Suitability of portable radionuclide identifiers for emergency incorporation monitoring

The suitability of portable nuclide inspectors for incorporation measurements were tested with three probes (LaBr₃(Ce), NaI (Tl) and HPGe) differing in sensitive volume and energy resolution. The efficiencies for the measurement of whole-body and lung radionuclide burden were calibrated using a whole-body block phantom with traceable radionuclide sources of ⁶⁰Co, ¹³³Ba, ¹³⁷Cs, ¹⁵²Eu and ⁴⁰K. A standing geometry was chosen as it allows rapid positioning of persons for the measurements. Decision and detection limits were determined for the unshielded detector in a normal laboratory radiation environment according to ISO 11929 for ¹³⁴Cs, ¹³⁷Cs and ⁶⁰Co. The detection limits of all three probes were significantly higher compared to well-shielded dedicated whole-body monitors (HPGe and NaI(Tl)) using a sitting geometry. Nevertheless, lung and whole body burdens derived from dose constraints for routine and emergency conditions could be measured with all three probes with a counting time of one minute. (authors)