Calculated thermally induced displacements and stresses for heater experiments at Stripa, Sweden. Linear thermoelastic models using constant material properties
Thermally induced displacements and stresses have been calculated by finite element analysis to guide the design, operation, and data interpretation of the in situ heating experiments in a granite formation at Stripa, Sweden. There are two full-scale tests with electrical heater canisters comparable in size and power to those envisaged for reprocessed high level waste canisters and a time-scaled test. To provide a simple theoretical basis for data analysis, linear thermoelasticity was assumed. Constant (temperature-independent) thermal and mechanical rock properties were used in the calculations. These properties were determined by conventional laboratory testing on small intact core specimens recovered from the Stripa test site. Two-dimensional axisymmetric models were used for the full-scale experiments, and three-dimensional models for the time-scaled experiment. Highest compressive axial and tangential stresses are expected at the wall of the heater borehole. For the 3.6 kW full-scale heated experiment, maximum compressive tangential stress was predicted to be below the unconfined compressive strength of Stripa granite, while for the 5 kW experiment, the maximum was approximately equal to the compressive strength before the concentric ring of eight 1 kW peripheral heaters was activated, but would exceed that soon afterwards. Three zones of tensile thermomechanical stresses will occur in each full-scale experiment. Maximum vertical displacements range from a fraction of a millimeter over most of the instrumented area of the time-scaled experiment to a few millimeters in the higher-power full-scale experiment. Radial displacements are typically half or less than vertical displacements. The predicted thermomechanical displacements and stresses have been stored in an on-site computer to facilitate instant graphic comparison with field data as the latter are collected.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); California Univ., Berkeley (USA). Dept. of Materials Science and Mineral Engineering
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5325687
- Report Number(s):
- LBL-7061; SAC-22; TRN: 80-011196
- Country of Publication:
- United States
- Language:
- English
Similar Records
Thermomechanical modeling and data analysis for heating experiments at Stripa, Sweden
Theoretical temperature fields for the Stripa heater project. Vol. 1
Related Subjects
58 GEOSCIENCES
GRANITES
TEMPERATURE EFFECTS
THERMOELASTICITY
MATHEMATICAL MODELS
BENCH-SCALE EXPERIMENTS
COMPRESSION STRENGTH
DISPLACEMENT RATES
EXPERIMENTAL DATA
FIELD TESTS
FINITE ELEMENT METHOD
HEAT TREATMENTS
MECHANICAL PROPERTIES
MINES
RADIOACTIVE WASTE DISPOSAL
ROCK MECHANICS
STRESSES
SWEDEN
THERMODYNAMIC PROPERTIES
THREE-DIMENSIONAL CALCULATIONS
TWO-DIMENSIONAL CALCULATIONS
UNDERGROUND DISPOSAL
DATA
ELASTICITY
EUROPE
IGNEOUS ROCKS
INFORMATION
MANAGEMENT
NUMERICAL DATA
NUMERICAL SOLUTION
PHYSICAL PROPERTIES
PLUTONIC ROCKS
ROCKS
SCANDINAVIA
TENSILE PROPERTIES
TESTING
WASTE DISPOSAL
WASTE MANAGEMENT
WESTERN EUROPE
052002* - Nuclear Fuels- Waste Disposal & Storage
580300 - Mineralogy
Petrology
& Rock Mechanics- (-1989)