Characterization of uranium neodymium oxide microspheres synthesized by internal gelation

Abstract

In the context of advanced nuclear fuel cycles including partitioning and transmutation (P&T), actinide co-conversion processes play an important role to close the loop. Therefore, actinides are embedded in ceramics to be used as precursors for the fabrication of fuels. The sol–gel route by internal gelation is a suitable and dust-free conversion method. Furthermore, the required spherical particles are already formed at the gel stage.Pure UO2 microspheres and U/Nd oxide particles with a variable content of Nd (5–40%) were fabricated by internal gelation. Acid deficient uranyl nitrate and Nd nitrate solutions were used as precursor for the microsphere fabrication. Neodymium is used as a surrogate for trivalent actinides, such as americium. Mass- and diameter-distributions were studied and particle densities were calculated. Finally, the microspheres were thermally treated in a reducing H2:Ar gas atmosphere at 1573 K.The solid solutions of UO2 and Nd2O3 were investigated by scanning electron microscopy and X-ray powder diffraction. The obtained reflexes are indicating one cubic phase. Lattice parameter calculations were performed, the results depend linear on the Nd content up to ≈ 30%. Particle compositions containing more Nd are showing an unexpected behavior.