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Title: Thermal properties measurements on rocksalt samples from the site of the proposed Waste Isolation Pilot Plant

Technical Report ·
DOI:https://doi.org/10.2172/5417159· OSTI ID:5417159

Thermal conductivity, thermal expansion, and specific heat measurements have been made on a number of specimens. The specific heat measurements were made by differential scanning calorimetry and the results showed that the specific heats of both clean rocksalt samples and of dirty samples with less than or equal to 7% insoluble impurities were essentially identical to the published specific heat for pure NaCl. In the thermal expansion measurements, two distinct groups of samples were identified. The first group had average expansion coefficients in the temperature range 300 to 700/sup 0/K close to that reported for pure NaCl. All the samples in this group were composed predominantly of halite, with only small amounts of other minerals or materials present. A second group of samples had expansion coefficients only approx. 0.3 to 0.5 that of NaCl. The samples in this group were composed largely of polyhalite, anhydrite, or siltstone. The measurements first reported by Acton on the thermal conductivity of samples taken from a borehole at the site of the proposed nuclear waste isolation pilot plant (WIPP) near Carlsbad, NM, have been extended to include additional samples and higher temperature measurements. This is not believed to be the result of the onset of radiative thermal transport because the deviations are negative as well as positive. Infrared transmission measurements on rocksalt samples from the proposed WIPP site show no transmission in the 3 to 10 ..mu..m wavelength range for samples > 5 cm thick. Use of the estimated infrared absorption coefficient leads to the conclusion that there is little radiative heat transport for T < 800/sup 0/K. All samples were dense with little or no porosity evident. On the basis of these experiments, it is concluded that the thermal conductivity of materials found at the site can be predicted to an accuracy +- 30% from knowledge of the composition and grain size of these materials.

Research Organization:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
AC04-76DP00789
OSTI ID:
5417159
Report Number(s):
SAND-80-0799; TRN: 80-011211
Country of Publication:
United States
Language:
English