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Metallic fuels hold numerous advantages over conventional uranium dioxide fuels and are a key component of several liquid metal-cooled advanced reactor concepts including sodium fast reactors. These fuels undergo rapid swelling during early burnup; consequently, they spend most of their reactor lifetime in a porous state. The presence of this porosity alters many of the mechanical properties of the fuel including creep impacting fuel deformation during axial swelling. This work investigates the creep behavior of the porous fuel using a spark plasma sintering technique. Creep tests were performed for the first time on porous α-phase uranium and uranium with 10 wt. % zirconium (U-10Zr) samples. The samples of α-phase uranium and U-10Zr were fabricated from depleted uranium by spark plasma sintering and subjected to uniaxial compressive creep testing. Calculated stress exponents were found to be 2.6 ± 1.6 and 5.7 ± 1.4 for α-U and U-10Zr, respectively, and calculated activation energies were found to be 61.6 ± 1.1 kJ / mol for α-U. The creep data were also used to evaluate existing porosity inclusive in creep models. [ABSTRACT FROM AUTHOR]

A-site Sr or Ca substituted perovskite LaCr 0.7 Ni 0.3 O 3 (LSCN, LCCN) are prepared in this work as catalysts of simulated diesel fuel (N-hexadecane) steam reforming for the on-board hydrogen supplement of solid oxide fuel cells (SOFCs). The effect of different dopants on active metals dispersion and surface properties on catalyst performance is analyzed. The results of the investigation reveal that LCCN possesses the highest catalytic activity coupled with exceptional stability, achieving full fuel conversion at WHSV = 5 mL/g·h, S/C = 3.0, and 750 °C and keeping stable for 200 h, thereby emerging as a potential candidate for liquid fuel processing. SEM, H 2 -pulse chemisorption and XPS results confirm that the excellent performance is due to the high metal dispersion and steam activation capacity. The poor catalytic performance observed in LSCN is primarily attributed to the presence of Sr segregation and the formation of the SrCrO 4 second phase. Sr segregation decreases the steam activation ability of the catalyst as confirmed by XPS. DFT calculation also shows that Sr dopant and Sr segregation decrease the exsolution trend of metal Ni in the perovskite matrix, leading to poor metal dispersion. A simulated reforming gas is used in SOFC and the cell can keep stable for 120 h at a discharging current density of 0.4 A/cm2. This study analyzes the difference between Ca and Sr dopants, and reveals the detrimental effect of Sr segregation, which could enlighten the effect of surface tunning on the performance of perovskite catalysts. [ABSTRACT FROM AUTHOR]

During the γ phase–δ phase transition, U-50Zr fuel experiences spinodal decomposition, which has a significant effect on fuel properties. However, little is known about the spinodal decomposition of U-50Zr. The spinodal decomposition behavior in U-50Zr is studied in this research using the phase-field approach. The mechanism of spinodal decomposition from a thermodynamic perspective is studied, and the effects of temperature and grain boundary (GB) on spinodal decomposition are analyzed. It is found that the concentration of U atoms in the U-rich phase formed during spinodal decomposition is as high as 90%. The U-rich phase first appears at the GB position, and precipitation phases appear inside the grain later. Ostwald ripening occurs when larger precipitation phases on the GB absorb isolated smaller precipitation phases inside the grain. The coarsening rate of precipitation phases and the time it takes for spinodal decomposition to achieve equilibrium are both influenced by temperature. [ABSTRACT FROM AUTHOR]

Aluminum-boron composite powders were prepared mechanical milling and consolidated using uniaxial pressing. Both, spheroidal and irregularly shaped powders were prepared from the same starting materials. The product powder morphology was determined by the type of liquid process control agent. Highest strength was observed for the pellets made of spheroidal powders without any binder. For all milled powders, the main oxidation exotherm was delayed compared to the blended starting materials. For the pellets made of spheroidal powders heated in inert gas, an exotherm initiated just above 400°C while no such exotherm was detected for the pellets pressed using other composite powders. [ABSTRACT FROM AUTHOR]

Production of rocket propellants from lunar resources has the potential to significantly reduce the cost of space exploration. Recent research efforts in this area were focused on the extraction of water from icy regolith for conversion into hydrogen and oxygen, a highly efficient rocket bipropellant. However, water is available only in polar regions of the Moon, and its extraction is a challenge. The present paper aims to assess the feasibility of using propellant components that can be obtained from lunar regolith, specifically oxygen, metal alloys, and sulfur. Thermodynamic performance characteristics of rocket engines using these components were calculated over wide ranges of oxidizer-to-fuel mass ratios. It has been shown that the fuel obtained by extraction of oxygen from regolith, i.e., primarily a mixture of metal alloys, exhibits a relatively high specific impulse of up to 250 s. The use of fuel-lean propellants significantly decreases the temperatures, which facilitates cooling and potentially reduces the deposition of condensed products in the engine; at the same time, the expected decrease in the specific impulse is less pronounced. The use of sulfur in rocket engines is less promising from a thermodynamic point of view, but it enables engine designs without a need for feeding metal alloy powders. Among different designs of sulfur-based engines, a hybrid rocket (fuel: metal alloys mixed with sulfur, oxidizer: liquid oxygen) appears to be the most promising. • Rocket propellants can be directly sourced from lunar regolith. • Such regolith-derived fuels can produce a peak specific impulse of up to 250 s. • Sulfur can be used as either an oxidizer or additive to the regolith- derived fuel. • Different configurations for rocket engines using these fuels are presented. [ABSTRACT FROM AUTHOR]

To investigate the effects of metal fuels on the reactions of ammonium perchlorate (AP) oxidizer in propulsion sys¬tems, the energy release processes and reaction characteristics of two aluminum-based metal fuels, namely Al-Li alloy and Al-Mg alloy, were analyzed by TG-DSC, SEM, XRD, and a custom-designed combustion apparatus. The apparent activation en¬ergy was calculated by Kissinger method. The results reveals that the Al-Li alloy exhibits inhibitory effects on both the low-tem¬perature and high-temperature decomposition stages of AP, which elevates decomposition peak temperatures for both stages. In contrast, the Al-Mg alloy has a strong promoting effect on the low-temperature decomposition stage of AP, lowering the de¬composition peak temperature to 287. 3 °C . The addition of Al-Li alloy results in an apparent activation energy of 129. 7 kj/mol for the first decomposition stage of AP and approximately 247.0kJ/mol for the second stage. Conversely, the addition of Al-Mg alloy leads to a negative apparent activation energy ( - 207. 2 kj/mol) for the first decomposition stage of AP. Additional¬ly, in the Al-Mg alloy/AP system, a vigorous decomposition of AP is observed, accompanied by the generation of a prominent gaseous flame during sample combustion. In this process, aluminum and magnesium are nearly fully consumed. However, in the Al-Li alloy/AP system, aluminum is still detected among the combustion products. [ABSTRACT FROM AUTHOR]

