Incineration of Urban Solid Waste Containing Radioactive Sources

Incineration of urban solid waste accidentally contaminated by orphan sources or radioactive material is a potential risk for environment and public health. Moreover, production and emission of radioactive fumes can cause a heavy contamination of the plant, leading to important economic detriment. In order to prevent such a hazard, in February 2004 a radiometric portal for detection of radioactive material in incoming waste has been installed at AMSA (Azienda Milanese per i Servizi Ambientali2) “Silla 2” urban solid waste incineration plant of Milan. Radioactive detections performed from installation time up to December 2006 consist entirely of low-activity material contaminated from radiopharmaceuticals (mainly 131I). In this work an estimate of the dose that would have been committed to population, due to incineration of the radioactive material detected by the radiometric portal, has been evaluated. Furthermore, public health and environmental effects due to incineration of a high-activity source have been estimated. Incineration of the contaminated material detected appears to have negligible effects at all; the evaluated annual collective dose, almost entirely conferred by 131I, is indeed 0.1 man mSv. Otherwise, incineration of a 3,7 1010 Bq (1 Ci) source of 137Cs, assumed as reference accident, could result in a light environmental contamination involving a large area. Although the maximum total dose, owing to inhalation and submersion, committed to a single individual appears to be negligible (less than 10−8 Sv), the environmental contamination leads to a potential important exposure due to ingestion of contaminated foods. With respect to “Silla 2” plant and to the worst meteorological conditions, the evaluated collective dose results in 0,34 man Sv. Performed analyses have confirmed that radiometric portals, which are today mainly used in foundries, represent a valid public health and environmental protection also in urban waste incineration plants.