Senior Technical Advisor, Advanced Material Systems
Senior Technical Advisor, Advanced Material Systems


Dr. Isabella J. van Rooyen joined Pacific Northwest National Laboratory (PNNL) in December 2021 as an advisor for Advanced Material Systems where she is developing and implementing new nuclear materials development and advanced manufacturing strategies. She is the United States representative on the International Advanced Manufacturing and Materials Engineering Taskforce for the generation IV international forum (GIF) and the Material Development technical area lead for the Advanced Materials and Manufacturing Technologies (AMMT) program for the Department of Energy (DOE) Nuclear Energy Enabling Technologies. Prior to joining PNNL, Dr. van Rooyen supported DOE's vision and needs in advanced materials and manufacturing planning and execution as the national technical director for the Advanced Methods for Manufacturing program of the DOE Nuclear Engineering Office.

Dr. van Rooyen’s cross-cutting research spans advanced manufacturing processes, advanced material development, and advanced characterization techniques. Her leadership roles have furthered advanced manufacturing techniques in laser materials processing, casting processes, powder metallurgy, and additive manufacturing processes. She initiated and led projects on the development of metal, ceramic, and matrix materials for high-temperature applications as well as various materials for nuclear fuels. In addition, she pioneered, optimized, and championed novel characterization and electron microscopic techniques to enable and improve fission product mechanistic studies and product performance and qualification at all scales and across material life spans. She holds a PhD in physics from Nelson Mandela University, a master’s degree in metallurgy from the University of Pretoria, and an MBA from Northwest University.

Research Interest

  • Material development for extreme environments (e.g., high-temperature, corrosion, and neutron irradiation applications) and nuclear fuels
  • Novel characterization techniques for nuclear and non-nuclear materials specifically miniaturization and in situ monitoring
  • Advanced materials manufacturing methods
  • Integrating approaches through full product lifecycles
  • Modeling and simulations for accelerating new technologies

Disciplines and Skills

  • Material development for high-temperature applications including silicon carbide, zircaloy, graphite, beryllium, titanium, nickel-based alloys, tungsten-copper, and ceramic-matrix composite materials 
  • Material development for nuclear fuels including uranium dioxide (UO2), uranium oxycarbide (UCO), uranium silicide (U3Si2), and TRi-structural ISOtropic particle (TRISO) fuel 
  • Novel characterization techniques for nuclear and non-nuclear materials including precession electron diffraction, Raman, X-ray diffraction, and nano-indentation hardness 
  • Application of electron microscopic techniques for nuclear and non-nuclear materials in scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning TEM (STEM), atom probe tomography (APT), and high-resolution TEM (HRTEM) advanced materials manufacturing methods especially for nuclear reactor applications
  • Material engineering and development for advanced material systems
  • Design, fabrication, qualification, and supply chain management for nuclear materials systems
  • Laser materials processing including joining, cutting, welding, cladding, additive manufacturing, meso- and micro-processing
  • Powder and nanopowder metallurgy for high-temperature materials using techniques like sintering and hot isostatic pressing (HIP)
  • Studies of the impact of nanotechnology on the metals and powder metallurgy industry


  • PhD in physics, Nelson Mandela University
  • Project management certificate, University of Pretoria
  • MBA in business, Northwest University
  • MSc in metallurgy, University of Pretoria
  • BSc (Honors) in metallurgy, University of Pretoria
  • BSc in metallurgy, University of Pretoria

Affiliations and Professional Service

  • American Society of Mechanical Engineers (ASME), January 2022 to present
  • ASME standards committee member: Manufacturing and Advanced Manufacturing (MAM); Subcommittee member on Additive Manufacturing; and member of the MAM working group on Additive Manufacturing for Nonmetallic Materials Applications, 2022 to present
  • Adjunct professor, University of Idaho, 2021 to present
  • American Nuclear Society (ANS) Idaho, 2021 to present
  • United States representative on the generation IV (GIF) international advanced manufacturing and materials engineering taskforce, task lead for the modeling and simulation techniques enabling acceleration of qualification processes, 2019 to present
  • Woman in Nuclear USA and Idaho, 2018 to present
  • Affiliate Faculty Member and Graduate Faculty Member of the Material Science and Engineering Department and Nuclear Engineering Department of University of Florida, 2017 to present
  • The Minerals, Metals & Materials Society (TMS) Additive Manufacturing Committee member, 2017 to present; Nuclear Materials Committee member, 2014 to present
  • Microanalysis society (MAS) and microscopy and spectrograph association (MSA), 2012 to present

