Article

System Design Selection and Parametric Optimization Analysis of 110 kN Nuclear Thermal Rocket Engine

January 2019
Yuanzineng Kexue Jishu/Atomic Energy Science and Technology 53(1):30-37

DOI:10.7538/yzk.2018.youxian.0341

Authors:

Nuclear thermal rocket engine is considered as an ideal power for advanced space exploration, and available system cycles include closed expander cycle, hot bleed cycle and open expander cycle. A comparative study of three different system cycles for a 110 kN nuclear thermal rocket engine based on a ceramic-metallic (CERMET) fuel element was carried out, through the parameter comparison of different system cycles and combinatorial optimization analysis. The optimal system of the engine is considered to be hot bleed cycle. The feasibility of improving engine impulse performance was also discussed. © 2019, Editorial Board of Atomic Energy Science and Technology. All right reserved.

Thermal protection of the nuclear rocket engine nozzle based on regenerative cooling method

Article

Oct 2024
INT J THERM SCI

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Article

Effect of types of ceramic materials in aggregated powder on the adhesive strength of high velocity...

August 2001 · Surface and Coatings Technology

The effects of the types and compositions of the binder phase in WC cermet powders, types of solid materials in solid–liquid two-phase particle, and high velocity oxy-fuel spray conditions on the adhesive strength of high velocity oxy fuel (HVOF) sprayed composite coatings were studied using three aggregated WC cermet powders, Cr3C2–25NiCr, Al2O3–Ni powders, and W–Ni powder. The examination of ... [Show full abstract] the coating microstructure using optical and scanning electron microscopy revealed that all the coatings were deposited through solid–liquid two-phase particles with ceramic particles or W in the powder being in a solid state while the binder in a melted liquid state. It was found that an adhesive strength higher than the strength of the test adhesives of approximately 65 MPa can be reached for all HVOF coatings deposited by WC cermet powders and W–Ni powder. The adhesive strength of HVOF WC cermet coatings was not significantly influenced by the composition of the binder, the powder structure, or the spray parameters. However, for Cr3C2–25NiCr coating the adhesive strength ranged from 35 MPa to over 92 MPa and was significantly influenced by the spray parameters. Finally, Al2O3–Ni coatings had a very limited adhesive strength. The results suggested that the formation of a solid–liquid two-phase particle in the HVOF process is a necessary condition to deposit HVOF coatings of high adhesive strength, while the high density of WC and W particles in the powders is a necessary condition to achieve high adhesive strength for HVOF WC cermet and W–Ni coatings. The adhesive strength of HVOF cermet coatings will be increased with an increase in the density of the solid material component in the two-phase particle.

Article

A Multifunction Cask for At-Reactor Storage of Short-Cooled Spent Fuel, Transport, and Disposal

January 2004

Charles W. Forsberg

The spent nuclear fuel (SNF) system in the United States was designed with the assumptions that SNF would be stored for several years in an at-reactor pool and then transported to reprocessing plants for recovery of fissile materials, that security would not be a major issue, and that the SNF burnups would be low. The system has evolved into a once-through fuel cycle with high-burnup SNF, ... [Show full abstract] long-term storage at the reactor sites, and major requirements for safeguards and security. An alternative system is proposed to better meet these current requirements. The SNF is placed in multifunction casks with the casks used for at-reactor storage, transport, and repository disposal. The cask is the handling package, provides radiation shielding, and protects the SNF against accidents and assault. SNF assemblies are handled only once to minimize accident risks, maximize security and safeguards by minimizing access to SNF, and reduce costs. To maximize physical protection, the cask body is constructed of a cermet (oxide particles embedded in steel, the same class of materials used in tank armor) and contains no cooling channels or other penetrations that allow access to the SNF. To minimize pool storage of SNF, the cask is designed to accept short-cooled SNF. To maximize the capability of the cask to reject decay heat and to limit SNF temperatures from short-cooled SNF, the cask uses (1) natural circulation of inert gas mixtures inside the cask to transfer heat from the SNF to the cask body and (2) an overpack with external natural-circulation, liquid-cooled fins to transfer heat from the cask body to the atmosphere. This approach utilizes the entire cask body area for heat transfer to maximize heat removal rates—without any penetrations through the cask body that would reduce the physical protection capabilities of the cask body. After the SNF has cooled, the cooling overpack is removed. At the repository, the cask is placed in a corrosion-resistant overpack before disposal. This cask design approach can also be used for storage only and dual-purpose (storage and transport) SNF casks.

