• Title/Summary/Keyword: Fuel Properties

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A MICROSTRUCTURAL MODEL OF THE THERMAL CONDUCTIVITY OF DISPERSION TYPE FUELS WITH A FUEL MATRIX INTERACTION LAYER

  • Williams, A.F.;Leitch, B.W.;Wang, N.
    • Nuclear Engineering and Technology
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    • v.45 no.7
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    • pp.839-846
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    • 2013
  • This paper describes a finite element model of the microstructure of dispersion type nuclear fuels, which can be used to determine the effective thermal conductivity of the fuels during irradiation. The model simulates a representative region of the fuel as a prism shaped unit cell made of brick elements. The elements within the unit cell are assigned material properties of either the fuel or the matrix depending on position, in such a way as to represent randomly distributed fuel particles with a size distribution similar to that of the as manufactured fuel. By applying an appropriate heat flux across the unit cell it is possible to determine the effective thermal conductivity of the unit cell as a function of the volume fraction of the fuel particles. The presence of a fuel/matrix interaction layer is simulated by the addition of a third set of material properties that are assigned to the finite elements that surround each fuel particle. In this way the effective thermal conductivity of the material may also be determined as a function of the volume fraction of the interaction layer. Work is on going to add fission gas bubbles in the fuel as a fourth phase to the model.

Preliminary Properties and Combustion Behavior of Solidified Ethanol Fuel (고형 에탄올 연료의 기본 물성치 및 연소특성)

  • Kim, Hyemin;Jo, Min Kyung;Yang, Sung Ho
    • Journal of Aerospace System Engineering
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    • v.13 no.3
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    • pp.9-14
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    • 2019
  • Liquid and solid fuels currently in use have various pros and cons. As a result, researches are dedicated to produce a new form of fuel that utilizes the advantages and overcomes weakness of conventional fuels. In the present study, a new method for making solidified ethanol fuel is introduced, and its preliminary properties and combustion characteristic are observed. The solidified ethanol fuel was made through the production of agarose hydrogel, and its subsequent soaking into pure ethanol. The properties of the solidified ethanol fuel were quantitatively and qualitatively observed, and its validity and applicability discussed.

Effect of UO2+x Powders Produced at Different Oxidation Temperatures on the Properties of Pellet

  • Yoo, Ho-Sik;Lee, Seung-Jae;Kim, Jae-Ik;Song, Kun-Woo
    • Journal of the Korean Ceramic Society
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    • v.40 no.5
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    • pp.410-414
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    • 2003
  • Characteristics of $UO_{2+x}$ powders oxidized at different temperatures were examined. Pellets were fabricated by adding these oxidation powders and their properties were also investigated. Particle size of the $UO_{2+x}$ powders decreased with increasing oxidation temperature while surface area increased. Only the powders oxidized at 35$0^{\circ}C$ enhanced the strength of green pellet. However, 35$0^{\circ}C$ oxidized powders added pellet had many surface defects. The difference of shrinkage rate between the oxidized and UO$_2$ powders was thought to be the cause of them.

A Impact Study on Combustion Characteristics of the Engine by Changing the Gasoline Properties (휘발유 물성변화가 엔진의 연소특성에 미치는 영향 연구)

  • Noh, Kyeong-ha;Im, Sang-bin;Lee, Min-ho;Kim, Ki-ho;Ha, Jong-han
    • Journal of Energy Engineering
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    • v.24 no.4
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    • pp.166-174
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    • 2015
  • This study examined combustion characteristics by selecting the fuel which have a different physical properties compared to gasoline in order to examine the effects of vehicle performance and environment depending on the physical properties. The experiment examined the combustion characteristic in the optimum ignition timing according to the physical properties change and the lean burn by performing control about ignition timing and air-fuel ratio for each fuel, and it was also evaluated the exhaust gas according to the experiment. We used a single-cylinder engine for the experiment, and tested for gasoline properties change by selecting a fake fuel that beyond the fuel quality standards in 석대법. As a result, in the case of the selected fuel showed a difference in Octane and distillation characteristics, vapor pressure and it was also found to unstable combustion, and leads to a large amount of harmful exhaust gas.

