Jason Harp

Publications:

		"Bubble morphology in U3Si2 implanted by high-energy Xe ions at 300ºC" Yinbin Miao, Jason Harp, Kun Mo, Shaofei Zhu, Tiankai Yao, Jie Lian, Abdellatif Yacout, Journal of Nuclear Materials Vol. 495 2017 146-153 Link The microstructure modifications of a high-energy Xe implanted U3Si2, a promising accident tolerant fuel candidate, were characterized and are reported upon. The U3Si2 pellet was irradiated at Argonne Tandem Linac Accelerator System (ATLAS) by an 84 MeV Xe ion beam at 300 °C. The irradiated specimen was then investigated using a series of transmission electron microscopy (TEM) techniques. A dense distribution of bubbles were observed near the range of the 84 MeV Xe ions. Xe gas was also found to accumulate at multiple types of sinks, such as dislocations and grain boundaries. Bubbles aggregated at those sinks are slightly larger than intragranular bubbles in lattice. At 300 °C, the gaseous swelling strain is limited as all the bubbles are below 10 nm, implying the promising fission gas behavior of U3Si2 under normal operating conditions in light water reactors (LWRs).
		"Characterization of solid fission products in 13.7% FIMA MOX fuel using electron microscopy techniques" Riley Parrish, Karen Wright, Alexander Winston, Jason Harp, Casey McKinney, Assel Aitkaliyeva, Journal of Nuclear Materials Vol. 524 2019 67-79 Link This work utilizes electron microscopy-based techniques to examine the radial behavior of solid fission products in plutonium (Pu) bearing mixed oxide (MOX) fuel irradiated to a burnup of 13.7% fissions per initial metal atom (FIMA). Metallic precipitates primarily consist of five fission products: ruthenium (Ru), rhodium (Rh), technetium (Tc), molybdenum (Mo), and palladium (Pd). The five metal precipitates (FMPs) examined in this work have low concentrations of Pd and Mo, with no major compositional differences along the fuel radius. A secondary Pd–Te metallic phase forms in cooler regions of the pellet, likely due to the diffusion of gaseous species away from the central void. X-ray chemical maps indicate that the Pd–Te phase can nucleate on the surface of FMPs before precipitating into separate particles. These particles were also found to alloy with iron (Fe) near the surface of the fuel pellet due to interdiffusion with the stainless-steel cladding. The insoluble perovskite oxide phase was found to form near the central void and at intermediate radial positions, but not at the fuel edge. These findings suggest that solid fission product phases form at varying counts and compositions along the fuel pellet radius, and thus should be considered when describing the thermal behavior of the fuel.
		"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.
		"Fuel-cladding chemical interaction of a prototype annular U-10Zr fuel with Fe-12Cr ferritic/martensitic HT-9 cladding" Xiang Liu, Luca Capriotti, Tiankai Yao, Jason Harp, Michael Benson, Yachun Wang, Fei Teng, Lingfeng He, https://www.sciencedirect.com/science/article/pii/S002231152031196X#ack0001 Vol. 544 2021 Link
		"Hydrothermal synthesis of silicon oxide clad uranium oxide nanowires" Lingfeng He, Jason Harp, Adrian Wagner, Rita Hoggan, Kevin Tolman, Journal of the American Cermic Society Vol. 2018 1004-1008 Link
		"In situ TEM Ion Irradiation Investigations on U3Si2 at LWR Temperatures" Jason Harp, Yinbin Miao, Kun Mo, Sumit Bhattacharya, Peter Baldo, Abdellatif Yacout, Journal of Nuclear Materials Vol. 484 2017 168-173 Link The radiation-induced amorphization of U3Si2 was investigated by in-situ transmission electron microscopy using 1 MeV Kr ion irradiation. Both arc-melted and sintered U3Si2 specimens were irradiated at room temperature to confirm the similarity in their responses to radiation. The sintered specimens were then irradiated at 350 °C and 550 °C up to 7.2 × 1015 ions/cm2 to examine their amorphization behavior under light water reactor (LWR) conditions. U3Si2 remains crystalline under irradiation at LWR temperatures. Oxidation of the material was observed at high irradiation doses.
		"In-situ TEM study of the ion irradiation behavior of U3Si2 and U3Si5" Tiankai Yao, Bowen Gong, Yinbin Miao, Jason Harp, Jie Lian, Journal of Nuclear Materials Vol. 511 2018 56-63 Link U3Si2 and U3Si5 are two important uranium silicide phases currently under extensive investigation as potential fuel forms or components for light water reactors (LWRs) to enhance accident tolerance. In this paper, their irradiation behaviors are studied by ion beam irradiations with various ion mass and energies, and their microstructure evolution is investigated by in-situ transmission electron microscopy (TEM). U3Si2 can easily be amorphized by ion beam irradiations (by 1 MeV Ar2+ or Kr2+) at room temperature with the critical amorphization dose less than 1 dpa. The critical amorphization temperatures of U3Si2 irradiated by 1 MeV Kr2+ and 1 MeV Ar2+ ion are determined as 580 ± 10 K and 540 ± 5 K, respectively. In contrast, U3Si5 remains crystalline up to 8 dpa at room temperature and is stable against ion irradiation-induced amorphization up to ∼50 dpa by either 1 MeV Kr2+ or 150 KeV Kr+ at 623 K. These results provide valuable experimental data to guide future irradiation experiments, support the relevant post irradiation examination, and serve as the experimental basis for the validation of advanced fuel performance models.
