Field Method for Gross Alpha- And Beta- Emitting Radionuclide Detection in Environmental Aqueous Solutions

A new field method was developed for the gross detection of alpha and beta radionuclides in water. The new field, method consists of a 0.5 L water sample concentrated with an Actinide Resin (Eichrom Technologies, Inc.), followed by MnO2 co-precipitation, and detection on an Thermo Eberline E600 detection system utilizing a phoswich (ZnS:Ag) plastic scintillator mounted on a modified SPA-1A Probe (Thermo Eberline, LLC.) The field method was evaluated against a modified EPA method consisting of the iSolo® Alpha/Beta Counting System which utilized a passivated implanted planar silicon (PIPS) detector. The minimum detectable concentration (MDC) for the field method is 308.4 mBq L-1 and 730.2 mBq L-1, for alpha and beta, respectively, compared to 3.0 mBq L-1 and 6.0 mBq L-1, respectively, for the standard method, EPA 900.0 [EPA, 2004]. The resulting MDC, relative to the standard method, was significantly higher. The proposed field method is most suitable for human health risk assessment vice environmental monitoring. Under the specified conditions, the goal was to quantify measurements at or below a determined gross activity action level to facilitate risk assessment decision-making. The reference levels set by the World Health Organization (WHO) are 500 mBq L-1 for gross alpha and 1,000 mBq L-1 for gross beta activities; water deemed acceptable for human consumption without any further action with respect to its radioactivity [Bartram and Gordon, 2006]. Furthermore, at these levels, additional analysis would be necessary for risk assessment to be quantified.