Natural-analog studies for partial validation of conceptual models of radionuclide retardation at the Waste Isolation Pilot Plant (WIPP)
- New Mexico Univ., Albuquerque, NM (USA). Dept. of Geology
- Sandia National Labs., Albuquerque, NM (USA)
Transport by groundwater within the Culebra Dolomite, an aquifer above the Waste Isolation Pilot Plant (WIPP), is the most probable mechanism for long-term release of radionuclides to the accessible environment. Radionuclides could be retarded by sorption if the groundwater is exposed to sufficient amounts of fracture-lining clays. In this natural-analog study, distributions of U and trace metals have been examined to constrain the strength of clay/solute interactions within the Culebra. Uranium solid/liquid distribution ratios, calculated from U concentrations of groundwaters and consanguineous fracture-filling clays, range from {approximately}80 to 800 m{ell}/g and imply retardation factors of 60 to 500 using a fracture-flow model. Retardation factors inferred from uranium-series disequilibria and {sup 14}C ages in Culebra groundwaters alone are much lower ({approximately}10), implying that clays may contain a significant unreactive component of U. Such a possibility is corroborated by Rb/Sr ages; these imply long-term stability of the clays,with resetting occurring more than 250 Ma ago. Factor analysis and mass-balance calculations suggest, however, that Mg-rich clays are dissolving in Pleistocene-age groundwaters and/or are converting to Na-rich smectites, and that B and Li are taken up from the water by the clays. Apparently, the solution chemistry reflects gradual equilibration of clays with groundwater, but thus far the bulk of the clays remain structurally intact. Measurements of the distribution of U in the Culebra will be more meaningful if the inert and exchangeable components of the U content of the clays can be quantified. 26 refs., 3 figs., 2 tabs.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- Sponsoring Organization:
- DOE/DP
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 6534976
- Report Number(s):
- SAND-90-1275C; CONF-9011116--1; ON: DE91001339
- Country of Publication:
- United States
- Language:
- English
Similar Records
Studies of radionuclide sorption by clays in the Culebra Dolomite at the Waste Isolation Pilot Plant site, southeastern New Mexico
Hydrogeochemical studies of the Rustler Formation and related rocks in the Waste Isolation Pilot Plant Area, Southeastern New Mexico
Related Subjects
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
54 ENVIRONMENTAL SCIENCES
540330 -- Environment
Aquatic-- Radioactive Materials Monitoring & Transport-- (1990-)
ACTINIDES
ALKALINE EARTH METAL COMPOUNDS
AQUIFERS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CLAYS
DOLOMITE
ELEMENTS
ENVIRONMENTAL TRANSPORT
FUNCTIONAL MODELS
GROUND WATER
HYDROGEN COMPOUNDS
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MASS TRANSFER
METALS
MINERALOGY
MINERALS
NATIONAL ORGANIZATIONS
NUCLEAR FACILITIES
OXYGEN COMPOUNDS
PILOT PLANTS
RADIOACTIVE WASTE FACILITIES
RADIONUCLIDE MIGRATION
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
UNDERGROUND FACILITIES
URANIUM
US DOE
US ORGANIZATIONS
WATER
WIPP