Two-year leaching behavior of three SRL nuclear waste glasses in granite

Two-year burial experiments on three Savannah River Laboratory (SRL) simulated nuclear waste glasses were conducted to evaluate their resistance to ground-water attack under repositorylike conditions. Glass samples were buried in the boreholes at the 345-m level in the Stripa granite at either 80 to 100 or 900C. The leached surfaces were characterized using SEM-EDS, FT-IRRS, SIMS, and optical microscopy. Leach depths of buried samples based on alkali extraction at 900C range from 0.3 to 1.8 μm/year for the glass/glass interfaces of the three glass formulations. These values are at least two orders of magnitude lower than those for glasses leached using MCC static leaching procedures and deionized water. Results also show that durabilities of the SRL composite nuclear waste glass were increased by approximately six times when frit 131 was substituted by frit 165. An increase of waste loading of SRL 131 glass from 29.8 to 35 wt% decreases leachabilities by a factor of 2