The carbon‐free chemical storage and release of renewable energy is an important task to drastically reduce CO2 emissions. The high specific energy density of iron and its recyclability makes it a promising storage material. Energy release by oxidation with air can be realized by the combustion of micron‐sized iron powders in retro‐fitted coal fired power plants and in fixed‐bed reactors under milder conditions. An experimental parameter study of iron powder oxidation with air was conducted based on thermogravimetric analysis in combination with wide‐angle X‐ray scattering and Mössbauer spectroscopy. In agreement with literature the oxidation was found to consist of a very fast initial oxidation of the outer particle layer followed by much slower oxidation due to diffusion of iron ions through the Fe2O3/Fe3O4 layer being the rate‐limiting step. Scanning electron microscopy analysis of the iron particle before and after oxidation reveal a strong particle morphology transformation. This impact on the reaction was studied by cyclization experiments. Up to 10 oxidation‐reduction cycles show that both, oxidation and reduction rates, increase strongly with cycling due to increased porosity. [ABSTRACT FROM AUTHOR]

The ignition and combustion behaviors of single-particle aluminum in a water vapor environment are among the most important basic research aspects of metal fuels and solid propulsion technologies. In this paper, the ignition and combustion behaviors of aluminum particles in a water vapor environment were modeled based on a traditional aluminum particle ignition model and the finite difference method. In addition, a metal single-particle ignition combustion test system was used to carry out relevant validation experiments. The validation results showed that the average error of the model remained within 10%. In addition, an initial oxide layer fusion module was established in conjunction with the results of a material mechanics study of Al/Al2O3. Moreover, the model was used to calculate the ignition behavioral parameters (ignition delay time and ignition temperature) of the aluminum particles under different initial parameters. Finally, an intrinsic mechanism model was created to evaluate the influences of the relevant parameters on the ignition behaviors of the aluminum particles. The model results showed that the initial oxide layer ruptured during the aluminum melting stage, the phase transition stress was the main factor leading to oxide layer rupture, the ambient temperature had a great influence on the ignition temperature, and all four initial parameters were negatively correlated with the ignition delay time. [ABSTRACT FROM AUTHOR]

Metallic alloy fuels from fast reactors will be reprocessed by a non‐aqueous electrochemical technique known as electrorefining. Electrorefining of spent metal fuel results in the accumulation of heat‐generating fission products, especially 137Cs in the eutectic salt. These fission products need to be removed from the salt so as to reduce the decay heat load and contamination. The melt crystallization technique is a simple separation process being pursued for the separation of fission products. This is a single‐step process that utilizes the difference in solubility of fission products in the solid and liquid phase. This process is also less energy intensive. Crystallization involves the purification of a substance from a liquid mixture by solidification of the desired component. Since separation is based on selective solidification, which involves phase change, it is essential to evaluate the transient solidification pattern, liquid fraction distribution, solute distribution, and separation time and efficiency. Numerical modeling of the separation of CsCl from a LiCl‐KCl eutectic mixture has been carried out using Ansys Fluent (19.2). The effect of crystallizer geometry and cooling rates on the separation of CsCl has been numerically simulated. [ABSTRACT FROM AUTHOR]

The EU's energy transition necessitates availability of green energy carriers with high volumetric energy densities for long‐term energy storage (ES) needs. A fully decarbonized scenario considering renewable energy availability is analyzed underpinning the need for such carriers. Considering the shortcomings of Power‐to‐X technologies in terms of efficiency and low volumetric density, Aluminum (Al) is identified as a potential alternative showing significantly high volumetric energy densities (23.5 kWh L−1). In this paper, an Al‐based long‐term ES concept is investigated, taking advantage of the inherent recycling of the active species (i.e., Al2O3 to Al) coupling decarbonized Hall–Héroult process with an Al‐steam oxidation for simultaneous hydrogen (H2) and heat generation. This work demonstrates an innovative lab‐scale fine Al powder‐steam oxidation process at ≈900 °C without use of catalysts or additives, exploiting alumina as inert material. Conducted SEM‐EDX analysis on oxidized Al provides supporting evidence in favor of employed oxidation pathway, hindering tendency of aluminum oxide (Al2O3) clumping and enabling direct use of oxides in the smelting process for fully recyclability. Moreover, outcomes of XRD analyses are presented to validate the measured total H2 yields. [ABSTRACT FROM AUTHOR]

Automotive evaporative emission inventory is continuously increasing with less stringent evaporative emission norms and lack of control measures. Uncontrolled refuelling emissions from huge fleet of two-wheelers with high environmental temperature make this situation worst. Motorcycles are typically equipped with metallic fuel tanks which are exposed to direct sunlight causing very high temperature conditions inside them. In this work, two motorcycle fuel tanks are used to record the temperature of liquid gasoline, vapour in headspace and surface of fuel tank through data logger to closely assess the vapour generation environment. Also, fuel consumption behaviour determines the liquid-to-vapour ratio inside fuel tank and promotes the refuelling losses in the absence of onboard refuelling vapour recovery control technology in two-wheelers. Liquid-to-vapour ratio inside fuel tank depends on prefill gasoline volume and the quantity of gasoline refuelled. Experiments are conducted to develop understanding on the mechanism of vapour generation during refuelling. This paper focuses on studying the impact of refuelling quantity, prefill volume and ambient temperature conditions on the vapour generation during refuelling of two-wheeler fuel tanks. Also, interaction between these control factors with influence of individual factor is studied using regression analysis and Minitab. Analysis of variance study reveals that temperature has strong influence on vapour generation (61.5%) and refuelling quantity (21.18%) also affects it significantly with least influence of prefill volume (14.19%). Combined effect of prefill volume and refuelling quantity on vapour generation is found interesting in interaction plots. Further assessment of interaction between various control factors is suggested to develop optimized control solutions for two-wheeler refuelling emissions. [ABSTRACT FROM AUTHOR]

Estimation of Zr in fresh and irradiated metal alloy fuel is important. The homogeneous dissolver solution represents the fuel composition better compared to a highly heterogeneous solid pellet. The present study employs LIBS to determine Zr in the simulated dissolver solution. Four different compositions of U–Zr samples where the Zr/U ratio varies from 0.04 to 0.18 % are analyzed by LIBS with an in-house designed liquid sample cell. A good correlation coefficient is achieved for the measurements in the calibration plot. The results for identifying non-overlapping peaks, calibration plot, precision, deviation, and detection limit are discussed in detail. Two set of solid samples, an oxide pellet and metal alloy with similar Zr/U composition, are also analyzed by LIBS. The results obtained from these three set of samples are inter-compared, and the reason for getting a better Zr/U intensity ratio for a dried coating of sample on aluminium for a given composition is explained. [ABSTRACT FROM AUTHOR]

