A modeling study of contaminant transport resulting from flooding of Pit 9 at the Radioactive Waste Management Complex, Idaho National Engineering Laboratory
A simulation study was conducted to determine if dissolved-phase transport due to flooding is a viable mechanism for explaining the presence of radionuclides in sedimentary interbeds below the Radioactive Waste Management Complex. In particular, the study focused on {sup 241}Am migration due to flooding of Pit 9 in 1969. A kinetically-controlled source term model was used to estimate the mass of {sup 241}Am that leached as a function of a variable surface infiltration rate. This mass release rate was then used in a numerical simulation of unsaturated flow and transport to estimate the advance due to flooding of the {sup 241}Am front down towards the 110 ft interbed. The simulation included the effect of fractures by superimposing them onto elements that represented the basalt matrix. For the base case, hydraulic and transport parameters were assigned using the best available data. The advance of the {sup 241}Am front due to flooding for this case was minimal, on the order of a few meters. This was due to the strong tendency for {sup 241}Am to sorb onto both basalts and sediments. In addition to the base case simulation, a parametric sensitivity study was conducted which tested the effect of sorption in the fractures, in the kinetic source term, and in the basalt matrix. Of these, the only case which resulted in significant transport was when there was no sorption in the basalt matrix. The indication being that other processes such as transport by radiocolloids or organic complexation may have contributed. However, caution is advised in interpreting these results due to approximations in the numerical method that was used incorporate fractures into the simulation. The approximations are a result of fracture apertures being significantly smaller than the elements over which they are superimposed. The sensitivity of the {sup 241}Am advance to the assumed hydraulic conductivity for the fractures was also tested.
- Research Organization:
- EG and G Idaho, Inc., Idaho Falls, ID (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC07-76ID01570
- OSTI ID:
- 10167003
- Report Number(s):
- EGG-EEL-10498; ON: DE93016668; TRN: 93:015538
- Resource Relation:
- Other Information: PBD: Sep 1992
- Country of Publication:
- United States
- Language:
- English
Similar Records
RADIONUCLIDE TRANSPORT IN FRACTURED TUFF UNDER EPISODIC FLOW CONDITIONS
Modeling Single Well Injection-Withdrawal (SWIW) Tests for Characterization of Complex Fracture-Matrix Systems
Related Subjects
RADIONUCLIDE MIGRATION
SIMULATION
AMERICIUM 241
GEOLOGIC FRACTURES
ENVIRONMENTAL TRANSPORT
RADIOACTIVE WASTE MANAGEMENT
BASALT
SEDIMENTS
SENSITIVITY
SORPTION
RADIOCOLLOIDS
APERTURES
HYDRAULIC CONDUCTIVITY
IDAHO NATIONAL ENGINEERING LABORATORY
HYDRAULIC TRANSPORT
FLOODS
540250
540230
SITE RESOURCE AND USE STUDIES
RADIOACTIVE MATERIALS MONITORING AND TRANSPORT