Crush Strength Analysis of a Spacer Grid for PWR Nuclear Fuel Considering Mechanical Properties in Weld Zone (용접부 기계적 물성치를 고려한 경수로 핵연료 지지격자의 충격해석)

  • Song, Kee-Nam;Lee, Sang-Hoon
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.8 no.2
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    • pp.7-13
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    • 2012
  • A spacer grid which is one of the most important structural components in a pressurized water reactor fuel is an interconnected array of slotted grid straps, welded at the intersections to form an egg-crate structure. The spacer grid is required to not only protect fuel rods stably but also have sufficient lateral crush strength for the sake of enabling shut-down of the nuclear reactor during abnormal operating environments. Then, the lateral crush strength of the spacer grid is closely related with welding quality of the spacer grid. Previous research on the crush strength analysis of the spacer grid had been performed using only parent material properties. In this study, to investigate the effect on the crush strength of the spacer grid when used mechanical properties in weld zone instead of parent material properties, crush strength analysis considering mechanical properties in weld zone obtained from the instrumented indentation technique was performed and compared the results with the previous research.

Microstructural and Mechanical Properties of Ta-bearing 9%Cr Ferritic/Martensitic Steels (탄탈륨 함유 9%Cr 페라이트/마르텐사이트 강의 미세조직 및 기계적 특성)

  • Baek, Jong-Hyuk;Han, Chang-Hee;Kim, Sung-Ho;Lee, Chan-Bock;Hahn, Dohee
    • Korean Journal of Metals and Materials
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    • v.47 no.4
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    • pp.209-216
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    • 2009
  • It was evaluated that the microstructural and mechanical properties of Ta-bearing 9Cr-0.5Mo-2W ferritic/martensitic experimental steels. All the experimental steels showed the tempered martensitic microstructures, and $M_{23}C_6$ carbides, whose sizes were ranged from 200 to 300 nm, were easily observed at both boundaries of the prior austenite grain and the martensite lath. In addition, a relatively large Nb-rich MX carbonitrides were intermittently detected at the prior austenite grain boundaries, whereas a lot of Vrich MX carbonitrides, whose mean diameter was less than 50 nm, were observed randomly at both boundaries. Ta was mainly incorporated into the V-rich MX carbonitrides rather than the Nb-rich ones and their content was spanned from 5 to 20 at.%. Ta contents within the MX precipitates also increased as the content of Ta increased. Because the Ta addition into the steels would be attributed to the precipitation strengthening, solid solution strengthening and lath width reduction, it was shown that the mechanical properties, including hardness, tensile strength and creep rate of the 9%Cr-0.5Mo-2W steels were improved by the increase of Ta content. Especially, 9Cr-0.5Mo-2W-0.3V-0.05Nb-0.14Ta steel was revealed to be relatively excellent in the application for the SFR fuel cladding.

Correlation Between Surface Properties of Fuel and Performance of Direct Carbon Fuel Cell by Acid Treatment (석탄 산처리에 따른 연료의 표면 물성 변화와 직접탄소 이용 연료전지 성능 간의 상관관계 분석분석)

  • Kim, Dong Heon;Eom, Seong Yong;Choi, Gyung Min;Kim, Duck Jool
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.11
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    • pp.697-704
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    • 2016
  • Coal modified by acid treatment was investigated to analyze the correlation between the cell performance and electrochemical parameters in a direct carbon fuel cell (DCFC). The fuels were subjected to thermogravimetry analysis, gas adsorption test, and X-ray photoelectron spectroscopy to investigate the fuel properties and surface characteristics. After the treatment of raw coal, the thermal reactivity of the treated fuels increased, and the specific surface area decreased, though the mean pore diameters of three fuels were similar. The coal treated by $HNO_3$ showed the highest ratio of oxygen to carbon, and also an increase in the surface oxygen groups on the fuel surface. Through comparison between the fuel surface properties and electrochemical performance, it was confirmed that the surface oxygen groups have an influence on the improvement in the DCFC performance.

USE OF A CENTRIFUGAL ATOMIZATION PROCESS IN THE DEVELOPMENT OF RESEARCH REACTOR FUEL

  • Kim, Chang-Kyu;Park, Jong-Man;Ryu, Ho-Jin
    • Nuclear Engineering and Technology
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    • v.39 no.5
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    • pp.617-626
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    • 2007
  • A centrifugal atomization process for uranium fuel was developed in order to fabricate high uranium density dispersion fuel for advanced research reactors. Spherical powders of $U_3Si$ and U-Mo were successfully fabricated and dispersed in aluminum matrices. Thermal and mechanical properties of dispersion fuel meat were characterized. Irradiation tests at the research reactor HANARO confirm the excellent performance of high uranium density dispersion fuel.