Search

Medical radioisotope production using neutron irradiation via fission reaction requires a sufficient neutron source. The Kartini reactor has been proposed and studied to become a neutron source for radioisotope production under the Subcritical Assembly for 99Mo Production (SAMOP) project, which uses uranyl nitrate solution as the irradiation target. A full-scale experiment involving a liquid fission product is difficult to conduct and requires facility rearrangement to reduce the risk of contamination. Although a small-batch experiment is safer to perform, a pre-experimental assessment is necessary to address the practicality of production and the accompanying problems. The goals of this assessment are (1) to characterize the Kartini reactor irradiation facilities' flux through experiment and Monte Carlo benchmark simulation, (2) to predict the irradiation product inventory in relation to the variation of uranium concentration and the measured flux, and (3) to predict the irradiated sample gamma spectrum reading using high-purity germanium detector simulation. The irradiation simulation uses natural uranium as a control parameter, which caused the irradiation inventory dominated by actinides from transmutation. The simulation also presents the possibility of instant small-batch 99Mo production using the measured Lazy Susan facilities' flux from a neutronic perspective. The qualitative assessment of the predicted irradiation inventory and its spectrum reading from different sample concentrations are discussed along with the recommendation and possible action to improve the experiment or future production process. [ABSTRACT FROM AUTHOR]

High strength, high conductivity copper alloys that can resist creep at high temperatures are one of the primary candidates for efficient heat exchangers in fusion reactors. Cu–Cr–Nb–Zr (CCNZ) alloys, which were designed to improve the strength and creep life of ITER Cu–Cr–Zr (CCZ) reference alloys, have been found to have comparable electrical conductivity and tensile properties to CCZ alloys. The measured creep rupture times for these improved alloys is about ten times higher than the ITER reference alloys at 90–125 MPa at 500 °C. However, the effects of neutron irradiation on these alloys, and the ensuing material properties, have not been studied; thus, their utility in a fusion reactor environment is not well understood. This study characterizes the room temperature mechanical and electrical properties of a neutron-irradiated CCNZ alloy and compares them to a neutron-irradiated ITER reference heat sink CCZ alloy. Tensile specimens were neutron irradiated in the High Flux Isotope Reactor (HFIR) to 5 dpa between 250 °C and 325 °C. Post-irradiation characterization included electrical resistivity measurements, hardness, and tensile tests. Microstructural evaluation used scanning electron microscopy, energy dispersive x-ray spectroscopy, and atom probe tomography to characterize the irradiation-produced changes in the microstructure and investigate the mechanistic processes leading to post-irradiation properties. Transmutation calculations were validated with composition measurements from atom probe data and used to calculate contributions to the increased electrical resistivity measured after irradiation. Comparisons with CCZ alloys in the same irradiation heat found that the post-irradiated CCNZ and CCZ alloys had comparable electrical resistivity. Although CCNZ alloys suffered more irradiation hardening than CCZ, the overall tensile behavior deviated very little from non-irradiated values in the temperature range studied. [ABSTRACT FROM AUTHOR]

The current experimental investigation demonstrates the capability of neutron imaging to quantify cavitation, in terms of vapour content, within an orifice of an abruptly constricting geometry. The morphology of different cavitation regimes setting in was properly visualised owing to the high spatial resolution of 16 μm achieved, given the extensive field of view of 12.9 × 12.9 mm2 offered by the imaging set-up. At a second step, the method was proven capable of highlighting subtle differences between fluids of different rheological properties. More specifically, a reference liquid was comparatively assessed against a counterpart additised with a Quaternary Ammonium Salt (QAS) agent, thus obtaining a viscoelastic behaviour. In accordance with previous studies, it was verified, yet in a quantifiable manner, that the presence of viscoelastic additives affects the overall cavitation topology by promoting the formation of more localised vortical cavities rather than cloud-like structures occupying a larger portion of the orifice core. To the authors' best knowledge, the present work is the first to demonstrate that neutron imaging is suitable for quantifying in-nozzle cavitating flow at the micrometre level, consequently elucidating the distinct forms of vaporous structures that arise. The potential of incorporating neutron irradiation for the quantification of two-phase flows in metallic microfluidics devices has been established. [ABSTRACT FROM AUTHOR]

The fast component (0.7–18 MeV) of the neutron spectrum at the Pneumatic Fast Transfer System (PFTS) in the KAMINI reactor was determined by irradiating threshold activation foils. The acquired reaction rates are subsequently unfolded using SAND-II code. The KAMINI reactor was modelled in the MCNP-4B code for an estimate of neutron spectrum at the PFTS location, which was subsequently used as the initial apriori solution for the SAND-II code. The unfolded fast component spectrum at the PFTS was found to be similar to that of the fast benchmark GODIVA and JEZEBEL-23. Moreover, the investigation is substantiated by incorporating modified spectra to estimate the theoretical yield of radioisotopes 32P at PFTS using a Monte Carlo simulation against its experimental yield. The results agree with an accuracy of 6%, affirming the credibility of the derived spectrum. Theoretical yields of 89Sr, 64Cu, and 47Sc were also estimated at the same location. [ABSTRACT FROM AUTHOR]

We have proposed to produce a 229Th/225Ac generator by neutron irradiation of the 228Ra target, which is a decay product from 232Th. The solutions containing 232Th and 228Ra were obtained through the thermal chemical conversion method to dissolve the ThO2. Then, the separation of 228Ra from thorium solutions through co-precipitation with magnesium was studied. It was confirmed that radium is coprecipitated by this method. It was also confirmed that the precipitated magnesium carbonate can be easily converted to magnesium oxide. The decontamination of thorium from precipitated radium was investigated, and it was found that a rough decontamination of thorium was achieved by co-precipitation methods. The decontamination of thorium depends on the chemical conversion conditions and the dissolution methods used. [ABSTRACT FROM AUTHOR]

