In monitoring effluent water leaving its sites, the United States Department of Energy (DOE) assays for alpha-emitting radionuclides (uranium and the transuranics) to ensure compliance with regulatory limits. Because alpha emissions can only be detected over a short range in water (approximately 40 micrometers), the conventional approach is to collect samples for processing in a central laboratory; a time-consuming and costly procedure ensures to separate and measure the radionuclides. Because of the sporadic nature of sampling processes, there is the possibility that a release may go undetected. We are addressing this issue by developing a real-time, field-deployable instrument. This device incorporates a proprietary film that selectively binds radionuclides from dilute aqueous samples. By combining the film with an appropriate alpha spectrometer, we have developed a fieldable system that can operate as an autonomous monitor in a batch or continuous manner. Laboratory results to date have been encouraging. Positive identification of uranium and plutonium has been made by resolving the energy spectrum of emitted alphas. Sensitivity for uranium is at the 10 part per trillion level (15 femtocuries per liter).
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