The study of natural convection with decay heat source in an open horizontal neutron production target

The research examines the phenomenon of natural convection heat transfer induced by decay heat sources within the intricate flow channels of the target. A three-dimensional model of the target was developed utilizing principles of fluid dynamics and numerical methods for heat transfer. The research emphasizes the micro-convective and non-flow heat transfer phenomena occurring within the confined spaces of the target’s intricate flow channels. Simulations of boundary conditions pertinent to a power failure incident were conducted and subsequently validated against experimental data. The findings indicated that the temperatures at the pressure inlet and pressure outlet boundary conditions closely aligned with the experimental measurements, recorded at 52.7 ℃ and 51.5 ℃, respectively, with an error margin of less than 3%. Additionally, the investigation revealed that the external surrounding heat transfer coefficient has a negligible effect on the internal temperature distribution. This research offers significant insights and recommendations for assessing accident scenarios at the target station for the China Spallation Neutron Source (CSNS) Ⅱ upgrade project.