Abstract

Large quantities of hydrogen are generated and released into the containment due to zirconium-water reaction under severe accident conditions. Hydrogen tends to accumulate on the top of containment and form a stratified layer. The stratification of hydrogen may be eroded by several measures, such as gas jet, spray and ventilation. A series of tests including helium/air stratification, helium/air/steam stratification, as well as gas stratification eroded by steam jet have been performed on COTHYD facility, high-quality data obtained from the tests set up a good basis for physical phenomena research and code validation. The COTHYD (COntainment Thermal-hydraulics and HYdrogen Distribution) is a large-scale containment test facility designed and constructed for studying the containment thermal hydraulics behavior and gas distribution in PWR during severe accidents by CGN (China General Nuclear Power Group). In this work, helium was discharged from top and different injection rates were selected to study the formation of helium stratification and set up a suitable stratification for erosion condition. Steam with different interaction Froude number were injected upward from bottom to break up the helium stratification. Results of different erosion processes demonstrated that the interaction Froude number of steam jet can be used to distinguish the ability of steam jet to erode the stratified layer.

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