Parametric sensitivity study on the reflooding models of the MARS code based on 6x6 Rod Bundle Test Results

A 6x6 reflood test facility, ATHER facility for Advanced Thermal Hydraulic Evaluation of Reflood phenomena) has been constructed and operated by KAERJ (Korea Atomic Energy Research Institute) in order to investigate the reflooding phenomena in a rod bundle. A series of bottom reflood tests were carried out for various conditions. Subsequently, counterpart reflood tests on the RBHT (Rod Bundle Heat Transfer,) data in PSU (Penn. State University) were also conducted in order to investigate the effects of the heat flux on the peak cladding temperature and the quenching behavior The MARS3. 1 code was assessed with the obtained data in order to investigate the parametric effects on the prediction accuracy. The one dimensional PIPE module of the MARS code was used. In general, the prediction accuracy of the PCT was reasonable, but the MARS code predicts a later quenching behavior than the data, especially for high heat flux conditions. In particular the prediction becomes poor downstream, far from the inlet of the test section. (authors)