Modeling of the FFTF isothermal physics tests with the Serpent and DYN3D codes

Highlights: • The FFTF isothermal physics tests were used for neutronic code validation. • 3D full core solutions were obtained with Serpent and DYN3D codes. • Few-group cross sections were generated with Serpent and corrected with SPH method. • Serpent Monte Carlo code and DYN3D nodal code agreed well with the experiment. - Abstract: In this study, the isothermal physics tests performed on the fully loaded core of the Fast Flux Test Facility are analyzed with the Monte Carlo code Serpent and with the deterministic core simulator DYN3D. The selected tests comprise two neutron spectra measurements and a multitude of reactivity measurements (32 cases with control rod movements and one case for isothermal temperature coefficient). While the flux spectra are calculated only with Serpent, the reactivity effects are evaluated with the both codes. The homogenized few-group cross sections for DYN3D calculations are generated with Serpent. The obtained numerical results are in a very good agreement as compared to the experimental data. Additionally, a comparison of radial power distributions is presented between DYN3D and Serpent calculations, demonstrating an adequate performance of the nodal code DYN3D. This paper provides an additional contribution to the validation of both codes for neutronic analyses of Sodium cooled Fast Reactor cores.