João Manoel Losada Moreira

Universidade Federal do ABC (UFABC) | UFABC · Energy Engineering

This work aims to present and analyze a new reactor core configuration for the IEA-R1 reactor core with the objective of enhancing its neutron irradiation capabilities. The reactor was modeled using the KENO-VI module from the SCALE Code System, provided by ORNL. Results have shown that implementing a near-cylindrical configuration in the IEA-R1 co...

A study on flywheels materials and geometries is presented here with the use of finite element modeling (FEM) simulations. The study analyzes the stress behavior of flywheel rotors subject to the rotational speed that creates the maximum stress that the flywheel can support, and then calculates the rotational energy mass ratio for each geometry. Th...

In the next future, several nuclear power plants would reach the end of operational life. Most of them are being evaluated for long-term operation, while the remaining should be permanently shut down. For these ones, it should exist a decommissioning fund large enough to cost the project. Since some plants delay to start to collect provisions for t...

A study on flywheel geometries is presented here with the use of finite element modelling (FEM) simulations. The study analyses the stress behaviour of flywheel rotors subject to the rotational speed that creates the maximum stress that the flywheel can support, and then calculates the rotational energy mass ratio (energy density) for each geometry...

The decommissioning is a complex, costly and hazard process which should be performed in the end of the operational life of a nuclear power plant aiming to reduce the risks offered due to its operation to the environment and public at large. Several kinds of activities are required, with the decontamination and dismantling comprising some of the mo...

The decommissioning of a nuclear power plant is a costly and highly complex process, requiring not only a planning and rigorous chronogram execution as well as funds large enough to cost it. The Long-Term Operation of the plant is not only interesting since it allows the plant to keep producing energy with low-carbon footprint as well as postpone t...

The THUNDER computer code allows performing thermal-hydraulic core analysis of pressurized water reactors aiming at the design and safety analysis of power and naval reactors in steady state and transient conditions. It uses the subchannel and control volume methods to perform a tridimensional analysis of the nuclear reactor core. The conservation...

This paper presents recent developments regarding micro reactors based on heat pipe technology.

This article presents how micro reactors can compete in the Brazilian micro generation market of electricity. The current installed capacity of nuclear power in Brazil is 2 GW while the fast growing micro generation (capacity < 75 kW) based on roof top units in residences and industrial and commercial buildings reached more than 4 GW in 2021. The m...

The Nuclear Power Plants (NPPs) had been seen as one of most important ways to produce energy to attend the increase demand without produce large amounts of energy without the Green House Gases (GHGs) emissions. Despite of the good perception of public regarding this energy source, there is still some problems and issues to be solved. One of them i...

The decommissioning process produces large volumes of different kinds of wastes, with different contamination and activation levels, requiring suitable management and facilities for nuclear waste storage and disposal. In certain situations, the storage and disposal facilities are not available at the time of the decommissioning while in others ther...

Heat Pipes (HPs) are components which had received new attention nowadays, becoming subject of intense research in areas such as nuclear and space exploration. This is mainly motivated due to its elevated capacity to move heat from a local to another without the inherent problems of complex systems and equipment such as pumps, compressors, pipes an...

A supressão de acidentes de trabalho depende de vários fatores comportamentais e institucionais dentro das empresas, normalmente resumidos como cultura de segurança, que incluem desde a utilização de equipamentos de proteção até o engajamento formal da alta direção. Redes Bayesianas permitem inferir por meio de um indicador o nível de cultura de se...

O consumo de energia está associado ao crescimento e desenvolvimento dos países e regiões. Um alto nível de consumo precisa de grandes quantidades de energia para atender a demanda dos bens e serviços. No entanto, com a dinâmica atual da sociedade tanto da produção quanto do consumo é difícil estabelecer uma única tese com relação à causalidade ent...

Brazil is constructing with national technology two small nuclear reactors for propulsion and for radioisotope production with thermal power levels between 20 and 50 MW. These nuclear reactors fit more in the class of small modular reactors (SMR) than in the class of large nuclear power plants. In this article we apply the design approach of SMRs t...

In this work a parametric study was carried to increase the production of radioisotopes in the IEA-R1 research reactor. The changes proposed to implement in the IEA-R1 reactor core were the substitution of graphite reflectors by beryllium reflectors, the removal of 4 fuel elements to reduce the core size and make available 4 additional locations to...

