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Near-wall void distribution characterization in pebble bed reactor using gamma-ray CT and DEM simulation 基于伽马射线CT和DEM模拟的球床反应器近壁孔隙分布表征
IF 2.1 3区 工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY Pub Date : 2026-02-09 DOI: 10.1016/j.nucengdes.2026.114813
Ahmed Jasim , Mauricio Maestri , Abdullah Al Zubaidi , Omar Farid , Muthanna Al-Dahhan
Accurate characterization of void-fraction distributions in pebble-bed reactors (PBRs) is essential for predicting flow, heat transfer, and neutronic behavior. High-fidelity experimental benchmark data for validating such predictions remain scarce, largely due to the challenges of non-invasive measurements. In this study, gamma-ray computed tomography (CT) was employed to measure radial and cross-sectional porosity in a laboratory-scale pebble bed containing 6cm graphite pebbles. A Discrete Element Method (DEM) simulation was implemented and validated against these measurements, then applied to the full-scale geometry of the Xe-100 high-temperature gas-cooled pebble-bed reactor. Analyses included radial and axial void-fraction profiles in the cylindrical section and conical base, with particular attention to near-wall oscillations at multiple axial levels. Both axially averaged profiles, integrating over extended bed sections, and locally resolved profiles, capturing fine-scale oscillations, were evaluated. Additional analyses examined cross-sectional void distributions and the effect of pebble recirculation. The DEM results reproduced the expected near-wall oscillatory layering with a characteristic wavelength of ∼1 dp and bulk void fractions near 0.40 and further showed that oscillatory patterns persist into the conical region, where the first trough shifts outward, and a broader near-wall gap develops. Recirculation studies, corresponding to 5,10, and 15 complete bed inventory cycles, showed that structural rearrangements occur mainly during the initial passes, after which the bed attains a quasi-steady configuration. Recirculation intensified near-wall oscillations, particularly in the lower regions, but had negligible impact on bulk porosity in the cylindrical section. In the cone, however, the void fraction was elevated during dynamic operation due to pebble drainage and upward void propagation. The findings support improved neutronic and thermal-hydraulic modeling and contribute to the design and safety assessment of next-generation pebble-bed systems.
球床反应器(PBRs)中空隙率分布的准确表征对于预测流动、传热和中子行为至关重要。用于验证此类预测的高保真实验基准数据仍然很少,主要是由于非侵入性测量的挑战。在本研究中,采用伽马射线计算机断层扫描(CT)测量了含6cm石墨卵石的实验室规模卵石床的径向和截面孔隙度。采用离散元法(DEM)进行了模拟,并对这些测量结果进行了验证,然后将其应用于Xe-100高温气冷球床反应器的全尺寸几何结构。分析包括圆柱形截面和锥形基座的径向和轴向空隙率分布,特别关注多轴向水平的近壁振荡。对轴向平均剖面和局部解析剖面进行了评估,其中轴向平均剖面整合了扩展的床段,局部解析剖面捕获了精细尺度的振荡。额外的分析检查了横截面空隙分布和卵石再循环的影响。DEM结果再现了预期的近壁振荡分层,其特征波长为~ 1 dp,体积空隙分数接近0.40,并进一步表明振荡模式持续到锥形区域,其中第一个槽向外移动,并形成更宽的近壁间隙。对应于5、10和15个完整床层库存周期的再循环研究表明,结构重排主要发生在初始阶段,之后床层达到准稳定配置。再循环加剧了近壁振荡,特别是在较低的区域,但对圆柱形截面的体积孔隙度的影响可以忽略不计。然而,在动态运行过程中,由于卵石排水和孔隙向上扩展,孔隙率升高。研究结果支持改进的中子和热水力建模,并有助于下一代球床系统的设计和安全评估。
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引用次数: 0
On the reactor physics implications of the use of UB2 as an additive within UN 在UN中使用UB2作为添加剂对反应堆物理的影响
IF 2.1 3区 工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY Pub Date : 2026-02-09 DOI: 10.1016/j.nucengdes.2026.114800
Olga Negri, Tim Abram, Joel Turner
The addition of UB₂ to UN fuel raises the onset temperature of its reaction with high-temperature steam. Natural boron contains 19.9% B-10, a strong neutron absorber that decays to Li-7 and He-4 upon neutron capture. This study explores the reactor physics implications of UN-UB₂ (10% UB₂) fuel with varying B-10 concentrations. Depletion analysis of an infinite lattice has shown that UN-UB₂ with 0–2% B-10 maintained cycle lengths similar to UN at equivalent U-235 enrichment and exhibited reduced reactivity swings. At 1500 effective full power days (EFPD), noble gas production in UN-UB₂ (1% B-10) was comparable to UO₂, with helium levels similar to krypton. The fuel temperature coefficient (FTC) was consistently negative across all materials, depletion levels, and temperatures. These results indicate that UN-UB₂ (1% B-10) offers comparable performance to UO₂ with benefits in enrichment, thermal conductivity, manageable helium generation, and effective reactivity control for LWRs.
