• Nuclear Engineering and Technology
• /
• 제43권1호
• /
• pp.19-24
• /
• 2011

These experimental studies are carried out to build a database for analyzing fuel performance in nuclear power plants. In particular, this study focuses on the mechanical and irradiation properties of three kinds of zirconium alloy (Alloy A, Alloy B and Alloy C) irradiated in the HANARO (High-flux Advanced Neutron Application Reactor), one of the leading multipurpose research reactors in the world. Yield strength and ultimate tensile strength were measured to determine the mechanical properties before and after irradiation, while irradiation growth was measured for the irradiation properties. The samples for irradiation testing are classified by texture. For the irradiation condition, all samples were wrapped into the capsule (07M-13N) and irradiated in the HANARO for about 100 days (E > 1.0 MeV, $1.1{\times}10^{21}\;n/cm^2$). These tests and results indicate that the mechanical properties of zirconium alloys are similar whether unirradiated or irradiated. Alloy B has shown the highest yield strength and tensile strength properties compared to other alloys in irradiated condition. Even though each of the zirconium alloys has a different alloying content, this content does not seem to affect the mechanical properties under an unirradiated condition and low fluence. And all the alloys have shown the tendency to increase in yield strength and ultimate tensile strength. Transverse specimens of each of the zirconium alloys have a slightly lower irradiation growth tendency than longitudinal specimens. However, for clear analysis of texture effects, further testing under higher irradiation conditions is needed.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• 제33권8호
• /
• pp.589-595
• /
• 2009

The instability wave formed near nozzle region grows to vortex with large scale in downstream region of spray. It plays an important role in the fuel-air mixing, combustion process and engine exhaust emissions in direct injection diesel engine. The objective of this study is to analyze effect of variant parameters (injection pressure, ambient gas density, etc.) and fuel properties on spray instability near nozzle region. Spray structure near nozzle region was investigated using a magnification photograph. A pulsed Nd-YAG laser was used as a light source, and image was taken by CCD camera. The following conclusions are drawn from this experimental analysis. In low ambient density, the effect of fuel properties on spray instability near nozzle region is dominant. In high ambient density, the effect of ambient gas on spray instability near nozzle region is dominant. High jet velocity has strong influence on spray instability.

• Transactions of the Korean Society of Automotive Engineers
• /
• 제3권6호
• /
• pp.162-175
• /
• 1995

Exhaust emissions in diesel engine are affected by fuel properties, but the reason for this is not clear. Especially, the recent strong interest in using low-grade fuel such as used vegetable oil as alternative diesel fuel demands extensive investigation in order to clarify the exhaust emissions. The purpose of this study is to evaluate the feasibility of a used vegetable oil as an alternative fuel in a diesel engine in terms of exhaust emissions. The emission concentration of used vegetable oil such as formaldehyde and acrolein is two times than that of diesel fuel. However, since that of alcohol is ten times than that of used vegetable oil and that concentration is very low, it is not a problem for human health.

• Nuclear Engineering and Technology
• /
• 제55권6호
• /
• pp.2206-2214
• /
• 2023

The existing wet reconversion processes for the recovery of scraps generated in manufacturing of nuclear fuel are complex and require several unit operation steps. In this study, it is attempted to simplify the recovery process of high-quality fuel-grade UO₂ powder. A novel wet reconversion process for uranyl nitrate hexahydrate solution is suggested by using a newly developed pulsed fluidized bed reactor, and the resultant chemical characteristics are evaluated for the intermediate ammonium uranate hydrate product and subsequently converted UO₂ powder, as well as the compliance with nuclear fuel specifications and advantages over existing wet processes. The UO₂ powder obtained by the suggested process improved fuel pellet properties compared to those derived from the existing wet conversion processes. Powder performance tests revealed that the produced UO₂ powder satisfies all specifications required for fuel pellets, including the sintered density, increase in re-sintered density, and grain size. Therefore, the processes described herein can aid realizing a simplified manufacturing process for nuclear-grade UO₂ powders that can be used for nuclear power generation.