In the end of operational life, a nuclear power plant should be decommissioned to release its site for a new purpose. The decommissioning cost estimation is part of the decommissioning plan, which also include the decommissioning strategy definition. The cost estimation is performed by management tools, most of them according the bottom-up approach...

The nuclear industry requires specific safety qualification of electrical equipment in order to assure that they perform their function without experiencing common-cause failures. Electrical equipment used in the nuclear industry have been qualified according to IEEE 323 and IEC 60780 standards and their derivatives until 2016. Currently these two...

Waste management is a challenge currently faced by nuclear energy worldwide. Most nuclear power plants operate in a once-through cycle and all spent nuclear fuel is stored in long term. Fast reactors can recycle 96% of the material in spent nuclear fuel of thermal reactors, reducing drastically the time required to store the waste. The S-PRISM reac...

Presents the results, values and a tool to estimate the decommissioning cost of a nuclear power plant. The book is organized by: Reynaldo Palacios-Bereche, Federico Bernardino Morante Trigoso, Julio Carlos Teixeira, João Manoel Losada Moreira

The study of two-phase flow behavior is a very important requirement in nuclear reactor systems, due to it can appear during normal operating conditions in a BWR or fast and slow transients for both PWR and BWR reactors. This work presents the evaluation at steady-state of two-phase flow prediction performed by THUNDER code (Thermal-Hydraulic Unit...

Most part of nuclear power sites around the world has multiple reactors, requiring different approaches to deal with plants interdependencies during its decommissioning. Usually, decommissioning strategies are proposed based on previous experiences. A strategy that would organize the decommissioning process is often proposed based on previous exper...

O conceito de tolerância a falhas tornou-se importante nas últimas décadas na indústria nuclear devido à utilização de sistemas de Instrumentação e Controle (I&C) digitais. Uma falha é uma anomalia indesejada em um item ou sistema que pode levar a um estado inseguro e eventualmente gerar incidentes ou acidentes de consequências indesejáveis do pont...

O Brasil adotou inicialmente medidas de contenção da pandemia da COVID-19 e baixou a taxa de propagação estimada a partir do número total de casos confirmados. Entretanto tais medidas não obtiveram o apoio do governo federal e passaram a ser implementadas com pouca rigidez e hoje o país encontra-se em um momento crítico com número crescente de fata...

Managing the COVID-19 pandemic in the middle of the events requires real-time monitoring of its evolution to perform analyses of containment actions and to project near future scenarios. This work proposes a scheme to monitor the temporal evolution of the COVID-19 pandemic using the time series of its total number of confirmed cases in a given regi...

Apresenta um esquema para monitorar a evolução da pandemia da COVID-19 utilizando a série temporal do número total de casos confirmados. O parâmetro monitorado é a taxa relativa de variação temporal da série denominada de taxa de propagação. A capacidade de monitoramento da evolução da pandemia em uma região pelo esquema proposto é avaliada. Como a...

Social isolation measures reduce the population's infection rate with the COVID-19 virus, but its effectiveness is difficult to quantify. The successful control of the pandemic carried out by China and South Korea is studied using a scheme based on the net relative rate of infection which is very sensitive to sudden changes in the epidemic evolutio...

This work presents the feasibility studies to convert the UO2 core of the Westinghouse AP1000 reactor to a U/Th core aiming at U/Th fuel recycling. The focus of the work is to establish a first core which allows normal operation of the AP1000 reactor and investigate a possible route for generating the ²³³U for U/Th fuel recycling. The converted cor...

In the end of operational life, a nuclear power plant should be decommissioned to release its site for a new purpose. The decommissioning cost estimation is part of the decommissioning plan, which also include the decommissioning strategy definition. The cost estimation is performed by management tools, most of them according the bottom-up approach...

In this work a parametric study was carried out to increase the production of radioisotopes in the IEA-R1 reactor. One of the variables directly proportional to isotope production is the magnitude of the neutron flux in which some material is exposed, so the main objective of this work was to increase neutron flux, especially in the center of the r...

In this work we present some validation results for reactor core modeling with the Serpent code performed for the first cycle of the AP1000 reactor. The comparison with reported values of the assembly k ∞ for cold zero-power condition showed a discrepancy of 0.29%. The k ef for full-core static and burnup calculations of the very heterogeneous AP10...

