• Title/Summary/Keyword: Coated Fuel Particle

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MODELING FAILURE MECHANISM OF DESIGNED-TO-FAIL PARTICLE FUEL

  • Wongsawaeng, Doonyapong
    • Nuclear Engineering and Technology
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    • v.41 no.5
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    • pp.715-722
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    • 2009
  • A model to predict failure of designed-to-fail (dtf) fuel particles is discussed. The dtf fuel under study consisted of a uranium oxycarbide kernel coated with a single pyrocarbon seal coat. Coating failure was assumed to be due to fission gas recoil and knockout mechanisms and direct diffusive release of fission gas from the kernel, which acted to increase pressure and stress in the pyrocarbon layer until it ruptured. Predictions of dtf fuel failure using General Atomics' particle fuel performance code for HRB-17/18 and HFR-B1 irradiation tests were reasonably accurate; however, the model could not predict the failure for COMEDIE BD-1. This was most likely due to insufficient information on reported particle fuel failure at the beginning.

Spherical UO2 Kernel and TRISO Coated Particle Fabrication by GSP Method and CVD Technique (겔침전과 화학증착법에 의한 구형 UO2 입자와 TRISO 피복입자 제조)

  • Jeong, Kyung-Chai;Kim, Yeon-Ku;Oh, Seung-Chul;Cho, Moon-Sung
    • Journal of the Korean Ceramic Society
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    • v.47 no.6
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    • pp.590-597
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    • 2010
  • HTGR using a TRISO coated particles as nuclear raw fuel material can be used to produce clean hydrogen gas and process heat for a next-generation energy source. For these purposes, a TRISO coated particle was prepared with 3 pyro-carbon (buffer, IPyC, and OPyC) layers and 1 silicone carbide (SiC) layer using a CVD technique on a spherical $UO_2$ kernel surface as a fissile material. In this study, a spherical $UO_2$ particle was prepared using a modified sol-gel method with a vibrating nozzle system, and TRISO coating fabrication was carried out using a fluidized bed reactor with coating gases, such as acetylene, propylene, and methyltrichlorosilane (MTS). As the results of this study, a spherical $UO_2$ kernel with a sphericity of 1+0.06 was obtained, and the main process parameters in the $UO_2$ kernel preparation were the well-formed nature of the spherical ADU liquid droplets and the suitable temperature control in the thermal treatment of intermediate compounds in the ADU, $UO_3$, and $UO_2$ conversions. Also, the important parameters for the TRISO coating procedure were the coating temperature and feed rate of the feeding gas in the PyC layer coating, the coating temperature, and the volume fraction of the reactant and inert gases in the SiC deposition.

Ignition of Fuel-rich Propellant Coated with Ignition Support Material in the Ramjet Combustor Condition (램젯 연소실 조건에서 점화보조제가 도포된 Fuel-rich 추진제의 점화)

  • Jung, Woosuk;Baek, Seungkwan;Kim, Youngil;Kwon, Taesoo;Park, Juhyun;Kwon, Sejin
    • Journal of the Korean Society of Propulsion Engineers
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    • v.21 no.4
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    • pp.79-88
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    • 2017
  • Ignition test of the fuel-rich propellant coated with ignition support material in the ramjet combustor condition was conducted. Ignition delay and flame holding was measured. Fuel grain consist of HTPB mixed with AP particle 15 wt.%, Al particle 5 wt.%. To cause the short ignition delay, ignition support consist of $NC/BKNO_3$ and composite propellant was coated to the fuel grain. Ethanol blended $H_2O_2$ gas generator control the temperature, pressure, $O_2$ concentration in the oxidizer gas in the air. Gas is supplied with mass flux of $200kg/m^2s$. Through the test ignition support operated well and ignition delay of 0.6 second and the Flame was sustained.

