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Auswahl der wissenschaftlichen Literatur zum Thema „Reaction rate molten salt reactors“
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Zeitschriftenartikel zum Thema "Reaction rate molten salt reactors"
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Adinberg, Roman, Michael Epstein und Jacob Karni. „Solar Gasification of Biomass: A Molten Salt Pyrolysis Study“. Journal of Solar Energy Engineering 126, Nr. 3 (19.07.2004): 850–57. http://dx.doi.org/10.1115/1.1753577.
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A novel solar process and reactor for thermochemical conversion of biomass to synthesis gas is described. The concept is based on dispersion of biomass particles in a molten inorganic salt medium and, simultaneously, absorbing, storing and transferring solar energy needed to perform pyrolysis reactions in the high-temperature liquid phase. A lab-scale reactor filled with carbonates of potassium and sodium was set up to study the kinetics of fast pyrolysis and the characteristics of transient heat transfer for cellulose particles (few millimeters size) introduced into the molten salt medium. The operating conditions were reaction temperatures of 1073–1188 K and a particle peak-heating rate of 100 K/sec. The assessments performed for a commercial-scale solar reactor demonstrate that pyrolysis of biomass particles dispersed in a molten salt phase could be a feasible option for the continuous, round-the-clock production of syngas, using solar energy only.
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Xu, Yanke, Hongyan Yan, Zhenwei Jing, Xiwei Qi, Hui Li und Jinglong Liang. „Effect of Fe2O3 on Electro-Deoxidation in Fe2O3-Al2O3-NaCl-KCl System“. Crystals 11, Nr. 9 (26.08.2021): 1026. http://dx.doi.org/10.3390/cryst11091026.
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The reduction of Fe2O3-Al2O3 is one of the important reactions in the resource utilization of iron-containing oxide waste. Fe2O3-Al2O3 was electro-deoxidized in the NaCl-KCl system by molten salt electrolysis to prepare FeO/Al2O3. The effect of the Fe2O3 content on the electro-deoxidation reaction process was studied. The results show that under the conditions of 850 °C, 2.3 V, and electro-deoxidation for 4 h, FeO/Al2O3 could be obtained by controlling the content of Fe2O3. The deoxidation process was divided into three stages: electric double layer charging, Fe2O3 electro-deoxidation to Fe3O4, and Fe3O4 electro-deoxidation to FeO. With the increase in the Fe2O3 content, the deoxidation reaction rate increased, and the low-valence iron oxide particles obtained by electro-deoxidation became larger. The mechanism of the influence of Fe2O3 on the electro-deoxygenation process was determined by analyzing the experimental results. The increase in the Fe2O3 content increased the concentration of activated molecules in the system, while it reduced the resistance of electro-deoxidation. The migration of active particles in the cathode was smoother, which increased the percentage of deoxygenation of activated molecules, thereby shortening the process of the deoxidation reaction.
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Negri, O., und T. Abram. „INFLUENCE OF FUEL FLOW RATE VARIATION ON MOLTEN SALT REACTOR PERFORMANCE“. EPJ Web of Conferences 247 (2021): 01008. http://dx.doi.org/10.1051/epjconf/202124701008.
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Molten Salt Reactors are Gen-IV reactors that use liquid fuel. Fluid fuel allows continuous removal of fission gases as well as batch fuel reprocessing. With these control mechanisms the system can be sustained within the desired operating temperature range and required power output. These methods rely on the presence of a chemical processing plant on-site that adds complexity. This also creates a risk of processing plant unavailability due to faults, emergency downtime or maintenance. The work considers variation of fuel salt flow rate in Molten Salt Reactors as a means of controlling reactor operation without using reprocessing. The analysis is performed using the Molten Salt Fast Reactor as an example. An extended version of the SERPENT Monte-Carlo transport code coupled with OpenFOAM generic platform were used for capturing delayed neutron drift, decay heat, gaseous fission product removal, calculating fuel salt velocity vectors and the fuel temperature distribution. The two models were coupled via a script that accounted for reactivity insertion between time steps and the changes caused in the fission power. Results confirm that, while operating at constant power, the difference between fuel inlet and outlet temperatures increase as the flow rate decreases. Burnup analysis has shown that while the average fuel temperature continues to reduce with time, the difference between inlet and outlet temperatures can be controlled by varying the flow rate while maintaining constant power. Finally, the variation in the fuel flow rate has been shown to extend the reactor operating time with no insertion of additional fissile inventory.
