Radionuclide Transport Models Under Ambient Conditions
The purpose of this Analysis/Model Report (AMR) is to evaluate (by means of 2-D semianalytical and 3-D numerical models) the transport of radioactive solutes and colloids in the unsaturated zone (UZ) under ambient conditions from the potential repository horizon to the water table at Yucca Mountain (YM), Nevada. This is in accordance with the ''AMR Development Plan U0060, Radionuclide Transport Models Under Ambient Conditions'' (CRWMS M and O 1999a). This AMR supports the UZ Flow and Transport Process Model Report (PMR). This AMR documents the UZ Radionuclide Transport Model (RTM). This model considers: the transport of radionuclides through fractured tuffs; the effects of changes in the intensity and configuration of fracturing from hydrogeologic unit to unit; colloid transport; physical and retardation processes and the effects of perched water. In this AMR they document the capabilities of the UZ RTM, which can describe flow (saturated and/or unsaturated) and transport, and accounts for (a) advection, (b) molecular diffusion, (c) hydrodynamic dispersion (with full 3-D tensorial representation), (d) kinetic or equilibrium physical and/or chemical sorption (linear, Langmuir, Freundlich or combined), (e) first-order linear chemical reaction, (f) radioactive decay and tracking of daughters, (g) colloid filtration (equilibrium, kinetic or combined), and (h) colloid-assisted solute transport. Simulations of transport of radioactive solutes and colloids (incorporating the processes described above) from the repository horizon to the water table are performed to support model development and support studies for Performance Assessment (PA). The input files for these simulations include transport parameters obtained from other AMRs (i.e., CRWMS M and O 1999d, e, f, g, h; 2000a, b, c, d). When not available, the parameter values used are obtained from the literature. The results of the simulations are used to evaluate the transport of radioactive solutes and colloids, and to determine the processes, mechanisms, and geologic features that have a significant effect on it. They evaluate the contributions of daughter products of radioactive decay to transport from the bottom of the potential repository to the water table. The effect of the various conceptual models of perched water bodies on transport is also evaluated. Note that a more thorough study of perched water bodies can be found in another AMR (CRWMS M and O 1999d, Sections 6.2 and 6.6). The primary caveat for using the modeling results documented here is that the input transport parameters were based on limited site data. For some input parameters, best estimates were used because no specific data were available. An additional caveat is that the RTM is based on the conceptual models and numerical approaches used for developing the flow fields and infiltration maps, and thus they share the same limitations.
- Research Organization:
- Yucca Mountain Project, Las Vegas, NV (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- OSTI ID:
- 837084
- Report Number(s):
- MDL-NBS-HS-000008, REV 00; MOL.19990721.0529, DC 23356; TRN: US0502313
- Resource Relation:
- Other Information: PBD: 12 Mar 2000
- Country of Publication:
- United States
- Language:
- English
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