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.