Preparation and microstructural characterization of silicate and borosilicate glasses containing cerium or plutonium

The preparation of Pu-containing silicate and borosilicate glasses, referring to the conditioning of alpha contaminated and of high level waste, respectively, has been studied. The preparation of a typical borosilicate glass did not give rise to problems regarding to pouring and final homogeneity of the glass. The preparation of silicate glasses, however, was much more difficult, since at the melting temperatures available these glasses could not be poured, and showed pronounced heterogeneities. Different melting parameters, such as melting time and physico-chemical preparation of the melting batch were investigated in order to improve the homogeneity. None of these parameters had a marked beneficial influence upon the homogeneity. Chemical attack of the alumina crucible by the glass was found to be the main reason for the heterogeneities observed. Preliminary observations suggest that PuO2 has been dissolved in the glass matrix. (author)