Structural investigation on an aged americium transmutation fuel

Within the EFTTRA-T4 project a MgAl2O4 based inert matrix fuel for 241Am transmutation was produced in 1996. Am L3-edge EXAFS of the annealed material indicate that Am is present as AmAlO3. During 10 years of storage the material accumulated self-irradiation damage and no AmAlO3 X-ray diffraction features can be observed, indicating amorphization of the aged material by the corresponding cumulative α-damage of 2.9 × 1019 g−1 AmAlO3. The Am L3-edge EXAFS of the amorphous AmAlO3 shows that structural order is limited to the first oxygen shell around Am, where the rhombohedral splitting in three sub-shells is still present. Evidence for a single Al atom in the next shell is found at an Am–Al distance of 3.28 Å.