RMB experimental program on the hydrodynamical behavior of fuel assemblies

The Brazilian Multipurpose Reactor - RMB is a 30 MW pool type research reactor, that uses Materials Testing MTR fuel assemblies. It has 5x5 square array core with 23 assemblies and two in-core irradiation positions, operating upward flow average velocities nearly 10 m/s in the plates channels. IEA-R1 5 which also 19 standard assemblies, four control central beryllium device. operates downward 1.8 In order to verify provide data information about dynamical behavior of under nominal critical conditions, experimental circuit ORQUÍDEA being designed. This will permit its parts be tested verified. Flow rate, temperature, pressure differential transducers are instruments circuit. Endurance velocity tests performed. COLIBRI designed make allow studies fluid-structure phenomenology similar those when subjected high velocities, can induce differences between channels formed by plates. work presents preliminary design for circuits built at Instituto de Pesquisas Energéticas e Nucleares IPEN Comissão Nacional Energia Nuclear CNEN.