A Study on the CVD Deposition for SiC-TRISO Coated Fuel Material Fabrication (화학증착법을 이용한 삼중 코팅 핵연료 제조에 관한 연구)

  • Kim, Jun-Gyu;Kum, E-Sul;Choi, Doo-Jin;Kim, Sung-Soon;Lee, Hong-Lim;Lee, Young-Woo;Park, Ji-Yeon
    • Journal of the Korean Ceramic Society
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    • v.44 no.3 s.298
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    • pp.169-174
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    • 2007
  • TRISO coated fuel particle is one of the most important materials for hydrogen production using HTGR (high temperature gas cooled reactors). It is composed of three isotropic layers: inner pyrolytic carbon (IPyC), silicon carbide (SiC), outer pyrolytic carbon (OPyC) layers. In this study, TRISO coated fuel particle layers were deposited through CVD process in a horizontal hot wall deposition system. Also the computational simulations of input gas velocity, temperature profile and pressure in the reaction chamber were conducted with varying process variable (i.e temperature and input gas ratios). As deposition temperature increased, microstructure, chemical composition and growth behavior changed and deposition rate increased. The simulation showed that the change of reactant states affected growth rate at each position of the susceptor. The experimental results showed a close correlation with the simulation results.

Direct Strength Evaluation of the CVD SiC Coating of TRISO Coated Fuel Particle with Micro Hemi Spherical Shell Configuration (마이크로 반구 쉘 형상의 화학증착 탄화규소 TRISO 코팅층의 파괴강도 직접평가)

  • Lee, Hyeon-Keun;Kim, Do-Kyung
    • Journal of the Korean Ceramic Society
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    • v.44 no.7
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    • pp.368-374
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    • 2007
  • CVD-SiC coating has been introduced as a protective layer in TRISO nuclear fuel particle of high temperature gas cooled reactor (HTGR) due to its excellent mechanical stability at high temperature. In order to prevent the failure of the TRISO particles, it is important to evaluate the fracture strength of the SiC coating layer. It is needed to develop a new simple characterization technique to evaluate the mechanical properties of the coating layer as a pre-irradiation step. In present work, direct strength measurement method with the specimen of hem i-spherical shell configuration was suggested. The indentation experiment on a hemisphere shell with a plate indenter was conducted. The fracture strength of the coating layer is related with the critical load for radial cracking of the shell. The finite element analysis was used to drive the semi-empirical equation for the strength measurement. The SiC hemispherical shells were successfully recovered from the section-grinding of TRISO coated particle and successive heat treatment in air. The strength of CVD-SiC coating layer was evaluated from the experimentally measured critical load during the indentation on SiC hemisphere shell. Weibull diagram of fracture strength was also constructed. This study suggested a new strength equation and experimental method to measure the fracture strength of CVD-SiC coating of TRISO coated fuel particles.

Properties of Chemical Vapor Deposited ZrC coating layer for TRISO Coated Fuel Particle (화학증착법에 의하여 제조된 탄화지르코늄 코팅층의 물성)

  • Kim, Jun-Gyu;Kum, E-Sul;Choi, Doo-Jin;Lee, Young-Woo;Park, Ji-Yeon
    • Journal of the Korean Ceramic Society
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    • v.44 no.10
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    • pp.580-584
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    • 2007
  • The ZrC layer instead of SiC layer is a critical and essential layer in TRISO coated fuel particles since it is a protective layer against diffusion of fission products and provides mechanical strength for the fuel particle. In this study, we carried out computational simulation before actual experiment. With these simulation results, Zirconium carbide (ZrC) films were chemically vapor deposited on $ZrO_2$ substrate using zirconium tetrachloride $(ZrCl_4),\;CH_4$ as a source and $H_2$ dilution gas, respectively. The change of input gas ratio was correlated with growth rate and morphology of deposited ZrC films. The growth rate of ZrC films increased as the input gas ratio decreased. The microstructure of ZrC films was changed with input gas ratio; small granular type grain structure was exhibited at the low input gas ratio. Angular type structure of increased grain size was observed at the high input gas ratio.