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Keywords = neutron irradiation effects

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15 pages, 4528 KiB  
Article
Changes in the Structure and Mechanical Properties of the SAV-1 Alloy and Structural Fe-Cr-Ni Steels After Long-Term Service as Core Materials in Nuclear Reactors
by Alexey Dikov, Sergey Kislitsin, Boris Ivanov, Ruslan Kiryanov and Egor Maksimkin
Materials 2025, 18(14), 3391; https://doi.org/10.3390/ma18143391 - 19 Jul 2025
Viewed by 270
Abstract
This article presents the results of studies of the degradation of the structure and mechanical properties of the core materials BN-350 fast neutron and research WWR-K reactors required to justify the service life extension of early-generation power and research reactors. Extending the service [...] Read more.
This article presents the results of studies of the degradation of the structure and mechanical properties of the core materials BN-350 fast neutron and research WWR-K reactors required to justify the service life extension of early-generation power and research reactors. Extending the service life of nuclear reactors is a modern problem, since most operating reactors are early-generation reactors that have exhausted their design lifespan. The possibility of extending the service life is largely determined by the condition of the structural materials of the nuclear facility, i.e., their residual resources must ensure safe operation of the reactor. For the SAV-1 alloy, the structural material of the WWR-K reactor, studies were conducted on witness samples which were in the active zone during its operation for 56 years. It was found that yield strength and tensile strength of the irradiated SAV-1 alloy decreased by 24–48%, and relative elongation decreased by ~2% compared to the unirradiated alloy. Inside the grains and along their boundaries, there were particles of secondary phases enriched with silicon, which is typical for aged aluminum alloys. For irradiated structural steels of power reactors, studied at 350–450 C, hardening and a damping nature of creep were revealed, caused by dispersion hardening and the Hall–Petch effect. Full article
(This article belongs to the Section Energy Materials)
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10 pages, 1130 KiB  
Article
DNA Damage Induced by Fast Neutron and Gamma Rays Evaluated Using qPCR
by Youichirou Matuo, Miyabi Yanami, Shingo Tamaki, Yoko Akiyama, Yoshinobu Izumi, Fuminobu Sato, Isao Murata and Kikuo Shimizu
Quantum Beam Sci. 2025, 9(3), 23; https://doi.org/10.3390/qubs9030023 - 7 Jul 2025
Viewed by 236
Abstract
We developed a novel dosimetric method using DNA molecules as a radiation sensor. The amount of neutron or gamma rays irradiated DNA damage was determined by evaluating the amount of DNA serving as a template for qPCR. The absorbed doses in the samples [...] Read more.
We developed a novel dosimetric method using DNA molecules as a radiation sensor. The amount of neutron or gamma rays irradiated DNA damage was determined by evaluating the amount of DNA serving as a template for qPCR. The absorbed doses in the samples were estimated using the tally of the “t-product” in the data from the PHITS Monte Carlo particle transport simulation code. The neutron fluence for each sample was measured using the niobium activation reaction 93Nb (n, 2n) 92mNb, and the absorbed dose per neutron fluence was estimated to be 7.1 × 10−11 Gy/(n/cm2). Based on the PHITS modeling, the effects of neutron beams are attributed to the combination of proton and alpha particle beams. The results from qPCR showed that neutrons caused more DNA damage than gamma rays. The qPCR method demonstrated that neutron irradiation caused 1.13-fold more DNA damage compared to gamma ray irradiation; however, this result did not show a statistically significant difference. This method we developed, using DNA molecules as a radiation sensor, may be useful for biodosimetry. Full article
(This article belongs to the Section Medical and Biological Applications)
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9 pages, 798 KiB  
Communication
Synthesis and Cancer Cell Targeting of a Boron-Modified Heat-Stable Enterotoxin Analog for Boron Neutron Capture Therapy (BNCT)
by Sota Okazaki, Yoshihide Hattori, Nana Sakata, Masaya Goto, Sarino Kitayama, Hiroko Ikeda, Toshiki Takei, Shigeru Shimamoto and Yuji Hidaka
Chemistry 2025, 7(4), 111; https://doi.org/10.3390/chemistry7040111 - 30 Jun 2025
Viewed by 473
Abstract
Heat-stable enterotoxin (STa) is a peptide toxin that induces acute diarrhea by binding to guanylyl cyclase C (GC-C) in intestinal epithelial cells. Interestingly, GC-C is highly expressed not only in intestinal cells but also in certain colorectal cancer cells, such as T84 and [...] Read more.
