Assessment of multi-dimensional analysis cacpacity of the MARS using the OECD-SETH PANDA tests

The objectives of OECD/NEA-PANDA tests are to validate and assess computer codes that analyze the non-condensable gas concentrations and mixing phenomena in a reactor containment building. Especially, the main issue is multi-dimensional analysis capability which is involved in the mixing of non-condensable gases, i. e. hydrogen. The main tests consist of a superheated steam flow injection into a large vessel initially filled with air or air/helium mixtures. Then the temperature and concentration of noncondensable gases are measured. A pre-calculation has been performed with the MARS about PANDA Tests even though MARS is not a containment analysis code. Three cases among 25 PANDA Tests are selected and are modeled to simulate the jet plumes and air mixing in a large vessel. The dimensions of large vessel are 4 m diameter and 8 m height. For the conclusion of calculation, the cylindrical vessel which dimensions are 4 m diameter and 8 m height was simplified as rectangular geometry. It is revealed that the MARS code has the capability to distinguish the multi-dimensional distribution of the velocity and the temperature fields