• Title/Summary/Keyword: uranium oxide

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Crystallite Size Measurement of Uranium Oxide Fuel Powders by Neutron Diffraction (중성자 회절에 의한 산화우라늄 핵연료 분말의 결정크기 측정)

  • 류호진;강권호;문제선;송기찬;최용남
    • Journal of Powder Materials
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    • v.10 no.5
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    • pp.318-324
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    • 2003

  • The nano-scale crystallite sizes of uranium oxide powders in simulated spent fuel were measured by the neutron diffraction line broadening method in order to analyze the sintering behavior of the dry process fuel. The mixed $UO_2$ and fission product powders were dry-milled in an attritor for 30, 60, and 120 min. The diffraction patterns of the powders were obtained by using the high resolution powder diffractometer in the HANARO research reactor. Diffraction line broadening due to crystallite size was measured using various techniques such as the Stokes' deconvolution, profile fitting methods using Cauchy function, Gaussian function, and Voigt function, and the Warren-Averbach method. The non-uniform strain, stacking fault and twin probability were measured using the information from the diffraction pattern. The realistic crystallite size could be obtained after separation of the contribution from the non-uniform strain, stacking fault and twin.

  • https://doi.org/10.4150/KPMI.2003.10.5.318 인용 PDF KSCI

Application of Phase-Field Theory to Model Uranium Oxide Reduction Behavior in Electrolytic Reduction Process (전해환원 공정의 우라늄 산화물 환원 거동 모사를 위한 Phase-Field 이론 적용)

  • Park, Byung Heung;Jeong, Sang Mun
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.16 no.3
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    • pp.291-299
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    • 2018

  • Under a pyro-processing concept, an electrolytic reduction process has been developed to reduce uranium oxide in molten salt by electrochemical means as a part of spent fuel treatment process development. Accordingly, a model based on electrochemical theory is required to design a reactor for the electrolytic reduction process. In this study, a 1D model based on the phase-field theory, which explains phase separation behaviors was developed to simulate electrolytic reduction of uranium oxide. By adopting parameters for diffusion of oxygen elements in a pellet and electrochemical reaction rate at the surface of the pellet, the model described the behavior of inward reduction well and revealed that the current depends on the internal diffusion of the oxygen element. The model for the electrolytic reduction is expected to be used to determine the optimum conditions for large scale reactor design. It is also expected that the model will be applied to simulate the integration of pyro-processing.

  • https://doi.org/10.7733/jnfcwt.2018.16.3.291 인용 PDF KSCI

Study on the Fabrication of Porous Uranium Oxide Granule Using a Rotary Voloxidizer (회전형 휘발성 산화장치 이용 다공성 우라늄산화물 그래뉼 제조 연구)

  • Lee, Jae-Won;Yun, Yeo-Wan;Shin, Jin-Myeong;Lee, Jung-Won;Park, Guen-IL;Park, Jang-Jin
    • Applied Chemistry for Engineering
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    • v.22 no.6
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    • pp.642-647
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    • 2011

  • The fabrication characteristics of porous uranium oxide granules from $U_3O_8$ powder was investigated in terms of initial particle bed motions such as slumping and rolling, thermal treatment conditions, and rotational velocities in slumping motion using a rotary voloxidizer. With respect to the initial particle bed motion the recovery rate of granule of above 1 mm in slumping motion was higher than that in the rolling motion. Rolling motion was changed into slumping motion with high slumping frequency by formation of granules from fine particles. Recovery rate of granule significantly increased with the increas in thermal treatment temperature and time of upto 10 h. As the rotational velocity of voloxidizer in the case of the initial particle bed showing slumping motion increased, the recovery rate of granule increased from 81.5 to 88.7%. However, the rotational velocity of 2 rpm provided an effective density, crushing strength and sphericity of granules.

  • https://doi.org/10.14478/ace.2011.22.6.642 인용 PDF KSCI

Improvement of Pilot-scale Electrokinetic Remediation Technology for Uranium Removal (우라늄 제거를 위한 실험실 규모 동전기 장치의 개선 방안)

  • Park, Hye-Min;Kim, Gye-Nam;Kim, Seung-Soo;Kim, Wan-Suk;Park, Uk-Ryang;Moon, Jei-Kwon
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.11 no.2
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    • pp.77-83
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    • 2013

  • The original pilot-scale electrokinetic equipment suitable to soil contamination characteristics of Korean nuclear facility sites was manufactured for the remediation of soil contaminated with uranium. During the experiment with the original electrokinetic equipment, many metal oxides were generated and were stuck on the cathode plate. The uranium removal capability of the original electrokinrtic equipment was almost exhausted because the cathode plate covered with metal oxides did not conduct electricity in the original electrokinetic equipment. Therefore, the original electrokinetic equipment was improved. After the remediation experience for 25 days using the improved electrokinetic remediation equipment, the removal efficiency of uranium from the soil was 96.8% and its residual uranium concentration was 0.81 Bq/g. When the initial uranium concentration of soil was about 50 Bq/g, the electrokinetic remediation time required to remediate the uranium concentration below clearance concentration of 1.0 Bq/g was about 34 days. When the initial uranium concentration of soil was about 75 Bq/g, the electrokinetic remediation time required to remediate below 1.0 Bq/g was about 42 days. When the initial uranium concentration of soil was about 100 Bq/g, the electrokinetic remediation time required to remediate below 1.0 Bq/g was about 49 days.

  • https://doi.org/10.7733/jkrws.2013.11.2.77 인용 PDF KSCI