Heat-stable enterotoxin (STa) is a peptide toxin that induces acute diarrhea by binding to guanylyl cyclase C (GC-C) in intestinal epithelial cells. Interestingly, GC-C is highly expressed not only in intestinal cells but also in certain colorectal cancer cells, such as T84 and Caco-2 cells. This unique expression pattern provides STa as an effective candidate for therapeutic applications in cancer suppression or as a probe for detecting cancer cells. Recently, we developed attenuated forms of several STa analogs, including STa topological isomers, and evaluated their efficacy in detecting GC-C on Caco-2 cells, which enables the use of STa in human applications. Therefore, in this study, we investigated the potential application of a 10B-labeled STa derivative, [Mpr5,D-Lys16(BSH)]-STp(5–17) topological isomer, in boron neutron capture therapy (BNCT), for establishing a novel therapeutic strategy for colorectal cancer. The 10B-labeled STa peptide clearly exhibited Caco-2 cell killing activity upon neutron irradiation in a concentration-dependent manner, indicating that STa is an effective candidate drug for BNCT. To our knowledge, this is the first report of using STa in boron neutron capture therapy (BNCT). Full article
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33 pages, 5307 KiB  
Article
SiPM Developments for the Time-Of-Propagation Detector of the Belle II Experiment
by Flavio Dal Corso, Jakub Kandra, Roberto Stroili and Ezio Torassa
Sensors 2025, 25(13), 4018; https://doi.org/10.3390/s25134018 - 27 Jun 2025
Viewed by 277
Abstract
Belle II is a particle physics experiment working at an high luminosity collider within a hard irradiation environment. The Time-Of-Propagation detector, aimed at the charged particle identification, surrounds the Belle II tracking detector on the barrel part. This detector is composed by 16 [...] Read more.
Belle II is a particle physics experiment working at an high luminosity collider within a hard irradiation environment. The Time-Of-Propagation detector, aimed at the charged particle identification, surrounds the Belle II tracking detector on the barrel part. This detector is composed by 16 modules, each module contains a finely fused silica bar, coupled to microchannel plate photomultiplier tube (MCP-PMT) photo-detectors and readout by high-speed electronics. The MCP-PMT lifetime at the nominal collider luminosity is about one year, this is due to the high photon background degrading the quantum efficiency of the photocathode. An alternative to these MCP-PMTs is multi-pixel photon counters (MPPC), known as silicon photomultipliers (SiPM). The SiPMs, in comparison to MCP-PMTs, have a lower cost, higher photon detection efficiency and are unaffected by the presence of a magnetic field, but also have a higher dark count rate that rapidly increases with the integrated neutron flux. The dark count rate can be mitigated by annealing the damaged devices and/or operating them at low temperatures. We tested SiPMs, with different dimensions and pixel sizes from different producers, to study their time resolution (the main constraint that has to satisfy the photon detector) and to understand their behavior and tolerance to radiation. For these studies we irradiated the devices to radiation up to 5×10111 MeV neutrons equivalent (neq) per cm2 fluences; we also started studying the effect of annealing on dark count rates. We performed several measurements on these devices, on top of the dark count rate, at different conditions in terms of overvoltage and temperatures. These measurements are: IV-curves, amplitude spectra, time resolution. For the last two measurements we illuminated the devices with a picosecond pulsed laser at very low intensities (with a number of detected photons up to about twenty). We present results mainly on two types of SiPMs. A new SiPM prototype developed in collaboration with FBK with the aim of improving radiation hardness, is expected to be delivered in September 2025. Full article
(This article belongs to the Section Physical Sensors)
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13 pages, 4454 KiB  
Article
Proton Irradiation and Thermal Restoration of SiPMs for LEO Missions
by Alexis Luszczak, Lucas Finazzi, Leandro Gagliardi, Milagros Moreno, Maria L. Ibarra, Federico Golmar and Gabriel A. Sanca
Instruments 2025, 9(3), 15; https://doi.org/10.3390/instruments9030015 - 26 Jun 2025
Viewed by 325
Abstract
Silicon Photomultipliers (SiPMs) are optical sensors widely used in space applications due to their high photon detection efficiency, low power consumption, and robustness. However, in Low Earth Orbit (LEO), their performance degrades over time due to prolonged exposure to ionizing radiation, primarily from [...] Read more.
