Leaching Tc-99 from SRP glass in simulated tuff and salt groundwaters

Conference · Thu Jan 01 04:00:00 EST 1987

OSTI ID:60419

Bibler, N E; Jurgensen, A R

Results of leach tests with Tc-99 doped SRP borosilicate waste glass are presented. The glass was prepared by melting a mixture of SRP 165 powdered frit doped with a carrier free solution of Tc-99 at 1150{sup 0}C. Dissolution of portions of the resulting glass indicated that the Tc-99 was distributed homogeneously throughout the glass. Static leach tests up to 90 days were performed at 90{sup 0}C in J-13 tuff groundwater or WIPP brine A at a SA/V of 100m{sup -1}. Normalized mass losses were calculated for Tc-99 as well as all the major elements in the glass. Results indicated that under ambient oxidizing conditions Tc-99 leached no faster than the glass-forming elements of the glass. In J-13 water, Tc-99 leached congruently with B. In WIPP brine A, it leached congruently with Si. Leach rates for Li were higher in both groundwaters, probably due to a contribution from an ion exchange mechanism. Leach tests were performed under reducing conditions in J-13 water by adding Zn/Hg amalgam to the leachate. In these tests the pH increased significantly, probably because of the reaction of the amalgam with the water. In a 21-day test, the pH increased to 13 and leach rates for the glass were very high. Even though there was signifcant dissolution of the glass, the normalized mass loss based on Tc-99 was only 0.02g/m{sup 2}. This result and the fact that reducing conditions at normal pH values do not significantly affect the dissolution of the glass, indicate that the low concentrations for Tc-99 obtained under reducing conditions are due to is solubility and not due to an increased durability of the glass. 14 refs., 2 figs., 5 tabs.

• Research Organization: Savannah River Lab., Aiken, SC (United States)
• DOE Contract Number: AC09-76SR00001
• OSTI ID: 60419
• Report Number(s): DP-MS--87-70; CONF-871124--52; ON: DE88004740
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
54 ENVIRONMENTAL SCIENCES
BOROSILICATE GLASS
BRINES
GROUND WATER
HIGH-LEVEL RADIOACTIVE WASTES
LEACHING
PH VALUE
RADIONUCLIDE MIGRATION
SOLUBILITY
TECHNETIUM 99
TUFF
UNDERGROUND DISPOSAL
VITRIFICATION
Yucca Mountain Project