		"Microstructure investigations of U3Si2 implanted by high-energy Xe ions at 600°C" Yinbin Miao, Jason Harp, Kun Mo, Yeon Soo Kim, Shaofei Zhu, Abdellatif Yacout, Journal of Nuclear Materials Vol. 503 2018 314-322 Link The microstructure investigations on a high-energy Xe-implanted U3Si2 pellet were performed. The promising accident tolerant fuel (ATF) candidate, U3Si2, was irradiated by 84?MeV Xe ions at 600?°C at Argonne Tandem Linac Accelerator System (ATLAS). The characterizations of the Xe implanted sample were conducted using advanced transmission electron microscopy (TEM) techniques. An oxidation layer was observed on the sample surface after irradiation under the 10-5?Pa vacuum. The study on the oxidation layer not only unveils the readily oxidation behavior of U3Si2 under high-temperature irradiation conditions, but also develops an understanding of its oxidation mechanism. Intragranular Xe bubbles with bimodal size distribution were observed within the Xe deposition region of the sample induced by 84?MeV Xe ion implantation. At the irradiation temperature of 600?°C, the gaseous swelling strain contributed by intragranular bubbles was found to be insignificant, indicating an acceptable fission gas behavior of U3Si2 as a light water reactor (LWR) fuel operating at such a temperature.
		"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.
		"Radial microstructural evolution in low burnup fast reactor MOX fuel" Jason Harp, Journal of Nuclear Materials Vol. 523 2019 182-188 Link Examination of irradiated fast reactor mixed-oxide (MOX) fuel was conducted to analyze microstructural behavior and defect evolution as a function of radial position. The fuel analyzed in this work was irradiated to 3.4% fissions per initial metal atom (FIMA) in the Fast Flux Test Facility. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to analyze microstructural features and fission product secondary phases. A dual-beam focused ion beam (FIB)/SEM was used to prepare several samples along the fuel radius for transmission electron microscopy (TEM) defect analysis. The microstructure near the center of the fuel pellet showed separated grain boundaries accompanied by fission gas bubbles. The fuel pellet did not reach the threshold linear heating rate (LHR) needed for restructuring, formation of the columnar or equiaxed regions was not observed. Metallic fission products aggregated in pores along grain boundaries near the pellet center, but no metallic precipitates were visible in the outer region. Moreover, no appreciable amount of insoluble perovskite phase was formed. The dislocation loop density is highest near the fuel central void but decreases past the mid-point of the fuel radius likely due to the self-irradiation effects. Dislocation lines follow an inverse trend, with the lower density observed near the hottest regions and increasing in the pellet outer radius. These results indicate that the thermal gradient in MOX fuels heavily influences the localized fission product morphology and defect behavior.
		"Radiation-induced grain subdivision and bubble formation in U3Si2 at LWR temperature" Bowen Gong, Jason Harp, Jie Lian, Tiankai Yao, Lingfeng He, Michael Tonks, Journal of Nuclear Materials Vol. 498 2017 169-175 Link U3Si2, an advanced fuel form proposed for light water reactors (LWRs), has excellent thermal conductivity and a high fissile element density. However, limited understanding of the radiation performance and fission gas behavior of U3Si2 is available at LWR conditions. This study explores the irradiation behavior of U3Si2 by 300 keV Xe+ ion beam bombardment combining with in-situ transmission electron microscopy (TEM) observation. The crystal structure of U3Si2 is stable against radiation-induced amorphization at 350 °C even up to a very high dose of 64 displacements per atom (dpa). Grain subdivision of U3Si2 occurs at a relatively low dose of 0.8 dpa and continues to above 48 dpa, leading to the formation of high-density nanoparticles. Nano-sized Xe gas bubbles prevail at a dose of 24 dpa, and Xe bubble coalescence was identified with the increase of irradiation dose. The volumetric swelling resulting from Xe gas bubble formation and coalescence was estimated with respect to radiation dose, and a 2.2% volumetric swelling was observed for U3Si2 irradiated at 64 dpa. Due to extremely high susceptibility to oxidation, the nano-sized U3Si2 grains upon radiation-induced grain subdivision were oxidized to nanocrystalline UO2 in a high vacuum chamber for TEM observation, eventually leading to the formation of UO2 nanocrystallites stable up to 80 dpa.

