NSUF - Nuclear Science User Facilities

Fabiola Cappia

Profile Information
Name
Dr. Fabiola Cappia
Institution
Idaho National Laboratory
Position
R&D Staff Scientist
h-Index
ORCID
0000-0002-7391-3500
Expertise
Accident Tolerant Fuel, High Burnup Fuel, Image Analysis, LWRS, Microindentation, Nuclear Fuel, Oxide Fuels, Raman, SEM
Publications:
"3D reconstruction of two-phase random heterogeneous material from 2D sections: An approach via genetic algorithms" Davide Pizzocri, Riccardo Genoni, Federico Antonello, Tommaso Barani, Fabiola Cappia, Nuclear Engineering and technology Vol. [unknown] Link
This paper introduces a method to reconstruct the three-dimensional (3D) microstructure of two-phase materials, e.g., porous materials such as highly irradiated nuclear fuel, from two-dimensional (2D) sections via a multi-objective optimization genetic algorithm. The optimization is based on the comparison between the reference and reconstructed 2D sections on specific target properties, i.e., 2D pore number, and mean value and standard deviation of the pore-size distribution. This represents a multi-objective fitness function subject to weaker hypotheses compared to state-of-the-art methods based on n-points correlations, allowing for a broader range of application. The effectiveness of the proposed method is demonstrated on synthetic data and compared with state-of-the-art methods adopting a fitness based on 2D correlations. The method here developed can be used as a cost-effective tool to reconstruct the pore structure in highly irradiated materials using 2D experimental data.
"Electron microscopy characterization of fast reactor MOX Joint Oxyde-Gaine (JOG)" Fabiola Cappia, Brandon Miller, Jeffery Aguiar, Lingfeng He, Daniel Murray, Brian Frickey, John Stanek, Jason Harp, Journal of Nuclear Materials Vol. 531 2020 Link
The composition and crystal structure of the “Joint Oxyde Gaine” (JOG) has been investigated by means of electron microscopy. Microstructural characterization reveals a highly heterogeneous porous structure with inclusions containing both fission products and cladding components. Major fission products detected, other than Cs and Mo, are Te, I, Zr and Ba. The layer is composed by sub-micrometric crystallites. The diffraction data refinement, together with chemical mapping, confirms the presence of Cs2MoO4, which is the major component of the JOG. However, combinatorial analyses reveal that other non-stoichiometric phases are possible, highlighting the complex nature of the crystalline structure of the JOG. Fe is found in metallic Pd-rich precipitates with structure compatible with the tetragonal structure of FePd alloy. Cr is found in different locations of the JOG, in oxide form, but no structural data could be obtained due to local beam sensitization of the sample in those areas.
"Electron microscopy characterization of the fuel-cladding interaction in medium burnup annular fast reactor MOX" Fabiola Cappia, Journal of Nuclear Materials Vol. 2021 Link
In this work, we present electron microscopy data focused on the fuel-cladding interaction layer in annular fast reactor MOX with HT-9 cladding at medium burnup. In agreement with previous literature data, the volatile fission products Cs, Te and I have migrated radially into the extreme fuel periphery and partially interacted with the cladding. The accumulation of Cs has occurred in the outermost rim of the fuel pellet, where grain recrystallization has also been observed. Significant amounts of Pd have been found in the interaction zone, particularly in the sample taken from the upper half of the fissile column where the cladding temperatures are higher. At this axial location, Cr has been enriched at the cladding inner surface and diffused into the fuel. Chromium remains mainly in metallic form, but locally formed oxides and the fission products Cs, Te and I are found, with variable composition, in form of nanocrystalline regions dispersed in the metallic Cr-rich layer. The morphology and chemical characteristics of the layer suggest a non-oxidative corrosion mechanism as principal cladding degradation phenomenon occurring in this sample, with local onset of Cr oxidation within the nanocrystalline precipitates.
"Post-irradiation examinations of annular mixed oxide fuels with average burnup 4 and 5% FIMA" Fabiola Cappia, Kosuke Tanaka, Masato Kato, Kenneth McClellan, Jason Harp, Journal of Nuclear Materials Vol. 533 2020 Link
