{"title":"Understanding stability of strontium titanate crystalline matrix for β and γ radiation by employing γ-γ TDPAC spectroscopy","authors":"Ashwani Kumar , Manjulata Sahu , B.S. Tomar , S.A. Khader , B.G. Vats , Y.K. Bhardwaj","doi":"10.1016/j.jnucmat.2025.156031","DOIUrl":"10.1016/j.jnucmat.2025.156031","url":null,"abstract":"<div><div>Strontium titanate perovskite plays a crucial role in the formation of the SYNROC phase assemblage, providing a favorable environment for the accommodation of <sup>90</sup>Sr from high level radioactive waste. The matrix experiences structural deterioration as a consequence of the radiations emanating from the immobilized radioactive waste. In an effort to comprehend the impact of β, γ radiation on the stability of the strontium titanate radioactive waste immobilization matrix, Time Differential Perturbed Angular Correlation (TDPAC) spectroscopy has been employed to analyze electric hyperfine interactions (HFI) in electron beam and γ irradiated strontium Titanate (STO). Previous research reported that TDPAC spectroscopy detected two distinct interaction sites, one associated with a static HFI and the other with dynamic HFI in the pristine STO sample. In the present work, STO was subjected to electron beam and γ radiation with doses ranging from 1 to 20 MGy to mimic the consequences of β and γ radiation in the immobilization matrix and HFIs are observed. The research findings show that there is no alteration in the static HFI which suggests radiation stability of the site with static electric field gradient (EFG). However, the dynamic HFI was observed to be sensitive to EB, γ irradiation. The relaxation of the dynamic EFG (<strong>τ</strong>) increased after irradiation but with dose its behaviour is contrasting. Due to the scarcity of literature on similar studies, it is not possible to offer any insights into the cause for change in dynamic HFI due to β, γ irradiation. Possibility of radiation induced defects creation and stability of STO matrix towards radiation damage is discussed.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"616 ","pages":"Article 156031"},"PeriodicalIF":2.8,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144662038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Critical Review of Machine Learning Analyses of Reactor Pressure Vessel Embrittlement and Hardening","authors":"Calum S. Cunningham, Susan R. Ortner","doi":"10.1016/j.jnucmat.2025.156027","DOIUrl":"10.1016/j.jnucmat.2025.156027","url":null,"abstract":"<div><div>Predicting the irradiation-induced embrittlement or hardening of nuclear reactor pressure vessels (RPVs) is key for safe long-term operation. Embrittlement trend curves (ETCs) are used to predict RPV embrittlement as a function of chemical and irradiation environment variables. There is increasing interest in applying machine learning (ML) to available mechanical testing data to produce ETCs, as opposed to conventional regression analysis. This work provides a focused review of the current state of ML applications to RPV embrittlement and identifies successes, failures and opportunities for the future.</div><div>The review shows that a wide range of ML techniques and approaches have been applied to the analysis of RPV steel embrittlement data. ML models are capable of predicting irradiation-induced embrittlement even more accurately than the leading analytical ETCs, however, this is only true when the models are interpolating within parameter spaces containing sufficient training data. When extrapolating – e.g., to a higher fluence – ML model accuracy can drastically diminish and, in some cases, fail to make physically reasonable predictions. ML investigations of the contributors to RPV embrittlement can reproduce the dominant known effects but are yet to provide insights not known from decades of coordinated research, mainly due to a lack of studies considering the effects of variables not already known to dominate embrittlement. Future work is recommended for ML to help advance the field of RPV embrittlement and perhaps improve predictions of RPV structural integrity to support long-term operation goals.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"616 ","pages":"Article 156027"},"PeriodicalIF":2.8,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144654696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lijuan Cui , Xunxiang Hu , Manuel Pouchon , Yufeng Du , Yong Dai
