Experimental investigation of sodium bentonite stability in Hanford basalt
Sodium bentonite is a candidate material for the waste package backfill component in a repository in basalt at the Hanford Site. Preliminary hydrothermal experiments have been conducted under near-field geochemical conditions expected to occur in the reference repository location in Grande Ronde Basalt. Experiments have been conducted in the basalt/groundwater, bentonite/groundwater, and basalt/bentonite/groundwater systems. The experiments have been conducted at 300/sup 0/C using a simulated Grande Ronde groundwater, reference Umtanum basalt, and sodium bentonite. Key data generated by the experiments include experimental solution analyses as a function of time and preliminary solids analysis by scanning transmission electron microscopy and x-ray diffraction. Solution trends of the major aqueous species were similar in the three systems and are characterized by: (1) the gradual reduction of the pH value from approx.9.75 to a steady-state value of approx.6, (2) an initial rapid increase followed by a gradual decreasein silica concentration, and (3) a slight or negligible increase in sodium, sulfate, and chloride concentrations. In the bentonite/groundwater experiment, small amounts (<1%) of an albite reaction product were observed. Conserversely, the formation of illite, a common bentonite alteration product, was not observed. These results indicate tjhat sodium bentonite will remain sufficiently stablee at 300/sup 0/C under hydrothermal conditions in basalt to permit its use as a backfill material.
- Research Organization:
- Rockwell International Corp., Richland, WA (USA). Rockwell Hanford Operations
- DOE Contract Number:
- AC06-77RL01030
- OSTI ID:
- 6494312
- Report Number(s):
- RHO-BW-SA-219-P; CONF-821107-52; ON: DE83008328
- Resource Relation:
- Conference: 6. international symposium on the scientific basis for radioactive waste management, Boston, MA, USA, 1 Nov 1982
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
BACKFILLING
MATERIALS TESTING
BASALT
BENTONITE
STABILITY
GEOLOGIC DEPOSITS
GROUND WATER
HIGH-LEVEL RADIOACTIVE WASTES
LEACHING
RADIOACTIVE WASTE DISPOSAL
ROCK-FLUID INTERACTIONS
SODIUM COMPOUNDS
ALKALI METAL COMPOUNDS
CLAYS
DISSOLUTION
HYDROGEN COMPOUNDS
IGNEOUS ROCKS
MANAGEMENT
MATERIALS
OXYGEN COMPOUNDS
RADIOACTIVE MATERIALS
RADIOACTIVE WASTES
ROCKS
SEPARATION PROCESSES
TESTING
VOLCANIC ROCKS
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES
WATER
052002* - Nuclear Fuels- Waste Disposal & Storage
360603 - Materials- Properties