R&D of the next generation safety analysis methods for fast reactors with new computational science and technology, 4; Experimental analyses by SIMMER-III for the integral verification of COMPASS

Yamano, Hidemasa   ; Tobita, Yoshiharu

This paper describes experimental analyses using SIMMER-III, which were precedently carried out for the integral verification of the COMPASS code. Two topics of key phenomena in CDAs were here presented: molten fuel freezing and dispersion; and boiling behavior of molten fuel pool. To analyze the fuel freezing behavior, the GEYSER out-of-pile and the CABRI-EFM1 in-pile experiments were selected. The SIMMER-III calculation well agreed with fuel penetration length measured in GEYSER. The freezing behavior in CABRI-EFM1 was also reasonably simulated by SIMMER-III. The boiling pool consisting of molten fuel/steel mixtures is characterized by the heat transfer between fuel and steel. The CABRI-TPA2 experiment has suggested less transient heat flux from fuel to steel due to a steel vapor blanketing around a steel droplet. SIMMER-III well simulated the steel boiling behavior observed in the CABRI-TPA2 experiment by reducing the heat transfer coefficients between fuel and steel.