[en] Industrial development of nuclear waste glass processing requires basic data on glass vaporization thermodynamics. Detailed mass spectrometric experiments and thermodynamic estimates have been made for vaporization of a nonradioactive borosilicate glass containing representative nuclear waste isotopes. Alkali metaborates were observed to be the dominant vapor species and their partial pressures indicate significant vapor transport under likely process conditions. The results indicate the following order of significance for vapor transport of radionuclide species, Cs about equal to Re (about equal to Tc) > Ru >> Sr