Thermal diffusion processes in aqueous sodium chloride solutions
- Sandia National Labs., Albuquerque, NM (United States)
- ManTech Environmental Technology, Inc., Corvallis, OR (United States)
The experimental results for the Soret coefficients are variable, but suggest a trend with NaCl concentration that is consistent with electrolyte solution behavior. The temperature dependence of the Soret coefficients is in approximate agreement with previous measurements obtained using other techniques. In general, the Soret coefficient values are best interpreted based on the expansion of the fluid inclusion migration fields. The high temperature values for {sigma} at 1.0 N NaCl concentration suggest an expansion of the migration field to smaller inclusion sizes, which for a single halite crystal at these conditions, approach a dimension of one micron. The corresponding fluid inclusion size for the polycrystalline material, where grain boundaries retard the migration, is approximately 10 microns. Although the Soret results obtained in the present study provide additional data for high temperature applications in nuclear waste isolation, more experimentation and new equipment design are required in order to obtain data at temperatures above 80{degree}C. The experimental approach utilized in this study is limited in that respect. The almost immeasurable nature of the thermal diffusion process for the brines as examined in the laboratory, suggests that this effect will be insignificant (outside of fluid inclusion migration) in most rock-water interactions associated with a rocksalt nuclear waste repository. Other effects, such as convective fluid transport, pressure solution, and groundwater flow, will be orders-of-magnitude more important in evaluating the critical nature of brine migration, waste canister corrosion, and the potential for leaching radioisotopes from waste repositories.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 10183844
- Report Number(s):
- SAND-92-1275; ON: DE93002596
- Resource Relation:
- Other Information: PBD: 18 Aug 1992
- Country of Publication:
- United States
- Language:
- English
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