Use Of Reactor Research Articles

Numerical Examination of a Squeezing Casson Hybrid Nanofluid Flow Considering Thermophoretic and Internal Heating Mechanisms

One of the main areas of study in the field is increasingly the flow of non-Newtonian fluids. These liquids find extensive use in nuclear reactors, food processing, paint and adhesives, drilling rigs, and cooling systems, among other industrial and engineering domains. However, hybrid nanofluids are crucial to the process of heat transfer. Considering this, this study investigates the motion of a Casson hybrid nanofluid squeezing flow between two parallel plates under the influence of a heat source and thermophoretic particle deposition. The Runge–Kutta–Fehlberg fourth–fifth-order approach is utilized to numerically solve the ordinary differential equations derived from the partial differential equations governing fluid flow, by utilizing suitable similarity variables. The diagrams show how several important parameters affect fluid profiles both with and without the Casson parameter. These figures demonstrate how fluid velocity increases as the local porosity parameter increases. When the heat source/sink parameter is increased, thermal dispersal increases, and when the thermophoretic parameter is increased, the concentration profile increases.

Performance evaluation and optimization of a suspension-type reactor for use in heterogeneous catalytic ozonation

Packed fixed-bed reactors are traditionally used for heterogeneous catalytic ozonation. However, a high solid-to-liquid requirement, poor ozone dissolution, ineffective utilization of catalyst surface area, and production of large amounts of catalyst waste impede application of such reactors. In this study, we designed a suspension catalytic ozonation reactor and compared the performance of this reactor with that of a traditional fixed-bed catalytic ozonation reactor employing oxalic acid (OA) as the target contaminant. Our results showed that total O3 dissolved into the suspension reactor (117–134 mg.L−1) was much higher compared to that measured in the fixed-bed reactor (53 mg.L−1) due to a higher O3(g) interphase mass transfer rate in the suspension reactor. In accordance with the higher O3(g) interphase mass transfer, we observed a much higher proportional OA removal (32 %) compared to that achieved in the fixed-bed reactor (10%) employing an Fe-oxide catalyst supported on Al2O3 (Fe-oxide@Al2O3) in both reactors. Use of a double-layered Cu-Al hydroxide (Cu-Al LDHs) catalyst in the suspension reactor further enhanced the performance with nearly 90 % OA removal observed. Given the superior performance of the suspension reactor, we investigated the impact of operating conditions (catalyst dosage, hydraulic retention time and ozone dosage) employing Cu-Al LDHs as the catalyst. We also developed a mathematical kinetic model to describe the performance of the suspension reactor and, through use of the kinetic model, showed that O3(g) interphase transfer rate was the rate-limiting step in OA removal. Thus, improvement in ozone gas diffuser design is required to improve the performance of the suspension reactor. Overall, the present study demonstrated that suspension reactors were more effective than fixed-bed reactors for oxidation of surface-active organic compounds such as OA due to the higher ozone interphase mass transfer rate and effective utilization of the catalyst surface area that can be achieved. As such, further research on suspension reactor design and development of catalysts suitable for use in suspension reactors should facilitate large-scale application of catalytic ozonation processes by the wastewater treatment industry.