Metal fuels are considered as the promising candidates for future fast breeder reactors. Pyro-chemical reprocessing is the ideal method for reprocessing spent metallic fuels due to the inherent process advantages. Electrorefining run was demonstrated in a hot cell facility with irradiated U-6 wt% Zr alloy at 500 °C using LiCl–KCl eutectic melt. In order to understand the behavior of the actinides and various fission products during high-temperature electrolysis, various process streams, viz., irradiated metal alloy fuel, the eutectic salt, and the cathode deposit were analyzed for the uranium, plutonium, and other fission product contents. Various methods employed for characterizing the process streams and the behaviors of some of the fission products during the electrolysis process are highlighted. The major gamma emitting radionuclides present in the irradiated fuel were 106Ru, 125Sb, 134Cs, 137Cs, 144Ce, and 154Eu. During electrorefining, cesium, cerium and europium were oxidized and dissolved in the molten media, whereas ruthenium and antimony remained in the anode basket. A minor contamination of zirconium was found in the cathode deposit. [ABSTRACT FROM AUTHOR]

Methanol and hydrotreated vegetable oil (HVO) are complementary in the context of achieving ultra-low emission levels via low temperature combustion. HVO is a high-quality fuel fully compatible with compression ignition engines. Standalone methanol combustion is relatively straight-forward according to the Otto principle, with a spark ignited or in conventional dual-fuel ("liquid spark") engines. These two fuels have by far the largest reactivity span amongst commercially available alternatives, allowing to secure controllable partially premixed compression ignition with methanol–HVO emulsification. This study investigates the corrosion of aluminum, carbon steel, stainless steel, and a special alloy of MoC210M/25CrMo4+SH, exposed to different combinations of HVO, HVO without additives (HVOr), methanol, and emulsion stabilizing additives (1-octanol or 1-dodecanol). General corrosive properties are well determined for all these surrogates individually, but their mutual interactions have not been researched in the context of relevant engine components. The experimental research involved immersion of metal samples into the fuels at room temperature for a duration of 60 days. The surfaces of the metals were inspected visually and the dissolution of the metals into fuels was evaluated by analyzing the fuels' trace metal concentrations before and after the immersion test. Furthermore, this study compared the alterations in the chemical and physical properties of the fuels, such as density, kinematic viscosity, and distillation properties, due to possible corrosion products. Based on these results, methanol as 100% fuel or as blending component slightly increases the corrosion risk. Methanol had slight dissolving effect on aluminum (dissolving Al) and carbon steel (dissolving Zn). HVO, HVOr, and methanol–HVOr–co-solvents were compatible with the metals. No fuels induced visible corrosion on the metals' surfaces. If corrosion products were formed in the fuel samples, they did not affect fuel parameters. [ABSTRACT FROM AUTHOR]

The article focuses on the considerations of hydrogen from the perspective of welding and materials technology. Topics include its diverse industrial applications, the challenges hydrogen poses to metal properties and steel processing, and the risks associated with hydrogen uptake during steel production and further processing.

Uranium–zirconium metal-based Helical Cruciform Fuels (HCFs) have shown a promising prospect for their use in advanced nuclear reactors. However, during irradiation, dual-phase coexistence and the spatial heterogeneous distribution of zirconium atoms occur at higher powers, affecting the thermo-mechanical coupling behaviors and safety of fuel elements and assemblies. In this study, based on the phase-field approach, the coupled multi-field governing equations to describe the zirconium diffusion and phase evolution for U-Zr metallic fuels are improved. Furthermore, the corresponding numerical algorithms and procedures for multi-field coupling calculations are developed. The numerical predictions of zirconium atom fraction are in good agreement with the relevant experimental results, validating the developed models, algorithms and programs. The zirconium atom redistribution and phase transformation coupling behaviors in high-power U-10wt%Zr-based HCF rods are also obtained. Moreover, the complex evolution mechanisms of multi-field variables are analyzed. The results indicate the following: (1) the irradiation enhancement of the thermal mobility and chemical mobility plays a critical role in the redistribution of Zr atoms; (2) the multi-field results of HCF rods have helical symmetric characteristics; (3) the contribution competitions of the temperature gradient and chemical potential gradient within the α phase and γ phase significantly influence the zirconium-atom redistribution, with the zirconium-rich zones formed in the elbow region and the zirconium-poor zones appearing inside. These research efforts supply a foundation for the further involvement of mechanical fields in multi-field coupling computation. [ABSTRACT FROM AUTHOR]

The energy release process of the Mg-based hydroreactive fuels directly affects the performance of water ramjet engines, and the burning rate is one of the key parameters of the Mg-based hydroreactive fuels. However, there is not enough in-depth understanding of the combustion process of Mg-based hydroreactive fuels within the chamber of water ramjet engines, and there is a lack of effective means of prediction of the burning rate. Therefore, this paper aims to examine the flame structure of Mg-based hydroreactive fuels with a high metal content and analyze the impact of the water injection velocity and droplet diameter on the combustion property. A combustion experiment system was designed to replicate the combustion of Mg-based hydroreactive fuels within water ramjet engines, and the average linear burning rate was calculated through the target line method. On the basis of the experiment, a combustion–flow coupling solution model of Mg-based hydroreactive fuels was formulated, including the reaction mechanism between Mg/H2O and the decomposition products from an oxidizer and binder. The model was validated through experimental results with Mg-based hydroreactive fuels at various pressures and water injection velocities. The mean absolute percentage error (MAPE) in the experimental results was less than 5%, proving the accuracy and validity of the model. The resulting model was employed for simulating the combustion of Mg-based hydroreactive fuels under different water injection parameters. The addition of water injection resulted in the creation of a new high-temperature region, namely the Mg/H2O non-premixed combustion region in addition to improving the radial diffusion of the flame. With the increasing water injection velocity, the characteristic distance of Mg/H2O non-premixed combustion region is decreased, which enhances the heat transfer to burning surface and accelerates the fuel combustion. The impact of droplet parameters was investigated, revealing that larger droplets enhance the penetration of the fuel-rich gas, which is similar to the effect of injection velocity. However, when the droplet size becomes too large, the aqueous droplets do not fully evaporate, resulting in a slight decrease in the burning rate. These findings enhance the understanding of the mechanisms behind the burning rate variation in Mg-based hydroreactive fuels and offer theoretical guidance for the optimal selection of the engine operating parameters. [ABSTRACT FROM AUTHOR]

For the selective removal of Zr from PUREX originated acidic aqueous waste of metallic fuel, an adsorbent based on graphene oxide (GO)‐polystyrene composite functionalized with amide functional group was developed. Improved Hummers' oxidation of graphite powder was utilized to produce GO and the amide moiety was linked to GO via chemical functionalization. The amide modified GO was converted to GO‐polystyrene composite microspheres through pickering emulsion assisted route. FT‐IR, XRD and SEM analyses were employed to characterize the composite adsorbent. The adsorption behavior of Zr was examined under varying experimental conditions. Adsorption was modeled using several adsorption and kinetic models. The Zr adsorption capacity calculated based on the Langmuir adsorption isotherm and Pseudo‐first‐order models exhibited a close agreement. Adsorption studies using simulated U‐Pu‐Zr originated PUREX aqueous waste signifies the superior Zr‐adsorption capacity (~50 mg g−1), even in the presence of other possible interfering elements present in SHLLW. [ABSTRACT FROM AUTHOR]