Awards and Recognitions

  • National Reactor Innovation Center (NRIC) award, 2020
  • Employee Special Recognition Award, Nuclear Science and Technology, Idaho National Laboratory (INL), 2019, 2017, 2014, 2013
  • Employee Exceptional Contributions Award, Fuel Design and Development Department, INL, 2018
  • Centre for Advanced Energy Studies affiliate in recognition of significant contribution to the Center of Advanced Energy Studies, 2015, 2014, 2013
  • INL Laboratory Director’s award for outstanding scientific paper published in fiscal year 2014, 2015
  • Nominated for the Laboratory Director's Award for Exceptional Scientific Achievement, 2013
  • National (South Africa) Excellence award finalist (one of four) for outstanding woman in engineering and technology for excellence in national engineering sector level, 2010
  • Outstanding Performance Appreciation Award for the development of a unique silver spiking technique and the technical leadership in fuel characterization projects, PBMR Labs, 2009


  • I.J. van Rooyen, P. Sabharwall, “Heat exchangers fabricated by additive manufacturing, related components, and related methods,”  US Patent no. 11,383,302 B2 July 12, 2022
  • C. Downey, I.J. van Rooyen, L. Nunez, "Fabrication of High Entropy Alloys with Additive Manufacturing Utilizing Commercial Alloys and In situ Process Control," BA1296, provisional patent application no. 63/292,121; December 21, 2021 (provisional)
  • I.J. van Rooyen, Y. Ballout, “Gap maintaining structures enabled by advanced manufacturing processes as part of integrated manufacturing process of a system with embedded sensor(s),” Provisional patent filed December 2020, utility patent application 17/643,628; December 10, 2021 (pending)
  • I.J. van Rooyen, S.R. Morrell, "Methods of additively manufacturing a structure and related structures," US Patent no. 11,177,047 B2; Nov 16, 2021
  • I.J. van Rooyen, C.J. Parga, "Methods and apparatus for additively manufacturing structures using in situ formed additive manufacturing materials," US Patent no. 11,014,265 B2; May 25, 2021
  • I.J. van Rooyen, P. Sabharwall, “Techniques for incorporating sensors into apparatuses and systems,” BEA Docket No. BA-1102: Provisional patent application no. 62/930,865 filed November 5, 2019; nonprovisional application no. 17/089,922 filed November 5, 2020 (pending)
  • G.W. Griffith, I.J. van Rooyen, “Nuclear fuel elements including protective structures, and related methods,” BEA Docket No. BA-1026:  Provisional patent application no. 62/928,037 filed October 30, 2019; nonprovisional application no. 17/072,903 filed October 16, 2020 (pending)
  • I.J. van Rooyen, S.R. Morrell, “Methods of forming structures and fissile fuel materials by additive manufacturing,” US Patent no. 10,614,923 B2; April 7, 2020


