Ph.D. topics

Coupling of the neutron kinetic core model DYN3D and the thermal hydraulic system code ATHLET for sodium cooled fast reactor applications

Ph.D. student:
Vincenzo Anthony Di Nora
Dr. Emil Fridman (HZDR), Dr. Konstantin Mikityuk (EPFL, PSI)
Reactor Safety


The Sodium cooled Fast Reactor (SFR) concept is one of the six reactor types of the Generation IV International Forum (GIF). The already great interest to the SFR technology starts recently growing, when France decided to build a prototype of such reactor. The safety of any reactor has to be sustained by state-of-art assessment tools. 3D neutron kinetic core models coupled with advanced thermal hydraulic system codes are being used for the safety assessment of Light Water Reactors (LWR). Efforts have been started to extent the application area of such code systems to SFRs. As far as reactor core is concerned, the HZDR nodal diffusion code DYN3D has already been updated for SFRs [1], to consider peculiar fuel thermal-expansions feedbacks, which play a negligible role in LWRs. However, a complete SFR representation would imply the modeling of thermal-hydraulic system and thermal-expansion feedbacks generated by it. In this respect, this doctoral research focuses on the DYN3D-ATHLET coupling [2] extension to SFRs application and includes the development of thermal-expansion models needed to consider those feedbacks effects arising from the expansion of metallic structures which are external to the core model but nevertheless affect it [3].


  • Extension of the DYN3D-ATHLET coupling to SFR applications.
  • Development of thermal-expansion models accounting for missing feedback effects based on the coupled code system.
  • Verification and validation of the new DYN3D-ATHLET code system.

  1. E. Nikitin and E. Fridman, “Axial fuel rod expansion model in nodal code DYN3D for SFR application,” Physor 2016, pp. 3241–3251, 2016.
  2. Y. Kozmenkov, S. Kliem, U. Rohde, “Validation and verification of the coupled neutron kinetic/thermalhydraulic system code DYN3D/ATHLET”, Annals of Nuclear Energy 84 pp. 153-165, 2015.
  3. K. Mikityuk and M. Schikorr, “New transient analysis of the Superphénix start-up tests,” in IAEA FR2013, 2013, pp. 1–10.