The sluggish kinetics of oxygen reduction reactions (ORRs) require considerable Pd in the cathode, hindering the widespread of alkaline fuel cells (AFCs). By alloying Pd with transition metals, the oxygen reduction reaction's catalytic properties can be substantially enhanced. Nevertheless, the utilization of Pd-transition metal alloys in fuel cells is significantly constrained by their inadequate long-term durability due to the propensity of transition metals to leach. In this study, a nonmetallic doping strategy was devised and implemented to produce a Pd catalyst doped with P that exhibited exceptional durability towards ORRs. Pd3P0.95 with an average size of 6.41 nm was synthesized by the heat-treatment phosphorization of Pd nanoparticles followed by acid etching. After P-doping, the size of the Pd nanoparticles increased from 5.37 nm to 6.41 nm, and the initial mass activity (MA) of Pd3P0.95/NC reached 0.175 A mgPd−1 at 0.9 V, slightly lower than that of Pd/C. However, after 40,000 cycles of accelerated durability testing, instead of decreasing, the MA of Pd3P0.95/NC increased by 6.3% while the MA loss of Pd/C was 38.3%. The durability was primarily ascribed to the electronic structure effect and the aggregation resistance of the Pd nanoparticles. This research also establishes a foundation for the development of Pd-based ORR catalysts and offers a direction for the future advancement of catalysts designed for practical applications in AFCs. [ABSTRACT FROM AUTHOR]

In this study, a 3-D direct NH3 solid oxide fuel cell was numerically modeled to investigate the effects of NH3 inlet flow velocity, tube structure, and catalyst filling on the internal temperature distribution of the cell. The results show that shortening the length of the NH3 inlet tube and increasing the inlet flow velocity leads to an increase in the temperature difference inside the cell. By perforating the NH3 inlet tube, the temperature difference can be further reduced, and the low temperature zone inside the cell gradually decreases with the perforated area percentage increasing. In addition, placing NH3 decomposition catalyst inside the perforated inlet tube can further improve the temperature difference between the electrodes inside the cell, reducing it from 30 K to about 1 K. Furthermore, the temperature distribution pattern inside the fuel cell with metal supports was investigated, and it was found that the metal support can better export the heat generated inside the fuel cell. This study provides a new idea to improve the temperature distribution of direct NH3 solid oxide fuel cell and enhance the stability and reliability of cell operation. [ABSTRACT FROM AUTHOR]

Fluoropolymers have weak electroactive properties but are often paired with other materials (inclusions) to form a composite with enhanced electroactive properties and when those inclusions are a metal or metalloid fuel (e.g., Al, Si, B) they can then function as electroactive reactive materials. There is strong interest in understanding the electromechanical (piezo, flexo, dielectric) properties toward the development of multifunctional energetics. Specifically, in this effort, we report the influence of magnesium diboride (MgB2) on the electroactive and combustion properties in a composite system with the fluoropolymer tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride (THV). The dielectric, flexoelectric, piezoelectric, burning rate, and heat of reaction are investigated for composites with 50–70 wt. % MgB2 loading. It is observed that with an increase in solids loading that the dielectric, flexoelectric, and burning rate increase. For example, at 70 wt. % MgB2, the measured dielectric constant was 298 ± 10, and the flexoelectric coefficient was 16.6 ± 1.2 nC/m. Unexpectedly, a true piezoelectric coefficient (d33) was measured between 11.4 ± 0.2 and 13.0 ± 0.3 pC/N at these solids loadings. Due to the mechanical properties of these composite systems, an apparent piezoelectric coefficient of 108 pC/N was calculated indicating that these reactive materials are highly electroactive. The multifunctional properties are demonstrated by applying the force of the human body (via jumping) to a THV/MgB2 (50 wt. %) film. A peak voltage of 0.75 V was observed. This work indicates that a variety of reactive materials may offer multifunctional capabilities. [ABSTRACT FROM AUTHOR]

Approximately 130,000 metal fuel pins were irradiated in the Experimental Breeder Reactor II (EBR-II) during its 30 years of operation to develop and characterize existing and prospective fuels. For many of the metal fuel irradiation experiments, neutron radiography imaging was performed to characterize fuel behavior, such as fuel axial expansion. While several fuel expansion results obtained from neutron radiography imaging have been published, the analysis of neutron radiography for the purpose of describing statistical properties of porous matter formed on top of the fuel pins, also referred to as fluff in previous publications, is significantly less represented in the literature with just a single paper so far. This study aims to validate and augment results reported in previous publications using automated image processing. The paper describes the statistical properties of the porous matter in terms of nine parameters derived from radiography images and correlates those parameters with such fuel properties as composition, expansion, temperature, and burnup. The reported results are based on 1097 fuel pins of eight different fuel compositions. For three major fuel types, U-10Zr, U-8Pu-10Zr, and U-19Pu-10Zr, a clear negative correlation is found between the Pu content and five parameters describing the amount of porous matter generated. The parameters describing granularity properties, however, showed either negative correlation or nonlinear dependency from fuel composition. The parameters describing the amount showed a positive correlation with fuel axial expansion, while granularity parameters showed a negative correlation with axial expansion. The dependency on cladding temperature was found to be weak. A positive correlation is demonstrated for volume parameters and fuel burnup. In general, reported results confirm and validate findings published in previous studies using a much larger number of pins and automated processing techniques, which easily lend themselves to reproducibility, thus avoiding subjective bias. [ABSTRACT FROM AUTHOR]

