Assessment of Cesium, Iodine, Strontium and Ruthenium isotopes behaviour in urban areas, after contamination from accidental release

The exposures of urban populations to the radiation derived from the deposition, after accidental atmospheric releases, of 137 Cs, 134 Cs, 129 I, 131 I, 133 I, 89 Sr, 103 Ru and 106 Ru were assessed, using the integrated system for the evaluation of environmental radiological impact in emergency situations, developed by the Instituto de Radioprotecao e Dosimetria (IRD)/Comissao Nacional de Energia Nuclear (CNEN). These radionuclide are fission products likely to be emitted in the occurrence of severe nuclear reactor accidents. Their environmental behaviour in urban areas, due to their deposition in soil, in urban surfaces and in vegetable-garden food products, such as leafy and non-leafy vegetables, were analyzed, and dose assessments at the short, medium and long terms were performed, with an without the application of protective measures for reduction of doses. Simulations of unitary initial deposition for each radionuclide and of two different potential accidents involving water reactors (PWR), with different source terms and distinct deposition for each radionuclide, were performed. Results were analyzed on the basis of relative relevance of radionuclides and pathways for the exposure of members of the public, as a function of age and time after the release. It was also performed an assessment of the effectiveness of protective measures as a function of the moment of their implementation. (author)