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Chen, Si’an, Hai Feng Hu, Yu Di Zhang, Chang Rui Zhang und Guang De Li. „Low Temperature Preparation of ZrC Coatings on C/C Composite via Molten Salt Reaction“. Key Engineering Materials 531-532 (Dezember 2012): 79–83. http://dx.doi.org/10.4028/www.scientific.net/kem.531-532.79.
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Zirconium carbide (ZrC) coatings were prepared on C/C composite via molten salt reaction process at relatively low temperatures of 800-1000°C. During the reaction process, potassium fluorozirconate (K2ZrF6) played a role transporting zirconium from the molten salt to the C/C composite surface. Elevating reaction temperature increased the growth rate of coatings, simultaneously leaded to rougher coatings. The coatings growth rate increased with reaction time at first and then decreased gradually. The ZrC coatings prepared at 900°C for 5h was ~2m thickness. At the early stage, the low solubility of zirconium in the molten salt leaded to the low coatings growth rate. Secondly, the growth rate of the ZrC coatings was controlled by the chemical reaction between C/C composites and zirconium once zirconium was saturated in the molten salts. Thirdly, the control step of coatings formation turned into the diffusion of carbon through the formed ZrC coatings and which leaded to a gradual decrease of growth rate.
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Yasuda, K., K. Kondo, S. Kobayashi, T. Nohira und R. Hagiwara. „Selective Formation of Rare Earth-Nickel Alloys via Electrochemical Reactions in NaCl-KCl Molten Salt“. ECS Transactions 64, Nr. 4 (15.08.2014): 601–7. http://dx.doi.org/10.1149/06404.0601ecst.
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Yasuda, Kouji, Katsuya Kondo, Seitaro Kobayashi, Toshiyuki Nohira und Rika Hagiwara. „Selective Formation of Rare-Earth–Nickel Alloys via Electrochemical Reactions in NaCl–KCl Molten Salt“. Journal of The Electrochemical Society 163, Nr. 5 (2016): D140—D145. http://dx.doi.org/10.1149/2.0501605jes.
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van Erk, W. „Transport processes in metal halide gas discharge lamps“. Pure and Applied Chemistry 72, Nr. 11 (01.01.2000): 2159–66. http://dx.doi.org/10.1351/pac200072112159.
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An overview is given of transport reactions and corrosion phenomena in metal halide gas discharge lamps filled with a mixture of alkali halides with scandium or rare-earth iodides. The phenomena that are discussed are: (a) pressures of light-emitting species above the molten salt mixture, (b) interaction of the metal halides with the vessel wall, quartz glass as well as polycrystalline alumina, (c) transport processes along the vessel wall giving rise to wall corrosion, and (d) transport to and from the electrodes (i.e., electrode corrosion and wall blackening).
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Han, Yan Fang, Ti Chang Sun, Jie Li, Li Na Wang, Tian Yan Xue und Tao Qi. „Removing of Si in the NaOH Molten Salt Reaction of Titanium Slag to Produce TiO2“. Advanced Materials Research 418-420 (Dezember 2011): 387–92. http://dx.doi.org/10.4028/www.scientific.net/amr.418-420.387.
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NaOH solution was utilized in the molten salt reaction of titanium slag for investigating desiliconization effects. The thermodynamic behaviors of Si in the reaction system was examined to explore the impacts of molten salt reaction conditions on the conversion rates of the foreign substance Si and the target element Ti. On this basis, the influences of NaOH concentration, liquid-solid ratio, cleaning temperature and cleaning time on Si removing rate were discussed. The experimental results showed that, Si reacted with NaOH to produce sodium silicate was feasible in terms of thermodynamics within the temperature interval 400-1000K. 3Na2O•2SiO2, 2Na2O•SiO2 could stably exist under high reaction temperature. As the reaction time extended and temperature rose, the conversion rate of Si was increasing. In the process of Si removing by NaOH cleaning of molten salt reaction products, as NaOH concentration, liquid-solid ratio, cleaning temperature and cleaning time increased, Si removing rate became larger. The optimum alkali cleaning conditions were: NaOH concentration 150g/l, liquid-solid ratio 3:1, cleaning temperature 50°C and cleaning time 60min, then the desiliconization rate reached 61.16%.
