Takaaki Koyanagi

Profile Information
Name
Dr. Takaaki Koyanagi
Institution
Oak Ridge National Laboratory
Position
Research associate
h-Index
ORCID
0000-0001-7272-4049
Expertise
Ceramics, Neutron Irradiation
Publications:
"ACCELERATED IRRADIATION TESTING OF MINIATURE NUCLEAR FUEL AND CLADDING SPECIMENS" Christian Petrie, Takaaki Koyanagi, Richard Howard, Kevin Field, Joseph Burns, Kurt Terrani, OSTI.govI Vol. 2018 Link
"Advanced synchrotron characterization techniques for fusion materials science" David Sprouster, J Trelewicz, Lance Snead, Daniel Morrall, Takaaki Koyanagi, X Hu, Chad Parish, Lizhen Tan, Yutai Katoh, Brian Wirth, Journal of Nuclear Materials Vol. 543 2020 152574 Link
"Ceramic composites: A review of toughening mechanisms and demonstration of micropillar compression for interface property extraction" Christian Deck, Peter Hosemann, Yutai Katoh, Yevhen Zayachuk, Joey Kabel, David Armstrong, Takaaki Koyanagi, Journal of Materials Research Vol. 33 2018 424-439 Link
Ceramic fiber–matrix composites (CFMCs) are exciting materials for engineering applications in extreme environments. By integrating ceramic fibers within a ceramic matrix, CFMCs allow an intrinsically brittle material to exhibit sufficient structural toughness for use in gas turbines and nuclear reactors. Chemical stability under high temperature and irradiation coupled with high specific strength make these materials unique and increasingly popular in extreme settings. This paper first offers a review of the importance and growing body of research on fiber–matrix interfaces as they relate to composite toughening mechanisms. Second, micropillar compression is explored experimentally as a high-fidelity method for extracting interface properties compared with traditional fiber push-out testing. Three significant interface properties that govern composite toughening were extracted. For a 50-nm-pyrolytic carbon interface, the following were observed: a fracture energy release rate of ~2.5 J/m2, an internal friction coefficient of 0.25 ± 0.04, and a debond shear strength of 266 ± 24 MPa. This research supports micromechanical evaluations as a unique bridge between theoretical physics models for microcrack propagation and empirically driven finite element models for bulk CFMCs.
"Dimensional stability and anisotropy of SiC and SiC-based composites in transition swelling regime" Yutai Katoh, Takaaki Koyanagi, Lance Snead, Joel McDuffee, Ken Yueh, Journal of Nuclear Materials Vol. 499 2017 471-479 Link
Swelling, or volumetric expansion, is an inevitable consequence of the atomic displacement damage in crystalline silicon carbide (SiC) caused by energetic neutron irradiation. Because of its steep temperature and dose dependence, understanding swelling is essential for designing SiC-based components for nuclear applications. In this study, swelling behaviors of monolithic CVD SiC and nuclear grade SiC fiber – SiC matrix (SiC/SiC) composites were accurately determined, supported by the irradiation temperature determination for individual samples, following neutron irradiation within the lower transition swelling temperature regime. Slightly anisotropic swelling behaviors were found for the SiC/SiC samples and attributed primarily to the combined effects of the pre-existing microcracking, fiber architecture, and specimen dimension. A semi-empirical model of SiC swelling was calibrated and presented. Finally, implications of the refined model to selected swelling-related issues for SiC-based nuclar reactor components are discussed.
"Equilibrium shapes and surface selection of nanostructures in 6H-SiC" Yutai Katoh, Takaaki Koyanagi, Chad Parish, Sosuke Kondo, Applied Physics Letters Vol. 110 2017 Link
The equilibrium shape of 6H-SiC nanostructures and their surfaces were studied by analyzing nano-void (10 nm) shapes, which were introduced in monocrystalline 6H-SiC by hightemperature neutron irradiation, using transmission electron microscopy. The nano-voids were determined to be irregular icosahedrons truncated with six {1100}, twelve f1103}, one smaller top-basal, and one larger bottom-basal planes, which suggests that {1100} and f1103} are the next stable surface class after the basal planes. The relatively frequent absence of the {1100} surface in the nano-voids indicated that the (1103Þ surface type is energetically rather stable. These non-basal surfaces were found not to be atomically flat due to the creation of nanofacets with half unit-cell height in the c-axis. The {1100} and f1103} surfaces were classified as two and four face types according to their possible nanofacets and surface termination, respectively. We also discuss the surface energy difference between the (1103) and (1103) face types in relation to the energy balance within the equilibrium, but irregular, polyhedron, in which the (1103) surface had double the surface energy of the (1103Þ surface (3900 erg/cm2)
"Evaluating the Irradiation Effects on the Elastic Properties of Miniature Monolithic SiC Tubular Specimens" Yutai Katoh, Christian Petrie, Kurt Terrani, Gyanender Singh, Takaaki Koyanagi, Journal of Nuclear Materials Vol. 499 2018 107-110 Link
The initial results of a post-irradiation examination study conducted on CVD SiC tubular specimens irradiated under a high radial heat flux are presented herein. The elastic moduli were found to decrease more than that estimated based on previous studies. The significant decreases in modulus are attributed to the cracks present in the specimens. The stresses in the specimens, calculated through finite element analyses, were found to be greater than the expected strength of irradiated specimens, indicating that the irradiation-induced stresses caused these cracks. The optical microscopy images and predicted stress distributions indicate that the cracks initiated at the inner surface and propagated outward.
