Geochemical behavior of supercalcine waste form: its stability in a basalt environment

Technical Report · Mon Jun 01 04:00:00 EDT 1981

OSTI ID:5196572

Holloway, J R; Jenkins, D M; Kacoyannakis, J F; Apted, M J

This report presents the initial results of the quantitative phase of the hydrothermal testing program on the geochemical behavior of waste forms. Two investigations involving supercalcine have been performed and the results are recorded in this report. One experiment involves the interaction of supercalcine with groundwater while the second involves the interaction of a mixture of supercalcine plus basalt with groundwater. Both experiments have been carried out under the maximum conditions anticipated in the repository, namely 300/sup 0/C and 300 bars (30 MPa). Many unanswered questions remain, concerning the speciation of cations in solution, the full characterization of phases formed, and the prevailing Eh-pH conditions of reacted groundwater. Preliminary data have been obtained on the cations that were readily leached from unsintered supercalcine (SPC-4) and the general solubility properties of the groundwater buffered by SPC-4 +- basalt. In particular, it is observed that Si, Na, Mo, Rb, and Cr are readily leached from SPC-4 in the absence of basalt, and all of these except Cr are leached in the presence of basalt. Groundwater buffered by SPC-4 alone is thought to have in situ pH and Eh conditions of approx. 9.5 +- 0.5 and 0.0 to -0.4 V, respectively. Four secondary phases have been identified with some degree of certainty: pollucite ((Cs,Na)AlSi/sub 2/O/sub 6/.xH/sub 2/O), ulvospinel (Fe/sub 2/TiO/sub 4/), ..cap alpha..-RuCl/sub 3/, and (Sr,Ca)MoO/sub 4/. Phases have not been identified to house the insoluble elements Zr, U, P, or Ba as well as the elements whose concentrations <0.2 wt % of the oxide. Finally, it is pointed out that further attention must be directed to the elements that have radionuclides of high biological danger, even if they do not seem dangerous from the aspect of their low thermal output.

• Research Organization: Rockwell International Corp., Richland, WA (USA). Rockwell Hanford Operations
• DOE Contract Number: AC06-77RL01030
• OSTI ID: 5196572
• Report Number(s): RHO-BWI-C-105; ON: DE82006849
• Country of Publication: United States
• Language: English

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11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
ALKALI METALS
BASALT
BENCH-SCALE EXPERIMENTS
CALCINED WASTES
CHROMIUM
CRYSTAL STRUCTURE
DATA
DISSOLUTION
ELECTRON MICROSCOPY
ELEMENTS
ENVIRONMENTAL TRANSPORT
EXPERIMENTAL DATA
GEOLOGIC DEPOSITS
GROUND WATER
HIGH PRESSURE
HIGH TEMPERATURE
HIGH-LEVEL RADIOACTIVE WASTES
HYDROGEN COMPOUNDS
IGNEOUS ROCKS
INFORMATION
LEACHING
MANAGEMENT
MASS TRANSFER
MATERIALS
METALS
MICROSCOPY
MICROSTRUCTURE
MOLYBDENUM
NUMERICAL DATA
OXYGEN COMPOUNDS
PH VALUE
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTES
RADIONUCLIDE MIGRATION
ROCKS
RUBIDIUM
SCANNING ELECTRON MICROSCOPY
SEMIMETALS
SEPARATION PROCESSES
SILICON
SODIUM
TIME DEPENDENCE
TRANSITION ELEMENTS
UNDERGROUND DISPOSAL
VOLCANIC ROCKS
WASTE DISPOSAL
WASTE MANAGEMENT
WASTE-ROCK INTERACTIONS
WASTES
WATER