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Ouyang, Zhen, Longgang Ye, Chaobo Tang und Yuntao Xin. „Reaction Behaviors of Associated Minerals in Molten Salt Smelting of Stibnite and Kilogram-Class Trials“. Metals 10, Nr. 1 (25.12.2019): 43. http://dx.doi.org/10.3390/met10010043.
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The molten salt metallurgy of Sb, which involves the smelting of stibnite in a binary NaCl-Na2CO3 salt with sulfur-fixing and the addition of a reductant, has been proposed as a clean method for Sb extraction. However, the reacting behaviors of the minerals associated with stibnite (Sb2S3) during the smelting are still unclear, and industrial tests have not been conducted. This study investigated the behaviors of PbS, FeS2, SiO2, and CaCO3, which are the main minerals associated with stibnite, during reducing smelting by using the NaCl-Na2CO3 molten salt. The results showed that PbS could react with Na2CO3 to generate metallic Pb at 950 °C. FeS2 and SiO2 formed stable NaFeS2 and Na2SiO3 with the molten salt at a high temperature, respectively. CaCO3 formed an unstable intermediate product of Na2Ca(CO3)2 at 675 °C and decomposed with increasing temperature. Kilogram-class trials were also performed using 50 kg of concentrate and more than 300 kg of mixture material, and the results showed that the direct recovery rate of Sb and Au reached maximum values of 93.22% and 92.06% at temperature 920 °C in eutectic Na2CO3-NaCl molten salt, respectively, while the total sulfur-fixing ratio reached 99.49%. Thus, the associated minerals consumed the molten salt, and the feasibility of molten salt smelting was verified by this kilogram-class pilot experiment.
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Lu, Ningning, und Donglai Xie. „Novel Membrane Reactor Concepts for Hydrogen Production from Hydrocarbons: A Review“. International Journal of Chemical Reactor Engineering 14, Nr. 1 (01.02.2016): 1–31. http://dx.doi.org/10.1515/ijcre-2015-0050.
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AbstractMembrane reactors are attracting increasing attention for ultrapure hydrogen production from fossil fuel, integrating catalytic reaction and separation processes into one single unit thus can realize the removal of hydrogen or introduction of reactant in situ, which removes the thermodynamic bottleneck and improves hydrogen yield and selectivity. In this review, the state-of-the-art concepts for hydrogen production through membrane reactors are introduced, mainly including fixed bed membrane reactors, fluidized bed membrane reactors, and micro-channel membrane reactors, referring higher hydrocarbons as feedstock, such as ethanol, propane, or heptane; novel heating methods, like solar energy realized through molten salt; new modular designs, including panel and tubular configurations; ultra-compact micro-channel designs; carbon dioxide capture with chemical looping; multifuel processors for liquid and/or solid hydrocarbons; etc. Recent developments and commercialization hurdles for each type of membrane reactor are summarized. Modeling the reactor is fundamental to explore complex hydrodynamics in reactor systems, meaningful to investigate the effects of some important operating factors on reactor performances. Researches for reactor modeling are also discussed. Reaction kinetics for hydrocarbons reforming and reactor hydrodynamics are summarized respectively. Cold model is introduced to investigate physical phenomena in reactors.
Dissertationen zum Thema "Reaction rate molten salt reactors"
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Burian, Jiří. „Experimentální a výpočetní výzkum vlastností solí pro jaderné reaktory typu MSR z pohledu jaderných dat“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442467.
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Nowadays there is research into molten salt reactors. The use of chlorine-based salts, which would be more available than known fluoride salts, is envisaged. The subject of research is not only the chemical and physical properties of chloride salts, but also their behavior in the neutron field and the influence of neutron balance inside the reactor. Many properties can also be determined using calculations that draw information from scientific nuclear libraries (endf). The purpose of this work is to compare important nuclear libraries with each other, and also to compare the reaction rates calculated from the library data with the reaction rates obtained by self-measurement. The preview will include a description of the necessary activities associated with the preparation of measurements, instructions for compiling the computer program NJOY and the process of the measurement itself. At the end of the work will be summarized the results and statements of which nuclear library is the closest in its values to the results of experiments.
Buchteile zum Thema "Reaction rate molten salt reactors"
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Tao, Shaohu, Jianping Peng, Yuezhong Di, Kejia Liu, Kun Zhao und Naixiang Feng. „Electrochemical Study of Potassium Fluoride in a Cryolite-Aluminum Oxide Molten Salt“. In Encyclopedia of Aluminum and Its Alloys. Boca Raton: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-140000409.
