This publication is based on the experience of an IAEA coordinated research project on control rod withdrawal and sodium natural circulation tests performed during the Phénix end-of-life experiments. The publication presents benchmark analyses on the control rod withdrawal tests. The experimental data gathered during these tests represent a unique resource for validation analyses and code-to-code comparisons. The benchmark analyses allowed participants to investigate and verify neutronics codes used in the analysis of sodium cooled fast reactor cores, as far as their capability to correctly evaluate relevant safety aspects such as control rod efficiency and core power deformation due to the insertion and withdrawal of control rods.
