ASSESSMENT OF INTAKE OF A COMPLEX RADIONUCLIDE BEARING DUST FORMED ATA NUCLEAR-POWER-PLANT

The aim of this work was to provide an experimental basis for assessin g intakes of an industrial actinide-bearing dust from measurements of Co-60 and Cs-137 in the body or urine. Whilst these radionuclides comp rised 72% and 19% of the radioactivity present, greater than 90% of th e committed effective dose will result from the low concentrations of the actinides present, 0.4%. To assess the dose coefficient for the du st and predict the biokinetics of Co-60 and Cs-137, in workers absorpt ion parameters for transfer from lungs to blood obtained from an anima l study were combined with information on particle deposition and clea rance from the ICRP human respiratory tract model and with tissue dist ribution and excretion data from the most recent systemic models. All other radionuclides were assumed to have Type M absorption characteris tics. The dose coefficient for the dust, 1.29.10(-7)Sv.Bq(-1) was esti mated to contain 113 kBq Co-60, 29 kBq Cs-137 and 0.64 kBq of the acti nides. The predicted retention and excretion characteristics of Co-60 and Cs-137 in workers after acute or chronic exposure to the dust sugg ested that measurements of these radionuclides in the body or urine co uld detect intakes equivalent to a few percent of an annual dose limit of 20 mSv.y(-1).