Annals of Nuclear Energy最新文献_第8页

Numerical investigation of spacer grid-induced flow disturbances and impact on fuel rod flow-induced vibrations 间隔栅诱导的流动扰动及其对燃料棒流致振动影响的数值研究

IF 2.3 3区工程技术

Annals of Nuclear Energy Pub Date : 2026-06-01 Epub Date: 2026-01-20 DOI: 10.1016/j.anucene.2026.112153

Yilong Li , Yan Guo , Junyong Liu, Hongyu Yang, Guangyun Min, Naibin Jiang

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A high-order hybrid spectral-Isogeometric solver for time-fractional neutron diffusion equations 时间分数中子扩散方程的高阶混合光谱等几何求解器

IF 2.3 3区工程技术

Annals of Nuclear Energy Pub Date : 2026-06-01 Epub Date: 2026-02-07 DOI: 10.1016/j.anucene.2026.112198

Ujwal Warbhe

{"title":"A high-order hybrid spectral-Isogeometric solver for time-fractional neutron diffusion equations","authors":"Ujwal Warbhe","doi":"10.1016/j.anucene.2026.112198","DOIUrl":"10.1016/j.anucene.2026.112198","url":null,"abstract":"<div><div>Accurate simulation of neutron diffusion is essential for nuclear reactor safety evaluation and core design. Time-fractional partial differential equations have emerged as effective models for describing anomalous diffusion in heterogeneous reactor media, but their numerical treatment is challenging due to the weak singularity at the initial time. Standard numerical schemes on uniform meshes suffer from suboptimal convergence, while graded mesh techniques, though improving accuracy, introduce implementation complexity and achieve only algebraic convergence rates. This work introduces a new computational framework that overcomes these limitations by synergistically combining a spectral Chebyshev discretization in time with Isogeometric Analysis (IGA) in space. The temporal basis, specifically tailored to capture the singular behavior, ensures exponential convergence without requiring graded meshes. For spatial discretization, high-order B-splines within the IGA setting provide both accuracy and geometric flexibility for complex reactor geometries. Rigorous stability and convergence analyses confirm spectral temporal accuracy and high-order spatial convergence. Numerical experiments demonstrate substantial improvements over state-of-the-art graded-mesh L1 schemes, validating the method’s potential for high-fidelity reactor simulations.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"231 ","pages":"Article 112198"},"PeriodicalIF":2.3,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146186192","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}

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Conceptual design of fast Molten salt reactors with novel secondary shutdown systems 新型二次关断快熔盐堆的概念设计

IF 2.3 3区工程技术

Annals of Nuclear Energy Pub Date : 2026-06-01 Epub Date: 2026-02-13 DOI: 10.1016/j.anucene.2026.112201

Yubin Go, Tongkyu Park, Sung Kyun Zee, Jae Uk Seo, Seong Jun Yoon

{"title":"Conceptual design of fast Molten salt reactors with novel secondary shutdown systems","authors":"Yubin Go, Tongkyu Park, Sung Kyun Zee, Jae Uk Seo, Seong Jun Yoon","doi":"10.1016/j.anucene.2026.112201","DOIUrl":"10.1016/j.anucene.2026.112201","url":null,"abstract":"<div><div>This study proposes and analyzes conceptual designs for novel secondary shutdown systems (SSS) in a chloride-fueled, fast-spectrum molten salt reactor (MSR) intended for maritime application. The design aims for 100 MW thermal power and 27 EFPY of operation (capacity factor of 0.9 with 30 year) with NaCl–KCl–UCl<sub>3</sub> fuel salt (42.9:20.3:36.8) using 19.75 w/o high-assay low-enriched uranium (HALEU). Core inlet and outlet temperatures are 540 °C, 620 °C (average 580 °C), and the ex-core fuel holdup volume is 6.5 m<sup>3</sup>. Two models are defined: Model-1 employs an SS316H reflector with 14 control drums plus 6 shutdown drums, while Model-2 uses SS316H reflector with 16 control drums and liquid-Pb drainable reflector replacing shutdown drums. Analyses are performed using OpenMC, with an assessment framework that includes k-eigenvalue, depletion, reactivity worth curves, and shutdown margin (SDM) requirements.</div><div>Over 27 EFPY of operation, the reactivity swing (Δρ) is −3795 pcm (Model-1) and −3888 pcm (Model-2), with EOC k<sub>eff</sub> values of 0.99985 and 1.00631, respectively. Up to the operational upper bound of 620 °C, there is about 600 pcm of negative reactivity insertion, as indicated by the isothermal temperature coefficient (ITC), which is −14.66 pcm/K for Model-1 and −14.82 pcm/K for Model-2. The Pb drain ensures a sufficient secondary-shutdown margin by providing up to 5922 pcm of negative worth at 100% drain. For the two models, safety margin checks with uncertainties reveal a margin of at least 500 pcm in both primary and secondary systems. With a total mass differential of 13.24 MT between Model-1 and Model-2 (209.57 MT and 222.81 MT, respectively), Model-2 also provides functional diversity through the drain. These findings offer baseline data for subsequent reflector design options (e.g., MgO) and coupled thermohydraulic/structural assessments, as well as comparison data for fast spectrum MSRs with a specified SSS.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"231 ","pages":"Article 112201"},"PeriodicalIF":2.3,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146186621","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}

