LUCIANO ONDIR FREIRE

LUCIANO ONDIR FREIRE

Página do item completo

Resultados de Busca

Agora exibindo 1 - 10 de 15

A preliminary proposal for a hybrid lattice confinement fusion-fission reactor for mobile nuclear power plants
2022 - FREIRE, LUCIANO O.; ANDRADE, DELVONEI A. de
Scientists detected 2.45-MeV neutrons and in smaller yields 4- and 5-MeV neutrons in deuterated metals under a 2.9-MeV electron beam. Such discovery could allow the use of deuterated metals at temperatures below their melting point to provide nuclear fusion reactions. Such reactions could provide fast neutrons and energy in the form of heat. This work analyzed the results of some experiments to infer the neutron multiplication rate in such environments. It also considered the possible roles that such phenomena could play in a commercial nuclear power reactor under economic and compactness constraints. It seems the best way to promote nuclear fusion is the irradiation of deuterated metals by fast neutrons. This work presents the concept of a hybrid fusion–fission reactor using fissile or fertile fuel to generate heat and fast neutrons along deuterated metals providing excess neutrons (reactivity boost). Additionally, deuterated metals also may have a role in neutron moderation requiring less volume than other moderators (water or graphite). Such a reactor, given its reactivity boost, may burn radioactive residuals (transmutation) at affordable costs while generating power. Alternatively, this hybrid fusion–fission concept could also breed fissile fuel from fertile isotopes using natural uranium as seed.
RANS-based CFD calculation for pressure drop and mass flow rate distribution in an MTR fuel assembly
2021 - SCURO, N.L.; ANGELO, G.; ANGELO, E.; UMBEHAUN, P.E.; TORRES, W.M.; SANTOS, P.H.G.; FREIRE, L.O.; ANDRADE, D.A.
This work presents a Reynolds-averaged Navier Stokes–based computational fluid dynamics methodology for the calculation of pressure drop and mass flow rate distribution in a material test reactor flat-plate-type standard fuel assembly (SFA) of the IEA-R1 Brazilian research reactor to predict future improvements in newer SFA designs. The results improve the understanding of the origin of fuel plate oxidation due to high temperatures, and consequently, due to the internal flow dynamics. All numerical analyses were performed with the ANSYS-CFX® commercial code. The observed results show that the movement pin decreases the central channel mass flow due to the length of the vortex at the inlet region. However, the outlet nozzle showed greater general influence in the flow dynamics. It should have a more gradual cross-section transition being away from the fuel plates or a squarer-shaped design to get a more homogeneous mass flow distribution. Optimizing both regions could lead to a better cooling condition. The validation of the IEA-R1 numerical methodology was made by comparing the McMaster University’s dummy model experiment with a numerical model that uses the same numerical methodology. The experimental data were obtained with laser Doppler velocimetry, and the comparison showed good agreement for both pressure drop and mass flow rate distribution using the Standard k-ω turbulence model.
Preliminary survey on cold fusion
2021 - FREIRE, LUCIANO O.; ANDRADE, DELVONEI A. de
Since 1989 the announcement of “cold fusion” by Stanley Pons and Martin Fleishmann, “cold fusion” field has been surrounded by controversy. After three decades, this field is alive and has produced thousands of publications, most in dedicated periodic and conferences. This work aims at checking whether “cold fusion” fits in pathological science traits. For each type of experiment and year, this work counted the distinct research groups results (success or failure). Experimental results from many research groups suggest that nuclear reactions in solids are more complex than fusion (it is not only fusion) and that they need energy triggers like background radiation, meaning chemical configurations alone do not seem to generate nuclear reactions. Some types of experiments present rising trends (the field does not fit in pathological science model) and have potential to bring disruptive technologies. If confirmed, experimental results will require revisions of accepted nuclear models.
Novel technological developments with impacts on perspectives for mobile nuclear power plants
2021 - FREIRE, LUCIANO O.; ANDRADE, DELVONEI A. de
