DEMONSTRATION OF USEFULNESS OF NEUTRON ACTIVATION ANALYSIS FOR ENVIRONMENTAL RESTORATION

The U.S. Department of Energy (DOE) is performing a Remedial Investigation/Feasibility Study (RI/FS) on East Fork Poplar Creek (EFPC) and its 670-acre floodplain that received an estimated 109,000 kg of mercury (Hg) and other contaminants from operations at the Y-12 Plant in Oak Ridge, Tennessee. A fast and inexpensive method was needed to analyze over 4000 soil samples from EFPC that are contaminated with mercury, other metals, and 235U and 238U. Because the creek potentially impacts over 100 private property owners, the investigation needs to collect data rapidly that can be used for characterization, risk assessment, and decisionmaking. A statistical methodology was developed that documents how neutron activation analysis (NAA) meets our project objectives and demonstrates to the U.S. Environmental Protection Agency (EPA) that NAA is equivalent (in terms of sensitivity, accuracy, and precision) to EPA's approved method of cold vapor atomic absorption (CV-AA) for Hg analysis. The sampling plan was designed to measure differences between and within locations in the floodplain, among and within stations at locations, among and within laboratories, and among methods. We demonstrated the equivalency of NAA to CV-AA and saved over $2M in total costs and over 7 months in analysis time by using NAA rather than CV-AA for this site.