• Ph.D., University of California, Los Angeles, 1981
  • M.S., Louisiana State University, 1977
  • B.S., Illinois Institute of Technology, 1975

Research Areas


Came to Tech in Fall 1992 as an Associate Professor. Prior was a Principal Engineer at General Electric Nuclear Energy.


Since joining Georgia Tech, Dr. Rahnema has been active in the areas of variational and perturbation theory, nodal methods, criticality safety analysis, and benchmark methods. He has been developing boundary condition and boundary perturbation methods for the neutron transport (Boltzmann) equation and its diffusion approximation. The methods deal with calculating the perturbed eigenvalue or a function of the solution for systems with a slightly perturbed boundary and boundary condition. Boundary perturbation formalisms can be used in the analysis of passively safe nuclear reactors. Variational principles for eigenvalues as well as for ratios of linear neutron flux functionals have been developed to treat boundary conditions and boundary perturbations in systems described by the steady-state inhomogeneous and homogeneous Boltzmann equations. The principles are also useful in developing numerical models such as a heterogeneous finite-element model for reactor core calculations. Nuclear criticality safety is directly dependent on the accuracy of the numerical tools used by nuclear criticality safety specialists to analyze operations with fissionable materials. Dr. Rahnema has been conducting collaborative research work with the Westinghouse Savannah River Company and Westinghouse Safety Management Solutions to develop defensible benchmark descriptions of critical experiments.

Dr. Rahnema is also involved in the design and measurement of subcritical experiments with fresh fuel. The project includes the development of a nodal diffusion theory computational tool for the criticality analysis of Westinghouse Savannah River Companys spent fuel storage configurations. The originality of this method is that it achieves Monte Carlo accuracy using a fast and simple diffusion theory model.


  • National Science Foundation, Faculty Early Career Development Award, 2011-2016
  • American Nuclear Society
    • Mathematics and Computation Division Chair, 2010-2011 and 1999-2000
    • Reactor Physic Division Chair, 2007-2008
    • Fellow, 2003
  • Southeastern Universities Nuclear Research Institute for Science and Education (SUNRISE) Chair, 2006-2010
  • Journal on Transport Theory and Statistical Physics  Conference Special Issue Guest Editor, 2001
  • 16th International Conference on Transport Theory Organizing Committee Chair, 1999


  • Boundary Condition Adjustment Methods and Systems, U. S. Patent 7,676,015B2, with Ben Forget, March 9, 2010.

Representative Publications

  • Justin M. Pounders and Farzad Rahnema. 2010. Moment-Conserving Histopolating B-Splines for Continuous Tally Estimation. PHYSOR 2010 – Advances in Reactor Physics to Power the Nuclear Renaissance, Pittsburgh, Pennsylvania, May 9-14, 2010. On CD-ROM, American Nuclear Society, LaGrange Park, IL.
  • Justin Pounders and Farzad Rahnema. 2009. On Diffusion Coefficients for Reactor Applications. Nuclear Science and Engineering 163 3), 243-262.
  • Nathanael Hudson, A. Ougouag, Farzad Rahnema and Hans Gougar. 2009. A Pebble Bed Reactor Cross Section Methodology. Annals of Nuclear Energy 36 (8), 1138-1150.
  • Dingkang Zhang and Farzad Rahnema. 2009. A Hybrid Diffusion/Transport Method. International Conference on Mathematic, Computational Methods & Reactor Physics (M&C 2009), Saratoga Spring, New York, May 3-7, 2009. On CD-ROM, American Nuclear Society, LaGrange Park, IL.
  • Steven Douglass, Farzad Rahnema and Benoit Forget. 2008. A Generalized Energy Condensation Theory. Nuclear Science and Engineering 160(1), 41-58.