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Numerical study on the vibration characteristics of 7-pin wire-wrapped fuel rods bundle in lead-bismuth eutectic flow with different constraint conditions 不同约束条件下铅铋共晶流动中7针线包燃料棒束振动特性的数值研究

IF 2.3 3区工程技术

Annals of Nuclear Energy Pub Date : 2026-06-01 Epub Date: 2026-01-23 DOI: 10.1016/j.anucene.2026.112164

Feifan Liu , Simian Qin , Quanyao Ren , Haidong Liu , Lele Zheng , Shanshan Bu , Penghui Zhang , Deqi Chen

{"title":"Numerical study on the vibration characteristics of 7-pin wire-wrapped fuel rods bundle in lead-bismuth eutectic flow with different constraint conditions","authors":"Feifan Liu , Simian Qin , Quanyao Ren , Haidong Liu , Lele Zheng , Shanshan Bu , Penghui Zhang , Deqi Chen","doi":"10.1016/j.anucene.2026.112164","DOIUrl":"10.1016/j.anucene.2026.112164","url":null,"abstract":"<div><div>This paper conducts a numerical investigation of flow characteristics and vibrations in a 7-pin wire-wrapped fuel rods bundle subjected to lead–bismuth eutectic (LBE) axial flow. In this paper, the flow characteristics of 7-pin rods bundle with two different wire-wrapped diameters is analyzed firstly. Then, the effect of the constraint of the adjacent rods to the center rods on the vibration response of the bundle is analyzed. Meanwhile, the effect of constraint conditions at the upper end of the bundle on the vibration behavior is discussed. It is indicated that increasing the wire-wrapped diameter changing from 1.9 mm to 2.0 mm impacts flow characteristics insignificantly. The fluid force on the central rod surface exceeds that on adjacent rods in the bundle configuration. Notably, when introducing normal contact between the wire of the center rod and the adjacent rods, the vibration displacement at the central rod’s midpoint decreases by 81 %, while the dominant frequency increases from 15 Hz to 40 Hz. As the upper-end constraint condition changes from simply support, Y-direction support to no support, the vibration displacement of the center rod changes significantly along the axial direction. When the lower end is fixed support and the upper end is no support, the vibration displacement of the upper end increases along the axial direction, and the root mean square at the upper end (Z = 1500 mm) reaches 68.70 μm. These findings provide a theoretical foundation for the design optimization of wire-wrapped rod bundles in lead–bismuth-cooled fast reactors.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"230 ","pages":"Article 112164"},"PeriodicalIF":2.3,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035540","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}

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Uncertainty quantification with MCMC algorithm for subchannel program based on steady and transient void fraction experiments 基于稳态和瞬态空隙率实验的子信道程序的MCMC算法不确定性量化

IF 2.3 3区工程技术

Annals of Nuclear Energy Pub Date : 2026-06-01 Epub Date: 2026-01-22 DOI: 10.1016/j.anucene.2026.112154