Characteristics of granule solidification in gas atomization of molten beryllium

Experimental and analytical studies on gas atomization of the molten beryllium and the production of beryllium granules are presented. The impact of various factors, including the choice of gas (nitrogen or helium), the cooling gas flow rate (ranging from 300 to 650 m/s), melt temperature, and droplet size (<500 µm), on the cooling rate and granule properties, is demonstrated. It has been determined that the solidification of beryllium granules can occur through two distinct mechanisms depending on the atomization process. These mechanisms include crystallization and amorphization (glass transition). When beryllium melt is atomized with nitrogen, granules with diameters less than 100 µm solidify via the amorphization mechanism (glass transition), while those with diameters exceeding 300 µm solidify through crystallization. In such cases, a portion of granules with sizes ranging from 100 to 300 µm undergoes a mixed mechanism solidification. In this process, the surface becomes amorphous, while the central part crystallizes, resulting in the formation of a “shell” on the surface, marking the transition from the glass transition mechanism to the crystallization mechanism. The thickness of this “shell” depends on the granule diameter, measuring 10–15 µm for 300 µm granules and 20–25 µm for 100 µm granules. The findings from this research align well with the hypothesis of a glass-crystalline mechanism of beryllium granule solidification, which leads to their separation at the interfacial boundary. Such solidification through a mixed mechanism results in the creation of a removable “crust” on the granule, which is typically more contaminated with impurities. Understanding this effect opens up possibilities for practical applications in the production of specialized materials from beryllium. The ability to separate the “crust” from the “core” provides the conditions for obtaining specialized sintered beryllium grades suitable for use in nuclear reactors and foil production, where a beryllium microstructure with “clean” boundaries is essential.

Exploring critical behavioral differences in physical, structural, and nuclear radiation attenuation properties of produced High Entropy Alloy (HEA) and Refractory-High Entropy Alloy (RHEA) samples

Refractory-High entropy alloys (RHEAs) are known for their exceptional mechanical and radiation-resistant properties, making them promising materials for use in nuclear reactors. Their high entropy composition, which consists of multiple elements in roughly equal proportions, can create a stable microstructure that withstands high levels of radiation damage. The objective of this work is to further our comprehension of the unique behavioral, physical, structural, and nuclear radiation attenuation characteristics shown by High-Entropy Alloys (HEA) and Refractory-High entropy alloy (RHEA) materials. Accordingly, two high entropy alloy (HEA) samples through two different compositions were produced. The first composition under consideration is the typical high-entropy alloy (HEA) defined as MnCrFeNiCoMo0.5. The second composition under consideration is a refractory high entropy alloy (RHEA) characterized by the following elemental composition: TiZrNbHfVTa0.1. SEM and EDX analyses were conducted in terms of determining their physical and structural attributes. Next, a133Ba radioisotope together with a HPGe detector were utilized for gamma-ray transmission experiments. Finally, a241Am/Be source and a gas proportional detector were used for neutron absorption experiments for HEA and RHEA samples. The alloy structures displayed a unique degree of uniformity. Throughout the RHEA phase, the incorporation of refractory elements did not provide any discernible adverse impacts on the physical stability. The counting spectrum provided a clear explanation of the gamma ray absorption features shown by the RHEA (R) sample, highlighting its exceptional absorption properties. Regarding the absorption properties of neutrons, it was observed that RHEA had a comparatively reduced amount of absorption. Therefore, it can be concluded that the basic structure of RHEA grants it superior gamma-ray attenuation qualities compared to HEA. It can be concluded that RHEA demonstrates superior applicability as a material in comparison to HEA, especially in situations involving the use of fuel rods, where maintaining of neutron quantity has paramount importance for achieving optimum neutron activation.

Obtaining SiC Fibers–PyC interfacial properties through push-out FEM Models

Silicon carbide (SiC) has attractive properties for use in nuclear reactors. However, it is hampered by inherent brittleness that is overcome through a fiber-reinforced composite. A finite element model based on cohesive zone contact coupled to Coulomb friction is proposed to simulate the push-out response of isolated fibers in SiC/PyC fiber-reinforced composites. The model reproduces the measurements obtained during push-out experiments of isolated fibers in different configurations and predicts interfacial failure between the PyC interphase and fiber. The brittle properties predicted coincide with literature indicating that fiber–PyC interface could prevent the crack propagation through the fiber, fulfilling the function of the structure.