ITER is of key importance in the European fusion roadmap as it aims to prove the scientific and technological feasibility of fusion as a future energy source. The EUROfusion consortium of labs within Europe is contributing to the preparation of ITER scientific exploitation and operation and aspires to exploit ITER outcomes in view of DEMO. The paper provides an overview of the major progress obtained recently, carried out in the frame of the new (initiated in 2021) EUROfusion work-package called ' Pr eparation of I TER O peration' (PrIO). The overview paper is directly supported by the eleven EUROfusion PrIO contributions given at the 29th Fusion Energy Conference (16–21 October 2023) London, UK [www.iaea.org/events/fec2023]. The paper covers the following topics: (i) development and validation of tools in support to ITER operation (plasma breakdown/burn-through with evolving plasma volume, new infra-red synthetic diagnostic for off-line analysis and wall monitoring using Artificial Intelligence techniques, synthetic diagnostics development, development and exploitation of multi-machine databases); (ii) R&D for the radio-frequency ITER neutral beam sources leading to long duration of negative deuterium/hydrogen ions current extraction at ELISE and participation in the neutral beam test facility with progress on the ITER source SPIDER, and, the commissioning of the 1 MV high voltage accelerator (MITICA) with lessons learned for ITER; (iii) validation of neutronic tools for ITER nuclear operation following the second JET deuterium–tritium experimental campaigns carried out in 2021 and in 2023 (neutron streaming and shutdown dose rate calculation, water activation and activated corrosion products with advanced fluid dynamic simulation; irradiation of several materials under 14.1 MeV neutron flux etc). [ABSTRACT FROM AUTHOR]

The Spherical Tokamak for Energy Production (STEP) requires high-field magnet designs and has therefore adopted the REBCO-based high-temperature superconductor (HTS) as its current carrier. The HTS enables the toroidal field (TF) coils to be remountable, which unlocks STEP's vertical maintenance approach; however, remountable joints, approximately 18 GJ of stored energy and limited space down the centre of a spherical tokamak, make the TF coils the most challenging. STEP has pursued a passive approach to TF coil quench protection in order to limit coil terminal voltage. Initial results suggest that a solution may rely on tuning internal coil resistance coupled with actively powered heaters. The pre-conceptual inter-coil structure demonstrates acceptable stresses and deflections under steady-state operating conditions and preliminary fault scenarios, and loads are distributed to limit the tensile force on the TF centre rod. Finally, the HTS must operate reliably in a high radiation environment and endure high neutron fluences, ensuring commercially relevant magnet lifetimes. Initial experiments indicate that instantaneous gamma irradiation of HTS has no negative impact on current carrying capacity. Experimental programmes are underway to cold irradiate HTS to fusion-relevant fluences and to develop a method of assuring tape irradiation tolerance using oxygen ions as an analogue for neutrons. This article is part of the theme issue 'Delivering Fusion Energy – The Spherical Tokamak for Energy Production (STEP)'. [ABSTRACT FROM AUTHOR]

In recent years, various drug delivery systems circumventing the blood–brain barrier have emerged for treating brain tumors. This study aimed to improve the efficacy of brain tumor treatment in boron neutron capture therapy (BNCT) using cerebrospinal fluid (CSF) circulation to deliver boronophenylalanine (BPA) to targeted tumors. Previous experiments have demonstrated that boron accumulation in the brain cells of normal rats remains comparable to that after intravenous (IV) administration, despite BPA being administered via CSF at significantly lower doses (approximately 1/90 of IV doses). Based on these findings, BNCT was conducted on glioma model rats at the Kyoto University Research Reactor Institute (KUR), with BPA administered via CSF. This method involved implanting C6 cells into the brains of 8-week-old Wistar rats, followed by administering BPA and neutron irradiation after a 10-day period. In this study, the rats were divided into four groups: one receiving CSF administration, another receiving IV administration, and two control groups without BPA administration, with one subjected to neutron irradiation and the other not. In the CSF administration group, BPA was infused from the cisterna magna at 8 mg/kg/h for 2 h, while in the IV administration group, BPA was intravenously administered at 350 mg/kg via the tail vein over 1.5 h. Thermal neutron irradiation (5 MW) for 20 min, with an average fluence of 3.8 × 1012/cm2, was conducted at KUR's heavy water neutron irradiation facility. Subsequently, all of the rats were monitored under identical conditions for 7 days, with pre- and post-irradiation tumor size assessed through MRI and pathological examination. The results indicate a remarkable therapeutic efficacy in both BPA-administered groups (CSF and IV). Notably, the rats treated with CSF administration exhibited diminished BPA accumulation in normal tissue compared to those treated with IV administration, alongside maintaining excellent overall health. Thus, CSF-based BPA administration holds promise as a novel drug delivery mechanism in BNCT. [ABSTRACT FROM AUTHOR]

We present a first-principles-based electron-temperature model that can be used in atomistic calculations. The electron–phonon coupling coefficient in the model is derived from the density of states as a function of electron temperature, and the thermal conductivity of tungsten from our model shows significant improvement over the baseline atomistic calculations in which only ion-thermal contribution to the thermal conductivity is available. The correction to the thermal conductivity also changes damage cascades as cascades cool down more rapidly within our model. The mobility of defects is consequently reduced, leaving more residual damage than the predictions without an electron-temperature model. [ABSTRACT FROM AUTHOR]

Neutron and γ-ray irradiation damages to transistors are found to be non-additive, and this is denoted as the irradiation synergistic effect (ISE). Its mechanism is not well-understood. The recent defect-based model [Song and Wei, ACS Appl. Electron. Mater. 2, 3783 (2020)] for silicon bipolar junction transistors (BJTs) achieves quantitative agreement with experiments, but its assumptions on the defect reactions are unverified. Going beyond the model requires directly representing the effect of γ-ray irradiation in first-principles calculations, which was not feasible previously. In this work, we examine the defect-based model of the ISE by developing a multiscale method for the simulation of the γ-ray irradiation, where the γ-ray-induced electronic excitations are treated explicitly in excited-state first-principles calculations. We find the calculations agree with experiments, and the effect of the γ-ray-induced excitation is significantly different from the effects of defect charge state and temperature. We propose a diffusion-based qualitative explanation of the mechanism of positive/negative ISE in NPN/PNP BJTs in the end. [ABSTRACT FROM AUTHOR]

Radiation-induced property changes in materials originate from the energy transfer from an incoming particle to the existing lattice, displacing atoms. The displaced atoms can cause the formation of extended defects including dislocation loops, voids, or precipitates. The non-equilibrium defects created during damage events determine the extent of these larger defects and are a function of dose rate, material, and temperature. However, these defects are transient and can only be probed indirectly. This work presents direct experimental measurements and evidence of irradiated non-equilibrium vacancy formation, where in situ positron annihilation spectroscopy was used to prove the generation of non-equilibrium defects in silicon. [ABSTRACT FROM AUTHOR]

