INITIATION OF MELT FRAGMENTATION IN FUEL-COOLANT INTERACTIONS

In many cases, the mixing of drops of hot liquid fuel with a more volatile coolant results in stable film boiling about the drops. At some later time, a disturbance can fragment the drops. This fragmentation increases the contact area between the liquids and results in a violent vaporization of the coolant. An understanding of this fragmentation mechanism is crucial to the prediction of the likelihood of violent fuel-coolant interactions. In this work, a fragmentation mechanism is proposed. It is shown how moderate pressure disturbances can cause the symmetrical collapse of a vapor film and allow the coolant to impact the drop. The impact is shown to be of sufficient strength to fragment the drop. This model quantitatively predicts the conditions necessary to lead to extensive fragmentation.