Comparison of the hydrothermal stability of simulated spent fuel and borosilicate glass in a basaltic environment
Simulated spent fuel and borosilicate glass (PNL 76-68) were hydrothermally reacted with Umtanum basalt under test conditions simulating expected conditions for a nuclear waste repository located in basalt (NWRB) at the Hanford Site, Washington. Tests were performed in gold-bag sampling autoclaves at temperatures between 100/sup 0/C and 300/sup 0/C, 300 bars pressure, and a variety of mass ratios for the solids and groundwater. Systematic solution analyses included monitoring of pH, Eh, and dissolved concentrations of both matrix elements and potential radionuclides (as stable analog elements). All dissolved species displayed either steady-state concentration limits or decreasing concentration behavior after the first several hundred hours. Solids characterization suggests that formation of secondary alteration solids, such as alkali feldspar, smectite clays, scapolite, and a variety of uranium-rich silicate phases, impose solubility limits to the release of many potential radioactive elements. These steady-state (or solubility) concentration limits can be coupled with measured hydrologic flow rates to calculate meaningful radionuclide release rates from the waste form for a NWRB. It should be noted that comparison of waste forms from hydrothermal test results is limited by the chemical and structural disparity of the waste forms. Because of this disparity, each waste form will buffer the reacting system at different environmental conditions (e.g., pH, Eh) and, thus, the secondary solids that control radionuclide concentration levels will be necessarily different for each system. Emphasis on the stability of precipitated radionuclide-bearing solids (fate of radionuclides) is the preferred method of performance assessment.
- Research Organization:
- Rockwell International Corp., Richland, WA (USA). Rockwell Hanford Operations
- DOE Contract Number:
- AC06-77RL01030
- OSTI ID:
- 6467962
- Report Number(s):
- RHO-BW-ST-38-P; ON: DE83010203
- Country of Publication:
- United States
- Language:
- English
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Hydrothermal reaction of simulated waste forms with barrier materials under conditions expected in a nuclear waste repository in basalt
Comparison of the hydrothermal stability of simulated spent fuel and borosilicate glass in a basaltic environment
Related Subjects
BASALT
WASTE-ROCK INTERACTIONS
BOROSILICATE GLASS
SPENT FUELS
EXPERIMENTAL DATA
HANFORD RESERVATION
HYDROTHERMAL ALTERATION
SOLUBILITY
WASHINGTON
DATA
ENERGY SOURCES
FEDERAL REGION X
FUELS
GLASS
IGNEOUS ROCKS
INFORMATION
MATERIALS
NATIONAL ORGANIZATIONS
NORTH AMERICA
NUCLEAR FUELS
NUMERICAL DATA
REACTOR MATERIALS
ROCKS
US DOE
US ERDA
US ORGANIZATIONS
USA
VOLCANIC ROCKS
052002* - Nuclear Fuels- Waste Disposal & Storage