"Evaluation of Irradiation-Induced Strain in SiC Tubes by a Combination of Experiment and Simulation" Takaaki Koyanagi, Yutai Katoh, Christian Petrie, Kurt Terrani, Transactions of the American Nuclear Society Vol. 118 2018 Link
"Experimental design and analysis for irradiation of SiC/SiC composite tubes under a prototypic high heat flux" Christian Deck, Yutai Katoh, Takaaki Koyanagi, Christian Petrie, Joel McDuffee, Kurt Terrani, Journal of Nuclear Materials Vol. 491 2017 94-104 Link
The purpose of this work is to design an irradiation vehicle for testing silicon carbide (SiC) fiber-reinforced SiC matrix composite cladding materials under conditions representative of a light water reactor in order to validate thermo-mechanical models of stress states in these materials due to irradiation swelling and differential thermal expansion. The design allows for a constant tube outer surface temperature in the range of 300–350 °C under a representative high heat flux (~0.66 MW/m2) during one cycle of irradiation in an un-instrumented “rabbit” capsule in the High Flux Isotope Reactor. An engineered aluminum foil was developed to absorb the expansion of the cladding tubes, due to irradiation swelling, without changing the thermal resistance of the gap between the cladding and irradiation capsule. Finite-element analyses of the capsule were performed, and the models used to calculate thermal contact resistance were validated by out-of-pile testing and post-irradiation examination of the foils and passive SiC thermometry. Six irradiated cladding tubes (both monoliths and composites) were irradiated and subsequently disassembled in a hot cell. The calculated temperatures of passive SiC thermometry inside the capsules showed good agreement with temperatures measured post-irradiation, with two calculated temperatures falling within 10 °C of experimental measurements. The success of this design could lead to new opportunities for irradiation applications with materials that suffer from irradiation swelling, creep, or other dimensional changes that can affect the specimen temperature during irradiation.
"Fully Ceramic Microencapsulated fuel in prismatic high-temperature gas-cooled reactors: Sensitivity of reactor behavior during design basis accidents to fuel properties and the potential impact of the SiC defect annealing process" Takaaki Koyanagi, Yutai Katoh, Kurt Terrani, Nicholas Brown, Nuclear Engineering and Design Vol. 345 2019 125-147 Link
"Irradiation resistance of silicon carbide joint at light water reactor–relevant temperature" Yutai Katoh, Takaaki Koyanagi, James Kiggans, Tatsuya Hinoki, Hesham Khalifa, Christian Deck, Christina Back, Journal of Nuclear Materials Vol. 488 2017 150-159 Link
Monolithic silicon carbide (SiC) to SiC plate joints were fabricated and irradiated with neutrons at 270–310 °C to 8.7 dpa for SiC. The joining methods included solid state diffusion bonding using titanium and molybdenum interlayers, SiC nanopowder sintering, reaction sintering with a Ti-Si-C system, and hybrid processing of polymer pyrolysis and chemical vapor infiltration (CVI). All the irradiated joints exhibited apparent shear strength of more than 84 MPa on average. Significant irradiation-induced cracking was found in the bonding layers of the Ti and Mo diffusion bonds and Ti-Si-C reaction sintered bond. The SiC-based bonding layers of the SiC nanopowder sintered and hybrid polymer pyrolysis and CVI joints all showed stable microstructure following the irradiation.
"Irradiation-induced ß to a SiC transformation at low temperature" Yutai Katoh, Takaaki Koyanagi, Chad Parish, Sosuke Kondo, Scientific Reports Vol. 7 2017 Link
We observed that ß-SiC, neutron irradiated to 9?dpa (displacements per atom) at ˜1440?°C, began transforming to a-SiC, with radiation-induced Frank dislocation loops serving as the apparent nucleation sites. 1440?°C is a far lower temperature than usual ß???a phase transformations in SiC. SiC is considered for applications in advanced nuclear systems, as well as for electronic or spintronic applications requiring ion irradiation processing. ß-SiC, preferred for nuclear applications, is metastable and undergoes a phase transformation at high temperatures (typically 2000?°C and above). Nuclear reactor concepts are not expected to reach the very high temperatures for thermal transformation. However, our results indicate incipient ß???a phase transformation, in the form of small (~5–10?nm) pockets of a-SiC forming in the ß matrix. In service transformation could degrade structural stability and fuel integrity for SiC-based materials operated in this regime. However, engineering this transformation deliberately using ion irradiation could enable new electronic applications.
