[en] Laboratory tests are being, conducted using two radionuclide-doped Defense Waste Processing, Facility (DWPF) glasses (referred to as SRL 13IA and SRL 202A) to characterize the effects of the glass surface area/solution volume (SN) ratio on the release and disposition of T_c and several actinide elements. Tests are being conducted at 90 degrees C in a tuff ground water solution at SN ratios of 10, 2000, and 20,000 m^-1 and have been completed through 1822 days. The formation of certain alteration phases in tests at 2000 and 20,000 m^-1 results in an increase in the dissolution rates of both classes. The release of T_c parallels that of B and Na under most test conditions and its release increases when alteration phases form. However, in tests with SRL 202A glass at 20,000 ,^-1, the T_c concentration in solution decreases coincidentally with an increase in the nitrite/nitrate ratio that indicates a decrease in the solution Eh. This may have occurred due to radiolysis, glass dissolution, the formation of alteration phases, or vessel interactions. Technetium that was reduced from T_c(VII) to T_c(IV) may have precipitated, thou-h the amount of T_c was too low to detect any T_c-bearing phases. These results show the importance of conducting long-term tests with radioactive glasses to characterize the behavior of radionuclides, rather than relying on the observed behavior of nonradioactive surrogates