Hanyu Luo , Jiayu Long , Meiqi Song , Xiaojing Liu

{"title":"Uncertainty quantification with MCMC algorithm for subchannel program based on steady and transient void fraction experiments","authors":"Hanyu Luo , Jiayu Long , Meiqi Song , Xiaojing Liu","doi":"10.1016/j.anucene.2026.112154","DOIUrl":"10.1016/j.anucene.2026.112154","url":null,"abstract":"<div><div>Subchannel codes can provide higher-resolution results in reactor analysis than system codes, yet their uncertainty quantification (UQ) methodologies are less mature compared to those in thermal–hydraulic system codes. Current approaches predominantly focus on steady-state conditions with limited coverage of transient scenarios, and typically employ forward propagation based on parameter distributions derived from expert knowledge. This study develops a UQ framework based on COBRA-IV, combing inverse uncertainty quantification (IUQ) and forward propagation to analyse void fraction distributions for both steady-state and transient conditions of the Nuclear Power Engineering Corporation (NUPEC) Pressurized water reactor Subchannel and Bundle Tests (PSBT) benchmark. The framework also evaluates the effects of initial distributions of key parameters (slip ratio, turbulent mixing coefficient), and surrogate models including back-propagation neural network (BPNN), radial basis function (RBF) network, and Gaussian process regression (GPR). For steady-state conditions, all surrogate models successfully envelope the experimental data within consistent accuracy ranges, with calibrated root mean square error (RMSE) values ranging from 4.0% to 4.3%. In transient analysis, the uncertainty bands of void fraction remain within 10% variation relative to experimental values, indication low sensitivity to initial parameter distributions. All models capture over 88% of void fraction data points. After calibration, the BPNN model achieves an RMSE of 4.64%, while RBF and GPR reach 4.57% and 5.21%, respectively- a 40–45% improvement over the baseline RMSE of 8.15%. These results confirm the framework’s reliability across different implementation choices and its ability to enhance computational accuracy.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"230 ","pages":"Article 112154"},"PeriodicalIF":2.3,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035538","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}

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Investigation on the bypass flow characteristics of pebble bed core Gap structure in HTGR based on the fluid network method 基于流体网络方法的高温堆球层岩心间隙结构旁通流动特性研究

IF 2.3 3区工程技术

Annals of Nuclear Energy Pub Date : 2026-06-01 Epub Date: 2026-01-22 DOI: 10.1016/j.anucene.2026.112123

Wei Liu , Jinsong Guo , Qiong Wu , Yuhang Liu , Lixin Yang , Chaojun Wang

{"title":"Investigation on the bypass flow characteristics of pebble bed core Gap structure in HTGR based on the fluid network method","authors":"Wei Liu , Jinsong Guo , Qiong Wu , Yuhang Liu , Lixin Yang , Chaojun Wang","doi":"10.1016/j.anucene.2026.112123","DOIUrl":"10.1016/j.anucene.2026.112123","url":null,"abstract":"<div><div>Typical gap structures in the core of a pebble-bed high-temperature gas-cooled reactor (HTGR), including narrow core gaps and the Carbon Brick-Metal Reactor Gap, can induce helium bypass flow, which leads to local overheating that may affect the thermal efficiency and even safety. To investigate the effect of gap structures on bypass flow, the fluid network approach is used and a systematic core network model is established accordingly to represent the spatial features of the HTGR. With the core network model, the effect of gap structures, including the narrow gap width, keyway structure, and Carbon Brick-Metal Reactor Gap, on the bypass flow is analyzed. Results indicate that the keyway structure is the most effective factor in controlling the bypass flow and optimizing its flow resistance can significantly reduce the bypass flow ratio; the effect of narrow gap width on the bypass flow is limited while it is practically challenging to achieve a Carbon Brick-Metal Reactor Gap width range that can effectively restrict bypass flow. In addition, a temperature-based bypass flow severity index for characterizing the degree of impact of bypass flow on the temperature within the core is also proposed.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"230 ","pages":"Article 112123"},"PeriodicalIF":2.3,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035533","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}

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Improvement of HTGR lattice physics calculation based on advanced subgroup method 基于先进子群法的HTGR晶格物理计算改进

IF 2.3 3区工程技术

Annals of Nuclear Energy Pub Date : 2026-06-01 Epub Date: 2026-02-10 DOI: 10.1016/j.anucene.2026.112193

Yefan Hou, Yutong Wen, Ding She, Lei Shi

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High-precision rapid load following control strategy of a PWR under Plant Condition 1 based on reinforcement learning with preassigned-time convergence 基于预分配时间收敛强化学习的压水堆1状态下高精度快速负荷跟踪控制策略

IF 2.3 3区工程技术

Annals of Nuclear Energy Pub Date : 2026-06-01 Epub Date: 2026-02-07 DOI: 10.1016/j.anucene.2026.112180