The decommissioning of a nuclear power plant/site is a very complex process that is necessary to be performed at the end of its useful life to allow its release from regulatory control and a new use of the site by the society. Typically, a decommissioning project requires the management of several tasks and resources. In case of multiple reactors s...

Este trabalho discute a contribuição da energia nuclear para a complementação térmica do Sistema Interligado Nacional, as questões relacionadas com a usina Angra 3 em construção e analisa sua contribuição para a sustentabilidade do sistema elétrico. Neste trabalho avalia-se o valor estratégico da segurança energética provido pelas fontes termoelétr...

This work aims at the evaluation of two-phase flow calculations performed with the THUNDER code (Thermal-Hydraulic Unit of Numerical Development for Elements with Rod-bundles), a new computational code under development to perform a thermal-hydraulic analysis of LWR reactors with rod type fuel assemblies using UO2, and MOX of Th or Pu. This paper p...

This article presents the validation of the Code for Thermal-hydraulic Evaluation of Nuclear Reactors with Plate Type Fuels (COTENP), a subchannel code which performs steady-state thermal-hydraulic analysis of nuclear reactors with plate type fuel assemblies operating with the coolant at low pressure levels. The code is suitable for design analysis...

Universidade Federal do ABC-UFABC Palavras-Chave: Código SERPENT, validação, AP1000, venenos queimáveis, cálculos de queima. RESUMO O presente trabalho trata da realização de cálculos de validação para modelagem de núcleo de um reator PWR utilizando o código SERPENT. O reator estudado em questão foi o AP1000, da Westinghouse. O estudo foi voltado a...

This work evaluates the kinetic parameters of first order (exponential) models for methane generation in sanitary landfills in the subtropical region of São Paulo, SP. Specially for this purpose, a test cell was built. The temporal response function for the test cell’s methane generation was obtained over 600 days due to placement of municipal soli...

RESUMO O presente trabalho avalia os parâmetros cinéticos de modelos de primeira ordem (exponenciais) para geração de metano em aterros sanitários na região subtropical de São Paulo (SP). Construiu-se uma célula experimental especialmente para esse objetivo. A função resposta temporal da célula para geração de metano devido a uma deposição de resíd...

Este trabalho busca identificar e discutir um conjunto de instituições e arenas que possam fomentar a integração do setor elétrico na América do Sul por meio de agentes de mercado. Para operacionalizar a geração e comercialização de eletricidade foram identificadas 4 arenas e 5 organizações para acomodar os diferentes interesses e atividades dos ag...

This work presents the neutronics and thermal hydraulics feasibility to convert the UO2 core of the Westinghouse AP1000 in a (U-Th)O2 core, rather than the traditional uranium dioxide, for the purpose of reducing long-lived actinides, especially plutonium, and generates a stock pile of 233 U, which could in the future be used in advanced fuel cycle...

This article presents an estimation of the inventory of spent nuclear fuel from Angra 2 accumulated over the years. We consider for that two situations: a) the once-through fuel cycle, and b) a cycle with partial reprocessing to recycle the fissile material. The results show that there are currently about 400 ton of spent fuel stored in Angra 2, an...

This work presents the neutronics and thermal hydraulics feasibility to convert the UO2 core of the Westinghouse AP1000 in a (U-Th)O2 core by performing a parametric study varying the type of geometry of the pins in fuel elements, using the heterogeneous seed blanket concept and the homogeneous concept. In the parametric study, all geometry and mat...

O presente trabalho apresenta a possibilidade de adaptar um reator PWR, o conceito mais utilizado na atualidade, para que opere com combustível a base de mistura de óxidos de tório e urânio (Th, U)O2, ao invés do tradicional dióxido de urânio. O objetivo foi a redução de actinídeos de longa vida, em especial plutônio, e de gerar um estoque de 233 U...

This article describes the electricity consumption in Brazilian residences between 1985 and 2013 through linear regressions. The explanatory variables considered were the number of households, effective consumption of families as a proxy for family income, and electricity tariff for households. To deal with the power generation crisis of 2001 we ha...

This paper presents results of a methane balance assessment in a test cell built in a region with a subtropical climate near São Paulo, Brazil. Measurements and calculations were carried out to obtain the total methane emission to the atmosphere, the methane oxidation rate in the cover, and the total methane generation rate in the test cell. The ox...

