Graduate Fellows
Ousmane Ndiaye
My name is Ousmane Ndiaye. I am halfway through my second year as a PhD student at the University of Illinois Urbana-Champaign (UIUC). I am pursuing a PhD in nuclear engineering with a focus on structural materials. I am also a fellow in the Nuclear Science and Security Consortium (NSSC).
My research is related to additive manufacturing (AM) of nuclear materials. I am studying how process parameters (such as laser powder, scan speed, and powder composition) may affect the microstructure and mechanical properties of materials. Process parameters may also affect a material’s response to heat flux and to radiation to make the material more susceptible to recrystallization or delaying grain growth. A particular material of interest for my research is laser powder bed fusion (LPBF) 316H .316H which is a stainless steel (SS) that is used as a structural material in nuclear reactors.
During the summer 2024, I interned at ORNL under the mentorship of Dr. Tim Graening Seibert in the Advanced Nuclear Materials Group in the Materials Sciences & Technology Division. Dr. Seibert and I worked on high temperature tensile testing of Tungsten-Rhenium alloys that were printed from an electron beam melting printer.
The internship taught me how to perform high temperature testing and how to derive correlation between microstructure and mechanical properties. I also learned how process parameters can affect mechanical properties for printed refractory metals.
My internship at ORNL has provided me with the opportunity to learn from world class scientists and leaders. I also had the opportunity to tour world class facilities at ORNL such as the High Flux Isotope Reactor (HFIR), the Manufacturing Demonstration Facility (MDF), and the Spallation Neutron Source (SNS). I was able to network with potential collaborators on work that may provide data for my PhD research. Through the mentorship with Dr. Seibert, I was able to enhance my skills as a researcher in terms of developing research proposals, conducting data analysis, and giving technical presentations. ORNL has motivated me to become a researcher; and to strive to be on the cutting edge of structural materials for fusion and fission reactors.
Alec Pfundheller
My name is Alec Pfundheller. I am finishing the third year of my PhD in Nuclear Engineering at Texas A&M University. I am also a fellow of the Enabling Technologies and Innovation Consortium (ETI).
My research concerns the radiation response of additively manufactured (AM) 316L stainless steel. This involves the use of advanced microscopy techniques including Scanning Electron Microscopy (SEM), Electron Backscatter Diffraction (EBSD), Micropillar Compression, and Transmission Electron Microscopy (TEM). Currently, I am conducting research into ion irradiated AM 316L stainless steel’s response to cross-sectional micropillar compression throughout regions with differing printing laser wattage. This will allow us to create multiple stress vs. strain curves throughout irradiated and unirradiated regions of the sample. After preliminary analysis of void induced swelling of AM and wrought 316L stainless steel, I plan to investigate the damage and dislocations created by the irradiation using flash etching, and TEM microscopy.
This summer, I interned at ORNL under the mentorship of Dr. Stephen Taller in the Nuclear Fuel Cycle Engineering Division. Together, we examined the differences between radiation induced microstructures in AM type 316 stainless steels from either ions or neutrons to inform physics-based modeling of how features specific to the fabrication process impact their evolution. Similar techniques to my PhD research were utilized, primarily TEM microscopy at the LAMDA laboratory at ORNL. Through this internship, I gained insight into troubleshooting hardware and software issues involving the TEM microscope as well as invaluable experience and knowledge of imaging dislocations and oxides that will benefit the ETI and DOE-NE AMMT projects, and my dissertation research.
I am extremely grateful to the DNN ETI Consortium and the research staff at ORNL for making my internship possible. It has allowed me to interact with the nation’s leading experts in nuclear engineering and radiation materials science and has provided me with the knowledge and skills that will surely contribute to my dissertation. Overall, I enjoyed this experience very much and would recommend an internship at ORNL to anyone who is considering a career in a national laboratory.
Shae Cole
My name is Shae Cole. I am a second-year graduate student at Georgia Institute of Technology under the advisement of Dr. Anna Erickson. My thesis research involves fabrication and characterization of organic based semiconductors for radiation detection and degradation.
I have had the honor of interning at ORNL for the summer of 2024 under the advisement of Nathan Rowe in the Verification Technology Group of the Nuclear Nonproliferation Division. My research involved creating and printing tamper detection devices. During my time at ORNL I have been able to attend many seminars, talks, workshops, and presentations. I was able to tour the Spallation Neutron Source and the National Transportation Research Center. The expert advice and mentorship have helped me get a new perspective on the national labs as well as my academic research.
Francisco Gonzalez-Castillo
My name is Francisco Gonzalez-Castillo. I am a 4th Year PhD student at the University of Texas at Austin working under the advice of Dr. Derek Haas. My research focuses on designing and developing additive manufacturing systems for applications in nuclear safeguards.
