Masters Theses

Date of Award

12-1995

Degree Type

Thesis

Degree Name

Master of Science

Major

Nuclear Engineering

Major Professor

Laurence F. Miller

Committee Members

Peter Groer, David Simpson

Abstract

During the 1940's and 1950's a site in St. Louis, Missouri was used to store residue from uranium processing which was processed in the downtown St. Louis site (SLDS). This site was near the Lambert-St. Louis Airport and was called the St. Louis Airport Site (SLAPS). This site is presently under the United States Department of Energy's Formerly Utilized Sites Remedial Action Program (FUSRAP). Objectives of this program is to evaluate FUSRAP sites relative to public use, to determine remediation options, and to clean up these sites as necessary. This thesis performs a radiological assessment of the SLAPS and near by ballfield sites. In this radiological assessment a parameter uncertainty analysis is used to estimate exposures from four radionuclides for several pathways. To perform this radiological assessment, Argonne National Laboratory's RESRAD computer model (Version 5.6) was used to find the dose from the soil at SLAPS and the ballfield combined. RESRAD was also used to perform a sensitivity analysis. The sensitivity analysis identifies the most important parameters and pathways. The uncertainty analysis for this radiological assessment was performed by using Argonne National Laboratory's RESRAD-Probabilistic, which obtained cumulative probability distributions of dose for several pathways. A radiological assessment for off-site doses was performed by using the U. S. Environmental Protection Agency's (EPA) CAP88-PC computer model (Version 1.0). The four main contaminants of concern at the SLAPS and ballfield sites are Radium-226 (Ra-226), Uranium-238 (U-238), Thorium-232 (Th-232), and Thorium-230 (Th-230). For these sites to be considered clean, the Department of Energy (DOE) dose limit or the Environmental Protection Agency (EPA) risk limit must not be exceeded. One of the scenarios considered is whether the site could be used as a residential area. The concentration limits that satisfied the EPA limits for SLAPS and the ballfield, as residential areas, were 1 pCi/g for Ra-226, 125 pCi/g for U-238, 36 pCi/g for Th-230, and 2 pCi/g for Th-232. About 106,000 yd3 of contamination at SLAPS and about 176,000 yd3 of contamination at the ballfield must be removed to satisfy the EPA risk limit. Much of the concentration data provided by FUSRAP documentation had "less than" values for concentration rather than values with amount of uncertainty. If these "less than" values are omitted from the data, there would be about 71,000 yd3 of contamination at SLAPS and about 168,000 yd3 of contamination at the ballfield that would need to be removed for these sites to be used as residential areas.

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