Extension of the reactor dynamics code DYN3D to SFR applications – Part II: Validation against the Phenix EOL control rod withdrawal tests

Abstract The reactor dynamics code DYN3D, initially developed for LWR applications, is being extended for steady state and transient analyses of Sodium cooled Fast Reactor (SFR) cores. The extension includes the development of the few-group cross section generation methodology, updating of the thermal-hydraulic database with thermal-physical properties of sodium, and development of the thermal-mechanical model to account for thermal expansion effects of the core components. Part I of the paper provided a detailed description of the recently implemented thermal expansion models able to treat axial expansion of fuel rod and radial expansion of diagrid. The results of the initial verification tests were also presented in Part I of the paper. The capability of the extended version of DYN3D to perform steady state and transient analyses of SFR cores was validated using selected tests from the end-of-life experiments conducted at the Phenix reactor. Part II of the paper reports on the results of the steady state analysis of the control rod withdrawal tests from the Phenix end-of-life experiments. The transient analysis of the initial stage of the natural circulation test is covered in Part III of the paper.