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Selective and efficient electrochemical methods to characterize aluminum are necessary. Current methods are based on potentiodynamic polarization, recurrent potential double pulses, chronopotentiometry, open-circuit chronopotentiometry, and potentiostatic electrolysis, but have not been used to characterize the deposition of aluminum in Na3AlF6-Al2O3-KF molten salts. The control processes of the formation of aluminum-tungsten inter-metallic compounds, and the deposition of aluminum have been investigated by using steady-state potentiodynamic cathodic polarization curves. The dissolution loss rate of aluminum was determined with an increase in KF concentration by the analysis of recurrent potential double pulses. Using chronopotentiometry, it was confirmed that the deposition potential of aluminum shifted more negative as the KF concentration increased, and a higher KF concentrations induced a higher cathodic overpotential. From open-circuit potential measurements and scanning electron micrographs, it was concluded that aluminum(III) ions react with tungsten substrates to form an aluminum-tungsten compound, and the reaction mechanism of aluminum was determined. These electrochemical methods applied with aluminum electrolysis were accurate, efficient, and reliable.
Konferenzberichte zum Thema "Reaction rate molten salt reactors"
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Hathaway, Brandon J., Jane H. Davidson und David B. Kittelson. „Solar Gasification of Biomass: Kinetics of Pyrolysis and Steam Gasification in Molten Salt“. In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-39829.
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The use of concentrated solar energy for pyrolysis and gasification of biomass is an efficient means for production of hydrogen rich synthesis gas. Utilizing molten alkali-carbonate salts as a reaction and heat transfer media offers enhanced stability and higher reaction rates to these solar processes. To establish the reaction kinetics, experiments were carried out in an electrically heated molten salt reactor. Cellulose or activated charcoal were pyrolyzed or gasified with steam from 1124 K to 1235 K with and without salt. Arrhenius rate expressions are derived from the data supported by a numerical model of heat and mass transfer. The average rate of the reactions in molten salt, as measured by their reactivity index, is increased by 70% for pyrolysis and by an order of magnitude for steam gasification.
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Zhang, Zhihong, Xiaobin Xia, Jianhua Wang und Changyuan Li. „Primary Shielding Design for an Optimized Molten Salt Reactor“. In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-15821.
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Molten salt reactor (MSR) system, a candidate of the Generation IV reactors, has inherent safety, on-line refueling and good neutron economy as typical advantages. An optimized MSR is developed by changing the size of fuel channel and the graphite-to-molten salt volume radio, based on the Molten-Salt Reactor Experiment (MSRE), which was originally developed at the Oak Ridge National Laboratory (ORNL). In this paper, shielding calculations for the optimized MSR are presented. The goal of this study is to determine the necessary shielding to decrease the neutron and gamma dose rate to the acceptable level according to national regulations. The operating temperature of the optimized MSR is designed in the range of 500 °C–700 °C, heat removal is also considered in the shielding design. The shielding calculations are carried out by using Monte Carlo method. The shielding system of the optimized MSR consists of 7 zones: the core, the core can, the reactor vessel, the thermal shield, the reactor cell containment, the shield tank and the concrete wall. The combinations of shielding materials in the thermal shield were evaluated. The thermal shield filled with carbon steel balls and circulating water gets an excellent shielding performance and heat removing effects. The neutron spectra and dose distributions, as well as the energy deposition over different shields have been analyzed. The total neutron dose rate outside the thermal shield is attenuated by a factor of about 104, and the gamma dose rate by a factor of about 103. These results show that the shielding design could low dose rate to an acceptable level outside the shielding and far below dose limit required.
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Zhou, Jianjun, Suizheng Qiu, Zhangpeng Guo und Guanghui Su. „The Optimization Design of Lower Plenum and Distribution Plates in MSR“. In 2013 21st International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icone21-16436.
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Molten salt reactor was one of six Generation IV reactor types, which uses the liquid molten salt as the coolant and fuel solvent. In transmutation of actinides and long-lived fission products have marked advantages. As a liquid reactor the physical property and thermo-characteristic is different to solid fuel and water coolant reactors, which was influenced by many factors. MOSART was one of the advanced molten salt reactors concept design, which can burners TRU from LWR spent fuel. The reactor core does not contain graphite structure elements, so the flow pattern was potentially complex and may significantly affect the fuel temperature distributions. The optimizations of the salt flow may be needed, the present work designed three core models and three kinds of distribution plates to investigate the influence of lower plenum and distribution plates to thermohydraulics characteristics of the reactor core with CFD method use software FLUENT. Velocity field and maximum temperature of the core was simulated in each model at different mass flow rate.
