Water migration through compacted bentonite backfills for containment of high-level nuclear waste

Journal Article · Sat Jan 01 00:00:00 EST 1983 · Nucl. Chem. Waste Manage.; (United States)

DOI:https://doi.org/10.1016/0191-815X(83)90054-2· OSTI ID:6249954

Westsik, J H; Hodges, F N; Kuhn, W L; Myers, T R

Tests carried out with compacted sodium and calcium bentonites at room temperature indicate that bentonite backfills will effectively control water movement near a high-level nuclear waste package. Saturation tests indicate that water will rapidly diffuse into a dry bentonite backfill, reaching saturation in times on the order of tens of years. The apparent diffusion coefficient for sodium bentonite (about5 wt% initial water content) compacted to 2.1 g/cm/sup 3/ is 1.7 x 10/sup -6/ cm/sup 2//sec. However, the hydraulic conductivities of saturated bentonites are low, ranging from approximately 10/sup -11/ cm/sec to 10/sup -13/ cm/sec over a density range of 1.5 g/cm/sup 3/ to 2.2 g/cm/sup 3/. The hydraulic conductivities of compacted bentonites are at least several orders of magnitude lower than those of candidate-host silicate rocks, indicating that most flowing groundwater contacting a bentonite backfill would be diverted around the backfill rather than flowing through it. In addition, because of the very low hydraulic conductivities of bentonite backfills, the rate of chemical transport between the containerized waste and the surrounding host rock will be effectively controlled by diffusion through the backfill. The formation of a diffusion barrier by the backfill will significantly reduce the long-term rate of radionuclide release from the waste package, an advantage distinct from the delay in release resulting from the sorptive properties of a bentonite backfill.

• Research Organization: Pacific Northwest Laboratory, Richland, Washington
• OSTI ID: 6249954
• Journal Information: Nucl. Chem. Waste Manage.; (United States), Vol. 4:4
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
54 ENVIRONMENTAL SCIENCES
BENTONITE
HYDRAULIC CONDUCTIVITY
SORPTIVE PROPERTIES
GROUND WATER
DIFFUSION
HIGH-LEVEL RADIOACTIVE WASTES
RADIOACTIVE WASTE DISPOSAL
UNDERGROUND DISPOSAL
BACKFILLING
CALCIUM COMPOUNDS
COMPACTS
MATERIALS TESTING
RADIONUCLIDE MIGRATION
ROCK-FLUID INTERACTIONS
SILICATES
SODIUM COMPOUNDS
WATER SATURATION
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
CLAYS
ENVIRONMENTAL TRANSPORT
HYDROGEN COMPOUNDS
MANAGEMENT
MASS TRANSFER
MATERIALS
OXYGEN COMPOUNDS
RADIOACTIVE MATERIALS
RADIOACTIVE WASTES
SATURATION
SILICON COMPOUNDS
SURFACE PROPERTIES
TESTING
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES
WATER
052002* - Nuclear Fuels- Waste Disposal & Storage
510301 - Environment
Terrestrial- Radioactive Materials Monitoring & Transport- Soil- (-1987)
520301 - Environment
Aquatic- Radioactive Materials Monitoring & Transport- Water- (1987)