We present post-irradiation examination results on two type of annular mixed oxide fuel pins irradiated in the Fast Flux Test Facility (FFTF) sodium cooled reactor to an average burnup between 4% and 5% fission of initial heavy atom (FIMA). The pins differed only from the initial Pu content, which was 22 wt% and 26 wt%, respectively. The overall performance of the pins was excellent, in line with previous historical results. The pins with higher Pu content experienced higher irradiation temperatures which influenced the fission gas release, fuel swelling, and Cs distribution compared to the other pins. All the post-irradiation examinations results are discussed against the irradiation parameters. In particular, the pins with higher initial Pu content, i.e., 26 wt%, experienced higher power that resulted in enhanced fission gas release compared to the other two pins with 22 wt% initial Pu content. For the pins with higher fission gas release, onset of Cs redistribution was observed. The two pins that had lower initial Pu content and burnup showed a Cs axial distribution similar to the as-produced one.
"Three-dimensional reconstruction from experimental two-dimensional images: Application to irradiated metallic fuel" Riccardo Genoni, Davide Pizzocri, Federico Antonello, Tommaso Barani, Lelio Luzzi, Jeffrey Giglio, Fabiola Cappia, Journal of Nuclear Materials Vol. [unknown] Link
This work applies reconstruction methods based on a genetic algorithm to derive 3D material properties, namely porosity and percolation fraction, in irradiated U-Pu-Zr fuel with minor actinides. We provide two-dimensional experimental data regarding the radial distribution of fission gas bubbles in the fuel and apply the algorithm successfully developed in a companion paper to reconstruct the fuel pore structure in 3D which is unknown a priori. The algorithm returned a set of best structures that constituted the best candidate solutions representing the pore phase. From these, it was possible to extract statistics on the 3D percolation fraction of the reference medium and infer a mean value, the related uncertainty, and an upper and lower bound of the percolation fraction. The algorithm proved able to infer this 3D property from 2D information of the metallic fuel with confidence intervals, thus establishing a path to infer 3D properties directly from 2D experimental images. The knowledge of such a relationship can be used to extrapolate the percolation threshold with confidence interval, which is a crucial property in defining microstructure-based fission gas release models of metallic fuels.
Presentations:
"Current Status of Postirradiation Examination of the AFC Metallic Fuel" Jason Harp, Luca Capriotti, Fabiola Cappia, Steven Hayes, ANS Annual Meeting 2018 June 18-22, (2018)
"Electron microscopy characterization of fast reactor MOX joint-oxide-gaine (JOG)" Fabiola Cappia, Brandon Miller, Daniel Murray, Lingfeng He, Brian Frickey, John Stanek, Jason Harp, EMRS 2019 May 27-31, (2019)
"Image analysis and computer vision: a tool for investigating irradiated fuel microstructure" Fabiola Cappia, NUMAT 2018 October 15-18, (2018)
"Post-irradiation Examinations of Annular Mixed Oxide Fuels" Fabiola Cappia, Jason Harp, Kosuke Tanaka, Masato Kato, Kenneth McClellan, Global 2019 September 22-26, (2019)
NSUF Articles:
DOE Awards 33 Rapid Turnaround Experiment Research Proposals - Projects total approximately $1.2 million These projects will continue to advance the understanding of irradiation effects in nuclear fuels and materials in support of the mission of the DOE Office of Nuclear Energy. Monday, June 18, 2018 - Calls and Awards
Department of Energy Nuclear Science User Facilities Awards 29 Rapid Turnaround Experiment Proposals - Awarded projects total nearly $1.14M in access awards Tuesday, June 8, 2021 - News Release, Calls and Awards

About Us

The Nuclear Science User Facilities (NSUF) is the U.S. Department of Energy Office of Nuclear Energy's only designated nuclear energy user facility. Through peer-reviewed proposal processes, the NSUF provides researchers access to neutron, ion, and gamma irradiations, post-irradiation examination and beamline capabilities at Idaho National Laboratory and a diverse mix of university, national laboratory and industry partner institutions.

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