Before the final shutdown of the prototype power fast reactor PHENIX, the CEA, EDF and AREVA decided to perform a final set of experiments, in order to gather important data and knowledge about several aspects of the operation of pool-type sodium-cooled fast reactors.
Recognizing this unique opportunity offered by the PHENIX tests programme and thanks to CEA readiness to open it for international collaboration, in 2007 the IAEA, within the framework of the Technical Working Group on Fast Reactors (TWG-FR) activities, decided to launch a Coordinated Research Project (CRP), devoted to benchmarking analyses on "Control Rod Withdrawal and Sodium Natural Circulation Tests Performed During the PHENIX End-of-Life Experiments". The overall objective of the CRP was to improve the participants' analytical capabilities in various fields of research and design of sodium-cooled fast reactors. Actually, a necessary condition towards achieving this objective is a wide international verification and validation effort of the methods and codes currently employed in the fields of fast reactor neutronics, thermal hydraulics and plant dynamics.
In particular, the benchmark analysis of the control rod withdrawal test aimed at improving the understanding of the fast reactor neutronics, as well as the verification and validation of the related simulation methods and codes.
The CRP was performed by experts coming from CEA (France), ANL (USA), IGCAR (India), IPPE (Russia), IRSN (France), JAEA (Japan), KIT (Germany) and PSI (Switzerland).
After a short description of the test conducted in the Phenix reactor, this paper presents some results obtained in the course of the CRP with special emphasis on control rod efficiencies and power deformation by subassemblies. The paper also discusses the discrepancies found when comparing calculated results with experimental data as well as some preliminary conclusions on the source of these discrepancies.