As a key material of nuclear power plant, the safe service of reactor cavity concrete is one of the prerequisites for the long-term stable and safe operation of nuclear power plant. In order to study the neutron irradiation damage mechanism of the reactor cavity concrete, obtain the test data of the reactor cavity concrete in the neutron irradiation environment, and provide a scientific basis for the long-term stable operation of the nuclear power unit, the irradiation test method of the reactor cavity concrete was established, and the irradiation test device with a water-passing basket structure was developed in this paper. The physical and thermal design of the irradiation test of the reactor cavity concrete was carried out with the numerical calculation method. The accelerated neutron irradiation test of the reactor cavity concrete was carried out in the 5# hole with a pressure tube in Minjiang Test Reactor (MJTR) by using the irradiation pile method with the reactor. The standard concrete samples of 50 mm×50 mm and the small concrete samples of 25 mm×25 mm were loaded in the cavity of the irradiation test section for the irradiation test device, and seven layers were arranged axially in the 1 000 mm active area of the reactor. During the irradiation test, the pressure tube was filled with the deionized water, and the concrete sample was directly in contact with the deionized water. The neutron flux and the irradiation test temperature were measured by the neutron detector and the thermocouple respectively. The irradiation test results show that the irradiation test method is feasible, the irradiation test device is reasonable, and the neutron irradiation of multiple concrete standard samples and small samples is realized. The cumulative fast neutron flux of the concrete sample (E≥0.1 MeV) is distributed in 2.38×1018-2.06×1018 cm−2, the temperature of the irradiation test is stable during 50-60 ℃, and the irradiation test index meets the test requirements. Furthermore, the appearance inspection, size measurement and ballast test of the standard and small concrete samples before and after irradiation were carried out. The results show that compared with before irradiation, there is no obvious difference in the external shape of concrete samples, but the color of concrete samples changes greatly, the overall color of concrete samples is yellow-gray after irradiation, and the outer size of concrete samples has a certain increase. Therefore, under the irradiation condition of average fast neutron flux of 3.41×1018 cm−2, there are certain irradiation swelling and mechanical performance degradation phenomenon of the reactor cavity concrete.

Boron Neutron Capture Therapy (BNCT) is performed using high-intensity neutron sources; however, the energy of the primary neutrons is too high for direct patient irradiation. Thus, neutron moderation is mandatory and is performed using a device known as a Beam Shaping Assembly (BSA). Due to the differences in flux and energy spectra between neutron sources, each facility needs a dedicated BSA design, whether it is based on a nuclear reactor or, more recently, on an accelerator. Since moderation involves the loss of neutrons, typically by a factor of 1000, it is necessary to generate a very high flux before neutrons pass through the BSA. We propose a novel approach that eliminates the necessity of a BSA, BSA-free, by generating neutrons suitable in flux and energy for direct patient irradiation through the Sc(p,n) Ti reaction using near-threshold protons. Our findings demonstrate that all IAEA quality factors for BNCT can be met with existing proton accelerators. Additionally, figures of merit studied provide similar results compared to real BNCT facilities. This breakthrough opens up new avenues in BNCT, among others, the control of the neutron penetration within the human body by small changing in the proton energy. Also, it is expected simplified accelerator-based facilities in terms of manufacturing and maintenance and operation. This work is a study based on experimental data and Monte Carlo simulations. Technical challenges and safety are addressed in Discussion section. This novel proposal is under evaluation as patent. [ABSTRACT FROM AUTHOR]

The breeding of disease-resistant soybeans cultivars to manage Phytophthora root and stem rot caused by the pathogen Phytophthora sojae involves combining quantitative disease resistance (QDR) and Rps gene-mediated resistance. To identify and confirm potential mechanisms of QDR toward P. sojae, we conducted a time course study comparing changes in gene expression among Conrad and M92-220 with high QDR to susceptible genotypes, Sloan, and three mutants derived from fast neutron irradiation of M92-220. Differentially expressed genes from Conrad and M92-220 indicated several shared defense-related pathways at the transcriptomic level but also defense pathways unique to each cultivar, such as stilbenoid, diarylheptanoid, and gingerol biosynthesis and monobactam biosynthesis. Gene Ontology pathway analysis showed that the susceptible fast neutron mutants lacked enrichment of three terpenoid-related pathways and two cell wall-related pathways at either one or both time points, in contrast to M92-220. The susceptible mutants also lacked enrichment of potentially important Kyoto Encyclopedia of Genes and Genomes pathways at either one or both time points, including sesquiterpenoid and triterpenoid biosynthesis; thiamine metabolism; arachidonic acid; stilbenoid, diarylheptanoid, and gingerol biosynthesis; and monobactam biosynthesis. Additionally, 31 genes that were differentially expressed in M92-220 following P. sojae infection were not expressed in the mutants. These 31 genes have annotations related to unknown proteins; valine, leucine, and isoleucine biosynthesis; and protein and lipid metabolic processes. The results of this study confirm previously proposed mechanisms of QDR, provide evidence for potential novel QDR pathways in M92-220, and further our understanding of the complex network associated with QDR mechanisms in soybean toward P. sojae. [ABSTRACT FROM AUTHOR]

With a suitable half-life and abundant radiolabeling strategy, 225Ac has become one of the most promising radionuclides in the area of targeted alpha therapy. However, limited radionuclide supply is threatening the development of 225Ac related endoradiotherapy dramatically. As the parent nuclide of 225Ac, 229Th can be produced via 226Ra(3n, 2ß)229Th reaction in a nuclear reactor. However, related practice has not been conducted in large scale, since the nuclear reaction pathway for producing 229Th is complicated. In this work, the feasibility of producing 225Ac/229Th in a reactor was confirmed by systematic theoretical calculations, and a procedure that combines irradiation with separation process was proposed. The results show that 176 MBq of 229Th can be produced by irradiating 1.0 g of 226Ra with a neutron flux density of 1 × 1015 n cm-2 s1 for 90 days. This will generate 150 MBq of 225Ac monthly from a radionuclide generator, which is sufficient for the single treatment cycle of 200 patients each year considering the radioactivity loss in radiochemical separation, transfer and radiolabeling process. In addition, this irradiation process will also produce 37.8 GBq 227Ac for the preparation of 227Ac-227Th-223Ra generator. In general, the production of 225Ac by neutron irradiation of 226Ra in reactor is practicable and holds potential to alleviate the shortage of current supply of 225Ac. [ABSTRACT FROM AUTHOR]

