Award Date

1-1-1998

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geoscience

First Committee Member

Roko Andricevic

Number of Pages

66

Abstract

Radionuclide Dose Assessment of Groundwater Migrating from the Benham Event, NTS; a Solute Flux Approach presents results of a preliminary dose-based modeling study of radionuclide transport from the Benham subsurface nuclear detonation at the Nevada Test Site. This investigation utilized a radiologic source term generated from publicly available data and consists of forty-two radionuclides that may be present in sufficient quantities to pose a potential human health risk at the source. To avoid the complex near-cavity chemistry (e.g. solubility of actinides), conservative assumptions were used to estimate a hydrologic source term. By using a two-dimensional stochastic groundwater contaminant transport code, radionuclide transport was modeled from the Benham event to control planes 10, 20, and 28 km downgradient assuming a pulse injection. The 95% confidence level of peak flux-averaged concentration at the control plane was compared to species specific concentration thresholds that would produce a 4 mrem/yr committed effective dose equivalent assuming 2L/day groundwater ingestion. Species with predicted concentrations above threshold values were modeled to more distant boundaries, while species with predictions that fell below their respective threshold were eliminated from further consideration. Twenty of the initial forty-two radionuclides have predicted 95% level concentrations above threshold concentrations at Oasis Valley. Thirteen of these twenty are actinides. Actinide results are believed to be unreasonably high due to assumptions made regarding solubility and potential for colloidal transport. {dollar}\rm \sp{129}I,\ \sp{99}Tc,\ \sp{14}C,{dollar} and {dollar}\sp{36}\rm Cl{dollar} were identified as the radionuclides that have the most potential to exceed concentration thresholds at the assumed discharge location of Oasis Valley.

Keywords

Approach; Assessment; Benham; Dose; Events; Flux; Groundwater; Migrating; Nevada; Nevada Test Site; Radionuclide; Solute

Controlled Subject

Hydrology; Environmental sciences

File Format

pdf

File Size

1566.72 KB

Degree Grantor

University of Nevada, Las Vegas

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