Chemical durability of glass containing SRP waste: leachability characteristics, protective layer formation, and repository system interactions

The Repository Systems Program at Savannah River consists of the following elements: (a) static repository tests, (b) slow flow groundwater tests, (c) dynamic leaching experiments, (d) long term leaching tests, and (e) in situ experiments. The scouting tests performed in the static repository program are summarized and a new dynamic leaching concept is introduced in this paper. Abbreviated MCC-1 static leaching tests were used in this static repository program. The tests were conducted at 90/sup 0/C for 7 days with deionized water as well as repository groundwaters as leachants. The static repository program consisted of three phases. Phase 1 of the study evaluated the leachability of SRP waste glass leached in the presence of salt, basalt, shale, granite, and tuff at three different ratios of surface areas of sample to volume of leachant (SA/V). These data were then compared to tests on similar glasses leached in the absence of rock. The second phase of this program evaluated the effects of five simulated groundwaters on the leachability of waste glass both with and without host rock present and compared these results to glass leached by deionized water. The groundwaters included many minor as well as major constituents. The third and final phase of the program evaluated waste glass leachability as a function of tests conducted in the presence of candidate canister and overpack metals, backfill mixtures, and five complete package systems. The sample matrices are given in Table 2 and the data are summarized