I was privileged to spend my summer at Oak Ridge National Laboratory (ORNL) where I worked on developing nuclear safeguard technologies with the Verification Technologies Group in the Nuclear Nonproliferation Division. My mentor, Nathan Rowe, enabled me to work on exciting projects within the group while keeping up with my academic research. The internship gave me valuable insights and plenty of hands-on experience that has shaped my understanding of what it means to be a researcher.
Joel Castillo
My name is Joel Castillo. I am a sixth year PhD student in Radiochemistry at the University of Nevada, Las Vegas (UNLV). For my PhD dissertation, I am studying the speciation of actinides in acidic media extracted into organic media with organophosphorus and/or diglycolamide ligands.
During summer 2024, I was an intern at ORNL. I worked in the Physics Division of the Physical Sciences Directorate. I was assigned to the Neutrino Research Group under Dr. Jason Newby as my supervisor and with Dr. Chong-Hang Yu as my mentor. For my internship, I am experimenting with 3D printing and liquid resin synthesis as a means for producing ultra-low background plastics. These plastics should have the durability and light-transmission properties necessary to be able to encapsulate the central Ge-76 source in the LEGEND-1000 project. This project is a massive collaboration that will ultimately enable the detection of neutrinoless double beta decay.
Because of this internship experience at ORNL, I have been able to participate in several seminars, even on subjects not related to my own field of research. Additionally, I have been fortunate to tour the Spallation Neutron Source (SNS) with other interns as well as explore different areas of ORNL to really get a taste of the astounding breadth of work being done at ORNL. As a result of one of the talks I attended, I got to email the presenter and she was able to connect me to neutron scattering scientists at SNS. We scheduled time for me to visit their offices and receive consultation on how I might apply neutron analytical techniques to my own graduate studies at UNLV. This prompted a good discussion about capabilities at SNS and opened the door to future collaborations. Finally, the internship has given me the opportunity to work and to interact with several post-docs and other graduate students across the Physical Sciences Directorate.
Lavanya Upadhyaya
My name is Lavanya Upadhyaya, and I am a nuclear engineering PhD student at Texas A&M University (TAMU). I have a graduate fellowship in the Nuclear Science and Security Consortium (NSSC).
My graduate research focuses on the interactions between structural alloys and fuel salt in molten salt reactors (MSRs) to determine corrosion-resistant high-temperature structural alloys. I tested and analyzed six candidate alloys for MSRs before and after exposure to FLiNaK (LiF-KF-NaF) molten salt at reactor-grade conditions. Structural changes were examined for each metal using multiple techniques. These analyses focus on chromium (Cr) dissolution through the grain boundaries, which presents failure mechanisms for materials during reactor operation. More in-situ corrosion testing and further study will be completed.
During the summer of 2024, I completed a 10-week internship at ORNL in the Nuclear Nonproliferation Division under the mentorship of Dr. Sunil Chirayath. For my project, I applied proliferation resistance (PR) methodologies to various reactor types to perform a thorough systems analysis. My research tasks included 1) an in-depth literature review of PR and fuel cycle methodologies and 2) the calculation of eight attributes to determine the intrinsic PR at each stage of the fuel cycle for two reactor types: Pressurized Heavy Water Reactor (PHWR) and Light Water Reactor (LWR). The PR was evaluated using the Proliferation Resistance Analysis and Evaluation Tool for Observed Risk (PRAETOR) framework. This comprehensive analysis included plotting the data to show any vulnerabilities in the fuel cycles at each stage.
Apart from my internship, I participated in opportunities to enhance my knowledge and skills. I engaged in short courses on nuclear nonproliferation and Python for beginners. Moreover, I attended professional development talks from early career scientists who shared their journeys and research activities. I also had the privilege to tour multiple facilities and labs, including HFIR, SNS, MDF, REDC, the Safeguards Security Lab, and the GRID-C Facility. Lastly, I attended the Institute of Nuclear Materials Management (INMM) Conference in July 2024 with my advisor, which was a great learning experience.
My experience at ORNL was valuable due to my engagement in a new research project and the opportunities that encouraged professional and personal growth. The time I received to network with various staff scientists across ORNL has the potential to open doors for future collaborations and career growth. I recommend this experience to my peers and encourage them to be passionate and interested in science!
Rebecca Manns
My name is Rebecca Manns. I am a third-year radiochemistry doctoral student at the University of Nevada, Las Vegas, and an affiliate of the Nuclear Science and Security Consortium (NSSC).
