Abstract: Brazil currently operates four research reactors, the most powerful of which is a 5 MW MTR-type reactor from the late 1950s, namely IEA-R1. Due to its limited neutron beam flux, this reactor offers only restricted scattering capabilities, featuring just a high-resolution diffractometer and an imaging system. To overcome these constraints, Brazil is constructing the Multipurpose Brazilian Reactor (RMB), a state-of-the-art 30 MW facility equipped with a cold neutron source and a dedicated neutron beam laboratory.
The RMB project is now underway, with the construction already in progress. Simultaneously, the neutron scattering laboratory is being developed, including team formation, design of the neutron guide hall, and the assembly of its first instrument: a high-resolution powder diffractometer.
The instrument project establishes the designing and assembling of it in the IEA-R1 neutron hall within the next three years. The construction of the diffractometer will be a first step to form a user community around the RMB neutron facilities. According to the project, the instrument will be definitively moved to RMB after its commissioning. The design and move of the diffractometer will be simulated by means of Monte Carlo-based software, viz., MCNP and McSTAS. Codes and methodology will be confirmed and adjusted experimentally at the IEA-R1 reactor with the high-resolution powder diffractometer Aurora.
Instruments will be neutron beam-supplied by thermal and cold guides that were designed to extract neutrons from inside the reactor reflector and the cold neutron source, respectively. The characterization and description of the thermal guides, i.e., thermal guides 1, 2, and 3 (TG1, TG2, and TG3), are also included in the current stage of the project. This study will also be carried out using Monte Carlo simulations, where the main goal consists of determining appropriate curvature and mirror inner revestment to guarantee line-of-sight exclusion to avoid epithermal neutrons and gammas at the neutron guide hall and efficient neutron beam transportation, respectively.
The performance of these topics will allow the creation of a first solid base for neutron scattering facilities in RMB by building a state-of-the-art diffractometer, consequently forming a neutron scattering user community in Brazil, and establishing a basic project for the guide system construction during future project stages.