Effect of tungsten doping on the irradiation resistance of FeCrV-based refractory medium entropy alloy for potential nuclear applications

Given the increasing demand for energy and the rising cost of fossil fuels, the development of nuclear fission and fusion reactors has become a key priority. Recently, High Entropy Alloys (HEAs) and Medium Entropy Alloys (MEAs) have emerged as promising materials for use in nuclear reactors due to their unique properties, which include significant lattice distortion, high configurational entropy, reduced diffusivity, and the cocktail effect. In this study, we designed and analysed a series of FeCrV-based Refractory Medium-entropy Alloys (RMEAs) as structural materials in fusion reactors, using Density Functional Theory. By calculating the empirical parameters, we have verified the solid solution's structure stability of the FeCrV-based RMEA. We examined the mechanical, electronic, and irradiation resistance properties of these alloys and found that the incorporation of tungsten dopants could enhance both the mechanical properties and irradiation resistance of the materials, with the optimal doping level being approximately 8% of Tungsten. Furthermore, electronic structure calculations were performed to elucidate the underlying mechanisms. This knowledge can guide the development of new HEA/MEA materials for use in nuclear reactors.

Investigation of boron element and its use in nuclear reactors

Within the scope of this study, the importance of boron element which has the largest reserve in Turkey and boron carbide, the most important material produced from boron, in nuclear technology has been emphasized. B4C is the basic material of control rods used to control the fission rate in nuclear reactors and is used in many nuclear reactors. The high neutron absorbing capacity of B4C material makes this material very useful. In order to examine B4C used in nuclear technology, mass attenuation coefficient (MAC) and lineer attenuation coefficient (LAC) values, which are two important radiation parameters, were examined through open access Photon Protection and Dosimetry (PSD) software which is at phy-x.net/PSD. The results obtained were compatible with the literature.

Blanket Cooling of a Fusion Reactor

Nuclear fusion is the gateway to a whole new paradigm of energy and is a strong candidate for the decarbonization of electricity generation on a global scale. With recent developments in high-temperature super-conducting magnets, the race is on to develop sub-systems which will support a commercially viable fusion reactor for use as a thermal power plant. The fusion of lighter elements creates an enormous amount of heat which must be transferred away from the reactor core. These intense conditions require novel approaches to efficiently transfer very high heat loads into useable thermal energy without compromising the structural integrity of the reactor core and the surrounding components. This report outlines the concept of a fundamental approach to solve the heat transfer problem as proposed by Commonwealth Fusion System’s design for a fusion reactor. A literature review was conducted for other applications that could serve as inspirations, as well as material properties and machining methods for the proposed power exhaust system. A dive into the theoretical thermodynamic and fluid dynamic characteristics of plate heat exchangers and finned surfaces was conducted from a fundamental perspective. A laminar flow regime was studied for the purpose of setting the floor for energy needed to pump coolant while simultaneously representing the least favorable heat transfer regime between a solid surface and a fluid. The results served as a basis for dimensioning and executing numerical simulations as a means for a first look into a solution of this heat transfer problem. The results were compared with the theoretical conclusions and judged based on constraints of the system. Recommendations were made for the continued development of a corresponding system.

Hybridised production of technetium-99m and technetium-101 with fluorine-18 on a low-energy biomedical cyclotron

New modes of production and supply of short-lived radioisotopes using accelerators are becoming attractive alternatives to the use of nuclear reactors. In this study, the use of a compact accelerator neutron source (CANS) was implemented to explore the production of 99mTc and 101Tc. Irradiations were performed with neutrons generated from a 16.5 MeV cyclotron utilising the 18O(p, n)18F reaction during routine 18F-fluorodeoxyglucose (FDG) production in a commercial radiopharmacy. Natural molybdenum targets in metal form were employed for the production of several Tc isotopes interest via (n, γ) reactions on 98Mo and 100Mo. The production of 99mTc and 101Tc under these conditions is considered and discussed.

