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
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.
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.
Modification of TRANSURANUS fuel performance code in the ATF framework
2019 - ABE, ALFREDO Y.; MELO, CAIO; GIOVEDI, CLAUDIA; SILVA, ANTONIO T.
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 performance under normal operation conditions due to the thin oxide rich in chromium that acts as a protective layer. The assessment and performance of new fuel systems rely on experimental irradiation program and fuel performance code simulation, therefore the aim of this work is to contribute to the computational modeling capabilities in the framework of the ATF concept. The well-known TRANSURANUS fuel performance code that is used by safety authorities, industries, laboratories, research centers and universities was modified in order to support FeCrAl alloy as cladding material. The modification of the TRANSURANUS code was based on existing data (material properties) from open literature and as verification process was performed considering LOCA accident scenario.
Fuel performance of iron-based alloy cladding using modified TRANSURANUS code
2019 - GIOVEDI, CLAUDIA; MELO, CAIO; ABE, ALFREDO Y.; SILVA, ANTONIO T.; MARTINS, MARCELO R.
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 studied. This paper presents the results obtained using a modified version of the well-known TRANSURANUS code, obtained from the implementation of the stainless steel 348 properties as cladding material. The simulations were performed using data available in the open literature related to a PWR irradiation experiment. The results obtained using the modified version of the code were compared to those obtained using the original code version for zircaloy-4. The performance of both cladding materials was evaluated by means of the comparison of parameters such as gap thickness, fuel centerline temperature, internal pressure, and cladding stress and strain.
Sensitivity analysis of fuel rod parameters in steady state condition using TRANSURANUS code
2019 - AGUIAR, AMANDA A.; ABE, ALFREDO; GIOVEDI, CLAUDIA
In this paper, a simulation of steady state conditions using TRANSURANUS code applied to Arkansas Nuclear One Unit 2 (PWR) fuel rod is presented. The fuel rod considered in this work was exposed to a peak rod average burnup of 64 GWd/TU, which corresponds to a batch-average exposure of about 53 GWd/TU. TRANSURANUS code offers two different approach for sensitivity analysis: Numerical Noise Analysis and Monte Carlo. In this work, sensitivity analysis using Monte Carlo approach was considered in the range of fuel rod manufacturing parameters, such as internal and external radius of the cladding, external radius of the fuel, and filling gas pressure of the fuel rod, in order to verify some existing correlation with fuel centerline temperature, internal cladding temperature, average tangential stress in the cladding, average permanent tangential strain in the cladding, internal pressure, and fission gas release.
Neutron flux intercomparison and ex-core neutron detector optimization in a SMR reactor using MCNP6 code and MAVRIC sequence
2019 - SOUZA, GREGÓRIO; CARLUCCIO, THIAGO; SANCHEZ, PRISCILA; ABE, ALFREDO
Ex-core neutron detectors are commonly referred as a detector placed outside the reactor pressure vessel and in a typical SMR design its use is employed to reactor control. Due to its position (far from core) neutron flux calculation for ex-core detector purposes is challenging when using Monte Carlo codes, therefore this work presents an intercomparison between two Monte Carlo codes and also a neutron flux analysis (axially and radially) to better positioning the ex-core neutron detectors. Discrepancies regarding energy treatment can be evaluated as the MAVRIC sequence uses a set of cross sections in a multigroup energy structure while MCNP6 uses continuous energy. In this work, neutron flux intercomparison is mostly focused on variance reduction techniques since these codes presents different approaches, mainly because the MAVRIC sequence uses a hybrid approach combining deterministic and probabilistic methods and MCNP6 code uses traditional variance reduction methods. Some Monte Carlo variables such as figure-of-merit, CPU-time and error distributions maps are evaluated, and neutron flux magnitudes compared. To do so, a typical small modular reactor is modeled with the aid of MCNP6 code and the MAVRIC sequence in two different situations: one being a deep subcritical state with an external neutron source for variance reduction techniques comparison and the other a generic start up procedure (control rods removal) for detector position optimization.
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.

ALFREDO YUUITIRO ABE

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