This article discusses outcome of research for deriving a methodology and apparatus for ascertaining for the presence of ultra-trace level actinides in air from their alpha emission signatures, while remaining blind to the relatively large (1,000× higher activity) alpha emissions from Rn-progeny. Apparatus and techniques were developed to collect and characterize alpha-emitting nuclides of Rn-progeny and actinides in air on a polycarbonate 3 m pore size continuous air monitor (CAM) filter. A wet-chemistry approach was developed and validated for successfully separating the Rn-progeny alpha emitting isotopes of Po-214 and Po-218, while extracting the actinides (U, Pu, Am) in a fluid mixture that is suitable for conduct of alpha spectroscopy with a centrifugally tensioned metastable fluid detector (CTMFD). The resulting α-TMFD technology was compared against the state-of-art "Alpha-SentryTM" Continuous Air Monitor (CAM) system commonly utilized world-wide. Results indicate that the α-TMFD technology can potentially offer complementary and superior performance in multiple performance categories, and ~18× improvement in the time to detect [e.g., at 0.02 Derived Air Concentration (DAC) within ~3 h, vs ~70 h for Alpha-SentryTM] for actinides of interest while also remaining ~100% blind to ~103× higher Rn-progeny background - with the added potential for offering few keV scale energy resolution without resorting to peak shape fitting, vs ~300-400 keV for existing CAM systems.
The hazard analysis and critical control point (HACCP) process is being widely adopted as a design, control, and operational methodology to maintain the reliability of delivering water quality that is safe for public health. This study applied the HACCP methodology to identify and assess the reliability of critical control points and critical monitors to manage acute and chronic health risks in potable reuse treatment trains. Specifically, a failure analysis was performed for full‐scale ultrafiltration and reverse osmosis critical control points to determine the reliability of critical monitors and their associated impacts on finished water quality. The results supported the use of ultrafiltration and reverse osmosis membranes as critical control points in potable reuse and identified the sensitivities of both current and emerging critical monitoring parameters, including turbidity, total organic carbon, ultraviolet absorbance at 254 nm, conductivity, fluorescence, calcium, sulfate, sucralose, and pressure decay tests.
This paper presents a novel and rapid, wet chemistry technique for spectroscopically detecting trace (∼10−3 Bq mL−1) level alpha emitting radionuclides mixtures with under 10 keV alpha energy resolution – with 100% gamma–beta rejection.
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