A traditional field testing method to determine contaminant levels in materials such as soil, concrete, or paint for contaminating elements involves the use of x-ray fluorescence (XRF). The substantial absorption effects in the material matrix are corrected for by using a complicated fundamental parameters algorithm. This method fails if the sample is obscured by coatings of paint, epoxy, etc. of unknown thickness and composition. A new method is under consideration that makes it possible to use XRF to accurately and quickly determine the absolute concentration of contaminants underneath coatings without knowledge of the composition or thickness of overlying coatings. The technique will allow a portable XRF instrument to be constructed that is capable of fast (< 1 minute) and accurate measurements of low-levels of heavy metal contamination that are obscured by overlying coatings. For example, sensitivities at the five to 10 ppm level are expected for mercury and lead. For uranium, plutonium, and other transuranium elements, sensitivities 65 of one to two, ug/cm2 are expected. Bycomparison, Nuclear Regulatory Commission-designated safety levels are 10, ug/cm2 for 235U and 60 ,ug/cm2 for 238U. In Phase I, the detection limits will be determined for surface contamination of (1) uranium, thorium, and mercu.-y, (2) typical fission products strontium, cesium, and iodine, and (3) chlorine. The detection limits will also be determined and the absorption correction algorithm tested for these contaminants when covered by coatings of varying composition and thickness. A high-resolution (200 eV at 20 keV), high count-rate, thermo electrically-cooled detection system will be developed and used for these measurements. Anticipated Results/Potential Commercial Applications as described by the awardee: The result of this project will be a portable XRF instrument capable of rapid elemental analysis with better sensitivities than current XRF instrumentation. In addition to being a valuable tool for DOE decommissioning activities, this instrument will be a very competitive addition to the commercial XRF instrumentation market for soil analysis, residential lead-paint analysis, Superfund site analysis, and scrap metals analysis.