Presentations:

	"Advanced Characterization of Irradiated UO2 Fuel" Lingfeng He, Michael Moorehead, Brandon Miller, Jason Harp, Xianming Bai, TMS 2018 March 11-15, (2018)
	"Assessment of irradiation damage and chemical interactions in neutron irradiated U-10Zr fuel and HT9 cladding with high-energy X-rays" Jonova Thomas, Sri Tapaswi Nori, Alejandro Figueroa, Ran Ren, Peter Kenesei, Jon D. Almer, Jason Harp, Maria Okuniewski, MRS Fall Meeting November 26-1, (2017)
	"Assessment of Radiation Damage and Microstructural Changes in Neutron Irradiated U-10Zr Fuels with High Energy X-Rays" Jonova Thomas, Sri Tapaswi Nori, Alejandro Figueroa, Maria Okuniewski, Peter Kenesei, Jun-Sang Park, Jon Almer, Jason Harp, ANS Conference on Embedded Topical Nuclear Fuels & Structural Materials for Next Generation Nuclear Reactors June 17-21, (2018)
	"Chemical and microstructural analysis of irradiated mixed oxide fuels" Assel Aitkaliyeva, Riley Parrish, Jason Harp, The Minerals, Metals and Materials Society (TMS) Annual Meeting & Exhibition March 11-15, (2018)
	"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)
	"Microstructural analysis of irradiated mixed oxide fuels" Riley Parrish, Assel Aitkaliyeva, Jason Harp, NuMat 2018 October 14-18, (2018)
	"Microstructural characterization of radiation damage in neutron irradiated U-10wt%Zr fuels" Jonova Thomas, Sri Tapaswi Nori, Alejandro Figueroa, Maria Okuniewski, Peter Kenesei, Jun Sang Park, Jason Harp, NuMat: The Nuclear materials Conference October 14-18, (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)
	"Preliminary postirradiation examination of several EBR-II metallic fuel pins" Luca Capriotti, Jason Harp, Daniel Wachs, Steven Hayes, NUMAT 2018 October 15-18, (2018)
	"TEM Analysis of Irradiated Mixed-oxide Fuel" Assel Aitkaliyeva, Riley Parrish, Jason Harp, American Nuclear Society Student Conference 2018 April 5-7, (2018)