In the dispersing process of liquid fuel or metal powder under the explosion load of a high explosive, the explosion product of central high-energy explosive expands. Flow of the explosion product with high temperature is coupled with the dispersing of fuel driven by the explosion load. When concentration of the dispersing fuel cloud and the current temperature meet critical condition for igniting the cloud, the fuel cloud will be ignited. If the dispersing fuel is ignited by the high temperature of the explosion product, the fuel cloud will burn, and the pre-designed detonation energy output cannot be achieved. Therefore, avoiding the ignition phenomenon in the process of fuel dispersion is an important issue in effective utilization of multi-phase cloud explosion energy. The minimum ignition temperature (MIT) of gas–liquid two-phase cloud is the basis for avoiding the dispersing fuel to be ignited under explosion load of a high explosive. In this study, the MITs of gas–liquid two-phase cloud of ethanol, octane, nitromethane, and isopropyl nitrate were measured. The MIT of gas–liquid two-phase cloud is a function of ignition temperature (IT) of vapor and atomization parameters of liquid fuel. The MIT of gas–liquid two-phase cloud of a liquid fuel is higher than IT of vapor of the liquid fuel. The MIT of gas–liquid two-phase cloud decreases with the decrease in droplet characteristic sizes. The prediction model of MIT of gas–liquid two-phase cloud of liquid fuel (MIT = 507 + 0.15 β 0.8 T i ) has been established in this study. If the ignition temperature of vapor of a liquid fuel and the atomization characteristic parameters of the liquid fuel are known, the MIT of gas–liquid two-phase cloud of the liquid fuel cloud be determined. The measured MITs of gas–liquid two-phase cloud for octane (C8H18), ethanol (C2H6O), nitromethane (CH3NO2), and isopropyl nitrate (C3H7NO3) are 616 K, 737 K, 692 K, and 671 K, respectively. The MITs of gas–liquid two-phase cloud predicted using the model in this study for the four liquid fuels are 621 K, 740 K, 690 K, and 663 K, respectively. The relative error of the predicted MITs is less than 3.5%. [ABSTRACT FROM AUTHOR]

Iron powder, classified as a metal, serves as a versatile energy carrier and stands as a compelling alternative to traditional fossil fuels. Its appeal lies in its remarkable abundance and wide availability, attributes that position it favorably as a sustainable energy source. Notably, iron-based fuels are characterized by their environmentally benign nature, thus constituting a valuable contribution to the realization of a carbon–neutral future. Given the ongoing concerns surrounding climate change, largely attributed to the combustion of fossil fuels and the subsequent emission of carbon dioxide, iron, with its substantial reserves, emerges as a prospective candidate to address the escalating global energy demands. Owing to its exceptional energy density, iron-based fuel holds the capacity to serve multifarious purposes, encompassing the generation of heat, electricity, and the propulsion of energy facilities and vehicular fleets. The noteworthy energy density of iron renders it an indispensable resource across a spectrum of industries and tools, allowing it to function as a reservoir of considerable potential. Iron powder exhibits the capacity to react with air and water, culminating in the production of both heat and electricity through the conversion of its inherent energy. Within the combustion of each iron particle, this chemical carrier behaves akin to a microreactor emitting heat, with the combustion rate of these particles remaining impervious to the ignition time. Furthermore, the combustion by-products of iron powder can be recycled and seamlessly integrated into clean energy technologies, minimizing carbon emissions. This comprehensive review seeks to provide a thorough assessment of renewable iron-based energy carrier. It will encompass an exploration of our current understanding of these fuels, including their reactivity with atmospheric air and the ignition mechanisms responsible for unleashing the flames of this promising energy source. While iron fuel, in its classification as a metal fuel, holds immense promise for the future energy landscape, its true environmental impact and the overall efficiency of the energy cycle remain subjects of ongoing study. This paper also examined both the practical applications and fundamental aspects of combustion involving iron powders, aiming to establish a comprehensive foundation essential for evaluating prospective metal engine technologies. Anticipated outcomes project energy and power densities of envisioned metal-fueled zero-carbon heat engines to approximate those of existing fossil-fuel-based combustion engines. This compelling similarity positions such engines as an enticing technological prospect for an impending era characterized by low-carbon imperatives. [ABSTRACT FROM AUTHOR]

Owing to its reflectivity, Copper manufacturing has always been challenging through laser-based additive manufacturing. In this study, we demonstrate additive/bulk manufacturing of copper using high velocity air fuel (HVAF) spray technology, an emerging variant in the thermal spray family. Rapid deposition of millimeter scale copper parts with good mechanical integrity and decent ductility, comparable to that of cold spray, has been shown feasible. The mechanical properties measured along different built directions showed no significance to be considered anisotropic. Electron backscattered diffraction analysis revealed the possibility of developing favorable bimodal grain distribution with a high volume fraction of ultrafine grains (>50%). However, the intersplat porosities and continuous pores were found to be detrimental despite the low overall porosity. HVAF technology demonstrates great potential and appears to be a promising process methodology for bulk/additive manufacturing of metals with a rapid production rate. [ABSTRACT FROM AUTHOR]

The article discusses the rise and success of Solar Industries India Ltd, a company that started as a low-cost mining explosive manufacturer but has since diversified into various sectors, including solar energy, defense, and infrastructure. The company's journey began in 1984 and has seen significant growth and expansion over the years. Solar Industries India Ltd has established itself as a major player in the industry, with a strong order book and a growing international presence. The article also mentions the company's stock performance and its alignment with the Indian government's Make in India initiative. The article concludes by mentioning the Strategic Partnership Model, which aims to engage the Indian private sector in the manufacture of defense equipment. [Extracted from the article]

Zirconium alloys have outstanding nuclear properties and are irreplaceable key materials for the development of nuclear power systems. The preparation of coatings on the surface of zirconium alloys is one of the potential solutions of fuel cladding materials. In this paper, the research progress of the preparation and high-temperature oxidation resistance of metal coating for fuel cladding zirconium alloys is reviewed, which includes the preparation method, coating-type selection, high-temperature oxidation resistance, and high-temperature oxidation failure mechanism of different coatings. This review provides important references for the development of fuel cladding zirconium alloy surface coating technology. [ABSTRACT FROM AUTHOR]

LaYO3 which has phase stability at high temperature is introduced as a promising candidate for reaction-preventing crucible materials with Uranium-Zirconium (U-Zr) melt containing rare-earth elements (RE). RE is composed of rare-earth elements such as Nd, Ce, Pr and La. The LaYO3 material was synthesized by a solid-state reaction method at elevated temperature according to a pseudo-phase diagram of LaYO3 and Y2O3. Green compacts blended with La2O3 and Y2O3 powder were made by the Cold Isostatic Pressing (CIP) method, with La2O3 and Y2O3 powders varying with molar ratios from 1.0 to 1:2. LaYO3 synthetics were fabricated at sintering temperatures ranging from 1450°C to 1600°C. LaYO3 pellets sintered at below 1550°C showed a highly dense orthorhombic phase with a perovskite structure, resulting in an enhancing reaction-resistant effect with RE. [ABSTRACT FROM AUTHOR]

Metal fuel is a promising candidate for the pyro-processed nuclear fuel, but the problem of loss of nuclear material due to the high reactivity of metal fuel and melting crucible in the metal fuel casting process must be solved for loss control and waste reduction. In this study, fabrication test was conducted to develop a new material NdYO3 as a new crucible material to improve the degree of anti-reactivity. The NdYO3 compact was manufactured by the CIP (Cold isostatic pressing) method with changing fraction of Nd2O3 and Y2O3 powders. Sintering process was performed at 1550°C for 10 hours. The systematic trends of XRD patterns shows that phase transformations form cubic structure to monoclinic structures occurred with the addition of Y2O3. The rate of pore were discussed with change of fraction of Nd2O3 and Y2O3. [ABSTRACT FROM AUTHOR]

