NSUF - Nuclear Science User Facilities

Tyler Gerczak

Profile Information
Name
Dr. Tyler Gerczak
Institution
Oak Ridge National Laboratory
Position
Dr.
h-Index
ORCID
0000-0001-9967-3579
Expertise
PIE, TRi-structural ISOtropic (TRISO) Particle Fuel
Publications:
"A Challenge to Multivariate Statistical Analysis: Spent Nuclear Fuel" Philip Edmondson, Tyler Gerczak, Chad Parish, Kurt Terrani, Microscopy & Microanalysis Vol. 22 2016 Link
"Assembly of Rabbit Capsules for Irradiation of Pyrolytic Carbon / Silicon Carbide Diffusion Couples in the High Flux Isotope Reactor" Kory Linton, Tyler Gerczak, Kurt Terrani, Christian Petrie, OSTI.gov, Technical Report Vol. 2018 Link
Tristructural-isotropic (TRISO)–coated particle fuel is a promising advanced fuel concept being considered for several advanced reactor applications and for accident-tolerant fuel for light water reactors. One of the aspects studied in the development of this advanced fuel concept is the release of specific fission products (Ag, Eu, and Sr). The silicon carbide (SiC) layer of TRISO fuel serves as the primary barrier to metallic fission products and actinides not retained in the fuel kernel. The goal of this project is to evaluate the effect of irradiation on the diffusion of these fission products in the SiC layer of the fuel. For this purpose, rabbit capsules containing small slab diffusion couple specimens have been assembled to be irradiated in the High Flux Isotope Reactor (HFIR). The diffusion couple specimens have been fabricated using similar processes and equipment as those used to make TRISO particles; the desired fission products have been implanted in the specimens using an ion accelerator. Moreover, the effect of temperature on the fission products diffusion will be studied separately by performing thermal experiments in the absence of irradiation. This report describes the irradiation experiment design concept, summarizes the irradiation test matrix, and reports on the successful assembly of two rabbit capsules that will be irradiated in the HFIR.
"Cesium and Silver Diffusion in SiC for TRISO Applications" Todd Allen, Tyler Gerczak, Zihua Zhu, Transactions of the American Nuclear Society Vol. 104 2011 47-48 Link
"Development of planar PyC/SiC diffusion couples to investigate irradiation effects and microstructural variation on fission product diffusion" Tyler Gerczak, John Hunn, Brian Jolly, Austin Schumacher, Anne Campbell, John Dyer, Xunxiang Hu, Proceedings of HTR 2018 Vol. 2018 0047
"Development of planar PyC/SiC diffusion couples to investigate irradiation effects and microstructural variation on fission product diffusion" Tyler Gerczak, John Hunn, Brian Jolly, Austin Schumacher, Anne Campbell, John Dyer, Xunxiang Hu, Proceedings of HTR 2018 Vol. 2018 Link
"Diffusion of fissile inventory in AGR-1 Triso fuel particles as a function of temperature & silver retention" Rachel Seibert, Jeff Terry, Tyler Gerczak, Kurt Terrani, John Hunn, Fred Montgomery, Charles Baldwin, Transactions of the American Nuclear Society Vol. 118 2018 1486-1487 Link
"Effect of carbon ion irradiation on Ag diffusion in SiC" Tyler Gerczak, bin leng, Kumar Sridharan, Izabela Szlufarska, Hyunseok Ko, Jie Deng, Andrew Giordani, Jerry Hunter, Dane Morgan, Journal of Nuclear Materials Vol. 471 2017 220-232 Link
Transport of Ag fission product through the silicon-carbide (SiC) diffusion barrier layer in TRISO fuel particles is of considerable interest given the application of this fuel type in high temperature gas-cooled reactor (HTGR) and other future reactor concepts. The reactor experiments indicate that radiation may play an important role in release of Ag; however so far the isolated effect of radiation on Ag diffusion has not been investigated in controlled laboratory experiments. In this study, we investigate the diffusion couples of Ag and polycrystalline 3C–SiC, as well as Ag and single crystalline 4H–SiC samples before and after irradiation with C2+ ions. The diffusion couple samples were exposed to temperatures of 1500 °C, 1535 °C, and 1569 °C, and the ensuing diffusion profiles were analyzed by secondary ion mass spectrometry (SIMS). Diffusion coefficients calculated from these measurements indicate that Ag diffusion was greatly enhanced by carbon irradiation due to a combined effect of radiation damage on diffusion and the presence of grain boundaries in polycrystalline SiC samples.
"Effect of carbon ion irradiation on Ag diffusion in SiC" Tyler Gerczak, bin leng, Journal of Nuclear Materials Vol. 471 2016 220-232
"Effect of exposure environment on surface decomposition of SiC–silver ion implantation diffusion couples" Todd Allen, Kevin Field, Tyler Gerczak, Guiqiu Zheng, Journal of Nuclear Materials Vol. 456 2015 281-286 Link
SiC is a promising material for nuclear applications and is a critical component in the construction of tristructural isotropic (TRISO) fuel. A primary issue with TRISO fuel operation is the observed release of 110mAg from intact fuel particles. The release of Ag has prompted research efforts to directly measure the transport mechanism of Ag in bulk SiC. Recent experimental efforts have focused primarily on Ag ion implantation designs. The effect of the thermal exposure system on the ion implantation surface has been investigated. Results indicate the utilization of a mated sample geometry and the establishment of a static thermal exposure environment is critical to maintaining an intact surface for diffusion analysis. The nature of the implantation surface and its potential role in Ag diffusion analysis are discussed.
