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U.S. Department of Energy
Office of Scientific and Technical Information

Microcharacterization of basalt: Considerations for a nuclear waste repository

Conference ·
OSTI ID:5083116

The National Waste Terminal Storage Program of the US Department of Energy is assessing a number of rock types to determine their suitability for the disposal of nuclear wastes. As a part of this effort, the Basalt Waste Isolation Project (BWIP) is investigating the Pasco Basin in southeastern Washington State as the possible site of a nuclear waste repository in basalt (NWRB). The microcharacterization work described in this paper results in a detailed identification of the minerals and other phase assemblages that provide the basis for a determination of the environment that acts to control geochemical conditions in an NWRB. Interactions between the basalt, groundwater, and proposed waste packages are being studied to ensure that the final repository and waste package designs meet all requirements for safety and isolation. The rock at the proposed repository location is a fine-grained tholeiite, containing crystals of plagioclase, pyroxene, and titaniferous magnetite plus a glass-rich mesostasis. Partial reaction of this mesostasis with groundwater is thought to be the predominant source of most elements in the groundwater. The composition of the mesostasis and its reaction thus should affect the chemical environment of the waste packages. For this reason, microcharacterization of the mesostasis, particularly the glass phase, has been conducted by the BWIP in support of hydrothermal laboratory studies that provide data to geochemical and performance models. 5 refs., 3 figs., 1 tab.

Research Organization:
Rockwell International Corp., Richland, WA (USA). Rockwell Hanford Operations
Sponsoring Organization:
DOE/RW
DOE Contract Number:
AC06-77RL01030
OSTI ID:
5083116
Report Number(s):
RHO-BW-SA-294; CONF-830871--9; ON: TI90006861
Country of Publication:
United States
Language:
English