Nuclear Materials and Energy最新文献

{"title":"Evolution of elemental depth profiles on co-deposited layers at the divertor region of the WEST tokamak during its Phase 1 operations","authors":"A. Hakola ,&nbsp;J. Likonen ,&nbsp;T. Vuoriheimo ,&nbsp;E. Grigore ,&nbsp;I. Jõgi ,&nbsp;P. Paris ,&nbsp;A. Lagoyannis ,&nbsp;K. Mergia ,&nbsp;P. Tsavalas ,&nbsp;E. Fortuna-Zaleśna ,&nbsp;M. Balden ,&nbsp;E. Bernard ,&nbsp;M. Diez ,&nbsp;E. Tsitrone ,&nbsp;the WEST team","doi":"10.1016/j.nme.2025.101998","DOIUrl":"10.1016/j.nme.2025.101998","url":null,"abstract":"<div><div>We discuss detailed elemental, compositional, and structural properties of co-deposited layers formed on the special marker tiles at the divertor region of the WEST tokamak during its Phase 1 (2016–2021) plasma operations. The main new aspects are applying high depth and mass resolution, provided by a combination of state-of-the-art local analysis techniques, throughout the entire surface deposit and cross correlating the obtained results with published ones. We also show that proper comparison of the different data sets requires deconvoluting them with several experimental parameters, most importantly the lateral and depth resolutions as well as the analysis volume. The analyses reveal that the thickest deposits are formed towards the end of Phase 1, and the change is particularly noticeable after the C4 campaign with the longest exposure time and the largest number of boronizations carried out. Thin deposits (thickness up to 1–2 μm) are found on several poloidal regions of the analysed tiles, and they exhibit a clear sandwich-type of structure consisting of distinct B, C, O, and/or W-rich sublayers together with metallic impurities. Close to the inner strike point, thick deposits are measured (thickness several tens of micrometres) and they show complex, stratified structures, however, the same sublayer structure as for the thin deposits can still be recognized. On the thin deposits, the very surface is rich in B while for the thick deposits W dominates the topmost surface layers in the latter stages of Phase 1. For all the analysed samples, the superficial B and W concentrations are on average 10–30 at.% in addition to which high oxygen levels up to 15–40 at.% are measured. In the erosion-dominated regions, deposits can be observed but only in the microscopic scale inside recessed valleys, up to thicknesses of several micrometres. A dynamical erosion–deposition picture for the surface layers is confirmed, further contributing to their structure and composition.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"45 ","pages":"Article 101998"},"PeriodicalIF":2.7,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Densification behavior of ceramic tritium breeder pebble beds under vertical vibration: Effect of vibration parameters","authors":"Baoping Gong,&nbsp;Hao Cheng,&nbsp;Juemin Yan,&nbsp;Long Wang,&nbsp;Qixiang Cao,&nbsp;Long Zhang,&nbsp;Jiming Chen,&nbsp;Yongjin Feng","doi":"10.1016/j.nme.2025.101997","DOIUrl":"10.1016/j.nme.2025.101997","url":null,"abstract":"<div><div>Packing density of the tritium breeder pebble beds are closely related to the effective density of the lithium atom in the breeding cavities. And the higher the density of lithium atoms the higher the tritium breeding ratio. Therefore, in this work, the effect of vibration parameters on the densification behavior of tritium breeder pebble beds were investigated by Discrete element method (DEM) simulation. The findings indicate that vertical vibration can substantially enhance the densification of the mono-sized pebble bed. The average packing factor of the vibrated bed attains it’s maximum when the periodic boundary is employed. As the vibration frequency and amplitude increase, the average packing factor of the pebble bed experiences an initial rise, followed by a subsequent decrease. The effect of vibration intensity displays a similar pattern. Furthermore, as the vibration time is extended, the average packing factor of the pebble bed undergoes a gradual increase, ultimately reaching 0.6409 when the vibration time extends 200 s. The state is distinguished by the random close packing of mono-sized pebble beds. The findings presented in this paper contribute to the optimization of the fabrication and assembly process of solid blanket for fusion reactors.