Brandon Miller

"Characterization of Phases Formed Between U-PU-X Fuels and Fe-Based Cladding" Assel Aitkaliyeva, Brandon Miller, Thomas O'Holleran, James Madden, Rory Kennedy, Microscopy and Microanalysis Vol. 20 2014 1840-1841 Link
Uranium-plutonium-zirconium (U-Pu-Zr) and uranium-plutonium-molybdenum (U-Pu-Mo) fuels, known for their high burnup and good thermal response, have been considered as candidate fuels for advanced fast reactors. During their lifetime in the reactor, irradiation in combination with high temperatures can result in swelling of the fuel and its interaction with the cladding. As a result of the complex fuel-cladding chemical interaction (FCCI), integrity of fuel and cladding could be compromised and therefore should be comprehensively examined. As part of the fuel cycle research and development (FCRD) program, formation of intermetallic phases within fuel-cladding interaction zones was investigated in scanning electron microscope (SEM) and transmission electron microscope (TEM).
"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.
"Evolution of manganese–nickel–silicon-dominated phases in highly irradiated reactor pressure vessel steels" James Cole, Brandon Miller, Tim Milot, G. Robert Odette, Peter Wells, Takuya Yamamoto, Yuan Wu, Acta Materialia Vol. 80 2014 205-219 Link
Formation of a high density of Mn–Ni–Si nanoscale precipitates in irradiated Cu-free and Cu-bearing reactor pressure vessel steels could lead to severe unexpected embrittlement. Models long ago predicted that these precipitates, which are not treated in current embrittlement prediction models, would emerge only at high fluence. However, the mechanisms and variables that control Mn–Ni–Si precipitate formation, and their detailed characteristics, have not been well understood. High flux irradiations of six steels with systematic variations in Cu and Ni contents were carried out at ~295 °C to high and very high neutron fluences of ~1.3 × 1020 and ~1.1 × 1021 n cm-2. Atom probe tomography shows that significant mole fractions of Mn–Ni–Si-dominated precipitates form in the Cu-bearing steels at ~1.3 × 1020 n cm-2, while they are only beginning to develop in Cu-free steels. However, large mole fractions of these precipitates, far in excess of those found in previous studies, are observed at 1.1 × 1021 n cm-2 at all Cu contents. At the highest fluence, the precipitate mole fractions primarily depend on the alloy Ni, rather than Cu, content. The Mn–Ni–Si precipitates lead to very large increases in measured hardness, corresponding to yield strength elevations of up to almost 700 MPa.
"Fuel-Cladding Interaction Between U-Pu-Zr Fuel and Fe" Assel Aitkaliyeva, James Cole, Brandon Miller, Cynthia Adkins, James Madden, Metallurgical and Materials Transactions E Vol. 2 2015 220-228 Link
This work investigates fuel-cladding chemical interaction (FCCI) between U-25Pu-14Zr (in wt pct) fuel and pure Fe at elevated temperatures, understanding of which is critical for evaluation of the fuel performance. Phases and microstructure formed in the quaternary uranium-plutonium-zirconium-iron (U-Pu-Zr-Fe) system were characterized using the transmission electron microscopy technique. Phases formed within the FCCI layer were identified using selective area electron diffraction (SAED) analysis as Fe2U (Fd- m), Fe2Zr (Fd-3m), a-U (Cmcm), Fe2Pu (Fd-3m), ß-Pu (C12/m1), and ß-Zr (Im-3m). U.S. Government Work. Not Protected by U.S. Copyright. Manuscript submitted June 23, 2015.
"In-Pile Irradiation Induced Defects and the Effect on Thermal Diffusivity of MgO" Pavel Medvedev, Brandon Miller, Donald Moore, Juan Nino, Cynthia Adkins, Journal of Nuclear Materials Vol. 434 2013 90-96 Link
The effects of neutron irradiation temperature and dose on thermal diffusivity are investigated by comparing non-irradiated and in-pile irradiated MgO samples. MgO pellets were irradiated in-pile of the Advanced Test Reactor at Idaho National Laboratory. Samples were irradiated at 623 and 973 K to fast neutron fluences of ~1 x 1025 (1.5 dpa) and ~2 x 1025 n/m2 (3 dpa). Post irradiation examination included X-ray diffraction, scanning electron microscopy, laser flash thermal diffusivity, and transmission electron microscopy. Neutron irradiation of MgO causes a significant reduction in the thermal diffusivity (46 to 72% at room temperature) due to irradiation-induced defects. The radiation induced thermophysical and structural evolution of MgO is reported.
