Radioecological questions concerning the monazite sand cycle wastes in Brazil

Nuclemon Minero Quimica (NMQ) is the Brazilian company responsible for monazite sand processing. Its activities result in wastes and by-products that are rich in radionuclides of the 232Th and 238U series, therefore, subjected to a special treatment. In this paper radiological surveys of three NMQ sites used for temporary or permanent storage of these materials have been described. The sites are: the Interlagos Mill in the City of Sao Paulo, the storage site at Botuxim (State of Sao Paulo) and the Praia Mill, on the northern coastal area of Rio de Janeiro State. A mesothorium (228Ra and 226Ra) storage site at the uranium mining and milling site of the Pocos de Caldas Industrial Company (CIPC), Minas Gerais State, is also discussed. The survey has indicated that all but the CIPC site became contaminated by radionuclides of the 232Th and 238U series from the by-products and wastes originating from the processing of the monazite bearing sands. 6 refs., 2 tabs., 7 figs