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Iwaki, Hiroyuki, Gong Jin, Tomohiko Furuhata und Norio Arai. „Reaction Characteristics of Wastepaper Gasification With CO2 Catalyzed by Molten Carbonate Salts“. In 2002 International Joint Power Generation Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/ijpgc2002-26076.
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In this paper, wastepaper gasification with steam and carbon dioxide was tested in the presence of molten carbonate salt catalysts. Reactions with steam or carbon dioxide were first compared. Hydrogen was mainly produced by gasification with steam, but no carbon monoxide was generated. For the case where carbon dioxide was used as a reactant instead of steam, generation of carbon monoxide greatly increased via the Boudouard reaction. Different ratios of mixtures of lithium, sodium and potassium carbonates were examined. Lithium was found to play a critical role in the various catalyst combinations. The reaction rate with respect to carbon conversion was approximately first order for low carbon conversions. The rate constants were investigated at different temperatures (923–1023K) and the activation energies were determined. In addition, the flexibility of this technique was examined with three different types of wastepaper. These results suggest the applicability of this process for the effective use of wastepaper and recovery of carbon dioxide.
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Ruan, Jian, Yang Zou, Minghai Li und Hongjie Xu. „Control Scheme Research of 10MW Fluoride Salt Cooled High Temperature Experiment Reactor“. In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-66228.
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Fluoride salt cooled High temperature Reactor (FHR) is a kind of Gen-IV reactor which possesses many attractive features, such as high temperature, low pressure etc. Thermal-hydraulic features of molten salt are different from coolants of traditional reactors, which dominate operation transient behavior of FHR. However, as a new type reactor with sphere fuel element and fluoride salt coolant, FHR has inadequate operating experience and data used for reactor control and the design of power regulating system. Therefore, research of power regulation strategy is very important for FHR in automatic control operation and commercial application. A code programmed in Fortran platform is used for investigating the system transient behavior, control logic and strategy. Based on the transient analysis code OCFHR for FHR, power control logic strategy is studied on a model of 10 MW Fluoride salt cooled High Temperature Experiment Reactor. OCFHR is a specialized code in FHR transient analysis, which contains point reactor model, simplified core thermal-hydraulic model, molten salt-salt exchanger and molten salt-air exchanger with a tube-shell type, control rod system and power regulation and control model. The control module of OCFHR uses the incremental PID controller to regulate control parameters and adopts the compound mode of control rod adjustment, load adjustment and molten salt flow adjustment, so that it can adjust the control rod position, primary and secondary molten salt flow rate and air flow rate of load at different operating power levels. Two kinds of steady operation strategies are studied in this paper, which are a) constant outlet coolant temperature and b) constant average coolant temperature. The power level is regulated by control rod while the working temperatures are adjusted by shifting the load with weight coefficients of power and temperature deviations. The results show that the incremental PID controller with optimized parameters can achieve the control requirement. Both of temperature control strategies gain great performances under 10%FPand 50%FP power regulation. The target power is reached quickly and accurately by using the incremental PID controller while the temperature control is very time-consuming. Compared with b), strategy a) has less temperature overshoot but larger power overshoot and longer adjusting time. The step wise power regulation for FHER is doable when a wide power adjustment range is needed and the simulation 10%FP treated as a step works well. Besides, the preliminary study of varying secondary coolant flow rate also indicates that the secondary loop plays an important part in restraining the deviation of secondary coolant temperatures during the process of balancing the power and load, so it is better to adjust the secondary coolant flow in terms of the power regulation range.
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Zhang, Sheng, Shanbin Shi, Xiao Wu, Xiaodong Sun und Richard Christensen. „Double-Wall Natural Draft Heat Exchanger Design for Tritium Control in FHRs“. In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-67844.
