DCH DISPERSAL AND ENTRAINMENT EXPERIMENT IN A SCALED ANNULAR CAVITY

The objective of this experiment was to measure the amount of cerium d ispersal and the droplet size distribution during high pressure melt e jection from a CE reactor. The melt and the steam flowed to the contai nment through a narrow annular cavity. The experiment was carried out on a 1/20th scaled model of the cavity and the containment. The scalin g was based on dimensionless numbers obtained from a two-phase flow mo del of the dispersal and entrainment mechanisms in the cavity. Further more, the model shows that the flow in the cavity was choked, so high levels of dispersal and entrainment were possible. The experiment cons isted of air-water, air-helium, air-woods metal and helium-woods metal tests; the main result being that the level of dispersal was very hig h in all cases. The woods metal data supported a separated flow model in the cavity, implying that the gas choked velocity was very high and the droplets very small. In contrast, the measured drop sizes for the water tests were much larger than the separated flow model prediction s. This discrepancy could not be resolved because the entrainment mech anism is not properly understood at the present time.