Neutron irradiation causes embrittlement of reactor pressure vessel (RPV) steels. Post-irradiation annealing is capable of partly or fully restoring the unembrittled condition. While annealing at high temperatures (e.g., 475°C) was successfully applied to extend the lifetime of operating VVER-440 reactors, the benefit of annealing at lower temperatures (e.g., 343°C-the maximum to which the primary cooling water can be heated) is a matter of debate. In this study, neutron-irradiated VVER-440 RPV base metal and weld were exposed to isothermal annealing at 343°C up to 2,000 h. Given the limited amount of material, the degree of recovery was estimated in terms of Vickers hardness, the ductile-brittle transition temperature derived from small punch tests, and the master curve reference temperature derived from fracture mechanics tests of mini samples. For the base metal, small-angle neutron scattering was applied to underpin the findings at the nm-scale. We have found significant partial recovery in both materials after annealing for 300 h or longer. The variations of the degree of recovery are critically discussed and put into the context of wet annealing. [ABSTRACT FROM AUTHOR]

The Two-Photon Absorption–Transient Current Technique (TPA-TCT) is a device characterisation technique that enables three-dimensional spatial resolution. Laser light in the quadratic absorption regime is employed to generate excess charge carriers only in a small volume around the focal spot. The drift of the excess charge carriers is studied to obtain information about the device under test. Neutron-, proton-, and gamma-irradiated p-type pad silicon detectors up to equivalent fluences of about 7 × 1015  n eq / c m 2 and a dose of 186   M r a d are investigated to study irradiation-induced effects on the TPA-TCT. Neutron and proton irradiation lead to additional linear absorption, which does not occur in gamma-irradiated detectors. The additional absorption is related to cluster damage, and the absorption scales according to the non-ionising energy loss. The influence of irradiation on the two-photon absorption coefficient is investigated, as well as potential laser beam depletion by the irradiation-induced linear absorption. Further, the electric field in neutron- and proton-irradiated pad detectors at an equivalent fluence of about 7 × 1015  n eq / c m 2 is investigated, where the space charge of the proton-irradiated devices appears inverted compared to the neutron-irradiated device. [ABSTRACT FROM AUTHOR]

This article provides a comprehensive overview of the Nobel Prizes in Chemistry related to computational chemistry. It explores the history and development of the field, highlighting the contributions of notable scientists and their groundbreaking work in areas such as chemical dynamics, molecular structure, and electronic structure calculations. The article also discusses the Nobel Prizes awarded in specific years, recognizing the achievements of laureates and their significant research contributions. It acknowledges the underrepresentation of women in Nobel Prizes and reflects on the author's personal experiences and hopes for the future of computational chemistry. [Extracted from the article]

Irradiation of CeO 2 with heavy ions is commonly used to accelerate the evaluation of the irradiation performance of UO 2 nuclear fuel. However, the differences in damage rates between ions and neutrons have led to doubts about this method, making it especially important to study the dose rate effect. Here, two kinds of dose rates were used to in-situ irradiate CeO 2 using 400 keV Kr+ at 550 °C and 700 °C to study the dose rate effect on loop characteristics. High dose rate (HR) led to low-density and small-sized dislocation loops compared to low dose rate (LR), which was attributed to the initial high concentration of oxygen vacancies and enhanced recombination of point defects. HR was found to promote the direct nucleation of perfect dislocation loops (PDLs), while under LR irradiation, the PDLs tended to be formed by the transformation of Frank dislocation loops (FDLs) through a typical unfaulting. At a same dose, the proportion of PDL under the HR condition was much higher than that under the LR condition. Temperature greatly affected the loop characteristics. High temperature caused large-sized and small dense loops, as well as high PDL proportion. Moreover, the newly nucleated PDL tended to be close to the pre-existing PDLs and had the same Burgers vector as the adjacent PDL under HR irradiation at 700 °C. Current results provide underlying insights for assessing the effect of dose rate on irradiation-induced loop evolution and a reference for understanding the dose rate effect. [ABSTRACT FROM AUTHOR]

The neutron activation of stable isotopes in environmental matrices, such as soil and groundwater, is a critical aspect of assessing the impact of radionuclide production facilities on the surrounding ecosystem. The envisioned Low-Energy Radioactive Ion Beams (LERIB) facility at the iThemba LABS, South Africa is anticipated to generate significant sources of ionising radiation. The study investigated the possible repercussions of neutron irradiation stemming from the facility, focusing on the activation of stable isotopic compositions in the environment. The investigation employed a combination of experimental and analytical techniques to characterize the neutron activation products in soil and groundwater samples collected from the vicinity. Samples were collected from designated areas for background radiological measurements and were irradiated with neutrons for a period of 1 h. The induced radioactivity measured by the High Purity Germanium detector included 24Na, 22Na, 54Mn, 52Mn, and 46Sc. The application of Darcy’s law for groundwater velocity suggests that radionuclides in groundwater will migrate at an average flow velocity of 0.8 m/day. The isotopes with longer half-lives have count rates at background concentrations; therefore, environmental impacts on the site and surrounding communities might be minimal. [ABSTRACT FROM AUTHOR]

Fuel retention in plasma-facing components (PFCs) is a critical issue in future nuclear fusion reactors operating with Deuterium-Tritium (DT) regarding nuclear safety and fulfillment of the T cycle. However, during DT plasma operation, highly energetic neutrons will induce damage in the lattice of W PFCs causing enhanced fuel retention in defects or traps. Laser-Induced Breakdown Spectroscopy (LIBS) is a potential tool to monitor the T-content in situ in PFCs of future nuclear fusion devices. This article presents an ex situ study on pre-damaged W material after D plasma exposure to qualify the method and mimic conditions expected in a reactor. ITER grade W samples were displacement-damaged by 10.8 MeV W ions to a damage dose of 0.23 dpa and exposed to low temperature deuterium plasma at low energy in PlaQ. The resulting deuterium concentration was analyzed by using 3He Nuclear Reaction Analysis (depth resolution of ≈ 150 nm) as a well-established method, and LIBS (picosecond laser pulses, depth resolution of 15 nm). The sample with the highest deuterium concentration showed a deuterium-rich zone up to a depth of 1.13 μm using both techniques. This is close to the expected W ion-induced damage depth of ≈ 1 μm. The results imply that LIBS as an in situ technique for tritium monitoring could be a viable option for a reactor. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The nature and type of defects formed due to heavy-ion irradiation in tungsten foils are analyzed using transmission electron microscopy. The recrystallized tungsten foils were irradiated by 80 MeV gold ions at room temperature for a fluence of 1.3 × 10 14 ions/cm 2 that amounts to a net displacement per atom (dpa) of 0.22. The defect structures were analyzed using bright-field and weak-beam dark field imaging at two different depths to understand the depth profile of the defects. It is found that the defect clusters formed during the irradiation, both at the near-surface and at 2 μ m depth are of vacancy type that is confirmed by the local strain analysis and supports the findings of vacancy clusters in positron lifetime measurements. The analysis also shows that the dislocation-lines were of pure edge, pure screw and mixed. The fraction of mixed dislocation is found to increase during irradiation at the expense of pure edge and screw dislocations. [ABSTRACT FROM AUTHOR]

