Decommissioning aspects in the design phase of the Brazilian multipurpose reactor - RMB

Nowadays, there are four research reactors operating in Brazil. The production of radioisotopes occurs mainly in IEA-R1, a research reactor with five megawatts of thermal power, installed in the unit of the CNEN in Sao Paulo, the Nuclear and Energy Research Institute (IPEN). This reactor, however, does not supply the Brazilian radioisotopes demand for medical applications. This necessity can be supplied by the construction and operation of the Brazilian Multipurpose Reactor - RMB, now in the design phase. Another point that stands out the importance of the RMB is the fact of the IEA-R1, whose first criticality was reached in September 1957, to have a useful life of approximately more ten years. Therefore, it becomes indispensable the construction of a reactor that substitutes it. Beyond the production of radioisotopes, the RMB also could be used for structural materials and fuel irradiation tests as well as for accomplishment of research with neutron beams. Among several tasks, an important point that is already being considered in the design phase of the new reactor is its future decommissioning. The main concern is to take into account the lessons learned and the worldwide accumulated experience in the decommissioning of research reactors avoiding mistakes and reducing the amount of problematic wastes in the future. In spite of the currently lack of specific regulatory legislation with respect of reactors decommissioning, in this paper are presented the approach adopted to face the decommissioning task in the design of the new reactor as well as a summary of the Brazilian regulatory licensing procedures and recommendations. (author)