NSUF Articles:

DOE-NE Awards 19 RTE Projects - New projects total approximately $690K Thursday, February 6, 2020 - Announcement, Calls and Awards, Newsletter, News Release

Accomplishments

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Authored 10+ NSUF-supported publications

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Awarded 3+ RTE Proposals

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Reviewed 10+ RTE Proposals

NSUF Supported Research

High Temperature Testing of Fully Ceramic Microencapsulated Fuel - FY 2024 RTE 2nd Call, #4962

Pulsed Neutron Characterization of U-1Pd-10Zr Irradiated Fuel - FY 2020 RTE 1st Call, #2958

Study of the Irradiation Behavior of Fast Reactor Mixed Oxide Annular Fuel with Modern Microstructural Characterization to Support Science Based Model Validation - FY 2017 CINR, #3053

NSUF Research Collaborations

Atom probe tomography study of the fuel cladding chemical interaction (FCCI) layer in irradiated U-10Zr fuel with HT-9 cladding - FY 2019 RTE 1st Call, #1635

Compositional and Defect Analysis of the FCCI in high burnup UO2 - FY 2023 RTE 1st Call, #4537

Electron microscopy characterization of fast reactor MOX joint oxyde-gaine (JOG) - FY 2018 RTE 3rd Call, #1538

EPMA Characterization of Actinide Redistribution and Fission Product Composition in MOX Fuels - FY 2018 RTE 2nd Call, #1484

Fission Gas Behavior and Fuel Swelling of Accident Tolerant U3Si2 Fuels by Ion Beam Irradiation - FY 2017 RTE 2nd Call, #957

High temperature in-situ small-scale mechanical testing of fast reactor mixed oxide (MOX) pins. - FY 2018 RTE 2nd Call, #1452

In-situ high temperature Transmission Electron Microscopy (TEM) of radiogenic He in high burnup fast reactor MOX - FY 2018 RTE 3rd Call, #1553

In-situ separate effect studies of thermal and radiation effects on Xe diffusion in alpha-U and U-10Zr. - FY 2019 RTE 1st Call, #1621

In-situ small-scale mechanical testing of fast reactor advance metallic fuel alloy. - FY 2019 RTE 1st Call, #1680

Investigation of fuel-cladding chemical interaction (FCCI) in irradiated U-Pu-Zr fuel - FY 2018 RTE 3rd Call, #1533

Irradiation and TEM Characterization of induced Defects in a-U and d-UZr2+x Crystals - FY 2019 RTE 2nd Call, #1784

Isotope density mapping using Energy Resolved Neutron Resonance Imaging of a High Burnup UO2 Fuel Fragment - FY 2023 RTE 1st Call, #4584

Microstructural characterization of ~7% burn-up MOX fuel - FY 2018 RTE 1st Call, #1179

Microstructural characterization of 13% burn-up MOX fuel - FY 2017 RTE 3rd Call, #1042

Microstructural characterization of 21% burn-up MOX fuel - FY 2017 RTE 3rd Call, #1043

Microstructural characterization of 23% burn-up MOX fuel - FY 2017 RTE 1st Call, #812

Microstructural characterization of 3% burn-up MOX fuel - FY 2017 RTE 2nd Call, #909

Microstructural characterization of transmutation nitride fuels for fast reactors - FY 2018 RTE 2nd Call, #1428

Microstructural Phase Characterization of Irradiated and Control U-10Zr Fuels - FY 2018 RTE 1st Call, #1243

Nanoindentation of Phases in Irradiated and Control U-10Zr Fuels - FY 2019 RTE 1st Call, #1666

Pre-oxidation effect on ATF cladding performance by characterization of irradiated FeCrAl-UO2 capsules - FY 2021 RTE 1st Call, #4269

Radiation Response and Microstructure of Accident Tolerant U3Si2 Fuels by Ion Beam Irradiation - FY 2017 RTE 1st Call, #835