Speaker
Description
In this work, we present the design of the neutron collimation system for the high-resolution neutron powder diffractometer at IPEN/CNEN, named BÎAR (Brazilian Instrument of Adjustable Resolution). The IEA-R1 reactor is a 5 MW light-water-moderated research reactor located at the Institute for Energy and Nuclear Research (IPEN) in São Paulo, Brazil. The design of the collimation system constitutes the first stage in the development of BIAR, followed by the design of the beam monochromator and shielding systems. The conceptual design of BÎAR was guided by consultations with the Brazilian neutron diffraction user community to define instrument parameters optimized for the investigation of a broad range of materials. The project will also benefit from the expertise of companies specialized in neutron optics technologies and components. The development of BÎAR represents an important milestone for Brazilian neutron science, strengthening the national neutron user community while fostering the technical expertise required for the future instruments of the Brazilian Multipurpose Reactor (RMB). Following the development of a high-fidelity model of the IEA-R1 reactor using the MCNP6.3 (Monte Carlo N-Particle 6.3) code, we generated a virtual neutron source for the design and optimization of neutron instruments within the McStas (Monte Carlo Simulation of Triple-Axis Spectrometers) simulation framework. In this context, we propose a configuration of filters and shielding materials for neutron beam collimation and radiation protection, and we evaluate the impact of the selected design parameters on the radiation dose in the instrument operating area. Finally, we model the remaining major components of the diffractometer in the McStas environment, e.g., monochromator, collimators and instrument geometry, to assess their performance, feasibility, and availability from specialized suppliers.
Key Words
Collimation, shielding, Monte Carlo simulations