High-performance structural materials (HPSMs) are needed for the successful and safe design of fission and fusion reactors. Their operation is associated with unprecedented fluxes of high-energy neutrons and thermomechanical loadings. In fission reactors, HPSMs are used, e.g., for fuel claddings, core internal structural components and reactor pressure vessels. Even stronger requirements are expected for fourth-generation supercritical water fission reactors, with a particular focus on the HPSM's corrosion resistance. The first wall and blanket structural materials in fusion reactors are subjected not only to high energy neutron irradiation, but also to strong mechanical, heat and electromagnetic loadings. This paper presents a historical and state-of-the-art summary focused on the properties and application potential of irradiation-resistant alloys predominantly strengthened by an oxide dispersion. These alloys are categorized according to their matrix as ferritic, ferritic–martensitic and austenitic. Low void swelling, high-temperature He embrittlement, thermal and irradiation hardening and creep are typical phenomena most usually studied in ferritic and ferritic martensitic oxide dispersion strengthened (ODS) alloys. In contrast, austenitic ODS alloys exhibit an increased corrosion and oxidation resistance and a higher creep resistance at elevated temperatures. This is why the advantages and drawbacks of each matrix-type ODS are discussed in this paper. [ABSTRACT FROM AUTHOR]

Microalgae are considered to be more useful and effective to use in biomass production than other photosynthesis organisms. However, microalgae need to be altered to acquire more desirable traits for the relevant purpose. Although neutron radiation is known to induce DNA mutations, there have been few studies on its application to microalgae, and the optimal relationship between irradiation intensity and mutation occurrence has not been established. In this study, using the unicellular red alga Cyanidioschyzon merolae as a model, we analyzed the relationship between the absorbed dose of two types of neutrons, high-energy (above 1 MeV) and thermal (around 25 meV) neutrons, and mutation occurrence while monitoring mutations in URA5.3 gene encoding UMP synthase. As a result, the highest mutational occurrence was observed when the cells were irradiated with 20 Gy of high-energy neutrons and 13 Gy of thermal neutrons. Using these optimal neutron irradiation conditions, we next attempted to improve the lipid accumulation of Euglena gracilis, which is a candidate strain for biofuel feedstock production. As a result, we obtained several strains with a maximum 1.3-fold increase in lipid accumulation compared with the wild-type. These results indicate that microalgae breeding by neutron irradiation is effective. [ABSTRACT FROM AUTHOR]

In this work, the effect of the action of gamma quanta and neutrons on the magnetic properties of Ta/feromagnet/IrMn/Ta bilayer films with an exchange bias of the hysteresis loop is studied. The samples were fabricated by magnetron sputtering, and their structure was studied by small-angle X-ray reflectometry and X-ray diffractometry. The measurement of the magnetic hysteresis loops of the irradiated and non-irradiated samples was carried out by the methods of magneto-optical Kerr magnetometry. As a result, the effect of broadening of the magnetic hysteresis loop after irradiation was found. The maximum broadening of the hysteresis loop was observed in the NiFe/IrMn film under neutron irradiation; in this case, the loop width increased by more than 2.5 times. No noticeable change in the field of the exchange bias of the hysteresis loops was observed in the entire range of radiation exposure. [ABSTRACT FROM AUTHOR]

Background: Cyclotron‐based proton therapy systems utilize the highest proton energies to achieve an ultra‐high dose rate (UHDR) for FLASH radiotherapy. The deep‐penetrating range associated with this high energy can be modulated by inserting a uniform plate of proton‐stopping material, known as a range shifter, in the beam path at the nozzle to bring the Bragg peak within the target while ensuring high proton transport efficiency for UHDR. Aluminum has been recently proposed as a range shifter material mainly due to its high compactness and its mechanical properties. A possible drawback lies in the fact that aluminum has a larger cross‐section of producing secondary neutrons compared to conventional plastic range shifters. Accordingly, an increase in secondary neutron contamination was expected during the delivery of range‐modulated FLASH proton therapy, potentially heightening neutron‐induced carcinogenic risks to the patient. Purpose: We conducted neutron dosimetry using simulations and measurements to evaluate excess dose due to neutron exposure during UHDR proton irradiation with aluminum range shifters compared to plastic range shifters. Methods: Monte Carlo simulations in TOPAS were performed to investigate the secondary neutron production characteristics with aluminum range shifter during 225 MeV single‐spot proton irradiation. The computational results were validated against measurements with a pair of ionization chambers in an out‐of‐field region (≤$\le$ 30 cm) and with a Proton Recoil Scintillator‐Los Alamos rem meter in a far‐out‐of‐field region (0.5–2.5 m). The assessments were repeated with solid water slabs as a surrogate for the conventional range shifter material to evaluate the impact of aluminum on neutron yield. The results were compared with the International Electrotechnical Commission (IEC) standards to evaluate the clinical acceptance of the secondary neutron yield. Results: For a range modulation up to 26 cm in water, the maximum simulated and measured values of out‐of‐field secondary neutron dose equivalent per therapeutic dose with aluminum range shifter were found to be (0.57±0.02)mSv/Gy$(0.57\pm 0.02)\ \text{mSv/Gy}$ and (0.46±0.04)mSv/Gy$(0.46\pm 0.04)\ \text{mSv/Gy}$, respectively, overall higher than the solid water cases (simulation: (0.332±0.003)mSv/Gy$(0.332\pm 0.003)\ \text{mSv/Gy}$; measurement: (0.33±0.03)mSv/Gy$(0.33\pm 0.03)\ \text{mSv/Gy}$). The maximum far out‐of‐field secondary neutron dose equivalent was found to be (8.8±0.5$8.8 \pm 0.5$) μSv/Gy$\umu {\rm Sv/Gy}$ and (1.62±0.02$1.62 \pm 0.02$) μSv/Gy$\umu {\rm Sv/Gy}$ for the simulations and rem meter measurements, respectively, also higher than the solid water counterparts (simulation: (3.3±0.3$3.3 \pm 0.3$) μSv/Gy$\umu {\rm Sv/Gy}$; measurement: (0.63±0.03$0.63 \pm 0.03$) μSv/Gy$\umu {\rm Sv/Gy}$). Conclusions: We conducted simulations and measurements of secondary neutron production under proton irradiation at FLASH energy with range shifters. We found that the secondary neutron yield increased when using aluminum range shifters compared to conventional materials while remaining well below the non‐primary radiation limit constrained by the IEC regulations. [ABSTRACT FROM AUTHOR]

