Improved doping and densification of uranium oxide microspheres using starch as pore former

Gamze Çolak; Gregory Leinders; Rémi Delville; Marc Verwerft; Jef Vleugels

doi:10.1016/j.jnucmat.2023.154319

Improved doping and densification of uranium oxide microspheres using starch as pore former

Gamze Çolak, Gregory Leinders, Rémi Delville, Marc Verwerft, Jef Vleugels

Research output › peer-review

Abstract

A hybrid route combining internal gelation and a single-step infiltration was investigated to prepare U _1-yNd _yO _2-x sintered microspheres as a surrogate for U _1-yAm _yO _2-x transmutation targets. This simplified procedure eliminates the use of successive infiltration and re-calcination steps to reach higher dopant concentrations. The use of starch as a pore-forming agent in the internal gelation process for fabricating porous uranium oxide microspheres has been studied in detail to improve the conditions for an efficient infiltration with dopant solution. While the crystalline structure and composition of dried microspheres was not significantly affected by the process conditions, the onset of the UO ₃ to U ₃O ₈ phase transformation during calcination is shifted from 803 K to 823 K when starch was used. Biphasic mixtures of β-UO ₃ and α-U ₃O ₈ were formed when calcination temperatures between 833 and 853 K were applied. High accessible porosity levels (26–33%) were measured after calcination, and this resulted in efficient infiltration behavior allowing to reach average dopant levels up to y = 30 mol% after sintering. Microstructural features of the sintered microspheres (grain size, porosity distribution, dopant homogeneity) are discussed.

Original language	English
Article number	154319
Number of pages	11
Journal	Journal of Nuclear Materials
Volume	577
DOIs	https://doi.org/10.1016/j.jnucmat.2023.154319
State	Published - 15 Apr 2023

ASJC Scopus subject areas

Materials Science(all)
Nuclear and High Energy Physics
Nuclear Energy and Engineering

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Cite this

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title = "Improved doping and densification of uranium oxide microspheres using starch as pore former",

abstract = "A hybrid route combining internal gelation and a single-step infiltration was investigated to prepare U 1-yNd yO 2-x sintered microspheres as a surrogate for U 1-yAm yO 2-x transmutation targets. This simplified procedure eliminates the use of successive infiltration and re-calcination steps to reach higher dopant concentrations. The use of starch as a pore-forming agent in the internal gelation process for fabricating porous uranium oxide microspheres has been studied in detail to improve the conditions for an efficient infiltration with dopant solution. While the crystalline structure and composition of dried microspheres was not significantly affected by the process conditions, the onset of the UO 3 to U 3O 8 phase transformation during calcination is shifted from 803 K to 823 K when starch was used. Biphasic mixtures of β-UO 3 and α-U 3O 8 were formed when calcination temperatures between 833 and 853 K were applied. High accessible porosity levels (26–33%) were measured after calcination, and this resulted in efficient infiltration behavior allowing to reach average dopant levels up to y = 30 mol% after sintering. Microstructural features of the sintered microspheres (grain size, porosity distribution, dopant homogeneity) are discussed.",

keywords = "Uranium microspheres, Internal gelation, Starch, Porosity, infiltration, Neodymium, transmutation, Infiltration",

author = "Gamze {\c C}olak and Gregory Leinders and R{\'e}mi Delville and Marc Verwerft and Jef Vleugels",

note = "Score=10 Funding Information: The authors gratefully acknowledge Koen Vanaken and Peter Dries for their assistance in the laboratory. Gamze Colak thanks Tommy Mai for his help during data curation of SEM investigations and the Energy Transition Fund of the Belgian FPS Economy (project: ASOF – Advanced Separation for Optimal management of Spent Fuel) for the financial support of this research. Publisher Copyright: {\textcopyright} 2023",

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AU - Leinders, Gregory

AU - Delville, Rémi

AU - Verwerft, Marc

AU - Vleugels, Jef

N1 - Score=10 Funding Information: The authors gratefully acknowledge Koen Vanaken and Peter Dries for their assistance in the laboratory. Gamze Colak thanks Tommy Mai for his help during data curation of SEM investigations and the Energy Transition Fund of the Belgian FPS Economy (project: ASOF – Advanced Separation for Optimal management of Spent Fuel) for the financial support of this research. Publisher Copyright: © 2023

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Y1 - 2023/4/15

N2 - A hybrid route combining internal gelation and a single-step infiltration was investigated to prepare U 1-yNd yO 2-x sintered microspheres as a surrogate for U 1-yAm yO 2-x transmutation targets. This simplified procedure eliminates the use of successive infiltration and re-calcination steps to reach higher dopant concentrations. The use of starch as a pore-forming agent in the internal gelation process for fabricating porous uranium oxide microspheres has been studied in detail to improve the conditions for an efficient infiltration with dopant solution. While the crystalline structure and composition of dried microspheres was not significantly affected by the process conditions, the onset of the UO 3 to U 3O 8 phase transformation during calcination is shifted from 803 K to 823 K when starch was used. Biphasic mixtures of β-UO 3 and α-U 3O 8 were formed when calcination temperatures between 833 and 853 K were applied. High accessible porosity levels (26–33%) were measured after calcination, and this resulted in efficient infiltration behavior allowing to reach average dopant levels up to y = 30 mol% after sintering. Microstructural features of the sintered microspheres (grain size, porosity distribution, dopant homogeneity) are discussed.

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KW - Uranium microspheres

KW - Internal gelation

KW - Starch

KW - Porosity

KW - infiltration

KW - Neodymium

KW - transmutation

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