My research includes the examination of fuel cladding chemical interactions (FCCI) between ceramic fuels, such as UO2 and doped-UO2, and cladding materials, such as Zircaloy and FeCrAl, using the diffusion couple technique. These FCCIs can form different chemical species at the increased temperatures seen in off-normal reactor conditions which can affect the integrity of the fuel assemblies. Knowledge of how the interaction zones form these species is crucial for approving new fuels and cladding materials; and is also of particular importance to nuclear forensics.
During summer 2024, I was an intern at ORNL working alongside my mentor, Toya Beiswenger. My internship research objectives were to: 1) examine the influence of the order of analytical tools on sample analysis results, and; 2) examine potential distortions in the spectral analysis of smaller particles relative to macroscopic particles of uranium chemistries. These research objectives were addressed by examining three different particle sizes (6 μm, 10 μm, and 25 μm) of four different uranium chemistries (U3O8, Studtite, UO2, and UO3) using scanning electron microscopy (SEM) and Raman spectroscopy. Two different workflows were established to examine the influence of the SEM and Raman techniques on the spectral analysis of these uranium chemistries at the determined particle sizes. This internship will result in publishing a paper to summarize the research findings, and a presentation (along with my mentor) to the radiochemistry department at UNLV.
Through the ORNL internship, I was able to participate in professional development activities as well as tour several ORNL research facilities. The professional development activities included guidelines on how to build a better resume and how to format digital information. I also attended talks from early career scientists who shared their journeys and their research activities. Facilities tours included HFIR, SNS, and MDF where I got to see more of the exciting science taking place at ORNL.
My ORNL experience has been very rewarding. There is not much that I would change. The arranged talks and tours were informative, and there were many opportunities for networking. Overall, this was a very rewarding experience. I would recommend interning at ORNL to any graduate student considering a career at ORNL.
Josephine Libero
As an NNSC fellow and PhD candidate at the University of Nevada, Las Vegas I perform an experimental investigation of phase equilibria, thermodynamics and intermetallic species in technetium-actinide binary systems. In this work I produce metallic samples such as diffusion couples and equilibrated alloys and then characterize them using electron microscopy techniques, diffraction, and a physical properties measurement system.
My goal for summer 2024 was to expand the breadth of my electron microscopy experience by learning techniques unavailable at UNLV such as focused ion beam (FIB) and transmission electron microcopy (TEM). My experience and goals matched me with ORNL’s Chad Parish and Zach Brubaker. This summer I had the opportunity to intern at ORNL in the Nuclear Energy Materials Microanalysis Group under Chad Parish as part of a collaboration with the Nuclear Nonproliferation Division. My work involved creating a workflow for microanalysis of samples by testing mounting techniques to find one with sufficient robustness for atomic force microscopy (AFM) testing. This work allowed me to learn a new skill, FIB sample preparation, and to observe/assist with many new techniques such as TEM, transmission Kikuchi diffraction (TKD), and AFM.
Additionally, the internship gave me an opportunity to tour many ORNL facilities including the Spallation Neutron Source (SNS), the High Flux Isotope Reactor (HFIR), and the Manufacturing Demonstration Facility (MDF). I was able to attend an experiment at a user facility with Zach Brubaker and observe the set-up process for testing at the ARCS beam line at SNS.
Finally, I was able to make connections and network with a range of scientists and interns at ORNL this summer. The mentorship I received will impact my future, and I have gained many skills to take with me to further my research.
Matthew deJong
My name is Matthew deJong. I am beginning my fourth year in graduate school at North Carolina State University (NCSU). I am pursuing a PhD in Materials Science and Engineering while performing research in Nuclear Engineering.
As a fellow of the Nuclear Science and Security Consortium (NSSC), my doctoral research is focused on the characterization of additively manufactured (AM) materials. I am researching how the microstructure of oxide dispersion strengthened (ODS) steel synthesized via Laser Powder Bed Fusion (LPBF) is influenced by changes in the preceding metal powder. This powder is produced through gas atomization reaction synthesis (GARS) in batches of varying chemistries. ODS steel is a potential candidate in the nuclear industry for structural applications in high temperature environments under radiation exposure. The ability to produce complex geometries through LPBF reduces the need for joining processes which can impact the microstructure at the weld and weaken the material.
During the summer 2023, I interned at ORNL under the mentorship of Dr. Chad Parish and Dr. Holden Hyer. Both of my mentors were extremely welcoming and helped me gain a better understanding of both the processing and characterization sides of additive manufacturing. I was taught how to print samples through LPBF, as well as how to characterize the grain structure of samples through Transmission Kikuchi Diffraction. Although I received a lot of experience in Transmission Electron Microscopy at NCSU, my mentors showed me new ways to improve data collection, both in terms of sample preparation and while using microscopic instruments.