The study reports the significance of carbon presence in affecting void nucleation in Fe. Without carbon, void nucleation rates decrease gradually at high temperatures but remain significantly high and almost saturated at low temperatures. With carbon present, even at 1 atomic parts per million, void nucleation rates show a low-temperature cutoff. With higher carbon levels, the nucleation temperature window becomes narrower, the maximum nucleation rate becomes lower, and the temperature of maximum void nucleation shifts to a higher temperature. Fundamentally, this is caused by the change in effective vacancy diffusivity due to the formation of carbon-vacancy complexes. The high sensitivity of void nucleation to carbon comes from the high sensitivity of void nucleation to the vacancy arrival rate in a void. The void nucleation is calculated by first obtaining the effective vacancy diffusivity considering the carbon effect, then calculating the defect concentration and defect flux change considering both carbon effects and pre-existing dislocations, and finally calculating the void nucleation rate based on the recently corrected homogeneous void nucleation theory. The study is important not only in the fundamental understanding of impurity effects in ion/neutron irradiation but also in alloy engineering for judiciously introducing impurities to increase swelling resistance, as well as in the development of simulation and modeling methodologies applicable to other metals. [ABSTRACT FROM AUTHOR]

Exposure of metals to neutron irradiation results in an increase in the yield strength and a significant loss of ductility. Irradiation hardening is also closely related to the fracture toughness temperature shift or the ductile-to-brittle transition temperature (DBTT) shift in alloys with a body-centered cubic (bcc) crystal structure. Ion irradiation is an indispensable tool in the study of the radiation effects of materials for nuclear energy systems. Due to the shallow damage depth in ion-irradiated materials, the nanoindentation test is the most commonly used method for characterizing the changes in mechanical properties after ion irradiation. Issues that affect the analysis of irradiation hardening may arise due to changes in the surface morphology and mechanical properties, as well as the inherent complexities in nanoscale indentation. These issues, including changes in surface roughness, carbon contamination, the pile-up effect, and the indentation size effect, with corresponding measures, were reviewed. Modeling using the crystal plasticity finite element method of the nanoindentation of ion-irradiated materials was also reviewed. The challenges in extending the nanoindentation test to high temperatures and to multiscale simulation were addressed. [ABSTRACT FROM AUTHOR]

Studying temperature effects on defect behaviors during thermal annealing is significant for understanding the performance degradation and recovery of semiconductor devices under irradiation. We systematically studied temperature effects on annealing crucial deep-level defects in neutron-irradiated silicon, by developing a multiscale modeling approach. The temperature-dependent concentrations and electron occupation ratios of crucial defects of divacancies (V2) and tri-vacancies (V3) were given for dynamic and post-irradiation annealing. Besides the common direct dissociation, we found a new approach to eliminating V2 and V3 by their recombination with interstitials dissociated from interstitial-relative defects at relatively low temperatures. To effectively eliminate V2 and V3 by post-irradiation annealing, we further determined the activation energies of 1.98eV and 1.71eV for V2 and V3, respectively. We also found that, within the operation temperature range of devices, the higher the temperature, the better the radiation resistance. It is thus recommended that the optimal temperature of post-irradiation annealing for device performance recovery is near 600K. [ABSTRACT FROM AUTHOR]

We developed a Zr two-photon resonance ionization scheme with a high useful yield of 6.3(5)%. This scheme utilizes the known intermediate energy level at 26443.88 cm−1 and a newly characterized Rydberg level at 53490.79(26) cm−1. Both the first (378.16 nm) and second (369.727 nm) transition wavelengths are accessible by frequency-doubled titanium:Sapphire lasers. We utilize the new scheme to analyze the isotopics of Zr, a fission product, in micrometer-sized spent nuclear fuel samples to understand their irradiation history. This includes the dependence on burnup and radial location within a fuel pellet. Resonance ionization mass spectrometry was used to obtain almost isobar-free Zr isotopic ratios from seven samples. The measured isotopic ratios from the spent nuclear fuel show a strong dependence on radial position within the fuel pellet while the effect of average pellet burnup was much less pronounced. All Zr isotopic ratios systematically change from the pellet center to the pellet edge, where isotopic values are close to those expected from 235U fission and 239Pu fission, respectively. Using Zr isotopics, we demonstrate a potential method to distinguish between samples derived from the edge or center of a fuel element of unknown pedigree, which strongly impacts the interpretation of a sample's irradiation history as the neutron fields are different between these locations. [ABSTRACT FROM AUTHOR]

In boron neutron capture therapy (BNCT), boron drugs should exhibit high intratumoral boron concentrations during neutron irradiation, while being cleared from the blood and normal organs. However, it is usually challenging to achieve such tumor accumulation and quick clearance simultaneously in a temporally controlled manner. Here, we developed a polymer-drug conjugate that can actively control the clearance of the drugs from the blood. This polymer-drug conjugate is based on a biocompatible polymer that passively accumulates in tumors. Its side chains were conjugated with the low-molecular-weight boron drugs, which are immediately excreted by the kidneys, via photolabile linkers. In a murine subcutaneous tumor model, the polymer-drug conjugate could accumulate in the tumor with the high boron concentration ratio of the tumor to the surrounding normal tissue (∼10) after intravenous injection while a considerable amount remained in the bloodstream as well. Photoirradiation to blood vessels through the skin surface cleaved the linker to release the boron drug in the blood, allowing for its rapid clearance from the bloodstream. Meanwhile, the boron concentration in the tumor which was not photoirradiated could be maintained high, permitting strong BNCT effects. In clinical BNCT, the dose of thermal neutrons to solid tumors is determined by the maximum radiation exposure to normal organs. Thus, our polymer-drug conjugate may enable us to increase the therapeutic radiation dose to tumors in such a practical situation. [Display omitted] • Pharmacokinetics was actively controlled in a light-responsive manner. • Our system could achieve the high tumor accumulation and T/B ratio simultaneously. • The active control of pharmacokinetics augmented BNCT effects. [ABSTRACT FROM AUTHOR]