向UN燃料中加入UB₂会提高其与高温蒸汽反应的起始温度。天然硼含有19.9%的B-10,这是一种强中子吸收剂,在中子捕获后会衰变成Li-7和He-4。本研究探讨了不同浓度B-10的UN-UB 2 (10% UB 2)燃料对反应堆物理的影响。对无限晶格的损耗分析表明,含有0-2% B-10的UN- ub₂在等效U-235富集时保持了与UN相似的周期长度,并表现出较小的反应性波动。在1500个有效满功率日(EFPD)下,UN-UB₂(1% B-10)的稀有气体产量与UO₂相当,氦气含量与氪气相似。燃料温度系数(FTC)在所有材料、耗竭水平和温度下均为负值。这些结果表明,UN-UB₂(1% B-10)在富集、导热性、可管理的氦生成和有效的反应性控制方面具有与UO₂相当的性能。
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引用次数: 0
Pre-conceptual neutronic design and feasibility analysis of a thorium-based lead‑bismuth cooled small modular reactor 钍基铅铋冷却小型模块化反应堆的概念前中子设计和可行性分析
IF 2.1 3区 工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY Pub Date : 2026-02-06 DOI: 10.1016/j.nucengdes.2026.114815
Xianbao Yuan , Changxiao Guan , Binhang Zhang , Yonghong Zhang
Small Modular Reactors (SMRs) are regarded as an important direction for future nuclear energy development due to their enhanced safety, flexible deployment capability and lower investment costs. In this study, neutronics simulations were carried out using OpenMC to design and analyze a long-life and inherently safe thorium-based lead‑bismuth cooled small modular reactor (TL-SMR). The core employs a thorium‑uranium fuel cycle and is cooled by liquid lead‑bismuth eutectic (LBE), enabling low-pressure operation and passive heat dissipation. The core can operate for more than 20 effective full-power years without refueling, achieving deep burnup. The key core parameters were analyzed, including control rod bank worths, radial and axial power factors, effective delayed neutron fractions and reactivity coefficients. The results indicate that the reactor exhibits negative reactivity coefficients, which ensure self-regulation under transient conditions. Throughout the operational cycle, the power distribution remains uniform and reasonable with sufficient shutdown margin. In summary, the TL-SMR demonstrates both long operational lifetime and favorable inherent safety characteristics. This study provides strong evidence for the technical feasibility of such reactors and offers valuable support for the further development of advanced reactor systems with inherent safety features.
小型模块化反应堆以其安全性强、部署灵活、投资成本低等优点被认为是未来核能发展的重要方向。在这项研究中,使用OpenMC进行了中子模拟,设计和分析了一个长寿命和固有安全的钍基铅铋冷却小型模块化反应堆(TL-SMR)。该堆芯采用钍-铀燃料循环,并通过液态铅-铋共晶(LBE)冷却,从而实现低压运行和被动散热。核心可以在不加油的情况下运行超过20年的有效满功率年,实现深度燃耗。分析了岩心的关键参数,包括控制棒组值、径向和轴向功率因子、有效延迟中子分数和反应性系数。结果表明,反应器的反应性系数为负,保证了瞬态条件下的自调节。在整个运行周期内,功率分配均匀合理,有足够的停机余量。总之,TL-SMR具有较长的运行寿命和良好的固有安全特性。本研究为该类反应堆的技术可行性提供了强有力的证据,并为进一步开发具有固有安全特性的先进反应堆系统提供了宝贵的支持。
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引用次数: 0
PIV study on subchannel cross-flow characteristics in 19-pin wire-wrapped bundle channels 19针绕线束通道子通道交叉流动特性的PIV研究
IF 2.1 3区 工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY Pub Date : 2026-02-06 DOI: 10.1016/j.nucengdes.2026.114810
Rongjie Li , Wukun Zhu , Chengwen Qiang , Minghan He , Han Wang , Lu Liu , Sicheng Wang , Dajun Fan
The China Initiative Accelerator Driven System (CiADS) holds significant promise in the transmutation of long-lived nuclear waste and the efficient utilization of nuclear fuel. Understanding the coolant flow characteristics within reactor fuel assemblies is crucial for ensuring the safe and economical operation of nuclear facilities. In this study, a visual hydraulic experimental platform was constructed to investigate the flow velocity distribution within the fuel assembly of CiADS. Utilizing particle image velocimetry technology, the transverse velocity distribution at subchannel interfaces within a 19-pin wire-wrapped fuel assembly was systematically investigated. The results reveal a distinct cosine-type distribution of the normalized transverse velocity at the interfaces between internal subchannels, with key flow features demonstrating robust Reynolds-number independence. Notably, significant wall-induced asymmetries alter this distribution at the interface between the internal subchannel and the side-wall subchannel. A novel transverse mixing model is developed, which shows close agreement with experimental data, confirming its predictive capability for inter-subchannel mixing in wire-wrapped bundles. This research further confirms the periodic disturbance characteristics induced by wire-wraps on transverse flow and provides a theoretical basis for predicting normalized transverse velocity in wire-wrapped bundles of different sizes, thereby deepening the understanding of the transverse mixing mechanism within rod bundles.