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"45 ","pages":"Article 101997"},"PeriodicalIF":2.7,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interaction of light ions with plasma-facing materials: Improved experimental accuracy and its impact on sputter yield simulations","authors":"E. Pitthan ,&nbsp;M. Fellinger ,&nbsp;B.Burazor Domazet ,&nbsp;P.M. Wolf ,&nbsp;J. Shams-Latifi ,&nbsp;F. Aumayr ,&nbsp;D. Primetzhofer","doi":"10.1016/j.nme.2025.101996","DOIUrl":"10.1016/j.nme.2025.101996","url":null,"abstract":"<div><div>This work investigates how corrections to fundamental parameters describing ion–solid interaction affect sputtering yield simulations based on the binary collision approximation. We review recent experimental assessments of electronic stopping power and short-range repulsive interatomic potentials for light plasma species (H, D, He) in plasma-facing material candidates (W, Fe, EUROFER97), and compare them to widely used semi-empirical and theoretical models. At low energies, discrepancies of up to 60% relative to SRIM-2013 and up to 210% relative to SRIM-1997 are identified for the specific energy loss, highlighting the need for improved input parameters. We assess the sensitivity of sputtering yields to these corrections using SDTrimSP simulations, and compare the results to new experimental sputter yield data obtained for re-deposited thin W, Fe, and EUROFER97 films on a high-sensitivity quartz crystal microbalance. Incorporating derived stopping powers and interatomic potentials into the simulation significantly reduces the discrepancies between experimental and simulated sputtering yields. Remaining uncertainties and model limitations, such as crystal structure effects and ion implantation, are discussed.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"45 ","pages":"Article 101996"},"PeriodicalIF":2.7,"publicationDate":"2025-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of DNN and RNN for the determination of the chemical composition of dimensionality-reduced LIBS spectra of fusion-based materials","authors":"S.J. Shetty ,&nbsp;M. Veis ,&nbsp;D. Sokulski ,&nbsp;P. Gąsior ,&nbsp;P. Veis","doi":"10.1016/j.nme.2025.101994","DOIUrl":"10.1016/j.nme.2025.101994","url":null,"abstract":"<div><div>Laser Induced Breakdown Spectroscopy (LIBS) is often referred to as an in-situ and rapid analysis technique. Although the experimental setup is relatively simple, the quantification of elements in a sample containing multiple elements poses challenges for faster and reliable quantification. The application of machine learning (ML) techniques is one of the optimal solutions to achieve the quantified result in real-time. This study investigates the performance of Deep Neural Network (DNN), Gated Recurrent Unit (GRU), and Bidirectional Long Short-Term Memory (Bi-LSTM) models in analyzing the composition of first wall materials of thermonuclear reactors. The dataset was modelled based on 7400 simulated spectra at a resolution of 4000, each row comprising 41,730 data points. Initial evaluations revealed that GRU and Bi-LSTM models outperformed DNN in capturing spectral data relationships, as indicated by higher R² scores and lower Mean Squared Error (MSE). To mitigate computational complexity and eliminate redundant data, a bottleneck approach was used, which reduced the feature space to 1024 while enhancing predictive performance. Further enhancements were achieved through hyperparameter tuning using Polar Bear Optimizer (PBO), leading to significant improvements in the overall model accuracy. The integration of dimensionality reduction and hyperparameter optimization techniques demonstrated significant enhancement in the predictive capabilities of Recurrent Neural Network (RNN) models. This study emphasizes the potential of machine learning techniques in addressing the challenges associated with the rapid quantification of elements in complex fusion related samples.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"45 ","pages":"Article 101994"},"PeriodicalIF":2.7,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine learning assisted optical emission spectroscopy to determine electron density and electron temperature in a cascaded arc plasma","authors":"Yong Wang ,&nbsp;Lina Zhou ,&nbsp;Cong Li ,&nbsp;Chunlei Feng ,&nbsp;Hongbin Ding","doi":"10.1016/j.nme.2025.101992","DOIUrl":"10.1016/j.nme.2025.101992","url":null,"abstract":"<div><div>High-density cascaded arc plasma has been widely applied in linear plasma devices (LPDs), in which the laser Thomson scattering (LTS) and optical emission spectroscopy (OES) are two popular diagnostic methods for the fundamental parameters, electron density (<em>n_e</em>) and electron temperature (<em>T_e</em>). However, the complicated LTS setup lacks spatial flexibility, while the accuracy of simple OES is limited. To address this, this study develops a machine learning model based on Support Vector Machine (SVM) with a grid search optimization. This model combines the high accuracy of LTS with the spatial flexibility of OES to predict <em>n_e</em> and <em>T_e</em> in cascaded arc plasma in DUT-PSI. The model utilizes four pairs of “double-peak” spectral lines, bypassing the complicated calibration for plasma emission spectrum. The results show that when discharged conditions are included as input (Case 1), the model achieves R² values around 0.97 for <em>n_e</em> and about 0.92 for <em>T_e</em>. When excluding discharge conditions and using only line intensity ratios (LIRs) as input (Case 2), the R² values for <em>n_e</em> and <em>T_e</em> remain approximately 0.90 and 0.80, respectively. The other index, root mean square error (RMSE), follows a similar tendency to R². These findings demonstrate that the predicted <em>n_e</em> and <em>T_e</em> in both cases are highly consistent with LTS measurements. Meanwhile, sensitivity analysis reveals that the model’s prediction accuracy is robust to the specific combination of spectral lines selected in both cases. Thus, by integrating the strengths of LTS and OES, this model features calibration-free for plasma spectroscopy and flexible spectral line selection, enabling comprehensive diagnosis of cascaded arc plasma and showing potential for application in other similar LPDs.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"45 ","pages":"Article 101992"},"PeriodicalIF":2.7,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of redeposited tungsten and EUROFER97 layers on deuterium retention in plasma-facing materials","authors":"Martina Fellinger ,&nbsp;Eduardo Pitthan ,&nbsp;Daniel Gautam ,&nbsp;Daniel Primetzhofer ,&nbsp;Friedrich Aumayr","doi":"10.1016/j.nme.2025.101990","DOIUrl":"10.1016/j.nme.2025.101990","url":null,"abstract":"<div><div>Retention of hydrogen isotopes in plasma-facing materials is a key challenge for safety and fuel efficiency of nuclear fusion reactors. In realistic reactor environments, simultaneous processes, such as erosion, redeposition, implantation and outgassing, can alter surface compositions and may affect hydrogen isotope retention. In this study, we investigate how thin redeposited layers of tungsten and EUROFER97 influence retention and release of previously implanted deuterium. Using a combination of Elastic Recoil Detection Analysis and Rutherford Backscattering Spectrometry, we quantify deuterium retention during in-situ annealing up to 600<!--> <!-->°C. Comparisons between coated and uncoated samples show that redeposited tungsten can act as partial diffusion barrier, preventing deuterium from outgassing. In contrast, redeposited EUROFER97 layers show no such effect and appear virtually transparent to deuterium diffusion. These findings emphasize the critical role of redeposited layers on fuel retention and have implications for wall lifetime estimates and fuel inventory control in fusion devices.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"45 ","pages":"Article 101990"},"PeriodicalIF":2.7,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stress corrosion cracking (SCC) in EUROFER RAFM steel subjected to Li-ceramics at 550 °C","authors":"M. Roldán,&nbsp;T. Hernández,&nbsp;F.J. Sánchez","doi":"10.1016/j.nme.2025.101991","DOIUrl":"10.1016/j.nme.2025.101991","url":null,"abstract":"<div><div>This study investigates the susceptibility of EUROFER reduced-activation ferritic-martensitic (RAFM) steel to stress corrosion cracking (SCC) when exposed to lithium ceramic breeder materials (HCPB environment) at 550 °C. A standardized experimental methodology based on the U-bend configuration was employed to apply well-defined stresses while preserving microstructural integrity. Specimens were subjected to prolonged exposure (up to 4300  h) in direct contact with lithium ceramics, and the resulting damage was characterized using scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). Complementary finite element simulations were performed to ensure the applied load remained within the elastic regime, evaluate the stress distribution, and identify the region experiencing maximum stress.</div><div>The results reveal that SCC is promoted by the formation of a thin, brittle, chromium-depleted surface layer, resulting from high-temperature oxidation. Cracks nucleate within this chemically and structurally degraded zone and propagate transgranularly under residual stress. A quantitative analysis of crack density and size demonstrates a clear correlation with exposure time and stress level, confirming the critical role of mechanical load in accelerating crack initiation and growth. These findings identify a significant degradation mechanism affecting EUROFER in breeder blanket operating conditions, underscoring the need to control both surface chemistry and residual stresses to ensure long-term structural reliability.