Preparation of UO sub(2), ThO sub(2) and (Th,U)O sub(2) pellets from photochemically-prepared nano-powders

Photochemically-induced preparation of nano-powders of crystalline uranium and/or thorium oxides and their subsequent pelletizing has been investigated. The preparative method was based on the photochemically induced formation of amorphous solid precursors in aqueous solution containing uranyl and/o...

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Bibliographic Details
Published in:Journal of nuclear materials 2016-02, Vol.469, p.57-61
Main Authors: Pavelkova, Tereza, Cuba, Vaclav, de Visser-Tynova, Eva, Ekberg, Christian, Persson, Ingmar
Format: Article
Language:English
Subjects:
Crystal structure
Heat treatment
Irradiation
Nanostructure
Pellets
Precursors
Sintering
Uranium
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Summary:Photochemically-induced preparation of nano-powders of crystalline uranium and/or thorium oxides and their subsequent pelletizing has been investigated. The preparative method was based on the photochemically induced formation of amorphous solid precursors in aqueous solution containing uranyl and/or thorium nitrate and ammonium formate. The EXAFS analyses of the precursors shown that photon irradiation of thorium containing solutions yields a compound with little long-range order but likely "ThO sub(2) like" and the irradiation of uranium containing solutions yields the mixture of U(IV) and U(VI) compounds. The U-containing precursors were carbon free, thus allowing direct heat treatment in reducing atmosphere without pre-treatment in the air. Subsequent heat treatment of amorphous solid precursors at 300-550 degree C yielded nano-crystalline UO sub(2), ThO sub(2) or solid (Th,U)O sub(2) solutions with high purity, well-developed crystals with linear crystallite size
ISSN:0022-3115
DOI:10.1016/j.jnucmat.2015.11.041