Code-to-code SIMMER/FRENETIC comparison for the multiphysics simulation of the ALFRED core

This paper presents a neutronic benchmark between FRENETIC, a code developed for the computationally efficient full-core analysis of the accidental transients in liquid-metal fast reactors, and SIMMER, which is a reference tool for the analysis of such kind of systems in accidental conditions. The performances of the two codes are compared in an increasingly detailed simulation framework, in order to better highlight the impact of the different methods available on the output results of practical interest, such as the linear power for each sub-assembly. To ensure a fair comparison between the two codes, they are provided with the same set of input multi-group material constants, computed with the Monte Carlo code Serpent 2. The main neutronic quantities computed by FRENETIC are compared with those produced by SIMMER, using at first a cylindrical 2D core description and, then, a detailed 3D model. The assessment shows that, despite their differences, the neutronic modules of the two codes are in satisfactory good agreement, thus providing a solid ground for future thermal-hydraulics and, eventually, for multi-physics benchmarking activities.