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"45 ","pages":"Article 101991"},"PeriodicalIF":2.7,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145120880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding the oxidation of pure tungsten in air and its impact on the lifecycle of a fusion power plant","authors":"Rongrui Li ,&nbsp;Guillermo Álvarez ,&nbsp;Ayla Ipakchi ,&nbsp;Livia Cupertino-Malheiros ,&nbsp;Mark R. Gilbert ,&nbsp;Emilio Martínez-Pañeda ,&nbsp;Eric Prestat","doi":"10.1016/j.nme.2025.101988","DOIUrl":"10.1016/j.nme.2025.101988","url":null,"abstract":"<div><div>The oxidation of pure W and the sublimation of W oxide have been investigated to assess their impact on the lifecycle of a fusion power plant. Pure W has been oxidised at temperatures between 400 and 1050 °C and for durations ranging between 1 and 70 h. The formation of voids and cracks has been observed at temperatures above 600 °C, leading to the formation of dust or oxide spalling, which could be problematic in maintenance and waste-handling scenarios of a fusion power plant. Preferential oxidation taking place at the edge of the specimen was characterised, and its impact is discussed in relation to component design. Characterisation using electron microscopy and Raman spectroscopy revealed that the oxide scale is formed of three main layers: the inner layer is 30–50 nm thick WO<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> oxide, the middle layer is a 10–20 <span><math><mi>μ</mi></math></span>m thick of WO_2.72 and the outer layer is formed of WO_2.9/WO<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span> phases — whose thickness varies according to the total thickness of the oxide scale. The observed microstructure is discussed in relation to the parabolic-to-linear kinetics and its potential impact on tritium permeation and detritiation efficiency.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"45 ","pages":"Article 101988"},"PeriodicalIF":2.7,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stability of oxide phases in W–Cr–Y SMART alloys","authors":"Ryan D. Kerr ,&nbsp;Duc Nguyen-Manh ,&nbsp;Mark R. Gilbert ,&nbsp;Samuel T. Murphy","doi":"10.1016/j.nme.2025.101987","DOIUrl":"10.1016/j.nme.2025.101987","url":null,"abstract":"<div><div>The addition of Cr and Y into tungsten can dramatically increase the oxidation resistance of the first wall of a future fusion reactor, thereby reducing the risk of formation of volatile WO<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span> and the release of radioactive material. Experimental observations suggest that in these SMART alloys, yttrium facilitates the formation of a self-passivating layer of Cr₂O₃ at the metal surface, however, how exactly the Y does this remains unclear. Therefore, this work explores the phase stability of compounds consisting of W–Y–Cr–O and solution energies for the different components in tungsten using density functional theory. The simulations suggest that there is a substantial thermodynamic driving force for the formation of Y<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>, especially from yttrium and oxygen solvated in bulk tungsten. These observations suggest that the role of the yttrium may be to remove the oxygen that may inhibit Cr diffusion to the surface from the tungsten grains. This observation is in accordance with experimental studies showing that the oxidation resistance in the alloy occurs when the oxygen–yttrium ratio in the alloy is close to the stoichiometric ratio for Y<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"45 ","pages":"Article 101987"},"PeriodicalIF":2.7,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145107771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the corrosion behavior of static liquid Pb-16.7Li on the structural material CLF-1 steel","authors":"Haowen Deng ,&nbsp;Shouxi Gu ,&nbsp;Qiang Qi ,&nbsp;Guang-nan Luo","doi":"10.1016/j.nme.2025.101989","DOIUrl":"10.1016/j.nme.2025.101989","url":null,"abstract":"<div><div>In liquid Pb-Li tritium breeding blanket, the compatibility between liquid Pb-Li and Reduced-activation-ferritic-martensitic (RAFM) steel structure material is crucial for the successful application of the RAFM steel. Corrosion experiments on CLF-1 steel in static Pb-Li at 550 ℃ were conducted for up to 1200 h to figure out the corrosion behavior and mechanism. After exposure, a subset of specimens was cleaned by mixed acid dissolution, while the remaining samples were cold-mounted in resin for cross-sectional observation. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and Electron Backscatter Diffraction (EBSD) measurements were employed to characterize the corrosion behavior and reveal the corrosion mechanism. With increasing exposure time, corrosion initiates at grain boundaries and spreads laterally, producing boundary ditches, hollows, protrusions, and ultimately pebble‑like grains. It is proposed that corrosion occurs through the dissolution of Fe and Cr, facilitated by the diffusion of Li into the grain boundaries and grains, as well as the penetration and adsorption of Pb.</div></div>","PeriodicalId":56004,"journal":{"name":"Nuclear Materials and Energy","volume":"45 ","pages":"Article 101989"},"PeriodicalIF":2.7,"publicationDate":"2025-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145107770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}