ALFREDO YUUITIRO ABE

ALFREDO YUUITIRO ABE

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Preliminary assessment of iron alloy cladding as accident tolerant fuel cladding
2019 - ABE, ALFREDO; TEIXEIRA, ANTONIO; SOUZA, DANIEL; GIOVEDI, CLAUDIA
Modification of fuel performance code to evaluate iron-based alloy behavior under LOCA scenario
2021 - GIOVEDI, C.; ABE, A.; MUNIZ, R.O.R.; GOMES, D.S.; SILVA, A.T.; MARTINS, M.R.
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 FRAPCON and FRAPTRAN fuel performance codes 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 simulating an experiment available in the open literature (IFA-650.5) related to zirconium-based alloy fuel rods submitted to LOCA conditions. The obtained results for the iron-based alloy were compared to those obtained using the regular version of the fuel performance code for zircaloy-4. The obtained results have shown that the most important properties to be changed are those from the subroutines related to the mechanical properties of the cladding. The results obtained have shown that the burst is observed at a longer time for fuel rods with iron-based alloy, indicating the potentiality of this material to be used as cladding with ATF purposes.
The IPEN/CNEN contribution to IAEA FUMAC benchmark using modified fuel performance code based on stainless steel as cladding under steady state, transient and accident conditions
2020 - ABE, ALFREDO; SILVA, ANTONIO T. e; GIOVEDI, CLAUDIA; MELO, CAIO; GOMES, DANIEL de S.; MUNIZ, RAFAEL R.
The IPEN/CNEN (Brazil) participated in IAEA Coordinated Research Project on Fuel Modeling in Accident Conditions (FUMAC) among others 18 countries (Argentina, Belgium, Bulgaria, China, Czech Republic, Finland, France, Germany, Hungary, Italy, Japan, Norway, Republic of Korea , Russian Federation , Spain , Sweden , Ukraine and United States of America), which aim was focused in modelling, predicting and improving the understanding of the behaviour of nuclear fuel under accident conditions in order to better understanding and enhanced safety of nuclear fuel. A serie of LOCA (Loss of Coolant Accident) experiments data were made available for the participants to perform simulation using their fuel performance codes and the outcome gives an idea about fuel codes limitation considering LOCA simulation and possible improvement needed in the existing models related to LOCA condition.The IPEN/CNEN (BRAZIL) proposal for FUMAC-CRP was to modify existing fuel performance codes (FRAPCON and FRAPTRAN) considering stainless steel as cladding material and perform a simulation comparing to zircaloy cladding performance under steady state and accident condition. The HALDEN LOCA Experiments (IFA 650-9, IFA-650-10 and IFA-650-11) were selected and modeled to perform the LOCA accident simulation considering the original cladding (zircaloy) and compared to stainless steel cladding.
Fuel performance assessment of enhanced accident tolerant fuel using iron-based alloys as cladding
2018 - GIOVEDI, C.; MARTINS, M.R.; ABE, A.; MUNIZ, R.O.R.; GOMES, D.S.; SILVA, A.T.
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.
Assessment of high conductivity ceramic fuel concept under normal and accident conditions
2020 - GOMES, D.S.; ABE, A.; SILVA, A.T.; MUNIZ, R.O.R.; GIOVEDI, C.; MARTINS, M.R.
After the Fukushima Daiichi accident, the high conductivity ceramic concept fuel has been revisited. The thermal conductivity of uranium dioxide used as nuclear fuel is relatively low, as consequence fuel pellet centerline reaches high temperatures, high fission gas release rate, increase of fuel rod internal pressure reducing the safety thermal margin. Several investigations had been conducted in framework of ATF (Accident Tolerant Fuel) using different additives in ceramic fuel (UO2) in order to enhance thermal conductivity in uranium dioxide pellets. The increase of the thermal conductivity of fuel can reduce the pellet centerline temperature, consequently less fission gas releasing rate and the low risk of fuel melting, hence improving significantly fuel performance under accident conditions. The beryllium oxide (BeO) has high conductivity among other ceramics and is quite compatible with UO2up to 2200°C, at which temperature it forms a eutectic. Moreover, it is compatible with zircaloy cladding, does not react with water, has a good neutronic characteristics (low neutron absorption cross-section, neutron moderation). This work presents a preliminary assessment of high conductivity ceramic concept fuel considering UO2-BeO mixed oxide fuel containing 10 wt% of BeO. The FRAPCON and FRAPTRAN fuel performance codes were conveniently adapted to support the evaluation of UO2-BeO mixed oxide fuel. The thermal and mechanical properties were modified in the codes for a proper and representative simulation of the fuel performance. Theobtainedpreliminary results show lower fuel centerline temperatureswhen compared to standard UO2 fuel, consequently promoting enhancement of safety margins during the operational condition and under LOCA accident scenario.
Development and application of modified fuel performance code based on stainless steel as cladding under steady state, transient and accident conditions
2019 - ABE, ALFREDO; SILVA, ANTONIO T. e; GIOVEDI, CLAUDIA; MELO, CAIO; GOMES, DANIEL de S.; MUNIZ, RAFAEL R.
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 650- 9, 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.
Analysis of the combined effects on the fuel performance of UO2-BeO as fuel and iron-based alloy as cladding
2017 - GIOVEDI, CLAUDIA; ABE, ALFREDO; MUNIZ, RAFAEL O.R.; GOMES, DANIEL S.; SILVA, ANTONIO T. e; MARTINS, MARCELO R.