中国倡议加速器驱动系统(CiADS)在长寿命核废料的嬗变和核燃料的有效利用方面具有重大前景。了解反应堆燃料组件内的冷却剂流动特性对于确保核设施的安全和经济运行至关重要。本文建立了可视化的液压实验平台,对CiADS燃油组件内的流速分布进行了研究。利用粒子图像测速技术,系统研究了19针线包燃料组件子通道界面处的横向速度分布。结果表明,在内部子通道之间的界面处,归一化横向速度具有明显的余弦型分布,关键流动特征表现出鲁棒的雷诺数无关性。值得注意的是,显著的壁致不对称改变了内部子通道和侧壁子通道之间界面的分布。建立了一种新的横向混合模型,该模型与实验数据吻合较好,证实了该模型对线束中子通道间混合的预测能力。本研究进一步证实了绕丝对横向流动的周期性扰动特性,为预测不同尺寸绕丝束的归一化横向速度提供了理论依据,从而加深了对棒束内横向混合机理的认识。
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引用次数: 0
Comparative analysis of machine learning methods for correcting uranium loading measurement errors in pebble-bed HTGR spherical fuel elements 修正球床HTGR球形燃料元件铀负荷测量误差的机器学习方法比较分析
IF 2.1 3区 工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY Pub Date : 2026-02-06 DOI: 10.1016/j.nucengdes.2026.114807
Yanlong Wen, Hongjian Zhang, Haiyan Xiao, Qing Zhu, Liguo Zhang, Hong Li
Accurate determination of uranium loading in spherical fuel elements of high-temperature gas-cooled reactors (HTGRs) is essential for nuclear material accounting and reactor safety. Conventional γ-ray spectrometry based on a single characteristic peak (185.7 keV) suffers from significant variability due to differences in fuel sphere dimensions and TRISO particle distributions, yielding a coefficient of variation (CV) of around 1%.
In this study, a machine learning–based error correction framework was developed to enhance UO2 loading measurements. Three representative algorithms—Random Forest (RF), Support Vector Regression (SVR), and Multilayer Perceptron (MLP)—were trained on Geant4-simulated γ-ray data, incorporating both raw counts and composite features derived from six characteristic γ lines. Results show that all models reduced the CV to 0.3–0.4%, with the MLP achieving the best performance (CV ≤ 0.35%).
Further comparative analysis indicated that the three algorithms emphasize different mathematical solution spaces: RF captures discrete threshold effects, SVR provides smooth nonlinear fitting via kernel methods, and MLP flexibly spans a richer function space to approximate the mixed discrete–continuous nature of γ-ray attenuation. The integration of these perspectives demonstrates not only the potential of machine learning for nuclear material measurement but also the complementarity of different models in balancing accuracy, robustness, and interpretability.
This work provides a practical framework for improving non-destructive UO2 loading measurements in HTGR fuel elements, supporting more reliable nuclear material accounting and contributing to advanced reactor fuel management.