Silicon Photomultipliers (SiPMs) are optical sensors widely used in space applications due to their high photon detection efficiency, low power consumption, and robustness. However, in Low Earth Orbit (LEO), their performance degrades over time due to prolonged exposure to ionizing radiation, primarily from trapped protons and electrons. The dominant radiation-induced effect in SiPMs is an increase in dark current, which can compromise detector sensitivity. This study investigates the potential of thermal annealing as a mitigation strategy for radiation damage in SiPMs. We designed and tested PCB-integrated heaters to selectively heat irradiated SiPMs and induce recovery processes. A PID-controlled system was developed to stabilize the temperature at 100 °C, and a remotely controlled experimental setup was implemented to operate under irradiation conditions. Two SiPMs were simultaneously irradiated with 9 MeV protons at the EDRA facility, reaching a 1 MeV neutron equivalent cumulative fluence of (9.5 ± 0.2) × 108 cm−2. One sensor underwent thermal annealing between irradiation cycles, while the other served as a control. Throughout the experiment, dark current was continuously monitored using a source measure unit, and I–V curves were recorded before and after irradiation. A recovery of more than 39% was achieved after only 5 min of thermal cycling at 100 °C, supporting this recovery approach as a low-complexity strategy to mitigate radiation-induced damage in space-based SiPM applications and increase device lifetime in harsh environments. Full article
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15 pages, 2038 KiB  
Article
Mechanical Tensile Response of Ni–Graphene Nanocomposites in Hydrogen-Irradiation-Coupled Environments Using Molecular Dynamics Simulations
by Tonghe Liu, Xiaoting Yuan and Hai Huang
Nanomaterials 2025, 15(13), 970; https://doi.org/10.3390/nano15130970 - 22 Jun 2025
Viewed by 303
Abstract
In Gen-IV nuclear reactors, structural materials must endure unprecedented levels of neutron irradiation and hydrogen exposure, posing significant challenges for traditional Ni-based alloys. This study evaluates Ni–graphene nanocomposites (NGNCs) as a promising solution, leveraging their inherent radiation tolerance and hydrogen diffusion suppression. Using [...] Read more.
In Gen-IV nuclear reactors, structural materials must endure unprecedented levels of neutron irradiation and hydrogen exposure, posing significant challenges for traditional Ni-based alloys. This study evaluates Ni–graphene nanocomposites (NGNCs) as a promising solution, leveraging their inherent radiation tolerance and hydrogen diffusion suppression. Using molecular dynamics simulations, we investigate how Ni/graphene interfaces influence mechanical properties under combined hydrogen permeation and displacement damage. Key parameters, such as hydrogen concentration, displacement damage level, strain rate, and temperature, are systematically varied to assess their impact on stress–strain behavior (including Young’s modulus and tensile strength), with comparisons to single-crystal nickel. Our findings reveal that NGNCs exhibit distinct mechanical responses characterized by serrated stress–strain curves due to interfacial slip. Hydrogen and irradiation effects are complex: low hydrogen levels can increase Young’s modulus, while higher concentrations and irradiation generally degrade strength, with NGNCs being more affected than single-crystal nickel. Additionally, NGNCs show enhanced thermal stability but increased strain rate sensitivity. These results provide critical insights for designing materials that balance reinforcement with environmental resilience in nuclear applications. Full article
(This article belongs to the Section Theory and Simulation of Nanostructures)
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13 pages, 1068 KiB  
Article
Styrene–Maleic Acid Copolymer-Based Nanoprobes for Enhanced Boron Neutron Capture Therapy
by Mingjie Zhang, Shanghui Gao, Kai Yang, Benchun Jiang, Wei Xu, Waliul Islam, Shinnosuke Koike, Yusei Kinoshita, Hiroto Nakayama, Jianrong Zhou, Kazumi Yokomizo and Jun Fang
Pharmaceutics 2025, 17(6), 738; https://doi.org/10.3390/pharmaceutics17060738 - 4 Jun 2025
Viewed by 477
Abstract
Background/Objectives: Boron neutron capture therapy (BNCT) is a promising, less-invasive anticancer treatment. However, the development of effective boron-based agents (BNCT probes) remains a critical and challenging issue. Previously, we developed a styrene–maleic acid (SMA) copolymer conjugated with glucosamine, encapsulating boronic acid, which [...] Read more.
