ABSTRACT. A borosilicate glass, containing 25 wt. % of simulated high-level radioactive waste has been reacted with water at 350 ~ and 500 bars for 14 and 48 days using large-volume 'cold-seal' high-pressure equipment. Under these conditions the glass crystallizes a suite of mineral phases including: albite, NaA1Si3Os; aegirine, NaFeSi206; riebeckite, Na2Fez(Fe,Mg)aSisOE2(OH)2; zektzerite, LiNaZrSirOls; barium strontium molybdate, (Ba,Sr) MOO4; stillwellite, (Nd,Ce,La)BSiOs; willemite, ZnzSiO4; smectite; a lithium-sodium borosilicate hydrate; melilite (fikermanite), Ca2MgSi20 7. A description of the morphology of these phases is given, together with a number of chemical analyses. The implications of the incorporation of waste species in these mineral phases to the disposal of high-level radioactive waste is discussed.
K E V W O R D S:radioactive waste, borosilicate glass, albite, aegirine, riebeckite, zektzerite, stillwellite, willemite, smectite, melilite.