Search Results (217)

Nuclear energy can help stop climate change by generating large amounts of emission-free electricity. Nuclear reactor designs are continually being developed to be more fuel efficient, safer, easier to construct, and to produce less nuclear waste. The term advanced nuclear reactors refers either to Generation III+ and Generation IV or small modular reactors. Every reactor is associated with the nuclear fuel cycle that must be economically viable and competitive. An important matter is optimization of fissile materials used in reactor and/or reprocessing of spent fuel and reuse. Currently operating reactors use the open cycle or partially closed cycle. Generation IV reactors are intended to play a significant role in reaching a fully closed cycle. At the same time, we can observe the growing interest in development of small modular reactors worldwide. SMRs can adopt either fuel cycle; they can be flexible depending on their design and fuel type. Spent nuclear fuel management should be an integral part of the development of new reactors. The proper management methods of the radioactive waste and spent fuel should be considered at an early stage of construction. The aim of this paper is to highlight the challenges related to reprocessing of new forms of nuclear fuel. Full article

Refractory high-entropy alloys (HEAs) are promising candidates for next-generation nuclear applications, particularly fusion reactors, due to their excellent high-temperature mechanical properties and irradiation resistance. Here, the microstructure and mechanical behavior were investigated for an equimolar WTaTiVZr HEA, designed from a palette of low-activation elements. The as-cast alloy exhibited a dendritic microstructure composed of W-Ta rich dendrites and Zr-Ti-V rich inter-dendritic regions, both possessing a body-centered cubic (BCC) crystal structure. Room temperature bulk compression tests showed ultra-high strength of around 1.6 GPa and plastic strain ~6%, with fracture surfaces showing cleavage facets. The alloy also demonstrated excellent high-temperature strength of ~650 MPa at 500 °C. Scratch-based fracture toughness was ~38 MPa√m for the as-cast WTaTiVZr HEA compared to ~25 MPa√m for commercially used pure tungsten. This higher value of fracture toughness indicates superior damage tolerance relative to commercially used pure tungsten. These results highlight the alloy’s potential as a low-activation structural material for high-temperature plasma-facing components (PFCs) in fusion reactors. Full article

Temperature dependencies of the density, heat capacity at constant pressure, and isobaric thermal expansion coefficient are investigated for two liquid metal nuclear reactor coolants: pure sodium and sodium–potassium eutectic alloy (31.9 at. %Na). The variational method of the thermodynamic perturbation theory is used for the calculations. The calculations were carried out in temperature ranges of 373–1673 K for Na and 273–1573 K for 0.319Na-0.681K. The accuracy of two local pseudopotentials and three exchange–correlation functions is estimated. It is shown that two combinations between the pseudopotential and exchange–correlation function can be recommended for predicting the properties at high temperatures for which experimental information is absent. Full article

Lithium hydride (LiH) is one promising material for nuclear reactor shielding due to its high hydrogen content, but its poor mechanical strength and thermal conductivity pose challenges for fabricating large, crack-free ceramic components via conventional sintering. This study explores microwave sintering as a potential solution to enhance heating uniformity and reduce thermal stress during densification of bulk LiH ceramics. Using implicit function and level set methods, we numerically simulated the microwave field distribution and thermal response in both stationary and rotating samples. The results show that rotational heating improves temperature uniformity by up to 12.9% for specific samples, although uniform temperature control remains difficult through rotation alone. To mitigate stress accumulation from thermal gradients, we propose a cyclic sintering–resting strategy, which leverages LiH’s tensile strength–temperature envelope to guide safe and efficient processing. This strategy successfully reduced total sintering time from several days to 1.63 h without inducing cracks. Our findings offer practical insights into optimizing microwave sintering parameters for large-scale LiH ceramic production and contribute to enabling its application in advanced nuclear shielding systems. Full article

