Leaching of actinide-doped nuclear waste glass in a tuff-dominated system
A laboratory leaching test has been performed as part of a project to evaluate the suitability of tuff rocks at Yucca Mountain, Nevada, as a site for a high-level nuclear waste repository. Glass samples were placed in water inside tuff vessels, and then the tuff vessels were placed in water inside Teflon containers. Glass-component leach rates and migration through the tuff were measured for samples of the ATM-8 actinide glass, which is a PNL 76-68 based glass doped with low levels of {sup 99}Tc, {sup 237}Np, {sup 238}U, and {sup 239}Pu to simulate wastes. Disc samples of this glass were leached at 90{sup 0}C for 30, 90, and 183 days inside tuff vessels using a natural groundwater (J-13 well-water) as the leachant. At the end of each leaching interval, the J-13 water present inside and outside the rock vessel was analyzed for glass components in solutions. Boron, molybdenum, and technetium appear to migrate through the rock at rates that depend on the porosity of each vessel and the time. The actinide elements were found only in the inner leachate. Normalized elemental mass loss values for boron, molybdenum, and technetium were calculated using concentrations of the inner and outer leachates and assuming a negligible retention on the rock. The maximum normalized release was 2.3 g/m{sup 2} for technetium. Boron, molybdenum, technetium, and neptunium were released linearly with respect to each other, with boron and molybdenum released at about 85% of the technetium rate, and neptunium at 5 to 10% of the technetium rate. Plutonium was found at low levels in the inner leachate but was strongly sorbed on the steel and Teflon supports. Neptunium was sorbed to a lesser extent. 8 refs., 6 figs., 6 tabs.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 60130
- Report Number(s):
- UCRL-94721; CONF-861207-111; ON: DE87012244
- Resource Relation:
- Conference: Materials Research Society (MRS) fall meeting, Boston, MA (United States), 1-5 Dec 1986; Other Information: PBD: Jan 1987
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
RADIOACTIVE WASTE DISPOSAL
SITE SELECTION
GLASS
LEACHING
CHEMICAL COMPOSITION
TUFF
RADIONUCLIDE MIGRATION
PERMEABILITY
WASTE FORMS
TECHNETIUM 99
NEPTUNIUM 237
URANIUM 238
PLUTONIUM 239
GROUND WATER
BORON
MOLYBDENUM
SODIUM
SILICON
STRONTIUM
HIGH-LEVEL RADIOACTIVE WASTES
YUCCA MOUNTAIN
NEVADA
BENCH-SCALE EXPERIMENTS
SIMULATION
LEACHATES
EXPERIMENTAL DATA
PH VALUE
TIME DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
Yucca Mountain Project