Article

Full-text available

Effects of coating material and cutting parameters on the surface roughness and cutting forces in dr...

April 2017 · STRUCTURAL ENGINEERING AND MECHANICS

In the present paper, the effects of cutting parameters and coating material on the performances of cutting tools in turning of AISI 52100 steel are discussed experimentally. A comparative study was carried out between uncoated and coated (with TiCN-TiN coating layer) cermet tools. The substrate composition and the geometry of the inserts compared were the same. A mathematical model was developed ... [Show full abstract] based on the Response Surface Methodology (RSM). ANOVA method was used to quantify the effect of cutting parameters on the machining surface quality and the cutting forces. The results show that feed rate has the most effect on surface quality. However, cutting depth has the significant effect on the cutting force components. The effect of coating layers on the surface quality was also studied. A lower surface roughness was observed when using PVD (TiCN-TiN) coated insert. A second order regression model was developed and a good accuracy was obtained with correlation coefficients in the range of 95% to 97%.

Article

MoB–CoCr as alternatives to WC–12Co for stainless steel protective coating and its corrosion behavio...

November 2013 · Surface and Coatings Technology

Erosion of sink rolls by molten zinc is one of the most prominent and persistent problems occurring in hot-dip galvanizing industry. MoB-CoCr as an alternative to WC-12Co for stainless steel protective coating resistance to molten zinc was deposited by high velocity oxygen fuel (HVOF). Microstructure and mechanical characterization of the coatings were carried out by SEM, XRD and micro-hardness ... [Show full abstract] test. Resistance to thermal shock and molten zinc corrosion of the coatings were also conducted. Results showed that MoB-CoCr coating exhibited a better resistance property to thermal shock than that of WC-12Co. At the same time, the corrosion test showed that lifetime of samples with MoB-CoCr coatings in molten zinc appeared to be longer than that of WC coating. The corrosion resistance of MoB-CoCr coating may be ascribed to non-wettability of MoB-CoCr in molten zinc, which can delay the molten zinc penetration into substrates along the micro-cracks of the coating.

Article

Effect of Graphite Contents on the Electrochemical Performance of SOFC Prepared by Tape Casting

June 2011 · RARE METAL MATERIALS AND ENGINEERING

Planar anode-supported intermediate temperature solid oxide fuel half cell has been prepared by aqueous tape casting, using 8% yttria stabilized zirconia(8YSZ) as electrolyte and 8YSZ + NiO + pore former graphite as anode materials, and then the single cell has been prepared by the preparation of cathode by screen printing. The influence of graphite contents on the porosity (including the open ... [Show full abstract] porosity) of anode, microstructure and the electrochemical properties of its single cell has been studied. Associated with the electrochemical performance (power density, electrochemical impedance), the results show that there is an optimum value of graphite content 20% (mass fraction) in anode formula, and the electrochemical properties of the as-prepared single cell is the best. The optimal electrochemical properties at 800 degrees C are shown by the open circuit voltage (OCV) of 1.1 V, the maximum power density of 0.81 W/cm(2) and minimum polarization resistance of 1.25 Omega.cm(2) with the fuel gas of H-2 diluted 3% H2O.

Article

Die Herstellung von Sonderwerkstoffen durch isostatisches Hei�pressen

December 1970 · Materialwissenschaft und Werkstofftechnik

Es wird Über das neuartige Verfahren des isostatischen Heißpressens berichtet. Das Verdichtungsprinzip wird erläutert. Nach einer Literaturschau Über bisherige Arbeiten auf diesem neuartigen Gebiet der Pulvermetallurgie wird die Karlsruher Anlage — die erste dieser Art in der BRD — beschrieben. Die Technik der richtigen Probenvorbereitung für diesen Prozeß wird anhand der Herstellung von ... [Show full abstract] stabförmigen Massiv‐ und Rohrproben erläutert. Als Beispiel wird die Herstellung eines Cermets des Systems Urandioxid‐Molybdän beschrieben. Ein interessanter Nebeneffekt beim isostatischen Heißpressen stellt das Warmverschweißen des Preßlings mit dem Hüllrohr dar. Mögliche Anwendungsgebiete des neuen Verfahrens sind die Herstellung von Brennstäben für schnelle Brutreaktoren, Kathoden und Kollektoren für thermionische Emitter, temperaturwechselbeständige, metallhaltige Keramiken und Sonderkeramiken und Systeme mit Metall‐Keramik‐Diffusions‐Übergängen. Auf dem Gebiet der Werkzeuge aus Schnellstahl bzw. Hartmetall mit hoher Standzeit ist diese Verfahrenstechnik im Vordringen.

