2025 - PINTO, J.J.R.; MATTAR NETO, M.

There is much discussion today about the possibility of extending the lifetime of industrial plant components due to economic factors. Pressure vessels are among the most expensive components, and their replacement can significantly impact the operation of an entire plant. In this context, several Fitness-for-Service (FFS) methodologies can be applied to assess structural integrity, addressing not only economic aspects but also enhancing safety. Failure Assessment Diagrams (FADs) are widely used in FFS methodologies to prevent future failures by analyzing crack-type defects. These diagrams establish acceptability criteria based on the material toughness ratio and loading ratio. Recommended practices utilizing the BS-7910, API-579, and R6 methodologies are addressed in this work, alongside principles from fracture mechanics, material properties, and solid mechanics. The main objective was to develop computer programs in Matlab to analyze a case study involving a pressure vessel manufactured from SA-516 Gr 70 steel, determining the critical dimensions of semi-elliptical cracks in longitudinal and circumferential orientations of a cylindrical section. Level 2 evaluation, the most commonly used in FFS methodologies, was applied to develop the programs. This study enabled the creation of tools to automate calculations and generate FAD graphs, considering the critical depth and length of cracks. These tools support decision-making in structural design requirements and provide a means of evaluating equipment in service with crack-type defects, extending its operational lifetime. The FFS methodologies studied are based on ASME Codes for pressure vessels and piping, particularly Sections III and XI. Based on the analysis of API-579, BS-7910, and R6 methodologies under the operating conditions of the case study, it is possible to conclude that, for normal evaluations, critical length (2c) = 40.64 mm and critical depth (a) = 10.16 mm are acceptable values. However, for evaluations requiring safety considerations under the R6 procedure, applicable to Class A service equipment in the nuclear sector, only critical length (l) = 5 mm and depth (a) = 2.5 mm are permissible values.

2024 - PAULA, M.L. de; MORALLES, M.; GENEZINI, F.A.; SIQUEIRA, P.T.D.; RIBEIRO JUNIOR, I.S.; SILVA JUNIOR, I.A. da

This work was developed with the aim of improving the current sample exchange system of the BH-3 irradiation channel of the IEA-R1 reactor at IPEN. The instrument's operating concept will provide a better use of the irradiation space as well as greater safety and confidence to the operator. The development of the system involved 3D modeling, sizing, construction and non-destructive testing of the various parts, and analysis of neutron-induced activation of the materials most exposed to the beam. A programmable logic controller (PLC) was implemented for the system’s control inside a dedicated electrical panel that was built with materials compatible with the location. The system was designed to support samples weighing up to 15 kg. Bench tests were carried out and showed that the system performs the necessary functions to accurately position samples in three locations: outside the biological shield, at the irradiation channel and at the decay waiting station. The implementation of this instrument will contribute to the application of the ALARA principle in the operator activities at the BH-3 irradiation channel.

2024 - BARONI, D.B.; BORSOI, S.S.; SOARES, Y.S.A.; MATTAR NETO, M.; OLIVEIRA, P.S.P.; MATURANA, M.C.

This study examines nuclear regulation in the United Kingdom, focusing on licensing processes for land facilities supporting nuclear-powered submarines. It highlights the importance of these submarines for defense and maritime security, along with the need for specialized infrastructure to operate them safely and effectively. The study analyzes the UK’s procedures and regulations for nuclear licensing, with emphasis on regulatory bodies such as the Office for Nuclear Regulation (ONR) and the Defence Nuclear Safety Regulator (DNSR). Results discuss the classification of nuclear facilities in the UK, including those dedicated to submarines and nuclear defense, as well as the applicable standards and guidelines for licensing these facilities. It is concluded that nuclear regulation in the UK is robust and transparent, providing a solid foundation for licensing facilities supporting nuclear-powered submarines. The adoption of these standards as a reference in Brazil could significantly contribute to establishing a solid and secure regulatory framework for such facilities.

2024 - SANCHES, G.O.P.; ARAUJO, M.S.; MELLO-CASTANHO, S.R.

The immobilization of radioactive strontium (Sr) from liquid effluents, a byproduct of nuclear fission and accidents, presents significant environmental and public health challenges. This study evaluates the immobilization of Sr in a glass matrix by comparing the effects of different sintering temperatures. The analyses started from three temperatures 800ºC, 900ºC and 1000ºC for each of the four compositions, which vary the addition of niobium (Nb) content in the vitreous matrix by 2%, 4%, 6% and 8% in mol. The highest temperature was excluded because its deformation did not match the final objective, at 900ºC the compositions had better results in density and water absorption, so that at the same temperature the composition with 4% niobium responded better to the results. The study underscores the significance of treating temperature and Nb content in the glass matrix for effective Sr immobilization, offering valuable insights for the development of safe and sustainable nuclear waste management strategies.