Dan Ilas

Dan Ilas


Dan Ilas is a nuclear engineer and a member of the R&D staff in the Radiation Transport Group of the Reactor and Nuclear Systems Division at Oak Ridge National Laboratory.

Dan Ilas graduated in 1986 from the Faculty of Physics of the University of Bucharest, Romania with a 5-year degree in Engineering Physics. After working for nine years on solving various problems related to nuclear reactors in two research institutions in Romania (CANDU startup simulations, exploration of boron carbide shielding for fast reactors, and decommissioning of a research reactor), Dan started a Ph.D. program in nuclear engineering at Georgia Tech in September 1995. Upon graduation in spring of 2001, Dan worked for two and a half years as a postdoc at Louisiana State University in Baton Rouge, LA, exploring the benefits of radiation in medical physics - radiation therapy. He returned at Tech as a postdoc for another year, being enrolled in the first class of the Sam Nunn Security Program, to study the benefits and the proliferation resistance of the new types of nuclear reactors.

Since November 2004, Dan works at Oak Ridge National Laboratory. His activity at the Lab encompassed a diversity of domains such as reactor physics, medical physics, health physics, radiation protection and shielding and nuclear waste disposal. Over the past few years, an important component of Dan's work focused on the analysis of the characteristics of the new types of nuclear reactors. He led the neutronics efforts for the design of the molten salt-cooled SmAHTR, AHTR, and SmAHTR-CTC ORNL’s reactor concepts. Presently he serves as a neutronics consultant for the 5-million DOE-funded Georgia Tech-led university project “Integrated Approach to Fluoride High Temperature Reactor (FHR) Technology and Licensing Challenges”.



Source term and dose rates associated with radioisotope shipping.

Consulting for university-led (Georgia Tech) NEUP IRP project on AHTR.




  1. D. Ilas, D. E. Holcomb, J. C. Gehin, SmAHTR-CTC Neutronic Design, Proceedings of PHYSOR 2014 – The Role of Reactor Physics Toward a Sustainable Future, The Westin Miyako, Kyoto, Japan, September 28 – October 3, 2014, on CD-ROM (2014).

  2. D. E. Holcomb, D. Ilas, B. Middleton, M. Arieta,Small, Modular Advanced High Temperature Reactor–Carbonate Thermochemical Cycle, ORNL Report ORNL/TM-2014/88, ORNL, Oak Ridge, TN, USA, March 2014.

  3. A. T. Cisneros, D. Ilas, Neutronics and Depletion Methods for Multibatch Fluoride Salt-Cooled High-Temperature Reactors with Slab Fuel Geometry, Nuclear Technology, Vol. 183, Issue 3, page 331-340, September 2013

  4. R. P. Kelly, D. Ilas, Verification of a Depletion Method in SCALE for the Advanced High-Temperature Reactor Nuclear Technology, Vol. 183, Issue 3, page 391-397, September 2013

  5. V. K. Varma, D. E. Holcomb, F. J. Peretz, E. C. Bradley, D. Ilas, A. L. Qualls, N. M. Zaharia, AHTR Mechanical, Structural, and Neutronic Preconceptual Design, ORNL Report ORNL/TM-2012/320, ORNL, Oak Ridge, TN, USA, Sept. 2012.

  6. D. E. Holcomb, D. Ilas, A. L. Qualls, F. J. Peretz, V. K. Varma, E. C. Bradley, A. T. Cisneros, Current Status of the Advanced High Temperature Reactor, Proceedings of ICAPP ’12 Chicago, IL, USA, June 24-28, 2012.

  7. D. Ilas, D. E. Holcomb, V. K. Varma, Advanced High-Temperature Reactor Neutronic Core Design, Proceedings of PHYSOR 2012 – Advances in Reactor Physics – Linking Research, Industry, and Education, Knoxville, TN, USA, April 15-20, 2012.

  8. D. E. Holcomb, D. Ilas, V. K. Varma, A. T. Cisneros, R. P. Kelly, J. C. Gehin, Core and Refueling Design Studies for the Advanced High Temperature Reactor, ORNL Report ORNL/TM-2011/365, ORNL, Oak Ridge, TN, USA, September 2011.

  9. S. R. Greene, J. C. Gehin, D. E. Holcomb, J. J. Carbajo, D. Ilas, A. T. Cisneros, V. K. Varma, W. R. Corwin, D. F. Wilson, G. L. Yoder Jr., A. L. Qualls, F. J. Peretz, G. F. Flanagan, D. A. Clayton, E. C. Bradley, G. L. Bell, J. D. Hunn, P. J. Pappano, M. S. Cetiner, Pre-Conceptual Design of a Fluoride-Salt-Cooled Small Modular Advanced High-Temperature Reactor (SmAHTR), ORNL Report ORNL/TM-2010/199, ORNL, Oak Ridge, TN, USA, December 2010.

  10. D. Ilas, SCALE Code Validation for Prismatic High-Temperature Gas-Cooled Reactors, Nuclear Technology, Vol. 183, Issue 3, page 379-390, September 2013