New research developments suggest that nuclear reactors using fusion may enter the market sooner than imagined even for mobile applications, like merchant ship propulsion and remote power generation. This article aims at pointing such developments and how they could affect nuclear fusion. The method is enumerating the main nuclear reactors concepts, identifying new technological or theoretical developments useful to nuclear field, and analysing how new recombination could affect feasibility of nuclear fusion. New technologies or experimental results do not always work the way people imagine, being better or worse for intended effects or even bringing completely unforeseen effects. Results point the following designs could be successful, in descending order of potential: aneutronic nuclear reactions using lattice confinement, aneutronic nuclear reactions using inertial along magnetic confinement, hybrid fission-lattice confinement fusion, and fission reactions.
Novel aspects of constructal law
2021 - FREIRE, LUCIANO O.; ANDRADE, DELVONEI A. de
Constructal law explains the sense of evolution (morphing to get access to flows) of finite size systems, but paradoxes do exist as not all vegetables have a tree form. Also, nature does not improve all animals for displacement. This work aims at creating a model to explain those paradoxes about constructal law. It adopted the system engineering technique of segregation between functions (abstract goals) and solutions (physical entities). Further, this work introduced the assumptions of flow under external threats and imperfect channels (subject to leakages and suboptimal form). Results showed that there are always elements doing four functions in all types of channels: to reduce entropy, to protect channel, to retain integrity and to drive flow. Although the four functions are always present, natural systems typically privilege one function over others, depending on environmental demands. As a solution to improve flows, animal brains also fit in the model of four functions. Human mind seems to have groups of instincts associated with each of the four channel design functions, leading to four behavior phenotypes and four motivations (prominence, inclusiveness, negativity prevention and tradition). Finally, this model (channels need to meet four goals) unified physics and animal psychology and extended applications of Constructal law to the fields of systems engineering methods, management, and psychological science.
Potential advantages of molten salt reactor for merchant ship propulsion
2021 - FREITAS NETO, LUIZ G. de; FREIRE, LUCIANO O.; SANTOS, ADIMIR dos; ANDRADE, DELVONEI A. de
Operating costs of merchant ships, related to fuel costs, has led the naval industry to search alternatives to the current technologies of propulsion power. A possibility is to employ nuclear reactors like the Russian KLT-40S, which is a pressurized water reactor (PWR) and has experience on civilian surface vessels. However, space and weight are critical factors in a nuclear propulsion project, in addition to operational safety and costs. This work aims at comparing molten salt reactors (MSR) with PWR for merchant ship propulsion. The present study develops a qualitative analysis on weight, volume, overnight costs, fuel costs and nuclear safety. This work compares the architecture and operational conditions of these two types of reactors. The result is that MSR may produce lower amounts of high-activity nuclear tailings and, if it adopts the U233-thorium cycle, it may have lower risks of proliferating nuclear weapons. Besides proliferation issues, this 4th generation reactor may have lower weight, occupy less space, and achieve the same levels of safety with less investment. Thus, molten salt regenerative reactors using the U233-thorium cycle are potential candidates for use in ship propulsion.
Entering new markets
2021 - FREIRE, LUCIANO O.; ANDRADE, DELVONEI A. de
Nuclear ship propulsion and isolated islands energy supply are unexplored markets for nuclear vendors. Carbon taxes and fuel regulations may make fossil fuels more expensive. Such markets pay more for energy because of organization and transport costs and use of small machines, which are less efficient than grid generators. The goal of this work is to find the measures the nuclear industry needs to take to get into new potential markets. This work shows the different actors and their interests and points the natural or physical constraints they face. Considering interests and constraints, this work named the most probable market niches where nuclear power may beat other power sources. After considering natural constraints, this paper analyses human-generated constraints and presents a way on how to mitigate or solve them. This study shows that nuclear industry needs to take technical, administrative, and political measures before nuclear power arrives to a wider market. This work is based on literature review and qualitative analysis and cannot point precise thresholds where nuclear power should be competitive. Future work will consist of statistical analysis to find precise thresholds to help in the decision-making process.