Iron-based alloys have been considered as promising candidate material to replace zirconium-based alloys as fuel cladding based on the previous experience of the first generation of pressurized water reactors (PWR). Moreover, the safety margins of nuclear fuels can be improved by means of additives in the fuel pellet, as beryllium oxide (BeO), due to the increase of the fuel thermal conductivity. These efforts are part of the accident tolerant fuel (ATF) program which aims to develop nuclear fuel systems with enhanced performance under normal operation, design-basis accident and severe-accident conditions. This paper addresses the combined effects on the fuel performance considering the BeO additive in the fuel pellet and stainless steel 348 as cladding material under steady-state and loss-of-coolant-accident (LOCA) scenario. The fuel performance simulation and assessment are conducted using modified versions of well-known fuel performance codes (FRAPCON/FRAPTRAN). The obtained results have shown that the studied fuel system (stainless steel cladding and UO2-BeO) enables an improvement in the main parameters associated to the fuel safety margins under steady-state irradiation as well as LOCA scenario.
Sensitivity assessment of fuel performance codes for loca accident scenario
2017 - ABE, ALFREDO; GIOVEDI, CLAUDIA; GOMES, DANIEL; SILVA, ANTONIO T. e; MUNIZ, RAFAEL O.R.; MARTINS, MARCELO
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 in the open literature related to the series of LOCA experiment performed at the Halden reactor (specifically IFA-650.5). The manufacturing tolerances associated to design parameters considered in this paper were: enrichment, cladding thickness, pellet diameter, pellet density, and filling gas pressure. The physical models considered were: fuel thermal expansion, fission gas release, fuel swelling, irradiation creep, cladding thermal expansion, cladding corrosion, and cladding hydrogen pickup. The results obtained from sensitivity analysis addressed the impact of manufacturing tolerances and physical models in the fuel cladding burst time observed for the IFA-650.5 experiment.
High density fuels using dispersion and monolithic fuel
2017 - GOMES, DANIEL S.; SILVA, ANTONIO T.; ABE, ALFREDO Y.; MUNIZ, RAFAEL O.R.; GIOVEDI, CLAUDIA
Fuel plates used in high-performance research reactors need to be converted to low-enrichment uranium fuel; the fuel option based on a monolithic formulation requires alloys to contain 6 – 10 wt% Mo. In this case, the fuel plates are composed of the metallic alloy U-10Mo surrounded by a thin zirconium layer encapsulated in aluminum cladding. This study reviewed the physical properties of monolithic forms. The constraints produced during the manufacturing process were analyzed and compared to those of dispersed fuel. The bonding process used for dispersion fuels differs from the techniques applied to foil bonding used for pure alloys. The quality of monolithic plates depends on the fabrication method, which usually involves hot isostatic pressing and the thermal annealing effect of residual stress, which degrades the uranium cubic phase. The preservation of the metastable phase has considerable influence on fuel performance. The physical properties of the foil fuel under irradiation are superior to those of aluminum-dispersed fuels. The fuel meat, using zirconium as the diffusion barrier, prevents the interaction layer from becoming excessively thick. The problem with dispersed fuel is breakaway swelling with a medium fission rate. It has been observed that the fuel dispersed in aluminum was minimized in monolithic forms. The pure alloys exhibited a suitable response from a rate at least twice as much as the fission rate of dispersions. The foils can support fissile material concentration combined with a reduced swelling rate.
Simulation of accident-tolerant U3Si2 fuel using FRAPCON code
2017 - GOMES, DANIEL S.; SILVA, ANTONIO T.; ABE, ALFREDO Y.; MUNIZ, RAFAEL O.R.; GIOVEDI, CLAUDIA
The research on accident-tolerant fuels (ATFs) increased after the Fukushima event. This benefitted risk management in nuclear operations. In this investigation, the physical properties of the materials being developed for the ATF program were compared with those of the standard UO2–Zr fuel system. The research efforts in innovative fuel design include rigorous characterization of thermal, mechanical, and chemical assessment, with the objectives of making the burnup cycle longer, increasing power density, and improving safety performance. Fuels must reach a high uranium density—above that supported by UO2—and possess coating that exhibits better oxidation resistance than Zircaloy. The uranium density and thermal conductivity of ATFs, such as U3Si2, UN, and UC, is higher than that of UO2; their combination with advanced cladding provides possible fuel–cladding options. An ideal combination of fuel and cladding must increase fuel performance in loss-of-coolant scenarios. The disadvantages of U3Si2, UN, and UC are their swelling rates, which are higher than that of UO2. The thermal conductivities of ATFs are approximately four times higher than that of UO2. To prevent the generation of hydrogen due to oxidation of zirconium-based alloys in contact with steam, cladding options, such as ferritic alloys, were studied. It was verified that FeCrAl alloys and SiC provide better response under severe conditions because of their thermophysical properties. The findings of this study indicate that U3Si2 and the FeCrAl fuel cladding concept should replace UO2–Zr as the fuel system of choice.

ALFREDO YUUITIRO ABE

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