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Tritium control is potentially a critical issue for Fluoride salt-cooled High-temperature Reactors (FHRs) and Molten Salt Reactors (MSRs). Tritium production rate in these reactors can be significantly higher compared to that in Light Water Reactors (LWRs). Tritium is highly permeable at high temperatures through reactor structures, especially. Therefore, heat exchangers with large heat transfer areas in FHRs and MSRs provide practical paths for the tritium generated in the primary salt migrating into the surroundings, such as Natural Draft Heat Exchangers (NDHXs) in the direct reactor auxiliary cooling system (DRACS), which are proposed as a passive decay heat removal system for these reactors. A double-wall heat exchanger design was proposed in the literature to significantly minimize the tritium release rate to the environment in FHRs. This unique shell and tube heat exchanger design adopts a three-fluid design concept and each of the heat exchanger tube consists of an inner tube and an outer tube. Each of these tube units forms three flow passages, i.e., the inner channel, annular channel, and outer channel. While this type of heat exchangers was proposed, few such heat exchangers have been designed in the literature, taking into account both heat and tritium mass transfer performance. In this study, a one-dimensional heat and mass transfer model was developed to assist the design of a double-wall NDHX for FHRs. In this model, the molten salt and air flow through the inner and outer channels, respectively. A selected sweep gas acting as a tritium removal medium flows in the annular channel and takes tritium away to minimize tritium leakage to the air flowing in the outer channel. The heat transfer model was benchmarked against a Computational Fluid Dynamics (CFD) code, i.e., ANSYS Fluent. Good agreement was obtained between the model simulation and Fluent analysis. In addition, the heat and mass transfer models combined with non-dominated sorting in generic algorithms (NSGA) were applied to investigate a potential NDHX design in Advanced High-Temperature Reactor (AHTR), a pre-conceptual FHR design developed by the Oak Ridge National Laboratory. A double-wall NDHX design using inner and outer fluted tubes was therefore optimized and compared with a single-wall design in terms of performance and economics.
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Tyagi, Himanshu, Patrick E. Phelan und Ravi S. Prasher. „Thermochemical Conversion of Biomass Using Solar Energy: Use of Nanoparticle-Laden Molten Salt as the Working Fluid“. In ASME 2009 3rd International Conference on Energy Sustainability collocated with the Heat Transfer and InterPACK09 Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/es2009-90039.
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Solar energy can potentially be used to convert biomass into more readily usable fuel. The use of solar energy in such a process improves the overall conversion efficiency of the system significantly by eliminating combustion of a portion of biomass needed to heat the rest of it to a temperature where pyrolysis occurs. The present study models the thermochemical conversion process during pyrolysis of biomass matter into product gases. Concentrated solar radiation is used as the source of heating of the biomass. The biomass is indirectly heated by a mixture of molten salts (Na2CO3 and K2CO3) and nanoparticles (copper), which acts as the absorbing medium and in turn heats the biomass matter (cellulose). A two-stage heat transfer and chemical reaction analysis is carried out in order to simulate the simplified operating conditions of a solar-powered gasifier. The temperature of the molten salt at the exit of the reactor is held fixed at 1000 K (727°C). The calculations are carried out at different values of solar concentration factor ranging from 10 to 60. The results show that the temperature of the molten salt mixture at the exit of the solar collector increases with an increase in the solar concentration factor. Moreover the temperature inside the biomass reactor is a function of the concentration factor as well and largely the determining factor of the rate of biomass conversion into product gases. At the highest concentration factor (Cf = 60), the model predicts that the reactor is able to convert 1.1 tons of biomass into product gases each hour using 900 kW of solar radiation at an overall efficiency of 8%. The main finding of this study is that under similar operating conditions a solar collector using a direct absorption fluid (mixture of nanoparticles and molten salt) would require significantly less concentration factor (an order of magnitude reduction) than a conventional solar collector. A conventional solar collector is defined as one where the solar radiation heats up a solid surface (such as tube walls) which in turn heats up the working fluid (molten salt). Such a reduction in concentration factor would translate into lower concentrator area, and consequently lower initial capital cost.
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Sabharwall, Piyush, Hans Schmutz, Carl Stoots und George Griffith. „Tritium Production and Permeation in High-Temperature Reactor Systems“. In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17036.
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Tritium (H13) is a radioactive isotope of hydrogen formed by ternary fission events (rare emissions of three nuclides rather than two during a fission) and neutron absorption (and subsequent decay) of predecessor radionuclides, particularly 6Li and 7Li. Also in fusion, the concept of breeding tritium during the fusion reaction is of significance for the future needs of a large-scale fusion power plant. Tritium is of special interest among the fission products created in next-generation nuclear reactors such as gas cooled reactors and molten salt reactors, because of the large quantities produced when compared with conventional light-water reactors (LWR) and the higher temperatures of operation for these systems enhances permeation. To prevent the tritium contamination of proposed reactor buildings and surrounding sites, this paper examines the root causes and potential solutions for mitigation of permeation of this radionuclide, including materials selection and inert gas sparging. A model is presented that can be used to predict permeation rates of hydrogen through metallic alloys at temperatures from 450–750°C. Results of the diffusion model are presented along with mitigation strategies for tritium permeation.
