Giovanni Laranjo de Stefani

Federal University of Rio de Janeiro | UFRJ · Programa de Engenharia Nuclear - Poli/COPPE/UFRJ

This article analyzes the SWOT Matrix for the implementation of the AP-Th1000 reactor with thorium fuel, aiming at a future replacement of the current nuclear reactors that use uranium as fuel by thorium. There was a need for an in-depth study of the national and international literature linked to the Brazilian reality. After that, specific meeting...

One of the main challenges faced by nuclear power plants is the scarcity of U-235, the fissile isotope used in conventional nuclear reactors. While there is enough U-235 in the world to fuel current reactors, the demand for energy is increasing rapidly, especially in emerging economies like China and India, and this could lead to shortages in the f...

This paper presents an application of an approximate relationship be tween the Doppler broadening function based on the Maxwell-Boltzmann distribution and the deformed Doppler broadening function based on the generalized Kaniadakis distribution. The relationship is based on the effec tive temperature of the medium. The application is to the exempla...

This paper presents a literature review of the utilization of thorium as a nuclear fuel in Brazil. The initial section delves into the historical context, narrating the rich history of thorium studies in Brazil, including notable collaborations with France and Germany. Following this historical overview, concise summaries of recent theoretical stud...

This article proposes a Light Water Small Modular Reactor (LW-SMR) based on the seed-blanket concept with thorium fuel, utilizing Artificial Intelligence (AI) for optimization. The objectives include defining SMR parameters and developing parallel multi-objective AI models using Genetic Algorithm (GA) and Particle Swarm Optimization PSO. A GA has b...

Outcomes and achievements from researches orienting the future in nuclear fission technology: NFT-18: Brazil, Peru and Bolivia Nuclear Fission Technology in Brazil, Peru and Bolivia 1. Nuclear Energy in Brazil, Peru and Bolivia Brazil, Peru and Bolivia are neighboring countries with geographic borders in the northern region of Brazil and they are 3...

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...

This paper proposes a three-dimensional and single-phase model using computational fluid dynamics to study the thermal–hydraulic design limits of the AP-Th 1000 concept. This thermal–hydraulic study provides the engineering design limits of the hottest subchannel of the AP-Th 1000 concept during the first fuel cycle. The reactor successfully upheld...

This work aims on the development of a FORTRAN 90 code to solve the Loading Pattern Optimization Problem (LPOP) in the IEA-R1 research reactor at the Nuclear and Energy Research Institute (IPEN/CNEN-SP) in São Paulo, Brazil. The code integrates the Particle Swarm Optimization (PSO) method, with the current reactor calculation methodology. The objec...

The main goal of this study is to quantify the neutron flux redistribution in detectors and the shadowing effect between control rods by proposing an instrumental calibration factor for measurement, based on computer simulations. The MCNP code was used to simulate the rod drop experiment in the IPEN/MB-01 research reactor. A study of the reactivity...

This paper presents a method for establishing an equivalence relationship between the Doppler Broadening Function based on the Maxwell-Boltzmann Distribution and the Deformed Doppler Broadening Function, according to the generalised Tsallis Distribution, through an effective temperature T eff of the medium. The proposed method allows a precise calc...

Delays in the construction of nuclear reactors due to licensing issues have been a problem across the world, affecting projects in Finland, France, and the United States. Small Modular Reactors (SMRs) emerge as a transition between Generations III+ and IV in order to make nuclear energy more competitive with other energy sources, including renewabl...

This work compares the project costs of two possible decommissioning strategies for a hypothetical nuclear site with similar characteristics to the CNAAA reactors. The cost of the process is sensitive to the type of strategy adopted, as the type of strategy involves the duration of the process. Defining project strategy/duration and estimating cost...

Thorium had its golden age between the 1960s and 1980s through intensive studies on a global scale, with the aim of establishing a promising basis for future nuclear fuel cycles. However, after demonstrating the feasibility of fuel cycle concepts using thorium, the United States decided to focus their studies on liquid metal fast regeneration react...

Uranium dioxide (UO2) is the most used fuel in light water reactors. At present, a sizable cumulative experience exists regarding the use of UO2 as a fuel. However, UO2 has reduced thermal conductivity Experiments shown that adding a second phase with higher thermal conductivity will improve the thermal conductivity of mixed fuel. Materials such as...

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...

STC-MOX-Th (Simplified Thermal-Hydraulics Code-Mixed Oxide Thorium) is a program developed in a MATLAB environment that calculates the thermal design limits of a typical Pressurized Water Reactor (PWR), which is the temperature fuel pellet center and the Nuclear Boiling Ratio (DNBR). In addition, other temperature distributions and hydrodynamic coo...

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 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...

Designs using thorium-based fuel are preferred when used in compliance with sustainable energy programs, which should preserve uranium deposits and avoid the buildup of transuranic waste products. This study evaluates a method of converting uranium dioxide (UO2) to thorium-based fuel, with a focus on Th-Pu mixed oxide (Th-MOX). Applications of Th-M...

The present work carried out a thermohydraulic analysis of a typical fuel assembly of the reactor AP1000 changing the type of fuel, of UO 2 conventionally used for a mixture of oxides of (U,Th)O 2 realizing some simplifications in the original design, with the objective to develop of an initial methodology capable of predicting the thermohydraulic...

This work discusses a parametric study applied to nuclear power generation based on a mixed fuel formed by the composition of thorium-uranium oxide (Th-U)O2. Also, approached in this study the physical neutrons models of a fuel system composed of ThO2 75 wt% and UO2 25 wt%, with 19.5% enrichment of U-235. The thermodynamic features of the thorium-u...

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...

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...

Since the beginning of Nuclear Energy Development, thorium was considered as a potential fuel, mainly due to the potential to produce fissile 233U. Several Th/U fuel cycles, using thermal and fast reactors were proposed and are still under investigation. However, the technical feasibility to use thorium was made in PWR; the USA PWR Indian Point Rea...

This work presents a neutronic assessment to convert a Small Modular Reactor (SMR) with uranium core to the thorium mixed oxide core with minimum possible changes in the geometry and main parameters of SMR core. This option is due to most of SMR are designed to be strongly poisoned in the beginning of cycle and to have a long cycle. Thorium can be...

The paper deals with the utilization of thorium in nuclear reactors and associated fuel cycles. Emphasis is given in the utilization in PWR with a review of the main studies; the results of a study to convert an advanced PWR (AP 1000) to use a core with mixed uranium thorium oxide are discussed. The results show that the converted core (U-Th) O2 ha...

The IEA-R1 neutron and thermo-hydraulic calculation methodology is composed of 5 computational codes from the area of reactor physics, which have a symbiotic dependence on each other. Since the outputs of each code will be used to generate the input of the next code. The programs involved in this methodology are LEOPARD, HAMMER-TECHNION, TWODB, CIT...

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...

In order to project a nuclear reactor, the neutronic calculus must be validated, so that its thermal limits and safety parameters are respected. Considering this issue, this research aims to evaluate the APTh-100 reactor thermal limits. This PWR is a project developed in Universidade Federal do ABC (UFABC) using fuel composed of Uranium and Thorium...

Nowadays, worries about energy generation are not restricted only due to economic aspects but also its sustainability. More and more the center of debate involves the minimization of the waste and the better usage of natural resources. Plutonium produced in nuclear plants is usually considered a proliferating waste in need of disposal, but it could...

The CANDU (Canadian Deuterium Uranium) is a nuclear reactor developed by AECL (Atomic Energy of Canada Limited). The first small-scale reactor is known as NPD and was made in 1955 and commenced operation in 1962. It is a pressurized heavy water reactor and uses D2O as moderator and coolant and therefore uses natural uranium as fuel. There have been...

The HTGR (High Temperature Gas-cooled Reactor) is a 4th generation nuclear reactor and is fuelled by a mixture of graphite and fuel-bearing microspheres. There are two competitive designs of this reactor type: The German "pebble bed" mode, which is a system that uses spherical fuel elements, containing a graphite-and-fuel mixture coated in a graphi...

The molten salt reactors (MSRs) make use of fluoride salt as primary cooler, at low pressure. Although considered a generation IV reactor, your concept isn't new, since in the 1960 years the Oak Ridge National Laboratory created a little prototype of 8MWt. Over the 20th century, other countries, like UK, Japan, Russia, China and France also did res...

Para garantir a precisão e relevância dos cálculos feitos para estudos e aplicações em tecnologia nuclear, é imprescindível que as bibliotecas de seção de choque utilizadas nas simulações computacionais para modelagem estejam apropriadamente validadas. Para isso é necessário verificar se os dados nucleares de seção de choque são capazes de reproduz...

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...

The thermal limits of a PWR (pressure water reactor) are important physical quantities to be evaluated in order to verify if the nuclear design do not violate limits which would bring to damages in the fuel in operational conditions, as well as in transient and accidental conditions. This work shows the calculation of thermal limits of PWR nuclear...

The thermal limits of a PWR (pressure water reactor) are important physical quantities to be evaluated in order to verify if the nuclear design do not violate limits which would bring to damages in the fuel in operational conditions, as well as in transient and accidental conditions. This work shows the calculation of thermal limits of PWR nuclear...

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...

The AP-1000 is an evolutionary PWR reactor designed as an evolution of the AP-600 project. The reactor is already pre-licensed by NRC, and is considered to have achieved high standards of safety, possible short construction time and good economic competitiveness. The core is a 17x17 typical assembly using Zirlo as cladding, 3 different enrichment r...

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...

The AP-1000 is an evolutionary PWR reactor designed as an evolution of the AP-600 project. The reactor is already pre-licensed by NRC, and is considered to have achieved high standards of safety, possible short construction time and good economic competitiveness. The core is a 17x17 typical assembly using Zirlo as cladding, 3 different enrichment r...

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...

A neutron irradiator was assembled at IPEN (Nuclear and Energy Research Institute) facility to perform qualitative-quantitative analysis of materials, using thermal and fast neutrons. In order to determine the 116m In decay constant, a thermal flux obtained experimentally by Monte Carlo N-Particle Transport Code-MCNP, in a previous work, was used i...

The Nuclear and Energy Research Institute-IPEN, offers postgraduate programs, namely: Nuclear Technology-Applications (TNA), Nuclear Technology-Materials (TNM), Nuclear Technology-Reactors (TNR). The Institute programs mission is to form expert technicians and engineers with a strong knowledge in their discipline to work in the nuclear area. The co...

1 1 Instituto de Pesquisas Energéticas e Nucleares (IPEN / CNEN-SP) Av. Professor Lineu Prestes 2242 05508-000 São Paulo, SP tsantos@ipen.br gstefanni@ipen.br tnconti@ipen.br RESUMO O presente trabalho visa estudar a fenomenologia da circulação natural, que nada mais é do que a circulação do fluído sem auxilio de qualquer dispositivo mecânico. Esta...

This work objective was to create a manager program that would automate the programs and computer codes in use for neutronic calculation and thermo-hydraulic in IEA-R1 reactor thus making the process for calculation of safety parameters and for configuration change up to 98% faster than that used in the reactor today. This process was tested in com...

RESUMO Este trabalho tem como objetivo criar um software para automatizar o calculo do balanço térmico do Circuito de Circulação Natural (CCN) do Centro de Engenharia Nuclear do Instituto de Pesquisas Energéticas e Nucleares (CEN-IPEN). O balanço térmico é utilizado para avaliar as condições de um circuito de circulação natural, que é uma parte imp...

RESUMO O presente trabalho visa estudar a fenomenologia da circulação natural, que nada mais é do que a circulação do fluído sem auxilio de qualquer dispositivo mecânico. Esta circulação surge por causa da diferença de densidade entre a fonte quente e a fonte fria (sistema de remoção de calor). Com o auxilio do circuito de circulação natural do Cen...

Resumo. Este trabalho tem por objetivo a elaboração de um programa computacional, que gerencia a execução de vários programas da metodologia de cálculo neutrônico e termo hidráulico do reator IEA-R1, fazendo com que o processo fique mais prático e seguro. Com isso, tornando o tratamento dos dados de entrada e de saída de cada um dos programas, um p...

RESUMO Esse trabalho tem por objetivo a elaboração de um programa computacional que gerencie a execução de vários programas da metodologia de cálculo neutrônico e termo-hidráulico do reator IEA-R1, tornando o processo mais prático e seguro, além de tornar o tratamento dos dados de saída de cada um dos programas um processo automático. O reator IEA-...