准确测定高温气冷堆(htgr)球形燃料元件中的铀负荷对核材料核算和反应堆安全至关重要。基于单个特征峰(185.7 keV)的常规γ射线谱法由于燃料球尺寸和TRISO颗粒分布的差异而存在显著的可变性,变异系数(CV)约为1%。在这项研究中,开发了一个基于机器学习的纠错框架来增强UO2负载测量。三种代表性算法——随机森林(RF)、支持向量回归(SVR)和多层感知器(MLP)——在geant4模拟的γ射线数据上进行了训练,包括原始计数和来自六条特征γ线的复合特征。结果表明,所有模型的CV值均在0.3 ~ 0.4%之间,其中MLP的性能最好(CV≤0.35%)。进一步的对比分析表明,这三种算法强调不同的数学解空间:RF捕获离散阈值效应,SVR通过核方法提供光滑的非线性拟合,MLP灵活地跨越更丰富的函数空间来近似γ射线衰减的混合离散-连续性质。这些观点的整合不仅展示了机器学习在核材料测量方面的潜力,而且还展示了不同模型在平衡准确性、鲁棒性和可解释性方面的互补性。这项工作为改进高温高压堆燃料元件的非破坏性UO2负荷测量提供了一个实用框架,支持更可靠的核材料核算,并有助于先进的反应堆燃料管理。
{"title":"Comparative analysis of machine learning methods for correcting uranium loading measurement errors in pebble-bed HTGR spherical fuel elements","authors":"Yanlong Wen,&nbsp;Hongjian Zhang,&nbsp;Haiyan Xiao,&nbsp;Qing Zhu,&nbsp;Liguo Zhang,&nbsp;Hong Li","doi":"10.1016/j.nucengdes.2026.114807","DOIUrl":"10.1016/j.nucengdes.2026.114807","url":null,"abstract":"<div><div>Accurate determination of uranium loading in spherical fuel elements of high-temperature gas-cooled reactors (HTGRs) is essential for nuclear material accounting and reactor safety. Conventional γ-ray spectrometry based on a single characteristic peak (185.7 keV) suffers from significant variability due to differences in fuel sphere dimensions and TRISO particle distributions, yielding a coefficient of variation (CV) of around 1%.</div><div>In this study, a machine learning–based error correction framework was developed to enhance UO<sub>2</sub> loading measurements. Three representative algorithms—Random Forest (RF), Support Vector Regression (SVR), and Multilayer Perceptron (MLP)—were trained on Geant4-simulated γ-ray data, incorporating both raw counts and composite features derived from six characteristic γ lines. Results show that all models reduced the CV to 0.3–0.4%, with the MLP achieving the best performance (CV ≤ 0.35%).</div><div>Further comparative analysis indicated that the three algorithms emphasize different mathematical solution spaces: RF captures discrete threshold effects, SVR provides smooth nonlinear fitting via kernel methods, and MLP flexibly spans a richer function space to approximate the mixed discrete–continuous nature of γ-ray attenuation. The integration of these perspectives demonstrates not only the potential of machine learning for nuclear material measurement but also the complementarity of different models in balancing accuracy, robustness, and interpretability.</div><div>This work provides a practical framework for improving non-destructive UO<sub>2</sub> loading measurements in HTGR fuel elements, supporting more reliable nuclear material accounting and contributing to advanced reactor fuel management.</div></div>","PeriodicalId":19170,"journal":{"name":"Nuclear Engineering and Design","volume":"450 ","pages":"Article 114807"},"PeriodicalIF":2.1,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190734","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}
引用次数: 0
CFD simulation methodology for large-scale heavy liquid metal facility relevant for MYRRHA: Application to E-SCAPE facility 与MYRRHA相关的大型重液态金属设施CFD模拟方法:在E-SCAPE设施中的应用
IF 2.1 3区 工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY Pub Date : 2026-02-04 DOI: 10.1016/j.nucengdes.2026.114798
S. Lopes , S. Keijers , L. Koloszar , J. Pacio , P. Planquart , K. Van Tichelen
This article is part of a series devoted to the analysis of pool thermal-hydraulic phenomena in heavy-liquid metal systems, combining experimental investigations with numerical simulations. The reference system is the Accelerator Driven System MYRRHA, currently under construction at SCK CEN (Belgium), which couples a particle accelerator with a pool-type research reactor cooled by lead-bismuth eutectic (LBE). An extensive experimental campaign has been carried out in the E-SCAPE facility, a 1/6-scaled LBE mockup of the primary vessel of MYRRHA, equipped with additional auxiliary circuits. In parallel, numerical studies based on computational fluid dynamics (CFD) are performed with the main objective of developing and validating robust CFD methodology capable of accurately simulating large-scale heavy-liquid metal experimental facilities. These studies allow the investigation of thermal-hydraulic phenomena and provide detailed insight into thermal and momentum fields. Model validation is achieved through systematic comparison between simulations and measurements obtained in E-SCAPE for a range of operating scenarios, including forced and natural circulation, symmetric and asymmetric loss-of-flow events, and asymmetric decay heat removal conditions.
In this paper, the numerical methodology to simulate the E-SCAPE facility under both steady-state and transient operating conditions is established. Since the natural circulation condition and the transition from forced to natural circulation are characterized by a strong coupling between thermal and momentum fields, detailed numerical description of the E-SCAPE core simulator, of the upper plena regions and of the external circuits are important. The main reason is that the flow rate in the core region is driven by the balance between the pressure drop and the thermal buoyancy effect and the flow rates in the external circuits are based on pressure losses through the valves, filters, and pumps. The impact of geometric simplifications of core plates and heaters, relative to the real configuration, is evaluated on the flow and on the temperature fields.