This article presents a comprehensive economy‐wide material flow analysis of the Australian economy in 2019, examining the domestic extraction, trade, end‐of‐life flows, and recycling for all materials. The results highlight Australia's role as a natural resource supplier, with metals and fossil fuels being primary contributors. Through material flow analysis, we found that in 2019 Australia extracted 2587 Mt of natural resources, exported a substantial fraction (1459 Mt), and used 917 Mt to fulfill domestic needs. The recycling flows and circularity metrics are also explored, with an end‐of‐life recycling rate of 51.1% and an overall circularity rate of 5.1%. An additional assessment of Australia's consumption‐based material footprint highlights mobility and housing as the dominant material‐using sectors. These results contribute to understanding Australia's material consumption patterns, indicating significant reliance on foreign semifinished and finished products, and provide insights into the potential for enhancing economic circularity. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) is one of the promising metal fuels used in various applications such as flares, propellants, and rocket motor igniters. In particular, Mg is often used in the form of compounds or mixtures rather than being used alone. However, Mg is vulnerable to moisture, requiring an extra care in storage. Magnesium–Teflon–Viton (MTV), one of Mg-based mixtures, is expected to lose its combustion performance when exposed to moisture. The relative humidity (RH) conditions gave rise to the formation of an oxide film composed of magnesium oxide (MgO) and magnesium hydroxide (Mg(OH)2), while Mg(OH)2 was decomposed into MgO during the melting of polytetrafluoroethylene (Teflon). The dry conditions resulted in the formation of an oxide film composed only of MgO, which did not affect the melting of Teflon as in the RH condition. Moreover, a high-temperature environment intended for accelerated aging disrupted both pre-ignition and subsequent thermal reaction of MTV. Thus, the present work identified the changes in the thermochemical characteristics of MTV and clarified the roles of heat and moisture during such hygrothermal aging. [ABSTRACT FROM AUTHOR]

Although shock experiments are traditionally performed in large facilities, tabletop experiments that provide convenient high-throughput shock testing have been growing in importance. Here, we describe tabletop experiments using a shock compression microscope that features a pulsed 0–6 km/s laser flyer plate launcher and a photon Doppler velocimeter. We also describe methods to mass-produce flyer plates and targets to achieve high throughput. We explain how to condition a laser beam to launch flyers that provide reproducible short-rise time impacts with minimal tilt, and we present a number of applications including measuring shock propagation in nanoporous media, a simple way to describe shock wave energy absorption, the use of photoemissive probes such as organic dyes or quantum dots to study shocked inhomogeneous media, the development of an apparatus to measure optical absorption in shocked media, methods to study and measure the temperature of shocked energetic materials in the form of plastic-bonded explosives and in a form that allows us to observe hot spots in real time, and studies of the shocked interface between a metal fuel and a ceramic oxidizer. Finally, a brief perspective is presented describing new possibilities for future research of a diverse set of applications including the chemistry of shocked water and biological systems, dense plasmas, and the use of laser-launched flyer plates as surrogates for hypersonic vehicles. [ABSTRACT FROM AUTHOR]

This study extensively examined the impact of aluminium oxide (Al2O3) and titanium dioxide (TiO2) nanoparticles addition in the biodiesel fuel derived from Guizotiaabyssinica (L.) oil. The assessment of fuel blends, which were created by combining nanoparticles and biodiesel was conducted using energy, exergy, and sustainability indices. The highest recorded power output of 2.81 kW was observed for the GAB20A engine operating at 1800 rpm. The experimental results revealed that the GAB20A exhibited the lowest fuel consumption, with a recorded value of 203 g/kWh, when operated at 1600 rpm among all the tested blend fuels. The blend GAB20A exhibited the highest level of energy efficiency at 1600 rpm of 29.5%, as determined by the study. Simultaneously, it was observed that GAB20 exhibited the lowest energy efficiency at 1200 rpm among all the blend fuels at 25%. The emission levels of nitrogen oxides (NOx) and carbon monoxide (CO) were observed to be quite low, although a little rise in carbon dioxide (CO2) was detected. For validation of results the artificial neural network (ANN) was used and an average of 1.703% difference in energy efficiency, 2.246% decrease in exergy efficiency, and 1.416% difference in sustainability index was found. [ABSTRACT FROM AUTHOR]

Nowadays we are gradually transitioning from fossil to renewable energy in our energy consumption, but the green electricity, represented by solar and wind power, is highly fluctuating and difficult to use efficiently. Hydrogen production from electrolysis of water is currently an important pathway to consume green electricity, yet hydrogen still faces difficulties in large – scale long – term storage. Subsequently, a new pathway for the efficient use of renewable energy has been proposed: powering by renewable energy – preparing metal by electrolysis – heating by metal combustion. Metals are easy to store, and transport and its market is large. This makes it possible to realize the large – scale long – term storage of fluctuating renewable energy. In this new technical route, metal combustion is a crucial element. This work reviews the combustion models of iron and aluminum as fuels, and discusses their combustion characteristics under different particle sizes and microgravity conditions, as well as the flame propagation process. We hope that our work will benefit the development of this field. [ABSTRACT FROM AUTHOR]

Metal (aluminum and boron) based energetic materials have been wildly applied in various fields including aerospace, explosives and micro-devices due to their high energy density. Unfortunately, the low combustion efficiency and reactivity of metal fuels, especially boron (B), severely limit their practical applications. Herein, multi-component 3D microspheres of HMX/B/Al/PTFE (HBA) have been designed and successfully prepared by emulsion and solvent evaporation method to achieve superior energy and combustion reactivity. The reactivity and energy output of HBA are systematically measured by ignitionburning test, constant-volume explosion vessel system and bomb calorimetry. Due to the increased interfacial contact and reaction area, HBA shows higher flame propagation rate, faster pressurization rate and larger combustion heat of 29.95 cm/s, 1077 kPa/s, and 6164.43 J/g, which is 1.5 times, 3.5 times, and 1.03 times of the physical mixed counterpart (HBA-P). Meanwhile, HBA also shows enhanced energy output and reactivity than 3D microspheres of HMX/B/PTFE (HB) resulting from the high reactivity of Al. The reaction mechanism of 3D microspheres is comprehensively investigated through combustion emission spectral and thermal analysis (TG-DSC-MS). The superior reactivity and energy of HBA originate from the surface etching of fluorine to the inert shell (Al2O3 and B2O3) and the initiation effect of Al to B. This work offers a promising approach to design and prepare high-performance energetic materials for the practical applications. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR) is the key reaction in metal air and fuel cells. Among the catalysts that promote ORR, carbon‐based metal‐free catalysts are getting more attention because of their maximum atom utilization, effective active sites and satisfactory catalytic activity and stability. However, the pyrolysis synthesis of these carbons resulted in disordered porosities and uncontrolled catalytic sites, which hindered us in realizing the catalysts' design, the optimization of catalyst performance and the elucidation of structure–property relationship at the molecular level. Covalent organic frameworks (COFs) constructed with designable building blocks have been employed as metal‐free electrocatalysts for the ORR due to their controlled skeletons, tailored pores size and environments, as well as well‐defined location and kinds of catalytic sites. In this Concept article, the development of metal‐free COFs for the ORR is summarized, and different strategies including skeletons regulation, linkages engineering and edge‐sites modulation to improve the catalytic selectivity and activity are discussed. Furthermore, this Concept provides prospectives for designing and constructing powerful electrocatalysts based on the catalytic COFs. [ABSTRACT FROM AUTHOR]