{"title":"Irradiation stability of M23C6 in representative reduced activation ferritic martensitic steels","authors":"Lijuan Cui , Xunxiang Hu , Manuel Pouchon , Yufeng Du , Yong Dai","doi":"10.1016/j.jnucmat.2025.156030","DOIUrl":"10.1016/j.jnucmat.2025.156030","url":null,"abstract":"<div><div>The irradiation stability of M<sub>23</sub>C<sub>6</sub> precipitates in three reduced activation ferritic/martensitic steels (RAFMs) was investigated following irradiation of high-energy protons and neutrons at doses up to 21 dpa and temperatures up to 520°C in the targets of the Swiss Spallation Neutron Source. M<sub>23</sub>C<sub>6</sub> precipitates in specimens before and after irradiation were characterized using atom probe tomography. The concentrations of Mn, Si, P and N increased significantly in M<sub>23</sub>C<sub>6</sub> precipitates, while the W concentration in M<sub>23</sub>C<sub>6</sub> precipitates decreased with increasing irradiation temperature. The spallation transmutation elements Ti, Sc, Ca and K were enriched in the M<sub>23</sub>C<sub>6</sub> precipitates of irradiated specimens, The enriched elements also showed strong segregation at the M<sub>23</sub>C<sub>6</sub>-matrix interface. Cr-rich clusters and small α’ precipitates were observed near the M<sub>23</sub>C<sub>6</sub> precipitates in F82H and Eurofer 97 specimens irradiated at about 20 dpa and 300°C. At higher irradiation temperatures (480°C and 520°C), Fe-rich clusters were formed inside M<sub>23</sub>C<sub>6</sub> precipitates.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"616 ","pages":"Article 156030"},"PeriodicalIF":2.8,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144613938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Insights into stress corrosion crack growth of 316NG heat-affected zone in simulated PWR primary water","authors":"Jun Xiao, Ting Xiao, Yu Qi Zheng, Yu Xiang Zhao, Qi Xu","doi":"10.1016/j.jnucmat.2025.156028","DOIUrl":"10.1016/j.jnucmat.2025.156028","url":null,"abstract":"<div><div>The SCC propagation behavior in the HAZ of 316NG remains insufficiently characterized. This study systematically evaluates SCC growth in HAZ specimens under simulated PWR primary water conditions (325 °C, 1200 mg/L B, 2 mg/L Li, both hydrogenated [30 mL (STP)/kg H₂] and oxygenated [0.5 ppm O₂] environments) at constant <em>K</em> = 30 MPa·m¹/². Compact tension (CT) specimens that contained artificial cracks positioned 1 mm and 4 mm from the weld fusion line were employed to asses SCC growth in the HAZ, where the crack propagation region extended to a normalized distance of 0.41–0.45 from the inner wall surface. Surprisingly, the HAZ exhibited crack growth rates marginally lower than or essentially comparable to those of the parent metal in both oxygenated and hydrogenated water environments. This suggests that compressive residual stresses in the SCC propagation region may mitigate the crack growth acceleration typically induced by strain hardening (up to 20 % hardness increase relative to the parent metal). High-resolution transmission electron microscopy (HRTEM) analysis demonstrated nickel (Ni) enrichment at grain boundaries ahead of advancing crack tips, attributed to rapid iron (Fe) diffusion along grain boundaries toward the crack tip and selective oxidation of Fe and chromium (Cr) at the crack tip. The oxide film formed a distinct bilayer structure, with an outer Fe₃O₄ magnetite layer and an inner FeCr₂O₄ spinel layer.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"616 ","pages":"Article 156028"},"PeriodicalIF":2.8,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144632914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Computation of sink strengths in complex microstructures","authors":"T. Jourdan , G. Adjanor","doi":"10.1016/j.jnucmat.2025.156021","DOIUrl":"10.1016/j.jnucmat.2025.156021","url":null,"abstract":"<div><div>A method is proposed for calculating sink strengths in complex microstructures, containing several sink types, some of which may be mobile. It is based on the estimation of mean lifetime of defects and on the fraction of defects absorbed by the different sinks. As an application, sink strengths for self-interstitial atoms are calculated with object kinetic Monte Carlo in microstructures containing vacancies and dislocations or grain boundaries. The transition from one-dimensional to three-dimensional diffusion of self-interstitial atoms and the role of vacancy mobility are investigated. Multiple-sink effects on sink strengths are shown to be present for all sinks, but only in specific diffusion regimes of self-interstitial atoms and vacancies. Results are discussed in light of existing expressions of sink strengths, and new expressions are proposed.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"616 ","pages":"Article 156021"},"PeriodicalIF":2.8,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144581204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shuo Cong , Ming Cao , Zuojiang Wang , Ziqi Cao , Ling Li , Yizhong Yang , Zhengyu Liu , Xujia Wang , Guang Ran
