(193e) Bubble Dynamics in Pressurized Water Small Modular Reactor Core Under Loss of Coolant Accident Conditions

The present investigation aimed to design and construct a downscaled test facility that simulates the bubble dynamics and void fraction in Pressurized Water Small Modular Reactor (PWSMR) to obtain detailed data on the core bubble dynamics and void fractions under loss of coolant scenarios using advanced measurement techniques, to advance the knowledge of fluid dynamics of the pressurized water reactors. The presently available test data lacks the requisite resolution for validating computational fluid dynamics (CFD) and benchmarking tests. To address this research gap, a test section was fabricated with a transparent square wall of 5x5 rods and distinctive grid spacers, utilizing cutting-edge 3D printing techniques. The test facility employed water and air as working fluids, and an innovative 4-point optical fiber probe and data acquisition system were developed to measure bubble characteristics such as local gas holdup, bubble chord length, specific interfacial area, bubble velocity, bubble passage frequency, and their distribution and time series. The experiments were performed at various liquid various gas and liquid flow rates covering bubbly and churn turbulent flow regimes. The acquired data provides valuable information for validating CFD and assessing the distribution of bubbles.