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U.S. Department of Energy
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The release of technetium from defense waste processing facility glasses

Conference ·
OSTI ID:219243
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 {Tc} 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{sup {minus}1} and have been completed through 1822 days. The formation of certain alteration phases in tests at 2000 and 20,000 m{sup {minus}1} results in an increase in the dissolution rates of both classes. The release of {Tc} 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 ,{sup {minus}1}, the {Tc} 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 {Tc}(VII) to {Tc}(IV) may have precipitated, thou-h the amount of {Tc} was too low to detect any {Tc}-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.
Research Organization:
Argonne National Lab., IL (United States)
Sponsoring Organization:
USDOE, Washington, DC (United States)
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
219243
Report Number(s):
ANL/CMT/CP--86953; CONF-951155--63; ON: DE96007206
Country of Publication:
United States
Language:
English