XANES analysis of a Cm-doped borosilicate glass under α-self-irradiation effects

Industrial borosilicate glasses containing fission products and minor actinides can be subjected to structural damage caused mainly by alpha-self-irradiation effects. In this field of glasses under extreme conditions, we present an X-ray Absorption Near-Edge Structure investigation of two six-oxide borosilicate curium-doped glasses (based on the International Simplified Glass (ISG) composition). The first sample is an 8-year ISG damaged glass, which has already accumulated an alpha-decay dose greater than 6.10(18) alpha g(-1), a value corresponding to a damaged but stabilized structural state. The second sample results from annealing of the latter ISG damaged glass. Three species, Cm, Pu and Zr were probed at L-3-edge, L-3-edge and K-edge, respectively. From the experimental results, Cm and Pu species appear respectively in +3 and +4 oxidation states in both glasses. No Cm local environment changes are observed. In contrast, a small variation in Pu local environment appears between the damaged and annealed glasses, reflecting a possible coordination variation or Pu-Zr substitution. A more drastic effect appears for Zr local environment, where a sevenfold coordinated site grows over time under alpha-self-irradiation effects, at the expense of the initial major sixfold site of symmetry. Moreover, annealing the damaged glass does not permit to retrieve a similar structural state to the one of a just melted curium-doped ISG.