Assessment of potential radionuclide transport in site-specific geologic formations
Associated with the development of deep, geologic repositories for nuclear waste isolation is a need for safety assessments of the potential for nuclide migration. Frequently used in estimating migration rates is a parameter generally known as a distribution coefficient, K/sub d/, which describes the distribution of a radionuclide between a solid (rock) and a liquid (groundwater) phase. This report is intended to emphasize that the use of K/sub d/ must be coupled with a knowledge of the geology and release scenarios applicable to a repository. Selected K/sub d/ values involving rock samples from groundwater/brine simulants typical of two potential repository sites, WIPP and NTS, are used to illustrate this concern. Experimental parameters used in K/sub d/ measurements including nuclide concentration, site sampling/rock composition, and liquid-to-solid ratios are discussed. The solubility of U(VI) in WIPP brine/groundwater was addressed in order to assess the potential contribution of this phenomena to K/sub d/ values. Understanding mehanisms of sorption of radionuclides on rocks would lead to a better predictive capability. Sorption is attributed to the presence of trace constituents (often unidentified) in rocks. An attempt was made to determine if this applied to WIPP dolomite rocks by comparing sorption behavior of the natural material with that of a synthetic dolomite prepared in the laboratory with reagent grade chemicals. The results were inconclusive. The results of a study of Tc sorption by an argillite sample from the Calico Hills formation at NTS under ambient laboratory conditions were more conclusive. The Tc sorption was found to be associated with elemental carbon. Available evidence points to a reduction mechanism leading to the apparent sorption of Tc on the solid phase.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- DOE Contract Number:
- AC04-76DP000789
- OSTI ID:
- 5086730
- Report Number(s):
- SAND-79-2468; TRN: 80-017736
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
ARGILLITE
ROCK-FLUID INTERACTIONS
SORPTIVE PROPERTIES
DOLOMITE
SOLUBILITY
RADIOACTIVE WASTE DISPOSAL
UNDERGROUND DISPOSAL
TECHNETIUM
SORPTION
BRINES
ENVIRONMENTAL TRANSPORT
GROUND WATER
NEVADA TEST SITE
NEW MEXICO
PH VALUE
PILOT PLANTS
RADIONUCLIDE MIGRATION
RISK ASSESSMENT
SALT DEPOSITS
ALKALINE EARTH METAL COMPOUNDS
CARBON COMPOUNDS
CARBONATE ROCKS
CARBONATES
ELEMENTS
FUNCTIONAL MODELS
GEOLOGIC DEPOSITS
HYDROGEN COMPOUNDS
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MANAGEMENT
MASS TRANSFER
METALS
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
REFRACTORY METALS
ROCKS
SEDIMENTARY ROCKS
SHALES
SOUTHWEST REGION
SURFACE PROPERTIES
TRANSITION ELEMENTS
USA
WASTE DISPOSAL
WASTE MANAGEMENT
WATER
052002* - Nuclear Fuels- Waste Disposal & Storage
520301 - Environment
Aquatic- Radioactive Materials Monitoring & Transport- Water- (1987)
510301 - Environment
Terrestrial- Radioactive Materials Monitoring & Transport- Soil- (-1987)