Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
13,938
result(s) for
"Gas reactors"
Sort by:
Review of Reactors with Potential Use in Thermochemical Energy Storage in Concentrated Solar Power Plants
The aim of this study is to perform a review of the state-of-the-art of the reactors available in the literature, which are used for solid–gas reactions or thermal decomposition processes around 1000 C that could be further implemented for thermochemical energy storage in CSP (concentrated solar power) plants, specifically for SPT (solar power tower) technology. Both direct and indirect systems can be implemented, with direct and closed systems being the most studied ones. Among direct and closed systems, the most used configuration is the stacked bed reactor, with the fixed bed reactor being the most frequent option. Out of all of the reactors studied, almost 70% are used for solid–gas chemical reactions. Few data are available regarding solar efficiency in most of the processes, and the available information indicates relatively low values. Chemical reaction efficiencies show better values, especially in the case of a fluidized bed reactor for solid–gas chemical reactions, and fixed bed and rotary reactors for thermal decompositions.
Journal Article
The Influence of High-Temperature Helium and the Amount of Revert Material on the Material Properties of Inconel 738
Nickel-based alloys are considered promising materials for primary circuits of high-temperature gas reactors (HTGRs), specifically for gas turbines. The primary helium (He) coolant in the gas-turbine-based HTGRs is expected to reach temperatures of up to 900 °C; therefore, the selected materials should adequately perform over a long service life at such an environment. A promising manufacturing method in the production of reactor components is precision casting, where the content of revert (recyclate) material in the alloy differs and can influence the material behavior. In our study, Inconel alloy 738 was manufactured by casting 50% and 100% of revert material and tested in HTGR conditions to examine the influence of helium coolant on the material’s properties. Tensile specimens were exposed at 900 °C for 1000 h in helium containing a specified amount of gaseous impurities. Scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), in combination with X-ray diffraction (XRD) and nano-, microhardness methods, were used for material characterization after performing the tensile tests at room temperature. The presence of three types of layers was observed: a thin layer formed by aluminum and chromium oxides on the surface; non-uniform surface oxides Ti3O5 with inner (Al,Cr)2O3; and the inner fine-grained Inconel Cr-enriched phase (approx. 10–20 µm below the surface), which can act as a protective surface layer. Mechanical properties of both revert materials decreased after exposure to HTGR conditions but did not show a significant difference as a result of the content of the revert material. The increase of nano-hardness in line profiles throughout the specimen’s cross-section was observed locally at the surface oxides and in the precipitates and grain boundaries. After exposure, Rp0.2 values decreased by 20% and 17.7%, and Rm values by 12.3% and 20.8% in samples with 50 and 100% revert content, respectively. Furthermore, a decrease in microhardness values (HV0.1) was detected by 4.98% in longitude and 5.80% in cross-section for samples with 50% revert material and by 3.85% in longitude and 7.86% in cross-section for samples with 100% revert material. It can be concluded that both revert materials have similar corrosion resistance in HTGR conditions. The presented results complement the knowledge about the degradation of alloys in the coolant environment of advanced gas-cooled reactors.
Journal Article
Advanced Structural Materials for Gas-Cooled Fast Reactors—A Review
This review summarizes the development of the Gas-Cooled Fast Reactor (GFR) concept from the early 1970s until now, focusing specifically on structural materials and advanced fuel cladding materials. Materials for future nuclear energy systems must operate under more extreme conditions than those in the current Gen II or Gen III systems. These conditions include higher temperatures, a higher displacement per atom, and more corrosive environments. This paper reviews previous GFR concepts in light of several promising candidate materials for the GFR system. It also reviews the recent development of nuclear power and its use in the peaceful exploration of space. The final section focuses on the development and testing of new advanced materials such as SiCf/SiC composites and high entropy alloys (HEA) for the construction and development of GFRs.
Journal Article
Selection of Planning Options of Electricity and Freshwater Cogeneration Method Based on High-Temperature Gas-Cooled Reactor
The lack of fresh water in the world has become a growing concern. As an open-source incremental technology for water resources, desalination has become an important method to solve the global water crisis. Based on the inherent safety, versatility, modularity, and advantages of high-temperature gas-cooled reactors, the Saudi Arabia desalination project is the relying background. This paper proposes a complete solution for the high-temperature gas-cooled reactor power and water coproduction project by selecting a combination of process-proven multi-effect distillation (MED) and reverse osmosis (RO). In the scheme, a tertiary circuit is designed for the isolation of radioactive entities. An innovative comparative analysis of the engineering investment and production costs of different desalination technologies, such as MED and RO, and a comparison of the investment estimates of the “thermal” and “membrane” methods for the production of 10,000 tonnes of fresh water per day are performed. The feasibility and energy efficiency of the multi-effect distillation–reverse osmosis (MED-RO) scheme are presented, demonstrating the feasibility and practicality of the above approach.