"Effect of exposure environment on surface decomposition of SiC–silver ion implantation diffusion couples" Tyler Gerczak, Guiqiu Zheng, Kevin Field, Todd Allen, Journal of Nuclear Materials Vol. 456 2015 281-286 Link
"Electron Microscopy Study of Pd, Ag, and Cs in Carbon Areas in the Locally Corroded SiC Layer in a Neutron-Irradiated TRISO Fuel Particle" Haiming Wen, Isabella van Rooyen, John Hunn, Tyler Gerczak, Journal of the European Ceramic Society Vol. 38 (2018) 2016 4173-4188 Link
"Observations of Ag diffusion in ion implanted SiC" Todd Allen, Tyler Gerczak, bin leng, Kumar Sridharan, Jerry Hunter, Andrew Giordani, Journal of Nuclear Materials Vol. 461 2015 314-324 Link
The nature and magnitude of Ag diffusion in SiC has been a topic of interest in connection with the performance of tristructural isotropic (TRISO) coated particle fuel for high temperature gas-cooled nuclear reactors. Ion implantation diffusion couples have been revisited to continue developing a more complete understanding of Ag fission product diffusion in SiC. Ion implantation diffusion couples fabricated from single crystal 4H-SiC and polycrystalline 3C-SiC substrates and exposed to 1500–1625 °C, were investigated by transmission electron microscopy and secondary ion mass spectrometry (SIMS). The high dynamic range of SIMS allowed for multiple diffusion régimes to be investigated, including enhanced diffusion by implantation-induced defects and grain boundary (GB) diffusion in undamaged SiC. Estimated diffusion coefficients suggest GB diffusion in bulk SiC does not properly describe the release observed from TRISO fuel.
"Observations of Ag diffusion in ion implanted SiC" Tyler Gerczak, bin leng, Kumar Sridharan, Jerry Hunter, Andrew Giordani, Todd Allen, Journal of Nuclear Materials Vol. 461 2015 314-324 Link
"Restructuring in high burnup UO2 studied using modern electron microscopy" Tyler Gerczak, Chad Parish, Philip Edmondson, Kurt Terrani, Journal of Nuclear Materials Vol. 509 2018 245-259 Link
Modern electron microscopy techniques were used to conduct a thorough study of an irradiated urania fuel pellet microstructure to attempt at an understanding of high burnup structure formation in this material. The fuel was irradiated at low power to high burnups in a light water reactor, proving ideal for this purpose. Examination of grain size and orientation with strict spatial selectivity across the fuel pellet radius allowed for capturing the progression of the restructuring process, from its onset to full completion. Based on this information, the polygonization mechanism was shown to be responsible for restructuring, involving formation of low-angle grain boundaries with their initiation occurring at the original high-angle grain boundaries of the as-fabricated pellet and at the gas bubble-matrix interfaces. The low-angle character of boundaries between the subdivided grains disappeared in the fully developed high burnup structure, likely due to creep deformation in the pellet.
Presentations:
" Fission Product and Actinide Distribution in the Sic Layer of Fissioned Triso Fuel Particles" Tyler Gerczak, John Hunn, Keith Leonard, Jeff Terry, 2017 ANS Annual Meeting [unknown]
"Development of Planar PyC/SiC Diffusion Couples to Investigate Irradiation Effects and Microstructural Variation on Fission Product Diffusion" Tyler Gerczak, Rachel Seibert, John Hunn, Brian Jolly, Austin Schumacher, Xunxiang Hu, Anne Campbell, GCR Program Review Meeting June 18-19, (2019)
"Development of planar PyC/SiC diffusion couples to investigate irradiation effects and microstructural variation on fission product diffusion" Tyler Gerczak, John Hunn, Brian Jolly, Austin Schumacher, Anne Campbell, John Dyer, Xunxiang Hu, HTR 2018 October 8-10, (2018)
"Diffusion Analysis of Fission Products in Tristructural-isotropic Coated Fuel Using Representative Diffusion Couples" Tyler Gerczak, Rachel Seibert, TMS 2020 February 23-27, (2020)
"Diffusion of fissile inventory in AGR-1 Triso fuel particles as a function of temperature & silver retention" Rachel Seibert, Jeff Terry, Tyler Gerczak, Kurt Terrani, John Hunn, Fred Montgomery, Charles Baldwin, The American Nuclear Society Annual Meeting June 17-21, (2018)
"Fabrication of PyC/SiC diffusion couples using fluidized bed CVD techniques for radiation enhanced diffusion testing" Brian Jolly, Tyler Gerczak, John Hunn, Austin Schumacher, Anne Campbell, The Materials Society Annual Conference March 11-15, (2018)
NSUF Articles:
CINR Awards Announced - Eight projects were selected Projects will take advantage of NSUF capabilities to investigate important nuclear fuel and material applications. Thursday, June 27, 2019 - Calls and Awards

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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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