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U.S. Department of Energy
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Numerical modeling of the Near Surface Test Facility No. 1 and No. 2 heater tests

Conference ·
OSTI ID:6137138

Thermomechanical predictive calculations have been undertaken for two full scale heater tests No. 1 and No. 2 at the Near Surface Test Facility (NSTF) at Hanford, Washington. Numerical predictions were made of the basaltic rock response involving temperatures, displacements, strains and stresses due to energizing the electrical heaters. The basalt rock mass was modeled as an isotropic thermal material but with temperature dependent thermal conductivity, specific heat and thermal expansion. The fractured nature of the basalt necessitated that it be modeled as a cross anisotropic medium with a bi-linear locking stress strain relationship. The cross-anisotropic idealization was selected after characterization studies indicated that a vertical columnar structure persisted throughout the test area and no major throughgoing discontinuities were present. The deformational properties were determined from fracture frequency and orientation, joint deformational data, Goodman Jack results and two rock mass classification schemes. Similar deformational moduli were determined from these techniques, except for the Goodman Jack results. The finite element technique was utilized for both the non-linear thermal and mechanical computations. An incremental stiffness method with residual force correction was employed to solve the non-linear problem by piecewise linearization. Two and three dimensional thermomechanical scoping calculations were made to assess the significance of various parameters and associated errors with geometrical idealizations. Both heater tests were modeled as two dimensional axisymmetric geometry with water assumed to be absent. Instrument response was predicted for all of the thermocouples, extensometers, USBM borehole deformation and IRAD gages for the entire duration of both tests.

Research Organization:
Rockwell International Corp., Richland, WA (USA). Rockwell Hanford Operations; Agapito (J.F.T.) and Associates, Grand Junction, CO (USA); Dames and Moore, Burlington, MA (USA)
DOE Contract Number:
AC06-77RL01030
OSTI ID:
6137138
Report Number(s):
RHO-BWI-SA-146; CONF-810624-9; ON: DE81026575
Country of Publication:
United States
Language:
English