INGESTION OF 226Ra FROM ACTIVATED PAINTS ON MILITARY EQUIPMENT: TRANSFER FACTORS AND DOSES

The use of Ra-226-activated markings was specific for military equipment some decades ago and the extent of possible internal exposure of former military personnel due to ingestion of Ra-226 is an issue of discussion. Whole-or partial-body counts are not sensitive enough to trace an overexposure due to a possible Ra-226 uptake four decades ago. Thus retrospective workplace assessments are needed. These are done by wiping tests with linen and skin pads on Ra-226 markings on decommissioned military equipment. The contamination investigations are performed in wipe-activity measuring cycles with exponentially increasing numbers of wipes. The activity wiped off does not increase with the number of wipes but levels off instead. Wipes with linen pads are more effective than wipes with skin. The skin-skin activity transfer is investigated by respective wipes too. The maximum committed dose in a typical scenario is calculated under worst case assumptions. For the typical work of 1 y an effective dose of about 70 mu Sv, and for the bone surface a dose of about 3 mSv, is obtained. Health Phys. 99(4):568-571; 2010