A study on the performance of a nuclear reactor building floor baffle for particulate debris sedimentation

Highlights: ► Reactor building floor baffle is proposed as a structure to enhance particle sedimentation. ► The performance of the baffle is experimentally studied. ► Simulant particle transport properties and settling efficiency are measured. ► Tests show that settling efficiencies greater than 80% can be potentially achieved in the plant. ► 3D computations show the particle settling is due to downward and backward flow. - Abstract: Nuclear reactor building floor baffle which is a simple structure reducing flow velocity and thus promote particulate debris sedimentation before reaching the emergency sump is proposed and the performance is experimentally studied. In order to account for the particle movement at the baffle upstream, tumbling and lifting velocities of the simulant debris particles are measured in a sedimentation test flume which is designed for simulating reactor building floor waterway. Settling efficiencies are measured using a test flume for various conditions such as water velocity, particle size, and the type and mesh size of the baffle. The tests show that settling efficiencies greater than 80% can be potentially achieved when the baffle is applied to a real plant. Three-dimensional fluid dynamic computations are employed as a supplementary purpose of explaining the mechanism of particle settling by downward flow and resulting forces which are formed and enhance the particle settlement before the baffle on the floor.