"Mechanical properties of SiC composites neutron irradiated under light water reactor relevant temperature and dose conditions" Yutai Katoh, Takaaki Koyanagi, Journal of Nuclear Materials Vol. 494 2017 46-54 Link
Silicon carbide (SiC) fiber–reinforced SiC matrix (SiC/SiC) composites are being actively investigated for use in accident-tolerant core structures of light water reactors (LWRs). Owing to the limited number of irradiation studies previously conducted at LWR-coolant temperature, this study examined SiC/SiC composites following neutron irradiation at 230–340 °C to 2.0 and 11.8 dpa in the High Flux Isotope Reactor. The investigated materials were chemical vapor infiltrated (CVI) SiC/SiC composites with three different reinforcement fibers. The fiber materials were monolayer pyrolytic carbon (PyC) -coated Hi-Nicalon™ Type-S (HNS), Tyranno™ SA3 (SA3), and SCS-Ultra™ (SCS) SiC fibers. The irradiation resistance of these composites was investigated based on flexural behavior, dynamic Young's modulus, swelling, and microstructures. There was no notable mechanical properties degradation of the irradiated HNS and SA3 SiC/SiC composites except for reduction of the Young's moduli by up to 18%. The microstructural stability of these composites supported the absence of degradation. In addition, no progressive swelling from 2.0 to 11.8 dpa was confirmed for these composites. On the other hand, the SCS composite showed significant mechanical degradation associated with cracking within the fiber. This study determined that SiC/SiC composites with HNS or SA3 SiC/SiC fibers, a PyC interphase, and a CVI SiC matrix retain their properties beyond the lifetime dose for LWR fuel cladding at the relevant temperature.
"Micro-mechanical evaluation of SiC-SiC composite interphase properties and debond mechanisms" Mehdi Balooch, Peter Hosemann, Cameron Howard, Yutai Katoh, Takaaki Koyanagi, Yong Yang, Joey Kabel, Kurt Terrani, Composites Part B: Engineering Vol. 131 2017 173-183 Link
SiC-SiC composites exhibit exceptional high temperature strength and oxidation properties making them an advantageous choice for accident tolerant nuclear fuel cladding. In the present work, small scale mechanical testing along with AFM and TEM analysis were employed to evaluate PyC interphase properties that play a key role in the overall mechanical behavior of the composite. The Mohr-Coulomb formulation allowed for the extraction of the internal friction coefficient and debonding shear strength as a function of the PyC layer thickness, an additional parameter. These results have led to re-evaluation of the Mohr-Coulomb failure criterion and adjustment via a new phenomenological equation.SiC-SiC composites exhibit exceptional high temperature strength and oxidation properties making them an advantageous choice for accident tolerant nuclear fuel cladding. In the present work, small scale mechanical testing along with AFM and TEM analysis were employed to evaluate PyC interphase properties that play a key role in the overall mechanical behavior of the composite. The Mohr-Coulomb formulation allowed for the extraction of the internal friction coefficient and debonding shear strength as a function of the PyC layer thickness, an additional parameter. These results have led to re-evaluation of the Mohr-Coulomb failure criterion and adjustment via a new phenomenological equation.
"Microstructural evolution of pure tungsten neutron irradiated with a mixed energy spectrum" Lauren Garrison, Yutai Katoh, Takaaki Koyanagi, Lance Snead, Kiran Kumar, Taehyun Hwang, Xunxiang Hu, Journal of Nuclear Materials Vol. 490 2017 66-74 Link
Microstructures of single-crystal bulk tungsten (W) and polycrystalline W foil with a strong grain texture were investigated using transmission electron microscopy following neutron irradiation at ∼90–800 °C to 0.03–4.6 displacements per atom (dpa) in the High Flux Isotope Reactor with a mixed energy spectrum. The dominant irradiation defects were dislocation loops and small clusters at ∼90 °C. Additional voids were formed in W irradiated at above 460 °C. Voids and precipitates involving transmutation rhenium and osmium were the dominant defects at more than ∼1 dpa. We found a new phenomenon of microstructural evolution in irradiated polycrystalline W: Re- and Os-rich precipitation along grain boundaries. Comparison of results between this study and previous studies using different irradiation facilities revealed that the microstructural evolution of pure W is highly dependent on the neutron energy spectrum in addition to the irradiation temperature and dose.
