Investigation of Rock Thermal Properties for Nuclear Waste Disposal Using Advanced Hardware-Methodical Basis

• Published in: Rock mechanics and rock engineering Vol. 56; no. 6; pp. 4583 - 4612
• Main Authors: Popov, Y., Ostrizhniy, D., Chekhonin, E., Spasennykh, M., Romushkevich, R., Moiseenko, E., Bogatov, S., Kirik, S.
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.06.2023; Springer Nature B.V
• Subjects: Anisotropy; Capacity; Civil Engineering; Coefficients; Cores; Data acquisition; Data analysis; Data processing; Earth and Environmental Science; Earth Sciences; Geomechanics; Geophysics/Geodesy; Hardware; Heat; Heat conductivity; Heat transfer; Heterogeneity; Massifs; Mechanical properties; Modulus of elasticity; Original Paper; P waves; Profiling; Radioactive waste disposal; Radioactive wastes; Rock; Rocks; Sediment samples; Specific heat; Temperature; Thermal conductivity; Thermal expansion; Thermal properties; Thermodynamic properties; Velocity; Waste disposal; Wave velocity; Rock thermal properties; Advanced measuring techniques; Rock heterogeneity and anisotropy; Radioactive waste disposal
• ISSN: 0723-2632; 1434-453X
• DOI: 10.1007/s00603-023-03294-3

Results of experimental investigation of thermal properties (thermal conductivity, volumetric heat capacity, coefficient of linear thermal expansion, thermal anisotropy coefficients) of gneisses and dolerites (Krasnoyarsk region, Siberia, Russia) are described in the paper. The work is aimed at the data acquisition for safe deep geological disposal of radioactive waste. About 1500 measurements on more than 50 rock samples were performed totally. The experiments were performed using advanced hardware-methodical base that provided non-contact non-destructive high-precision measurements of thermal conductivity and volumetric heat capacity with continuous high-resolution profiling of these properties on full-size core samples, characterization of rock anisotropy and multi-scale heterogeneity. The numerous thermal profiling resulted in 3D images of thermal conductivity and volumetric heat capacity constructed on cylindrical surfaces of the core samples. Special approaches to experimental data processing were applied to improve representativeness of results. Temperature dependencies of rock thermal conductivity and volumetric heat capacity were characterized within a range of 5–200 °C. Differential and integral coefficients of linear thermal expansion were studied within this temperature range accounting to the rock anisotropy. Essential multi-scale heterogeneity, 2D (textural) anisotropy and microanisotropy of rocks were established and characterized. Significant differences in the thermal properties of gneisses and dolerites were demonstrated. Relationships between thermal conductivity and geomechanical characteristics (Young's modulus, P-wave velocity) of gneisses were specified for a more complete rock characterization. Recommendations for application of the developed advanced hardware-methodical base for experimental investigations of rock massifs for safe disposal of radioactive waste and other goals are given. Highlights The method of experimental investigations of multi-scale distribution of thermal properties of the rock massif was developed. Gneisses and dolerites differ significantly in thermal conductivity, volumetric heat capacity, degree of thermal anisotropy, and thermal expansion. Regularities in variations of rock thermal conductivity and volumetric heat capacity within a temperature range of 5–200 °C were characterized. Published dependences of thermal conductivity with Young's modulus and P-wave velocity in gneisses were refined. For the first time, the uncertainty in the results of measurements of thermal properties caused by rock heterogeneity and anisotropy was quantified.