extract data from 42 sub-channels and 19 fuel rods in the fluid domain and establish a database with 23,313 data points. Four machine learning models are used to predict the <em>h</em> and Δ<em>P</em> by normalizing the input parameters with model hyperparameter optimization. The results show that all of the four machine learning models have good prediction accuracy, with the error of less than 5% and MAPE were all within 1%. The performance of ANN model is better than that of the other three models in predicting new cases. It indicates that ANN model has a high accuracy in predicting thermal parameters under new cases, which verifies the applicability of the machine learning prediction method for multiple cases. This study confirmed the advantages of machine learning in predicting complex regular parameters, and proposed a new method for flow and heat transfer parameters prediction in the development of a subchannel analysis program for semicircular-fin rod bundles.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"224 ","pages":"Article 111696"},"PeriodicalIF":1.9,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144557041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Mathematical modeling and connectivity-enhanced segmentation of void fraction in two-phase flow CT images","authors":"Zirou Jiang , Shuo Xu , Jiahao Chang , Jichen Miao , Yuewen Sun","doi":"10.1016/j.anucene.2025.111693","DOIUrl":"10.1016/j.anucene.2025.111693","url":null,"abstract":"<div><div>The accurate assessment of two-phase flow in high-temperature gas-cooled reactors (HTGRs) is crucial for nuclear safety and operational efficiency. Void fraction, a key parameter for evaluating two-phase flow and core stability, can be derived from CT images. In static conditions, its measurement reduces to a segmentation task, whereas dynamic conditions require pixel-level corrections due to nonlinear tomographic effects. This study formulates mathematical models addressing these effects and proposes TransUNet-CC, an enhanced segmentation framework incorporating void connectivity priors. Experimental results on CT images reconstructed via FBP, ADMM-TV, and DRP confirm its superior performance, achieving a Dice coefficient of 0.8358 and RVFE of 6.93%. Notably, the DRP algorithm provides high-resolution, low-noise reconstructions, ensuring precise void fraction estimation. This work advances image-based diagnostics for nuclear reactor monitoring, offering a robust solution for complex flow conditions in HTGRs.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"224 ","pages":"Article 111693"},"PeriodicalIF":1.9,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144548691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Decoupling control for pressurizer pressure and water level in nuclear power plants based on a Proportional–Integral–Derivative Neural Network","authors":"Guofeng Fan, Shengyu Shen, Chunhui Dai","doi":"10.1016/j.anucene.2025.111687","DOIUrl":"10.1016/j.anucene.2025.111687","url":null,"abstract":"<div><div>The pressurizer plays a crucial role in nuclear power plants, ensuring reactor safety by maintaining stable pressure and water levels. It is characterized by nonlinearity, time-varying dynamics, and strong coupling. Conventional single-loop PID control systems often fail to decouple pressure and water level effectively, resulting in suboptimal performance, particularly under large load variations. To address these challenges, this study presents a novel decoupling control system based on a Proportional–Integral–Derivative Neural Network (PIDNN). The PIDNN is employed to mitigate the intense coupling effects between control loops. Furthermore, the Dung Beetle Optimizer (DBO) algorithm is integrated to optimize the initial weights of the PIDNN. A three-region pressurizer model is developed in MATLAB/Simulink for validation. The simulation results demonstrate that the proposed method significantly enhances the control performance and dynamic response speed of the pressurizer’s pressure and water level under typical load rejection transients in nuclear power plants, compared to traditional PID control. This method also exhibits advantages in robustness, adaptability, and engineering applicability, offering an innovative and effective solution for the decoupling control of pressurizers in nuclear power plants.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"224 ","pages":"Article 111687"},"PeriodicalIF":1.9,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144557042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Guo-Yan Zhou , Ling-Hao Liu , Xue-Yao Xiong , Xing Luo , Shan-Tung Tu
