The studies of mixing and thermal stratification in SMR containments

Thermal mixing and stratification, which are common phenomena in the passive containment cooling system, may occur in the containments of the small modular reactors as well during the loss of coolant accidents or the main steam line break accidents. This paper studies the mixing and thermal stratification caused by the plumes or buoyant jets in the small containments. The experiments in a steel containment were conducted with various jet inlet temperatures and flow rates to identify their influence on the thermal stratification phenomena. The temperature distributions with height as well as the contour maps over cross section in the containment are given to illustrate the thermal stratification. The flow visualization was illustrated in a glass simulated containment to obtain detailed understandings of the jet mixing and fluid stratification development. The experiment results agree well with the computation results.