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Aysenur Toptan

Computational Scientist

Research Areas:


Aysenur Toptan works as a computational scientist in the Bison team of INL since April 2020. She started working in the Bison team as the fuel modeling and simulation postdoctoral researcher in August 2019. She has been awarded as the outstanding postdoc of the year 2020. She received her Ph.D. in nuclear engineering from North Carolina State University. Her doctoral study was sponsored by Consortium for Advanced Simulation of LWRs (CASL) through the Oak Ridge National Laboratory. Toptan has worked on modeling and simulation of various nuclear engineering problems, including nuclear fuel performance and thermal hydraulics analyses. She has focused mostly on the development, verification, validation, calibration, and uncertainty quantification of computational physics tools. Her research at INL focuses on the next-generation computational nuclear fuel performance software, Bison that is based on the open-source MOOSE framework. She holds M.Sc. degree in nuclear engineering from the Penn State University and B.Sc. degree in nuclear energy engineering from Hacettepe University as the top-ranked student in the department.

Digital Profiles:

​Orcid ID: 0000-0003-4250-6336


Ph.D., Nuclear Engineering – North Carolina State University (North Carolina, USA)
M.Sc., Nuclear Engineering – The Pennsylvania State University (State College, USA)
B.Sc., Nuclear Energy Engineering – Hacettepe University (Ankara, Turkey)


W. Jiang, J. D. Hales, B. W. Spencer, B. Collin, A. E. Slaughter, S. R. Novascone, A. Toptan, K. A. Gamble, and R. Gardner, “TRISO particle fuel performance modeling and failure analysis with BISON," Journal of Nuclear Materials, p. 152795, 2021. Available at  

A. Toptan, N. W. Porter, J. D. Hales, B. W. Spencer, M. Pilch, and R. L. Williamson, “Construction of a code verification matrix for heat conduction with finite element code applications," Journal of Verification, Validation and Uncertainty Quantification, Transactions of the ASME, vol. 5(4), p. 041002 (15 pages), December 2020. Available at  

A. Toptan, J. D. Hales, R. L. Williamson, S. R. Novascone, G. Pastore, and D. J. Kropaczek, “Modeling of gap conductance for LWR fuel rods applied in the BISON code," Journal of Nuclear Science and Technology, vol. 57(8), pp. 963–974, 2020. Available at  

A. Toptan, D. J. Kropaczek, and M. N. Avramova, “Gap conductance modeling II: Optimized model for UO2-Zircaloy interfaces," Nuclear Engineering and Design, vol. 355, p. 110289 (7 pages), December 2019. Available at  

A. Toptan, D. J. Kropaczek, and M. N. Avramova, “Gap conductance modeling I: Theoretical considerations on the model for single- and multi- component gases," Nuclear Engineering and Design, vol. 353, p. 110283 (7 pages), November 2019. Available at  

A. Toptan, D. J. Kropaczek, and M. N. Avramova, “On the validity of dilute gas assumption for gap conductance calculations in nuclear fuel performance codes," Nuclear Engineering and Design, vol. 350, pp. 1–8, August 2019. Available at

A. Toptan, R. K. Salko, M. N. Avramova, K. Clarno, and D. J. Kropaczek, “A new fuel modeling capability, CTFFuel, with a case study on the fuel thermal conductivity degradation," Nuclear Engineering and Design, vol. 341, pp. 248–258, January 2018. Available at

A. Toptan, N. W. Porter, R. K. Salko, and M. N. Avramova, “Implementation and assessment of wall friction models for LWR core analysis," Annals of Nuclear Energy, vol. 115, pp. 565–572, May 2018. Available at

T. Worosz, M. Bernard, R. Kong, A. Toptan, S. Kim, and C. Hoxie, “Sensitivity studies on the multi-sensor conductivity probe measurement technique for two-phase flows," Nuclear Engineering and Design, vol. 310, pp. 552–563, December 2016. Available at


INL Expanded Recognition Award 2020

INL Outstanding Postdoc Award 2020

The Robert M. Graham Award, 2015, College of Engineering, Penn State University

Ihsan Dogramaci Supreme Success Award, 2011, Hacettepe University

Top-Ranking Student of the Nuclear Engineering Department, 2011, Hacettepe University

Research Interests:

​Computational nuclear fuel performance, gap conductance, heat transfer, VVUQ

Version: 4.0
Created at 2/8/2021 3:56 PM by Tiffany M. Adams
Last modified at 11/22/2021 3:11 PM by Jason D. Hales