During my summer internship of 2024, I was mentored my Dr. Soumya Nag at the Manufacturing Demonstration Facility (MDF). I gained experience characterizing 316L in the form of consolidated parts and powder, as well as nickel copper alloys with various techniques, including Electron Back Scatter Diffraction (EBSD), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). I have also gathered literature on 316L steel microstructure and have had the privilege of being able to write a paper on my findings.
I have thoroughly enjoyed these internships and working with employees at ORNL. Working with researchers at ORNL and participating in networking opportunities have shown me the diverse roles people have in research at ORNL. I have gained hands-on experience with characterization equipment, a better understanding of different alloys, and have further developed my writing skills.
Lance Drouet
My name is Lance Drouet. I am a fellow of the Nuclear Science and Security Consortium (NSSC) and a Ph.D. student in Nuclear Engineering at the University of Tennessee, Knoxville. My doctoral research is focused on investigating the use of Artificial intelligence (AI) and Machine learning (ML) techniques on nuclear data and data generated from simulated low-fidelity models to improve the optimization of nuclear system design.
During the summer of 2023, I interned at ORNL under the mentorship of Dr. Rike Bostelmann. While at ORNL this summer, I was given the opportunity to work with the developers of SCALE (Standardized Computer Analysis for Licensing Evaluation), which is a comprehensive modeling and simulation (M & S) suite for nuclear safety analysis and design; and which has been developed and maintained by ORNL under contract with the U.S. Nuclear Regulatory Commission, U.S. Department of Energy, and the National Nuclear Security Administration. The tool performs reactor physics, criticality safety, radiation shielding, and spent fuel characterization for nuclear facilities and transportation/storage package designs to quantify the effects of nuclear data uncertainties on spent fuel metrics. I was fortunate to work directly with the SCALE developers to improve the end-user experience and, in the process, observe firsthand the software development life cycle for this major M & S suite of tools.
My internship at ORNL has contributed to my doctoral research by connecting the concept of nuclear data uncertainties, uncertainty quantification (UQ) in M&S, and the importance of these metrics towards real applications. I found ORNL’s diverse and welcoming environment to be instantly conducive to nurturing my curiosity, technical capabilities, and personal growth. The connections and knowledge I have gained throughout the summer have built my confidence in my career prospects and in continuing my Ph.D. research.
Brad Nethercutt
I am currently a PhD candidate in nuclear engineering at Penn State University and have been a member of the Monitoring Technologies and Verification (MTV) Consortium since 2021. My thesis research focuses on utilizing an epithermal neutron chopper system at the Penn State Breazeale Reactor to identify new signatures for nuclear forensic characterization through neutron activation analysis.
As an ORNL intern during the summer of 2023, I worked under Dr. Vincent Jodoin within the Incident Modeling and Computational Sciences Group on a verification and validation effort of Water Surface Burst, a nuclear fallout simulation code. Before this internship, I had very little introduction to the post-detonation side of nuclear forensics. Now, having hands-on experience using several tools developed at ORNL in pursuit of the NNSA’s nuclear forensics missions, I can say that this experience has uniquely broadened my knowledge of the field.
My internship provided a great opportunity to network with ORNL scientists and get their insight on their career paths and what drew them to Oak Ridge. Everyone I spoke to was eager to answer my questions. I was very impressed by the breadth of work being done at ORNL, both within the Nuclear Nonproliferation Division and elsewhere. As I look beyond graduation, I am excited by the prospect of returning to ORNL to begin a career in nuclear forensics.
Dinara Ermakova – UC Berkeley PhD Student (NSSC Fellow)
During the summer 2022, Dinara interned in the ORNL Nuclear Energy and Fuel Cycle Division working under Drs. Andrew Worrall and Jin Whan Bae. Dinara’s research was focused on the electricity generation sector which is responsible for 25% of the world’s greenhouse gas (GHG) emissions and thus has been the focus of efforts to transition to clean energy and sustainable development in many nations. According to Dinara’s research, the rapid development of renewable energy sources and technologies will require an enormous amount of raw materials to replace coal and gas plants and increase in the capacity to handle growing electricity demand because renewable energy sources have a low-power density and intermittent behavior. During her internship, she was explored the opportunity for remining abandoned mines waste as a way to satisfy demand, facilitate cleanup activities, and engage local communities. The results of her work will be published in a technical report. In addition, Dinara was able to work on her dissertation project, assessing the material demand for the projected transition and its transportation carbon footprint. Apart from work, Dinara says, she that her internship provided the opportunity to meet “many brilliant people and make friends at the Lab.