{"title":"Differential effects of Si/dpa ratio on the evolution of dislocation loops in Al-2.64 Mg alloy during in-situ irradiation","authors":"Shuo Cong , Ming Cao , Zuojiang Wang , Ziqi Cao , Ling Li , Yizhong Yang , Zhengyu Liu , Xujia Wang , Guang Ran","doi":"10.1016/j.jnucmat.2025.156016","DOIUrl":"10.1016/j.jnucmat.2025.156016","url":null,"abstract":"<div><div>Transmutated Si element is an important issue in the neutron irradiation of Al alloys. The Si production per dpa has been noticed to vary with the neutron energy spectrum, but the effect of Si/dpa ratio on the dislocation loop evolution has been rarely studied. In this work, the effect of Si/dpa ratio in Al-2.64 Mg alloy is in-situ quantitatively investigated by Si<sup>+</sup> irradiation at 100 °C with 1665, 468, and 57 appm/dpa. The higher the Si/dpa ratio, the smaller the loop size, but the higher the loop density in the matrix, which can be attributed to the high Si/dpa ratio leading to more lattice distortion and nucleation sites. Dislocation loops are preferentially formed around Al<sub>9</sub>Fe<sub>2-x</sub>Ni<sub>x</sub> precipitates due to the lattice mismatch at the interface. This phenomenon is more obvious at the low Si/dpa ratio. While Mg<sub>2</sub>Si precipitates have less effect on the formation of loops regardless of the Si/dpa ratio, because Al/Mg<sub>2</sub>Si interfaces are more likely to form a semi-coherent orientation and only result in mild lattice mismatch. But the type of dislocation loops is not affected by the lattice distortion and mismatch. In general, the Si atoms existed in Al lattice can significantly affect the dislocation loop evolution depending on the Si/dpa ratio. The current Si<sup>+</sup> irradiation results provide valuable data for understanding the transmutation behavior of Al alloys.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"616 ","pages":"Article 156016"},"PeriodicalIF":2.8,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144654645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Temperature effects on radiation damage in HCP-zirconium: A molecular dynamics study using a fine-tuned machine-learned potential","authors":"Xinfang Jia, Yu Bao, Shuo Cao, Ye Su, Ping Qian","doi":"10.1016/j.jnucmat.2025.156025","DOIUrl":"10.1016/j.jnucmat.2025.156025","url":null,"abstract":"<div><div>Zirconium has become an indispensable material in nuclear reactors due to its excellent corrosion resistance and low neutron absorption cross section. In this study, we fine-tune an efficient machine-learned interatomic potential for the pure Zr system. This potential demonstrates better performance in predicting defect properties, allowing us to conduct a comprehensive investigation of primary radiation damage through molecular dynamics simulations. We explore the threshold displacement energies of Zr at different temperatures and find that the variation in <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>d</mi></mrow></msub></math></span> with temperature is closely related to defect migration and recombination process. A series of cascade simulations with primary knock-on atom energies from 1 to 40 keV is conducted to investigate the effect of temperature on defect generation and clustering behavior in pure Zr. The results show that 10 keV serves as a critical value which large vacancy cluster begins to emerge, revealing distinct regimes of energy-dependence for defects. At low primary knock-on atom (PKA) energies, higher temperatures reduce both the number of steady defects and small-sized clusters. In contrast, at high PKA energies, the steady Frenkel pairs number <span><math><msub><mrow><mi>N</mi></mrow><mrow><mtext>s</mtext></mrow></msub></math></span> increases gradually with temperature, along with a greater occurrence of small-sized defect cluster. Moreover, it is likely to form large-sized defect clusters at lower temperature. Our findings provide critical insights into the irradiation damage mechanisms in Zr, offering theoretical guidance for the optimization of its radiation resistance.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"616 ","pages":"Article 156025"},"PeriodicalIF":2.8,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144597292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"In-reactor stress relaxation of 3-point bending CW-316 samples: Experiments and modelling","authors":"Guillaume Zumpicchiat , Benoit Tanguy , Pierre Gavoille , Valérie Vandenberghe , Julien Vidal","doi":"10.1016/j.jnucmat.2025.155990","DOIUrl":"10.1016/j.jnucmat.2025.155990","url":null,"abstract":"<div><div>3-point bending in-pile stress relaxation tests of cold-worked 316 stainless steel have been characterised in the mixed-spectrum OSIRIS reactor up to 7 dpa at 330<!--> <!