Verification of thermal stratification characteristics using a scaled-down suppression pool of the Fukushima Daiichi nuclear power plants

Abstract

This study aimed to verify the characteristics of thermal stratification induced by direct contact condensation using a 1/20-scale suppression pool of the Fukushima Daiichi nuclear power plants. A blow-down nozzle was used to inject steam into the toroidal suppression pool. Vertical temperature profiles were measured by vertically aligned thermocouples at eight positions along the circumferential direction. Flow patterns in the suppression pool were obtained using particle image velocimetry (PIV). Vertical velocity profiles were obtained every 30 min. Results showed that thermal stratification was reproduced in the scaled-down suppression pool. PIV analysis showed that two primary flows existed in the suppression pool and that the interface between the moving part and the stationary part moved according to thermal stratification development. The flow patterns obtained in this study were compared with those of our previous study using a two dimensional suppression pool.