{"title":"Study on the mechanism of temperature fluctuation induced by coaxial jets in nuclear power systems","authors":"Guo-Yan Zhou , Ling-Hao Liu , Xue-Yao Xiong , Xing Luo , Shan-Tung Tu","doi":"10.1016/j.anucene.2025.111669","DOIUrl":"10.1016/j.anucene.2025.111669","url":null,"abstract":"<div><div>The mixing of fluid with different temperatures in the upper plenum results in temperature fluctuations, which can propagate to adjacent structures, potentially inducing fatigue damage. Current research primarily focuses on the temperature fluctuation characteristics of fluids and the mechanism of temperature fluctuation is still unclear. In this study, the mixing process of fluids in the upper plenum is modeled as a coaxial jet by using large eddy simulation (LES). The simulation model and method are experimentally validated. Then the distribution characteristics of the time-averaged velocity, pressure, temperature and RMS temperature at different directions and different heights are numerically obtained, respectively. By analyzing the transient temperature field, the formation mechanism of temperature fluctuation is clarified, that is, the oscillation of the central position of the cold fluid, the expansion and contraction of its control region and the changes in the shape of the region lead to the instability of the flow field.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"224 ","pages":"Article 111669"},"PeriodicalIF":1.9,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144535867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kun Tang , Yizhu Yang , Bin Yin , Xiyuan Cao , Wei Fu , Liang Zhao , Hui Dong
{"title":"Research on flow and heat transfer characteristics of built-in cooling system in shaft sealed reactor coolant pump","authors":"Kun Tang , Yizhu Yang , Bin Yin , Xiyuan Cao , Wei Fu , Liang Zhao , Hui Dong","doi":"10.1016/j.anucene.2025.111698","DOIUrl":"10.1016/j.anucene.2025.111698","url":null,"abstract":"<div><div>The built-in cooling system (BCS) constitutes a critical component of reactor coolant pump (RCP), whose structure is fundamentally determined by the nuclear reactor. Four-bearing mechanical-seal centrifugal pump is widely used in RCP. Operating parameters significantly influence the flow and heat transfer mechanisms in BCS, thereby affecting the service life and operational stability of RCP. Current research on the flow and heat transfer characteristics of BCS lacks comprehensive numerical simulations, which results in insufficient understanding of RCP fundamental operational mechanisms. Therefore, it is necessary to analyze the flow and heat transfer characteristics of BCS. A numerical simulation model established to simulate accurately the multi-passage large-span variable cross-section geometric structural characteristics of BCS in a certain RCP. An experimental platform is constructed for verification, and the flow and heat transfer patterns in BCS under standard operating conditions are obtained. Consequently, the influences of operational parameters on resistance and internal flow distribution are investigated.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"224 ","pages":"Article 111698"},"PeriodicalIF":1.9,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144535866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shuai Zhang , Yunqing Bai , Wenbo Li , Ming Jin , Tinyu Li , Mei Huang , Qiaoyan Chen , Fenglei Niu
{"title":"Accuracy analysis of different numerical methods on thermal stratification prediction of liquid metal","authors":"Shuai Zhang , Yunqing Bai , Wenbo Li , Ming Jin , Tinyu Li , Mei Huang , Qiaoyan Chen , Fenglei Niu","doi":"10.1016/j.anucene.2025.111690","DOIUrl":"10.1016/j.anucene.2025.111690","url":null,"abstract":"<div><div>The study of thermal stratification is of significant importance for the safety analysis of pool-type sodium fast reactors, and numerical simulation is an essential tool for investigating thermal stratification phenomena. This work evaluates the effectiveness of a couple of CFD solvers in predicting thermal stratification. It compares the impact of different discretization schemes on solution accuracy and analyzes the reasons for observed discrepancies. Several discretization schemes effectively capture thermal stratification, with the high-resolution scheme showing an average error of 4.2 % and a maximum temperature error of 7.7 K, while the second-order upwind scheme shows an average error of 2.59 % and a maximum temperature error of 6.9 K. Additionally, this study investigates the impact of different order difference schemes on the simulation results of thermal stratification. For conditions where the Richardson number (<em>Ri</em>) is greater than 0.82, the simulation results of the first-order upwind scheme are similar to those of the second-order upwind scheme.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"224 ","pages":"Article 111690"},"PeriodicalIF":1.9,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144548690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Guangyuan Jin , Weilian Li , Jinghu Bai , Rui Wang