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

Nuclear energy cogeneration, which integrates electricity generation with thermal energy utilization, presents a transformative pathway for enhancing energy efficiency and decarbonizing industrial and urban sectors. This comprehensive review synthesizes advancements in technological stratification, economic modeling, and sectoral practices to evaluate the viability of nuclear cogeneration as a cornerstone of low-carbon energy transitions. By categorizing applications based on temperature requirements (low: <250 °C, medium: 250–550 °C, high: >550 °C), the study highlights the adaptability of reactor technologies, including light water reactors (LWRs), high-temperature gas-cooled reactors (HTGRs), and molten salt reactors (MSRs), to sector-specific demands. Key findings reveal that nuclear cogeneration systems achieve thermal efficiencies exceeding 80% in low-temperature applications and reduce CO₂ emissions by 1.5–2.5 million tons annually per reactor by displacing fossil fuel-based heat sources. Economic analyses emphasize the critical role of cost allocation methodologies, with exergy-based approaches reducing levelized costs by 18% in high-temperature applications. Policy instruments, such as carbon pricing, value-added tax (VAT) exemptions, and subsidized loans, enhance project viability, elevating net present values by 25–40% for district heating systems. Case studies from Finland, China, and Canada demonstrate operational successes, including 30% emission reductions in oil sands processing and hydrogen production costs as low as USD 3–5/kg via thermochemical cycles. Hybrid nuclear–renewable systems further stabilize energy supply, reducing the levelized cost of heat by 18%. The review underscores the necessity of integrating Generation IV reactors, thermal storage, and policy alignment to unlock nuclear cogeneration’s full potential in achieving global decarbonization and energy security goals. Full article

The study explores the resistance of high-strength C40/50 concrete with steel fiber and silica fume admixture to high temperature and gamma radiation. The purpose is to create concrete composites with radiation shielding properties and high temperature resistance for use in nuclear power plants and radioactive waste storage facilities. For that purpose, concrete specimens containing 0.64 wt% industrial steel fiber and different proportions of silica fume (0%, 5%, 10%, 15%) were first subjected to high temperature according to ISO 834 and ASTM E119 after 28 days of curing at a target temperature of 900 °C based on a working fire scenario and then subjected to 94 kGy gamma radiation and analyzed using compressive strength, flexural strength, ultrasonic pulse velocity (UPV), SEM-EDX and XRD tests. It was found that 94 kGy gamma radiation increased the compressive strength of steel fiber concrete by SFC 20.98%, SFC-5 26.36%, SFC-10 26.45%, and SFC-15 25.34%, flexural strength by SFC 24.85%, SFC-5 25.06%, SFC-10 24.11%, and SFC-15 23.65%, and led to microstructure improvement and densification. XRD analysis revealed that samples exposed to 94 kGy gamma radiation accumulated and increased their calcite peak, resulting in decreased porosity and increased compressive and flexural strength. Under high temperature (900 °C) conditions, a significant decrease in the mechanical properties of concrete was observed in the compressive strength of SFC 78.99%, SFC-5 76.71%, SFC-10 76.62% and SFC-15 76.05% and in the flexural strength of SFC 79.44%, SFC-5 78.66%, SFC-10 79.68% and SFC-15 80.11%. In conclusion, results highlight the synergistic role of silica fume in reducing porosity and enhancing radiation-induced cement matrix reactivity, as well as that of steel fibers in improving thermal shock resistance and residual mechanical integrity. The developed composite materials are promising candidates for structural and shielding components in nuclear reactors, radioactive waste storage units, and other critical infrastructures requiring long-term durability under combined thermal and radiological loading. Full article

Inconel 617 is a nickel-based superalloy that is a primary candidate for use in next-generation nuclear applications such as the Gen IV Molten Salt Reactor (MSR) and Very-High-Temperature Reactor (VHTR) due to its corrosion and oxidation resistance and high strength in elevated temperatures. However, Inconel 617 machinability is poor due to its hardness and tendency to work harden during manufacturing. While the machinability of its sister grade, Inconel 718, has been widely studied and understood due to its applications in aerospace, there is a lack of knowledge regarding the behaviour of Inconel 617 in machining. To address this gap, this paper investigates the influence of cutting parameters in the turning of Inconel 617 and compares the impact of Minimum Quantity Lubrication (MQL) turning against conventional coolant. This investigation was performed through three distinct studies: Study A compared the performance of commercial coatings, Study B investigated the influence of cutting parameters on the surface finish, and Study C compared the performance of MQL to flood coolant. This work demonstrated that AlTiN coatings performed the best and doubled the tool life of a standard tungsten carbide insert compared to its uncoated form. Additionally, the feed rate had the largest impact on the surface roughness, especially at high feeds, with the best surface quality found at the lowest feed rate of 0.075 mm/rev. The utilization of MQL had mixed results compared to a conventional flood coolant in the machining of Inconel 617. Surface finish was improved as high as 47% under MQL conditions compared to the flood coolant; however, work hardening at the surface was also shown to increase by 10–20%. Understanding this, it is possible that MQL can completely remove the need for a conventional coolant in the machining of Inconel 617 components for the manufacturing of next-generation reactors. Full article

