CIGMA experimental investigation on heat and mass transfer phenomena induced by natural convection with density stratification in the enclosure vessel

Abe, Satoshi  ; Hamdani, A.  ; Ishigaki, Masahiro ; Shibamoto, Yasuteru 

The composite behavior of heat and mass transfer is one of the significant issues in discussing a nuclear containment thermal-hydraulic during a severe accident. Previous studies focused on the mixing behavior by the natural convection. In addition to this, since outer surface cooling is considered to be one of the AM measures to prevent the over-temperature damage, an investigation of the relationship between stratification behavior and the ability of outer cooling is required. This paper describes an experimental investigation on natural convection induced by outer cooling in the presence of the density stratification consists of air-helium (as mimic gas of hydrogen) gas mixture. By using the unique outer cooling system of the CIGMA facility of which test vessel is cylindrical with 2.5 m diameter and 11 m height), it is clarified that the relative cooling location to the stratification plays an important role to decide the composite behavior of heat and mass transfer in the enclosed vessel. This knowledge is useful for understanding the interaction behavior of heat and mass transport during the outer cooling as one of the AM measures.