Micromechanical aspects of deformation and failure of advanced Iron-Chromium-Aluminum alloys

This work investigates the micromechanical deformation and failure mechanisms of advanced FeCrAl alloys developed for use in nuclear reactors as cladding material. Three different FeCrAl alloys (82-X)Fe-13Cr-5Al-X (X=Nb, TiC, 0 for base alloy) were investigated both in their as-received and welded states. In-situ neutron diffraction with simultaneous digital image correlation was used to determine micromechanical deformation mechanisms not only as a function of elemental composition but also as a condition of state (as-received vs. welded). Ex-situ X-ray computed tomography was used on as-deformed samples to help determine the failure mechanisms and void initiation strains.

Influence of weave architecture on mechanical response of SiCf-SiCm tubular composites

Due to their high resistance to radiation damage and elevated temperature, silicon carbide fiber-reinforced, silicon carbide matrix composites (SiCf-SiCm) are identified as potential cladding structures for use in nuclear reactors. In this study, four composite architectures with varying ply numbers along the thickness direction and different biaxial or triaxial plain weave orientations at either 45° or 60°, were systematically evaluated under various stress states to assess the influence of weave architecture on mechanical performance. Experiments were conducted on SiCf-SiCm composite tubes under tensile hoop, axial compression, and rotating flexural loading to evaluate the mechanical response and investigate the failure modes using high-speed imaging and digital image correlation (DIC) techniques. It was found that for tensile hoop burst and flexural loading, the braiding angle had the most significant influence on the strength of the composite, whereas the effect of fiber angle was more limited for compression testing. Under axial compression a unique failure mode where a microcrack nucleates and grows only to a length equal to the thickness of a single yarn was identified. This crack growth behavior is reflected as periodic oscillations in the load-displacement response. For both axial and hoop loading, regardless of weave angle and number of plies, failure always initiated parallel to the tube axis in a single yarn and the cumulative interaction of these microcracks lead to either axial burst or fracture at an angle to the tube axis along a yarn. These results point to the importance of customizing the design of tube architecture for enhanced performance in specified nuclear applications.

Designing a Reactor for Use in High Voltage Power Systems and Performing Experimental and Simulation Analysis

Today, magnetically controlled shunt reactors are widely used in solving power quality problems. These reactors are designed to reduce system reactive power, control high super/special high voltage grid voltage, suppress power frequency, regulate overvoltage, eliminate generator excitation, dynamically compensate transmission line power charge, suppress secondary arc current, suppress system resonance. By using suitably designed silica plate core reactors at the input of the frequency converters in the electrical distribution system, the level of harmonic currents drawn from the electrical power distribution system can be reduced to certain rates. The core material, the air-gapped nature of the reactor core, and the sizing of the reactor have a great influence on the harmonic level of the current and its ability to reduce losses in the reactor. In this study, three reactors with different core materials and different air gap gaps are designed for a certain voltage value. Parametric analysis of the reactors designed to see the changes in inductance values depending on the load level has been made both theoretically and experimentally and using the Finite Element Method. As a result of the analysis, the inductance stability, losses and compliance of the reactors with the standards are presented. The reactor's magnetic circuit is modeled with ANSYS@Maxwell, realizing a solution based on this method. The magnetic circuit is simulated to see the behavior of the reactor. In addition, real-time verification of the designed alternating current reactor has been made. Optimum design was obtained by using different core materials and different core air-gaped tested experimentally. The effect of the air gap distance in the core on the magnetic field and inductance value was also obtained.

Cerium Catalysts in Steam-Assisted Pyrolysis of -Dodecane for Hypersonic Thermal Management

Cerium was used as a catalyst for cracking in a cylindrical packed bed reactor, alone and then in conjunction with a commercially available platinum catalyst. The objective was to examine its suitability for use in potential thermal management systems. Cracking product distribution, fuel endotherm, and carbon deposition results for the cerium catalyst were compared to those reported previously for the commercial platinum catalyst in a similar packed bed reactor configuration. For some experiments, water was added to the fuel for steam assistance to the pyrolysis reactions in order to examine the effect of water on carbon production and endotherm. The cerium catalysts outperformed the platinum catalyst in terms of both increased endotherm and decreased carbon deposition. Steam assistance proved beneficial in decreasing carbon deposition, although at the cost of decreased endotherm. No appreciable product selectivity was observed for steam assistance with either catalyst. Finally, the overall reaction constant for each catalyst-steam addition case was compared to dodecane conversion in order to determine a relationship that can be applied in designing a reactor for use in a thermal management system.