Furthermore, the effects of numerical mesh refinement and thermal boundary conditions are investigated under both iso-thermal and thermal forced circulation operating conditions. Simulated temperature distributions and pressure losses in the pool are compared against local experimental measurements. Finally, practical guidelines are proposed for CFD simulation of forced circulation, natural circulation, and transient conditions, addressing geometry simplifications, definition of fluid and solid domains, characterization of external circuits, and numerical strategies for transient initiation. The initial conditions for transient simulations are also computed and successfully compared with experimental data.
本文是分析重液态金属系统中池热水力现象系列文章的一部分,结合实验研究和数值模拟。参考系统是加速器驱动系统MYRRHA,目前正在比利时SCK CEN建造,该系统将粒子加速器与铅铋共晶(LBE)冷却的池型研究堆耦合在一起。在E-SCAPE设施中进行了广泛的实验活动,该设施是MYRRHA主船的1/6比例LBE模型,配备了额外的辅助电路。与此同时,基于计算流体动力学(CFD)的数值研究也在进行,其主要目标是开发和验证能够精确模拟大型重液态金属实验设施的稳健CFD方法。这些研究允许对热水力现象进行调查,并提供对热场和动量场的详细见解。通过对E-SCAPE中模拟和测量结果的系统比较,可以对一系列操作场景进行模型验证,包括强制循环和自然循环、对称和非对称失流事件以及非对称衰变热去除条件。本文建立了E-SCAPE设施稳态和暂态工况的数值模拟方法。由于自然循环条件和从强迫循环到自然循环的转变以热场和动量场之间的强耦合为特征,因此E-SCAPE核心模拟器、上全气区和外部电路的详细数值描述非常重要。主要原因是核心区域的流量是由压降和热浮力效应的平衡驱动的,而外部回路的流量是由通过阀门、过滤器和泵的压力损失驱动的。计算了芯板和加热器相对于实际结构的几何简化对流动和温度场的影响。此外,还研究了等温和热强迫环流工况下数值网格细化和热边界条件的影响。模拟的池内温度分布和压力损失与现场实验测量结果进行了比较。最后,提出了强制循环、自然循环和瞬态条件的CFD模拟的实用指南,包括几何简化、流体和固体域的定义、外部电路的表征以及瞬态启动的数值策略。计算了瞬态模拟的初始条件,并与实验数据进行了比较。
{"title":"CFD simulation methodology for large-scale heavy liquid metal facility relevant for MYRRHA: Application to E-SCAPE facility","authors":"S. Lopes ,&nbsp;S. Keijers ,&nbsp;L. Koloszar ,&nbsp;J. Pacio ,&nbsp;P. Planquart ,&nbsp;K. Van Tichelen","doi":"10.1016/j.nucengdes.2026.114798","DOIUrl":"10.1016/j.nucengdes.2026.114798","url":null,"abstract":"<div><div>This article is part of a series devoted to the analysis of pool thermal-hydraulic phenomena in heavy-liquid metal systems, combining experimental investigations with numerical simulations. The reference system is the Accelerator Driven System MYRRHA, currently under construction at SCK CEN (Belgium), which couples a particle accelerator with a pool-type research reactor cooled by lead-bismuth eutectic (LBE). An extensive experimental campaign has been carried out in the E-SCAPE facility, a 1/6-scaled LBE mockup of the primary vessel of MYRRHA, equipped with additional auxiliary circuits. In parallel, numerical studies based on computational fluid dynamics (CFD) are performed with the main objective of developing and validating robust CFD methodology capable of accurately simulating large-scale heavy-liquid metal experimental facilities. These studies allow the investigation of thermal-hydraulic phenomena and provide detailed insight into thermal and momentum fields. Model validation is achieved through systematic comparison between simulations and measurements obtained in E-SCAPE for a range of operating scenarios, including forced and natural circulation, symmetric and asymmetric loss-of-flow events, and asymmetric decay heat removal conditions.</div><div>In this paper, the numerical methodology to simulate the E-SCAPE facility under both steady-state and transient operating conditions is established. Since the natural circulation condition and the transition from forced to natural circulation are characterized by a strong coupling between thermal and momentum fields, detailed numerical description of the E-SCAPE core simulator, of the upper plena regions and of the external circuits are important. The main reason is that the flow rate in the core region is driven by the balance between the pressure drop and the thermal buoyancy effect and the flow rates in the external circuits are based on pressure losses through the valves, filters, and pumps. The impact of geometric simplifications of core plates and heaters, relative to the real configuration, is evaluated on the flow and on the temperature fields.</div><div>Furthermore, the effects of numerical mesh refinement and thermal boundary conditions are investigated under both iso-thermal and thermal forced circulation operating conditions. Simulated temperature distributions and pressure losses in the pool are compared against local experimental measurements. Finally, practical guidelines are proposed for CFD simulation of forced circulation, natural circulation, and transient conditions, addressing geometry simplifications, definition of fluid and solid domains, characterization of external circuits, and numerical strategies for transient initiation. The initial conditions for transient simulations are also computed and successfully compared with experimental data.</div></div>","PeriodicalId":19170,"journal":{"name":"Nuclear Engineering and Design","volume":"450 ","pages":"Article 114798"},"PeriodicalIF":2.1,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190733","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}
引用次数: 0
Selection of RANS turbulence model for calculating thermal hydraulics of fuel assemblies of LMC reactors at low Reynolds numbers 低雷诺数下LMC反应堆燃料组件热水力学计算的RANS湍流模型选择