The power generation sector in Brazil is usually considered to have a high level of sustainability because of its large share of hydropower, about 70%. The annual growth rate of the Brazilian power sector is about 4%/year with a growing capacity addition of fossil fuels, which indicates a deterioration regarding sustainability. This work utilizes m...

The decommissioning is an important part of a nuclear power plant life cycle which may occur by technical, economical or safety reasons. Decommissioning requires carrying out a large number of tasks that should be planned in advance, involves cost evaluations, preparation of plans of activity and actual operational actions. Despite the large number...

The decommissioning is an important part of every Nuclear Power Plant life cycle gaining importance when there are more than one plant at the same site due to interactions that can arise from the operational ones and a decommissioning plant. In order to prevent undesirable problems, a suitable strategy and a very rigorous schedule should implemente...

Presently at UFABC research are being conducted on the use of thorium mixed oxide in nuclear reactors. The nuclear codes that are being used for Reactor calculations are MCNP 5 and SCALE 5.1. In order to validate the master libraries used in these codes, mainly for the 232 Th and 233 U, we had calculated fast and thermal experimental critical bench...

Actually, Brazil have two operating Nuclear Power Plants and a third one under construction, all at Central Nuclear Almirante Álvaro Alberto - CNAAA. To comply with regulatory aspects the power plants operator, Eletronuclear, must present to Brazilian Nuclear Regulatory Agency, CNEN, a decommissioning plan. Brazilian experience with decommissioning...

An approximate analytical scheme is presented to estimate landfill methane emissions taking into account the oxidation that occurs in the soil cover. To facilitate the solution of the methane transport equation we introduce a region dependent coefficient to account for the methane oxidation. Expressions for the distribution of methane concentration...

Metal matrix composites have been considered promising candidates as nuclear fuels for pressurized water reactors and also for nuclear waste management. Among others, Zircaloy is considered an excellent alternative for metallic matrix in such composites due to its excellent mechanical properties, high thermal conductivity and high corrosion resista...

Neste traballo analízase a posibilidade de utilizar unha cota variable de royalty para inducir as empresas nunha contorna competitiva a preservar as reservas de petróleo. Inicialmente, desenvolveuse un modelo da evolución das reservas de petróleo, dispoñible para a extracción por un empresario en réxime de competencia, incluíndose na expresión do b...

The current nuclear power plants uses Uranium as a primary source of energy in an once through fuel cycle which, keeping the present uranium consumption, will be exhausted in the end of this century. To extend the utilization of uranium as source of energy, new concepts of evolutionary reactors and recycling of uranium and plutonium in thermal reac...

O descomissionamento de plantas nucleares é necessário no fim de sua vida útil. Sendo normalmente significativo o intervalo de tempo entre o início de suas operações e seu descomissionamento, devem ser considerados diversos parâmetros para um cálculo confiável do montante que custeará seu descomissionamento, custo este idealmente estimado antes do...

The decommissioning of a nuclear reactor requires several actions involving legal basis, decommissioning strategies, planning, dismantling, packing, transport and storage of a large volume of radioactive materials, qualified personnel and financial resources. The paper discusses the several aspects of these actions for the decommissioning of Angra...

The objective of this paper is to discuss the option of recycling and transmutation of radioactive waste against Once-through Fuel Cycle (OTC) based on uranium feed under the perspective of sustainability. We use a qualitative analysis to compare OTC with closed fuel cycles based on studies already performed such as the Red Impact Project and the c...

In this article we investigate producing Zirconium powder from discarded Zircaloy-4 material through the hydride–dehydride method. We restrict our study to the first part of the method, namely the hydrogenation process. Differential thermal analyses of the hydrogenation process of the Zircaloy-4 show that no hydrogen absorption occurs at temperatur...

Comparing power generation alternatives is not an easy task due to their different characteristics, and social and environmental impacts. Any comparative analysis requires a systematic procedure and adequate data considering the whole life cycle of the complete chain of electricity generation. In this work, we define intensity coefficients of elect...

This paper proposes a method, based on the artificial neural network technique, to predict accurately and in real time the power peak factor in a form that can be implemented in reactor protection systems. The neural network inputs are the position of control rods and signals of ex-core detectors obtained in the IPEN/MB-01 zero-power reactor. The r...