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Chen, Chen, Keith Lovegrove, H. Pirouz Kavehpour und Adrienne S. Lavine. „Design of an Ammonia Synthesis System for Producing Supercritical Steam in the Context of Thermochemical Energy Storage“. In ASME 2015 Power Conference collocated with the ASME 2015 9th International Conference on Energy Sustainability, the ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2015 Nuclear Forum. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/power2015-49190.
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Concentrating solar power plants typically incorporate thermal energy storage, e.g. molten salt tanks. The broad category of thermochemical energy storage, in which energy is stored in chemical bonds, has the advantage of higher energy density as compared to sensible energy storage. In the ammonia-based thermal energy storage system, ammonia is dissociated endothermically as it absorbs solar energy during the daytime. The stored energy can be released on demand (for electricity generation) when the supercritical hydrogen and nitrogen react exothermically to synthesize ammonia. Using ammonia as a thermochemical storage system was validated at Australian National University (ANU), but ammonia synthesis has not yet been shown to reach temperatures consistent with the highest performance modern power blocks such as a supercritical steam Rankine cycle requiring steam to be heated to ∼650°C. This paper explores the preliminary design of an ammonia synthesis system that is intended to heat steam from 350°C to 650°C under pressure of 26 MPa. A two-dimensional pseudo-homogeneous model for packed bed reactors previously used at ANU is adopted to simulate the ammonia synthesis reactor. The reaction kinetics are modeled using the Temkin-Pyzhev reaction rate equation. The model is extended by accounting for convection in the steam to predict the behavior of the proposed synthesis reactor. A parametric investigation is performed and the results show that heat transfer plays the predominant role in improving reactor performance.
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Bei, Hua, Jinkun Zhao, Qichang Chen und Shengyi Si. „The Verification of SONG Library“. In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-66946.
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We have developed the 293-group cross-section library SONGLIB with complete reaction pathes, broad-spectrum solving ability and wide range isotopes, which is adopted in the lattice code SONG, the next generation reactor lattice calculation and analysis code. SONGLIB provides the multi-group data for the transport calculation, resonance calculation and burnup calculation of SONG. So the precision and reliability of data is very important. However, the size of the data is very large and there are still a lot of personal factors in determination of the processing parameters and methods. In order to evaluate the library, it’s necessary to carry out the test work comprehensively. Amount of test work is then undertaken based on three kinds of reactors such as pressurized water reactor with UO2 fuel, sodium cooled fast reactor and new-type molten salt reactor with none-beryllium core. In order to test the adaptivity of the library, 39 cases are designed totally, changing the fuel composition, the absorber compositon, the burnup depth and the working temperature. Only the results of a few cases are given in details to shorten the length of this article. For comparison, the Monte Carlo code MCNP is chosen and the library source of evaluated nuclear data is ensured to be the same. The model that has been calculated is simple, the cell with “fuel-cladding-modulator” the three-layer structure and total reflection boundary for the aim of minimizing the differences between the codes. From the macroscopic angle, the results of infinite multiplication factor fit well with each other in total. From the microscopic angle, the absorption rate for actinides, fission products and absorbers, the fission rate for fissile isotopes and scattering rate for moderators are compared with that of MCNP whose output is normalized to the actual cell power. The difference between the reaction rates for most isotopes can be neglected. But there still exist some obvious differences for some isotopes whose resonance effect should have been considered, such as Fe56, ZrNat and W, which might affect the macoscopic results to some extent. As a conclusion, the data of SONGLIB can be expected with high precision and reliability. And SONGLIB is adapted in solving various problems for reactors with different spectrum, depth of burnup, operation condition or fuel cycling. Nevertheless, there still exist some factors that may affect the final results during the process and use of the library, which should be paid attention to while taking a further step in optimizing and updating the library.
Berichte der Organisationen zum Thema "Reaction rate molten salt reactors"
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Feng, Bo, und Yan Cao. Assessment of Tools for Molten Salt Reactor Dose Rate Calculations. Office of Scientific and Technical Information (OSTI), August 2021. http://dx.doi.org/10.2172/1820617.
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