Thermal conductivity of bentonite/quartz high-level-waste-package backfill

Technical Report · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6812938

Moss, M; Molecke, M A

A mixture of bentonite clay and quartz sand is being considered for use as a waste-package backfill, the material placed between a radioactive-waste canister and the repository host rock. Compacts of bentonite/quartz with weight-percent ratios of 100/0, 70/30, 50/50 and 30/70 were made at room temperature under a pressure of 100 MPa (15 ksi). Upon initial heating, the thermal conductivity of the 70/30 compact rose from 1.20 W/m.K at 298/sup 0/K to 1.32 W/m.K at 373/sup 0/K. After further heating to 473/sup 0/K, it fell to 1.10 W/m.K, reflecting the loss of interlamellar water from the bentonite. The conductivity of the now-dehydrated compact was reproducible through several heating and cooling cycles, varying from 1.15 W/m.K at 573/sup 0/K to 1.03 W/m.K at 298/sup 0/K. The other mixtures were qualitatively similar to the 70/30: the 100/0, 50/50 and 30/70 dehydrated compacts displayed conductivities of 0.59, 1.06 and 0.83 W/m.K, respectively, at 298/sup 0/K. Measured densities ranged from 1.98 to 2.12 g/cc. Combined geometric-mean and Maxwell models for thermal conduction in composite systems predict the measured results reasonably well. An analysis of the impact of backfills on high-level waste (HLW) package design indicates that no significant thermal penalty is imposed. 4 figures.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6812938
• Report Number(s): SAND-82-1274C; CONF-821107-4; ON: DE82022160
• Country of Publication: United States
• Language: English

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BACKFILLING
BENTONITE
CHALCOGENIDES
CLAYS
COMPACTS
DATA
DENSITY
EXPERIMENTAL DATA
INFORMATION
MANAGEMENT
MINERALS
NUMERICAL DATA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PACKAGING
PHYSICAL PROPERTIES
QUARTZ
RADIOACTIVE WASTE STORAGE
SILICON COMPOUNDS
SILICON OXIDES
STORAGE
THERMAL ANALYSIS
THERMAL CONDUCTIVITY
THERMODYNAMIC PROPERTIES
WASTE MANAGEMENT
WASTE STORAGE