Development of a decision support system for siting a LILW and disused sealed sources disposal facilities in Brazil

The Brazilian National Nuclear Energy Commission, CNEN, is entrusted with the responsibility of safe management of radioactive wastes in Brazil. It has achieved this through stringent regulations, periodic inspections and regular collection and storage of waste from fuel cycle. On 20 November 2001, the President of Brazil approved Law 10308 which addresses site selection, construction and licensing, operation and enforcement of radioactive waste interim storage and final disposal in Brazil. Article 37, within this Law, demands that 'CNEN must begin studies for site selection, project, construction and licensing, to start operation within a period of time as short as technically possible, of a final disposal facility within national territory'. Currently, at CNEN research institutes there are interim storage facilities, which can warehouse approximately 500 m{sup 3} of low and intermediate level radioactive waste that stem from a large range of nuclear applications. It is estimated that the nuclear waste would grow at a rate of 50% every year for the next ten years. With this growth, the current capacity for interim storage will get depleted very quickly. In addition, about 8,000 disused sealed sources, formerly used in industrial gauge instruments, in research and in radiotherapy, have been collected as radioactive wastes. As part of the CNEN efforts to deal with the radioactive waste an IAEA technical co-operation project was established. This project aims at the development of an expert system as a decision support tool for selection of candidate sites for siting a national disposal facility for low and intermediate level institutional waste and spent sealed sources in Brazil. Due to limited funds for sites characterization, this expert system needs to be capable of dealing with vague and incomplete information while keeping a high degree of confidence in the results. (author)