A Associação Brasileira de Energia Nuclear criou o Comitê de Rejeitos e Meio Ambiente com o objetivo de fazer um levantamento do estado da arte, em 2006, sobre o tratamento e armazenamento dos rejeitos radioativos no Brasil e no mundo. A solução de forma adequada da questão dos rejeitos radioativos é vista pela opinião pública como um ponto importa...

This paper proposes a method, based on the artificial neural network technique, to predict accurately and in real time the power peak factor in a form that can be implemented in reactor protection systems. The neural network inputs are the position of control rods and signals of ex-core detectors. The data used to train the networks were obtained i...

This paper aims to construct a data set that can be used to train neural networks to furnish the power density peak factor during reactor operation. The inputs considered were those available in the reactor protection systems, namely, the axial and quadrant power differences obtained from measured ex-core detector signals, and the position of contr...

This work presents results of robustness verification of artificial neural network correlations that improve the real time prediction of the power peak factor for reactor protection systems. The input variables considered in the correlation are those available in the reactor protection systems, namely, the axial power differences obtained from meas...

Dissertação (Mestrado).

In the last decade, Brazil started to operate facilities for processing and storing uranium in different forms. The necessity of criticality safety analysis appeared in the design phase of the uranium pilot process plants and also in the licensing of transportation and storage of fissile materials. The 2-MW research reactor and the Angra I power pl...

The RIVLAK code solves the one-dimensional transport equation for the radionuclide concentration within a body of water for routine and accidental releases of liquid effluents. A radionuclide dissolved in the water may disappear through stream advection, radioactive decay, adsorption by sediments floating in the water, adsorption by the bed of the...

Coordenadoria para Projetos Especals (COPESP) has been making an effort to develop a power distribution mapping system utilizing self-powered neutron detectors. The scheme adopted to estimate the power distribution is based on an expansion of lambda modes for a given reactor state. Two-dimensional lambda modes were obtained previously with a modifi...

Control rod worth measurements through the inverse kinetics equation depend on accurate determination of the amplitude function from detector signals. The modal-local method introduced in a previous study estimates space-time changes in the flux or shape function so that the amplitude function can be determined accurately and efficiently. A simple...

An efficient method has been developed to represent the space-time behavior of neutron detector signals in nuclear reactors. The method is based on a simplified solution to the neutron shape function in the framework of a quasi-static approximation to the time-dependent diffusion equation. The shape function is obtained as a sum of a modal expansio...

Space-time changes in the neutron flux or shape function at the detector location should be considered in rod worth measurements through the inverse kinetics equation. The modal-local method proposed in this study calculates the shape function, representing the localized perturbations due to reactor parameter changes. Once the lambda modes and loca...

Space-time changes in the neutron flux or shape function at the detector location should be considered in rod worth measurements through the inverse kinetics equation. The modal-local method proposed in this study calculates the shape function, representing the localized perturbations due to reactor parameter changes. Once the lambda modes and loca...

A system for on-line monitoring of power distribution in small reactors (known as MAP) is under development at COPESP-IPEN. Signals of self-powered neutron detectors are input to a program that estimates the power distribution as an expansion of lambda modes. The modal coefficients are obtained from a least-mean-squares technique adequate for real-...

Zirconium alloys are good options for the metal matrix in dispersion fuels for power reactors due to their low thermal neutron absorption cross-section, good corrosion resistance, good mechanical strength and high thermal conductivity. A necessary step for obtaining such fuels is producing Zr alloy powder for the metal matrix composite material. Th...

RESUMO: Este artigo apresenta o balanço de metano em uma célula experimenta de 35 x 30 m 2 com um dreno central de diâmetro de 0,6 m localizado na central de tratamento de resíduos CTR-Caieiras em São Paulo, Brasil. O balanço foi feito utilizando medidas da taxa de escape de metano através dreno e interface aterro-atmosfera. A vazão média de metano...

RESUMO A viabilidade de utilização da versão do programa FX2-TH existente no CTMSP para a análise de acidentes de inserção de reatividade em PWR é apresentada no presente trabalho. Para análise estática comparou-se os resultados obtidos com o FX2-TH com os resultados do programa CITATION, obtendo-se excelente concordância para o fator efetivo de mu...