Selected Publications

  • Mauseth T., M. Dunzik-Gougar, S. Meher, and I. van Rooyen. 2023. "Determining the Tensile Strength of Fuel Surrogate TRISO-coated Particle Buffer, IPyC, and Buffer-IPyC Interlayer Regions." Journal of Nuclear Materials 583. PNNL-SA-181513. doi:10.1016/j.jnucmat.2023.154540
  • Shen, Y.-L., M. G. Abdo, and I. J. Van Rooyan. 2022. "Numerical Study of Effective Thermal Conductivity for Periodic Closed-Cell Porous Media.” Transport in Porous Media 143 (2): 245-269.
  • Shen, Y.-L., M. G. Abdo, and I. J. Van Rooyen. 2022., “Thermal Conductivity of Crack-Containing Media: A Numerical Study.” Journal of Composite Materials 56 (16): 2495-2508.
  • Kane, J. J., D. W. Marshall, N. L. Cordes, W. C. Chuirazzi, B. Kombaiah, I. van Rooyen, and J. D. Stempien. 2022. “3d Analysis of TRISO Fuel Compacts Via X-Ray Computed Tomography.” Journal of Nuclear Materials 565.
  • Ahmed Simon, A., B. Badamchi, H. Subbaraman, Y. Sakaguchi, L. Jones, H. Kunold, I. J. van Rooyen, and M. Mitkova. 2021. “Introduction of Chalcogenide Glasses to Additive Manufacturing: Nanoparticle Ink Formulation, Inkjet Printing, and Phase Change Devices Fabrication.” Scientific Reports 11 (1).
  • Mondal, K., L. Nuñez, C. M. Downey, and I. J. van Rooyen. 2021. “Thermal Barrier Coatings Overview: Design, Manufacturing, and Applications in High-Temperature Industries.” Industrial & Engineering Chemistry Research 60 (17): 6061-6077.
  • Fu, Z., I. J. van Rooyen*, M. Bachhav, and Y. Yang. 2020. “Microstructure and Fission Products in the Uco Kernel of an Agr-1 TRISO Fuel Particle after Post Irradiation Safety Testing.” Journal of Nuclear Materials 528. (*corresponding author)
  • Olivier, E. J., J. H. Neethling, and I. J. van Rooyen. 2020. “Investigation of the Structure and Chemical Nature of Pd Fission Product Agglomerations in Irradiated TRISO Particle Sic.” Journal of Nuclear Materials 532.
  • Peng, Q., N. Chen, Z. Jiao, I. J. van Rooyen, W. F. Skerjanc, and F. Gao. 2019. “Reveal the Fast and Charge-Insensitive Lattice Diffusion of Silver in Cubic Silicon Carbide Via First-Principles Calculations.” Computational Materials Science 170.
  • Vandegrift, J. L., P. M. Price, J.-P. Stroud, C. J. Parga, I. J. Van Rooyen, B. J. Jaques, and D. P. Butt. 2019. “Oxidation Behavior of Zirconium, Zircaloy-3, Zircaloy-4, Zr-1nb, and Zr-2.5nb in Air and Oxygen.” Nuclear Materials and Energy 20.
  • Rosales, J., I. J. van Rooyen, and C. J. Parga. 2019. “Characterizing Surrogates to Develop an Additive Manufacturing Process for U3si2 Nuclear Fuel.” Journal of Nuclear Materials 518: 117-128.
  • Parga, C. J., I. J. van Rooyen, and E. P. Luther. 2018. “Fuel – Clad Chemical Interaction Evaluation of the Treat Reactor Conceptual Low-Enriched-Uranium Fuel Element.” Journal of Nuclear Materials 512: 252-267.
  • Meher, S., I. J. van Rooyen, and T. M. Lillo. 2018. “A Novel Dual-Step Nucleation Pathway in Crystalline Solids under Neutron Irradiation.” Scientific Reports 8 (1).
  • Wen, H., I. J. van Rooyen, J. D. Hunn, and T. J. Gerczak. 2018. “Electron Microscopy Study of Pd, Ag, and Cs in Carbon Areas in the Locally Corroded Sic Layer in a Neutron-Irradiated TRISO Fuel Particle.” Journal of the European Ceramic Society 38 (12): 4173-4188.
  • Parga, C. J., I. J. van Rooyen*, B. D. Coryell, W. R. Lloyd, L. N. Valenti, and H. Usman. 2017. “Room Temperature Mechanical Properties of Electron Beam Welded Zircaloy-4 Sheet.” Journal of Materials Processing Technology 241: 73-85. (*corresponding author).
  • Lillo, T. M., and I. J. van Rooyen. 2016. “Influence of Sic Grain Boundary Character on Fission Product Transport in Irradiated TRISO Fuel.” Journal of Nuclear Materials 473: 83-92.
  • van Rooyen, I. J., T. M. Lillo, and Y. Q. Wu. 2014b. “Identification of Silver and Palladium in Irradiated TRISO Coated Particles of the AGR-1 Experiment.” Journal of Nuclear Materials 446 (1-3): 178-186.
  • van Rooyen, I. J., D. E. Janney, B. D. Miller, P. A. Demkowicz, and J. Riesterer. 2014a. “Electron Microscopic Evaluation and Fission Product Identification of Irradiated TRISO Coated Particles from the Agr-1 Experiment: A Preliminary Review.” Nuclear Engineering and Design 271: 114-122. (Also presented at the HTR2012 Tokyo 28 October-1 November 2012, paper HTR2012-3-023).