Background/Objectives: Boron neutron capture therapy (BNCT) is a promising, less-invasive anticancer treatment. However, the development of effective boron-based agents (BNCT probes) remains a critical and challenging issue. Previously, we developed a styrene–maleic acid (SMA) copolymer conjugated with glucosamine, encapsulating boronic acid, which exhibited tumor-targeted distribution via the enhanced permeability and retention (EPR) effect. Building upon this approach, in this study, we designed and synthesized a series of SMA-based polymeric probes for BNCT and evaluated their biological activities, with a particular focus on tumor-targeting properties. Methods: Two SMA-based BNCT nanoprobes, SMA–glucosamine conjugated Borax (SG@B) and SMA-conjugated aminophenylboronic acid encapsulating tavaborole (S-APB@TB), were designed and synthesized. The boron content in the conjugates was quantified using inductively coupled plasma mass spectrometry (ICP-MS), while particle sizes were measured via dynamic light scattering (DLS). In vitro cytotoxicity was assessed using the MTT assay in mouse colon cancer C26 cells. The tissue distribution of the conjugates was analyzed in a mouse sarcoma S180 solid tumor model using ICP-MS. Results: Both SG@B and S-APB@TB formed nanoformulations with average particle sizes of 137 nm and 99 nm, respectively. The boron content of SG@B was 2%, whereas S-APB@TB exhibited a significantly higher boron content of 14.4%. Both conjugates demonstrated dose-dependent cytotoxicity against C26 cells, even in the absence of neutron irradiation. Notably, tissue distribution analysis following intravenous injection revealed higher boron concentrations in plasma and tumor tissues compared to most normal tissues, with S-APB@TB showing particularly favorable tumor accumulation. Conclusions: These findings highlight the tumor-targeting potential of SMA-based BNCT nanoprobes. Further investigations are warranted to advance their clinical development as BNCT agents. Full article
(This article belongs to the Section Nanomedicine and Nanotechnology)
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24 pages, 3097 KiB  
Review
Advancements and Development Trends in Lead-Cooled Fast Reactor Core Design
by Cong Zhang, Ling Chen, Yongfa Zhang and Song Li
Processes 2025, 13(6), 1773; https://doi.org/10.3390/pr13061773 - 4 Jun 2025
Cited by 1 | Viewed by 1043
Abstract
Motivated by the growth of global energy demand and the goal of carbon neutrality, lead-cooled fast reactors, which are core reactor types of fourth-generation nuclear energy systems, have become a global research hotspot due to their advantages of high safety, nuclear fuel breeding [...] Read more.
Motivated by the growth of global energy demand and the goal of carbon neutrality, lead-cooled fast reactors, which are core reactor types of fourth-generation nuclear energy systems, have become a global research hotspot due to their advantages of high safety, nuclear fuel breeding capability, and economic efficiency. However, its engineering implementation faces key challenges, such as material compatibility, closed fuel cycles, and irradiation performance of structures. This paper comprehensively reviews the latest progress in the core design of lead-cooled fast reactors in terms of the innovation of nuclear fuel, optimization of coolant, material adaptability, and design of assemblies and core structures. The research findings indicate remarkable innovation trends in the field of lead-cooled fast reactor core design, including optimizing the utilization efficiency of nuclear fuel based on the nitride fuel system and the traveling wave burnup theory, effectively suppressing the corrosion effect of liquid metal through surface modification technology and the development of ceramic matrix composites; replacing the lead-bismuth eutectic system with pure lead coolant to enhance economic efficiency and safety; and significantly enhancing the neutron economy and system integration degree by combining the collaborative design strategy of the open-type assembly structure and control drums. In the future, efforts should be made to overcome the radiation resistance of materials and liquid metal corrosion technology, develop closed fuel cycle systems, and accelerate the commercialization process through international standardization cooperation to provide sustainable clean energy solutions for basic load power supply, high-temperature hydrogen production, ship propulsion, and other fields. Full article
(This article belongs to the Special Issue Process Safety Technology for Nuclear Reactors and Power Plants)
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19 pages, 1951 KiB  
Article
FSL-1 Pre-Administration Protects Radiation-Induced Hematopoietic Organs Through the Modulation of the TLR Signaling Pathway
by Venkateshwara Rao Dronamraju, Gregory P. Holmes-Hampton, Emily Gu, Vidya P. Kumar and Sanchita P. Ghosh
Int. J. Mol. Sci. 2025, 26(11), 5303; https://doi.org/10.3390/ijms26115303 - 31 May 2025
Viewed by 510
Abstract
Substantial progress has been made in the development of radiation countermeasures, resulting in the recent approval of several mitigators; however, there has yet to be an approved prophylactic radioprotectant. Research on countermeasure performance in mixed neutron and gamma radiation fields has also been [...] Read more.