KAlpakkam MINI reactor (KAMINI) is a 233U fuelled research reactor has various neutron irradiation locations for experimental purposes. The pit at the south beam end of KAMINI reactor is being extensively utilised for neutron attenuation experiments in prospective shielding materials as well as for neutron radiography. During reactor operation, it will be closed by a movable shield. A vault door is located above the shield and the movable shield is used to attenuate streaming neutrons and gamma-rays during reactor operation. Even with the shield, there exists significant dose because of streaming neutrons and gamma rays. Its variation depends on the power of the reactor. The neutron and gamma dose rates close to the south beam vault door have recently been found to be 275–300 μSv/h and 175–200 μSv/h, respectively, when the reactor is operating at 10 kW. In order to characterise the streaming neutron spectra of vault door place for the first time, measurements are done using the Nested Neutron Spectrometer. Along with the neutron flux, neutron mean energy and ambient dose-equivalent rate are also measured and compared with earlier measurements carried out inside the south beam pit. It is observed that the presence of paraffin shield reduces the neutron average energy from 370 to 178 keV. Apart from energy reduction, 10 kW normalised neutron flux of south beam pit is also attenuated by the shield by 25 000 times and it is found that the neutron spectrum of the measured location is also more thermalized. Neutron reference data of the location are generated. [ABSTRACT FROM AUTHOR]

In the next decade, the International Commission on Radiological Protection (ICRP) will issue the next set of general recommendations, for which evaluation of relative biological effectiveness (RBE) for various types of tissue reactions would be needed. ICRP has recently classified diseases of the circulatory system (DCS) as a tissue reaction, but has not recommended RBE for DCS. We therefore evaluated the mean and uncertainty of RBE for DCS by applying a microdosimetric kinetic model specialized for RBE estimation of tissue reactions. For this purpose, we analyzed several RBE data for DCS determined by past animal experiments and evaluated the radius of the subnuclear domain best fit to each experiment as a single free parameter included in the model. Our analysis suggested that RBE for DCS tends to be lower than that for skin reactions, and their difference was borderline significant due to large variances of the evaluated parameters. We also found that RBE for DCS following mono-energetic neutron irradiation of the human body is much lower than that for skin reactions, particularly at the thermal energy and around 1 MeV. This tendency is considered attributable not only to the intrinsic difference of neutron RBE between skin reactions and DCS but also to the difference in the contributions of secondary γ-rays to the total absorbed doses between their target organs. These findings will help determine RBE by ICRP for preventing tissue reactions. [ABSTRACT FROM AUTHOR]

Herein we report the method to tailor the band gap and UV absorption of polyvinyl alcohol (PVA)/graphene oxide (GO)‐silver (Ag)/glutaraldehyde (GA) hybrid polymer nanocomposites. The modifications brought by neutron irradiation to the optical and dielectric characteristics enabled the band gap and UV absorption‐tailored polymer nanocomposites to be obtained. Neutron‐irradiated samples, compared with their unirradiated counterparts, exhibit a reduction in transmittance to 78%, rendering them opaque to UV–visible light after irradiation. The energy band gap decreases from 5.25 to 4.09 eV upon irradiation. Furthermore, upon neutron‐irradiation the relaxation time increases from 7.63 × 10−4 to 0.02 s which is evident by the shift in electric modulus imaginary part (M") peak to a lower frequency region, indicating an increase in relaxation time. The Cole–Cole plot for irradiated samples demonstrates lower fitting parameter (α) values of the modified Havriliak–Negami function, indicating a departure from pure capacitor‐like behavior. The neutron irradiation leads to a decrease in conductivity from 44.6 × 10−7 to 0.09 × 10−7 S/cm. [ABSTRACT FROM AUTHOR]

High strength, high conductivity copper alloys that can resist creep at high temperatures are one of the primary candidates for efficient heat exchangers in fusion reactors. Cu–Cr–Nb–Zr (CCNZ) alloys, which were designed to improve the strength and creep life of ITER Cu–Cr–Zr (CCZ) reference alloys, have been found to have comparable electrical conductivity and tensile properties to CCZ alloys. The measured creep rupture times for these improved alloys is about ten times higher than the ITER reference alloys at 90–125 MPa at 500 °C. However, the effects of neutron irradiation on these alloys, and the ensuing material properties, have not been studied; thus, their utility in a fusion reactor environment is not well understood. This study characterizes the room temperature mechanical and electrical properties of a neutron-irradiated CCNZ alloy and compares them to a neutron-irradiated ITER reference heat sink CCZ alloy. Tensile specimens were neutron irradiated in the High Flux Isotope Reactor (HFIR) to 5 dpa between 250 °C and 325 °C. Post-irradiation characterization included electrical resistivity measurements, hardness, and tensile tests. Microstructural evaluation used scanning electron microscopy, energy dispersive x-ray spectroscopy, and atom probe tomography to characterize the irradiation-produced changes in the microstructure and investigate the mechanistic processes leading to post-irradiation properties. Transmutation calculations were validated with composition measurements from atom probe data and used to calculate contributions to the increased electrical resistivity measured after irradiation. Comparisons with CCZ alloys in the same irradiation heat found that the post-irradiated CCNZ and CCZ alloys had comparable electrical resistivity. Although CCNZ alloys suffered more irradiation hardening than CCZ, the overall tensile behavior deviated very little from non-irradiated values in the temperature range studied.

