Estudo da viabilidade da alteração da posição da câmara de fissão no reator IEA-R1

Abstract

Operating up to 5MW, the IEA-R1 reactor is the oldest and biggest research reactor in Brazil. Nowadays, the restrictions over the radioisotope production are imposed by factors such as post irradiation facilities and operating hours capability. In order to cope up with the growing demand for radiopharmaceuticals in the country, in special the Lutetium-177, there is an effort being made to increase the operational cycle of the reactor to a 14 days cycle being nine days of continued operation followed by five maintenance days. New hot cells are also in construction to support the post irradiation processes. The IEA-R1 nuclear safety channel employs a fission chamber with a uranium coating enriched in more than 90% of Uranium-235 and, the purchase of such a highly enriched material involves a series of commercial restrictions and great bureaucratic complexity, which add great difficulties when dealing with this equipment replacements. In this context, with the increase in the operational cycle in mind, it is necessary to evaluate the fission chamber behavior in this new environment, with the objective to minimize the depletion of the fissile material and extend its lifespan. This work focuses on investigate the thermal flux along the nuclear safety channel, in which the fission chamber is located, and search for optimal positions for its operation. To reach this objective, the reactor’s core was modelled using KENO-VI, a Monte Carlo based simulation tool from the SCALE Code System, developed and maintained by the Oak Ridge National Laboratory. Para atingir esse objetivo, o núcleo do reator foi modelado utilizando a ferramenta de simulação através do Método de Monte Carlo do pacote de software SCALE, desenvolvido e fornecido pelo Laboratório Nacional de Oak Ridge (Oak Ridge National Laboratory) chamada KENO-VI.