Abstract
This article focuses on the Am incorporation and location in the UMo-glass ceramic designed to manage fission product solutions enriched in 241Am generated by the reprocessing of UMo spent fuel. This type of glass ceramic contains crystalline phases, which are phosphates, molybdates and zircons, embedded in a durable borosilicate glass matrix.Two types of UMo-glass ceramics were considered in this study. One type of samples was doped with different amounts of Am and/or Nd to assess the comparative role of Nd versus Am in terms of incorporation, location and microstructure. A second type of sample was doped with 244Cm, in order to specify the behavior of 244Cm compared with that of Nd and Am, with a view to using this short-lived isotope for aging experiments.These matrices were characterized by gamma spectrometry and isothermal calorimetry to check the overall homogeneity of Am and Cm, then by Raman spectroscopy, SEM, EPMA and XRD to determine the microstructure and the actinide/Nd distribution in the different phases. The microstructure of the samples was heterogeneous as expected, with the presence of phosphate, molybdate and zircon crystalline phases. A great enrichment of Am, Cm and Nd was observed in the phosphate and molybdate phases compared to the embedding glassy matrix and the zircon crystals. A partition coefficient of around x 6 – 7 for Am and Nd was calculated in these two crystalline phases compared to the mean target doping value. Finally, Nd behaved like trivalent actinides in the UMo matrix and could therefore be considered as a relevant surrogate.
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