Modeling dynamic scenarios for safety, reliability, availability, and maintainability analysis
2020 - GABE, CESAR A.; FREIRE, LUCIANO O.; ANDRADE, DELVONEI A. de
Safety analysis uses probability combinatorial models like fault tree and/or event tree. Such methods have static basic events and do not consider complex scenarios of dynamic reliability, leading to conservative results. Reliability, availability, and maintainability (RAM) analysis using reliability block diagram (RBD) experience the same limitations. Continuous Markov chains model dynamic reliability scenarios but suffer from other limitations like states explosion and restriction of exponential life distribution only. Markov Regenerative Stochastic Petri Nets oblige complex mathematical formalism and still subject to state explosions for large systems. In the design of complex systems, distinct teams make safety and RAM analyses, each one adopting tools better fitting their own needs. Teams using different tools turns obscure the detection of problems and their correction is even harder. This work aims to improve design quality, reduce design conservatism, and ensure consistency by proposing a single and powerful tool to perform any probabilistic analysis. The suggested tool is the Stochastic Colored class of Petri Nets, which supplies hierarchical organization, a set of options for life distributions, dynamic reliability scenarios and simple and easy construction for large systems. This work also proposes more quality rules to assure model consistency. Such method for probabilistic analysis may have the effect of shifting systems design from “redundancy, segregation and independency” approach to “maintainability, maintenance and contingency procedures” approach. By modeling complex human and automated interventional scenarios, this method reduces capital costs and keeps safety and availability of systems.
New formulation for semi-empirical correlations for penetration jets
2019 - PACHECO, R.R.; FREIRE, L.O.; ROCHA, M.S.; SCURO, N.L.; MENEZES, M.O.; ANDRADE, D.A.
Correlations for the extension of a water vapor jet injected in a liquid pool were historically proposed considering the mass flux (kg/m2/s) as a constant. The results were satisfactory, however adjusting the values by linear regression. Although, it presents the following drawbacks: 1) the formulation is only valid for the specific range of data for what it was created; 2) it does not allow the analytical evaluation of the heat transfer coefficient from the extension equation. This paper proposes a new formulation for the calculation of the mass flux, in such a way to remove both of these drawbacks.
Economically feasible mobile nuclear power plant for merchant ships and remote clients
2019 - FREIRE, LUCIANO O.; ANDRADE, DELVONEI A. de
Recent studies point to a reduction of atmospheric pollution using nuclear energy for merchant ships. This work examines the development of an economically competitive nuclear power solution for merchant ship propulsion. The solution also addresses the requirements of a wider market, like islands, offshore oil platforms, and remote cities. System engineering and analysis at various product breakdown levels also propose architectural options to improve competitiveness of nuclear power in mobile nuclear power plants (MNPPs). Analyses include market research on clients and technical considerations on nuclear energy costs. The results show that an enterprise that delivers electric power to remote clients and dedicates to management of all nuclear aspects seems to be the best organizational and technical choice. Besides, ships should be of modular type and the MNPPs should be easily detachable at sea. Only container ships and remote islands demand enough power to justify the use of nuclear power. Nuclear power has high probability to be economically competitive for large container ships, however, only if public policies impose levels of risks akin to other industries.

LUCIANO ONDIR FREIRE

Projetos de Pesquisa

Unidades Organizacionais

Cargo

Filtros

Autor

Assunto

Ano de publicação

Tipo de publicação

Periódico

Fator de Impacto (Web of Science)

Percentil (Web of Science)

Agência de fomento

Âmbito

Tipo de acesso

Tem arquivos

Configurações

Ordenar por

Resultados por página

Resultados de Busca