Independent Assessment of MARS 3D Features: Use of Experimental Data and CFD Support

Recent developments of special models and correlations extended the system TH codes capabilities to simulate 3D phenomena. A code assessment process is always needed whenever the new code features are intended for nuclear reactor design and/or licensing applications. The Korean Thermal-Hydraulic code MARS (developed by Korea Atomic Energy Research Institute) experiences such an improvement, extending the 1D flow field formulation. In this respect the present paper describes the activity conducted to assess the 3D features of the MARS code by independent users. The adopted experimental data are gathered in a test conducted at the ROCOM (Rossendorf Coolant Mixing Model) experimental facility, which reproduced a pump start-up scenario. In addition, to support the interpretation of experimental data and system code results, a CFD analysis has been also performed. The assessment activity includes a comparison with RELAP5-3D© code, a set of sensitivity calculations and the use of the FFTBM package