Experimental studies of packing material stability

Conference · Tue Nov 01 04:00:00 EST 1983

OSTI ID:6860652

Allen, C C; Lane, D L; Palmer, R A; Johnston, R G

The Basalt Waste Isolation Project is conducting experiments to assess the stability of bentonite (sodium montmorillonite) and crushed basalt as waste package packing materials in a nuclear waste repository in basalt. The experiments are designed to identify changes in physical, chemical, and mineralogical properties that these materials could undergo in the repository environment. A series of bentonite dehydration experiments showed that after 1 year at 370/sup 0/C the clay's structural and swelling properties were preserved and only reversible dehydration occurred. At 440/sup 0/C, however, irreversible dehydration, collapse of the clay structure, and loss of swelling ability took place. Hydrothermal tests using bentonite, or an equal mixture of bentonite and basalt, along with synthetic groundwater, were also conducted. A bentonite + water experiment showed negligible structural alteration at 200/sup 0/C, although some iron enrichment of the clay occurred. At 300/sup 0/C, partial conversion of the montmorillonite to an iron- and potassium-rich smectite occurred, along with the formation of secondary quartz and albite. An experiment in the basalt + bentonite + water system at 150/sup 0/C resulted in partial etching of the basalt grains, but no detectable change in rock or clay mineralogy. At 300/sup 0/C, the basalt was strongly etched. Furthermore, iron- and potassium-rich smectite apparently replaced montmorillonite as the dominant clay, and secondary silica, zeolites, and minor feldspar were formed. These mineral assemblages are thought to be metastable at 300/sup 0/C, based on natural analogs. The kinetics and reaction paths of further transformations of packing materials are important areas for continued study. 10 references, 5 figures, 1 table.

• Research Organization: Rockwell International Corp., Richland, WA (USA). Rockwell Hanford Operations
• DOE Contract Number: AC06-77RL01030
• OSTI ID: 6860652
• Report Number(s): RHO-BW-SA-313/P; CONF-8311124-5; ON: DE84014699
• Country of Publication: United States
• Language: English

Related Subjects

052002* -- Nuclear Fuels-- Waste Disposal & Storage
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
36 MATERIALS SCIENCE
360603 -- Materials-- Properties
BACKFILLING
BASALT
BENTONITE
CHEMICAL PROPERTIES
CLAYS
DATA
EXPERIMENTAL DATA
HIGH-LEVEL RADIOACTIVE WASTES
IGNEOUS ROCKS
INFORMATION
MANAGEMENT
MATERIALS
MINERALOGY
NUMERICAL DATA
PHYSICAL PROPERTIES
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTES
ROCK-FLUID INTERACTIONS
ROCKS
STABILITY
VOLCANIC ROCKS
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES