C. Teixeira - Academia.edu (original) (raw)

Papers by C. Teixeira

The Brazilian Multipurpose Reactor (RMB), now in the conception design phase, is being designed i... more The Brazilian Multipurpose Reactor (RMB), now in the conception design phase, is being designed in Brazil to attend the demand of radiopharmaceuticals in the country and conduct researches in various areas. The new reactor, planned for 30 MW, will replace the IEA-R1 reactor of IPEN-CNEN/SP. Low enriched uranium (<20% 235 U) UAl x dispersed in Al (plate geometry) and metallic uranium foil targets (plate and cylinder geometries) are being considered for production of Molybdenum-99 (99 Mo) by fission. Neutronic and thermal-hydraulics calculations were performed to compare the production of 99 Mo for these targets in the RMB. For the neutronic calculations were utilized the computer codes HAMMER-TECHNION, CITATION and SCALE and for the thermal-hydraulics calculations were utilized the computer code MTRCR-IEAR1 and ANSYS CFX.

Designs using thorium-based fuel are preferred when used in compliance with sustainable energy pr... more 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 (ThMOX). Applications of Th-MOX for light water reactors are possible due to inherent benefits over commercial fuels in terms of neutronic properties. The fuel proposed, (Th-Pu)O2, can be helpful because it would consume a significant fraction of existing plutonium. Aside from the reactor core, the proposed fuel could be useful in existing technology, such as in a pressurized water reactor (PWR). However, licensing codes cannot support Th-MOX fuel without implementing adaptations capable of simulating fuel behavior using the FRAPCON code. The (Th-Pu)O2 fuel should show a plutonium content that produces the same total energy release per fuel rod when using UO2 fuel. Tho...

In the framework of the Enhanced Accident Tolerant Fuel (EATF) program, one important tool to ass... more In the framework of the Enhanced Accident Tolerant Fuel (EATF) program, one important tool to assess the behaviour of new materials under irradiation is the use of fuel performance codes. For this, it is necessary to modify conventional fuel performance codes to introduce the properties of the materials to be studied. The aim of this paper is to present some preliminary results obtained using modified versions of the FRAPCON code adapted to evaluate the performance as cladding of two different types of iron-based alloys as cladding: stainless steel (AISI 348), and FeCrAl alloy, including a preliminary sensitivity analysis. The results obtained using the modified versions of the codes were compared to those obtained for zirconium-based alloys using the original code version. The results have shown and confirmed that iron-based alloys are one of the promising candidates to be used as EATF cladding in PWR.

FRAPCON code predicts fuel rod performance in LWR (Light Water Reactor) by modeling fuel response... more FRAPCON code predicts fuel rod performance in LWR (Light Water Reactor) by modeling fuel responses under normal operating conditions and anticipated operational occurrences; FRAPTRAN code is applied for fuel transient under fast transient and accident conditions. The codes are well known and applied for different purposes and one of the use is to address sensitivity analysis considering fuel design parameters associated to fabrication, moreover can address the effect of physical models bias. The objective of this work was to perform an assessment of fuel manufacturing parameters tolerances and fuel models bias using FRAPCON and FRAPTRAN codes for Loss of Coolant Accident (LOCA) scenario. The preliminary analysis considered direct approach taken into account most relevant manufacturing tolerances (lower and upper bounds) related to design parameters and physical models bias without considering their statistical distribution. The simulations were carried out using the data available i...

The IPEN/CNEN proposal for FUMAC-CRP was to modified fuel performance codes (FRAPCON and FRAPTRAN... more The IPEN/CNEN proposal for FUMAC-CRP was to modified fuel performance codes (FRAPCON and FRAPTRAN) in order to assess the behavior of fuel rod using stainless steel as cladding and compare to zircaloy cladding performance under steady state and accident condition. The IFA 6509, IFA-650-10 and UFA-650-11experiments were modelled to perform the LOCA accident simulation considering the original cladding and compared to stainless steel cladding.

The main challenge in the nuclear area since the Fukushima Daiichi accident is to develop fuel ma... more The main challenge in the nuclear area since the Fukushima Daiichi accident is to develop fuel materials to be applied in nuclear reactors aiming to increase the safety under normal operation as well as transient and accident conditions. These efforts are concentrated in the Advanced Technology Fuel (ATF) program that has as main scopes to study cladding materials to replace the zirconium-based alloys, and fuel materials presenting higher thermal conductivity compared to the conventional uranium dioxide fuel pellet. In this sense, iron-based alloys, which were used with a good performance as cladding material in the first Pressurized Water Reactors (PWR), have becoming a good option. The assessment of the behavior of different materials previously to perform irradiation tests, which are time consuming, can be performed using fuel performance codes, but for this, the conventional fuel performance codes must be modified to implement the properties of the materials that are being studi...

This study aims to investigate a fuel mixture of silicon carbide (SiC) and uranium dioxide (UO2) ... more This study aims to investigate a fuel mixture of silicon carbide (SiC) and uranium dioxide (UO2) and analyze performance when this fuel applies to light-water reactors (LWRs). Utilization of the licensing code, FRAPCON, with UO2 helped to determine the fuel response under normal conditions initially. High thermal conductivity could permit the use of UO2-10 vol% SiC fuel, showing thermal conductivity values that are far superior to the UO2 alone, exceeding 50% at 900 °C. Ultimately, the formulation should reduce gaseous fission products, avoid fuel cracking, and improve safety margins. SiC has excellent physical properties such as chemical stability, a cross-section with low absorption, irradiation resistance, and a higher melting point. There are some benefits for fuels that use carbon composites such as UO2-carbon nanotube (CNT), and UO2-diamonds. The pellets containing fractions of the carbon limit the amount of fissile U-235 and require additional enrichment to produce the same e...

Progress in Nuclear Energy, 2008

This paper presents an analysis of different options for the interim storage of research reactor ... more This paper presents an analysis of different options for the interim storage of research reactor spent fuels. The analysis' results showed a dualpurpose metallic cask as one of the most feasible options for the interim storage of the spent fuels of the IEA-R1 research reactor, located at IPEN-CNEN/SP, in Brazil. In case this reactor keeps its continuous operation at 5 MW in the next years, it will be necessary to transfer the spent fuels, today located in the reactor storage pool, to a spent fuels interim storage, until a definition of the Brazilian national policy on the final disposal of these spent fuels is established.

Progress in Nuclear Energy, 2008

In the last years, IPENeCNEN/SP has developed the project, technical specifications and the manuf... more In the last years, IPENeCNEN/SP has developed the project, technical specifications and the manufacturing of U 3 O 8 eAl and U 3 Si 2 eAl dispersion fuels. Non-destructive analysis techniques have been an important part of the qualification program of these fuels. Today, for utilization in the IEA-R1 research reactor core of IPEN, the U 3 O 8 eAl fuel is qualified up to a uranium density of 2.3 gU/cm 3 and the U 3 Si 2 eAl fuel up to a uranium density of 3.0 gU/cm 3. Also, analogous to the qualification process of U 3 O 8 eAl and U 3 Si 2 eAl fuels, an extended bibliography revision on the irradiation performance of UeMo alloy dispersed in aluminum matrix (Al) was carried out to establish a set of parameters that could help in the definition of the technical specifications for manufacturing of this type of fuel at IPEN aiming its posterior utilization in the IEA-R1 reactor. The irradiation performance aspects were associated to the neutronic and thermalehydraulics aspects in order to propose a new core configuration to the IEA-R1 research reactor using UeMo dispersion fuels. Core configurations using Ue10MoeAl fuels with uranium densities ranging from 3 to 8 gU/cm 3 were analyzed with the computational programs CITATION and MTRCR-IEA-R1. Core configurations for fuels with uranium densities ranging from 3 to 5 gU/cm 3 showed to be adequate to be used in IEA-R1 reactor and would present a stable in-reactor performance even at high burnup.

Brazilian Journal of Radiation Sciences, 2021

Accident tolerant fuels (ATF) has been studied since the Fukushima Daiichi accident in the resear... more Accident tolerant fuels (ATF) has been studied since the Fukushima Daiichi accident in the research efforts to develop new materials which under accident scenarios could maintain the fuel rod integrity for a longer period compared to the cladding and fuel system usually utilized in Pressurized Water Reactors (PWR). The efforts have been focused on new materials applied as cladding, then iron-base alloys appear as a possible candidate. The aim of this paper is to implement modifications in a fuel performance code to evaluate the behavior of iron-based alloys under Loss-of-Coolant Accident (LOCA) scenario. For this, initially the properties related to the thermal and mechanical behavior of iron-based alloys were obtained from the literature, appropriately adapted and introduced in the fuel performance code subroutines. The adopted approach was step by step modifications, where different versions of the code were created. The assessment of the implemented modification was carried out s...

The standard fuel system based on UO2–zirconium alloy has been utilized on nearly 90% of worldwid... more The standard fuel system based on UO2–zirconium alloy has been utilized on nearly 90% of worldwide nuclear power light water reactors. After the Fukushima Daiichi accident, alternative cladding materials to zirconium-based alloys are being investigated in the framework of accident tolerance fuel (ATF) program. One of the concepts of ATF is related to cladding materials that could delay the onset of high temperature oxidation, as well as ballooning and burst, in order to improve reactor safety systems, and consequently increase the coping time for the reactor operators in accident condition, especially under Loss-of-Coolant Accident (LOCA) scenario. The ferritic iron-chromium-aluminum (FeCrAl) alloys have been identified as an alternative to replace current zirconium-based alloys based on its outstanding resistance to oxidation under superheated steam environment due to the development of alumina oxide on the alloy surface in case of LOCA; moreover, FeCrAl alloys present quite well p...

Ciência & Saúde Coletiva, 2003

This study evaluated life and work conditions and their impact on the health and psychological de... more This study evaluated life and work conditions and their impact on the health and psychological development of adolescents. A number of 354 high school students, 14 to 18 years old, studying during evening period took part in this study. Data were collected using free evocation technique and questionnaires. Data on sleep during the weekdays were obtained using questionnaires, filled out by students regarding life and work conditions, health symptoms and illness. Data were analyzed with software EVOC 2000 for the social representations, and T-Student, ANOVA, Mann-Whitney e Kruskal-Wallis tests were employed for analyze health and sleep conditions. Differences were found among worker students who reported shorter mean sleep durations and: males, feeling sleepy at work and classes, referring to tougher psychological demands at work, working as salesperson, earning more than 1 minimum monthly wage, working more than 6 hours per day or 20 hours per week, working in noisy environment or polluted with gases and vapors. The representation of work among teen workers point a contradiction between recognizing work as a moral positive value to psychosocial development and identity construction, and the negative consequences due to precocious exposure to physical and psychological workloads.

The Brazilian Multipurpose Reactor (RMB), now in the conception design phase, is being designed i... more The Brazilian Multipurpose Reactor (RMB), now in the conception design phase, is being designed in Brazil to attend the demand of radiopharmaceuticals in the country and conduct researches in various areas. The new reactor, planned for 30 MW, will replace the IEA-R1 reactor of IPEN-CNEN/SP. Low enriched uranium (<20% 235 U) UAl x dispersed in Al (plate geometry) and metallic uranium foil targets (plate and cylinder geometries) are being considered for production of Molybdenum-99 (99 Mo) by fission. Neutronic and thermal-hydraulics calculations were performed to compare the production of 99 Mo for these targets in the RMB. For the neutronic calculations were utilized the computer codes HAMMER-TECHNION, CITATION and SCALE and for the thermal-hydraulics calculations were utilized the computer code MTRCR-IEAR1 and ANSYS CFX.

Designs using thorium-based fuel are preferred when used in compliance with sustainable energy pr... more 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 (ThMOX). Applications of Th-MOX for light water reactors are possible due to inherent benefits over commercial fuels in terms of neutronic properties. The fuel proposed, (Th-Pu)O2, can be helpful because it would consume a significant fraction of existing plutonium. Aside from the reactor core, the proposed fuel could be useful in existing technology, such as in a pressurized water reactor (PWR). However, licensing codes cannot support Th-MOX fuel without implementing adaptations capable of simulating fuel behavior using the FRAPCON code. The (Th-Pu)O2 fuel should show a plutonium content that produces the same total energy release per fuel rod when using UO2 fuel. Tho...

In the framework of the Enhanced Accident Tolerant Fuel (EATF) program, one important tool to ass... more In the framework of the Enhanced Accident Tolerant Fuel (EATF) program, one important tool to assess the behaviour of new materials under irradiation is the use of fuel performance codes. For this, it is necessary to modify conventional fuel performance codes to introduce the properties of the materials to be studied. The aim of this paper is to present some preliminary results obtained using modified versions of the FRAPCON code adapted to evaluate the performance as cladding of two different types of iron-based alloys as cladding: stainless steel (AISI 348), and FeCrAl alloy, including a preliminary sensitivity analysis. The results obtained using the modified versions of the codes were compared to those obtained for zirconium-based alloys using the original code version. The results have shown and confirmed that iron-based alloys are one of the promising candidates to be used as EATF cladding in PWR.

FRAPCON code predicts fuel rod performance in LWR (Light Water Reactor) by modeling fuel response... more FRAPCON code predicts fuel rod performance in LWR (Light Water Reactor) by modeling fuel responses under normal operating conditions and anticipated operational occurrences; FRAPTRAN code is applied for fuel transient under fast transient and accident conditions. The codes are well known and applied for different purposes and one of the use is to address sensitivity analysis considering fuel design parameters associated to fabrication, moreover can address the effect of physical models bias. The objective of this work was to perform an assessment of fuel manufacturing parameters tolerances and fuel models bias using FRAPCON and FRAPTRAN codes for Loss of Coolant Accident (LOCA) scenario. The preliminary analysis considered direct approach taken into account most relevant manufacturing tolerances (lower and upper bounds) related to design parameters and physical models bias without considering their statistical distribution. The simulations were carried out using the data available i...

The IPEN/CNEN proposal for FUMAC-CRP was to modified fuel performance codes (FRAPCON and FRAPTRAN... more The IPEN/CNEN proposal for FUMAC-CRP was to modified fuel performance codes (FRAPCON and FRAPTRAN) in order to assess the behavior of fuel rod using stainless steel as cladding and compare to zircaloy cladding performance under steady state and accident condition. The IFA 6509, IFA-650-10 and UFA-650-11experiments were modelled to perform the LOCA accident simulation considering the original cladding and compared to stainless steel cladding.

The main challenge in the nuclear area since the Fukushima Daiichi accident is to develop fuel ma... more The main challenge in the nuclear area since the Fukushima Daiichi accident is to develop fuel materials to be applied in nuclear reactors aiming to increase the safety under normal operation as well as transient and accident conditions. These efforts are concentrated in the Advanced Technology Fuel (ATF) program that has as main scopes to study cladding materials to replace the zirconium-based alloys, and fuel materials presenting higher thermal conductivity compared to the conventional uranium dioxide fuel pellet. In this sense, iron-based alloys, which were used with a good performance as cladding material in the first Pressurized Water Reactors (PWR), have becoming a good option. The assessment of the behavior of different materials previously to perform irradiation tests, which are time consuming, can be performed using fuel performance codes, but for this, the conventional fuel performance codes must be modified to implement the properties of the materials that are being studi...

This study aims to investigate a fuel mixture of silicon carbide (SiC) and uranium dioxide (UO2) ... more This study aims to investigate a fuel mixture of silicon carbide (SiC) and uranium dioxide (UO2) and analyze performance when this fuel applies to light-water reactors (LWRs). Utilization of the licensing code, FRAPCON, with UO2 helped to determine the fuel response under normal conditions initially. High thermal conductivity could permit the use of UO2-10 vol% SiC fuel, showing thermal conductivity values that are far superior to the UO2 alone, exceeding 50% at 900 °C. Ultimately, the formulation should reduce gaseous fission products, avoid fuel cracking, and improve safety margins. SiC has excellent physical properties such as chemical stability, a cross-section with low absorption, irradiation resistance, and a higher melting point. There are some benefits for fuels that use carbon composites such as UO2-carbon nanotube (CNT), and UO2-diamonds. The pellets containing fractions of the carbon limit the amount of fissile U-235 and require additional enrichment to produce the same e...

Progress in Nuclear Energy, 2008

This paper presents an analysis of different options for the interim storage of research reactor ... more This paper presents an analysis of different options for the interim storage of research reactor spent fuels. The analysis' results showed a dualpurpose metallic cask as one of the most feasible options for the interim storage of the spent fuels of the IEA-R1 research reactor, located at IPEN-CNEN/SP, in Brazil. In case this reactor keeps its continuous operation at 5 MW in the next years, it will be necessary to transfer the spent fuels, today located in the reactor storage pool, to a spent fuels interim storage, until a definition of the Brazilian national policy on the final disposal of these spent fuels is established.

Progress in Nuclear Energy, 2008

In the last years, IPENeCNEN/SP has developed the project, technical specifications and the manuf... more In the last years, IPENeCNEN/SP has developed the project, technical specifications and the manufacturing of U 3 O 8 eAl and U 3 Si 2 eAl dispersion fuels. Non-destructive analysis techniques have been an important part of the qualification program of these fuels. Today, for utilization in the IEA-R1 research reactor core of IPEN, the U 3 O 8 eAl fuel is qualified up to a uranium density of 2.3 gU/cm 3 and the U 3 Si 2 eAl fuel up to a uranium density of 3.0 gU/cm 3. Also, analogous to the qualification process of U 3 O 8 eAl and U 3 Si 2 eAl fuels, an extended bibliography revision on the irradiation performance of UeMo alloy dispersed in aluminum matrix (Al) was carried out to establish a set of parameters that could help in the definition of the technical specifications for manufacturing of this type of fuel at IPEN aiming its posterior utilization in the IEA-R1 reactor. The irradiation performance aspects were associated to the neutronic and thermalehydraulics aspects in order to propose a new core configuration to the IEA-R1 research reactor using UeMo dispersion fuels. Core configurations using Ue10MoeAl fuels with uranium densities ranging from 3 to 8 gU/cm 3 were analyzed with the computational programs CITATION and MTRCR-IEA-R1. Core configurations for fuels with uranium densities ranging from 3 to 5 gU/cm 3 showed to be adequate to be used in IEA-R1 reactor and would present a stable in-reactor performance even at high burnup.

Brazilian Journal of Radiation Sciences, 2021

Accident tolerant fuels (ATF) has been studied since the Fukushima Daiichi accident in the resear... more Accident tolerant fuels (ATF) has been studied since the Fukushima Daiichi accident in the research efforts to develop new materials which under accident scenarios could maintain the fuel rod integrity for a longer period compared to the cladding and fuel system usually utilized in Pressurized Water Reactors (PWR). The efforts have been focused on new materials applied as cladding, then iron-base alloys appear as a possible candidate. The aim of this paper is to implement modifications in a fuel performance code to evaluate the behavior of iron-based alloys under Loss-of-Coolant Accident (LOCA) scenario. For this, initially the properties related to the thermal and mechanical behavior of iron-based alloys were obtained from the literature, appropriately adapted and introduced in the fuel performance code subroutines. The adopted approach was step by step modifications, where different versions of the code were created. The assessment of the implemented modification was carried out s...

The standard fuel system based on UO2–zirconium alloy has been utilized on nearly 90% of worldwid... more The standard fuel system based on UO2–zirconium alloy has been utilized on nearly 90% of worldwide nuclear power light water reactors. After the Fukushima Daiichi accident, alternative cladding materials to zirconium-based alloys are being investigated in the framework of accident tolerance fuel (ATF) program. One of the concepts of ATF is related to cladding materials that could delay the onset of high temperature oxidation, as well as ballooning and burst, in order to improve reactor safety systems, and consequently increase the coping time for the reactor operators in accident condition, especially under Loss-of-Coolant Accident (LOCA) scenario. The ferritic iron-chromium-aluminum (FeCrAl) alloys have been identified as an alternative to replace current zirconium-based alloys based on its outstanding resistance to oxidation under superheated steam environment due to the development of alumina oxide on the alloy surface in case of LOCA; moreover, FeCrAl alloys present quite well p...

Ciência & Saúde Coletiva, 2003

This study evaluated life and work conditions and their impact on the health and psychological de... more This study evaluated life and work conditions and their impact on the health and psychological development of adolescents. A number of 354 high school students, 14 to 18 years old, studying during evening period took part in this study. Data were collected using free evocation technique and questionnaires. Data on sleep during the weekdays were obtained using questionnaires, filled out by students regarding life and work conditions, health symptoms and illness. Data were analyzed with software EVOC 2000 for the social representations, and T-Student, ANOVA, Mann-Whitney e Kruskal-Wallis tests were employed for analyze health and sleep conditions. Differences were found among worker students who reported shorter mean sleep durations and: males, feeling sleepy at work and classes, referring to tougher psychological demands at work, working as salesperson, earning more than 1 minimum monthly wage, working more than 6 hours per day or 20 hours per week, working in noisy environment or polluted with gases and vapors. The representation of work among teen workers point a contradiction between recognizing work as a moral positive value to psychosocial development and identity construction, and the negative consequences due to precocious exposure to physical and psychological workloads.