• Proceedings of the Korean Nuclear Society Conference
• /
• 한국원자력학회 2005년도 춘계학술발표회
• /
• pp.417-418
• /
• 2005

• Proceedings of the Korean Nuclear Society Conference
• /
• 한국원자력학회 2005년도 추계학술발표회
• /
• pp.342-343
• /
• 2005

• Elastomers and Composites
• /
• 제38권1호
• /
• pp.57-64
• /
• 2003

Metal oxide(MgO) was added to FKM rubber in order to develop automotive fuel hose which ran show elastic characteristics under extreme condition. Cure characteristics, physical properties, thermal resistance and fuel resistance of FKM compounded rubber with MgO were investigated. MgO was mixed to FKM rubber materials within the range of $0{\sim}20phr$. From the test results of rheological properties and Mooney viscosity, the $t_{s2}$, $T_{c90}$ values increased as the MgO contents increased in FKM rubber compounding. Hardness and 100% modulus of FKM compounded rubber slightly increased, but tensile strength and elongations at break slightly decreased. From the test results of thermal resistance of rubber specimens at 130, 150, and $170^{\circ}C$ for 70 hrs, the changing rate of physical properties was found to be relatively small. Fuel resistance tests were carried out for fuel A, B, C and D at $40^{\circ}C$ for 70hrs, and the results showed that the changing rate in physical properties was found to increase from Fuel A to D, Furthermore thermal properties of FKM compounded rubber containing MgO were also investigated by using TGA/DSC. The optimum mixing ratio of additive to FKM rubber to get the maximum effect on thermal resistance and fuel resistance, within the range of desirable specification for rubber material, was determined to be 6 phr for MgO.

• Korean Journal of Agricultural Science
• /
• 제46권4호
• /
• pp.941-953
• /
• 2019

Biodiesels are being explored as a clean energy alternative to regular diesel, which causes pollution. In this study, the optimum conditions for producing biodiesel (BD) by combining beef tallow, an animal waste resource with a high saturated fatty acid content, and corn oil, a vegetable oil with a high unsaturated fatty acid content, were investigated, and the fuel properties were analyzed. Furthermore, Multivariate Analysis of Variance (MANOVA) was used to verify the optimum conditions for producing biodiesel. The influences of control factors, such as the oil blend ratio and methanol to oil molar ratio, on the fatty acid methyl ester and biodiesel production yield were investigated. As a result, the optimum condition for producing blended biodiesel was verified to be tallow to corn oil blend ratio of 7 : 3 (TACO7) and a methanol to oil molar ratio of 14 : 1. Moreover, the interaction between the oil blend ratio and the methanol to oil molar ratio has the most crucial effects on the production of oil blended biodiesel. In conclusion, the analysis results of the fuel properties of TACO7 BD satisfied the BD quality standard, and thus, the viability of BD blended with waste tallow as fuel was verified.

• Nuclear Engineering and Technology
• /
• 제48권3호
• /
• pp.650-659
• /
• 2016

As a type of accident-tolerant fuel, fully ceramic microencapsulated (FCM) fuel was proposed after the Fukushima accident in Japan. The FCM fuel consists of tristructural isotropic particles randomly dispersed in a silicon carbide (SiC) matrix. For a fuel element with such high heterogeneity, we have proposed a two-temperature homogenized model using the particle transport Monte Carlo method for the heat conduction problem. This model distinguishes between fuel-kernel and SiC matrix temperatures. Moreover, the obtained temperature profiles are more realistic than those of other models. In Part I of the paper, homogenized parameters for the FCM fuel in which tristructural isotropic particles are randomly dispersed in the fine lattice stochastic structure are obtained by (1) matching steady-state analytic solutions of the model with the results of particle transport Monte Carlo method for heat conduction problems, and (2) preserving total enthalpies in fuel kernels and SiC matrix. The homogenized parameters have two desirable properties: (1) they are insensitive to boundary conditions such as coolant bulk temperatures and thickness of cladding, and (2) they are independent of operating power density. By performing the Monte Carlo calculations with the temperature-dependent thermal properties of the constituent materials of the FCM fuel, temperature-dependent homogenized parameters are obtained.

• Journal of ILASS-Korea
• /
• 제15권1호
• /
• pp.38-43
• /
• 2010

The LPG(Liquefied Petroleum Gas) fuel attracts attention as a clean alternative fuel. In order to further reduce the exhaust emission and improve performance in LPG engines, the LPLi(Liquid Phase LPG Injection) system is used. In LPLi system, the fuel pump performance is important for keeping the LPG over it's saturated vapor pressure. An external fuel pump is needed to improve the durability for LPG engines. This paper predicted the variation of fuel properties on the LPLi system with an external fuel pump. From each component's thermodynamic model, an 1-D simulation is developed for LPLi system with an external fuel pump. Then the 1-D simulation data analyzed and compared with the rig-test. The 1-D simulation and the rig-test produced similar results.