Determing precisely the structural phases present of aged Ln doped UO2 nanoparticles via HR-PXRD measurements

In the present proposal HR-PXRD are sort of BM20 to determine the structural phases of aged Ln doped UO2 nanoparticles. Such nanoparticles are found after a high burn-up time of UO2 and referred to as high burnup structures (HBS) which is a part of spent nucleal fuel (SNF). Based on Lab. PXRD measurements it was shown that the aged samples occur in two phases: The UO2 phase (Space group Fm-3-m) and metaschoepite-phases. But it is not clear what extent lanthanides influence the oxidation process of UO2 nanoparticles and how this affects the formation of metaschoepite-phases or further crystal structures. High resolution PXRD measurements are subsequently required to determine precise structures of the metaschoepite phase using the Rietveld method. This work has implications for the storage and safety of SNF particularly in the context of the “instance release fraction” in which caesium is a part of and to draw appropriate conclusions for the storage of SNF.