Replacing the precious metal catalysts with low-cost, efficient and stable catalysts for oxygen reduction reaction (ORR) is necessary to solve the challenge of sluggish reaction kinetics. Commercial SiC and aniline were used as a precursor and nitrogen source to prepare a series of nitrogen-doped SiC electrocatalysts (N-SiC) by a facile pyrolysis method at different temperature (800–1100 °C) under nitrogen atmosphere. Among four N-SiC samples, N-SiC-1000 possesses the highest surface area, uniform nanorod morphology, highest nitrogen content, and positively shifted binding energy. Based on these characteristics, the N-SiC-1000 catalyst demonstrates the best ORR catalytic activity manifested by relatively positive onset potential of 1.01 V, half-wave potential (0.87 V) and highest current density (5.38 mA cm−2 at 0.4 V), which is comparable to that of Pt/C, and has significantly better stability and outstanding methanol tolerance than that of Pt/C. The number of electrons transferred of N-SiC-1000 for ORR process is ∼3.97, indicating a 4-electron reaction pathway. These results show that N-SiC-1000 is a low-cost, efficient and stable ORR catalyst and can be used as a substitute for precious metal catalyst in fuel cells application. Commercial SiC and aniline were used as a precursor and nitrogen source to prepare nitrogen-doped SiC electrocatalysts (N-SiC) by a facile pyrolysis method at different temperature. N-SiC-1000 possesses the highest surface area, uniform nanorod morphology, highest nitrogen content, and positively shifted binding energy. N-SiC-1000 catalyst demonstrated the best ORR catalytic activity, significantly better stability and outstanding methanol tolerance. [Display omitted] • N-SiC was prepared by a pyrolysis method at different temperature. • The composition, morphology, and surface area of N-SiC can be controlled by temperature. • The n value of N-SiC-1000 for ORR process is ∼3.97, indicating a 4-e pathway. [ABSTRACT FROM AUTHOR]

The paper presents an assessment of the effect caused by technological uncertainties on keff using the example of the test problem for a MET1000 fast sodium reactor with metal fuel. It is proposed to perform this assessment using nuclear sensitivity factors by random sampling or direct perturbation without requiring multiple calculations. The TSUNAMI-3D module of the SCALE program was used to analyze the sensitivity to nuclear data uncertainty. The obtained constant and technological uncertainties based on ENDF/B VII.1 equal 1.15 and 0.6%, respectively. The result was verified using direct perturbation. It is shown that a significant proportion of the technological uncertainties can be determined within the framework of the proposed evaluation method. [ABSTRACT FROM AUTHOR]

Metallized gel propellants with high metal content hold significant potential for enhancing the energy properties of hydrocarbon fuels. However, achieving an optimal balance between storage stability and atomization characteristics poses a significant challenge. In this study, we successfully synthesized metallized gel propellants that exhibit exceptional stability and remarkable shear-thinning properties by utilizing cooperative hydrogen bonding between polymer octanoyl cellulose and the small Thixatrol ST molecule. Through meticulous mixture design and formulation optimization, the metallized gel propellants demonstrated noteworthy characteristics, including a high calorific value of 48.48 MJ/kg, an impressive dynamic stability index of 89.12%, a surface tension of 23.21 mN/m, and sustained stability for at least six months under resting conditions. The metallized gel propellant, containing 50 wt% boron particles, exhibited a density 1.54 times higher than pure kerosene, meeting the requirements for enhancing specific impulse in rocket and ramjet engines. Moreover, optimized samples with varying boron concentrations were evaluated for their rheological properties and atomization behavior. The results revealed that the inclusion of boron particles increased the viscosity of the metallized gels. Consequently, the sample with 50 wt% boron exhibited modified viscosity-flow behavior, resulting in the formation of larger gel droplets during atomization. Finally, the metallized gel propellant demonstrated successful ignition in ramjet engine experiments. We anticipate that the cooperative hydrogen bonding between the polymer and small molecule will pave the way for the development of high-content metallized gel propellants with exceptional stability and superior shear thinning performance. [Display omitted] • Cooperative hydrogen-bonding between octanoyl cellulose and Thixatrol ST can be formed. • Mixture design was used to optimize calorific value, stability, and surface tension of propellant. • Rheology and atomization of metallized gels with boron content was investigated. • Metallized gels can be ignited in the ramjet engine experiment. [ABSTRACT FROM AUTHOR]

The combustion process of porous spherical titanium particles with diameters in the range of 100-400 μm was studied in free fall in air (as single particles), and in composite propellant (as metallic fuel). The particles burning times in air at atmospheric pressure were determined by video recording. Twelve composite propellant containing 60% AP of sieve fraction 180-250 μm, 20% energetic binder, and 20% titanium powder of various size and type (with porous particles and with rolled in ball mill pseudospherical particles) were studied. The propellant burning rate and the agglomeration parameters were determined at pressures of 0.35 MPa in nitrogen and at 0.1 MPa in air. It was established that the smallest agglomerates are formed when titanium powders of the smallest dimensions are used. [ABSTRACT FROM AUTHOR]

Laser micro-thrust technology is a type of propulsion that uses a laser beam to ablate a propellant such as a metal or plastic. The ablated material is expelled out the back of the spacecraft, generating thrust. The technology has the advantages of high control precision, high thrust–power ratios, and excellent performances, and it has played an important role in the field of micro-propulsion. In this study, a solid propellant laser micro-thruster was developed and then applied for the attitude control of satellites during on-orbit tests. The micro-thruster had a volume of 0.5 U, a weight of 440 g, and a thrust range of 10 μN–0.6 mN. The propellant, 87% glycidyl azide polymer (GAP) + 10% ammonium perchlorate (AP) + 3% carbon nano-powder, was supplied via a double-layer belt, and the average power was less than 10 W. We present the development of the laser micro-thruster, as well as the results regarding the thruster propulsion performance. The thruster was launched into orbit on 27 February 2022 with the Chuangxin Leishen Satellite developed by Spacety. The on-orbit test of the thruster for satellite attitude control was carried out. The thruster was successfully fired in space and played an obvious role in the attitude control of the satellite. The experimental results show that the thrust is about 315 μN. [ABSTRACT FROM AUTHOR]

