Improving Modeling of Iodine-129 Groundwater Contamination Plumes Using the System Assessment Capability
Years of production of radioactive materials at the Hanford Site in southeastern Washington State has resulted in contamination of surface, subsurface, and surface water environments. Cleanup of the site has been aided by various tools, including computer software used to predict contaminant migration in the future and estimate subsequent impacts. The System Assessment Capability (SAC) is a total systems tool designed to simulate the movement of contaminants from all waste sites at Hanford through the vadose zone, the unconfined aquifer, and the Columbia River. Except for iodine-129, most of the contaminants modeled by SAC have acceptably matched field measurements. The two most likely reasons for the inconsistency between the measured field data and SAC modeled predictions are an underestimated inventory and an overestimated sorption value (Kd). Field data tend to be point measurements taken from near the surface of the unconfined aquifer. Thus, the depth of the iodine-129 contamination plume on the site is not well characterized. Geostatistical analyses of the measured data were conducted to determine the mass of iodine-129 for four assumed plume depths within the unconfined aquifer. Several simulations for two different Kd’s using the initial SAC inventory were run to determine the effect of an overestimated sorption value on SAC modeled predictions. The initial SAC inventory was then increased for the two different Kd’s to determine the influence of an underestimated inventory on SAC modeled predictions. It was found that evidence for both an underestimated inventory and for an overestimated sorption value for iodine-129 exist. These results suggest that the Kd for iodine-129 should be reevaluated and that a more complete inventory must be generated in order to more accurately model iodine-129 groundwater contamination plumes that match available field data.
- Research Organization:
- DOESC (USDOE Office of Science (SC) (United States))
- Sponsoring Organization:
- USDOE Office of Science (SC)
- OSTI ID:
- 1051663
- Journal Information:
- Journal of Undergraduate Research, Vol. 4
- Country of Publication:
- United States
- Language:
- English
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