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 Phenix end-of-life experiments. Presented in this publication are the benchmark analyses of the natural circulation test performed before the definite shutdown of the reactor. The experimental data gathered during these tests represent a unique resource to carry out validation analyses and code to code comparisons. The benchmark analyses allowed participants to investigate and verify several system and safety codes currently used in the analyses of liquid metal thermohydraulics phenomena in sodium fast reactors.