-->°C. Relaxation kinetics were determined based on out of pile interphase measurements. The experimental design allows to study initial prescribed stress levels from 100 MPa up to 600 MPa and to investigate transient (primary) and steady-state (secondary) stress relaxation. Relaxation kinetics were found to be unaffected by initial prescribed stress but to depend on the cold work level of the samples. No incubation dose was observed, even for samples loaded at low initial stresses. Experimental results were interpreted using FE modelling to take into account the non-uniform stress distribution existing in 3-point bending samples loaded in the elasto-plastic domain. The linearly stress-dependent creep law, consisting of two terms representing transient and steady-state creep regimes, allows for a very good description of experimental relaxation kinetics all over the investigated stress range. The primary creep amplitude parameter was found to be dependent on the cold work level, which is consistent with literature. A steady state creep coefficient of 0.96 10<sup>−6</sup> MPa<sup>−1</sup>.dpa<sup>−1</sup> consistent with the values reported from fast reactors was obtained independently on the cold work level. Also it was shown that the stress relaxation ratio can be directly determined based on deflection relaxation ratio despite the non-uniform stress state and residual stresses into the samples.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"616 ","pages":"Article 155990"},"PeriodicalIF":2.8,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144581113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuling You , Liang Zhao , Jiamei Wang , Hui Zheng , Kai Chen , Lefu Zhang
{"title":"Flow-Accelerated Corrosion and Wall Thinning Mechanism of a Dissimilar Metal Welded Joint in the Secondary Loop Piping System of Pressurized Heavy Water Reactors","authors":"Yuling You , Liang Zhao , Jiamei Wang , Hui Zheng , Kai Chen , Lefu Zhang","doi":"10.1016/j.jnucmat.2025.156026","DOIUrl":"10.1016/j.jnucmat.2025.156026","url":null,"abstract":"<div><div>This study investigates the flow-accelerated corrosion (FAC) failure in a dissimilar metal weld joint (DMWJ) of a decommissioned secondary loop piping elbow from a nuclear plant after 20 years of operation in China. Comprehensive macroscopic and microscopic failure characterizations were conducted to elucidate the wall thinning mechanism. High-temperature electrochemical galvanic corrosion tests and computational fluid dynamics (CFD) simulations were performed to validate the proposed thinning mechanism. The results reveal that the SA106B carbon steel (CS) piping near the weld joint exhibits a typical scallop-shaped two-phase FAC morphology. Notably, the maximum wall thinning, reaching 1.404 mm, was observed in the SA106B heat-affected zone (HAZ) adjacent to the fusion boundary. The galvanic corrosion tests and CFD calculations confirm that the wall thinning is governed by a combination of galvanic corrosion, driven by the potential difference between CS and stainless steel (SS), and significant localized flow turbulence induced by weld reinforcement. The localized flow turbulence increases wall shear stress (WSS), liquid film thickness, and liquid droplet impingement (LDI), contributing to both erosive and corrosive effects, ultimately enhancing wall thinning. Special attention should be given to evaluating the thinning at the weld fusion line during non-destructive failure examinations of piping systems.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"616 ","pages":"Article 156026"},"PeriodicalIF":2.8,"publicationDate":"2025-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144613385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiahui Liu , Jesper Byggmästar , Zheyong Fan , Bing Bai , Ping Qian , Yanjing Su
{"title":"Utilizing a machine-learned potential to explore enhanced radiation tolerance in the MoNbTaVW high-entropy alloy","authors":"Jiahui Liu , Jesper Byggmästar , Zheyong Fan , Bing Bai , Ping Qian , Yanjing Su","doi":"10.1016/j.jnucmat.2025.156004","DOIUrl":"10.1016/j.jnucmat.2025.156004","url":null,"abstract":"<div><div>High-entropy alloys (HEAs) based on tungsten (W) have emerged as promising candidates for plasma-facing components in future fusion reactors, owing to their excellent irradiation resistance. To achieve physically realistic descriptions of primary radiation damage in such multi-component materials, we propose extended damage models and trained an efficient machine-learned interatomic potential for the MoNbTaVW quinary system. From cascade simulations at primary knock-on atom (PKA) energies of 1–150 keV, we fitted an extended arc-dpa model for quantifying radiation damage in MoNbTaVW. Furthermore, we performed 50 cascade simulations at the recoil energy of 150 keV with 27.648 million atoms to investigate the effect of PKA types (Mo, Nb, Ta, V, W). The results show that subcascade splitting effectively suppresses interstitial cluster formation, which is a key mechanism for enhancing radiation resistance in HEAs. Our findings provide valuable insights into the radiation resistance mechanisms in refractory body-centered cubic alloys and highlight the potential of machine learning approaches in radiation damage research.</div></div>","PeriodicalId":373,"journal":{"name":"Journal of Nuclear Materials","volume":"616 ","pages":"Article 156004"},"PeriodicalIF":2.8,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144581114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}