{"title":"Study on flow characteristics and formation mechanism of air-water periodic flooding in two 3 × 3 rod bundle channels","authors":"Guangyuan Jin , Weilian Li , Jinghu Bai , Rui Wang","doi":"10.1016/j.anucene.2025.111706","DOIUrl":"10.1016/j.anucene.2025.111706","url":null,"abstract":"<div><div>The research on the characteristics and mechanisms of periodic flooding are important for the emergency treatment of nuclear power plants. Experimental investigations were carried out on the flooding phenomenon, the duration of various flooding regions, force analysis, and flow instability in two rod bundle channels. The flooding region can be divided into the onset flooding region and the completed flooding region. The average duration of flooding regions in Channel 1 is greater than that in Channel 2, so the channel with a smaller diameter provided larger waves, longer existence times, and expanded flooding conditions. Four forces acting on the liquid film are combined in different flooding regions to explain the formation mechanism of periodic flooding. The Kelvin–Helmholtz and Rayleigh-Taylor instabilities observed in the flooding and deflooding regions are shown to analyze the influence of interfacial instability on periodic flooding in different rod bundle channels.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"224 ","pages":"Article 111706"},"PeriodicalIF":1.9,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144548689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"High-precision eigenvalues of the neutron transport equation by the Carlvik method","authors":"Paolo Saracco , Nicolò Abrate , Sandra Dulla , Piero Ravetto","doi":"10.1016/j.anucene.2025.111672","DOIUrl":"10.1016/j.anucene.2025.111672","url":null,"abstract":"<div><div>High-precision results for solutions of neutron transport problems are important as a guidance to code developers and to understand the impact of physical and numerical approximations. The aim of this work is the determination of the eigenvalues of the transport equation in plane geometry, reaching results as accurate as one may desire, with practically no limitation in the number of exact digits required. The method proposed by Carlvik is re-visited and implemented through appropriate analytical manipulations within the <span>Mathematica</span>™ framework, exploiting some specific features of this software to keep a full control of the numerical precision throughout the whole calculation procedure. The Wynn-<span><math><mi>ɛ</mi></math></span> acceleration scheme is also used to improve the convergence trend. Some selected high-precision results are presented to illustrate the performance of the algorithm.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"224 ","pages":"Article 111672"},"PeriodicalIF":1.9,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144535865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Friederike Bostelmann, Steven E. Skutnik, William A. Wieselquist
{"title":"Introducing the SLICE Method for estimating pebble-bed reactor inventories at equilibrium operation with SCALE","authors":"Friederike Bostelmann, Steven E. Skutnik, William A. Wieselquist","doi":"10.1016/j.anucene.2025.111684","DOIUrl":"10.1016/j.anucene.2025.111684","url":null,"abstract":"<div><div>This paper introduces the SCALE Leap-In method for Cores at Equilibrium (SLICE) for estimating pebble-bed reactor equilibrium core isotopic inventories using capabilities in the SCALE code system, requiring only a small computational cluster and a few days of computation. This method uses an iterative approach that relies on (1) a surrogate spectrum model that captures spatial and time-dependent spectral conditions, (2) a multi-pass model that captures the pebble’s evolving nuclide inventory as a function of location and time in the core, and (3) a full-core model that captures the core’s spatial neutron flux distribution.</div><div>The SLICE approach is applied to a generic fluoride salt–cooled high-temperature reactor, demonstrating fuel inventory convergence through nuclide concentration inspection across iterations and comparisons for core realizations with varying discretizations. Results agree within <span><math><mo>∼</mo></math></span>5% with another state-of-the-art code, with differences attributed to input parameter or modeling assumption variations in the equilibrium generation methods.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"224 ","pages":"Article 111684"},"PeriodicalIF":1.9,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144523822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}