Chemical alteration of 238Pu-loaded borosilicate glass under saturated leaching conditions

Highly radioactive ²³⁸Pu-doped and non-radioactive samples of borosilicate glass with chemical compositions and synthesis routine similar to SON68 glass were studied under static saturated leaching conditions in distilled water at 90 °C. Dramatic differences in behavior of the radioactive and model glasses were observed. On time scale of 4 months the radioactive glass is fully covered by mechanically unstable alteration layer, possibly consisting of aluminum hydroxides with small fraction of a separate secondary Pu bearing phase. The model glass remains virtually pristine. Addition of Eu³⁺ into the glass allowed examination of the glass radio- and photoluminescence and to assess changes or REE³⁺ impurity local environment during self-irradiation and leaching. Photoluminescence spectra suggest more ordered local environment of europium ions in the alteration “gel” than in the bulk glass. Peculiar behavior of the photoluminescence spectra excited at different laser power is observed for the alteration layer and is ascribed to optical bleaching of color centers.