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Research article - Peer-reviewed, 2016

Preparation of UO2, ThO2 and (Th,U)O2 pellets from photochemically-prepared nano-powders

Pavelková, Tereza; Čuba, Václav; de Visser-Týnová, Eva; Ekberg, Christian; Persson, Ingmar


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 "ThO2 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 C yielded nano-crystalline UO2, ThO2 or solid (Th,U)O2 solutions with high purity, well-developed crystals with linear crystallite size <15 nm. The prepared nano-powders of crystalline oxides were pelletized without any binder (pressure 500 MPa), the green pellets were subsequently sintered at 1300 C under an Ar:H2 (20:1) mixture (UO2 and (Th,U)O2 pellets) or at 1600 C in ambient air (ThO2 pellets). The theoretical density of the sintered pellets varied from 91 to 97%.


Nanoparticles; Uranium(IV) oxide; Thorium oxide; UV radiation; EXAFS; Pelletizing

Published in

Journal of Nuclear Materials
2016, volume: 469, pages: 57-61

Authors' information

Pavelková, Tereza
Czech Technical University in Prague
Čuba, Václav
Czech Technical University in Prague
de Visser-Týnová, Eva
Nuclear Research and Consultancy Group (NRG)
Ekberg, Christian
Chalmers University of Technology
Swedish University of Agricultural Sciences, The Department of Chemistry and Biotechnology

UKÄ Subject classification

Inorganic Chemistry

Publication Identifiers


URI (permanent link to this page)