Independent analysis for the Assessment of Multidimensional Features of the MARS Code

A request was formulated to University of Pisa by the Government regulatory body in Korea KINS (Korean Institute for Nuclear Safety) to assess the three dimensional capabilities of the MARS code developed in Korea. An innovative approach was proposed by University of Pisa including the use of both system thermal-hydraulic code (having, as far as possible, qualified 3D capabilities) and a commercial qualified Computational Fluid-Dynamic (CFD) code. An experiment in one German facility where the three dimensional nature of flow was measured was simulated by the three codes (i.e. the MARS, the RELAP5/3D and the CFX). The adopted approach involved the characterization of a quantitative measure of accuracy including spatial distribution of parameters at the basis of a figure of Merit and the use of the Fast Fourier Transform based method (FFTBM) for the time variation of the selected parameters. The activity, based on the comparison with experimental data, demonstrated the capabilities of the MARS code (i.e. same level-of-error as other state-of-art-recognized computational tools)