IF 2.1 3区 工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY Pub Date : 2026-02-03 DOI: 10.1016/j.nucengdes.2025.114741
K. Sergeenko , A. Krutikov , L. Golibrodo , A. Zefirova , M. Shishlenin
Liquid metal coolants are considered in various fast neutron reactors. This paper presents the results of DNS calculations of heat and mass transfer processes of liquid metal coolants in the following regions: a parallel-plate channel, a rod bundle at cross-flow, and a channel with a step. The regions are selected in such a way as to describe as comprehensively as possible the thermal hydraulics of the fuel assembly, in which the spacing of the rods is carried out by the spacer grids. Two Reynolds numbers (Re = 2500 and 5000) and three Prandtl numbers (Pr = 0.0043, 0.0154 and 0.0324) are considered. The Prandtl numbers considered correspond to the liquid metal coolants used in fast neutron reactors: sodium, lead and lead bismuth, respectively.
The results of DNS simulations were compared with the data obtained using various RANS turbulence models (k-ε realizable two layer, k-ω SST, k-ε EB and k-ε V2F). It is shown that the k-ε V2F turbulence model describes the thermal-hydraulic processes in the best way. It recommends use this model for thermal-hydraulic calculations of fuel assemblies in reactor plants with liquid metal coolants at low Reynolds numbers.
It is shown that for all considered RANS turbulence models, the error in determining the heat transfer increases with increasing Peclet number in the parallel-plate channel. This is due to the features of the mechanisms of turbulent heat transfer for coolants at low Prandtl number.
The temperature profile is also compared with theoretical data. Satisfactory agreement is shown for all simulations in the area up to y+ ≈ 60. This can be used in experimental studies focused on determining the Nusselt number.
各种快中子反应堆都考虑使用液态金属冷却剂。本文给出了金属液态冷却剂在平行板通道、横流棒束通道和阶梯通道中传热传质过程的DNS计算结果。这些区域的选择方式是尽可能全面地描述燃料组件的热液压,其中棒的间距是由间隔网格进行的。考虑两个雷诺数(Re = 2500和5000)和三个普朗特数(Pr = 0.0043、0.0154和0.0324)。所考虑的普朗特数对应于快中子反应堆中使用的液态金属冷却剂:钠、铅和铅铋。将DNS模拟结果与各种RANS湍流模型(k-ε可实现两层,k-ω SST, k-ε EB和k-ε V2F)的数据进行了比较。结果表明,k-ε V2F湍流模型能较好地描述热工过程。它建议将该模型用于具有低雷诺数液态金属冷却剂的反应堆装置中的燃料组件的热工水力计算。结果表明,对于所有考虑的RANS湍流模型,计算换热的误差随着平行板通道中Peclet数的增加而增加。这是由于低普朗特数下冷却剂湍流传热机理的特点。温度分布也与理论数据进行了比较。在y+≈60范围内,所有的模拟结果都令人满意。这可以用于以确定努塞尔数为重点的实验研究。
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引用次数: 0
Erratum to “An analysis of the brittleness indices of SiC layer in the TRISO fuel,” Nucl. Eng. Design 446 (2026) 114614. 《TRISO燃料中碳化硅层脆性指标分析》的勘误,核。Eng。设计446(2026)114614。
IF 2.1 3区 工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY Pub Date : 2026-02-02 DOI: 10.1016/j.nucengdes.2026.114793
Makuteswara Srinivasan
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引用次数: 0
Analytic hierarchy process-based integrated assessment of IAEA'S 19 infrastructure criteria for small modular reactor technology assessment 基于层次分析法的国际原子能机构19项小型模块化反应堆技术评价基础设施标准综合评价
IF 2.1 3区 工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY Pub Date : 2026-02-02 DOI: 10.1016/j.nucengdes.2026.114797
Alif Imran Mohd Shuhaimi, Mohd Syukri Yahya, Shamsul Amri Sulaiman, Eli Syafiqah Aziman
Achieving Net Zero Emissions (NZE) by 2050 necessitates a strategic combination of renewable energy sources and dependable, clean baseload power. Nuclear energy is increasingly recognized as a critical element of this transition, with recent global policy endorsements calling for a tripling of nuclear capacity, underscoring its growing importance. Substantial expansion is anticipated not only in established nuclear markets but also in newcomer countries. However, initiating nuclear power programs poses significant challenges for newcomers, particularly due to massive capital investment, long-term infrastructure commitments, and the complexity of managing associated development risks. Reactor Technology Assessment (RTA) is therefore an essential process to ensure nuclear projects are delivered on time, within budget, safely, and to specifications. The International Atomic Energy Agency (IAEA) supports this process through its comprehensive framework of 19 infrastructure issues, addressing key dimensions such as national position, technical, and economic factors. This study presents a systematic, multi-criteria decision-making framework for conducting RTA, focusing on Small Modular Reactors (SMRs) as viable options for deployment in newcomer countries. The framework integrates the IAEA's infrastructure guidance with a PESTEL-based evaluation model. A case study is conducted for Malaysia to identify suitable SMRs for a Nuclear Hydrogen Hybrid System (NHHS). The assessment framework is validated using the Analytic Hierarchy Process (AHP), ensuring robustness and consistency in decision-making. The findings provide insights into aligning SMR technology selections with national requirements and risk profiles, offering a replicable methodology to support evidence-based decision-making in emerging nuclear energy programs.