Article

Fabrication of porous alumina-based ceramic core using aluminium as pore-forming agent

April 2017 · Huazhong Keji Daxue Xuebao (Ziran Kexue Ban)/Journal of Huazhong University of Science and Technology (Natural Science Edition)

The porous alumina-based ceramic core was built by hot-pressing process. The influences of alumina grain distribution, aluminium content and sintering time on the properties of ceramic cores were studied. The results indicate that alumina grain distribution has significant effects on the properties and compared to other distributions, and ceramic cores made of equal amount of diameters of 80, 58 ... [Show full abstract] and 45 μm possesses better comprehensive performance. Ceramic cores shows increasingly high apparent porosity with the increasing amount of aluminium and ceramic cores with 10% aluminium content have linear shrinkage of -0.85%, bending strength of 30.43 MPa and apparent porosity of 46.99%, there is no obvious influence of sintering time on the properties of cores. After sintered at 1 500℃ for 5 h, ceramic cores still have stable properties, which can meet the demands of ceramic cores in casting area. © 2017, Editorial Board of Journal of Huazhong University of Science and Technology. All right reserved.

Article

NO reduction by propane over iron in wet flue gas

December 2016 · Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and Engineering

The effect of water vapor on NO reduction by propane over iron was experimentally investigated in N2 and simulated flue gas atmosphere respectively. An electrically heated ceramic tubular flowing reactor was used to conduct the tests at 300~1100℃. The iron samples composition and surface microstructure changes were analyzed by XRD and SEM after the ractions. Results showed that water vapor ... [Show full abstract] oxidized iron to iron oxides. In N2 atmosphere, water vapor decreased the NO reduction efficiency at 600~850℃. As the reaction temperature further increased, a porous surface was formed on the oxidized iron and NO could enter the pore to react with fresh iron, therefore, the negative effect of water vapor on NO reduction became weak. In simulated flue gas atmosphere, water vapor promoted NO reduction by propane over iron, especially in fuel-lean conditions. SO2 had very small effect on NO reduction in wet simulated flue gas atmosphere. NO reduction efficiencies by C3H8 over iron were compared to that by CH4 at the same conditions. Results showed that propane reduced NO at a higher efficiency and lower amount of the fuel, e.g., at fuel rich condition, such as SR1=0.9, NO reduction by propane over iron was 14% higher than that by methane at 900℃, while the amount of propane was only 1/3 of that of methane when there was 7.0% water vapor. © 2016, The Editorial Board of Journal of Basic Science and Engineering. All right reserved.

Article

Full-text available

Electrodeposition of Cu into a Highly Porous Ni∕ YSZ Cermet

August 2006 · Journal of The Electrochemical Society

The electrochemical deposition of Cu into 0.12 cm and 60 µm thick, highly porous 65 vol % Ni/yttria-stabilized zirconia (YSZ) cermets was investigated. An electrochemical cell in which the electrolyte solution was allowed to flow through a porous Ni/YSZ substrate was used to eliminate mass-transfer limitations and to determine the conditions for which the potential drop in the electrolyte ... [Show full abstract] solution was minimized and a uniform Cu layer was produced throughout the porous substrate. The conditions determined from these experiments were then used to electrodeposit Cu throughout a thin, porous Ni–YSZ cermet anode layer on a solid oxide fuel cell (SOFC) using a standard nonflow-through setup. This SOFC was found to exhibit stable operation while using methane as the fuel.

Conference Paper

Sodium Compatibility Studies of Low Friction Carbide Coatings for Reactor Application

September 1973 · CORROSION

Design requirements for low friction materials in FFTF have led to an experimental sodium compatibility program, the objective of which is to select and qualify a low friction coating for the fuel assembly duct load pad. Results are given for chromium carbide and titanium carbide-based coatings on stainless steel exposed to 1160 deg F sodium for several thousand hours. A chromium carbide ... [Show full abstract] coating (with a nichrome binder) having an average corrosion rate of approximately 0.25 mpy exhibits optimum sodium compatibility behavior of the materials examined. Both plasma-sprayed chromium carbide and titanium carbide based coatings were found to be unstable when exposed to sodium. (auth)

Article

SAXTON CORE II FUEL PERFORMANCE EVALUATION. PART I. MATERIALS.

January 1971

W.R. Smalley

Article

Redistribution of fuel and fission products in irradiated oxide fuel pins

January 1975