The creep properties of 15Kh2NMFAA nuclear WWER (water–water energetic reactor) vessel steel in the range of 500–1200 °C temperatures, which may appear during severe nuclear reactor accidents, were investigated. The present paper attempts to analyze the creep curves obtained from tensile testing at high temperatures using the Larson–Miller parametric technique. The power law rate and material coefficient of Norton’s equation with the Monkman–Grant relationship coefficient were found for each test temperature. It is shown that in accordance with the Monkman–Grant relationship coefficient values, changing the creep type from dislocation glide to high temperature dislocation climb occurs in the temperature range of 600–700 °C, which leads to a slope change in the Larson–Miller parameter plot and the conversion of steel creep behavior. It is also shown that in the range of $A_1$–$A_3$ temperatures, a stepwise change in creep characteristics occurs, which is associated with phase transformations. In addition, the constancy of the product of the time to rupture ${\tau }_r$ and the minimum creep rate ${\dot{ϵ}}_{min}$ in the ranges of 600–700 °C and $A_3$—1200 °C was noted. The proposed approach improves the accuracy of time to rupture estimation of 15Kh2NMFAA steel by at least one order of magnitude. Based on the research results, the calculated dependence of the steel’s long-term strength limit on temperature was obtained for several time bases, allowing us to increase the accuracy of material survivability prediction in the case of a severe accident at a nuclear reactor. Full article

Oxide dispersion-strengthened (ODS) steels are emerging as leading candidate materials for next-generation nuclear reactor components due to their exceptional resistance to creep, fatigue, and irradiation, combined with high strength at elevated temperatures. This paper investigates the microstructural mechanisms underpinning these superior properties, with a particular focus on the critical role of nano-oxides in enhancing performance. Various manufacturing techniques, including powder metallurgy and additive manufacturing, are reviewed to assess their impact on the structural and mechanical properties of ODS steels. Recent case studies on their application in nuclear environments highlight the potential of ODS steels to significantly extend component longevity without necessitating major reactor redesigns. Nevertheless, further research is necessary to assess their reliability under extreme environmental conditions and to determine optimal, scalable manufacturing processes for large-scale production. Full article

Increasing the efficiency and capacity of nuclear power units is a promising direction for the development of power generation systems. Unlike thermal power plants, nuclear power plants operate at relatively low temperatures of the steam working fluid. Due to this, the thermodynamic efficiency of such schemes remains relatively low today. The temperature of steam and the efficiency of nuclear power units can be increased by integrating external superheating of the working fluid into the schemes of steam turbine plants. This paper presents the results of a thermodynamic analysis of thermal schemes of NPPs integrated with hydrocarbon-fueled plants. Schemes with a remote combustion chamber, a boiler unit and a gas turbine plant are considered. It has been established that superheating fresh steam after the steam generator is an effective superheating solution due to the utilization of heat from the exhaust gases of the GTU using an afterburner. Furthermore, there is a partial replacement of high- and low-pressure heaters in the regeneration system, with gas heaters for condensate and steam superheating after the steam generator for water-cooled and liquid-metal reactor types. An increase in the net efficiency of the hybrid NPP is observed by 8.49 and 5.11%, respectively, while the net electric power increases by 93.3 and 76.7%. Full article

SiC matrix composites are widely used in high-temperature structural components of aircraft engines and nuclear reactor materials because of their excellent properties such as their high modulus, high strength, corrosion resistance, and high-temperature resistance. However, the bonding of SiCf/SiC composites poses significant challenges in practical engineering applications, primarily due to residual stresses, anisotropy in composite properties, and the demanding conditions required for high-performance joints. This work reviews various bonding technologies for SiC ceramics and SiC matrix composites. These include solid-state diffusion bonding, NITE phase bonding, direct bonding without filling materials, MAX phase bonding, glass ceramic bonding, polymer precursor bonding, metal brazing bonding, and Si-C reaction bonding. Key results, such as the highest bending strength of 439 MPa achieved with Si-C reaction bonding, are compared alongside the microstructural characteristics of different joints. Additionally, critical factors for successful bonding, such as physical mismatch and metallurgical incompatibility, are discussed in detail. Future research directions are proposed, emphasizing the optimization of bonding techniques and evaluation of joint performance in harsh environments. This review provides valuable insights into advancing bonding technologies for SiC composites in aerospace and nuclear applications. Full article