到2050年实现净零排放(NZE)需要将可再生能源与可靠、清洁的基本负荷电力进行战略结合。核能越来越被认为是这一转型的关键因素,最近的全球政策支持要求将核能容量增加两倍,凸显了核能日益增长的重要性。预计不仅在已建立的核能市场,而且在新加入的国家也会有大幅扩张。然而,启动核电项目给新来者带来了重大挑战,特别是由于大规模的资本投资、长期的基础设施承诺,以及管理相关发展风险的复杂性。因此,反应堆技术评估(RTA)是确保核项目按时、在预算范围内、安全、符合规范交付的重要过程。国际原子能机构(IAEA)通过其19个基础设施问题的综合框架支持这一进程,解决国家地位、技术和经济因素等关键方面的问题。本研究提出了一个进行RTA的系统、多标准决策框架,重点关注小型模块化反应堆(smr)作为在新加入国家部署的可行选择。该框架将原子能机构的基础设施指南与基于pestel的评估模型相结合。马来西亚进行了一个案例研究,以确定适用于核氢混合动力系统(NHHS)的小型反应堆。采用层次分析法(AHP)对评估框架进行了验证,确保了决策的鲁棒性和一致性。这些发现为使小型堆技术选择与国家要求和风险概况相一致提供了见解,提供了一种可复制的方法,以支持新兴核能项目的循证决策。
{"title":"Analytic hierarchy process-based integrated assessment of IAEA'S 19 infrastructure criteria for small modular reactor technology assessment","authors":"Alif Imran Mohd Shuhaimi,&nbsp;Mohd Syukri Yahya,&nbsp;Shamsul Amri Sulaiman,&nbsp;Eli Syafiqah Aziman","doi":"10.1016/j.nucengdes.2026.114797","DOIUrl":"10.1016/j.nucengdes.2026.114797","url":null,"abstract":"<div><div>Achieving Net Zero Emissions (NZE) by 2050 necessitates a strategic combination of renewable energy sources and dependable, clean baseload power. Nuclear energy is increasingly recognized as a critical element of this transition, with recent global policy endorsements calling for a tripling of nuclear capacity, underscoring its growing importance. Substantial expansion is anticipated not only in established nuclear markets but also in newcomer countries. However, initiating nuclear power programs poses significant challenges for newcomers, particularly due to massive capital investment, long-term infrastructure commitments, and the complexity of managing associated development risks. Reactor Technology Assessment (RTA) is therefore an essential process to ensure nuclear projects are delivered on time, within budget, safely, and to specifications. The International Atomic Energy Agency (IAEA) supports this process through its comprehensive framework of 19 infrastructure issues, addressing key dimensions such as national position, technical, and economic factors. This study presents a systematic, multi-criteria decision-making framework for conducting RTA, focusing on Small Modular Reactors (SMRs) as viable options for deployment in newcomer countries. The framework integrates the IAEA's infrastructure guidance with a PESTEL-based evaluation model. A case study is conducted for Malaysia to identify suitable SMRs for a Nuclear Hydrogen Hybrid System (NHHS). The assessment framework is validated using the Analytic Hierarchy Process (AHP), ensuring robustness and consistency in decision-making. The findings provide insights into aligning SMR technology selections with national requirements and risk profiles, offering a replicable methodology to support evidence-based decision-making in emerging nuclear energy programs.</div></div>","PeriodicalId":19170,"journal":{"name":"Nuclear Engineering and Design","volume":"450 ","pages":"Article 114797"},"PeriodicalIF":2.1,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190256","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}
引用次数: 0
Initial study on the effects of TRISO-matrix interactions on TRISO particle performance in ceramic matrix dispersion microencapsulated fuel pellet 陶瓷基分散微胶囊燃料球团中TRISO-基质相互作用对TRISO颗粒性能影响的初步研究
IF 2.1 3区 工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY Pub Date : 2026-02-02 DOI: 10.1016/j.nucengdes.2026.114811
Junqiang Zheng , Jingyu Nie , Ya'nan He , Yingwei Wu , Jing Zhang , Yuanming Li , Shichao Liu , G.H. Su