Substantial progress has been made in the development of radiation countermeasures, resulting in the recent approval of several mitigators; however, there has yet to be an approved prophylactic radioprotectant. Research on countermeasure performance in mixed neutron and gamma radiation fields has also been scarce. Fibroblast-stimulating lipopeptide (FSL-1) is a novel synthetic agonist for toll-like receptor 2/6. In previous studies, the administration of FSL-1 before and after gamma radiation significantly improved survival outcomes for mice through the activation of the NF-κB pathway. In the current study, we tested FSL-1’s radioprotective abilities in a mixed radiation field that models one produced by a nuclear detonation in 11–14-week-old C57BL/6 male and female mice. We demonstrate that a single dose of 1.5 mg/kg of FSL-1 administered 12 h prior to 65% neutron 35% gamma mixed-field (MF) irradiation enhances survival, accelerates recovery of hematopoietic cell and stem cell populations, reduces inflammation, and protects innate immune function in mice. FSL-1’s ability to recover blood and protect immune functions is important in countering the high rate of incidence of sepsis caused by MF radiation’s damaging effects. These results demonstrate that FSL-1 is a promising prophylactic countermeasure where exposure to MF radiation is anticipated. Full article
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11 pages, 883 KiB  
Article
Rate Equation Analysis of the Effect of Damage Distribution on Defect Evolution in Self-Ion Irradiated Fe
by Toshimasa Yoshiie
Metals 2025, 15(5), 555; https://doi.org/10.3390/met15050555 - 17 May 2025
Viewed by 340
Abstract
Ion irradiations have a damage peak near the beam incident surface. A simulation model with reaction kinetic analysis using rate equations was employed to study the defect evolution caused by localized damage distribution in self-ion irradiated iron. Comparisons were made between the localized [...] Read more.
Ion irradiations have a damage peak near the beam incident surface. A simulation model with reaction kinetic analysis using rate equations was employed to study the defect evolution caused by localized damage distribution in self-ion irradiated iron. Comparisons were made between the localized damage irradiation by ions (the damage peak near the specimen surface) and homogeneous damage irradiation (the flat damage rate across the specimen) such as those caused by neutron irradiation. The irradiation conditions were as follows: the accelerating voltage was 2 MeV and 100 MeV, the irradiation temperatures was 273 K and 573 K, the damage rate was 1 × 10−5 dpa/s, and the total damage was 1 dpa. The distribution of residual point defects in clusters is complex due to the influence of the surface and the sharp distribution of the damage peak. The effects of the damage distributions on defect production were obtained, revealing a dependence on irradiation temperatures. At 573 K irradiation, localized damage irradiation produced higher residual interstitials than homogeneous damage irradiation when using the peak damage rate. The 100 MeV irradiation was more prominent than 2 MeV irradiation. However, the remaining vacancies were almost identical. At 273 K irradiation, the residual point defects, interstitials, and vacancies, were nearly identical in both the localized and homogeneous damage irradiations, even if the accelerating voltage was different. Full article
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17 pages, 4136 KiB  
Article
Simulation Study on Dose and LET of Neutron Irradiation for Biological Experiments Using Spallation, Reactor, and Compact Neutron Sources
by May Sweet, Kenji Mishima, Masahide Harada, Keisuke Kurita, Hiroshi Iikura, Seiji Tasaki and Norio Kikuchi
Quantum Beam Sci. 2025, 9(2), 11; https://doi.org/10.3390/qubs9020011 - 8 Apr 2025
Viewed by 1201
Abstract
Neutron beams, being electrically neutral and highly penetrating, offer unique advantages for the irradiation of biological species such as plants, seeds, and microorganisms. We comprehensively investigated the potential of neutron irradiation for inducing genetic mutations by using simulations of spallation, reactor, and compact [...] Read more.