"Microstructure and mechanical behavior of neutron irradiated ultrafine grained ferritic steel" Ahmad Alsabbagh, Apu Sarkar, Brandon Miller, Jatuporn Burns, Leah Squires, Douglas Porter, James Cole, Korukonda Murty, Materials Science and Engineering A Vol. 615 2014 128-138 Link
Neutron irradiation effects on ultra-fine grain (UFG) low carbon steel prepared by equal channel angular pressing (ECAP) have been examined. Counterpart samples with conventional grain (CG) sizes have been irradiated alongside with the UFG ones for comparison. Samples were irradiated in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) to 1.37 dpa. Atom probe tomography revealed manganese and silicon-enriched clusters in both UFG and CG steel after neutron irradiation. Mechanical properties were characterized using microhardness and tensile tests, and irradiation of UFG carbon steel revealed minute radiation effects in contrast to the distinct radiation hardening and reduction of ductility in its CG counterpart. After irradiation, micro hardness indicated increases of around 9% for UFG versus 62% for CG steel. Similarly, tensile strength revealed increases of 8% and 94% respectively for UFG and CG steels while corresponding decreases in ductility were 56% versus 82%. X-ray quantitative analysis showed that dislocation density in CG increased after irradiation while no significant change was observed in UFG steel, revealing better radiation tolerance. Quantitative correlations between experimental results and modeling were demonstrated based on irradiation induced precipitate strengthening and dislocation forest hardening mechanisms.
"Relationship between lath boundary structure and radiation induced segregation in a neutron irradiated 9wt.% Cr model ferritic/martensitic steel" Todd Allen, Heather Chichester, Kevin Field, Brandon Miller, Kumar Sridharan, Journal of Nuclear Materials Vol. 445 2013 143-148 Link
Ferritic/Martensitic (F/M) steels with high Cr content posses the high temperature strength and low swelling rates required for advanced nuclear reactor designs. Radiation induced segregation (RIS) occurs in F/M steels due to solute atoms preferentially coupling to point defect fluxes which migrate to defect sinks, such as grain boundaries (GBs). The RIS response of F/M steels and austenitic steels has been shown to be dependent on the local structure of GBs where low energy structures have suppressed RIS responses. This relationship between local GB structure and RIS has been demonstrated primarily in ion-irradiated specimens. A 9 wt.% Cr model alloy steel was irradiated to 3 dpa using neutrons at the Advanced Test Reactor (ATR) to determine the effect of a neutron radiation environment on the RIS response at different GB structures. This investigation found the relationship between GB structure and RIS is also active for F/M steels irradiated using neutrons. The data generated from the neutron irradiation is also compared to RIS data generated using proton irradiations on the same heat of model alloy.
"STEM-EDS/EELS and APT characterization of ZrN coatings on UMo fuel kernels" Lingfeng He, Mukesh Bachhav, Dennis Keiser, Emmanuel Perez, Brandon Miller, Jian Gan, Ann Leenaers, Sven Van den Berghe, Journal of Nuclear Materials Vol. 511 2018 174-182 Link
"TEM examination of phases formed between U–Pu–Zr fuel and Fe" Assel Aitkaliyeva, James Cole, Brandon Miller, Cynthia Adkins, James Madden, Journal of Nuclear Materials Vol. 467 2015 717-723 Link
Exposure to high temperatures and irradiation results in interaction and interdiffusion between fuel and cladding constituents that can lead to formation of undesirable brittle or low-melting point phases. A diffusion couple study has been conducted to understand fuel-cladding interaction occurring between Ue22Pue4Zr (in wt%) fuel and pure Fe at elevated temperatures. The phases formed within fuel claddingchemical interaction (FCCI) layer have been characterized in the transmission electron microscope (TEM). The phases formed within FCCI layer have been identified as Fe2U (Fd-3m), FeU6 (I4/mcm), Fe2Zr (Fd-3m), FeZr2 (I4/mcm), Fe2Pu (Fd-3m), UZr2 (P6/mmm), b-Zr (Im-3m), and ZrO2 (Fm-3m).
""Late Blooming Phases in RPV Steels: High Fluence Neutron and Ion Irradiations" Collin Knight, Brandon Miller, Tim Milot, G. Robert Odette, Peter Wells, Takuya Yamamoto, NuMat 2012 October 22-25, (2012)
"Advanced Characterization of Irradiated UO2 Fuel" Lingfeng He, Michael Moorehead, Brandon Miller, Jason Harp, Xianming Bai, TMS 2018 March 11-15, (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)
"Late Blooming Phases in RPV Steels at High Fluence and Flux" James Cole, Collin Knight, Brandon Miller, G. Robert Odette, Peter Wells, Takuya Yamamoto, International Group of Radiation Damage Mechanisms 17th Semiannual Meeting May 19-24, (2013)
"Poster - Examining microstructural differences in irradiated HT9 correlated with differences in processing prior to irradiation" Theresa Mary Green, Li He, Todd Allen, Brandon Miller, Lingfeng He, NUMAT 2018 October 15-18, (2018)
"Recent observations from the microstructural characterization of irradiated U-Mo fuels using advanced techniques" Dennis Keiser, Brandon Miller, Jian Gan, Lingfeng He, Daniel Jadernas, Mukesh Bachhav, NUMAT 2018 October 15-18, (2018)
"TEM Characterization of Dislocation Loops and Precipitates in Irradiated RPV Steels" James Cole, Collin Knight, Brandon Miller, G. Robert Odette, Takuya Yamamoto, International Group of Radiation Damage Mechanisms 17th Semiannual Meeting May 19-24, (2013)
"The Evolution of Late Blooming Phases from High to Very High Fluence" Collin Knight, Brandon Miller, G. Robert Odette, Peter Wells, Takuya Yamamoto, The Minerals, Metals and Materials Society 2013 Annual Meeting March 3-7, (2013)
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