U-10 wt.% Zr (U-10Zr) metallic fuel is the leading candidate for next-generation sodium-cooled fast reactors. Porosity is one of the most important factors that impacts the performance of U-10Zr metallic fuel. The pores generated by the fission gas accumulation can lead to changes in thermal conductivity, fuel swelling, Fuel-Cladding Chemical Interaction (FCCI) and Fuel-Cladding Mechanical Interaction (FCMI). Therefore, it is crucial to accurately segment and analyze porosity to understand the U-10Zr fuel system to design future fast reactors. To address the above issues, we introduce a workflow to process and analyze multi-source Scanning Electron Microscope (SEM) image data. Moreover, an encoder-decoder-based, deep fully convolutional network is proposed to segment pores accurately by integrating the residual unit and the densely-connected units. Two SEM 250 × field of view image datasets with different formats are utilized to evaluate the new proposed model's performance. Sufficient comparison results demonstrate that our method quantitatively outperforms two popular deep fully convolutional networks. Furthermore, we conducted experiments on the third SEM 2500 × field of view image dataset, and the transfer learning results show the potential capability to transfer the knowledge from low-magnification images to high-magnification images. Finally, we use a pre-trained network to predict the pores of SEM images in the whole cross-sectional image and obtain quantitative porosity analysis. Our findings will guide the SEM microscopy data collection efficiently, provide a mechanistic understanding of the U-10Zr fuel system and bridge the gap between advanced characterization to fuel system design. [ABSTRACT FROM AUTHOR]

Gaseous fission products from nuclear fission reactions tend to form fission gas bubbles of various shapes and sizes inside nuclear fuel. The behavior of fission gas bubbles dictates nuclear fuel performances, such as fission gas release, grain growth, swelling, and fuel cladding mechanical interaction. Although mechanical understanding of the overall evolution behavior of fission gas bubbles is well known, lacking the quantitative data and high-level correlation between burnup/temperature and microstructure evolution blocks the development of predictive models and reduces the possibility of accelerating the qualification for new fuel forms. Historical characterization of fission gas bubbles in irradiated nuclear fuel relied on a simple threshold method working on low-resolution optical microscopy images. Advanced characterization of fission gas bubbles using scanning electron microscopic images reveals unprecedented details and extensive morphological data, which strains the effectiveness of conventional methods. This paper proposes a hybrid framework, based on digital image processing and deep learning models, to efficiently detect and classify fission gas bubbles from scanning electron microscopic images. The developed bubble annotation tool used a multitask deep learning network that integrates U-Net and ResNet to accomplish instance-level bubble segmentation. With limited annotated data, the model achieves a recall ratio of more than 90%, a leap forward compared to the threshold method. The model has the capability to identify fission gas bubbles with and without lanthanides to better understand the movement of lanthanide fission products and fuel cladding chemical interaction. Lastly, the deep learning model is versatile and applicable to the micro-structure segmentation of similar materials. [ABSTRACT FROM AUTHOR]

We study the effect of various accidental events on reactivity during the severe stage of an accident using the STEPAN-T 3D-program, developed specifically for simulating an accident with a complete blackout of the RBMK. The maximum and average temperatures of graphite and fuel and the temperatures of metal structures of the lower support and shielding (OR circuit) are presented, as well as the chronology of destruction of the core elements before the onset of the fuel destruction. The effect of reactivity from graphite heating is shown. The effects of reactivity from the melting of aluminum sleeves of cluster control rods (CCRs) are considered, as well as the shells of shortened control rods (SCRs) and emergency rods (ERs). An analysis is made of the scenario where, owing to removal of aluminum sleeves of the CCR rods, the absorbing elements, losing their distance, form a dense bundle. The scenario of the breakage of belts by the servo drive of the CCR rods and the fall of absorbing elements under the core of the reactor is considered, as well as the impact of this incident on reactivity. In addition, we estimated the effects of the formation of "fuel columns" on reactivity resulting from the destruction of the fuel assemblies (FAs), along with the escape effect of fission products and erbium. [ABSTRACT FROM AUTHOR]

One of the main problems of fast reactors with sodium coolant is its high chemical activity in interaction with water and air. This requires complex safety systems, fire extinguishing, and diagnostics and complicates the design of steam generators and pipelines. The use of Na–Tl eutectic as a coolant for the first and intermediate circuits of a modular fast neutron reactor can alleviate this problem. Sodium–thallium eutectic (92.9%Na–7.1%Tl) has a much lower chemical activity than pure sodium and prevents or extinguishes its ignition by forming an inert surface layer. Also, this coolant has a higher boiling point and a lower melting point in comparison with sodium. The introduction of thallium into the coolant can change the neutron spectrum in the core and the neutronic characteristics of the reactor. In this paper, the effect of replacement of Na coolant with the Na–Tl eutectic on the neutronic characteristics of a modular fast reactor with metal fuel is studied. In addition, the influence of possible changes in the isotopic composition of thallium is studied. The activation of thallium isotopes in the coolant is simulated and their contribution to the gamma-radiation source is investigated. [ABSTRACT FROM AUTHOR]

Using the BISON fuel-performance code, simulations were conducted of an automated process to read initial and operating conditions from the Pacific Northwest National Laboratory (PNNL) database and reports, which contain metallic-fuel data from the Fast Flux Test Facility (FFTF) MFF Experiments. This work builds on previous modeling efforts involving 1977 EBR-II metallic fuel pins from experiments. Coupling the FFTF PNNL reports to BISON allowed for all 338 pins from MFF-3 and MFF-5 campaigns to be simulated. Each BISON simulation contains unique power and flux histories, axial power and flux profiles, and coolant-channel flow rates. Fission-gas release (FGR), fuel axial swelling, cladding profilometry, and burnup were all simulated in BISON and compared to available post-irradiation examination (PIE) data. Cladding profilometry, FGR, and fuel axial swelling simulation results for full-length MFF metallic pins were found to be in agreement with PIE measurements using FFTF physics and models used previously for EBR-II simulations. The main two peaks observed within the cladding profilometry were able to be simulated, with fuel-cladding mechanical interaction (FCMI), fuel-cladding chemical interaction (FCCI), and thermal and irradiation-induced creep being the cause. A U-Pu-Zr hot-pressing model was included in this work to allow pore collapse within the fuel matrix. This allowed better agreement between BISON-simulated cladding profilometry and PIE measurements for the peak caused by FCMI. This work shows that metallic fuel models used to accurately represent fuel performance for smaller EBR-II pins may be used for full-length metallic fuel, such as FFTF MFF assemblies and the Versatile Test Reactor (VTR). As new material models and PIE measurements become available, FFTF MFF assessment cases will be reassessed to further BISON model development. [ABSTRACT FROM AUTHOR]