Neutron beams, being electrically neutral and highly penetrating, offer unique advantages for the irradiation of biological species such as plants, seeds, and microorganisms. We comprehensively investigated the potential of neutron irradiation for inducing genetic mutations by using simulations of spallation, reactor, and compact neutron sources based on J-PARC BL10, the JRR-3 TNRF, and KUANS. We analyzed neutron flux, energy deposition rates, and Linear Energy Transfer (LET) distributions. The KUANS simulation demonstrated the highest dose rate of 17 Gy/h, significantly surpassing that obtained at BL10, due to the large solid angle achieved with optimal sample placement. The findings highlight KUANS’s suitability for efficiently inducing specific genetic mutations and neutron breeding, particularly for inducing targeted mutations in biological samples, also on account of its LET range of 20–70 keV/μm. Our results emphasize the importance of choosing neutron sources based on LET requirements to maximize mutation induction efficiency. This research study shows the potential of compact neutron sources such as KUANS for effective biological irradiation and neutron breeding, offering a viable alternative to larger facilities. The neutron filters used at BL10 and the TNRF effectively exclude low-energy neutrons while keeping the high-LET component. The neutron capture reaction, 14N(n,p)14C, was found to be the main dose contributor under thermal neutron-dominated conditions. Full article
(This article belongs to the Special Issue Quantum Beam Science: Feature Papers 2024)
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17 pages, 3519 KiB  
Article
An Interpretable Dynamic Feature Search Methodology for Accelerating Computational Process of Control Rod Descent in Nuclear Reactors
by Qingyu Huang, Cong Xiao, Wei Zeng, Le Xu, Jia Liu, Zhixin Pang, Yuanfeng Lin, Mengwei Zhao and Xiaobo Liu
Energies 2025, 18(7), 1827; https://doi.org/10.3390/en18071827 - 4 Apr 2025
Viewed by 300
Abstract
Within the operational dynamics of a nuclear reactor, the customary approach involves modulating the reactor’s power output by means of control rod manipulation, which effectively alters the neutron density across the core. The descent behavior of the control rod drive lines pertains to [...] Read more.
Within the operational dynamics of a nuclear reactor, the customary approach involves modulating the reactor’s power output by means of control rod manipulation, which effectively alters the neutron density across the core. The descent behavior of the control rod drive lines pertains to the intricate motion exhibited by the control rod components within the reactor during its operational lifespan, characterized by conditions of heightened irradiation, temperature, pressure, and complex fluid dynamics. The precise calculation of the control rod descent process is an integral facet of reactor structural design to ensure the safe and reliable operation of the reactor. However, the current computational fluid dynamics-based simulation methods employed for this purpose necessitate extensive grid computations, imposing significant computational burdens in terms of resources and time. In light of this challenge, we present a novel and interpretative algorithm rooted in dynamic similarity feature search. Through comprehensive validation, this algorithm demonstrates remarkable precision, with the computational results exhibiting an error margin within 10% while simultaneously achieving a substantial enhancement of computational efficiency of nearly three orders of magnitude when compared to conventional computational fluid dynamics techniques and sequence-to-sequence machine learning algorithms. Notably, this algorithm showcases exceptional versatility, holding immense promise for broad applicability across various operational scenarios encountered during the intricate process of nuclear reactor design. Full article
(This article belongs to the Special Issue Advances in Nuclear Power Plants and Nuclear Safety)
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13 pages, 11263 KiB  
Article
Investigation of Electrical Performance Degradation of β-Ga2O3 Schottky Barrier Diodes Induced by X-Ray and Neutron Irradiation
by Pengfei Zhao, Xu Tan, Weili Fu and Teng Ma
Electronics 2025, 14(7), 1343; https://doi.org/10.3390/electronics14071343 - 27 Mar 2025
Viewed by 463
Abstract
This paper presents a preliminary investigation into the total dose effects and displacement damage effects on β-Ga2O3 Schottky barrier diodes (SBDs) induced by X-rays with an average energy of 8–20 keV and 1 MeV reactor neutrons. The electrical performance [...] Read more.