Determination of Thermal Expansion, Defect Formation Energy, and Defect-Induced Strain of α-U Via ab Initio Molecular Dynamics

Uranium (U) is often alloyed with molybdenum (Mo) or zirconium (Zr) in order to stabilize its high-temperature body-centered cubic phase for use in nuclear reactors. However, in all metallic fuel forms, the α phase of U remains in some fraction. This phase decomposition due to temperature or compositional variance can play an outsized role on fuel performance and microstructural evolution. Relatively little is known about fundamental point defect properties in α-U at non-zero temperatures, from either computational or experimental studies. This work performs the first thorough evaluation of the α phase of U via ab initio molecular dynamics (AIMD). A number of thermophysical properties are calculated as a function of temperature, including equilibrium lattice parameters, thermal expansion, and heat capacity. These results indicate a two-region behavior, with the transition at 400 K. The thermal expansion/contraction in the a/b direction occurs rapidly from 100 up to 400 K, after which a more linear and gradual change in the lattice constant takes place. The volumetric expansion matches experiments quantitatively, but the individual lattice constant expansion only matches experiments qualitatively. Point defect formation energies and induced lattice strains are also determined as a function of temperature, providing insight on defect populations and the fundamentals of irradiation growth in α-U. Interstitials induce significantly more strain than vacancies, and the nature of that strain is highly dependent on the individual lattice directions. The direction of point defect-induced lattice strain is contrary to the irradiation growth behavior of α-U. This work shows that isolated point defects cannot be the primary driving force responsible for the significant irradiation-induced growth of α-U observed experimentally.

The future of nuclear energy in India: Evidence from a nationwide survey

Extant research has demonstrated that public support (or lack thereof) is a primary driver for the expansion (or decline) of the use of nuclear reactors as a significant source of energy. This study uses a national survey to explore the dynamics of public support for nuclear energy in India, which remains understudied. In doing so, the study also builds on existing research by analyzing key factors that have been shown to have an influence on public opinion about nuclear energy in other contexts such as the US, UK, South Korea, and China. Survey results indicate that there is substantial support for nuclear energy amongst the Indian public and that public perceptions about the benefits of nuclear energy outweigh the potential risks. Results also show that concerns about energy security and climate change correlate with support for nuclear energy, suggesting that members of the Indian public are willing to accept possible risks of nuclear energy to realize the benefits of energy security and, to a lesser extent, climate change mitigation.

Precipitation in proton- and ion-irradiated Alloy 625 Plus

• Ion irradiation at dose rates above 10 -4 dpa/s at 300 °C causes disordering and dissolution of precipitates. • Non-equilibrium steady state nanoscale γ’ and γ” microstructures develop under proton irradiations at 300 and 400 °C. • The Ni 3 Si and Pt 2 Mo-type ordered precipitates also formed under proton irradiations at 300 and 400 °C. • γ″ phase formation lowers the matrix Ni/Cr ratio and favors Pt 2 Mo-type phase formation. Alloy 625 Plus is a commercial Ni-based alloy proposed as a candidate structural material for use in nuclear reactors. To clarify its microstructural evolution under relevant irradiation service conditions, we performed long term thermal aging, as well as proton and ion irradiations at ~300 and 400°C. While cascade mixing dominates during ion irradiation, diffusional processes allow the γ″, γ′, Ni 3 Si, and Pt 2 Mo-type ordered phases to form under proton irradiation. Moreover, comparison between solution treated and aged samples revealed steady state nanoscale patterning of the γ″ and γ′ phases and the dependence of the formation of the Pt 2 Mo-type phase on the precipitation of γ″.

