Stimulation of densification during the reduction of U3O8 to UO2 by atmosphere control

A reduction process in the head-end for pyroprocessing has been adopted to avoid oxidation attack on the molybdenum crucible during sintering. The reduction process is employed to reduce U3O8 pellets to UO2 prior to sintering. This allows elimination of the oxygen source, which causes oxidation atta...

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Bibliographic Details
Published inCeramics international Vol. 45; no. 6; pp. 6863 - 6868
Main Authors Jeon, Sang-Chae, Lee, Jae-Won, Yoon, Joo-Young, Cho, Yung-Zun, Kim, Dong-Joo, Kim, Dong Seok, Kim, Keon Sik, Kim, Jong Hun, Yang, Jae Ho
Format Journal Article
LanguageEnglish
Published Elsevier Ltd 15.04.2019
Subjects
Densification
Head-end
Pyroprocessing
Reduction kinetics
U3O8
UO2
U3O8
Head-end
Reduction kinetics
UO2
Densification
Pyroprocessing
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Summary:A reduction process in the head-end for pyroprocessing has been adopted to avoid oxidation attack on the molybdenum crucible during sintering. The reduction process is employed to reduce U3O8 pellets to UO2 prior to sintering. This allows elimination of the oxygen source, which causes oxidation attack during sintering, thereby permitting the use of a metallic crucible. However, little densification occurs due to the low reduction temperature limited by the INCONEL crucible. Consequently, the amount of material scraps from the pellets increases, thus creating an additional processing burden due to its high radioactivity. To reduce the amount of scraps, densification should be enhanced. This study suggests a simple atmospheric control strategy and clarifies its effects. With the atmospheric control, a higher bulk density and better attrition resistance were obtained in comparison to without this strategy. This can be explained in terms of O/U ratio dependent diffusion kinetics during the reduction of U3O8 to UO2.
ISSN:0272-8842
1873-3956
DOI:10.1016/j.ceramint.2018.12.181