Simulation of the Natural Convection Test of Phenix Reactor Using Modified ATHLET

The sodium-cooled fast reactor (SFR) is gathering worldwide attention for its features of the fast-spectrum reactor and closed fuel recycle system. This paper presents the modification of the ATHLET code for application to SFRs. The thermal-hydraulic computer code ATHLET is developed by Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) in Germany for light water reactors analysis. In this paper, a sodium properties package is implemented in to the ATHLET code, and heat transfer correlations for sodium are also added for heat transfer prediction. To evaluate the capability of the modified code, the Phenix reactor, a SFR operated by French Alternative Energies and Atomic Energy Commission (CEA) from 1973 to 2009, is modeled. The scenario of transient from forced to natural convection is simulated and analyzed. The results are compared with the experimental data of the natural convection ultimate test of the Phenix facility. Results achieved so far indicate good applicability of the modified ATHLET code.