Hongliang Liu , Yingming Song , Maoxin Liao

{"title":"High-precision rapid load following control strategy of a PWR under Plant Condition 1 based on reinforcement learning with preassigned-time convergence","authors":"Hongliang Liu , Yingming Song , Maoxin Liao","doi":"10.1016/j.anucene.2026.112180","DOIUrl":"10.1016/j.anucene.2026.112180","url":null,"abstract":"<div><div>Achieving safety and high-precision rapid load-following (L-F) capability in nuclear power plants (NPPs) poses persistent control challenges, especially under Plant Condition 1 (PC-1), which appears frequently and randomly during normal operation of NPPs. The primary objective of this article is to propose a control strategy for high-precision rapid L-F for a pressurized water reactor (PWR) with the random event of minor fuel element damage or steam generator leakage within permissible limits, which are classified as PC-1. Initially, to describe the dynamics of a nuclear reactor under PC-1, a core dynamics model with Markov jumping parameters is originally established. Subsequently, to suppress the influence of sensor noise and meet the requirement for rapid online observation of relative delayed neutron precursor density and average fuel temperature, a novel approach combining a practical finite-time observer with a fixed-time differentiator is developed. Furthermore, to compensate for unknown disturbances in real-time online, two innovative weight feedback updated laws for actor-critic networks are devised, ensuring practical preassigned-time convergence in reinforcement learning (RL). After that, accounting for the inevitability of observation and approximation errors in practical applications, a preassigned-time convergent L-F controller is designed to guarantees high-precision rapid L-F of PWR under PC-1. Ultimately, the effectiveness and feasibility of the proposed method is demonstrated by a simulation example.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"231 ","pages":"Article 112180"},"PeriodicalIF":2.3,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146186637","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}

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Ray Adaptive Stochastic Transport (RASTr): Importance sampling based variance reduction for characteristics method transport solvers 射线自适应随机输运（RASTr）：基于重要性抽样的特征法输运解的方差缩减

IF 2.3 3区工程技术

Annals of Nuclear Energy Pub Date : 2026-06-01 Epub Date: 2026-01-26 DOI: 10.1016/j.anucene.2026.112152

Owen Mylotte, Benoit Forget

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Assessment of self-interrogation safeguards Signatures for pebble bed reactor fuel 球床反应堆燃料自我询问保障标志的评估

IF 2.3 3区工程技术

Annals of Nuclear Energy Pub Date : 2026-06-01 Epub Date: 2026-01-21 DOI: 10.1016/j.anucene.2026.112155

Austen Ocanas , Farheen Naqvi , Sudeep Mitra , Jeremy Osborn

{"title":"Assessment of self-interrogation safeguards Signatures for pebble bed reactor fuel","authors":"Austen Ocanas , Farheen Naqvi , Sudeep Mitra , Jeremy Osborn","doi":"10.1016/j.anucene.2026.112155","DOIUrl":"10.1016/j.anucene.2026.112155","url":null,"abstract":"<div><div>Many next generation reactors propose the use of nontraditional nuclear fuel in the form of pebbles filled with thousands of fuel particles. While these next generation pebble bed reactors have been in development for decades, recent support for nuclear energy has bolstered the process, with many reactor designs proposed for deployment in the coming decade. An issue facing pebble bed reactors is safeguarding the fuel itself. Research on the burnup measurement systems is still evolving for developing a nondestructive assay method to quantify the amount of fissile material present in a used fuel pebble, creating a challenge for international safeguards design. The study presented here investigates the potential of neutron self-interrogation of spent fuel pebbles as an innovative method to implement materials accountability in these advanced reactors. Through reactor physics and fuel burnup simulations, spent fuel pebble material compositions are found and a method is developed to equate the delayed gamma-ray emissions resulting from the fissions induced by the pebble neutrons to the mass of key fissile actinides. The feasibility of this self-interrogation method is assessed, leading to the conclusion that the method is suitable for use in a passive counting mode employing a 4<em>π</em> detection geometry. As an example, the mass of <sup>235</sup>U, <sup>238</sup>U, <sup>239</sup>Pu and <sup>241</sup>Pu can be predicted at a precision of 4.1%, 0.86%, 13% and 13%, respectively, when measuring 100 end-of-life spent fuel pebbles over approximately 12 days.</div></div>","PeriodicalId":8006,"journal":{"name":"Annals of Nuclear Energy","volume":"230 ","pages":"Article 112155"},"PeriodicalIF":2.3,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035580","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}

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