Multi-dimensional pool analysis of Phenix end-of-life natural circulation test with MARS-LMR code

Highlights: • The natural circulation test performed in Phenix reactor has been analyzed with MARS-LMR code. • A multi-dimensional approach for the hot pool and the cold pool has been adopted in the analysis. • A detailed comparison between the test data and the simulation results has been performed. - Abstract: The MARS-LMR code is a key system analysis tool for the development of a sodium-cooled fast reactor in Korea. The code has been successfully applied for the transient analysis of conceptual designs of SFR since 2007 mainly based on a one-dimensional approach. In recent studies, it was identified that one-dimensional modeling of a pool-type SFR has limitations on describing complicated thermal–hydraulic phenomena in pool regions at natural circulation conditions. In the present study, the natural circulation test performed in Phenix reactor by CEA has been analyzed with a multi-dimensional approach of MARS-LMR. Only the hot pool and the cold pool regions are modeled multi-dimensionally and other parts of the plant are described one-dimensionally in the analysis. Even though a very careful treatment of initial flow condition is required, this multi-dimensional modeling of pool regions results in quite accurate prediction of the temperature distributions measured at several points during the test when it is compared to the results with one-dimensional pool nodalization. It is suggested that a detailed modeling of pool regions is essential for the future analysis of pool-type SFRs. The multi-dimensional modeling capability can be enhanced through the improvement of the existing system code or by the combination of system code and CFD code