Studies of the radiation tolerance and electrical behavior of gallium nitride (GaN) based devices are important for the next generation of high-power and high-voltage electronics that may be subjected to harsh environments such as nuclear reactor and fusion facilities, particle accelerators, and post-denotation environments. In this work, we study the behavior of Ga-polar and N-polar GaN Schottky diodes before and after exposure to fast and thermal + fast neutrons. Temperature-dependent current–voltage (I–V) and circular transmission line method (CTLM) measurements were used to study the electrical characteristics. A strong reduction in reverse leakage current and an increase in differential resistance in forward bias were observed after neutron irradiation. Thermionic emission (TE), Frenkel–Poole (FP) emission, and Fowler–Nordheim (FN) tunneling models were used to explain the forward and reverse I–V characteristics pre- and post-irradiation. The study confirms that Ga-polar and N-polar GaN Schottky diodes exhibit different electrical responses to fast and thermal neutron irradiations. The reverse bias characteristics of N-polar diodes are less affected after the fast neutron irradiation compared to Ga-polar diodes, while in the forward bias region, the electrical behavior after fast and thermal neutron irradiations is similar in Ga-polar and N-polar diodes. The results indicate that the role of orientation should be considered in the design of GaN-based radiation-tolerant electronics. [ABSTRACT FROM AUTHOR]

This Special Topic "Radiation Effects in Materials" is a broad collection of scientific studies addressing the interaction of radiation with condensed matter, a long-standing issue that is relevant for a range of key energy technologies. With the discovery of nuclear fission and its use for energy production, the study and understanding of the effects of radiation on materials got a strong engineering dimension. As noted above, the principle of scintillators is based on the interaction between radiation and matter, and the increasing uses of radiation in our society stimulate the search for better performing materials. [Extracted from the article]

Titanium-modified austenitic stainless steels (15-15TiSS) are currently used as the fuel cladding material of fast reactors, which are subject to higher radiation damage during their application. In this work, the radiation-induced swelling of 15-15TiSS under a fast reactor neutron and heavy ion irradiation conditions was studied by the rate theory (RT). The simulated swelling properties of 15-15TiSS under fast neutron conditions were calculated initially. The swelling peak, swelling rates, and swelling-related microstructural properties are consistent with the neutron irradiation results, indicating that the selected RT model and material parameters are reasonable. Then, the swelling properties of 15-15TiSS under various damage rates were predicted by changing the radiation damage rates from 1 × 10−6 to 1 × 10−3 dpa/s. It shows that swelling peaks are strongly dependent on temperature and the swelling peaks shift ∼50 °C toward the higher temperature with each order of magnitude increase of defects generation rate. The swelling rates and swelling-related defect evolution at 1 × 10−3 dpa/s (with a swelling peak temperature of 590 °C) are consistent with that under neutron irradiation with 1 × 10−6 dpa/s (with a swelling peak temperature of 460 °C). At length, the RT-predicted heavy ions irradiation results were verified by the previous positron annihilation lifetime spectroscopy results of ions irradiated 15-15TiSS. It indicates that heavy ion irradiation can be used to study the radiation effect of materials under neutron irradiation and should be a feasible technique used in the further screening of radiation-resistant materials. [ABSTRACT FROM AUTHOR]

An extensive investigation on the microstructural evolution of nanocrystalline–amorphous laminated alloys (NALAs) by molecular dynamics simulations and mechanistic analysis have been conducted to apprehend the interplay of complex phenomena governing structural changes in this alloy under neutron irradiation. It was discovered from the evolution profiles of free volumes, atomic unfilled spaces, and irradiation-induced vacancies that the profound structural response of the NALA was orchestrated by the rapid and spontaneous recovery of free volumes that indicate a self-healing ability in the amorphous zone, while the phenomenon of geometric atomic reconstitution in local structures governs the effective self-healing capacity for annihilated nanocrystal regions. Furthermore, a distinctive, self-migration/diffusion capture dynamics for the annihilation of defects by phase boundaries was discovered as an effective self-healing mechanism in NALAs. These findings will potentially facilitate the development of advanced nuclear materials with high irradiation resistance. [ABSTRACT FROM AUTHOR]

Irradiation creep is known to be an important process for structural materials in nuclear environments, potentially leading to creep failure at temperatures where thermal creep is generally negligible. While there is a great deal of data for irradiation creep in steels and zirconium alloys in light water reactor conditions, much less is known for first wall materials under fusion energy conditions. Lacking suitable fusion neutron sources for detailed experimentation, modeling, and simulation can help bridge the dose-rate and spectral-effects gap and produce quantifiable expectations for creep deformation of first wall materials under standard fusion conditions. In this paper, we develop a comprehensive model for irradiation creep created from merging a crystal plasticity representation of the dislocation microstructure and a defect evolution simulator that accounts for the entire cluster dimensionality space. Both approaches are linked by way of a climb velocity that captures dislocation-biased defect absorption and a dislocation strengthening term that reflects the accumulation of defect clusters in the system. We carry out our study in Fe under first wall fusion reactor conditions, characterized by a fusion neutron spectrum with average recoil energies of 20 keV and a damage dose rate of ≈ 3 × 10 − 7 dpa/s at temperatures between 300 and 800 K. [ABSTRACT FROM AUTHOR]

Simple Summary: Erect leaves are one of the important phenotypes for plants to adapt to dense planting. This study obtained the erect leaf mutant mths29 through fast neutron irradiation and directional breeding. Dynamic observation of lamina joint development in the mutant and its genetic parent Heng S29 revealed an extreme phenotype during the booting stage, characterized by the complete absence of lamina joint on the inverted second leaves and flag leaves, resulting in a close adhesion of the leaf blade to the stem and the formation of an erect leaf phenotype. Through map-based cloning, the erect leaf QTL was localized within a physical interval of 1.03 Mb on chromosome 5A, and four potential candidate genes were predicted. Here, we demonstrate that mths29 represents a novel genetic resource for erect leaf traits in wheat. This study contributes to a better understanding of lamina joint development in graminaceous and aids in shaping plant architecture for denser planting. The erect leaf plays a crucial role in determining plant architecture, with its growth and development regulated by genetic factors. However, there has been a lack of comprehensive studies on the regulatory mechanisms governing wheat lamina joint development, thus failing to meet current breeding demands. In this study, a wheat erect leaf mutant, mths29, induced via fast neutron mutagenesis, was utilized for QTL fine mapping and investigation of lamina joint development. Genetic analysis of segregating populations derived from mths29 and Jimai22 revealed that the erect leaf trait was controlled by a dominant single gene. Using BSR sequencing and map-based cloning techniques, the QTL responsible for the erect leaf trait was mapped to a 1.03 Mb physical region on chromosome 5A. Transcriptome analysis highlighted differential expression of genes associated with cell division and proliferation, as well as several crucial transcription factors and kinases implicated in lamina joint development, particularly in the boundary cells of the preligule zone in mths29. These findings establish a solid foundation for understanding lamina joint development and hold promise for potential improvements in wheat plant architecture. [ABSTRACT FROM AUTHOR]