Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

In recent years, the reactor core simulator DYN3D has become a frequently used tool for neutronic analyses of Sodium cooled Fast Reactors (SFRs) by the Reactor Safety Group of the Helmholtz-Zentrum Dresden-Rossendorf. The capabilities of the code are constantly expanding with new models, such as the various thermal expansion models relevant for SFR neutronic behavior. This study presents the extension of the radial expansion module for the modeling of non-uniform core expansions, i.e. core flowerings. Since DYN3D uses regular numerical meshes for its neutronic solvers, the implementation of the coordinate transformation method (CTM) was performed to cope with non-uniform core deformations. First, the implementation of the CTM was tested on a realistic SFR core for lifelike core flowering scenarios. The DYN3D results were compared against the Monte Carlo reference solutions. Second, DYN3D was validated against the core flowering experiment performed in the Phenix reactor. The measured reactivity effects of the static deformations were used to assess the DYN3D performance. At both stages, the obtained results show an acceptable agreement with the references, thus demonstrating the applicabilty of DYN3D for modeling various core flowering scenarios.