- Characteristics of the Ammonium Diuranate Powders Prepared with Different Experimental Apparatus in Sol-gel Process
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Yeon-Ku Kim, Kyung-Chai Jeong, Sung-Ho Ueom, Moon Sung Cho
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J Korean Powder Metall Inst. 2012;19(6):398-404.
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DOI: https://doi.org/10.4150/KPMI.2012.19.6.398
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- This paper describes the spherical ammonium diuranate gel particles which are the intermediated material of the UO_2 microsphere for an VHTR(very high temperature reactor) nuclear fuel. The characteristics of the intermediate-ADU gel particles prepared by AWD(ageing, washing, and drying) and FB(fluidized-bed) apparatus were examined and compared in a sol-gel fabrication process. The electrical conductivity of washing filtrate from the FB treating and the surface area of dried-ADU gel particles were higher than those of AWD treating. Also, an internal pore volume in dried-ADU gel particles showed a more decrease in AWD treatment than FB treatment because of decomposition of PVA affected by the washing time. However, the internal microstructures of ADU gel particles were similar regardless of the process variation.
- Effects of Process Parameters on the Powder Characteristics of Uranium Oxide Kernel Prepared by Sol-gel Process
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Yeon-Ku Kim, Kyung-Chai Jeong, Seung-Chul Oh, Dong-Soo Suhr, Moon-Sung Cho
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J Korean Powder Metall Inst. 2009;16(4):254-261.
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DOI: https://doi.org/10.4150/KPMI.2009.16.4.254
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- In this study, we investigated the unit process parameters in spherical UO_2 kernel preparation. Nearly perfect spherical UO_3 microspheres were obtained from the 0.6M of U-concentration in the broth solution, and the microstructure of the UO_2 kernel appeared the good results in the calcining, reducing, and sintering processes. For good sphericity, high density, suitable microstructure, and no-crack final UO_2 microspheres, the temperature control range in calcination process was 300sim450°C, and the microstructure, the pore structure, and the density of UO_2 kernel could be controlled in this temperature range. Also, the concentration changes of the ageing solution in aging step were not effective factor in the gelation of the liquid droplets, but the temperature change of the ageing solution was very sensitive for the final ADU gel particles.
- Effects of Thermal Treatment Conditions on the Powder Characteristics of Uranium Oxide in HTGR Fuel Preparation
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Yeon-Ku Kim, Kyung-Chai Jeong, Seung-Chul Oh, Dong-Soo Suhr, Moon-Sung Cho
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J Korean Powder Metall Inst. 2009;16(2):115-121.
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DOI: https://doi.org/10.4150/KPMI.2009.16.2.115
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- The effects of thermal treatment conditions on ADU (ammonium diuranate) prepared by SOL-GEL method, so-called GSP (Gel supported precipitation) process, were investigated for UO_2 kernel preparation. In this study, ADU compound particles were calcined to UO_3 particles in air and Ar atmospheres, and these UO_3 particles were reduced and sintered in 4%-H_2/Ar. During the thermal calcining treatment in air, ADU compound was slightly decomposed, and then converted to UO_3 phases at 500°C. At 600°C, the U_3O_8 phase appeared together with UO_3. After sintering of theses particles, the uranium oxide phases were reduced to a stoichiometric UO_2. As a result of the calcining treatment in Ar, more reduced-form of uranium oxide was observed than that treated in air atmosphere by XRD analysis. The final phases of these particles were estimated as a mixture of U_3O_7 and U_4O_9.
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