Energy optimization of a Sulfur–Iodine thermochemical nuclear hydrogen production cycle

The use of nuclear reactors is a large studied possible solution for thermochemical water splitting cycles. Nevertheless, there are several problems that have to be solved. One of them is to increase the efficiency of the cycles. Hence, in this paper, a thermal energy optimization of a Sulfur–Iodine nuclear hydrogen production cycle was performed by means a heuristic method with the aim of minimizing the energy targets of the heat exchanger network at different minimum temperature differences. With this method, four different heat exchanger networks are proposed. A reduction of the energy requirements for cooling ranges between 58.9-59.8% and 52.6-53.3% heating, compared to the reference design with no heat exchanger network. With this reduction, the thermal efficiency of the cycle increased in about 10% in average compared to the reference efficiency. This improves the use of thermal energy of the cycle.

Ab initio molecular dynamics investigation of point defects in [formula omitted]-U

Uranium (U) is often alloyed with molybdenum (Mo) or zirconium (Zr) in order to stabilize the high-temperature body-centered cubic γ phase of uranium for use in nuclear reactors. However, relatively little experimental or computational investigation has centered on γ-U, largely due to the mechanical instability of this phase at room temperature. This is particularly problematic for density functional theory calculations that typically investigate 0 K properties. However, ab initio molecular dynamics (AIMD) allows for quantum mechanical-based calculations to be performed at non-zero temperatures. In this work, AIMD simulations are performed to calculate the equilibrium volume for the γ phase of U from 900 K to 1400 K. Utilizing the volume at each temperature, the bulk modulus, the radial distribution function, the interstitial and vacancy formation energies, and the diffusion coefficients are determined.

Electrochemical precipitation of neptunium with a micro electrochemical quartz crystal microbalance.

Microliter volumes are used in electrochemical detection and preconcentration of radionuclides to reduce the dose received by researchers and equipment. Unfortunately, there is a lack of analysis of radionuclides with coupled electrochemical techniques and microliter volume reactors. The goals of this work are 1) to develop a miniaturized micro-electrochemical quartz crystal microbalance (µeQCM) reactor for use in small volume (50-200 µL) electrogravimetric experiments and 2) to use this reactor to characterize the preconcentration of neptunium on carbon electrodes via electroprecipitation. We successfully deposited neptunium in the new µeQCM reactor and verified its operation. We found that preconcentration of neptunium on carbon coated electrodes was possible by chronoamperometry at -1.6 VAg/AgCl. The mass shift of the resulting precipitate was indicative of the amount of neptunium on the electrode, although the correlation between the mass increase and activity of the preconcentrated material was not linear. Neptunium precipitate reduced electron transfer to the solution as evidenced by the increase in charge transfer resistance compared to bare electrodes.

High-Temperature Nano-Indentation Creep of Reduced Activity High Entropy Alloys Based on 4-5-6 Elemental Palette.

There is a strong demand for materials with inherently high creep resistance in the harsh environment of next-generation nuclear reactors. High entropy alloys have drawn intense attention in this regard due to their excellent elevated temperature properties and irradiation resistance. Here, the time-dependent plastic deformation behavior of two refractory high entropy alloys was investigated, namely HfTaTiVZr and TaTiVWZr. These alloys are based on reduced activity metals from the 4-5-6 elemental palette that would allow easy post-service recycling after use in nuclear reactors. The creep behavior was investigated using nano-indentation over the temperature range of 298 K to 573 K under static and dynamic loads up to 5 N. Creep stress exponent for HfTaTiVZr and TaTiVWZr was found to be in the range of 20–140 and the activation volume was ~16–20b3, indicating dislocation dominated mechanism. The stress exponent increased with increasing indentation depth due to a higher density of dislocations and their entanglement at larger depth and the exponent decreased with increasing temperature due to thermally activated dislocations. Smaller creep displacement and higher activation energy for the two high entropy alloys indicate superior creep resistance compared to refractory pure metals like tungsten.