Application of SPS in the fabrication of UN and (U,Th)N pellets from microspheres
Journal article, 2020

In this study, the process involved in the fabrication of a potential accident tolerant fuel is described. Homogeneous uranium nitride microspheres doped with different thorium content were successfully manufactured using an internal gelation process followed by carbothermic reduction, and nitridation. Elemental analysis of the materials showed low carbon and oxygen content, the two major impurities found in the products of carbothermic reduction. Uranium nitride microspheres were pressed and sintered using spark plasma sintering (SPS) to produce pellets with variable density. Final density can be tailored by choosing the sintering temperature, pressure and time. Density values of 77–98% of theoretical density (%TD) were found. As expected, higher temperatures and pressures resulted in a denser material. Furthermore, a direct correlation between the onset sintering temperature and thorium content in the materials was observed. The change of onset temperature has been related to an increment in the activation energy for self-diffusion due to the substitution of uranium atoms by thorium in the crystal structure.


Theoretical density




Internal gelation


Uranium nitride


Luis Guillermo Gonzalez Fonseca

Chalmers, Chemistry and Chemical Engineering, Energy and Material

Marcus Hedberg

Chalmers, Chemistry and Chemical Engineering, Energy and Material

L. Huan

Royal Institute of Technology (KTH)

P. Olsson

Royal Institute of Technology (KTH)

Teodora Retegan Vollmer

Chalmers, Chemistry and Chemical Engineering, Energy and Material

Journal of Nuclear Materials

0022-3115 (ISSN)

Vol. 536 152181

Subject Categories


Materials Chemistry

Condensed Matter Physics



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6/3/2020 5