A Dual Germanium Detector System for the Routine Assay of Low Level Transuranics in Soil

As an outgrowth of previous work on soil radioassay, we have developed an automated assay system for determining the transuranic radionuclide content of soils, with particular interest in Pu. The system utilizes two commercial planar intrinsic germanium detectors in opposition. The large area of the detectors (2100 mm2) and the thinness of the detector crystals (7 mm) permit sensitive analysis of the L x-ray emission region of the transuranics (13-21 keV). With counting times of 5 hours, we obtain detection limits of <15 pCi/g for Pu and <0.1 pCi/g for 241Am.