Preliminary Dose Assessment for Emergency Response Exercise Using Unsealed Radioactive Contamination

A preliminary dose assessment for an emergency response exercise using unsealed radioactive sources was performed based on conservative calculation methods. The assessment was broken into four parts: activation, distribution, exercise participation, and post-exercise monitoring. The computer code MicroShield was used to determine external exposure from the source during and after distribution. Internal exposure via inhalation and ingestion was estimated by assuming fractional intakes of activity and converting to dose using annual limits on intake and dose coefficients. It was determined from the dose assessment that a radionuclide-dependent range of 37 MBq to 1.5 GBq can be used to achieve detectable dose rates during the exercise without exceeding assumed administrative dose limits. Of the identified radionuclides, Tc results in the lowest dose and is recommended from a radiological safety standpoint. However, the choice of which radionuclide and what activity to use for an exercise should be made based on budget and the logistics of the actual exercise.