Alpha self-irradiation effect on the local structure of the U0.85Am0.15O2±x solid solution

Melting behaviour of americium-doped uranium dioxide

“…The (Me + Me) bond lengths are about (3.86 ± 0.01)10 À1 nm for both Am and U, indicating a random distribution in the cationic sub-lattice. One can then observe that Am and U local environments are similar to those previously reported [17,18,[45][46][47]. At the U L II edge, the Debye-Waller factors are slightly larger to those of the as-synthesized materials [17,18,20], which suggests a higher structural disorder and agrees with the slight hyper-stoichiometry.…”

“…However, because a delay of few weeks (for XRD) to a couple of months (for XAS) was inevitable between the laser heating/cooling treatments and the post-melting material characterisation, the samples underwent some self-irradiation damage, notably those with the highest Am content. This could be viewed as a partial explanation for the complex phase splitting and higher O/M ratio observed in the U 0.8 Am 0.2 O 2+d sample as several studies have shown that a-selfirradiation-induced structural effects on (U, Am)O 2 compounds are limited to lattice swelling reaching up to 0.8 vol.% and a small structural disorder increase [45,46,[52][53][54].…”

Comparative XRPD and XAS study of the impact of the synthesis process on the electronic and structural environments of uranium–americium mixed oxides

“…The Me-Me bond lengths are about 3.86(1) Å for both Am and U, indicating the metal lattice is little perturbed from the ideal crystallographic positions and that a random distribution in the cationic sublattice is likely. One can then observe that Am and U local environments are similar to those previously reported [20][21][22] and are not dependent on the synthesis process. However, two differences with the work of Vespa et al [11] can be noted.…”

“…In addition to the three single scattering paths (Me-O, Me-Me and Me-O), one multiple-scattering path (Me-OMe-O-Me) was also considered in the FEFF calculations. As often employed for An L III /L II [19][20][21][22][23][24][25], the amplitude factor (S 0 2 ) was set at 0.90 for U and Am shells. The shift in the threshold energy (ΔE 0 ) was varied as a global parameter.…”

α Self-irradiation Effects on Structural Properties of (U,Am)O2±δMaterials

“…It consists in the irradiation Ambearing blankets (AmBB, i.e., U 1-x Am x O 2±δ with x values close to 10-15 at.%) in the periphery of a fast neutron reactor core. In this context, studies are being performed to assess the feasibility and safety of AmBB transmutation, notably focusing on innovative fabrication processes [1][2][3] Am being a strong α emitter (activity of 130 MBq), U 1-x Am x O 2±δ behavior under α self-irradiation is also monitored [6][7][8].…”