This study presents a comprehensive multi-physics coupled analysis of TRISO-based Ceramic matrix Dispersion Microencapsulated (CDM) fuels, focusing on the debonding behavior at the TRISO-matrix interface under irradiation and thermal conditions, as well as the influence of TRISO-matrix interactions on TRISO particle performance within fuel pellets. A two-dimensional axisymmetric representative unit cell model was developed to investigate the effects of interfacial debonding characteristics under varying bonding parameters. Based on these findings, a three-dimensional pellet-scale multi-physics coupled model incorporating the Cohesive Zone Model was established to simulate interfacial debonding between TRISO particles and the matrix and its impact on structural integrity and failure probability. The model integrates irradiation-induced deformation, thermomechanical behavior, fission gas release, and interfacial damage evolution, enabling detailed evaluation of stress distribution and failure probability in both TRISO particles and SiC matrices.
Key results reveal that early-stage debonding at the TRISO-matrix interface is primarily driven by thermal expansion mismatch, with irradiation-induced deformation of the PyC layer contributing minimally. Smaller initial damage displacements accelerate interface failure, while larger failure displacements delay debonding but increase coating layer stresses, particularly in the SiC layer. At low temperatures, internal gas pressure within TRISO particles remains insufficient to induce critical tensile stress in the SiC layer, whereas PyC layer irradiation-induced deformation dominates the failure probability of the SiC coating. Additionally, spatial particle distribution and the surrounding matrix state significantly influence SiC coating failure, with localized high tensile stresses in narrow matrix regions posing risks for microcrack initiation.
Comparative analysis between pellet-scale CDM models and single TRISO particle models highlights the amplification of PyC layer hoop stresses due to particle-matrix interactions. The maximum failure probability of SiC coatings in pellet-scale models is approximately one order of magnitude higher than in single-particle simulations, underscoring the critical role of matrix confinement and interparticle interactions. These findings emphasize the necessity of considering high-packing-fraction configurations and interfacial bonding parameters in TRISO-based fuel performance assessments. Future work will focus on quantifying the effects of particle-matrix interactions on TRISO particle performance.
本研究对基于TRISO的陶瓷基质弥散微封装(CDM)燃料进行了全面的多物理场耦合分析,重点研究了辐照和热条件下TRISO-基质界面的脱键行为,以及TRISO-基质相互作用对燃料颗粒内TRISO颗粒性能的影响。建立了二维轴对称代表性单元胞模型,研究了不同键合参数对界面脱粘特性的影响。在此基础上,建立了包含内聚区模型的三维球团尺度多物理场耦合模型,模拟了TRISO颗粒与基体的界面脱粘及其对结构完整性和破坏概率的影响。该模型集成了辐照引起的变形、热力学行为、裂变气体释放和界面损伤演变,能够详细评估TRISO颗粒和SiC基体的应力分布和破坏概率。关键结果表明,TRISO-matrix界面的早期脱键主要是由热膨胀失配驱动的,PyC层的辐照变形贡献最小。较小的初始损伤位移加速了界面破坏,而较大的破坏位移延迟了剥离,但增加了涂层应力,特别是在SiC层中。在低温下,TRISO颗粒内部气体压力不足以在SiC层中产生临界拉伸应力,而PyC层辐照引起的变形主导了SiC涂层的破坏概率。此外,空间颗粒分布和周围的基体状态显著影响SiC涂层的失效,在狭窄的基体区域,局部的高拉伸应力会带来微裂纹萌生的风险。颗粒尺度CDM模型与单TRISO颗粒模型的对比分析表明,由于颗粒-基质相互作用,PyC层环向应力增大。颗粒尺度模型中SiC涂层的最大失效概率比单颗粒模拟高一个数量级,强调了基体约束和颗粒间相互作用的关键作用。这些发现强调了在triso燃料性能评估中考虑高填料分数结构和界面键合参数的必要性。未来的工作将集中于量化粒子-基质相互作用对TRISO粒子性能的影响。
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Nuclear Engineering and Design
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