Defect detection in industrial computed tomography (CT) images remains challenging due to small defect sizes, low contrast, and noise interference. To address these issues, we propose Defect R-CNN, a novel detection framework designed to capture the structural characteristics of defects in CT images. The model incorporates an edge-prior convolutional block (EPCB) that guides to focus on extracting edge information, particularly along defect boundaries, improving both localization and classification. Additionally, we introduce a custom backbone, edge-prior net (EP-Net), to capture features across multiple spatial scales, enhancing the recognition of subtle and complex defect patterns. During inference, the multi-branch structure is consolidated into a single-branch equivalent to accelerate detection without compromising accuracy. Experiments conducted on a CT dataset of nuclear graphite components from a high-temperature gas-cooled reactor (HTGR) demonstrate that Defect R-CNN achieves average precision (AP) exceeding 0.9 for all defect types. Moreover, the model attains mean average precision (mAP) scores of 0.983 for bounding boxes (mAP-bbox) and 0.956 for segmentation masks (mAP-segm), surpassing established methods such as Faster R-CNN, Mask R-CNN, Efficient Net, RT-DETR, and YOLOv11. The inference speed reaches 76.2 frames per second (FPS), representing an optimal balance between accuracy and efficiency. This study demonstrates that Defect R-CNN offers a robust and reliable approach for industrial scenarios that require high-precision and real-time defect detection. Full article

In this study, a 56-group covariance library was generated based on the recently released JENDL-5 covariance data, which cover 105 isotopes. The AMPX-6 code system facilitated the generation of this library. Subsequently, the TSUNAMI-IP code was employed to estimate the uncertainty in the effective neutron multiplication factor (keff) for the critical experiment conducted in the Japanese High-Temperature Test Reactor (HTTR). Our analysis involved comparing results obtained from three nuclear data libraries: JENDL-5, ENDF/B-VIII.0, and ENDF/B-VII.1. The keff uncertainty originated from the nuclear data of JENDL-5, ENDF/B-VIII.0, and ENDF/B-VII.1 and were estimated to be 0.387%, 0.581%, and 0.556%, respectively. Interestingly, when the JENDL-5 covariance library was combined with ENDF/B-VIII.0 for JENDL-5 nuclides lacking covariance data, the keff uncertainty increased to 0.464%. The primary contributors to the keff uncertainty, ranked in decreasing order, were U-235 (nubar), C-12 (n,gamma), U-235 (fission), C-12 (elastic), and U-238 (n,gamma). Notably, significant differences in the keff uncertainty were observed between JENDL-5 and ENDF/B-VIII.0, particularly for U-235 (nubar) and C-12 (elastic). Additionally, the sensitivity coefficients, similarity, and kinetics parameters were evaluated across the three libraries, leading to insightful inter-library comparison results. Full article

The topic of hydrogen as an energy vector is widely discussed in the present literature, being one of the crucial technologies aimed at human carbon footprint reduction. There are different hydrogen production methods. In particular, this paper focuses on Steam Methane Reforming (SMR), which requires a source of high-temperature heat (around 900 °C) to trigger the chemical reaction between steam and CH₄. This paper examines a plant in which the reforming heat is supplied through a helium-cooled high-temperature nuclear reactor (HTR). After a review of the recent literature, this paper provides a description of the plant and its main components, with a central focus on the safety and reliability features of the combined nuclear and chemical system. The main aspect emphasized in this paper is the assessment of the hydrogen production reliability, carried out through Failure Modes and Effects Analysis (FMEA) with the aid of simulation software able to determine the quantity and origin of plant stops based on its operational tree. The analysis covers a time span of 20 years, and the results provide a breakdown of all the failures that occurred, together with proposals aimed at improving reliability. Full article