LWR steam spike phenomenology: debris bed quenching experiments

An experimental investigation is reported whose objective is to provide an understanding of the thermal interaction between superheated core debris and water during postulated light-water reactor degraded core accidents. The experiment was designed to study the heat transfer characteristics of superheated spheres as they are quenched in a packed bed configuration by an overlying pool of water. The results of the experiment are applied to understanding of the containment steam spike phenomenon. Three-millimeter stainless steel spheres were heated in an oven to temperatures between 533 and 9770K, and subsequently transferred to a vertical 108.2 mm i.d. stainless steel vessel. Water at temperatures between 2740K and 3600K was released on to the spheres and the resulting thermal interaction was observed. Packed beds were studied whose nominal heights were in the range 200 mm to 400 mm. The experiments were carried out at constant pressure, with the steam vented to the atmosphere. Bed and wall temperature traces are presented for a range of experimental conditions