Hostname: page-component-78c5997874-94fs2 Total loading time: 0 Render date: 2024-11-20T02:28:06.621Z Has data issue: false hasContentIssue false
  • English
  • Français

Leaching of Actinide-Doped Nuclear Waste Glass in a Tuff-Dominated System

Published online by Cambridge University Press:  28 February 2011

Fernando Bazan ,
J. Rego  and
R. D. Aines
Fernando Bazan
Affiliation:
Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94550
J. Rego
Affiliation:
Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94550
R. D. Aines
Affiliation:
Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94550
Get access

Abstract

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- 9actinide glass, which is a PNL 76-68 based glass doped with low levels of 99Tc, 237Np, 238U and 239Pu to simulate wastes. Disc samples of this glass were leached at 90°C for 30, 90, and 183 days inside tuff vessels using a natural groundwater (J-13 well-water) as the leachant. Some samples were held by 304L stainless steel supports to evaluate the effect of this metal on the release rate of glass constituents. At the end of each leaching interval, the J-13 water present inside and outside the rock vessel was analyzed for glass components in solution.

On the basis of these analyses, boron, molybdenum, and technetium appear to migrate through the rock at rates that depend on the porosity of each vessel and the time of reaction. The actinide elements (uranium, neptunium, and plutonium) were found only in the inner leachate. Sodium, silicon, and strontium are present in the rock as well as in the J-13 water, and the addition of these elements from the glass could not be determined. Normalized elemental mass loss values for boron, molybdenum, and technetium were calculated using the combined concentrations of the inner and outer leachates and assuming a negligible retention on the rock. The maximum normalized release was 2.3 g/m 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 5-10% 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. Future analysis of the tuff vessels will determine whether the actinides were strongly sorbed on the surface of the tuff rock.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 84: Symposium L – Scientific Basis for Nuclear Waste Management X , 1986 , 447
Copyright
Copyright © Materials Research Society 1987

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

[1] Oversby, V. M., The Nevada Nuclear Waste Storage Investigations Project Waste Form Testing Program, Lawrence Livermore National Laboratory, Livermore, CA, UCRL-89477, November 1983.Google Scholar
[2] Bazan, F. and Rego, J., Parametric Testing of a DWPF Glass, Lawrence Livermore National Laboratory, Livermore, CA, UCRL-53606, March 1985.Google Scholar
[3] Bibler, N. E., Wicks, G. G., and Oversby, V. M., Leaching Savannah River Plant Nuclear Waste Glass in a Saturated Tuff Environment, Lawrence Livermore National Laboratory, Livermore, CA, UCRL Preprint-91258, November 1984, in Materials Research Society Symposium Proceedings, 44, C. M. Jantzen et al., eds., pp. 247-256, 1985.Google Scholar
[4] Wald, J. W., Fabrication and Characterization of MCC Approved Testing Material - ATM-8 Glass, Pacific Northwest Laboratory, Richland, WA, PNL-5577-8 UC-70, October 1985.Google Scholar
[5] Oversby, V. M., Reaction of the Topopah Spring Tuff with J-13 Well Water at 90 °C and 150 °C, Lawrence Livermore National Laboratory, Livermore, CA, UCRL-53552, May 1984.Google Scholar
[6] Mendel, J. E., Final Report of the Defense High-Level Waste Leaching Mechanisms Program, Pacific Northwest Laboratory, Richland, WA, PNL-5157, August 1984.Google Scholar
[7] McVay, G. L. and Robinson, G. R., Effects of Tuff Waste Package Components on Release From 76-68 Simulated Waste Glass, Pacific Northwest Laboratory, Richland, WA, PNL-4897, April 1984.Google Scholar
[8] Bazan, F. and Rego, J. H., The Tuff Reaction Vessel Experiment. Lawrence Livermore National Laboratory, Livermore, CA, UCRL 53735, June 1986.Google Scholar