New article published in 12(4B) - ENFIR/INAC 2024

Modeling nuclear fuel assemblies through porous zones in a Small Modular Reactor: fluid dinamic considerations

Abstract: This work aims to qualify the use of porous zones for representing fuel assemblies of a proposed SMR reactor in numerical models to reduce the computational demand required to study these structures. It employs computational fluid dynamics (CFD) methods to calculate the conservation equations of mass, momentum, and energy within a control volume. Initially, a detailed fuel assembly geometry was created and used for isothermal simulations. The coefficients of porosity and pressure drop of the system were calculated based on the pressure drop and velocity results. These were then utilized to configure a second, simpler geometry of hexahedrons divided into thirteen sub-regions according to their cross-sectional area, each having different porosities and pressure drop coefficients. Finally, the results of the two simulations were compared to verify their convergence and allow the use of porous geometry. The outcomes suggest that, for models with a control volume significantly larger than a single fuel assembly, such as a complete nuclear reactor vessel, the use of porous zones is advantageous, as the variations in average velocity and pressure drop along the length of the structure are minor, with the maximum axial velocity variation of -10.99%. However, if the objective is to conduct a more detailed analysis of the entire assembly, this strategy is not recommended since some specific aspects of fluid behavior are not well captured, such as radial velocity differences. Read full article. 

Protocol for handling contaminated maritime cargo returned to the country

Abstract: Responding to nuclear and radiological incidents is part of the attributes of the Agency whose mission is nuclear and radiological safety; in the Brazilian case, the National Nuclear Energy Commission (CNEN), an autonomous structure of the Ministry of Science, Technology and Innovation (MCTI), Brazil. In 2022, the Nuclear and Radiological Emergency Response System (SAER) was activated to respond to a finding in a maritime container. The cargo, returned from abroad from a transshipment port, due to the detection of an internal radioactive source, arrived in the country at the Port of Suape, in Pernambuco; It was then analyzed by the CNEN technical team, following regulatory Norms and protocols. After work to remove the container of packed material – metal scrap – the radioactive source was located and identified, in the operation carried out in Caruaru-PE (headquarters of the metal scrap holding company). Immediately, it was collected at the Regional Center for Nuclear Sciences - Northeast (CRCN-NE), in compliance with the country's safety regulations. Qualified and well-trained teams resulted in reliability of the process. Read full article.