PNNL

Abstract

Direct determination of 99Tc in groundwater using a sensor device represents a substantial challenge due to the short range of beta particles, the presence of radiological interferences, and low-level detection requirements. This paper describes a radiochemical sensing method for selective detection of 99Tc(VII) in water. The sensing approach uses dual-function composite sensor microcolumn that incorporates both selective sorption and scintillating properties. Analyte detection is carried out in a reagentless equilibration sensing regime using chemically unmodified groundwater. The sensor method was implemented in a prototypical probe device that integrates the sensor element, scintillation detection, data acquisition, and instrument control components in a single functional instrument compatible with a 3.5-inch well casing geometry. The feasibility of rapid 99Tc analysis in Hanford groundwater (Hanford Site, USA) below regulatory drinking water level of 33 Bq/L was demonstrated.