Journal Article
Assessment of design approximation impact on neutronic characteristics of a high-temperature gas-cooled reactor fuel assembly
A comparative study has been conducted to find out how design approximations and simulation methods of a prismatic-type fuel block of a high-temperature gas-cooled reactor (HTGR) may affect the calculation accuracy of neutronic characteristics of fuel assemblies. To study the impact, a detailed three-dimensional computational model of a typical fuel block including fuel compacts, burnable absorber compacts, and coolant passages was developed. Changes in neutronic characteristics in the process of fuel assembly irradiation were calculated. The burnup was analyzed based on the SCALE 6.2.4 software package using a calculation module implementing the Monte Carlo method with a multigroup library of cross-sections on the basis of ENDF/B-VII.1 files of assessed nuclear data and the ORIGEN burnup analysis module included in this package. Different ways of modeling fuel compacts and burnable absorber compacts have been considered: using a built-in tool (DOUBLEHET cell type), by specifying fuel particles in the graphite matrix, and their combination. The calculations were made using the 252-group library of constants except for the option in which fuel compacts and burnable absorber compacts were simulated explicitly by particles in the graphite matrix. In the latter case, a library with a pointwise (CE) representation of cross-sections was used. A series of calculations were also made to assess the way computational statistic parameters affect the results. The results confirm correct operation of the SCALE complex built-in tool, i.e. cells with the DOUBLEHET-type double heterogeneity, and its prospective use to calculate neutronic characteristics of HTGR fuel. The calculations have also shown that it is acceptable to model burnable absorber compacts both by setting a DOUBLEHET-type cell and explicitly by particles in the graphite matrix. In general, the calculation results for these options agree quite well, within 1-2%, with the direct calculation using the pointwise library of cross-sections. Based on the computational statistic parameters, it may be recommended to set at least 200,000 histories and the number of particles in a generation or the number of generations should be at least 250.
Journal Article
Computational Fluid Dynamics Modeling of Single Isothermal and Non-Isothermal Impinging Jets in a Scaled-Down High-Temperature Gas-Cooled Reactor Facility
In the current work, the flow characteristics of single isothermal and non-isothermal jets discharging into the upper plenum of a 1/16th scaled-down high-temperature gas-cooled reactor (HTGR) facility were studied. ANSYS Fluent simulations were carried out in the central plane of the jet water flow and the upper plenum for different Reynolds numbers (Re) ranging from 3413 to 12,819. Then, the statistical jet water flow characteristics, such as the mean velocity, root-mean-square fluctuating velocity, Reynolds stress, and the mean temperature in the upper plenum, were computed and presented. The current study’s results showed that the flow maximum velocity occurred far from the jet inlet. Finally, the temperature profiles were plotted, and it was found that the maximum temperature of the flow occurred close to the plume inlet and after that decreased downstream.
Journal Article
Design and Experimental Validation of a Gas-Flow-Optimised Reactor for the Hydrogen Reduction of Tellurium Oxide
This study presents the development and evaluation of a novel solid–gas reactor designed to enhance the hydrogen reduction kinetics of tellurium oxide (TeO2) under atmospheric pressure. Such gas–solid reactions can be processed in several types of reactors, including but not limited to fixed-bed reactors, moving-bed reactors, and fluidised-bed reactors. A combination of computational fluid dynamics (CFD) and experimental validation was employed to design and optimise a reactor’s geometry and gas-flow distribution. Single-phase CFD simulations were performed using the k–ω SST turbulence model to examine gas-flow behaviour, temperature uniformity, and gas-flow dead zones for two lance designs. The modified lance produced a stable swirling flow that improved gas distribution and eliminated stagnation regions. Experimental trials confirmed the simulation outcome in optimised gas-flow: the redesigned reactor achieved up to 65% conversion after 1 h and 70% after 2 h, a marked improvement over the rotary kiln, which required 5–6 h to reach similar levels. However, excessive gas flow led to cooling effects that reduced conversion efficiency. These results demonstrate the effectiveness of integrated CFD-guided reactor design for accelerating hydrogen-based oxide reduction and advancing sustainable metallurgical processes.
Journal Article
Molecular dynamics study on displacement cascade in F321 austenitic stainless steel
F321 austenitic stainless steel is used in high-temperature, high-pressure, and severe irradiation conditions at high-temperature gas reactors, leading to the formation of irradiation defects such as point defect in the matrix. This study explores the displacement cascade process in F321 austenitic stainless steel based on molecular dynamics (MD) simulations with the aim of investigating the effect of PKA energy, PKA direction and temperature. MD results show that irradiation-induced Frenkel pairs (FPs) number increases with increasing PKA energy. The effect of different PKA directions is not significant when energy is lower than 30 keV, which becomes obviously at 50 keV and 100 keV. In addition, the increasing temperature leads to lower FPs. When it comes to defect cluster, both size and number of clusters increase with increasing PKA energy, which is consistent with the trend with FPs. Vacancy cluster is larger than that of interstitial cluster and the irradiation-induced defect cluster is not significantly dependent on PKA directions. Furthermore, five typical dislocation loops (1/2 < 110>, 1/6 < 112>, 1/3 < 111>, 1/6 < 110 > and 1/3 < 100> ) are observed in samples after displacement cascade, especially high-energy PKA cascades. More interestingly, 1/6 < 112 > dislocation loop is formed first in the displacement cascade process due to its high mobility. These insights reveal systematic irradiation defect formation mechanism during displacement cascade under varied irradiation conditions, offering a new perspective for novel understanding irradiation effect in F321 stainless steel. Based on that, the effect of various factors could be quantified precisely, governing the study of irradiation defects’ generation.
Journal Article