Far-field thermomechanical response of argillaceous rock to emplacement of a nuclear-waste repository

Technical Report · Fri Aug 01 04:00:00 EDT 1980

OSTI ID:59408

McVey, D F; Thomas, R K; Lappin, A R

Before heat-producing wastes can be emplaced safely in any argillaceous rock, it will be necessary to understand the far-field thermal and thermomechanical response of this rock to waste emplacement. This report presents the results of a first series of calculations aimed at estimating the far-field response of argillite to waste emplacement. Because the thermal and mechanical properties of argillite are affected by its content of expandable clay, its behavior is briefly compared and contrasted with that of a shale having the same matrix thermal properties, but containing no expandable clay. Under this assumption, modeled temperatures are the same for the two rock types at equivalent power densities and reflect the large dependence of in-situ temperatures on both initial power density and waste type. Thermomechanical calculations indicate that inclusion of contraction behavior of expandable clays in the assumed argillite thermal expansion behavior results, in some cases, in generation of a large zone in and near the repository that has undergone volumetric contraction but is surrounded by uniformly compressive stresses. Information available to date indicates that this contraction would likely result in locally increased fluid permeability and decreased in-situ thermal conductivity, but might well be advantageous as regards radionuclide retention, because of the increased surface area within the contracted zone. Assumption of continuous and positive expansion behavior for the shale eliminates the near-repository contraction and tensional zones, but results in near-surface tensional zones directly above the repository.

• Research Organization: Sandia National Labs., Albuquerque, NM (United States)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 59408
• Report Number(s): SAND--79-2230
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES
ARGILLITE
CLAYS
EXPERIMENTAL DATA
ISOTHERMS
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTE FACILITIES
SHALES
STRAINS
STRESSES
TEMPERATURE EFFECTS
THEORETICAL DATA
THERMAL CONDUCTIVITY
THERMAL EXPANSION
THERMODYNAMIC PROPERTIES
THERMODYNAMICS
UNDERGROUND DISPOSAL
Yucca Mountain Project