This paper presents a preliminary investigation into the total dose effects and displacement damage effects on β-Ga2O3 Schottky barrier diodes (SBDs) induced by X-rays with an average energy of 8–20 keV and 1 MeV reactor neutrons. The electrical performance of the devices before and after irradiation was evaluated through direct current (I-V) and capacitance–voltage (C-V) measurements. The results indicate that under X-ray irradiation, as the irradiation fluence increases, the forward current density, leakage current, and reverse current density of the devices increase, suggesting a progressive degradation of device performance with higher irradiation fluence. In the case of neutron irradiation, the forward current density decreases, while the leakage current and reverse current density increase with rising irradiation fluence. By employing techniques such as low-frequency noise (LFN) and deep-level transient spectroscopy (DLTS), changes in defect concentrations before and after irradiation were analyzed. It was found that the primary causes of device performance degradation are the interface defects induced by X-ray irradiation and the increased bulk defect concentration caused by neutron irradiation. These findings were further validated through two-dimensional numerical simulations using TCAD tools, providing significant theoretical insights and experimental data to enhance reliability and optimize the design of such devices. Full article
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22 pages, 5551 KiB  
Article
Primary and Low-Strain Creep Models for 9Cr Tempered Martensitic Steels Including the Effects of Irradiation Softening and High-Helium Re-Hardening
by Md Ershadul Alam, Takuya Yamamoto and George Robert Odette
Metals 2025, 15(4), 354; https://doi.org/10.3390/met15040354 - 24 Mar 2025
Viewed by 485
Abstract
Primary and low-strain creep represents a very important integrity challenge to large, complex structures, like fusion reactors. Here, we develop a predictive empirical primary creep model for 9Cr tempered martensitic steels (TMS), relating the applied stress (σ) to strain (ε), time (t) and [...] Read more.
Primary and low-strain creep represents a very important integrity challenge to large, complex structures, like fusion reactors. Here, we develop a predictive empirical primary creep model for 9Cr tempered martensitic steels (TMS), relating the applied stress (σ) to strain (ε), time (t) and temperature (T). The most accurate model is based on the applied σ normalized by the steel’s T-dependent ultimate tensile stress (σo), σ/σo(T). The model, fit to 17 heats of 9Cr TMS, yielded a σ root mean square error (RMSE) of ≈±11 MPa. Notably, the model also provides robust predictions for all the other TMS, when calibrated only by the fusion candidate Eurofer97 database. The model was extended to explore two possible effects of neutron irradiation, which produces both displacements per atom (dpa) and helium (He in atomic parts per million, appm) damage. These effects, which have not been previously considered, include: (a) softening, as a function of dpa, at T > ≈400–450 °C, in low-He fission environments (<1 He/dpa); and (b) subsequent re-hardening in high-He (≥10 He/dpa) fusion first-wall environments. The irradiation effect models predict (a) accelerated primary creep due to irradiation softening; and (b) fully arrested creep due to high-He re-hardening. Full article
(This article belongs to the Special Issue Manufacture, Properties and Applications of Advanced Nuclear Alloys)
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17 pages, 11771 KiB  
Article
Microstructure of CuCrZrV and ODS(Y2O3)-Cu Alloys After Neutron Irradiation at 150, 350, and 450 °C to 2.5 dpa
by Michael Klimenkov, Carsten Bonnekoh, Ute Jaentsch, Michael Rieth, Hans-Christian Schneider, Dmitry Terentyev, Koray Iroc and Wouter Van Renterghem
Materials 2025, 18(7), 1401; https://doi.org/10.3390/ma18071401 - 21 Mar 2025
Viewed by 406
Abstract
In this study, the results of transmission electron microscopy (TEM) examinations of neutron-irradiated (2.5 dpa at 150 °C, 350 °C, and 450 °C) CuCrZrV and ODS(Y2O3)-Cu alloys are presented. These materials were developed for application as heat sink materials [...] Read more.
In this study, the results of transmission electron microscopy (TEM) examinations of neutron-irradiated (2.5 dpa at 150 °C, 350 °C, and 450 °C) CuCrZrV and ODS(Y2O3)-Cu alloys are presented. These materials were developed for application as heat sink materials in fusion technology. This study includes TEM imaging and quantitative analysis of neutron radiation-induced defects such as dislocation loops and voids as well as the determination of the conditions for their formation. It was found that dislocation loops of a0½⟨110⟩ type form in both alloys at all irradiation temperatures. The formation of voids in CuCrZrV alloy is effectively suppressed. The neutron irradiation causes a redistribution of Cr, Zr, and V in the CuCrZrV alloy. A particular focus was on the investigation of the distribution of the transmutation products Ni and Zn. Ni tends to segregate at the Cr-rich clusters and forms a shell around them, while Zn is evenly distributed. Full article
(This article belongs to the Special Issue Mechanical Behavior and Radiation Response of Materials)
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