"Microstructure and hydrothermal corrosion behavior of NITE-SiC with various sintering additives in LWR coolant environments" Yutai Katoh, Takaaki Koyanagi, Chad Parish, Journal of the European Ceramic Society Vol. 37 2017 1261-1279 Link
"Quantification of irradiation defects in beta-silicon carbide using Raman spectroscopy" Yutai Katoh, Takaaki Koyanagi, Michael Lance, Scripta Materialia Vol. 125 2016 58-62 Link
Raman spectra from polycrystalline beta-silicon carbide (SiC) were collected following neutron irradiation at 380–1180 °C to 0.011–1.87 displacement per atom. The longitudinal optical (LO) peak shifted to a lower frequency and broadened as a result of the irradiation. The changes observed in the LO phonon line shape and position in neutron-irradiated SiC are explained by a combination of changes in the lattice constant and Young's modulus, and the phonon confinement effect. The phonon confinement model reasonably estimates the defect-defect distance in the irradiated SiC, which is consistent with results from previous experimental studies and simulations.
"Raman spectroscopy of neutron irradiated silicon carbide: Correlation among Raman spectra, swelling, and irradiation temperature" Takaaki Koyanagi, Yutai Katoh, Michael Lance, Journal of Raman Spectroscopy Vol. 49 2018 1686-1692 Link
"X-ray characterization of anisotropic defect formation in SiC under irradiation with applied stress" David Sprouster, Takaaki Koyanagi, Lance Snead, Yutai Katoh, Scripta Materialia Vol. 197 2021 113785 Link
"X-ray characterization of anisotropic defect formation in SiC under irradiation with applied stress" David Sprouster, Takaaki Koyanagi, Lance Snead, Yutai Katoh, Scripta Materialia Vol. 197 2021 113785 Link
Presentations:
"Assessment of Pre-irradiation SiC CMC Joint Performance in Representative Cladding Geometries" Christian Deck, Sean Gonderman, George Jacobsen, Takaaki Koyanagi, Christian Petrie, Global/TopFuel 2019 September 22-26, (2019) Link
"Evaluation of Elastic Properties of SiC-SiC Tubular Specimens Using Resonant Ultrasound Spectroscopy" Yutai Katoh, Takaaki Koyanagi, Christian Petrie, 42nd International Conference and Expo on Advanced Ceramics and Composites (2018) January 21-27, (2018)
"Evaluation of Irradiation-Induced Strain in SiC Tubes by a Combination of Experiment and Simulation" Takaaki Koyanagi, Yutai Katoh, Gyanender Singh, Xunxiang Hu, Christian Petrie, Kurt Terrani, 2018 ANS Annual Meeting NFSM Poster Session June 17-21, (2018) Link
"Irradiation and PIE of ATF cladding materials in HFIR" Kevin Field, Yutai Katoh, Takaaki Koyanagi, Christian Petrie, Advanced Fuels Campaign Integration Meeting (2017) March 1-2, (2017)
"Post Irradiation Examination of SiC Tube Subjected to Simultaneous Irradiation and Radial High Heat Flux" Christian Deck, Yutai Katoh, Takaaki Koyanagi, Christian Petrie, 2017 ANS Annual Meeting [unknown]
"Post-irradiation examination of SiC tubes neutron irradiated under a radial high heat flux" Christian Deck, Yutai Katoh, Takaaki Koyanagi, Christian Petrie, 42nd International Conference and Expo on Advanced Ceramics and Composites (2018) January 21-26, (2018)
"Post-Irradiation Validation of High Heat Flux SiC/SiC Cladding Irradiation Design" Yutai Katoh, Takaaki Koyanagi, Christian Petrie, the 41st International Conference and Expo on Advanced Ceramics and Composites January 22-27, (2017)
"Transient Swelling of SiC/SiC Composites and its Implications to Fuels and Core Designs" Yutai Katoh, Takaaki Koyanagi, TMS 2018 March 12-15, (2018)
NSUF Articles:
U.S. Department of Energy Announces FY17 CINR FOA Awards - DOE selected 14 NSUF projects DOE selected five university, four national laboratory, and five industry-led projects that will take advantage of NSUF capabilities to investigate important nuclear fuel and material applications. Wednesday, September 20, 2017 - Calls and Awards
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
DOE awards 39 RTE Projects - Projects total approximately $1.3 million Thursday, February 1, 2018 - Calls and Awards
2020 NSUF Annual Review - Presentations The 2020 NSUF Annual Review presentations are now available online Tuesday, December 15, 2020 - DOE, Annual Review, Presentations