For both the front and slug mixing cases, the nominal pump transients are kept the same with steady state flow rate of approximately 8 liters/sec. The start-up transient for the pump consists of a gradual ramp over a span of approximately 12.5 seconds, which was selected to match the corresponding tests performed in the integral facility.

Repeatable inlet concentration boundary conditions are generated using a small drain valve at the bottom of the lowered loop upstream of the pump. For both the front and the slug, the leading interface is very sharp and repeatable, while the trailing interface on the slug has a slightly greater variability due to the way the slug is generated.

Front Injection
Animated sequence of front concentration images for nominal injection transient

Slug Injection
Animated sequence of slug concentration images for nominal injection transient

Flow Pattern Variations
Observations of variations in the flow pattern with nominal injection conditions

Velocity Field
LDV velocity maps of selected radial downcomer planes